Steering control device

Abstract

The present application relates to a steering control device. A steering control device (50) controls a turning motor that generates a turning force for turning a turning wheel whose power transmission to and from a steering wheel is cut off. The steering control device (50) includes a first processor configured to change a steering angle ratio, which is a ratio of a turning angle of the turning wheel to a steering angle of the steering wheel, in accordance with a vehicle speed by controlling the turning motor, and a second processor configured to change a degree of change of the change of the steering angle ratio with respect to the vehicle speed in accordance with a steering state or a vehicle state.

Description

Technical Field

[0001] This invention relates to a steering control device. Background Technology

[0002] A so-called steer-by-wire system is known in which the power transmission path between the steering wheel and the wheels is interrupted. This steering system includes: a reaction motor, which is the source of the steering reaction force applied to the steering shaft; and a rotation motor, which is the source of the rotational force used to rotate the wheels. When the vehicle is in motion, the control unit for the steering system uses the reaction motor to generate the steering reaction force and uses the rotation motor to rotate the wheels. There is a need to improve the steering characteristics of such a steering system.

[0003] For example, the control device described in Japanese Unexamined Patent Application Publication No. 2013-209026 (JP 2013-209026 A) changes the steering angle ratio according to vehicle speed for the purpose of improving steering characteristics. The steering angle ratio is the ratio of the rotation angle of the wheels to the steering angle of the steering wheel. The steering angle ratio is set to a value that increases as vehicle speed increases. As the steering angle ratio decreases, the rotation angle of the wheels changes more rapidly when the steering wheel is operated. As the steering angle ratio increases, the rotation angle of the wheels changes more slowly when the steering wheel is operated.

[0004] Therefore, when the vehicle enters a parking garage or similar area at low speeds, it receives a larger amount of steering wheel rotation, thus ensuring vehicle maneuverability. When the vehicle changes lanes or similar situations at high speeds, the amount of steering wheel rotation decreases, thus ensuring vehicle driving stability. Summary of the Invention

[0005] In general control devices in the prior art, including the control device described in JP 2013-209026 A, which have the function of changing the steering angle ratio according to vehicle speed, there is a concern that, for example, when the vehicle decelerates or accelerates while turning, the steering angle ratio changes with the vehicle speed, and therefore the turning angle of the wheels also changes. Therefore, there is a concern that vehicle behavior may occur that is not intended by the driver.

[0006] For example, when a vehicle decelerates while turning, the rotation angle changes significantly as the vehicle speed decreases. Therefore, the vehicle's trajectory may change, causing it to move inward relative to the driver's intended trajectory. Conversely, when a vehicle accelerates while turning, the rotation angle changes less significantly as the vehicle speed increases. Therefore, the vehicle's trajectory may change, causing it to jut outward from the driver's intended trajectory.

[0007] In particular, when a vehicle's speed changes while the steering wheel is turned at a constant steering angle, the rotation angle of the steering wheels will change with the vehicle's speed, even if the steering wheel remains at a constant angle. Therefore, the driver may experience discomfort due to the inability to maintain the intended driving trajectory.

[0008] The present invention provides a steering control device that can suppress changes in vehicle behavior not intended by the driver.

[0009] One aspect of the present invention provides a steering control device. The steering control device controls a rotary motor that generates a rotational force to rotate wheels whose power transmission to and from the steering wheel is interrupted. The steering control device includes: a first processor configured to change a steering angle ratio based on vehicle speed by controlling the rotary motor, the steering angle ratio being the ratio of the rotation angle of the wheels to the steering angle of the steering wheel; and a second processor configured to change the degree of variation of the steering angle ratio relative to the vehicle speed based on steering state or vehicle state.

[0010] According to this configuration, an appropriate steering angle ratio is obtained based on the steering state or vehicle state. Therefore, changes in vehicle behavior not intended by the driver can be suppressed. In the steering control unit, the second processor can be configured to prevent the steering angle ratio from changing with respect to vehicle speed when the steering wheel is held at a constant steering angle relative to the neutral position or when the vehicle is turning.

[0011] According to this configuration, when the steering wheel is held at a constant steering angle or when the vehicle is turning, the steering angle ratio does not change with the vehicle speed, and therefore the rotation angle of the turning wheels does not change with the vehicle speed. Therefore, when the steering wheel is held at a constant steering angle or when the vehicle is turning, unintended vehicle behavior when the vehicle speed changes can be suppressed.

[0012] In the steering control unit, the second processor can be configured to slow down the change in the steering angle ratio relative to the vehicle speed when the steering wheel is held at a constant steering angle relative to the neutral position or when the vehicle is turning.

[0013] According to this configuration, when the steering wheel is held at a constant steering angle or when the vehicle is turning, the steering angle ratio is unlikely to change with respect to changes in vehicle speed. Therefore, the rotation angle of the turning wheels is unlikely to change with respect to changes in vehicle speed. Thus, when the steering wheel is held at a constant steering angle or when the vehicle is turning, unintended vehicle behavior when vehicle speed changes can be suppressed.

[0014] In the steering control device, a first processor can be configured to calculate a target rotation angle of an axle that rotates with the turning of the steering wheel based on the vehicle speed and the steering angle of the steering wheel, and control the steering motor to achieve the target rotation angle of the axle. A second processor can be configured to fix the vehicle speed value used to calculate the target rotation angle when the steering wheel is held at a constant steering angle relative to the neutral position or when the vehicle is turning.

[0015] With this configuration, the vehicle speed value used to calculate the target rotation angle is fixed when the steering wheel is held at a constant steering angle or when the vehicle is turning. Therefore, it prevents the steering angle ratio from changing relative to actual vehicle speed.

[0016] In the steering control device, a first processor can be configured to calculate a target rotation angle of an axle that rotates with the turning of the steering wheel based on the steering angle of the steering wheel and the vehicle speed, and control the steering motor to achieve the target rotation angle of the axle. A second processor can be configured to limit the change in vehicle speed per unit time used to calculate the target rotation angle when the steering wheel is held at a constant steering angle relative to the neutral position or when the vehicle is turning.

[0017] With this configuration, the change in vehicle speed per unit time used to calculate the target rotation angle is limited when the steering wheel is held at a constant steering angle or when the vehicle is turning. Therefore, the degree of change in the steering angle ratio relative to the actual change in vehicle speed can be slowed down.

[0018] In the steering control device, a first processor can be configured to calculate a target rotation angle of the shaft by multiplying the steering angle of the steering wheel by a growth rate ratio between the steering wheel and the shaft rotating as the wheel rotates, calculated based on the vehicle speed, and to control a rotation motor to achieve the target rotation angle. A second processor can be configured to limit the variation of the growth rate ratio used to calculate the target rotation angle per unit time when the steering wheel is held at a constant steering angle relative to a neutral position or when the vehicle is rotating.

[0019] According to this configuration, the change per unit time in the rate of increase used to calculate the target rotation angle is limited when the steering wheel is held at a constant steering angle or when the vehicle is turning. Therefore, the degree of change in the steering angle ratio relative to the actual change in vehicle speed can be slowed down.

[0020] In the steering control device, a first processor can be configured to calculate a target rotation angle of an axle that rotates with the turning of the steering wheel based on the vehicle speed and the steering angle of the steering wheel, and control the steering motor to achieve the target rotation angle of the axle. A second processor can be configured to fix the value of the target rotation angle used to control the steering motor when the steering wheel is held at a constant steering angle relative to the neutral position or when the vehicle is turning.

[0021] With this configuration, the target rotation angle used to control the steering motor is fixed when the steering wheel is held at a constant steering angle or when the vehicle is turning. Therefore, it prevents the steering angle ratio from changing relative to actual vehicle speed.

[0022] In the steering control device, the second processor can be configured to slowly change the value of the vehicle speed used to calculate the target rotation angle to the current value of the vehicle speed detected by the vehicle speed sensor when the state of holding the steering wheel is released or when the rotation state of the vehicle is released.

[0023] According to this configuration, when the steering angle ratio returns to its original value based on the current vehicle speed, rapid changes in the steering angle ratio can be suppressed. Therefore, vehicle behavior unintentional to the driver can be suppressed.

[0024] In the steering control device, the second processor can be configured to slowly change the value of the growth rate used to calculate the target rotation angle to the current value of the growth rate calculated by the first processor when the state in which the steering wheel is held is released or when the rotation state of the vehicle is released.

[0025] According to this configuration, when the steering angle ratio returns to its original value based on the current vehicle speed, rapid changes in the steering angle ratio can be suppressed. Therefore, vehicle behavior unintentional to the driver can be suppressed.

[0026] In the steering control device, the second processor can be configured to slowly change the value of the target rotation angle used to control the steering motor to the current value of the target rotation angle calculated by the first processor when the state of holding the steering wheel is released or when the rotation state of the vehicle is released.

[0027] According to this configuration, when the steering angle ratio returns to its original value based on the current vehicle speed, rapid changes in the steering angle ratio can be suppressed. Therefore, vehicle behavior unintentional to the driver can be suppressed.

[0028] The steering control device may further include: a third processor configured to convert the rotation angle of an axis that rotates with the rotation of the wheels into a target steering angle of the steering wheel based on a steering angle ratio according to the vehicle speed, the steering angle ratio being the ratio of the rotation angle of the wheels to the steering angle of the steering wheel; and a fourth processor configured to change the degree of change of the steering angle ratio relative to the change in vehicle speed used to calculate the target steering angle by performing the same processing as performed by the second processor.

[0029] According to this configuration, the steering angle of the steering wheel and the rotation angle of the turning wheels can be synchronized with each other. In the steering control device, the rotation angle of the shaft used to calculate the target steering angle in the third processor can be at least one of the following: the rotation angle of the shaft when it is determined that the turning wheels of the vehicle are in contact with an obstacle; the rotation angle of the shaft when the vehicle is powered on; and the target rotation angle of the shaft generated when the main control device installed in the vehicle intervenes in the steering control.

[0030] According to the present invention, changes in vehicle behavior not intended by the driver can be suppressed. Attached Figure Description

[0031] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which similar reference numerals denote similar elements, and in the drawings:

[0032] Figure 1 This is a diagram showing the configuration of a steer-by-wire system equipped with a steering control device according to the first embodiment;

[0033] Figure 2 This is a block diagram showing the control device according to the first embodiment;

[0034] Figure 3 It is a graph showing the relationship between the steering angle and the target pinion angle based on the vehicle speed, according to the first embodiment.

[0035] Figure 4 This is a block diagram showing the target pinion angle calculation unit according to the first embodiment;

[0036] Figure 5 This is a block diagram showing the steering determination unit according to the first embodiment;

[0037] Figure 6 This is a block diagram showing the modified vehicle speed calculation unit according to the first embodiment;

[0038] Figure 7 This is a block diagram showing the upper limit calculation unit and the lower limit calculation unit according to the first embodiment;

[0039] Figure 8 This is a diagram schematically illustrating the behavior of a vehicle equipped with a steering control device according to the first embodiment;

[0040] Figure 9 This is a block diagram showing the main parts of the control device according to the second embodiment;

[0041] Figure 10 This is a block diagram showing the target pinion angle calculation unit according to the third embodiment;

[0042] Figure 11 This is a block diagram showing the correction processing unit according to the fourth embodiment;

[0043] Figure 12 This is a block diagram showing the rotation determination unit according to the fourth embodiment;

[0044] Figure 13 This is a block diagram showing the deceleration determination unit according to the fourth embodiment;

[0045] Figure 14 This is a block diagram showing the acceleration determination unit according to the fourth embodiment;

[0046] Figure 15 This is a block diagram showing the rotation determination unit according to the fifth embodiment;

[0047] Figure 16 This is a block diagram showing the rotation determination unit according to the sixth embodiment;

[0048] Figure 17 This is a block diagram showing the deceleration determination unit according to the sixth embodiment;

[0049] Figure 18 This is a block diagram showing the acceleration determination unit according to the sixth embodiment;

[0050] Figure 19 This is a perspective view of a wheel indicating the axial component of the tire force according to the sixth embodiment.

[0051] Figure 20 This is a block diagram showing the target pinion angle calculation unit according to the seventh embodiment;

[0052] Figure 21 This is a block diagram showing the steering reaction force command value calculation unit according to the eighth embodiment;

[0053] Figure 22 This is a block diagram showing the axial force calculation unit for the curbstone according to the eighth embodiment;

[0054] Figure 23It is a graph showing the relationship between the pinion angle and the target steering angle when in contact with the curb according to the eighth embodiment.

[0055] Figure 24 This is a block diagram showing the axial force calculation unit for the curbstone according to the eighth embodiment;

[0056] Figure 25 This is a block diagram showing the steering reaction force command value calculation unit according to the ninth embodiment;

[0057] Figure 26 It is a graph showing the relationship between the pinion angle and the target steering angle based on vehicle speed, according to the ninth embodiment.

[0058] Figure 27 This is a block diagram showing the control device according to the tenth embodiment;

[0059] Figure 28 This is a graph illustrating the relationship between a target pinion angle (additional angle) and a target steering angle (additional angle) used when performing an autonomous driving function according to the tenth embodiment; and

[0060] Figure 29 This is a block diagram showing the steering reaction force command value calculation unit according to the tenth embodiment. Detailed Implementation

[0061] First Implementation Method

[0062] The following describes a first embodiment of the steering control device applied to a steer-by-wire system.

[0063] like Figure 1 As shown, the vehicle's steering system 10 includes a steering shaft 12 connected to a steering wheel 11. The steering system 10 includes a steering shaft 12 along the vehicle's width direction (along...). Figure 1 A rotating shaft 14 extends in the left-right direction. Right and left rotating wheels 16 are connected to the two ends of the rotating shaft 14 via tie rods 15 and 16. When the rotating shaft 14 moves linearly, the rotation angle θ of the rotating wheels 16 and 16... w Change. Steering shaft 12 and rotating shaft 14 constitute the vehicle's steering mechanism.

[0064] The steering system 10 includes a reaction motor 31, a reduction gear mechanism 32, a rotation angle sensor 33, and a torque sensor 34 as a configuration for generating steering reaction force. The steering reaction force is a force acting in the opposite direction to the direction of operation of the steering wheel 11 operated by the driver. Applying a steering reaction force to the steering wheel 11 can provide the driver with an appropriate responsiveness.

[0065] The reaction motor 31 is the source of the steering reaction force. For example, a three-phase brushless motor can be used as the reaction motor 31. The reaction motor 31 (more precisely, its rotation shaft) is connected to the steering shaft 12 via a reduction gear mechanism 32. The torque of the reaction motor 31 is applied to the steering shaft 12 as the steering reaction force.

[0066] A rotation angle sensor 33 is installed in the reaction motor 31. The rotation angle sensor 33 detects the rotation angle θ of the reaction motor 31. a The rotation angle θ of the reaction motor 31 a Used to calculate steering angle θ s The reaction motor 31 and the steering shaft 12 are interlocked via a reduction gear mechanism 32. Therefore, the rotation angle θ of the reaction motor 31... a The rotation angle relative to the steering shaft 12—that is, the steering angle θ, which is the rotation angle of the steering wheel 11. s —There is a correlation between them. Therefore, it can be based on the rotation angle θ of the reaction motor 31. a To calculate the steering angle θ s .

[0067] Torque sensor 34 detects the steering torque T as the torque applied to steering shaft 12 by the rotational operation of steering wheel 11. h The torque sensor 34 detects the steering torque T applied to the steering shaft 12 based on the amount of torsion of a torsion bar located in the middle of the steering shaft 12. h The torque sensor 34 is located on the steering wheel 11 side of the reduction gear mechanism 32 in the steering shaft 12.

[0068] The steering system 10 includes a rotary motor 41, a reduction gear mechanism 42, and a rotation angle sensor 43 as a configuration for generating a rotational force, which is the power used to rotate the rotating wheels 16 and 16.

[0069] The rotary motor 41 is the source of rotational force. For example, a three-phase brushless motor is used as the rotary motor 41. The rotating shaft of the rotary motor 41 is connected to the pinion shaft 44 via a reduction gear mechanism 42. The pinion gear teeth 44a of the pinion shaft 44 mesh with the rack teeth 14b of the rotating shaft 14. The torque of the rotary motor 41 is applied as rotational force to the rotating shaft 14 via the pinion shaft 44. As the rotary motor 41 rotates, the rotating shaft 14 moves along the rotational force. Figure 1 The vehicle moves in the width direction, either left or right.

[0070] A rotation angle sensor 43 is installed in the rotary motor 41. The rotation angle sensor 43 detects the rotation angle θ of the rotary motor 41. bThe steering system 10 includes a pinion shaft 13. The pinion shaft 13 is configured to intersect with the rotating shaft 14. The pinion teeth 13a of the pinion shaft 13 mesh with the rack teeth 14a of the rotating shaft 14. The pinion shaft 13 is provided so that the rotating shaft 14 and the pinion shaft 44 are supported together in a housing (not shown). That is, the rotating shaft 14 is supported by a support mechanism (not shown) provided in the steering system 10 so that it can move axially and is pressed against the pinion shafts 13 and 44. Therefore, the rotating shaft 14 is supported in the housing. Another support mechanism can be provided to support the rotating shaft 14 in the housing without using the pinion shaft 13.

[0071] The steering system 10 includes a control unit 50. The control unit 50 controls the reaction motor 31 and the rotation motor 41 based on detection results from various sensors located in the vehicle. Examples of the various sensors, in addition to the rotation angle sensor 33, torque sensor 34, and rotation angle sensor 43, include a vehicle speed sensor 501. The vehicle speed sensor 501 detects the vehicle speed V, which is the vehicle's travel speed.

[0072] Control device 50 performs reaction control, thereby generating a steering torque T based on the drive control of reaction motor 31. h The steering reaction force. Control device 50 is based on steering torque T. h The target steering reaction force is calculated based on the vehicle speed V, and a steering reaction force command value is calculated based on the calculated target steering reaction force. The control device 50 supplies the current required to generate the steering reaction force corresponding to the steering reaction force command value to the reaction motor 31.

[0073] Control device 50 performs rotation control, causing rotating wheels 16 and 16 to rotate according to the direction of rotation via drive control of rotating motor 41. Control device 50 bases its control on the rotation angle θ of rotating motor 41 detected by rotation angle sensor 43. b To calculate the pinion angle θ, which is the actual rotation angle of the pinion shaft 44. p pinion angle θ p It reflects the rotation angle θ of rotating wheels 16 and 16. w The value of the control device 50 is based on the rotation angle θ of the reaction motor 31 detected by the rotation angle sensor 33. a To calculate the steering angle θ s And based on the calculated steering angle θ s To calculate the angle θ of the pinion. p The target value is the target pinion angle. Control device 50 calculates the target pinion angle and the actual pinion angle θ. p The difference between them is offset by controlling the power supply to the rotating motor 41 so that the difference is canceled out.

[0074] The control device 50 will now be described in detail. Figure 2 As shown, the control device 50 includes a reaction control unit 50a that performs reaction control and a rotation control unit 50b that performs rotation control.

[0075] The reaction control unit 50a includes a steering angle calculation unit 51, a steering reaction force command value calculation unit 52, and a power supply control unit 53. The steering angle calculation unit 51 is based on the rotation angle θ of the reaction motor 31 detected by the rotation angle sensor 33. a To calculate the steering angle θ of steering wheel 11 s .

[0076] Steering reaction force command value calculation unit 52 is based on steering torque T h The steering reaction force command value T is calculated based on the vehicle speed V. * The steering reaction force command value calculation unit 52 calculates the steering reaction force command value T. * This causes its absolute value to change with the steering torque T. h The absolute value of V increases as the vehicle speed V decreases.

[0077] The power supply control unit 53 will coordinate with the steering reaction force command value T * The corresponding power supply is sent to the reaction motor 31. Specifically, the power supply control unit 53 is based on the steering reaction force command value T. * The current command value for the reaction motor 31 is calculated. The power supply control unit 53 uses a current sensor 54 installed in the power supply path for the reaction motor 31 to detect the actual current I generated in that power supply path. a The value of current I. a The value is the actual current supplied to the reaction motor 31. The power supply control unit 53 calculates the current command value and the actual current I. a The difference between the values ​​is controlled, and the power supply to the reaction motor 31 is adjusted to cancel out this difference. Therefore, the reaction motor 31 generates a steering reaction force command value T. * The corresponding torque. Therefore, the driver can be given an appropriate sense of response based on the road reaction force.

[0078] The rotation control unit 50b includes a pinion angle calculation unit 61, a target pinion angle calculation unit 62, a pinion angle feedback control unit 63, and a power supply control unit 64. The pinion angle calculation unit 61 is based on the rotation angle θ of the rotation motor 41 detected by the rotation angle sensor 43. b To calculate the pinion angle θ, which is the actual rotation angle of the pinion shaft 44. pThe rotating motor 41 and the pinion shaft 44 are interlocked via a reduction gear mechanism 42. Therefore, the rotation angle θ of the rotating motor 41... b Angle θ with the pinion p There is a correlation between them. The pinion angle θ p The correlation can be used based on the rotation angle θ of the rotating motor 41. b Calculation. The pinion shaft 44 meshes with the rotating shaft 14. Therefore, the pinion angle θ p There is also a correlation with the displacement of the rotating shaft 14. That is, the pinion angle θ p It reflects the rotation angle θ of rotating wheels 16 and 16. w The value of .

[0079] The target pinion angle calculation unit 62 is based on the steering angle θ calculated by the steering angle calculation unit 51. s The target pinion angle θ is calculated using the vehicle speed V detected by the vehicle speed sensor 501. p * For example, the target pinion angle calculation unit 62 is set as the rotation angle θ based on the vehicle speed V. w With steering angle θ s The ratio of the steering angles is used to calculate the target pinion angle θ based on the set steering angle ratio. p * The target pinion angle calculation unit 62 calculates the target pinion angle θ. p * This causes the rotation angle θ w relative to the steering angle θ s The angle θ increases as the vehicle speed V decreases, and the rotation angle θ increases as the vehicle speed V decreases. w relative to the steering angle θ s The value decreases as the vehicle speed V increases. To achieve the steering angle ratio set according to the vehicle speed V, the target pinion angle calculation unit 62 calculates the steering angle θ. s The correction angle is calculated by comparing the calculated correction angle with the steering angle θ, based on the steering angle ratio. s The target pinion angle θ is calculated by adding them together. p * .

[0080] In this embodiment, the target pinion angle calculation unit 62 uses mapping M1 to calculate the target pinion angle θ. p * Mapping M1 is stored in the storage device of control device 50. For example... Figure 3 As shown in the graph, mapping M1 is where the steering angle θ is limited according to the vehicle speed V. s Angle θ with the target pinion p* A three-dimensional mapping of the relationship between them. Mapping M1 has the following properties: that is, the target pinion angle θ p * The absolute value varies with the steering angle θ s The absolute value of V increases as the vehicle speed V decreases.

[0081] like Figure 2 As shown, the pinion angle feedback control unit 63 receives the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * and the actual pinion angle θ calculated by pinion angle calculation unit 61 p The pinion angle feedback control unit 63 uses the pinion angle θ p Feedback control is used to calculate the pinion angle command value T. p * This makes the actual pinion angle θ p Meets the target pinion angle θ p * .

[0082] The power supply control unit 64 will communicate with the pinion angle command value T p * The corresponding power supply is sent to the rotating motor 41. Specifically, the power supply control unit 64 is based on the pinion angle command value T. p * The power supply control unit 64 calculates the current command value for rotating motor 41. It uses a current sensor 65 located in the power supply path for rotating motor 41 to detect the actual current I generated in that power supply path. b The value of current I. b The value is the actual current supplied to the rotating motor 41. The power supply control unit 64 calculates the current command value and the actual current I. b The difference between the values ​​is controlled, and the power supply to the rotary motor 41 is adjusted to cancel out this difference. Therefore, the rotary motor 41 rotates in accordance with the pinion angle command value T. p * The corresponding angle.

[0083] Due to the basis Figure 3 The curve diagram shows the mapping M1, and the target pinion angle θ. p * relative to the steering angle θ s The target pinion angle θ changes according to the vehicle speed V. p * The absolute value varies with the steering angle θ s The absolute value of θ increases as the vehicle speed V decreases. That is, as a rotation angle θ...w With steering angle θ s The value of the steering angle ratio increases as the vehicle speed V increases and decreases as the vehicle speed V decreases.

[0084] As the steering angle ratio decreases, the rotation angle θ of wheels 16 and 16 decreases when steering wheel 11 is operated. w and θ w The steering angle ratio increases, allowing for faster changes. Therefore, for example, when the vehicle enters a garage at low speeds, a smaller steering input yields a larger rotation, thus ensuring vehicle maneuverability. As the steering angle ratio increases, the rotation angle θ of wheels 16 and 16 increases when the steering wheel 11 is operated. w and θ w The changes are made more slowly. Therefore, for example, when the vehicle changes lanes in a high-speed area, the driving stability of the vehicle is ensured.

[0085] Because the steering angle ratio changes according to the vehicle speed V, there is a concern that the vehicle may decelerate or accelerate while rotating. In this case, since the steering angle ratio changes with the vehicle speed V, the rotation angle θ of the rotating wheels 16 and 16 will also change. w and θ w It also changes with the vehicle speed V. Therefore, there is a concern that vehicle behavior may occur that is not intentional on the part of the driver.

[0086] For example, when a vehicle decelerates while rotating, the rotation angle θ w and θ w The angle changes significantly as the vehicle speed V decreases. Therefore, the vehicle's trajectory may change, causing the vehicle to move inwards relative to the driver's intended rotational trajectory. When the vehicle accelerates while rotating, the rotation angle θ... w and θ w The angle changes slightly as the vehicle speed V increases. As a result, the vehicle's trajectory changes, causing it to jut outward from the intended turning path of the driver.

[0087] Specifically, when the vehicle is held at a constant steering angle θ by steering wheel 11 s When the vehicle speed V changes while the steering wheel 11 is turned in a certain state, even if the steering wheel 11 remains at a constant steering angle θ, s The rotation angle θ of rotating wheels 16 and 16 w and θ w It also changes with the vehicle's speed V. Therefore, the driver is more likely to feel uncomfortable because they are not maintaining the intended driving trajectory.

[0088] Therefore, in this embodiment, the target pinion angle calculation unit 62 is configured as follows to suppress changes in vehicle behavior not intended by the driver. Figure 4 As shown, the target pinion angle calculation unit 62 includes a correction processing unit 70A and an angle calculation unit 70B.

[0089] The correction processing unit 70A corrects the vehicle speed V detected by the vehicle speed sensor 501 based on the steering state of the steering wheel 11. The correction processing unit 70A includes a differentiator 71, a steering determination unit 72, and a vehicle speed correction calculation unit 73.

[0090] Differentiator 71 processes the steering angle θ calculated by steering angle calculation unit 51. s The steering angular velocity ω is calculated by differentiation. The steering determination unit 72 receives the vehicle speed V detected by the vehicle speed sensor 501 and the steering angle θ calculated by the steering angle calculation unit 51. s And the steering angular velocity ω calculated by the differentiator 71, and based on the received vehicle speed V and steering angle θ s The steering angular velocity ω determines whether the steering wheel 11 is kept at a constant steering angle θ. s The term "steering hold" as used herein refers to the state in which the steering wheel 11 is held at a position that is turned to the right or left relative to a neutral position corresponding to the state of the vehicle's forward straight-line travel. The steering hold determination unit 72 sets the value of the flag F0 to indicate whether the steering state of the steering wheel 11 is a steering hold determination result. Details of the steering hold determination unit 72 will be described later.

[0091] The vehicle speed calculation unit 73 receives the vehicle speed V detected by the vehicle speed sensor 501 and the steering angle θ calculated by the steering angle calculation unit 51. s The vehicle speed calculation unit 73 calculates the steering angular velocity ω by the differentiator 71 and the value of the flag F0 set by the steering hold determination unit 72. The vehicle speed correction calculation unit 73 then calculates the vehicle speed V and steering angle θ. s The steering angular velocity ω and the value of the sign F0 are corrected by calculating the vehicle speed V detected by the vehicle speed sensor 501. c Details regarding the correction of vehicle speed calculation unit 73 will be described later.

[0092] Angle calculation unit 70B receives the steering angle θ calculated by steering angle calculation unit 51. s And the corrected vehicle speed V, which is the vehicle speed V corrected by the correction processing unit 70A. c Angle calculation unit 70B is used. Figure 3The target pinion angle θ is calculated using the mapping M1 shown in the curve diagram. p * .

[0093] The configuration of the steering determination unit 72 will be described in detail below. Figure 5 As shown, the steering determination unit 72 includes two threshold calculation units 72A and 72B and three determination units 72C, 72D and 72E.

[0094] Threshold calculation unit 72A calculates the steering angular velocity threshold ω based on the vehicle speed V. th The threshold calculation unit 72A uses the mapping M2 stored in the storage device of the control device 50 to calculate the steering angular velocity threshold ω. th Mapping M2 is a two-dimensional mapping—where the vehicle speed V is set for the horizontal axis and the steering angular velocity threshold ω is set for the vertical axis. th Furthermore, the mapping M2 limits the vehicle speed V to the steering angular velocity threshold ω. th The relationship between them. For example, mapping M2 has the following characteristics: that is, the steering angular velocity threshold ω th It is set to decrease as the vehicle speed V increases.

[0095] Threshold calculation unit 72B calculates the steering angle threshold θ based on the vehicle speed V. sth The threshold calculation unit 72B uses the mapping M3 stored in the storage device of the control device 50 to calculate the steering angle threshold θ. sth Mapping M3 is a two-dimensional mapping—where the vehicle speed V is set for the horizontal axis and the steering angle threshold θ is set for the vertical axis. sth Furthermore, the mapping M3 limits the vehicle speed V to the steering angle threshold θ. sth The relationship between them. For example, mapping M3 has the following properties: that is, the steering angle threshold θ sth It is set to decrease as the vehicle speed V increases.

[0096] Unit 72C determines the absolute value of the steering angular velocity ω by comparing it with the steering angular velocity threshold ω. th A comparison is made to determine whether the steering state of steering wheel 11 is maintained. When the absolute value of the steering angular velocity ω is less than the steering angular velocity threshold ω... th When the steering wheel 11 is determined to be in a holding steering state, the determining unit 72C sets the value of flag F1 based on the determination result indicating whether the steering wheel 11 is in a holding steering state. When the steering wheel 11 is determined to be in a holding steering state, the determining unit 72C sets the value of flag F1 to "1". When the steering wheel 11 is determined to be in a holding steering state, the determining unit 72C sets the value of flag F1 to "0".

[0097] The unit 72D determines the steering angle θ by... s The absolute value and the steering angle threshold θ sth A comparison is made to determine whether the steering wheel 11 remains at a position deviating from the neutral position corresponding to the vehicle's straight forward movement. When the steering angle θ... s The absolute value is greater than the steering angle threshold θ sth When the steering wheel 11 is determined to be in a position deviating from the neutral position, the determination unit 72D sets the value of flag F2 based on the determination result indicating whether the steering wheel 11 is in a position deviating from the neutral position. When it is determined that the steering wheel 11 is in a position deviating from the neutral position, the determination unit 72D sets the value of flag F2 to "1". When it is determined that the steering wheel 11 is not in a position deviating from the neutral position, the determination unit 72D sets the value of flag F2 to "0".

[0098] Based on the value of flag F1 set by determination unit 72C and the value of flag F2 set by determination unit 72D, determination unit 72E sets the value of flag F0 to the result of maintaining steering. When both flags F1 and F2 are "1", determination unit 72E sets the value of flag F0, which indicates that the steering wheel 11 is maintained at a position deviating from the neutral position, to "1". When at least one of the two flags F1 and F2 is "0", determination unit 72E sets the value of flag F0, which indicates that the steering wheel 11 is not maintained at a position deviating from the neutral position, to "0".

[0099] The configuration of the corrected vehicle speed calculation unit 73 will be described in detail below. For example... Figure 6 As shown, the vehicle speed calculation unit 73 includes a determination unit 73A, a previous value storage unit 73B, a switch 73C, an upper limit value calculation unit 73D, a lower limit value calculation unit 73E, a previous value storage unit 73F, a determination unit 73G, and a protection processing unit 73H.

[0100] The determining unit 73A receives the value of the flag F0 set by the holding steering determining unit 72, and sets an instruction for calculating the target pinion angle θ based on the received value of the flag F0. p * The value of the vehicle speed V is determined by the value of the indicator F3. When the value of indicator F0 is "1", that is, when the steering wheel 11 is held at a constant steering angle θ... s At that time, the determining unit 73A determines the angle θ of the target pinion used to calculate the angle. p *The vehicle speed V is constant, and the value of sign F3 is set to "1". When the value of sign F0 is "0", that is, when the steering wheel 11 is not maintained at a constant steering angle θ... s At that time, the determining unit 73A determines the angle θ of the target pinion used to calculate the angle. p * The vehicle speed V is not fixed, and the value of flag F3 is set to "0".

[0101] Previous value storage unit 73B receives the corrected vehicle speed V calculated by the protection processing unit 73H, which will be described later. c And store the received corrected vehicle speed V c The protection processing unit 73H calculates and corrects the vehicle speed V at predetermined operating cycle intervals. c And whenever the protection processing unit 73H calculates the corrected vehicle speed V c At that time, update the corrected vehicle speed V stored in the previous value storage unit 73B. c That is, the corrected vehicle speed V stored in the previous value storage unit 73B. c The corrected vehicle speed V is calculated by the protection processing unit 73H. c The previous value of the current value (the corrected vehicle speed V one operating cycle ago) c ).

[0102] Switch 73C receives the vehicle speed V detected by vehicle speed sensor 501 and the corrected vehicle speed V stored in the previous value storage unit 73B. c Previous value V cn-1 As data input, switch 73C receives the value of flag F3 set by determination unit 73A as control input. Switch 73C selects the vehicle speed V detected by vehicle speed sensor 501 and the corrected vehicle speed V stored in previous value storage unit 73B based on the value of flag F3. c Previous value V cn-1 One of them is used as the temporary vehicle speed value V temp When the value of flag F3 is "0", switch 73C selects the vehicle speed V detected by vehicle speed sensor 501 as the temporary vehicle speed value V. temp When the value of flag F3 is "1" (more precisely, when the value of flag F3 is not "0"), switch 73C selects to correct the vehicle speed V. c Previous value V cn-1 As a temporary vehicle speed value V temp .

[0103] When the steering wheel 11 is kept at a constant steering angle θ sWhen the state is maintained, the value of flag F3 is set to "1". During the period when the value of flag F3 is set to "1", the corrected vehicle speed V stored in the previous value storage unit 73B is maintained. c Previous value V cn-1 The temporary vehicle speed value V is usually selected. temp .

[0104] Switch 73C can receive the value of flag F0 set by steering hold determination unit 72 as a control input. When this configuration is used, a configuration in which determination unit 73A is omitted can be used as a vehicle speed calculation correction unit 73.

[0105] The upper limit calculation unit 73D receives the vehicle speed V detected by the vehicle speed sensor 501 and the steering angle θ calculated by the steering angle calculation unit 51. s And the steering angular velocity ω calculated by the differentiator 71, based on the vehicle speed V and the steering angle θ s And the steering angular velocity ω is used to calculate the temporary vehicle speed value V. temp The upper limit of the change V in each operating cycle UL Details of the upper limit calculation unit 73D will be described later.

[0106] The lower limit calculation unit 73E receives the vehicle speed V detected by the vehicle speed sensor 501 and the steering angle θ calculated by the steering angle calculation unit 51. s And the steering angular velocity ω calculated by the differentiator 71, and based on the received vehicle speed V and steering angle θ s And the steering angular velocity ω is used to calculate the temporary vehicle speed value V. temp The lower limit of the change in each operating cycle, V UL Details of the lower limit calculation unit 73E will be described later.

[0107] The previous value storage unit 73F receives the value of flag F4 set by the determination unit 73G (described later) and stores the received value of flag F4. The determination unit 73G sets the value of flag F4 at predetermined operating cycle intervals, and updates the value of flag F4 stored in the previous value storage unit 73F whenever the determination unit 73G sets the value of flag F4. That is, the value of flag F4 stored in the previous value storage unit 73F is the previous value of flag F4 (the value of flag F4 one operating cycle ago) that serves as the current value set by the determination unit 73G.

[0108] Unit 73G determines whether to limit the corrected vehicle speed V. cThe determination unit 73G receives the value of flag F4 set by the determination unit 73A and the corrected vehicle speed V stored in the previous value storage unit 73B, and records the changes in each operating cycle. c Previous value V cn-1 The temporary vehicle speed value V selected by switch 73C temp and the previous value F4 of the flag F4 stored in the previous value storage unit 73F. n-1 The determination unit 73G adjusts the vehicle speed V based on the value of flag F3. c Previous value V cn-1 Temporary vehicle speed value V temp And the previous value F4 of the flag F4 n-1 To set the value of flag F4, follow these steps.

[0109] When the value of flag F3 set by determining unit 73A changes from "1" to "0", that is, when steering wheel 11 is maintained at a constant steering angle θ s When the state changes to the state where the steering wheel 11 is not maintained at a constant steering angle, the determination unit 73G sets the value of the flag F4 to "1".

[0110] Subsequently, when the following expression (A1) is satisfied, the determining unit 73G sets the value of flag F4 to "0". When the following expression (A1) is not satisfied, the determining unit 73G maintains the state in which the value of flag F4 is set to "1".

[0111] |V temp -V c |≤V th …(A1)

[0112] Here, "V" temp "V" is the temporary vehicle speed value selected by switch 73C, while "V" is... c "The corrected vehicle speed is calculated by the protection processing unit 73H." th "is the vehicle speed threshold, and is used to determine the vehicle speed V detected by the vehicle speed sensor and the corrected vehicle speed V." c Is the difference between them a baseline value that is small enough? Vehicle speed threshold V th The setting is based on the following viewpoint: when the steering state of the steering wheel 11 changes from a steering hold state to a non-steering hold state, the target pinion angle θ is suppressed based on the difference between the fixed vehicle speed and the actual vehicle speed. p * Rapid changes.

[0113] In addition, when the value of flag F3 does not change from "1" to "0", that is, when the value of flag F3 is "0" and when the value of flag F3 changes from "0" to "1", the determining unit 73G sets the value of flag F4 to "0".

[0114] The protection processing unit 73H switches between active and inactive for the temporary vehicle speed value V selected by the switch 73C based on the value of the flag F4 set by the determination unit 73G. temp The restriction processing function. When the value of flag F4 is set to "1", that is, when the steering wheel 11 is released from the holding steering state, the protection processing unit 73H enables the temporary vehicle speed value V. temp The limitation processing function is effective. The protection processing unit 73H uses the upper limit value V. UL and lower limit value V LL To limit the temporary vehicle speed value V temp The changes occur in each operating cycle. This operation is performed as follows.

[0115] That is, when the temporary vehicle speed value V temp The change in each operating cycle is greater than the upper limit value V UL At that time, the temporary vehicle speed value V temp The variation in each operating cycle is limited to an upper limit value V. UL It has been changed to correspond to the value V that is limited to the upper limit. UL The change in temporary vehicle speed value V temp Calculated as the corrected vehicle speed V c When the temporary vehicle speed value V temp The change in each operating cycle is less than the lower limit value V LL At that time, the temporary vehicle speed value V temp The variation in each operating cycle is limited to a lower limit value V. LL It has been changed to correspond to the value V that is restricted to the lower limit. LL The change in temporary vehicle speed value V temp Calculated as the corrected vehicle speed V c In this way, the temporary vehicle speed value V temp The maximum and minimum changes are determined by the upper limit value V. UL and lower limit value V LL Sure.

[0116] When the value of flag F4 is set to "0", the protection processing unit 73H enables the temporary vehicle speed value V. temp The restriction processing function is invalid. That is, the temporary vehicle speed value V selected by switch 73C is invalid. temp Calculated as the corrected vehicle speed V c Without any changes required.

[0117] The upper limit calculation unit 73D will be described in detail below. For example... Figure 7 As shown, the upper limit calculation unit 73D includes two limit value calculation units 81A and 81B, two gain calculation units 82A and 82B, two multipliers 83A and 83B, and a selection processing unit 84.

[0118] Limit value calculation unit 81A calculates the limit value V based on the steering angular velocity ω calculated by differentiator 71. a The limit value calculation unit 81A uses the mapping M4 stored in the storage device of the control device 50 to calculate the limit value V. a Mapping M4 defines the absolute value and limit value V of the steering angular velocity ω. a A two-dimensional mapping of the relationship between them, and with the following properties: That is, as the absolute value of the steering angular velocity ω increases, the limiting value V... a The value increases. Furthermore, mapping M4 is set based on the idea that when the absolute value of the steering angular velocity ω increases, it will be used to calculate the target pinion angle θ. p * The vehicle speed or steering angle ratio value returns to the true value more quickly without undergoing the process of correcting the vehicle speed.

[0119] The gain calculation unit 82A calculates the gain G based on the vehicle speed V detected by the vehicle speed sensor 501. a The gain calculation unit 82A uses the mapping M5 stored in the storage device of the control device 50 to calculate the gain G. a Mapping M5 limits the vehicle speed V and the gain G. a A two-dimensional mapping of the relationship between them, and with the following property: That is, when the vehicle speed V has a value near "0" in the extremely low speed region, the gain G... a The value of increases rapidly with increasing vehicle speed V. When the vehicle speed V exceeds the value in the extremely low speed region, the gain G... a The value of increases slowly as the vehicle speed V increases.

[0120] Multiplier 83A multiplies the limit value V calculated by limit value calculation unit 81A. a Multiply by the gain G calculated by the gain calculation unit 82A a To calculate the previous limit value V A The limit value calculation unit 81B is based on the steering angle θ calculated by the steering angle calculation unit 51. s To calculate the limit value V b The limit value calculation unit 81B uses the mapping M6 stored in the storage device of the control device 50 to calculate the limit value V. b The mapping M6 limits the steering angle θ. sThe absolute value and limit value V b A two-dimensional mapping of the relationship between them, and it has the following properties. That is, with the turning angle θ s As the absolute value increases, the limit value V b The value decreases slowly.

[0121] The gain calculation unit 82B calculates the gain G based on the vehicle speed V detected by the vehicle speed sensor 501. b The gain calculation unit 82B uses the mapping M7 stored in the storage device of the control device 50 to calculate the gain G. b Mapping M7 limits the vehicle speed V and gain G. b A two-dimensional mapping of the relationship between them, and with the following property: That is, as the vehicle speed V increases relative to "0", the gain G... b The value increases slowly. Mapping M7 is set based on the idea that as the vehicle speed V increases, it will be used to calculate the target pinion angle θ. p * The vehicle speed or steering angle ratio value returns to the true value more quickly without undergoing the process of correcting the vehicle speed.

[0122] Multiplier 83B multiplies the limit value V calculated by limit value calculation unit 81B. b Multiply by the gain G calculated by the gain calculation unit 82B b To calculate the previous limit value V B The selection processing unit 84 selects the preceding limit value V calculated by the multiplier 83A. A and the preceding limit value V calculated by multiplier 83B B Comparison to calculate the upper limit value V UL .

[0123] Current limit value V A Equal to or less than the previous limit value V B At that time, the selection processing unit 84 selects the previous limit value V. B As the upper limit value V UL As represented by the following expression (A2). In this case, except when the vehicle speed V is "0", the angle θ of the target pinion will be used to calculate the angle θ as time progresses. p * The vehicle speed or steering angle ratio slowly returns to the true value without undergoing the process of correcting the vehicle speed.

[0124] V A ≤V B →V UL =V B …(A2)

[0125] Current limit value VA Greater than the previous limit value V B At that time, the selection processing unit 84 selects the previous limit value V. A As the upper limit value V UL As represented by the following expression (A3). In this case, except when the vehicle speed V is "0", as time passes, the target pinion angle θ will be calculated based on the steering angular velocity ω. p * The vehicle speed or steering angle ratio slowly returns to the true value without undergoing the process of correcting the vehicle speed.

[0126] V A >V B →V UL =V A …(A3)

[0127] The lower limit calculation unit 73E will now be described in detail. The lower limit calculation unit 73E has the same configuration as the upper limit calculation unit 73D. That is, as... Figure 7 As described in square brackets, the lower limit calculation unit 73E includes two limit calculation units 91A and 91B, two gain calculation units 92A and 92B, two multipliers 93A and 93B, and a selection processing unit 94.

[0128] Limit value calculation unit 91A calculates the limit value V based on the steering angular velocity ω calculated by differentiator 71. a The gain calculation unit 92A calculates the gain G based on the vehicle speed V detected by the vehicle speed sensor 501. a The multiplier 93A uses the limit value V calculated by the limit value calculation unit 91A. a Multiply by the gain G calculated by the gain calculation unit 92A a To calculate the previous limit value V A .

[0129] Limit value calculation unit 91B is based on the steering angle θ calculated by steering angle calculation unit 51. s To calculate the limit value V b The gain calculation unit 92B calculates the gain G based on the vehicle speed V detected by the vehicle speed sensor 501. b The multiplier 93B uses the limit value V calculated by the limit value calculation unit 91B. b Multiply by the gain G calculated by the gain calculation unit 92B b To calculate the previous limit value V B .

[0130] Current limit value V A Equal to or less than the previous limit value V BAt that time, the selection processing unit 94 selects the previous limit value V. B As the lower limit value V LL As represented by the following expression (A4). Current limit value V A Greater than the previous limit value V B At that time, the selection processing unit 94 selects the previous limit value V. A As the lower limit value V LL , as represented by the following expression (A5).

[0131] V A ≤V B →V LL =V B …(A4)

[0132] V A >V B →V UL =V A …(A5)

[0133] The operation in the first embodiment will now be described.

[0134] When the vehicle is traveling straight forward with the steering wheel 11 in a neutral position, the determining unit 73A sets the value of the flag F3 to "0" (see...). Figure 6 Therefore, during the period when the vehicle is traveling straight forward, the vehicle speed V detected by the vehicle speed sensor 501 is usually selected by the switch 73C as the temporary vehicle speed value V. temp When the value of flag F3 is "0", the determining unit 73G sets the value of flag F4 to "0". Therefore, the protection processing unit 73H determines the value of the temporary vehicle speed V. temp The limiting processing function is invalid. Therefore, the vehicle speed V detected by the vehicle speed sensor 501 is usually calculated as the corrected vehicle speed V. c That is, when the vehicle is traveling forward in a straight line, the target pinion angle θ is calculated using the vehicle speed V detected by the vehicle speed sensor 501. p * Here, when the steering wheel 11 is held in the neutral position (steering angle θ) s When θ = 0°, the target pinion angle θ p * Set to the neutral position corresponding to the rotation axis 14 (rotation angle θ) w The "0°" is independent of the vehicle speed V. Therefore, even when the vehicle speed V changes as the vehicle decelerates or accelerates, the driver will not feel discomfort.

[0135] When the vehicle is turned while the steering wheel 11 is being turned, the determining unit 73A sets the value of the flag F3 to "0". Therefore, during the period when the steering wheel 11 is being turned, the vehicle speed V detected by the vehicle speed sensor 501 is selected by the switch 73C as the temporary vehicle speed value V. temp When the value of flag F3 is "0", the determining unit 73G sets the value of flag F4 to "0". Therefore, the protection processing unit 73H determines the value of the temporary vehicle speed V. temp The limiting processing function is invalid. Therefore, the vehicle speed V detected by the vehicle speed sensor 501 is usually calculated as the corrected vehicle speed V. c That is, the target pinion angle θ is calculated using the vehicle speed V detected by the vehicle speed sensor 501. p * Therefore, the target pinion angle θ p * The value of the steering angle ratio changes with the vehicle speed V caused by deceleration or acceleration. When the steering wheel 11 is turned, the vehicle's travel path changes with the steering angle θ. s The steering wheel 11 changes from time to time. Therefore, even when the steering wheel 11 is turned and the steering angle ratio changes slightly with the change of vehicle speed V, the driver is unlikely to be aware of this and is unlikely to feel uncomfortable.

[0136] When the vehicle is held at a constant steering angle θ by steering wheel 11 s When the vehicle is turned while the steering wheel 11 is in the specified state, the value of the flag F3 is set to "1". Therefore, during the period when the vehicle is turned while the steering wheel 11 is in the specified state, the corrected vehicle speed V stored in the previous value storage unit 73B is... c Previous value V cn-1 It is usually chosen as the temporary vehicle speed value V temp When the vehicle is turned while the steering wheel 11 is in the same position, the determination unit 73G sets the value of flag F4 to "1". Here, the restriction processing function of the protection processing unit 73H remains in an invalid state.

[0137] Therefore, the corrected vehicle speed V stored in the previous value storage unit 73B c Previous value V cn-1 It is usually calculated as the corrected vehicle speed V. c That is, regardless of the actual vehicle speed V detected by the vehicle speed sensor 501, it is used as the parameter for calculating the target pinion angle θ. p * The final vehicle speed correction vehicle speed V c The value will not change. Therefore, when the vehicle is turned while the steering wheel 11 is in its current state, even if the vehicle begins to decelerate or accelerate, the target pinion angle θ will remain unchanged.p * The value of the steering angle ratio will not change.

[0138] That is, such as Figure 8 As shown in the left part, when the vehicle is held at a constant steering angle θ by steering wheel 11. s When the vehicle is turned (in this case, a left turn) and begins to decelerate, it travels along the intended turning trajectory L1. Therefore, the driver will not experience any discomfort.

[0139] When used to calculate the target pinion angle θ p * When the vehicle speed is not constant, the target pinion angle θ p * The angle increases as the vehicle speed decreases, and therefore the vehicle's actual driving trajectory L2 changes, causing the vehicle to move inward relative to the driver's intended turning trajectory L1. In this respect, according to this embodiment, when the vehicle is held at a constant steering angle θ by the steering wheel 11... s When rotating in this state, it will be used to calculate the target pinion angle θ. p * The vehicle speed is fixed at the value when the steering state of the steering wheel 11 is determined to be the vehicle speed when the steering state is maintained, and thus the inward movement of the vehicle is suppressed.

[0140] That is, such as Figure 8 As shown on the right side, when the vehicle is held at a constant steering angle θ by steering wheel 11. s When the vehicle is turned (in this case, a left turn) and begins to accelerate, it travels along the intended turning trajectory L1. Therefore, the driver will not experience any discomfort.

[0141] When used to calculate the target pinion angle θ p * When the vehicle speed is not constant, the target pinion angle θ p * The angle decreases as vehicle speed increases, and therefore the vehicle's actual driving trajectory L2 changes, causing it to protrude outward from the driver's intended turning trajectory L1. In this respect, according to this embodiment, when the vehicle is held at a constant steering angle θ by the steering wheel 11... s When rotating in this state, it will be used to calculate the target pinion angle θ. p * The vehicle speed is fixed at the value when the steering state of the steering wheel 11 is determined to be the vehicle speed when the steering state is maintained, and thus the vehicle protrusion is suppressed.

[0142] When the vehicle is held at a constant steering angle θ by steering wheel 11 sWhen the steering wheel 11 is turned and steering resumes, the determining unit 73A sets the value of flag F3 to "0". Therefore, after steering resumes, the vehicle speed V detected by vehicle speed sensor 501 is selected by switch 73C as the temporary vehicle speed value V. temp When the value of flag F3 changes from "1" to "0", the determining unit 73G sets the value of flag F4 to "1". Therefore, the protection processing unit 73H determines the value of the temporary vehicle speed V. temp The limitation processing function is effective. Therefore, it is used to calculate the target pinion angle θ. p * Temporary vehicle speed value V temp Or correct the vehicle speed V c The variation in each operating cycle is limited to an upper limit value V. UL Or lower limit value V LL .

[0143] Here, one can imagine the temporary vehicle speed value V immediately before the steering wheel 11 restarts. temp The vehicle speed used (i.e., the corrected vehicle speed V stored in the previous value storage unit 73B when it is determined that the steering wheel 11 is in a steering state) c The vehicle speed V immediately after steering has resumed (as indicated by the steering wheel 11) and the vehicle speed V immediately after steering has resumed (as indicated by the steering wheel 11) are different. In this case, the target pinion angle θ is based on the vehicle speed immediately before steering resumes (as indicated by the steering wheel 11). p * And the target pinion angle θ based on the vehicle speed immediately after steering has resumed on steering wheel 11. p * They are also different from each other. Therefore, when the vehicle speed V is immediately used immediately after the steering wheel 11 has restarted, the target pinion angle θ p * Or the rotation angle θ of the rotating wheel 16 w It can change rapidly.

[0144] In this respect, according to this embodiment, when the steering wheel 11 has resumed steering, the temporary vehicle speed value V temp The changes (maximum and minimum changes) in each operating cycle are limited to an upper limit value V. UL Or lower limit value V LL Therefore, it is possible to suppress the use of the angle θ of the target pinion as a metric for calculating the pinion angle. p * The final vehicle speed correction vehicle speed V c Rapid changes in the value of V. Correction for vehicle speed V. cThe values ​​depend on the vehicle's steering state (here, steering angular velocity ω and steering angle θ). s The vehicle speed (V) or driving state (in this case, vehicle speed V) slowly changes over time to the value of vehicle speed V detected by vehicle speed sensor 501. Therefore, the target pinion angle θ can be suppressed. p * Or rotation angle θ w Rapid changes.

[0145] When the temporary vehicle speed value V temp (Here, the vehicle speed V detected by vehicle speed sensor 501) and the angle θ used to calculate the target pinion. p * The final vehicle speed correction vehicle speed V c The absolute value of the difference between them becomes equal to or less than the vehicle speed threshold V. th At that time, the determining unit 73G sets the value of flag F4 to "0". Therefore, the protection processing unit 73H determines the value of temporary vehicle speed V. temp The limitation processing function is invalid. Therefore, the vehicle speed V detected by the vehicle speed sensor 501 is used as the corrected vehicle speed V. c To calculate the target pinion angle θ p * And without any changes. That is, based on the steering angle θ s To calculate a more suitable target pinion angle θ based on the actual vehicle speed V. p * .

[0146] Therefore, according to the first embodiment, the following advantages can be obtained. When the vehicle is held at a constant steering angle θ by the steering wheel 11... s (where, |θ) s When rotating in the state of |>0), it will be used to calculate the target pinion angle θ. p * The final vehicle speed correction vehicle speed V c The vehicle speed is fixed immediately prior to determining that the steering state of the steering wheel 11 is rotation and maintaining the steering state. That is, regardless of the actual value of the vehicle speed V, when the steering state of the steering wheel 11 is determined to be rotation and maintaining the steering state, the target pinion angle θ is... p * Maintain at the same angle as the steering angle θ s The corresponding value. Therefore, even when the vehicle is held at a constant steering angle θ by steering wheel 11. s When the vehicle speed V changes during rotation in the specified state, the rotation angle θ of rotating wheels 16 and 16... w and θ wOr the steering angle ratio will not change with the vehicle speed V.

[0147] Therefore, when the vehicle is kept at a constant steering angle θ by the steering wheel 11 s When the vehicle decelerates while the steering wheel 11 is in the desired state, it prevents the vehicle's actual driving trajectory L2 from changing inward relative to the driver's intended turning trajectory L1. When the vehicle accelerates while the steering wheel 11 is in the desired state, it prevents the vehicle's actual driving trajectory L2 from protruding outward from the driver's intended turning trajectory L1. Therefore, when the vehicle is in a constant steering angle θ while the steering wheel 11 is in the desired state, it prevents the vehicle's actual driving trajectory L2 from changing inward relative to the driver's intended turning trajectory L1. s When the vehicle speed changes while rotating in a certain state, it can suppress changes in vehicle behavior that are not intended by the driver.

[0148] When the vehicle is held at a constant steering angle θ by steering wheel 11 s When the steering wheel 11 restarts in the current state, the fixed vehicle speed value is released, and the target pinion angle θ is calculated using the actual vehicle speed V detected by the vehicle speed sensor 501. p * At this point, the target pinion angle θ is used for calculation. p * The final vehicle speed correction vehicle speed V c The variation in each operating cycle is limited to an upper limit value V by the protection processing unit 73H. UL and lower limit value V LL .

[0149] Therefore, even if the vehicle speed is fixed immediately before the steering wheel 11 restarts (the vehicle speed V is corrected and stored in the previous value storage unit 73B), c When the value of ) differs from the value of the vehicle speed V immediately after steering wheel 11 has resumed, the vehicle speed V is corrected. c The value also slowly changes to the value of the vehicle speed V detected by the vehicle speed sensor 501. That is, due to the suppression of the correction of vehicle speed V... c The rapid change in the value of θ also suppressed the target pinion angle θ. p * Or the rotation angle θ of rotating wheels 16 and 16 w and θ w Rapid changes.

[0150] In this embodiment, when steering wheel 11 resumes turning, a so-called correction of vehicle speed V is performed. c The variation in each operating cycle is limited to the upper limit value V. UL With lower limit value V LLThe time-varying values ​​between these values ​​are protected against changes, but offset processing can be used instead. For example, when steering wheel 11 resumes turning, the vehicle speed V will be corrected. c The difference between the current value and the previous value is set for the corrected vehicle speed V. c The offset value, and that offset value slowly changes to "0" over time.

[0151] Second Implementation Method

[0152] The steering control device according to the second embodiment will now be described. This embodiment basically employs the same... Figures 1 to 7 The configuration is the same as the first embodiment shown. The difference between this embodiment and the first embodiment lies in the method used to calculate the steering angle in the control device 50.

[0153] like Figure 9 As shown, the control device 50 includes a divider 101, an adder 102, and a differentiator 103. The divider 101 receives the steering torque T detected by the torque sensor 34. h The divider 101 uses the steering torque T h The torsional angle θ of the torsion bar is calculated by dividing by the torsional stiffness coefficient of the torsion bar, which is a component of the torque sensor 34. tb .

[0154] Adder 102 measures the torsion angle θ of the torsion bar calculated by divider 101. tb The steering angle θ calculated by the steering angle calculation unit 51 s Add them together to calculate the estimated steering angle θ es .

[0155] Differentiator 103 uses the estimated steering angle θ calculated by adder 102. es To calculate the estimated steering angular velocity ω by performing differentiation es For example, the target pinion angle calculation unit 62 uses the estimated steering angle θ es Instead of the steering angle θ calculated by the steering angle calculation unit 51 s And using the estimated steering angular velocity ω es Instead of using the steering angular velocity ω calculated by the differentiator 71, it performs the correction of vehicle speed V and calculates the target pinion angle θ. p * The processing.

[0156] Therefore, according to the second embodiment, in addition to the advantages of the first embodiment, the following advantages can also be obtained. As described above, when the vehicle is held at a constant steering angle θ by the steering wheel 11... sWhen the steering wheel 11 restarts in the current state, the fixed vehicle speed is released. At this point, as time passes, based on the steering state, the target pinion angle θ will be used to calculate... p * The final vehicle speed correction vehicle speed V c The value of θ changes slowly to the value of the vehicle speed V detected by the vehicle speed sensor 501. Here, in the first embodiment, the steering angle θ is used. s Steering angular velocity ω is used as a state variable to indicate the steering state, but in this implementation, a steering torque T is used instead. h Calculated estimated steering angle θ es And estimate the steering angular velocity ω es Therefore, when used to calculate the target pinion angle θ... p * The final vehicle speed correction vehicle speed V c When the value returns to the vehicle speed V detected by the vehicle speed sensor 501, responsiveness can be improved. The reason is as follows: Even though the steering wheel 11 makes a small amount of steering input, the steering input is immediately detected as the steering torque T of the steering wheel 11. h The change in the steering angle θ. s It is based on the rotation angle θ of the reaction motor 31 a The calculated point in time when the steering wheel 11 has been turned is related to the rotation angle θ of the reaction motor 31 that reflects the amount of steering wheel 11 turning. a And it is calculated as the steering angle θ s There is a slight time lag between the points in time. Therefore, the steering torque T h The steering responsiveness relative to steering wheel 11 is considered to be higher than that of steering angle θ. s The responsiveness of steering wheel 11.

[0157] Third Implementation Method

[0158] The steering control device according to the third embodiment will now be described. This embodiment differs from the first embodiment in that it calculates the target pinion angle θ. p * The method. This implementation can be applied to the second implementation mentioned above.

[0159] like Figure 10As shown, the target pinion angle calculation unit 62 includes a speed increase ratio calculation unit 111 and a multiplier 112. The speed increase ratio calculation unit 111 calculates the speed increase ratio ν based on the vehicle speed V detected by the vehicle speed sensor 501. The speed increase ratio calculation unit 111 uses a mapping M8 stored in the storage device of the control device 50 to calculate the speed increase ratio ν. The mapping M8 is a two-dimensional mapping that defines the relationship between the vehicle speed V and the speed increase ratio ν and has the following characteristic: as the value of the vehicle speed V increases, the value of the speed increase ratio ν decreases slowly.

[0160] Multiplier 112 uses the steering angle θ calculated by steering angle calculation unit 51 to... s The target pinion angle θ is calculated by multiplying the growth rate ν calculated by the growth rate calculation unit 111. p * Therefore, since the speed increase ratio increases as the vehicle speed V decreases, the rotation angle θ of wheels 16 and 16 increases when steering wheel 11 is operated. w and θ w The speed can change more rapidly. Since the speed-to-growth ratio decreases as the vehicle speed V increases, when the steering wheel 11 is operated, the rotation angle θ of the wheels 16 and 16 increases. w and θ w Change more slowly.

[0161] Here, when the speed increase ratio ν changes according to the vehicle speed V, there is a concern similar to that in the first embodiment. That is, for example, it is conceivable that the vehicle decelerates or accelerates while rotating. In this case, since the speed increase ratio ν changes with the vehicle speed V, the rotation angle θ of the rotating wheels 16 and 16... w and θ w It also changes according to the vehicle speed V. Therefore, similar to the first embodiment, there are concerns about changes in steering behavior not intended by the driver.

[0162] Therefore, in this embodiment, the following configuration is used as the target pinion angle calculation unit 62. For example... Figure 10 As shown, the target pinion angle calculation unit 62 includes a correction processing unit 120. The correction processing unit 120 corrects the speed increase ratio ν detected by the speed increase ratio calculation unit 111 according to the steering state of the steering wheel 11.

[0163] The correction processing unit 120 includes a differentiator 121, a hold direction determination unit 122, a determination unit 123, two previous value storage units 124 and 125, an upper limit value calculation unit 126, a lower limit value calculation unit 127, a determination unit 128, and a protection processing unit 129.

[0164] Differentiator 121 processes the steering angle θ calculated by steering angle calculation unit 51.s The steering angular velocity ω is calculated by differentiation. The steering determination unit 122 maintains the same characteristics as... Figure 5 The steering determination unit 122, as shown in the first embodiment, has the same function as the steering determination unit 72. The steering determination unit 122 is based on the vehicle speed V detected by the vehicle speed sensor 501 and the steering angle θ calculated by the steering angle calculation unit 51. s The steering angular velocity ω calculated by the differentiator 71 is used to determine whether the steering state of the steering wheel 11 is a holding steering state. When the steering state of the steering wheel 11 is determined to be a holding steering state, the holding steering determination unit 122 sets the value of the flag F0 to "1". When the steering state of the steering wheel 11 is determined not to be a holding steering state, the holding steering determination unit 122 sets the value of the flag F0 to "0".

[0165] Determining unit 123 has the same as Figure 6 The determination unit 123 performs the same function as the determination unit 73A according to the first embodiment. Here, the determination unit 123 receives the value of the flag F0 set by the steering hold determination unit 122, and sets the value of the flag F5, which indicates whether to limit the change in the rate of increase ν as the vehicle speed V changes, based on the received value of the flag F0. When the value of the flag F0 is "1", that is, when the steering wheel 11 is in the steering hold state, the determination unit 123 determines that the change in the rate of increase ν as the vehicle speed V changes is limited, and sets the value of the flag F5 to "1". When the value of the flag F0 is "0", that is, when the steering wheel 11 is not in the steering hold state, the determination unit 123 determines that the change in the rate of increase ν as the vehicle speed V changes is not limited, and sets the value of the flag F5 to "0".

[0166] The previous value storage unit 124 receives the value of the flag F6 set by the determination unit 128 and stores the received value of the flag F6. The value of the flag F6 stored in the previous value storage unit 124 is the previous value of the current value of the flag F6 set by the determination unit 128.

[0167] Previous value storage unit 125 receives the correction rate ratio ν calculated by the protection processing unit 129, which will be described later. c And the rate of increase of the correction received by the storage is higher than ν c The corrected growth rate ν stored in the previous value storage unit 125 c The corrected growth rate ν is calculated by the protection processing unit 129. c The previous value of the current value.

[0168] The upper limit calculation unit 126 has the same as Figure 6The upper limit calculation unit 73D shown in the first embodiment has the same function. Here, the upper limit calculation unit 126 receives the vehicle speed V detected by the vehicle speed sensor 501 and the steering angle θ calculated by the steering angle calculation unit 51. s And the steering angular velocity ω calculated by the differentiator 121, and based on the received vehicle speed V and steering angle θ s And the steering angular velocity ω is used to calculate the upper limit value ν of the change in the speed ratio ν for each operating cycle. UL .

[0169] The lower limit calculation unit 127 has the same characteristics as... Figure 6 The lower limit calculation unit 73E shown in the first embodiment has the same function. Here, the lower limit calculation unit 127 receives the vehicle speed V detected by the vehicle speed sensor 501 and the steering angle θ calculated by the steering angle calculation unit 51. s And the steering angular velocity ω calculated by the differentiator 121, and based on the received vehicle speed V and steering angle θ s And the steering angular velocity ω is used to calculate the lower limit ν of the change in the growth ratio ν for each operating cycle. LL .

[0170] Determining unit 128 has the same as Figure 6 The determination unit 73G shown in the first embodiment has the same function. Here, the determination unit 128 determines whether to restrict the change of the growth rate ratio ν in each operating cycle, and sets the value of the flag F6 indicating its determination result. The determination unit 128 receives the value of the flag F5 set by the determination unit 123 and the corrected growth rate ratio ν stored in the previous value storage unit 125. c Previous value ν cn-1 The growth rate ratio ν calculated by the growth rate calculation unit 111 and the previous value F6 of the flag F6 stored in the previous value storage unit 124. n-1 The determination unit 128 is based on the value of flag F5 and the corrected growth rate ratio ν. c Previous value ν cn-1 The growth rate ratio ν and the previous value of F6 as a marker of F6 n-1 To set the value of flag F6, follow these steps.

[0171] When the value of flag F5 is set to "0" and is maintained, that is, when the steering state of steering wheel 11 is not maintained at a constant steering angle θ s When the value of flag F6 changes from "0" to "1", that is, when the steering state of steering wheel 11 changes from not maintaining a constant steering angle θ, the determining unit 128 sets the value of flag F6 to "0". s The state changes so that it maintains a constant steering angle θs When the steering wheel 11 is in a certain state, the determining unit 128 sets the value of flag F6 to "1". When the value of flag F5 changes from "1" to "0", that is, when the steering state of the steering wheel 11 changes from maintaining a constant steering angle θ, the unit determines that the steering wheel 11 is in a certain state. s The state changes because it does not maintain a constant steering angle θ s When the state is reached, the determining unit 128 also sets the value of flag F6 to "1".

[0172] When the following expression (A6) is satisfied after the value of flag F5 has changed from "1" to "0", the determining unit 128 sets the value of flag F6 to "0". When the following expression (A6) is not satisfied, the determining unit 128 maintains the state where the value of flag F6 is set to "1".

[0173] |ν-ν c |≤ν th …(A6)

[0174] Here, "ν" is the growth rate calculated by the growth rate calculation unit 111, while "ν" is the growth rate calculated by the growth rate calculation unit 111. c "This is the corrected growth rate ratio calculated by the protection processing unit 129." th "This is the growth rate ratio threshold, and it is used to determine the growth rate ratio ν calculated by the growth rate ratio calculation unit 111 and the corrected growth rate ratio ν." c Is the difference between them small enough compared to the baseline value? (growth rate ratio ν) th It is set based on the following viewpoint: when the steering state of the steering wheel 11 changes from a holding steering state to a non-holding steering state, the correction speed-up ratio ν calculated by the protection processing unit 129 is used. c The difference between the actual growth rate ratio ν calculated by the growth rate ratio calculation unit 111 and the target pinion angle θ is suppressed. p * Rapid changes.

[0175] Protection processing unit 129 has the same as Figure 6 The protection processing unit 129 performs the same function as the protection processing unit 73H according to the first embodiment. Here, the protection processing unit 129 switches between active and inactive states for the limiting processing function on the growth rate ν calculated by the growth rate calculation unit 111, based on the value of the flag F6 set by the determination unit 128. When the value of the flag F6 is set to "1", the protection processing unit 129 enables the limiting processing function on the growth rate ν. The protection processing unit 129 uses the upper limit value ν calculated by the upper limit value calculation unit 126. UL and the lower limit value ν calculated by the lower limit calculation unit 127 LL This limits the change in the growth rate ratio ν for each operating cycle. The specific operation is as follows.

[0176] That is, when the change in the growth rate ratio ν over each operating cycle is greater than the upper limit value ν. UL At that time, the change in the growth rate ratio ν in each operating cycle is limited to the upper limit value ν. UL By limiting the variation to an upper limit value ν UL The changed growth rate ratio ν is calculated as the revised growth rate ratio ν. c When the change in the growth rate ratio ν over each operating cycle is less than the lower limit ν. LL At that time, the change in the growth rate ratio ν in each operating cycle is limited to the lower limit value ν. LL By limiting the variation to a lower bound value ν LL The changed growth rate ratio ν is calculated as the revised growth rate ratio ν. c In this way, the maximum and minimum changes in the growth rate ratio ν are determined by the upper limit value ν. UL and lower limit value ν LL Sure.

[0177] When the value of flag F6 is set to "0", the protection processing unit 129 disables the limiting processing function for the growth rate ratio ν. That is, the growth rate ratio ν calculated by the growth rate calculation unit 111 is calculated as the corrected growth rate ratio ν. c Without any changes required.

[0178] The operation of the third embodiment will now be described. When the vehicle is traveling straight forward with the steering wheel 11 in a neutral position, the determination unit 123 sets the value of flag F5 to "0". When the value of flag F5 changes from "0", the determination unit 128 sets the value of flag F6 to "0". Therefore, the limiting processing function for the growth ratio ν in the protection processing unit 129 is invalid. Therefore, the growth ratio ν calculated by the growth ratio calculation unit 111 is used as the corrected growth ratio ν. c That is, when the vehicle is traveling forward in a straight line, the target pinion angle θ is calculated using the growth ratio ν calculated by the growth ratio calculation unit 111. p * When the steering wheel 11 is held in the neutral position (steering angle θ) s When θ = 0°, the target pinion angle θ p * Set to the neutral position corresponding to the rotation axis 14 (rotation angle θ) w The value of "0°" is independent of the value of vehicle speed V and the value of acceleration ratio ν. Therefore, even when the vehicle speed V changes as the vehicle decelerates or accelerates, the driver will not feel discomfort.

[0179] When the vehicle turns while the steering wheel 11 is turned, the determining unit 123 sets the value of flag F5 to "0". When the value of flag F5 is "0", the determining unit 128 sets the value of flag F6 to "0". Therefore, the limiting processing function for the growth ratio ν in the protection processing unit 129 is invalid. Therefore, the growth ratio ν calculated by the growth ratio calculation unit 111 is calculated as the corrected growth ratio ν. c That is, since the growth rate ν calculated by the growth rate calculation unit 111 is used as the corrected growth rate ν. c To calculate the target pinion angle θ p * Therefore, the growth rate is ν or the target pinion angle θ p * The value changes with the vehicle speed V caused by deceleration or acceleration. When the steering wheel 11 is turned, the vehicle's travel path changes with the steering angle θ. s The steering wheel 11 changes from time to time. Therefore, even when the steering wheel 11 is turned and the steering angle ratio changes slightly with the change of vehicle speed V, the driver is unlikely to be aware of this and is unlikely to feel uncomfortable.

[0180] When the vehicle is held at a constant steering angle θ by steering wheel 11 s When rotating in the specified state, the determining unit 123 sets the value of flag F5 to "1". When the value of flag F5 changes from "0" to "1", the determining unit 128 sets the value of flag F6 to "1". Therefore, the limiting processing function for the speed ratio ν in the protection processing unit 129 is effective. Therefore, the change of the speed ratio ν in each operating cycle is limited to the upper limit value ν calculated by the upper limit value calculation unit 126. UL Or the lower limit value ν calculated by the lower limit calculation unit 127 LL For example, it is conceivable that the value of the growth ratio ν calculated by the growth ratio calculation unit 111 changes rapidly with the change in vehicle speed V due to vehicle deceleration or acceleration. In this case, the change in the growth ratio ν in each operating cycle becomes greater than the upper limit value ν. UL At that time, the change in the growth rate ratio ν in each operating cycle is limited to the upper limit value ν. UL Or lower limit value ν LL That is, as used to calculate the target pinion angle θ. p * The final growth rate ratio and the revised growth rate ratio ν c The change in each operating cycle does not exceed the upper limit value ν UL Therefore, the corrected growth rate ratio ν can be suppressed. c The value or target pinion angle θ p * The value changes rapidly with the change of vehicle speed V.

[0181] Therefore, as Figure 8 As shown in the left portion, when the vehicle begins to decelerate while the steering wheel 11 is held in the position of turning, it prevents the vehicle's actual driving trajectory L2 from changing in a way that would cause the vehicle to move inward relative to the driver's intended turning trajectory L1. That is, the vehicle can travel without significantly deviating from the driver's intended turning trajectory L1. Figure 8 As shown on the right side, when the vehicle begins to accelerate while the steering wheel 11 is in the controlled position, the actual driving trajectory L2 of the vehicle is prevented from changing to the point where the vehicle would veer outward from the driver's intended turning trajectory L1. That is, the vehicle can travel without significantly deviating from the driver's intended turning trajectory L1.

[0182] Then, when the vehicle turns while the steering wheel 11 is in the held-off state, and the steering of the steering wheel 11 restarts, the determination unit 123 sets the value of flag F5 to "0". When the value of flag F5 changes from "1" to "0", the determination unit 128 maintains the state where the value of flag F6 is set to "1". Therefore, the limiting processing function for the speed ratio ν in the protection processing unit 129 remains effective. Therefore, as used for calculating the target pinion angle θ p * The final growth rate ratio and the revised growth rate ratio ν c The variation in each operating cycle is limited to an upper limit value ν. UL Or lower limit value ν LL .

[0183] Here, it is conceivable that the rate of increase ν based on the vehicle speed V immediately before the steering wheel 11 restarts is different from the rate of increase ν based on the vehicle speed V immediately after the steering wheel 11 restarts. In this case, the target pinion angle θ based on the rate of increase ν immediately before the steering wheel 11 restarts is... p * And based on the target pinion angle θ of the speed increase ratio ν immediately after the steering wheel 11 restarts. p * They are also different. Therefore, the target pinion angle θ is calculated immediately using the increase ratio ν of the vehicle speed V based on the speed immediately following the restart of steering at the steering wheel 11. p * At that time, there exists an angle θ of the target pinion. p * Or the rotation angle θ of the rotating wheel 16 w Concerns about rapidly changing values.

[0184] In this respect, in this embodiment, when the steering wheel 11 resumes steering, the change in the growth ratio ν per operating cycle is limited to an upper limit value ν.UL Or lower limit value ν LL Therefore, the method used to calculate the target pinion angle θ can be suppressed. p * The final revised growth rate is higher than ν c The value changes rapidly. Corrected growth rate ratio ν c The values ​​depend on the vehicle's steering state (here, steering angular velocity ω and steering angle θ). s The speed (V) or driving state (in this case, vehicle speed V) changes slowly over time to the speed increase ratio ν calculated by the speed increase ratio calculation unit 111. Therefore, the target pinion angle θ can be suppressed. p * Or rotation angle θ w Rapid changes.

[0185] When the growth rate ν calculated by the growth rate calculation unit 111 is compared with the corrected growth rate ν limited by the protection processing unit 129... c The absolute value of the difference between them is equal to or less than the growth rate threshold ν th At this time, the determining unit 128 sets the value of flag F6 to "0". Therefore, the limiting processing function for the growth rate ratio ν in the protection processing unit 129 is invalid. Therefore, the growth rate ratio ν calculated by the growth rate ratio calculation unit 111 is used as the corrected growth rate ratio ν. c That is, used to calculate the target pinion angle θ p * The final growth rate ratio remains unchanged. That is, a more suitable target pinion angle θ corresponding to the growth rate ratio ν can be calculated based on the vehicle speed V. p * .

[0186] Therefore, according to the third embodiment, in addition to the advantages of the first embodiment, the following advantages can also be obtained: The steering angle θ calculated by the steering angle calculation unit 51 can be used. s And the target pinion angle θ is calculated based on the speed increase ratio ν calculated from the vehicle speed V. p * Depending on product specifications, it's conceivable that a steering angle θ must be limited based on vehicle speed V without using [the specified steering angle]. s Angle θ with the target pinion p * The target pinion angle θ is calculated using the mapping M1 between the relationships. p * And it can meet that requirement.

[0187] Fourth Implementation Method

[0188] The steering control device according to the fourth embodiment will now be described. This embodiment differs from the first embodiment in the configuration of the correction processing unit that corrects the vehicle speed V. This embodiment can be applied to the second or third embodiment described above.

[0189] like Figure 11 As shown, the correction processing unit 70A of the target pinion angle calculation unit 62 includes a rotation determination unit 131, a deceleration determination unit 132, and an acceleration determination unit 133, instead of maintaining the direction determination unit 72.

[0190] The rotation determination unit 131 receives the lateral acceleration G detected by the lateral acceleration sensor 502 installed in the vehicle. y and the steering angle θ calculated by the steering angle calculation unit 51 s And based on the received lateral acceleration G y and the received steering angle θ s To determine whether the vehicle is rotating. Lateral acceleration G y This refers to the lateral acceleration of the vehicle relative to its direction of travel when it rotates. The rotation determination unit 131 sets the value of flag F7 to indicate whether the vehicle is rotating. When it is determined that the vehicle is rotating, the rotation determination unit 131 sets the value of flag F7 to "1". When it is determined that the vehicle is not rotating, the rotation determination unit 131 sets the value of flag F7 to "0". Details of the rotation determination unit 131 will be described later.

[0191] The deceleration determination unit 132 receives the longitudinal acceleration G detected by the longitudinal acceleration sensor 503 installed in the vehicle. x The vehicle speed change ΔV per unit time calculated by the vehicle speed change calculation unit 504 installed in the control device 50, and the brake light signal S generated by the brake light switch 505 installed in the vehicle. stp Longitudinal acceleration G x It is the acceleration in the longitudinal direction relative to the vehicle's direction of travel. Brake light signal S stp This is an electrical signal indicating whether the brake lights located at the rear of the vehicle are on, thus indicating the driver's intention to decelerate. The deceleration determination unit 132 is based on the longitudinal acceleration G. x Vehicle speed change ΔV and brake light signal S stp Determine whether the vehicle is decelerating. The deceleration determination unit 132 sets the value of flag F8 to indicate whether the vehicle is decelerating. When it is determined that the vehicle is decelerating, the deceleration determination unit 132 sets the value of flag F8 to "1". When it is determined that the vehicle is not decelerating, the deceleration determination unit 132 sets the value of flag F8 to "0". Details of the deceleration determination unit 132 will be described later.

[0192] Acceleration determination unit 133 receives longitudinal acceleration G detected by longitudinal acceleration sensor 503 x The vehicle speed change ΔV per unit time calculated by the vehicle speed change calculation unit 504 and the acceleration operation amount θ detected by the accelerator position sensor 506 installed in the vehicle. ap The acceleration determination unit 133 is based on the longitudinal acceleration G. x Vehicle speed change ΔV and acceleration operation θ ap To determine whether the vehicle is accelerating. Acceleration maneuver θ ap This refers to the amount of accelerator pedal operation and indicates the driver's acceleration intention. The acceleration determination unit 133 sets the value of flag F9 to indicate whether the vehicle is accelerating. When it is determined that the vehicle is accelerating, the acceleration determination unit 133 sets the value of flag F9 to "1". When it is determined that the vehicle is not accelerating, the acceleration determination unit 133 sets the value of flag F9 to "0". Details of the acceleration determination unit 133 will be described later.

[0193] The vehicle speed calculation unit 73 receives the values ​​of flag F7 (as a result of rotation determination), flag F8 (as a result of deceleration determination), and flag F9 (as a result of acceleration determination). For example... Figure 6 The determination unit 73A of the vehicle speed calculation unit 73, as described in square brackets, sets an indicator for calculating the target pinion angle θ based on the values ​​of flag F7, flag F8, and flag F9. p * The value of vehicle speed V is determined by the value of the flag F3.

[0194] When the value of flag F7 is "0", that is, when the vehicle is not rotating, the determining unit 73A determines that the value of the vehicle speed V is not fixed, and sets the value of flag F3 to "0", regardless of the values ​​of flags F8 and F9. Therefore, the vehicle speed V detected by the vehicle speed sensor 501 is used as the value for calculating the target pinion angle θ. p * The final vehicle speed.

[0195] When both flag F7 and flag F8 are set to "1", i.e., when the vehicle decelerates while rotating, the determining unit 73A determines that the vehicle speed V is fixed and sets flag F3 to "1". Therefore, as used to calculate the target pinion angle θ... p * The final vehicle speed correction vehicle speed V c The value is fixed as the corrected vehicle speed V stored in the previous value storage unit 73B. c Previous value Vcn-1 .

[0196] When both flag F7 and flag F9 are set to "1", i.e., when the vehicle accelerates while rotating, the determining unit 73A determines that the vehicle speed V is fixed and sets flag F3 to "1". Therefore, as used to calculate the target pinion angle θ... p * The final vehicle speed correction vehicle speed V c The value is fixed as the corrected vehicle speed V stored in the previous value storage unit 73B. c Previous value V cn-1 .

[0197] The rotation determination unit 131 will be described in detail below. For example... Figure 12 As shown, the rotation determination unit 131 includes two absolute value calculation units 131A and 131B and three determination units 131C, 131D and 131E.

[0198] The absolute value calculation unit 131A calculates the lateral acceleration G calculated by the lateral acceleration sensor 502. y The absolute value. The absolute value calculation unit 131B calculates the steering angle θ calculated by the steering angle calculation unit 51. s The absolute value of.

[0199] The determining unit 131C receives the lateral acceleration G calculated by the absolute value calculation unit 131A. y The absolute value and the lateral acceleration threshold G stored in the storage device of the control device 50 yth Lateral acceleration threshold G yth It is set up based on the viewpoint used to determine whether the vehicle is rotating. The determination unit 131C will measure the lateral acceleration G. y The absolute value of the lateral acceleration threshold G yth The comparison is performed, and the value of flag F10 is set based on the comparison result. When the lateral acceleration G... y The absolute value is less than the lateral acceleration threshold G. yth At that time, the determining unit 131C sets the value of flag F10 to "0". When the lateral acceleration G y The absolute value is greater than the lateral acceleration threshold G. yth At that time, the determining unit 131C sets the value of flag F10 to "1".

[0200] The determining unit 131D receives the steering angle θ calculated by the absolute value calculation unit 131B. s The absolute value and the steering angle threshold θ stored in the storage device of the control device 50. sth2 Steering angle threshold θ sth2It is set up based on the viewpoint used to determine whether the vehicle is rotating. The determining unit 131D will determine the steering angle θ. s The absolute value and the steering angle threshold θ sth2 The comparison is performed, and the value of flag F11 is set based on the comparison result. When the steering angle θ... s The absolute value is less than the steering angle threshold θ sth2 When the steering angle θ is... s The absolute value is greater than the steering angle threshold θ sth2 At that time, the determining unit 131D sets the value of flag F11 to "1".

[0201] The determining unit 131E receives the value of flag F10 set by the determining unit 131C and the value of flag F11 set by the determining unit 131D. The determining unit 131E sets the value of flag F7 based on the values ​​of flags F10 and F11 as a determination result indicating whether the vehicle is rotating. When the value of at least one of flags F10 and F11 is "0", the determining unit 131E determines that the vehicle is not rotating and sets the value of flag F7 to "0". When the values ​​of both flags F10 and F11 are "1", the determining unit 131E determines that the vehicle is rotating and sets the value of flag F7 to "1".

[0202] Lateral acceleration threshold G yth and steering angle threshold θ sth2 The deceleration determination unit 132 can be changed according to the vehicle speed V. The deceleration determination unit 132 will be described in detail below.

[0203] like Figure 13 As shown, the deceleration determination unit 132 includes four determination units 132A, 132B, 132C, and 132D. Determination unit 132A receives the longitudinal acceleration G detected by the longitudinal acceleration sensor 503. x And the longitudinal acceleration threshold G stored in the storage device of the control device 50 yth1 Longitudinal acceleration threshold G yth1 It is designed based on the viewpoint of determining whether the vehicle is decelerating. The determination unit 132A measures the longitudinal acceleration G. x With longitudinal acceleration threshold G yth1 The comparison is performed, and the value of flag F12 is set based on the comparison result. When the longitudinal acceleration G... x The value is less than the longitudinal acceleration threshold G yth1 At that time, the determining unit 132A sets the value of flag F12 to "0". When the longitudinal acceleration G x The value is greater than the longitudinal acceleration threshold G yth1 At that time, the determining unit 132A sets the value of flag F12 to "1".

[0204] The determining unit 132B receives the vehicle speed change ΔV per unit time calculated by the vehicle speed change calculation unit 504 and the vehicle speed change threshold ΔV stored in the storage device of the control device 50. th1 Vehicle speed change threshold ΔV th1 It is designed based on the viewpoint of determining whether the vehicle is decelerating. The determining unit 132B compares the vehicle speed change ΔV per unit time with the vehicle speed change threshold ΔV. th1 A comparison is made, and the value of flag F13 is set based on the comparison result. When the vehicle speed change ΔV per unit time is less than the vehicle speed change threshold ΔV... th1 When the value of the vehicle speed change ΔV per unit time is greater than the vehicle speed change threshold ΔV, the unit 132B sets the value of the flag F13 to "0". th1 At that time, the determining unit 132B sets the value of flag F13 to "1".

[0205] The determination unit 132C receives the brake light signal S generated by the brake light switch 505. stp When the brake light signal S stp When the brake lights are off, the determining unit 132C sets the value of flag F14 to "0". When the brake light signal S... stp When the brake light is on, the determination unit 132C sets the value of flag F14 to "1".

[0206] The determining unit 132D receives the value of flag F12 set by the determining unit 132A, the value of flag F13 set by the determining unit 132B, and the value of flag F14 set by the determining unit 132C. The determining unit 132D sets the value of flag F8 based on the values ​​of flags F12, F13, and F14 as a determination result indicating whether the vehicle is decelerating. When the value of at least one of flags F12, F13, and F14 is "0", the determining unit 132D determines that the vehicle is not decelerating and sets the value of flag F8 to "0". When the values ​​of all flags F12, F13, and F14 are "1", the determining unit 132D determines that the vehicle is decelerating and sets the value of flag F8 to "1".

[0207] Longitudinal acceleration threshold G yth1 and vehicle speed change threshold ΔV th1The speed can be changed according to the vehicle speed V. The deceleration determination unit 132 can be configured without the determination unit 132C. In this case, when at least one of the flags F12 and F13 has a value of "0", the determination unit 132D sets the value of flag F8 to "0". When both flags F12 and F13 have a value of "1", the determination unit 132D sets the value of flag F8 to "1".

[0208] The acceleration determination unit 133 will be described in detail below. Figure 14 As shown, the acceleration determination unit 133 includes four determination units 133A, 133B, 133C and 133D.

[0209] The determining unit 133A receives the longitudinal acceleration G detected by the longitudinal acceleration sensor 503. x And the longitudinal acceleration threshold G stored in the storage device of the control device 50 yth2 Longitudinal acceleration threshold G yth2 It is based on the viewpoint used to determine whether the vehicle is accelerating. The determination unit 133A measures the longitudinal acceleration G. x With longitudinal acceleration threshold G yth2 The comparison is performed, and the value of flag F15 is set based on the comparison result. When the longitudinal acceleration G... x The value is less than the longitudinal acceleration threshold G yth2 At that time, the determining unit 133A sets the value of flag F15 to "0". When the longitudinal acceleration G x The value is greater than the longitudinal acceleration threshold G yth2 At that time, the determining unit 133A sets the value of flag F15 to "1".

[0210] The determining unit 133B receives the vehicle speed change ΔV per unit time calculated by the vehicle speed change calculation unit 504 and the vehicle speed change threshold ΔV stored in the storage device of the control device 50. th2 Vehicle speed change threshold ΔV th2 It is designed based on the viewpoint of determining whether the vehicle is accelerating. The determining unit 133B compares the vehicle speed change ΔV per unit time with the vehicle speed change threshold ΔV. th2 A comparison is made, and the value of flag F16 is set based on the comparison result. When the vehicle speed change ΔV per unit time is less than the vehicle speed change threshold ΔV... th2 When the value of the vehicle speed change ΔV per unit time is greater than the vehicle speed change threshold ΔV, the unit 133B sets the value of flag F16 to "0". th2 At that time, the determination unit 133B sets the value of flag F16 to "1".

[0211] The determining unit 133C receives the acceleration operation amount θ detected by the accelerometer position sensor 506. ap And the acceleration operation threshold θ stored in the storage device of the control device 50 apth Acceleration operation threshold θ apth It is set up based on the viewpoint of determining whether the vehicle is accelerating. The determining unit 133C will determine the acceleration operation amount θ. ap With acceleration operation threshold θ apth The comparison is performed, and the value of flag F17 is set based on the comparison result. When the acceleration operation amount θ... ap The value is less than the acceleration operation threshold θ apth At that time, the determination unit 133C sets the value of flag F17 to "0". When the acceleration operation amount θ ap The value is greater than the acceleration operation threshold θ apth At that time, the determination unit 133C sets the value of flag F17 to "1".

[0212] The determining unit 133D receives the value of flag F15 set by the determining unit 133A, the value of flag F16 set by the determining unit 133B, and the value of flag F17 set by the determining unit 133C. The determining unit 133D sets the value of flag F9 based on the values ​​of flags F15, F16, and F17 as a determination result indicating whether the vehicle is accelerating. When at least one of flags F15, F16, and F17 has a value of "0", the determining unit 133D determines that the vehicle is not accelerating and sets the value of flag F9 to "0". When all the values ​​of flags F15, F16, and F17 are "1", the determining unit 133D determines that the vehicle is accelerating and sets the value of flag F9 to "1".

[0213] Longitudinal acceleration threshold G yth2 and vehicle speed change threshold ΔV th2 The acceleration determination unit 133 can be adjusted according to the vehicle speed V. The determination unit 133 can be configured without the determination unit 133C. In this case, when at least one of the flags F15 and F16 has a value of "0", the determination unit 133D sets the value of flag F9 to "0". When both flags F15 and F16 have a value of "1", the determination unit 133D sets the value of flag F9 to "1".

[0214] Therefore, according to the fourth embodiment, in addition to the advantages of the first embodiment, the following advantages can also be obtained: regardless of whether the steering wheel 11 is maintained at a constant steering angle θ s When the vehicle decelerates or accelerates while rotating, this will be used to calculate the target pinion angle θ. p *The final vehicle speed correction vehicle speed V c The fixed speed is the vehicle speed immediately before it is determined that the vehicle is decelerating while rotating or immediately before it is determined that the vehicle is accelerating while rotating. Therefore, as... Figure 8 As shown in the left part, when the vehicle decelerates while turning, regardless of whether the steering wheel 11 remains at a constant steering angle θ s This prevents the vehicle's actual driving trajectory L2 from changing into an inward movement relative to the driver's intended rotational trajectory L1. For example... Figure 8 As shown in the right part, when the vehicle accelerates while turning, regardless of whether the steering wheel 11 remains at a constant steering angle θ s This prevents the vehicle's actual driving trajectory L2 from changing to a point where the vehicle protrudes outward from the driver's intended turning trajectory L1. Therefore, regardless of whether the steering wheel 11 remains at a constant steering angle θ... s When a vehicle decelerates or accelerates while rotating, it can suppress changes in vehicle behavior not intended by the driver.

[0215] Without determining whether steering wheel 11 maintains a constant steering angle θ s In the case where the steering wheel 11 is kept at a constant steering angle θ s At that time, it is used to calculate the target pinion angle θ. p * The vehicle speed is also constant. Therefore, even when the vehicle is held at a constant steering angle θ by steering wheel 11... s When decelerating or accelerating in a certain state, it can also suppress changes in vehicle behavior not intended by the driver.

[0216] When the vehicle is turned by steering wheel 11, the vehicle's trajectory changes with the steering angle θ. s The steering angle ratio changes from time to time. Therefore, even when the steering angle ratio changes slightly with the vehicle speed V, the driver is unlikely to be aware of it and is unlikely to feel uncomfortable. Depending on the product specifications, given the improved steering capability, it is conceivable that the steering angle ratio should not change when the vehicle is decelerating or accelerating while turning, regardless of whether the steering wheel 11 is held or not, and this requirement can be met.

[0217] When using the vehicle's deceleration, in addition to being based on the longitudinal acceleration G... x In addition to the vehicle speed change ΔV per unit time, it is also based on the brake light signal S. stp When the determined configuration is used as the deceleration determining unit 132, the vehicle's deceleration can be determined more appropriately. For example, when the vehicle is traveling uphill, it can be assumed that the vehicle speed V will decrease even if the driver does not intend to slow down. In this regard, the brake light signal S can be taken into account. stpBased on the driver's intentions, the vehicle's deceleration on an uphill road can be determined more appropriately.

[0218] When using the vehicle's acceleration, in addition to the longitudinal acceleration G, x In addition to the vehicle speed change ΔV per unit time, it is also based on the acceleration operation amount θ ap When the determined configuration is used as the acceleration determination unit 133, the vehicle's acceleration can be determined more appropriately. For example, when the vehicle is traveling downhill, it can be considered that the vehicle's speed V will increase even if the driver does not intend to accelerate. In this regard, the acceleration operation amount θ can be taken into account. ap The acceleration of the vehicle on a downhill road can be determined more appropriately based on the driver's intention.

[0219] Fifth Implementation Method

[0220] The steering control device according to the fifth embodiment will now be described. This embodiment differs from the fourth embodiment in the configuration of the rotation determination unit.

[0221] like Figure 15 As shown, the rotation determination unit 131 includes a slip angle calculation unit 141A and a determination unit 141B. The slip angle calculation unit 141A receives the steering angle θ calculated by the steering angle calculation unit 51. s And the vehicle speed V detected by vehicle speed sensor 501, and based on the steering angle θ s And the vehicle speed V is used to calculate the slip angle θ sa Slip angle θ sa The slip angle is the angle formed by the direction of the rotating wheel 16 and the direction of travel of the vehicle. The slip angle calculation unit 141A uses the mapping M9 stored in the storage device of the control device 50 to calculate the slip angle θ. sa Mapping M9 is where the steering angle θ is defined based on the vehicle speed V. s With the slip angle θ sa A three-dimensional mapping of the relationship between them, and possessing the following properties. That is, with the turning angle θ s As the absolute value of θ increases and the vehicle speed V increases, the slip angle θ sa The absolute value increases.

[0222] The determining unit 141B receives the slip angle θ calculated by the slip angle calculation unit 141A. sa The absolute value and the slip angle threshold θ stored in the storage device of the control device 50 sath Slip angle threshold θ sath It is set up based on the viewpoint used to determine whether the vehicle is rotating. The determining unit 141B will determine the slip angle θ. sa The absolute value and the slip angle threshold θsath The comparison is performed, and the value of flag F7 is set based on the comparison result. When the slip angle θ... sa The absolute value is less than the slip angle threshold θ sath When the vehicle is not rotating, the determining unit 141B determines that the vehicle is not rotating and sets the value of the flag F7 to "0". When the slip angle θ... sa The absolute value is greater than the slip angle threshold θ sath At that time, the determining unit 141B determines that the vehicle is rotating and sets the value of the flag F7 to "1".

[0223] Therefore, according to the fifth embodiment, the following advantages can be obtained. It is possible to base the steering angle θ s The vehicle speed V is used to determine whether the vehicle is rotating.

[0224] Sixth Implementation Method

[0225] The steering control device according to the sixth embodiment will now be described. This embodiment differs from the fourth embodiment in the arrangement of the rotation determination unit, the deceleration determination unit, and the acceleration determination unit.

[0226] The vehicle's wheels are rotatably supported on the vehicle body via hub unit bearings, and tire force sensors that detect tire force can be installed in each hub unit bearing. Tire force is the load acting between the road surface and each wheel.

[0227] like Figure 19 As shown, the load acting between the road surface and each wheel can be represented by a total of six forces. These six forces include three forces acting in the X, Y, and Z axes, and three moments acting around the X, Y, and Z axes. Here, the X-axis is the longitudinal horizontal direction of the wheel. The Y-axis is the lateral horizontal direction of the wheel. The Z-axis is the vertical direction of the wheel. The force acting on each wheel in the X-axis direction is called the longitudinal load (longitudinal force) F. x The force acting on each wheel in the Y-axis direction is called the lateral load (lateral force) F. y The force acting on each wheel in the Z-axis direction is called the vertical load (vertical force) F. z The torque acting around the X-axis of each wheel is called the roll moment M. x The torque acting around the Y-axis of each wheel is called the pitching torque M. y The torque acting around the Z-axis of each wheel is called the yaw moment M. z .

[0228] When such a tire force sensor is provided, the following configuration can be used as the rotation determination unit 131, deceleration determination unit 132, and acceleration determination unit 133. For example... Figure 16As shown, the rotation determination unit 131 includes three absolute value calculation units 151A, 151B and 151C and four determination units 151D, 151E, 151F and 151G.

[0229] The absolute value calculation unit 151A calculates the lateral load F detected by the tire force sensor. y The absolute value. The absolute value calculation unit 151B calculates the yaw moment M detected by the tire force sensor. z The absolute value of.

[0230] The absolute value calculation unit 151C calculates the roll moment M detected by the tire force sensor. x The absolute value of the load. The determining unit 151D receives the lateral load F calculated by the absolute value calculation unit 151A. y The absolute value and the lateral load threshold F stored in the storage device of the control device 50 yth Lateral load threshold F yth It is set up based on the viewpoint used to determine whether the vehicle is rotating. The determining unit 151D will apply the lateral load F... y The absolute value of the lateral load threshold F yth The comparison is performed, and the value of flag F18 is set based on the comparison result. When the lateral load F... y The absolute value is less than the lateral load threshold F yth When the lateral load F is applied, the determining unit 151D sets the value of flag F18 to "0". y The absolute value is greater than the lateral load threshold F yth At that time, the determining unit 151D sets the value of flag F18 to "1".

[0231] The determining unit 151E receives the yaw moment M calculated by the absolute value calculation unit 151B. z The absolute value and the yaw moment threshold M stored in the storage device of the control device 50 zth Yaw moment threshold M zth It is designed based on the viewpoint used to determine whether the vehicle is rotating. The determining unit 151E will determine the yaw moment M. z The absolute value of the yaw moment threshold M zth The comparison is performed, and the value of flag F19 is set based on the comparison result. When the yaw moment M... z The absolute value is less than the yaw moment threshold M zth At that time, the determining unit 151E sets the value of flag F19 to "0". When the yaw moment M z The absolute value is greater than the yaw moment threshold M zth At that time, the determining unit 151E sets the value of flag F19 to "1".

[0232] The determining unit 151F receives the roll moment M calculated by the absolute value calculation unit 151C. x The absolute value and the tilt moment threshold M stored in the storage device of the control device 50 xth Roll moment threshold M xth It is designed based on the viewpoint used to determine whether the vehicle is rotating. The determining unit 151F will determine the roll moment M. x The absolute value of the roll moment threshold M xth The comparison is performed, and the value of flag F20 is set based on the comparison result. When the roll moment M x The absolute value is less than the roll moment threshold M xth At that time, it is determined that unit 151F will set the value of flag F20 to "0". When the roll moment M x The absolute value is greater than the roll moment threshold M xth At that time, the determining unit 151F sets the value of flag F20 to "1".

[0233] The determining unit 151G receives the value of flag F18 set by the determining unit 151D, the value of flag F19 set by the determining unit 151E, and the value of flag F20 set by the determining unit 151F. Based on the values ​​of flags F18, F19, and F20, the determining unit 151G sets the value of flag F7 to indicate whether the vehicle is rotating. When at least one of flags F18, F19, and F20 has a value of "0", the determining unit 151G determines that the vehicle is not rotating and sets the value of flag F7 to "0". When all flags F18, F19, and F20 have values ​​of "1", the determining unit 151G determines that the vehicle is rotating and sets the value of flag F7 to "1".

[0234] like Figure 17 As shown, the deceleration determination unit 132 includes four determination units 161A, 161B, 161C, and 161D. Determination unit 161A receives the longitudinal load F calculated by the tire force sensor. x And the longitudinal load threshold F stored in the storage device of the control device 50 xth1 Longitudinal load threshold F xth1 It is designed based on the viewpoint of determining whether the vehicle is decelerating. The determination unit 161A will determine the longitudinal load F. x With longitudinal load threshold F xth1 The comparison is performed, and the value of flag F21 is set based on the comparison result. When the longitudinal load F x The value is less than the longitudinal load threshold F xth1 When the longitudinal load F is applied, the determining unit 161A sets the value of flag F21 to "0". x The value is greater than the longitudinal load threshold Fxth1 At that time, the determining unit 161A sets the value of flag F21 to "1".

[0235] The determining unit 161B receives the vertical load F detected by the tire force sensor. z and the vertical load threshold F stored in the storage device of the control device 50 zth1 Vertical load threshold F zth1 It is designed based on the viewpoint of determining whether the vehicle is decelerating. The determining unit 161B will apply the vertical load F... z With vertical load threshold F zth1 The comparison is performed, and the value of flag F22 is set based on the comparison result. When the vertical load F... z The value is less than the vertical load threshold F zth1 When the vertical load F is applied, the determining unit 161B sets the value of flag F22 to "0". z The value is greater than the vertical load threshold F zth1 At that time, the determining unit 161B sets the value of flag F22 to "1".

[0236] The determining unit 161C receives the pitch moment M detected by the tire force sensor. y And the pitch moment threshold M stored in the storage device of the control device 50 yth1 Pitch moment threshold M yth1 It is designed based on the viewpoint of determining whether the vehicle is decelerating. The determination unit 161C will determine the pitch moment M. y With pitch moment threshold M yth1 The comparison is performed, and the value of flag F23 is set based on the comparison result. When the pitch moment M... y The value is less than the pitch moment threshold M yth1 At that time, the determination unit 161C sets the value of flag F23 to "0". When the pitch moment M y The value is greater than the pitch moment threshold M yth1 At that time, the determining unit 161C sets the value of flag F23 to "1".

[0237] The determining unit 161D receives the value of flag F21 set by the determining unit 161A, the value of flag F22 set by the determining unit 161B, and the value of flag F23 set by the determining unit 161C. Based on the values ​​of flags F21, F22, and F23, the determining unit 161D sets the value of flag F8 to indicate whether the vehicle is decelerating. When at least one of flags F21, F22, and F23 is "0", the determining unit 161D determines that the vehicle is not decelerating and sets the value of flag F8 to "0". When all flags F21, F22, and F23 are "1", the determining unit 161D determines that the vehicle is decelerating and sets the value of flag F8 to "1".

[0238] like Figure 18 As shown, the acceleration determination unit 133 includes four determination units 171A, 171B, 171C, and 171D. Determination unit 171A receives the longitudinal load F detected by the tire force sensor. x And the longitudinal load threshold F stored in the storage device of the control device 50 xth2 Longitudinal load threshold F xth2 It is set up based on the viewpoint used to determine whether the vehicle is accelerating. The determination unit 171A will apply the longitudinal load F... x With longitudinal load threshold F xth2 The comparison is performed, and the value of flag F24 is set based on the comparison result. When the longitudinal load F x The value is less than the longitudinal load threshold F xth2 When the longitudinal load F is applied, the determining unit 171A sets the value of flag F24 to "0". x The value is greater than the longitudinal load threshold F xth2 At that time, the determining unit 171A sets the value of flag F24 to "1".

[0239] The determining unit 171B receives the vertical load F detected by the tire force sensor. z and the vertical load threshold F stored in the storage device of the control device 50 zth2 Vertical load threshold F zth2 It is set up based on the viewpoint used to determine whether the vehicle is accelerating. The determination unit 171B will apply the vertical load F. z With vertical load threshold F zth2 The comparison is performed, and the value of flag F25 is set based on the comparison result. When the vertical load F... z The value is less than the vertical load threshold F zth2 When the vertical load F is applied, the determining unit 171B sets the value of flag F25 to "0". z The value is greater than the vertical load threshold F zth2At that time, the determining unit 171B sets the value of flag F25 to "1".

[0240] The determining unit 171C receives the pitch moment M detected by the tire force sensor. y And the pitch moment threshold M stored in the storage device of the control device 50 yth2 Pitch moment threshold M yth2 It is based on the viewpoint used to determine whether the vehicle is accelerating. The determination unit 171C will determine the pitch moment M. y With pitch moment threshold M yth2 The comparison is performed, and the value of flag F26 is set based on the comparison result. When the pitch moment M... y The value is less than the pitch moment threshold M yth2 At that time, the determination unit 171C sets the value of flag F26 to "0". When the pitch moment M y The value is greater than the pitch moment threshold M yth2 At that time, the determining unit 171C sets the value of flag F26 to "1".

[0241] The determining unit 171D receives the value of flag F24 set by the determining unit 171A, the value of flag F25 set by the determining unit 171B, and the value of flag F26 set by the determining unit 171C. Based on the values ​​of flags F24, F25, and F26, the determining unit 171D sets the value of flag F9 to indicate whether the vehicle is accelerating. When at least one of flags F24, F25, and F26 is "0", the determining unit 171D determines that the vehicle is not accelerating and sets the value of flag F9 to "0". When all the values ​​of flags F24, F25, and F26 are "1", the determining unit 171D determines that the vehicle is accelerating and sets the value of flag F9 to "1".

[0242] Therefore, according to the sixth embodiment, the following advantages can be obtained. When a tire force sensor is provided in each wheel of the vehicle, it is possible to determine whether the vehicle is rotating, decelerating, or accelerating based on the tire force detected by the tire force sensor.

[0243] Seventh Implementation Method

[0244] The steering control device according to the seventh embodiment will now be described. This embodiment differs from the fourth embodiment in the configuration of the target pinion angle calculation unit 62.

[0245] like Figure 20 As shown, the target pinion angle calculation unit 62 includes an angle calculation unit 180A and a correction processing unit 180B. The angle calculation unit 180A has the same... Figure 4The angle calculation unit 180A has the same function as the angle calculation unit 70B shown in the first embodiment. The angle calculation unit 180A receives the steering angle θ calculated by the steering angle calculation unit 51. s and the vehicle speed V detected by vehicle speed sensor 501, and based on the received steering angle θ s And the received vehicle speed V, using the previously mentioned mapping M1 to calculate the target pinion angle θ. p * .

[0246] The correction processing unit 180B includes a differentiator 181, a gain calculation unit 182, and a protection processing unit 183. The differentiator 181 processes the steering angle θ calculated by the steering angle calculation unit 51. s The steering angular velocity ω is calculated by performing differentiation.

[0247] The gain calculation unit 182 calculates the gain G based on the steering angular velocity ω calculated by the differentiator 181. c The gain calculation unit 182 uses the mapping M10 stored in the storage device of the control device 50 to calculate the gain G. c Mapping M10 limits the steering angular velocity ω and the gain G. c A two-dimensional mapping of the relationship between them, and with the following properties: That is, when the absolute value of the steering angular velocity ω is equal to or less than the threshold ω... th2 At that time, the gain G c The value remains at "0". When the absolute value of the steering angular velocity ω is greater than the threshold ω th2 At that time, the gain G c The value of increases rapidly with the increase of the absolute value of the steering angular velocity ω and reaches "1". In the gain G c Once the value of G has reached "1", it is independent of the increase in the absolute value of the steering angular velocity ω. c The value remains "1". Threshold ω th2 It is set based on the steering angular velocity ω when the steering wheel 11 is in a steering state or when the steering wheel 11 is turning slowly.

[0248] Protection processing unit 183 receives the target pinion angle θ calculated by angle calculation unit 180A. p * and the gain G calculated by the gain calculation unit 182 c The protection processing unit 183 will adjust the target pinion angle θ. p * The variation in each operating cycle is limited to a limit value Δθ. The limit value Δθ is based on the target pinion angle θ used to suppress this variation. p *The viewpoint is set to change rapidly. The limiting value Δθ can be a fixed value, or it can depend on the steering angular velocity ω and the steering angle θ. s Or a variable that changes due to vehicle speed V. The protection processing unit 183 multiplies the limit value Δθ by the gain G. c To calculate the final limit value Δθ.

[0249] When the gain G c When the value of is "0", the final limit value Δθ is "0", and therefore the target pinion angle θ p * The change in each operating cycle is limited to "0". Therefore, when the value of the steering angular velocity ω is equal to or less than the threshold ω th2 At that time, the target pinion angle θ p * It is fixed when the value of the steering angular velocity ω has reached or is less than the threshold ω. th2 The value when the gain G is [value]. c When the value is "1", the target pinion angle θ p * The variation in each operating cycle is limited to the limit value Δθ.

[0250] The operation of the seventh embodiment will now be described. For example, when the vehicle is held at a constant steering angle θ by the steering wheel 11. s When rotating in this state, the value of the steering angular velocity ω is "0". At this time, due to the gain G c The value is "0", therefore the target pinion angle θ p * The change in each operating cycle is limited to "0". Therefore, when the steering wheel 11 is in a steering state (more precisely, when the steering angular velocity ω has reached or fallen below the threshold ω), the change is limited to "0". th2 When the value is θ, regardless of the change in vehicle speed V, the final target pinion angle θ used to control the rotating motor 41 is the corrected target pinion angle. pc * Fixed to be based on steering angle θ s The target pinion angle θ of the vehicle speed V p * The same value. That is, the corrected target pinion angle θ. pc * Or the value of the steering angle ratio does not change with the vehicle speed V.

[0251] Therefore, as Figure 8 As shown in the left part, when the vehicle is held at a constant steering angle θ by steering wheel 11. sWhen decelerating while rotating in a certain state, it prevents the vehicle's actual driving trajectory L2 from changing, thus causing the vehicle to move inward relative to the driver's intended rotation trajectory L1. For example... Figure 8 As shown on the right side, when the vehicle is held at a constant steering angle θ by steering wheel 11. s When accelerating while rotating in a certain state, it prevents the vehicle's actual driving trajectory L2 from changing to a point where the vehicle would veer outward from the driver's intended rotation trajectory L1. Because it can suppress changes in vehicle behavior not intended by the driver, the driver is less likely to experience discomfort.

[0252] When steering wheel 11 is slowly turned at a steering angular velocity ω equal to or below the threshold, the target pinion angle θ p * The value of the steering angle ratio is fixed in the same way as when the steering wheel 11 is held.

[0253] When the vehicle is held at a constant steering angle θ by steering wheel 11 s When the steering wheel 11 restarts steering while in a certain state, there is a concern regarding the following: Specifically, the target pinion angle θ, which is fixed immediately before the steering wheel 11 restarts steering, is potentially affected. pc * The value and the target pinion angle θ calculated by the angle calculation unit 180A immediately after the steering wheel 11 restarts. p * The values ​​will be different from each other.

[0254] In this respect, when the steering angular velocity ω becomes greater than the threshold ω due to the restart of steering wheel 11. th2 At that time, the gain G c The value is set to, for example, "1". Therefore, even when the target pinion angle θ is calculated by the angle calculation unit 180A immediately after the steering wheel 11 resumes turning, the value is still set to "1". p * The value becomes different from the fixed correction target pinion angle θ immediately before the steering of the steering wheel 11 restarts. pc * The value of the target pinion angle θ p * The variation in each operating cycle is also limited to a limit value Δθ by the protection processing unit 183. Therefore, the corrected target pinion angle θ, which is the final target pinion angle used to control the rotary motor 41, is... pc * The angle slowly changes over time to the target pinion angle θ calculated by the angle calculation unit 180A. p * That is, because the correction of the target pinion angle θ was suppressed. pc* The rapid change in the value of can therefore suppress rapid changes in the steering angle ratio.

[0255] Therefore, according to the seventh embodiment, in addition to the advantages of the first embodiment, the following advantages can also be obtained: The target pinion angle θ can be corrected using an electrical signal (here, the steering angular velocity ω) without performing deterministic processes such as determining the holding of the steering wheel 11 and the rotation or acceleration / deceleration of the vehicle. p * Or the steering angle ratio, this electrical signal is used to determine the state variables of the process. Since it is not necessary to determine processes such as holding the steering wheel 11 and turning or accelerating / decelerating the vehicle, the computational load on the control unit 50 can also be suppressed.

[0256] Alternatively, it can be used with Figure 6 The same configuration as the corrected vehicle speed calculation unit 73 shown in the first embodiment is used as the correction processing unit 180B. In this case, a correction processing unit 180B is provided. Figure 20 The gain calculation unit 182 shown is not the determination unit 73A. Switch 73C receives the gain G. c Instead of the F3 symbol, the vehicle speed V is determined by the target pinion angle θ. p * Replace and correct vehicle speed V c The angle θ of the target pinion is corrected. pc * Replacement. The upper limit calculation unit 73D calculates the angle θ of the target pinion. p * The upper limit of the change for each operating cycle, rather than for the temporary vehicle speed value V. temp The upper limit of the change V in each operating cycle UL The lower limit calculation unit 73E calculates the angle θ of the target pinion. p * The lower limit of the change for each operating cycle, rather than for the temporary vehicle speed value V. temp The lower limit of the change in each operating cycle, V LL Unit 73G determines whether to restrict the target pinion angle θ. p * The value of flag F4, which indicates the determination of the result, is set for each operating cycle. The protection processing unit 73H will set the target pinion angle θ. p * Instead of the temporary vehicle speed value V temp The variation in each operating cycle is limited to an upper or lower limit. In this case, the same advantages as the first and seventh embodiments can also be obtained.

[0257] It can be adopted with Figure 10 The same configuration as the correction processing unit 120 shown in the third embodiment is used as the correction processing unit 180B. In this case, a correction processing unit 180B is provided. Figure 20 The gain calculation unit 182 shown is used instead of the steering determination units 122 and 123. The speed ratio ν is determined by the target pinion angle θ. p * Replacement, while correcting the growth rate ratio ν c The angle θ of the target pinion is corrected. pc * Replacement. Upper limit calculation unit 126 calculates the target pinion angle θ. p * The upper limit of the change per operating cycle, rather than the upper limit of the change per operating cycle for the growth rate ratio ν. UL The lower limit calculation unit 73E calculates the angle θ of the target pinion. p * The lower bound of the change in each operating cycle, rather than the lower bound of the change in the growth rate ν in each operating cycle. LL The protection processing unit 129 will adjust the target pinion angle θ. p * Instead of limiting the change in the growth rate ratio ν to an upper or lower limit for each operating cycle, the same advantages as in the first and seventh embodiments can be obtained in this case.

[0258] Eighth Implementation Method

[0259] The steering control device according to the eighth embodiment will now be described. This embodiment essentially has the same characteristics as... Figures 1 to 7 The configuration is the same as the first embodiment shown.

[0260] Depending on the product specifications, it may be necessary to use steering reaction force to transmit the vehicle's status to the driver. For example, the vehicle status that needs to be transmitted to the driver is the status of the turning wheels 16 and 16 contacting obstacles such as curbs when the vehicle starts from a stationary position.

[0261] Therefore, in this embodiment, in order to transmit the vehicle's status to the driver using steering reaction force, the steering reaction force command value calculation unit 52 of the reaction control unit 50a is configured as follows. For example... Figure 21 As shown, the steering reaction force command value calculation unit 52 includes a target steering reaction force calculation unit 191, an axial force calculation unit 192, and a subtractor 193.

[0262] Target steering reaction force calculation unit 191 is based on steering torque T h The target steering reaction force T1 is calculated using the vehicle speed V.* Target turning reaction force T1 * The target value of the torque applied in the direction opposite to the direction of steering wheel 11 operation and generated by the reaction motor 31 is the target steering reaction force. The target steering reaction force calculation unit 191 calculates the target steering reaction force T1. * This causes its absolute value to change with the steering torque T. h The absolute value of V increases as the vehicle speed V decreases.

[0263] Axial force calculation unit 192 is based on pinion angle θ p The current I of the rotating motor 41 b Value, steering angle θ s The axial force applied to the rotating shaft 14 is calculated using the vehicle speed V, and the converted torque value (steering reaction force based on the axial force) T2 obtained by converting the calculated axial force into torque is also calculated. * .

[0264] Subtractor 193 uses the target turning reaction force T1 calculated from the target turning reaction force calculation unit 191. * Subtract the converted torque value T2 calculated by the axial force calculation unit 192 from the middle. * To calculate the steering reaction force command value T1 * .

[0265] The axial force calculation unit 192 will be described in detail below. Figure 21 As shown, the axial force calculation unit 192 includes a combined axial force calculation unit 201, a curbstone axial force calculation unit 202, a maximum value selection unit 203, and a converter 204. The combined axial force calculation unit 201 includes an angle axial force calculation unit 201A, a current axial force calculation unit 201B, and an axial force distribution calculation unit 201C.

[0266] Angular axial force calculation unit 201A based on pinion angle θ p The angular axial force AF1, which is the ideal value of the axial force applied to the rotating shaft 14, is calculated. The angular axial force calculation unit 201A uses the angular axial force mapping stored in the storage device of the control device 50 to calculate the angular axial force AF1. The angular axial force mapping is a two-dimensional mapping—where the pinion angle θ is set for the horizontal axis. p Furthermore, an angular axial force AF1 is set for the longitudinal axis, and the angular axial force mapping is limited to the pinion angle θ according to the vehicle speed V. p The relationship between the angular axial force AF1 and the angular axial force mapping. The angular axial force mapping has the following characteristics. That is, the angular axial force AF1 is set such that its absolute value changes with the pinion angle θ. p The absolute value of the [something] increases as the vehicle speed V decreases. This increases with the pinion angle θ.p As the absolute value of the axial force AF1 increases, the absolute value of the angular axial force AF1 increases linearly. The angular axial force AF1 is set to be related to the pinion angle θ. p The symbols are the same. The axial force AF1 is an axial force that does not reflect the road surface condition or the force acting on the rotating shaft 14.

[0267] The current axial force calculation unit 201B is based on the current I of the rotating motor 41. b The value of the current applied to the rotating shaft 14 is used to calculate the axial force AF2. Here, the current I of the rotating motor 41 is used to calculate the axial force AF2. b The value of the target pinion angle θ is due to the interference imposed on the road surface conditions, such as the road friction resistance of rotating wheels 16 and 16. p * Angle θ of the actual pinion p The difference between them changes. That is, the actual road surface condition applied to the rotating wheels 16 and 16 is reflected in the current I of the rotating motor 41. b The value can be determined based on the current I of the rotating motor 41. b The value is used to calculate the axial force reflecting the influence of road surface conditions. This is achieved by adjusting the current I of the rotating motor 41. b The value of AF2 is multiplied by a gain that is a coefficient based on the vehicle speed V to calculate the current axial force AF2. The current axial force AF2 is an axial force that reflects the road surface condition or the force acting on the rotating shaft 14 via the rotating wheels 16 and 16.

[0268] The axial force distribution calculation unit 201C sets the distribution ratios of the angular axial force AF1 and the current axial force AF2 based on various state variables reflecting vehicle behavior, steering state, and road surface state. The axial force distribution calculation unit 201C calculates the combined axial force AF3 by adding the values ​​obtained by multiplying the angular axial force AF1 and the current axial force AF2 by their respective set distribution ratios.

[0269] The allocation ratio can be set solely based on the vehicle speed V, which is a vehicle state variable. In this case, for example, as the vehicle speed V increases, the allocation ratio for the angular axial force AF1 is set to a larger value, while the allocation ratio for the current axial force AF2 is set to a smaller value. Conversely, as the vehicle speed V decreases, the allocation ratio for the angular axial force AF1 is set to a smaller value, while the allocation ratio for the current axial force AF2 is set to a larger value.

[0270] Curbstone axial force calculation unit 202 is based on pinion angle θ p Vehicle speed V and steering angle θ sThe axial force AF4 of the curb is calculated to limit additional steering or return steering when the rotating wheels 16 and 16 are in contact with an obstacle such as a curb. The axial force AF4 of the curb is calculated based on the idea that when the vehicle starts from a stationary state, the steering reaction force informs the driver of the contact between the rotating wheels 16 and 16 and an obstacle such as a curb. The details of the curb axial force calculation unit 202 will be described later.

[0271] The maximum value selection unit 203 receives the combined axial force AF3 calculated by the combined axial force calculation unit 201 and the curb axial force AF4 calculated by the curb axial force calculation unit 202. The maximum value selection unit 203 selects the axial force with the larger absolute value from the received combined axial force AF3 and curb axial force AF4, and sets the selected combined axial force AF3 or curb axial force AF4 as the command value T used to calculate the steering reaction force. * The final axial force AF5.

[0272] The converter 204 calculates the converted torque value T2 by converting the final axial force AF5 set by the maximum value selection unit 203 into torque. * The following will describe in detail the axial force calculation unit 202 for curb stones.

[0273] like Figure 22 As shown, the curbstone axial force calculation unit 202 includes a differentiator 202A, a determination unit 202B, a target steering angle calculation unit 202C, a subtractor 202D, and an axial force calculation unit 202E. The differentiator 202A receives the pinion angle θ calculated by the pinion angle calculation unit 61. p And by the received pinion angle θ p To calculate the angular velocity ω of the pinion by performing differentiation p .

[0274] The unit 202B receives the current I from the rotating motor 41. b The value of the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * The pinion angle θ calculated by the pinion angle calculation unit 61 p And the vehicle speed V detected by vehicle speed sensor 501. Determination unit 202B determines the target pinion angle θ based on the received value. p * pinion angle θ pThe vehicle speed V is used to determine whether the rotating wheels 16 and 16 are in contact with an obstacle such as a curb. The determining unit 202B determines that the rotating wheels 16 and 16 are in contact with an obstacle such as a curb when all four determining conditions (B1) to (B4) are met.

[0275] |Δθ p (=|θ p * -θ p |)|>θ pth (B1)

[0276] |I b |>I th (B2)

[0277] |ω p |<ω th (B3)

[0278] |V| <V th (B4)

[0279] In the given condition (B1), “Δθ p "It is the angle difference, and is determined by the angle θ from the target pinion." p * Subtract the actual pinion angle θ from the middle p And obtain. “θ pth "This is the angle difference threshold. The angle difference threshold θ" pth This design is based on the following premise: when rotating wheels 16 and 16 are in contact with an obstacle, it is difficult to rotate rotating wheels 16 and 16 to the additional rotation steering side or the return steering side. When steering wheel 11 is turned to the additional rotation steering side or the return steering side in this state, the target pinion angle θ p * As the steering angle increases and the rotation angle θ w Or pinion angle θ p It remains at a constant value. Therefore, when rotating wheels 16 and 16 are in contact with the obstacle, the target pinion angle θ p * Angle θ with the pinion p The difference between them increases with further attempts to additionally rotate the rotating wheels 16 and 16. Therefore, it can be said that with the angular difference Δθ p As the absolute value of θ increases, the likelihood of rotating wheels 16 and 16 coming into contact with obstacles increases. Therefore, the angle difference Δθ p This value indicates the probability of rotating wheels 16 and 16 coming into contact with an obstacle. Based on this, and taking into account the tolerance caused by noise from the rotation angle sensor 43, the angle difference threshold Δθ is set through experimentation or simulation. pth .

[0280] In determining condition (B2), "I" th "This is the current threshold. Current threshold I" th This design is based on the following viewpoint: When rotating wheels 16 and 16 are in contact with an obstacle, the current I of the rotating motor 41... b The absolute value increases with further attempts to additionally rotate the rotating wheels 16 and 16. Therefore, it can be said that with the rotation of the current I of the motor 41... b As the absolute value of the current increases, the likelihood of rotating wheels 16 and 16 coming into contact with obstacles increases. The current I of rotating motor 41... b The value indicates the probability of rotating wheels 16 and 16 coming into contact with an obstacle. Based on this, the current threshold I is set through experimentation or simulation. th .

[0281] In determining condition (B3), “ω p "This is the angular velocity of the pinion, and it is determined by the angle θ of the pinion." p It is obtained by differentiation. "ω" th "This is the angular velocity threshold. Angular velocity threshold ω" th This design is based on the following viewpoint: When rotating wheels 16 and 16 are in contact with an obstacle, it is difficult to make them rotate. Therefore, it can be said that with the absolute value of the rotational speed of rotating wheels 16 and 16, or the angular velocity ω of the pinion, the rotation speed increases. p As the size decreases, the likelihood of rotating wheels 16 and 16 coming into contact with obstacles increases. The angular velocity ω of the pinion... p This value also indicates the probability of rotating wheels 16 and 16 coming into contact with an obstacle. Based on this viewpoint, and taking into account the tolerance caused by noise from the rotation angle sensor 43, the angular velocity threshold ω is set through experimentation or simulation. th .

[0282] In the given condition (B4), “V” th "Vehicle speed threshold" is used as a benchmark to determine whether a vehicle is traveling at a low speed. Vehicle speed threshold V th It is set based on the vehicle speed V in the so-called low-speed zone (0 km / h to below 40 km / h), and is set to, for example, "40 km / h". Vehicle speed threshold V th It is designed based on the following viewpoint: determining whether the turning wheels 16 and 16 are in contact with an obstacle or determining whether to notify the driver of the condition of the turning wheels 16 and 16 being in contact with an obstacle at the station by rapidly changing the steering reaction force, as will be described later.

[0283] For example, when a vehicle is traveling at speed V in a medium-speed zone (40 km / h to less than 60 km / h) or a high-speed zone (equal to or greater than 60 km / h), it is conceivable that even if the driver is notified that wheels 16 and 16 have come into contact with an obstacle, the driver is too busy to notice and cannot, or can hardly, take appropriate measures such as obstacle avoidance maneuvers. Considering this situation, when the vehicle is traveling at speed V in a medium-speed or high-speed zone, it may be less necessary to notify the driver that wheels 16 and 16 have come into contact with an obstacle, and determining whether wheels 16 and 16 have come into contact with an obstacle may be useless. Therefore, in this embodiment, the condition of the vehicle traveling at speed V in a low-speed zone is set as a determining condition for determining whether wheels 16 and 16 have come into contact with an obstacle.

[0284] The determining unit 202B sets the value of flag F27 as the determination result indicating whether rotating wheels 16 and 16 are in contact with an obstacle. When it is determined that rotating wheels 16 and 16 are not in contact with an obstacle, that is, when at least one of the four determining conditions (B1) to (B4) is not met, the determining unit 202B sets the value of flag F27 to "0". When it is determined that rotating wheels 16 and 16 are in contact with an obstacle, that is, when all four determining conditions (B1) to (B4) are met, the determining unit 202B sets the value of flag F27 to "1".

[0285] When the determining unit 202B determines that the rotating wheels 16 and 16 are in contact with the obstacle, that is, when the value of the flag F27 set by the determining unit 202B is "1", the target steering angle calculation unit 202C calculates the target steering angle based on the pinion angle θ. p To calculate the target turning angle θ s * The target steering angle calculation unit 202C calculates the pinion angle θ based on the vehicle speed V using the steering angle ratio. p Converted to steering angle θ s To calculate the target turning angle θ s * .

[0286] In this embodiment, the target steering angle calculation unit 202C uses mapping M11 to calculate the target steering angle θ. s * Mapping M11 is stored in the storage device of control device 50. For example... Figure 23 As shown in the graph, mapping M11 is based on the vehicle speed V, which limits the pinion angle θ. p With the target turning angle θ s * A three-dimensional mapping of the relationship between them, and possessing the following properties. That is, as the pinion angle θ... p As the absolute value of θ increases and the vehicle speed V increases, the target steering angle θs * The absolute value increases.

[0287] When the determining unit 202B determines that the rotating wheels 16 and 16 are not in contact with the obstacle, that is, when the value of the flag F27 set by the determining unit 202B is "0", the target steering angle calculation unit 202C does not calculate the target steering angle θ. s * .

[0288] like Figure 22 As shown, when the determining unit 202B determines that the rotating wheels 16 and 16 are in contact with the obstacle, that is, when the value of the flag F27 set by the determining unit 202B is "1", the subtractor 202D calculates the angle difference Δθ. s . Angle difference Δθ s The target turning angle θ s * With steering angle θ s The difference between them, the angle difference Δθ s The target turning angle θ is calculated from the target turning angle calculation unit 202C. s * Subtract the steering angle θ calculated by the steering angle calculation unit 51 from the middle. s And obtained.

[0289] When the determining unit 202B determines that the rotating wheels 16 and 16 are not in contact with the obstacle, that is, when the value of the flag F27 set by the determining unit 202B is "0", the subtractor 202D does not calculate the angle difference Δθ. s .

[0290] Axial force calculation unit 202E is based on the angle difference Δθ calculated by subtractor 202D. s The axial force AF4 of the curbstone is calculated. The axial force calculation unit 202E uses the mapping M12 stored in the storage device of the control device 50 to calculate the axial force AF4 of the curbstone. The mapping M12 is in which an angle difference Δθ is set for the horizontal axis. s The absolute value of the axial force AF4 of the curb is set for the longitudinal axis and the angle difference Δθ is limited. s A two-dimensional mapping relating the absolute value of the axial force AF4 on the curbstone to the axial force M4. For example, mapping M12 has the following characteristics: that is, as the angle difference Δθ... s As the absolute value increases relative to "0", the curb axial force AF4 is set to be larger. The curb axial force AF4 is set based on the idea of ​​generating a steering reaction force that makes it difficult for the driver to turn the steering wheel to the side where the turning wheel contacts the obstacle.

[0291] Therefore, for example, when the steering wheel 11 turns while the wheels 16 are in contact with an obstacle such as a curb, the curb axial force calculation unit 202 calculates the curb axial force AF4. When the value of the curb axial force AF4 becomes greater than the combined axial force AF3 calculated by the combined axial force calculation unit 201, the curb axial force AF4 is set as the final axial force AF5. The converted torque value T2 obtained by converting the final axial force AF5 into torque is then calculated. * Reflected in the steering reaction force command value T * When the steering angle θ is within the range, the steering reaction force increases rapidly. Therefore, it is difficult for the driver to maintain the steering angle θ. s The steering wheel 11 is operated in the direction of increasing absolute value. Therefore, the driver can feel the end of the steering reaction force and thus be aware that the turning wheels 16 and 16 are in contact with obstacles such as curbs.

[0292] Depending on the product specifications, the steering control unit 50b can be configured to change the degree of change (i.e., rate of change) of the steering angle ratio relative to the vehicle speed V according to the steering state. For example, the steering control unit 50b according to the first embodiment maintains the rate of change of the actual change of the steering angle ratio relative to the vehicle speed V at 0% by fixing the value of the vehicle speed V during turning and holding the steering, thereby suppressing vehicle inward movement caused by deceleration during turning and holding the steering or vehicle protrusion caused by acceleration during turning and holding the steering. In this case, in order to make the steering angle θ s With rotation angle θ w and θ w Synchronization, the steering angle ratio used in the rotation control unit 50b also needs to be considered in the reaction control unit 50a.

[0293] Therefore, when this embodiment is applied to the first embodiment, the following configuration is used as the curbstone axial force calculation unit 202. For example... Figure 24 As shown, in addition to the differentiator 202A, the determination unit 202B, the target steering angle calculation unit 202C, the subtractor 202D, and the axial force calculation unit 202E, the curb axial force calculation unit 202 also includes a correction processing unit 202F. The correction processing unit 202F includes a differentiator 211, a steering determination unit 212, and a corrected vehicle speed calculation unit 213, and... Figure 4 The correction processing unit 70A shown in the first embodiment is similar.

[0294] Differentiator 211 processes the steering angle θ calculated by steering angle calculation unit 51. s The steering angular velocity ω is calculated by differentiation. The steering determination unit 212 maintains the same characteristics as... Figure 5The steering determination unit 212 shown has the same function as the steering determination unit 72 according to the first embodiment. The steering determination unit 212 is based on vehicle speed V and steering angle θ. s The steering angular velocity ω determines whether the steering wheel 11 maintains a constant steering angle θ. s And set the value of flag F0 as its determination result.

[0295] The vehicle speed calculation unit 213 has the same characteristics as... Figure 6 The corrected vehicle speed calculation unit 73 shown in the first embodiment has the same function. The corrected vehicle speed calculation unit 213 calculates the vehicle speed based on vehicle speed V and steering angle θ. s The corrected vehicle speed V is calculated by adjusting the steering angular velocity ω and the value of the sign F0. c .

[0296] Therefore, according to the eighth embodiment, in addition to the advantages of the first embodiment, the following advantages can also be obtained: The steering wheel 11 maintains a constant steering angle θ because the rotating wheels 16 and 16 contact obstacles such as curbs. s At that time, it will be used to calculate the target pinion angle θ. p * and target turning angle θ s * The final vehicle speed correction vehicle speed V c The target pinion angle θ is fixed at the vehicle speed when the steering wheel 11 is in a steering state. Therefore, the target pinion angle θ is independent of the actual value of the vehicle speed V detected by the vehicle speed sensor 501. p * and target turning angle θ s * The value remains unchanged. That is, the steering wheel 11 remains at a constant steering angle θ. s In this state, the pinion angle θ in the reaction control unit 50a is adjusted. p With the target turning angle θ s * The relationship between the steering angle θ in the rotation control unit 50b and the rotation control unit 50b s Angle θ with the target pinion p * The relationship between them is synchronized. Therefore, when the steering wheel 11 maintains a constant steering angle θ due to the contact between the turning wheels 16 and 16 with obstacles such as curbs. s At that time, the turning angle θ s and rotation angle θ w They can synchronize with each other.

[0297] Ninth Implementation Method

[0298] The steering control device according to the ninth embodiment will now be described. This embodiment essentially has the same characteristics as... Figures 1 to 7 The configuration is the same as that of the first embodiment shown. The difference between this embodiment and the first embodiment lies in the configuration of the steering reaction force command value calculation unit 52 of the reaction control unit 50a.

[0299] In the online steering system 10, the steering wheel 11 is not restricted by the rotating wheels 16 and 16. Therefore, when a certain external force is applied to the steering wheel 11 while the vehicle is powered off, the steering wheel 11 can rotate. At this time, since the rotating shaft 14 is not working, the positional relationship between the steering wheel 11 and the rotating wheels 16 and 16 may become different from the original positional relationship based on a predetermined steering angle ratio. Therefore, the control device 50 has the function of automatically adjusting the position of the steering wheel 11 as an initial operation when the vehicle is powered on again.

[0300] like Figure 25 As shown, the steering reaction force command value calculation unit 52 includes a first control unit 52A, a second control unit 52B, a determination unit 52C, and a switch 52D. The first control unit 52A performs normal reaction control to generate a value based on the steering torque T through the drive control of the reaction motor 31. h The first control unit 52A includes a target steering reaction force calculation unit 301, an axial force calculation unit 302, and a subtractor 303.

[0301] Target steering reaction force calculation unit 301 is based on steering torque T h The target steering reaction force T1 is calculated using the vehicle speed V. * Target turning reaction force T1 * The target value of the steering reaction force is to be generated by the reaction motor 31. The target steering reaction force calculation unit 301 calculates the target steering reaction force T1. * This causes its absolute value to change with the steering torque T. h The absolute value of V increases as the vehicle speed V decreases.

[0302] Axial force calculation unit 302, for example, is based on pinion angle θ p and the current I of the rotating motor 41 b The value is used to calculate the axial force applied to the rotating shaft 14, and the converted torque value (i.e., the steering reaction force based on the axial force) T2 obtained by converting the calculated axial force into torque is also calculated. * .

[0303] Subtractor 303 uses the target turning reaction force T1 calculated from the target turning reaction force calculation unit 301. *Subtract the converted torque value T2 calculated by the axial force calculation unit 302 from the middle. * To calculate the steering reaction force command value T3 * .

[0304] The second control unit 52B performs an automatic adjustment process to adjust the rotational position of the steering wheel 11. The adjustment process is a process that synchronizes the positional relationship between the steering wheel 11 and the rotating wheels 16 with the original positional relationship based on a predetermined steering angle ratio when the vehicle is switched from a powered-off state to a powered-on state.

[0305] The second control unit 52B includes a target steering angle calculation unit 311 and a steering angle feedback control unit 312. The target steering angle calculation unit 311 is based on the pinion angle θ calculated by the pinion angle calculation unit 61. p To calculate the target turning angle θ s * The target steering angle calculation unit 311 calculates the target steering angle based on the vehicle speed V and the rotation angle θ. w With steering angle θ s The ratio of the steering angles is determined by the pinion angle θ. p Converted to steering angle θ s To calculate the target turning angle θ s * In this embodiment, the target steering angle calculation unit 311 uses the mapping M13 stored in the storage device of the control device 50 to calculate the target steering angle θ. s * .

[0306] like Figure 26 As shown in the graph, mapping M13 is based on the vehicle speed V, which limits the pinion angle θ. p With the target turning angle θ s * A three-dimensional mapping of the relationship between them, and possessing the following properties. That is, as the pinion angle θ... p As the absolute value of θ increases and the vehicle speed V increases, the target steering angle θ s * The absolute value increases.

[0307] Steering angle feedback control unit 312 receives the target steering angle θ calculated by target steering angle calculation unit 311. s * and the steering angle θ calculated by the steering angle calculation unit 51 s The steering angle feedback control unit 312 executes the steering angle θ s Feedback control makes the steering angle θ s Matching the target steering angle θ s* To calculate the steering reaction force command value T4 * .

[0308] When the vehicle is powered on and the position of the steering wheel 11 needs to be adjusted but the adjustment has not yet been completed, the determination unit 52C sets the value of flag F28 to "0". When the vehicle is powered on and the position of the steering wheel 11 needs to be adjusted and the adjustment has been completed, or when the position of the steering wheel 11 does not need to be adjusted, the determination unit 52C sets the value of flag F28 to "1".

[0309] When the vehicle switches from the started state to the off state, the determining unit 52C will determine the previously calculated steering angle θ s The reference steering angle θ0 is stored in the vehicle's storage device. The reference steering angle θ0 serves as a reference for determining whether the steering wheel 11 has been rotated during the period when the vehicle is in the off state. When the vehicle switches from the off state to the start state, the determining unit 52C uses the steering angle θ0 calculated immediately after the vehicle starts. s The steering wheel 11 position is determined by comparing it with a reference steering angle θ0 stored in the vehicle's storage device.

[0310] When θ is the steering angle immediately following the vehicle being turned off. s The reference steering angle θ0 and the steering angle θ immediately after the vehicle is powered on again. s When they are equal, the determining unit 52C determines the position where the steering wheel 11 does not need to be adjusted. This is when the steering angle θ is immediately following the vehicle being turned off. s The reference steering angle θ0 and the steering angle θ immediately after the vehicle is powered on again. s When they are not equal, the determining unit 52C determines the position of the steering wheel 11 that needs to be adjusted.

[0311] Switch 52D receives the steering reaction force command value T3 calculated by the first control unit 52A. * and the steering reaction force command value T4 calculated by the second control unit 52B. * As a data input, switch 52D receives the value of flag F28 set by determination unit 52C as a control input.

[0312] Switch 52D selects the steering reaction force command value T3 calculated by the first control unit 52A based on the value of flag F28. * and the steering reaction force command value T4 calculated by the second control unit 52B. * One of them is used as the steering reaction force command value T *When the value of flag F28 is "0", switch 52D selects the steering reaction force command value T4 calculated by the second control unit 52B. * As the final steering reaction force command value T5 * When the value of flag F28 is "1", switch 52D selects the steering reaction force command value T3 calculated by the first control unit 52A. * As the final steering reaction force command value T5 * .

[0313] According to this configuration, based on whether the rotational position of the steering wheel 11 needs to be adjusted, it switches between normal reaction control executed by the first control unit 52A and control for adjusting the rotational position of the steering wheel 11 executed by the second control unit 52B. For example, when the steering angle θ s If the timeframe for power restoration after a vehicle power outage remains unchanged, when the vehicle is powered back on, the system will begin to operate based on the steering torque T. h The normal reaction control generates steering reaction force. For example, when the steering wheel 11 is rotated counterclockwise by a predetermined angle during a period when the vehicle is powered off, when the vehicle is powered back on, the rotational position of the steering wheel 11 is adjusted. That is, the steering wheel 11 is rotated clockwise by a predetermined angle through the drive control of the reaction motor 31. Therefore, the positional relationship between the steering wheel 11 and the rotating wheels 16 returns to the original positional relationship based on the predetermined steering angle ratio.

[0314] Depending on the product specifications, the steering control unit 50b can be configured to change the degree of change (i.e., rate of change) of the steering angle ratio relative to the vehicle speed V according to the steering state. For example, the steering control unit 50b according to the first embodiment maintains the rate of change of the actual change of the steering angle ratio relative to the vehicle speed V at 0% by fixing the value of the vehicle speed V during steering and holding the steering, thereby suppressing vehicle inward movement caused by deceleration during steering and holding the steering or vehicle protrusion caused by acceleration during steering and holding the steering. In this case, in order to adjust the steering angle θ by performing the process of adjusting the rotational position of the steering wheel 11... s With rotation angle θ w and θ w Synchronization, the steering angle ratio used in the rotation control unit 50b also needs to be considered in the reaction control unit 50a.

[0315] Therefore, when this embodiment is applied to the first embodiment, the following configuration is used as the second control unit 52B. That is, as by Figure 25 As indicated by the two dashed lines, the second control unit 52B includes a correction processing unit 313 that performs the process of correcting the vehicle speed V. The correction processing unit 313 has... Figure 4 The correction processing unit 313 is configured the same as that of the correction processing unit 70A according to the first embodiment. The correction processing unit 313 is based on the steering state of the steering wheel 11, i.e., whether the steering wheel 11 remains at a constant steering angle θ. s To calculate the corrected vehicle speed V c .

[0316] Therefore, according to the ninth embodiment, in addition to the advantages of the first embodiment, the following advantages can also be obtained: Even when the process of adjusting the rotational position of the steering wheel 11 is performed as the initial operation at the time of vehicle startup and while the steering wheel 11 is held, the pinion angle θ in the reaction control unit 50a is maintained. p With the target turning angle θ s * The relationship between the steering angle θ in the rotation control unit 50b and the rotation control unit 50b s Angle θ with the target pinion p * The relationship between them is synchronized. Therefore, the steering angle θ can be made... s and rotation angle θ w They are synchronized with each other.

[0317] Tenth Implementation Method

[0318] The steering control device according to the tenth embodiment will now be described. This embodiment essentially has the same... Figures 1 to 7 The configuration is the same as the first embodiment shown. The difference between this embodiment and the first embodiment is that it provides an autonomous driving function.

[0319] Autonomous driving systems that enable automatic driving functions, allowing various driving support functions to replace driving, or systems used to improve vehicle safety or convenience, can be installed in vehicles. In such cases, coordinated control is performed in such vehicles by a control unit 50 and control units of onboard systems other than the control unit 50. Coordinated control is a technology that allows control units of multiple types of onboard systems to coordinate with each other to control the movement of the vehicle. For example, a main control unit 500 that integrates control units of various onboard systems is installed in the vehicle. The main control unit 500 obtains the optimal control method based on the current vehicle state and commands each onboard control unit to perform control based on the obtained control method.

[0320] The main control unit 500 intervenes in the steering control performed by the control unit 50. The main control unit 500 switches its automatic driving control function between on (enabled) and off (disabled) by operating a switch (not shown) located on the driver's seat or similar object. The automatic driving control function includes driver support control functions designed to enhance vehicle safety or convenience.

[0321] For example, the main control unit 500 calculates the additional target pinion angle θ. pa * This serves as the command value used to guide the vehicle within the target lane. Additional target pinion angle θ. pa * This is the target value of the pinion angle (the angle to be added to the current pinion angle) required for the vehicle to travel along the lane based on its current driving or steering state. Control unit 50 uses the additional target pinion angle θ calculated by main control unit 500. pa * To control the reaction motor 31 and the rotary motor 41.

[0322] like Figure 27 As shown, in addition to the steering angle calculation unit 51, the steering reaction force command value calculation unit 52, and the power supply control unit 53, the reaction control unit 50a also includes a target steering angle calculation unit 55. The target steering angle calculation unit 55 receives the additional target pinion angle θ calculated by the main control device 500. pa * And the vehicle speed V detected by vehicle speed sensor 501, and based on the received additional target pinion angle θ pa * The additional target steering pinion angle θ is calculated using the vehicle speed V. sa * The target steering angle calculation unit 55 calculates the target steering angle based on the vehicle speed V and the rotation angle θ. w With steering angle θ s The ratio of the steering angles is determined by adding the target pinion angle θ. pa * Convert to steering angle to calculate the additional target steering pinion angle θ sa * In this embodiment, the target steering angle calculation unit 55 uses the mapping M14 stored in the storage device of the control device 50 to calculate the additional target steering pinion angle θ. sa * .

[0323] like Figure 28 As shown in the graph, mapping M14 is based on the vehicle speed V, which limits the additional target pinion angle θ. pa * With the additional target steering pinion angle θ sa * A three-dimensional mapping of the relationship between them, and possessing the following properties. That is, with the addition of the target pinion angle θ... pa * As the absolute value of θ increases and the vehicle speed V increases, the additional target steering pinion angle θ... sa* The absolute value increases.

[0324] like Figure 27 As shown, the steering reaction force command value calculation unit 52 uses the steering torque T detected by the torque sensor 34. h The steering angle θ calculated by the steering angle calculation unit 51 s And the additional target steering pinion angle θ calculated by the target steering angle calculation unit 55. sa * To calculate the steering reaction force command value T * When based on the steering reaction force command value T * When power is supplied to the reaction motor 31, the rotational and steering reaction force command value T of the reaction motor 31 is... * The corresponding angle. Details of the steering reaction force command value calculation unit 52 will be described later.

[0325] In addition to the pinion angle calculation unit 61, the target pinion angle calculation unit 62, the pinion angle feedback control unit 63, and the power supply control unit 64, the rotation control unit 50b also includes an adder 66. The adder 66 calculates the additional target pinion angle θ by the main control unit 500. pa * The target pinion angle θ calculated by the target pinion angle calculation unit 62 p * The values ​​are added together to calculate the command value T used to calculate the pinion angle. p * The final target pinion angle θ pfin * Adder 66 will calculate the final target pinion angle θ. pfin * Supply is provided to the pinion angle feedback control unit 63. The pinion angle feedback control unit 63 controls the pinion angle θ by executing... p The feedback control ensures that the actual pinion angle θ calculated by the pinion angle calculation unit 61 is accurate. p Meets the final target pinion angle θ pfin * To calculate the pinion angle command value T p * When based on the pinion angle command value T p * When power is supplied to the rotating motor 41, the rotating motor 41 rotates in accordance with the angle command value T of the pinion gear. p * The corresponding angle.

[0326] The following will describe in detail an example of the steering reaction force command value calculation unit 52. For example... Figure 29 As shown, the steering reaction force command value calculation unit 52 includes an adder 401, a target steering torque calculation unit 402, a torque feedback control unit 403, an axial force calculation unit 404, a target steering angle calculation unit 405, a steering angle feedback control unit 406, and an adder 407.

[0327] Adder 401 inputs the first steering reaction force command value T calculated by torque feedback control unit 403. 11 * The steering torque T detected by torque sensor 34 h The input torque T is calculated by adding them together as the torque applied to the steering shaft 12. in * .

[0328] The target steering torque calculation unit 402 is based on the input torque T calculated by the adder 401. in * To calculate the target steering torque T h * Target steering torque T h * The steering torque T to be applied to steering wheel 11 h The target value. The target steering torque calculation unit 402 calculates the target steering torque T. h * This causes its absolute value to change with the input torque T. in * The absolute value increases as the absolute value increases.

[0329] The torque feedback control unit 403 receives the steering torque T detected by the torque sensor 34. h And the target steering torque T calculated by the target steering torque calculation unit 402 h * The torque feedback control unit 403 controls the steering torque T. h Feedback control enables the steering torque T detected by torque sensor 34 to be... h Meets the target steering torque T h * To calculate the first steering reaction force command value T 11 * .

[0330] Axial force calculation unit 404, for example, is based on pinion angle θ p The current I of the rotating motor 41 bThe axial force acting on the rotating shaft 14 is calculated using the value of the axial force and the vehicle speed V, and the converted torque value (i.e., the steering reaction force based on the axial force) T is calculated by converting the calculated axial force into torque. af .

[0331] The target steering angle calculation unit 405 receives the steering torque T detected by the torque sensor 34. h The first steering reaction force command value T calculated by the torque feedback control unit 403 11 * The converted torque value T calculated by the axial force calculation unit 404 af And the vehicle speed V detected by vehicle speed sensor 501. Target steering angle calculation unit 405 calculates the target steering angle based on the received steering torque T. h First steering reaction force command value T 11 * , conversion torque value T af And the vehicle speed V is used to calculate the target steering angle θ of the steering wheel 11. s * .

[0332] The target steering angle calculation unit 405 calculates the target steering angle by taking the input torque T. in * Subtract the conversion torque value T from the middle af The final input torque T for steering wheel 11 is calculated based on the steering reaction force of the axial force. in * Input torque T in * It is the first steering reaction force command value T 11 * and steering torque T h The sum of the values. The target steering angle calculation unit 405 is based on the final input torque T. in * The target steering angle θ is calculated using an ideal model represented by the following expression (A7). s * The ideal model is based on the premise that the steering wheel 11 is mechanically connected to the steering wheels 16 and 16, and the steering system is based on the input torque T through prior experiments, etc. in * The steering angle of the steering wheel 11 corresponding to the ideal rotation angle is obtained by modeling.

[0333] T in * =Jθ s +Cθ s '+Kθ s …(A7)

[0334] Here, "J" represents the coefficient of inertia corresponding to the moment of inertia of the steering wheel 11 and steering shaft 12, "C" represents the viscosity coefficient (coefficient of friction) corresponding to the friction between the rotating shaft 14 and the housing, and "K" represents the spring coefficient when the steering wheel 11 and steering shaft 12 are considered as springs. The viscosity coefficient C and the coefficient of inertia J have values ​​based on the vehicle speed V. "θ" s "" represents the steering angle θ s The second derivative value of θ, and "θ s '" represents the steering angle θ s The first-order differential value.

[0335] When the automatic driving control function is activated and the main control unit 500 calculates the additional target pinion angle θ... pa * At that time, the additional target steering pinion angle θ calculated by the target steering angle calculation unit 55 will be used. sa * The target steering angle θ is added to the target steering angle calculation unit 405. s * .

[0336] Steering angle feedback control unit 406 receives the steering angle θ calculated by steering angle calculation unit 51. s and the target turning angle θ calculated by the target turning angle calculation unit 405 s * The steering angle feedback control unit 406 controls the steering angle θ. s The feedback control makes the actual steering angle θ calculated by the steering angle calculation unit 51... s Matching the target steering angle θ s * To calculate the second steering reaction force command value T 12 * .

[0337] Adder 407 inputs the second steering reaction force command value T calculated by steering angle feedback control unit 406. 12 * The first steering reaction force command value T calculated by the torque feedback control unit 403 11 * The values ​​are added together to calculate the steering reaction force command value T. * .

[0338] According to this configuration, when the automatic driving control function is activated and the main control unit 500 calculates the additional target pinion angle θ... pa * At that time, based on the vehicle speed V and the steering angle ratio, the additional target pinion angle θ is used. pa* Convert to steering angle to calculate the additional target steering pinion angle θ sa * Therefore, the steering angle θ is [value missing] during manual driving performed by the driver and during automatic driving control performed by the main control unit 500. s The change, i.e. the movement of the steering wheel 11, can be set to be the same.

[0339] Depending on the product specifications, the steering control unit 50b can be configured to change the degree of change (i.e., rate of change) of the steering angle ratio relative to the vehicle speed V according to the steering state. For example, the steering control unit 50b according to the first embodiment maintains the rate of change of the actual change of the steering angle ratio relative to the vehicle speed V at 0% by fixing the value of the vehicle speed V during turning and holding the steering, thereby suppressing vehicle inward movement caused by deceleration during turning and holding the steering or vehicle protrusion caused by acceleration during turning and holding the steering. In this case, in order to make the steering angle θ s With rotation angle θ w and θ w Synchronization, the steering angle ratio used in the rotation control unit 50b also needs to be considered in the reaction control unit 50a.

[0340] Therefore, when this embodiment is applied to the first embodiment, the following configuration is used as the reaction control unit 50a. That is, as by Figure 27 As indicated by the two dashed lines, the reaction control unit 50a includes a correction processing unit 57 that performs the process of correcting the vehicle speed V. The correction processing unit 57 has... Figure 4 The correction processing unit 57 is configured the same as that of the correction processing unit 70A according to the first embodiment. The correction processing unit 57 is based on the steering state of the steering wheel 11, i.e., whether the steering wheel 11 maintains a constant steering angle θ. s To calculate the corrected vehicle speed V c .

[0341] The main control unit 500 calculates the additional target pinion angle θ. pa * Additional target pinion angle θ pa * It needs to be added to the current pinion angle θ p The angle, however, for example, the angle θ of the target pinion. p * The ideal pinion angle θ required for a vehicle to travel along the lane can be calculated. p The target value.

[0342] Therefore, according to the tenth embodiment, in addition to the advantages of the same as those of the first embodiment, the following advantages can also be obtained. Even when the steering wheel 11 is held during automatic driving control performed by the main control unit 500, the additional target pinion angle θ in the reaction control unit 50a is also increased. pa * With the additional target steering pinion angle θ sa * The relationship between the steering angle θ in the rotation control unit 50b and the rotation control unit 50b s Angle θ with the target pinion p * The relationship between them is synchronized. Therefore, the steering angle θ can be made... s and rotation angle θ w They are synchronized with each other.

[0343] Other implementation methods

[0344] The previously mentioned implementation method can be modified as follows. The eighth implementation method can be applied to the second implementation method. That is, the curbstone axial force calculation unit 202 uses a method based on steering torque T. h Calculated estimated steering angle θ es And the estimated turning angle θ es The estimated steering angular velocity ω is obtained by differentiation. es Instead of steering angle θ s And the steering angular velocity ω. In the same manner as the eighth embodiment, the ninth and tenth embodiments can be applied to the second embodiment.

[0345] The eighth embodiment can be applied to the third embodiment. In this case, the curbstone axial force calculation unit 202 is configured as follows. That is, as... Figure 10 As described in square brackets, the curbstone axial force calculation unit 202 includes a speed-increase ratio calculation unit 221, a correction processing unit 222, and a divider 223. The speed-increase ratio calculation unit 221 has the same characteristics as... Figure 10 The speed ratio calculation unit 111 shown in the third embodiment has the same function. The correction processing unit 222 has the same function as... Figure 10 The correction processing unit 120 shown in the third embodiment has the same function. The correction processing unit 120 calculates the corrected growth rate ratio ν by performing a correction process on the growth rate ratio ν calculated by the growth rate ratio calculation unit 221. c The divider 223 calculates the pinion angle θ by the pinion angle calculation unit 61. p Divided by the correction growth rate ν calculated by the correction processing unit 222 c To calculate the target turning angle θ s *In the same manner as the eighth embodiment, the ninth and tenth embodiments can be applied to the third embodiment.

[0346] The eighth embodiment can be applied to the fourth embodiment. In this case, the curbstone axial force calculation unit 202 is provided with a function similar to... Figures 11 to 14 The correction processing unit 70A shown is according to the fourth embodiment, instead of Figure 24 The correction processing unit shown is a correction processing unit with the same configuration as the correction processing unit 202F. When using... Figure 15 When the configuration shown in the fifth embodiment is used as the rotation determination unit 131 of the correction processing unit 70A, it employs the same... Figure 15 The rotation determination unit shown is configured identically to the rotation determination unit 131 according to the fifth embodiment, serving as the correction processing unit in the curbstone axial force calculation unit 202. When using... Figure 16 and Figure 18 When the rotation determination unit 131, deceleration determination unit 132, and acceleration determination unit 133 of the correction processing unit 70A are configured according to the sixth embodiment, the method adopted is similar to Figure 15 The same configuration shown in the fifth embodiment serves as the rotation determination unit, deceleration determination unit, and acceleration determination unit in the correction processing unit 202 for the curbstone axial force calculation unit. In the same manner as the eighth embodiment, the ninth and tenth embodiments can be applied to the fourth through sixth embodiments.

[0347] The eighth embodiment can be applied to the seventh embodiment. In this case, the curbstone axial force calculation unit 202 is provided with a function similar to... Figure 20 The correction processing unit 180B shown is according to the seventh embodiment, instead of Figure 24 The correction processing unit 202F shown is configured with the same correction processing unit as the seventh embodiment. The ninth and tenth embodiments can be applied to the seventh embodiment in the same manner as the eighth embodiment.

[0348] Other implementation methods

[0349] In the aforementioned embodiments, a clutch can be provided in the steering system 10. In this case, as by Figure 1As indicated by the two dashed lines, the steering shaft 12 and the pinion shaft 13 are connected to each other via a clutch 21. The clutch 21 is an electromagnetic clutch that performs the engagement / disengagement of power by controlling the power supply to the excitation coil. The control device 50 performs the engagement / disengagement control of the clutch 21, switching it between engagement and disengagement. When the clutch 21 is disengaged, the power transmission between the steering wheel 11 and the rotating wheels 16 is mechanically cut off. When the clutch 21 is engaged, the power transmission between the steering wheel 11 and the rotating wheels 16 is mechanically established.

[0350] In the aforementioned embodiments, the steering system 10 can be a laterally independent steering system that independently rotates the left and right wheels relative to the vehicle's direction of travel. The steering system 10 can also be configured as a four-wheel independent steering system that independently rotates all four wheels of a four-wheel drive vehicle.

Claims

1. A steering control device (50) configured to control a rotary motor that generates a rotational force, the rotational force being used to rotate a rotating wheel to which power transmission to and from a steering wheel is interrupted, the steering control device (50) being characterized in that it comprises: A first processor is configured to change the steering angle ratio according to the vehicle speed by controlling the rotary motor, the steering angle ratio being the ratio of the rotation angle of the rotary wheel to the steering angle of the steering wheel. as well as A second processor is configured to change the degree of variation of the steering angle ratio relative to the vehicle speed based on the steering state or vehicle state. The first processor is configured to calculate a target rotation angle of the shaft as the rotating wheel rotates, based on the vehicle speed and the steering angle of the steering wheel, and to control the rotating motor so that the shaft rotates to the target rotation angle. The second processor is configured to fix the value of the vehicle speed used to calculate the target rotation angle when the steering wheel is held at a constant steering angle relative to the neutral position, and is configured to slowly change the value of the vehicle speed used to calculate the target rotation angle to the current value of the vehicle speed detected by the vehicle speed sensor when the state held by the steering wheel is released.

2. The steering control device (50) according to claim 1, characterized in that, A reaction motor configured to control the generation of a steering reaction force, which is a torque applied to the steering wheel in the opposite direction to the steering direction. Also includes: A third processor (202C) is configured to convert the rotation angle of the shaft, which rotates with the rotation of the rotating wheel, into a target steering angle of the steering wheel based on the vehicle speed and the steering angle ratio, wherein the steering angle ratio is the ratio of the rotation angle of the rotating wheel to the steering angle of the steering wheel; and A fourth processor (202F) is configured to change the degree of change of the steering angle ratio relative to the change in the vehicle speed used to calculate the target steering angle by performing the same processing as that performed by the second processor.

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