Steering control device

Abstract

A steering control device (50) controls a reaction force motor that generates a steering reaction force applied to a steering wheel with power transmission between the steering wheel and a turning wheel being cut off. The steering control device (50) includes a first processor (101) configured to change a virtual operation range of the steering wheel according to a steering state or a vehicle state by controlling the reaction force motor, and a second processor configured to change a degree of change in the virtual operation range of the steering wheel according to the steering state or the vehicle state when an operation position of the steering wheel reaches a position near a limit position of the virtual operation range.

Description

BACKGROUND 1. TECHNICAL FIELD

[0002] The present application relates to a steering control device.

[0003] 2. DESCRIPTION OF RELATED ART

[0004] A so-called steer-by-wire steering system is known in which a power transmission path between a steering wheel and a steered wheel is cut off. The steering system includes a reaction motor that is a source of a steering reaction force applied to a steering shaft and a turning motor that is a source of a turning force that turns the steered wheel. When the vehicle is running, a control device of the steering system generates the steering reaction force using the reaction motor and turns the steered wheel using the turning motor. It is desirable to improve the steering characteristics of such a steering system.

[0005] For example, in view of improvement of the steering characteristics, a control device described in Japanese Unexamined Patent Application Publication No. 2013-209026 (JP 2013-209026 A) changes a steering angle ratio in accordance with a vehicle speed. The steering angle ratio is a ratio of a turning angle of the steered wheel to a steering angle of the steering wheel. The steering angle ratio is set to become a larger value as the vehicle speed increases. As the steering angle ratio decreases, the turning angle of the steered wheel changes more quickly when the steering wheel is operated. As the steering angle ratio increases, the turning angle of the steered wheel changes more slowly when the steering wheel is operated.

[0006] Therefore, when the vehicle enters a garage or the like in a low speed region, a larger turning amount is obtained with respect to the steering amount of the steering wheel, thereby ensuring the operability of the vehicle. When the vehicle performs a lane change or the like in a high speed region, the turning amount becomes small with respect to the steering amount of the steering wheel, thereby ensuring the running stability of the vehicle.

[0007] A control device described in Japanese Unexamined Patent Application Publication No. 2004-130971 (JP 2004-130971 A) has a function of virtually limiting the operation range of the steering wheel. When the steering angle of the steering wheel reaches a threshold value, the control device rapidly increases the steering reaction force generated by the reaction motor. When the steering reaction force is rapidly increased, the driver has difficulty in operating the steering wheel in a direction in which the absolute value of the steering angle increases. Therefore, it is possible to virtually change the operation range of the steering wheel.

[0008] The control device described in JP 2004-130971 A changes the allowable range of the steering angle (i.e., thresholds as the upper and lower limits of the allowable range) in addition to changing the steering angle ratio based on vehicle speed. For example, when traveling at high speeds, the control device limits the allowable range of the steering angle, making it narrower and setting the value of the steering angle ratio (=turning amount / steering amount) to a larger value. At high speeds, a more stable and comfortable steering feel can be achieved by preventing oversteering or sudden steering. For example, when turning during actions typically performed at very low speeds, such as parking or entering a garage, the control device described in JP 2004-130971A limits the allowable range of the steering angle, making it narrower and setting the value of the steering angle ratio to a smaller value. The turning wheels can then turn a larger amount with a smaller steering amount. Summary of the Invention

[0009] In general control devices in the prior art, including the control device described in JP 2004-130971 A, which have the function of changing the allowable range of steering angle according to vehicle speed, there is a concern that, for example, when the vehicle is decelerated or accelerated while the steering wheel operation position has reached the limit of its virtual operating range, the limit position of the virtual operating range changes with the vehicle speed. Therefore, there is a concern that unwanted steering behavior may occur.

[0010] For example, when a vehicle is decelerated from the point where the steering wheel is already at its virtual limit of operation, the steering wheel's operating range narrows as the vehicle speed decreases. It is conceivable that, due to the steering reaction force generated as the operating range narrows, the steering wheel will be rotated so that it is pushed back in the opposite direction to the current steering direction. Because the steering wheel is unintentionally pushed back, the driver may feel discomfort (a feeling of resistance).

[0011] When a vehicle accelerates from the point where the steering wheel is already at its virtual limit, the steering wheel's operating range widens with increasing speed. That is, since the current limit of the operating range is no longer considered the limit, the steering wheel can be turned further in the current steering direction. Because the driver does not feel a steering reaction force through the steering wheel, they may experience a sensation of what is known as steering error.

[0012] The present invention provides a steering control device that can suppress changes in steering feel that are not desired by the driver.

[0013] According to one aspect of the present invention, a steering control device is provided. The steering control device controls a reaction motor that generates a steering reaction force applied to a steering wheel, thereby cutting off power transmission between the steering wheel and the rotating wheels. The steering control device includes: a first processor configured to: change the virtual operating range of the steering wheel according to a steering state or vehicle state by controlling the reaction motor; and a second processor configured to: change the degree of change of the virtual operating range of the steering wheel according to the steering state or vehicle state when the operating position of the steering wheel reaches a position near the limit of the virtual operating range.

[0014] This configuration allows the virtual operating range of the steering wheel to change more appropriately based on the steering or vehicle status. Therefore, it can suppress unwanted changes in steering behavior by the driver.

[0015] In this steering control device, a first processor can be configured to calculate the limit value of the virtual operating range of the steering wheel based on the vehicle speed. A second processor can be configured to fix the vehicle speed value used to calculate the limit value when the steering wheel operation position reaches a position near the limit of the virtual operating range.

[0016] With this configuration, when the steering wheel's operating position reaches near the limit of the virtual operating range, the vehicle speed used to calculate the limit value of the virtual operating range is fixed. Therefore, the limit value of the virtual operating range of the steering wheel does not change with actual changes in vehicle speed. This helps suppress unwanted changes in the driver's steering behavior.

[0017] In this steering control device, a first processor can be configured to calculate the limit value of the virtual operating range of the steering wheel by dividing the rotation angle of the shaft that rotates with the rotation of the steering wheel by the speed-increasing ratio between the steering wheel and the shaft, calculated based on the vehicle speed. A second processor can be configured to limit the change per unit time of the speed-increasing ratio used to calculate the limit value when the steering wheel's operating position reaches a position near the limit of the virtual operating range.

[0018] This configuration limits the rate of change per unit time of the growth rate used to calculate the limit value of the virtual steering range when the steering wheel's operating position approaches the limit. Therefore, it slows down the change in the limit value of the virtual steering range relative to the actual change in vehicle speed. Consequently, it suppresses unwanted changes in the driver's steering behavior.

[0019] In this steering control device, a first processor can be configured to calculate the limits of the virtual operating range of the steering wheel based on the vehicle speed. A second processor can be configured to limit the variation of the limits calculated by the first processor per unit time when the steering wheel is maintained at a constant steering angle relative to its neutral position.

[0020] With this configuration, when the steering wheel is held at a constant steering angle relative to its neutral position, the change per unit time in the limit value of the virtual operating range of the steering wheel calculated by the first processor is limited. Therefore, the degree of change in the limit value of the virtual operating range of the steering wheel relative to the actual change in vehicle speed can be mitigated. Thus, when the steering wheel is held at a constant steering angle relative to its neutral position, changes in steering behavior undesirable to the driver can be suppressed.

[0021] The steering control device may further include a third processor configured to calculate a limiting axial force reflected in the steering reaction force based on a target rotation angle of the shaft that rotates with the operation of the shaft that rotates the steering wheel and the vehicle speed, to virtually limit the operation of the steering wheel, with the limiting axial force being the axial force of the shaft. A second processor may be configured to limit the variation of the limiting axial force calculated by the third processor per unit time when the steering wheel operation position reaches a position near the limit of the virtual operation range.

[0022] With this configuration, when the steering wheel is positioned near the limit of the virtual operating range, the change in the limiting axial force per unit time, calculated by the third processor, is restricted. Therefore, the degree of variation in the limiting axial force relative to vehicle speed, i.e., the degree of variation in the steering reaction force relative to vehicle speed, can be mitigated. Consequently, unwanted changes in steering behavior by the driver can be suppressed.

[0023] In this steering control device, the second processor can be configured to: when the steering wheel operation position moves away from the position near the limit of the virtual operation range, the value of the vehicle speed used to calculate the limit of the virtual operation range of the steering wheel is slowly changed to the current value of the vehicle speed detected by the vehicle speed sensor.

[0024] This configuration suppresses sudden changes in the steering wheel's virtual operating range limits when those limits return to their original values ​​based on the current vehicle speed. Therefore, it can suppress unwanted changes in the driver's steering behavior.

[0025] In this steering control device, the second processor can be configured to: when the steering wheel's operating position moves away from the position near the limit of the virtual operating range, the value of the growth rate ratio used to calculate the limit value of the virtual operating range of the steering wheel is slowly changed to the current value of the growth rate ratio calculated by the first processor.

[0026] This configuration suppresses sudden changes in the steering wheel's virtual operating range limits when these limits return to their original values ​​based on the current vehicle speed. Therefore, it can suppress unwanted changes in the driver's steering behavior.

[0027] In this steering control device, the second processor can be configured to: when the state in which the steering wheel is held at a constant steering angle relative to the neutral position of the steering wheel is released, slowly change the limit value of the virtual operating range of the steering wheel to the current limit value calculated by the first processor.

[0028] This configuration suppresses sudden changes in the steering wheel's virtual operating range limits when these limits return to their original values ​​based on the current vehicle speed. Therefore, it can suppress unwanted changes in the driver's steering behavior.

[0029] In this steering control device, the second processor can be configured to: when the steering wheel operation position becomes far away from the position near the limit of the virtual operation range, slowly change the value of the limiting axial force reflected in the steering reaction force to the current limiting axial force calculated by the third processor.

[0030] With this configuration, sudden changes in the limiting axial force are suppressed when the value of the limiting axial force reflected in the steering reaction force returns to its original value based on the current vehicle speed. Therefore, changes in steering behavior that are not desired by the driver can be suppressed.

[0031] The steering control device according to the invention can suppress changes in steering feel that are not desired by the driver. Attached Figure Description

[0032] 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 the same symbols denote the same elements, and in the drawings:

[0033] 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;

[0034] Figure 2 This is a block diagram showing the control device according to the first embodiment;

[0035] Figure 3It 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;

[0036] Figure 4 This is a block diagram showing the steering reaction force command value calculation unit according to the first embodiment;

[0037] Figure 5 This is a block diagram showing the limiting axial force calculation unit according to the first embodiment;

[0038] Figure 6 This is a block diagram showing the correction processing unit of the limiting axial force calculation unit according to the first embodiment;

[0039] Figure 7 This is a block diagram showing the end-determining unit according to the first embodiment;

[0040] Figure 8 This is a block diagram showing the vehicle speed calculation unit according to the first embodiment;

[0041] Figure 9 This is a block diagram showing the upper limit calculation unit and the lower limit calculation unit according to the first embodiment;

[0042] Figure 10 It is a front view of the steering wheel of a vehicle equipped with a steering control device according to the first embodiment, showing steering behavior;

[0043] Figure 11 This is a block diagram showing the main parts of the control device according to the second embodiment;

[0044] Figure 12 This is a block diagram showing the main parts of the limiting axial force calculation unit according to the third embodiment;

[0045] Figure 13 This is a block diagram showing the correction processing unit according to the fourth embodiment;

[0046] Figure 14 This is a block diagram showing the turning determination unit according to the fourth embodiment;

[0047] Figure 15 This is a block diagram showing the deceleration determination unit according to the fourth embodiment;

[0048] Figure 16 This is a block diagram showing the acceleration determination unit according to the fourth embodiment;

[0049] Figure 17 This is a block diagram showing the main parts of the control device according to the fifth embodiment;

[0050] Figure 18This is a block diagram showing the end-determining unit according to the fifth embodiment;

[0051] Figure 19 This is a block diagram showing the turning determination unit according to the sixth embodiment;

[0052] Figure 20 This is a perspective view of a vehicle wheel according to the seventh embodiment, showing the axial component of the tire force;

[0053] Figure 21 This is a block diagram showing the turning determination unit according to the seventh embodiment;

[0054] Figure 22 This is a block diagram showing the deceleration determination unit according to the seventh embodiment;

[0055] Figure 23 This is a block diagram showing the acceleration determination unit according to the seventh embodiment;

[0056] Figure 24 This is a block diagram showing the limiting axial force calculation unit according to the eighth embodiment;

[0057] Figure 25 This is a block diagram showing the steering reaction force command value calculation unit according to the ninth embodiment;

[0058] Figure 26 This is a block diagram showing the axial force calculation unit according to the ninth embodiment; and

[0059] Figure 27 It is a graph showing the relationship between the target pinion angle and the limiting axial force according to the ninth embodiment. Detailed Implementation

[0060] First embodiment

[0061] In the following description, a first embodiment will be provided in which the steering control device is applied to a steer-by-wire system.

[0062] 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. Left and right rotating wheels 16 are connected to the two ends of the rotating shaft 14 via a tie rod 15. When the rotating shaft 14 moves linearly, the rotation angle θ of the rotating wheels 16... w Change. Steering shaft 12 and pivot shaft 14 constitute the vehicle's steering mechanism.

[0063] The steering system 10 includes a reaction motor 31, a reduction gear mechanism 32, a rotation angle sensor 33, and a torque sensor 34, serving as a device 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. By applying a steering reaction force to the steering wheel 11, the driver can be given an appropriate responsiveness.

[0064] The reaction motor 31 is the source of the steering reaction force. For example, a three-phase brushless motor is used as the reaction motor 31. The reaction motor 31 (more precisely, the rotating shaft of the reaction motor 31) 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.

[0065] 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 the 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 of the steering shaft 12, i.e., 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 .

[0066] Torque sensor 34 detects steering torque T h The steering torque T h The torque is applied to the steering shaft 12 by rotating the steering wheel 11. The torque sensor 34 detects the steering torque T applied to the steering shaft 12 based on the amount of torsion of the torsion bar located in the middle of the steering shaft 12. h The torque sensor 34 is located on the side of the steering wheel 11 of the reduction gear mechanism 32 in the steering shaft 12.

[0067] The steering system 10 includes a rotary motor 41, a reduction gear mechanism 42, and a rotation angle sensor 43 as a device for generating rotational force, which is the power used to rotate the rotating wheel 16.

[0068] 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 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 in the vehicle width direction. Figure 1 The left and right directions in the middle.

[0069] 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. b The 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 because 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 so as to be axially movable and pressed against the pinion shaft 13 and the pinion shaft 44 by a support mechanism (not shown) provided in the steering system 10. Therefore, the rotating shaft 14 is supported in the housing. Another support mechanism supporting the rotating shaft 14 can be provided in the housing, without using the pinion shaft 13.

[0070] The steering system 10 includes a control unit 50. The control unit 50 controls the reaction motor 31 and the steering 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.

[0071] Control device 50 performs reaction control, causing the drive control of reaction motor 31 to generate a steering torque T. 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.

[0072] The control device 50 performs steering control, causing the rotating wheel 16 and the rotating motor 41 to rotate according to the steering state. The control device 50 bases its control on the rotation angle θ of the rotating 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. p pinion angle θp It reflects the rotation angle θ of rotating wheel 16. w The value of the value. 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 pinion angle θ 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 controlled, and the power supply to the rotating motor 41 is controlled so that the difference is canceled out.

[0073] The control device 50 will be described in detail below. For example... 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.

[0074] The reaction control unit 50a includes a steering angle calculation unit 51, a steering reaction force command value calculation unit 52, and a power 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 .

[0075] 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 the steering reaction force increases as the vehicle speed V decreases. Details of the steering reaction force command value calculation unit 52 will be described later.

[0076] The power control unit 53 supplies the steering reaction force command value T to the reaction motor 31. * The corresponding power supply. Specifically, the power 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 control unit 53 uses a current sensor 54 installed in the power path to detect the actual current I generated in the power path of the reaction motor 31. a The value of current I. a The value is the actual current supplied to the reaction motor 31. The power control unit 53 calculates the current command value and the actual current I. aThe difference between the values ​​is calculated, and the power supply to the reaction motor 31 is controlled so that the difference is canceled out. Therefore, the reaction motor 31 generates a force equal to the 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.

[0077] 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 control unit 64. The pinion angle calculation unit 61 is based on the rotation angle θ of the rotating 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. p The 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 With pinion angle θ p There is a correlation between them. This correlation can be used based on the rotation angle θ of the rotating motor 41. b To calculate the pinion angle θ p The pinion shaft 44 meshes with the rotating shaft 14. Therefore, the pinion angle θ p There is also a correlation with the offset of shaft 14. That is, the pinion angle θ p It reflects the rotation angle θ of rotating wheel 16. w The value of .

[0078] 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 * Unit 62 calculates the target pinion angle θ. p * This makes 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... w Relative to the steering angle θ s The steering angle decreases as the vehicle speed V increases. To achieve the steering angle ratio set based on 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. sThe targets are summed, and the target pinion angle θ is calculated based on the steering angle ratio. p * .

[0079] In this embodiment, the target pinion angle calculation unit 62 uses mapping Ml 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 limits the steering angle θ based on 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.

[0080] 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 controls the pinion angle θ by... p Feedback control is used to calculate the pinion angle command value T. p * This makes the actual pinion angle θ p Angle θ with the target pinion p * Consistent.

[0081] The power control unit 64 supplies the pinion angle command value T to the rotary motor 41. p * The corresponding power supply. Specifically, the power control unit 64 is based on the pinion angle command value T. p * The power control unit 64 calculates the current command value for the rotating motor 41. It uses a current sensor 65 located in the power path to detect the actual current I generated in the power path of the rotating motor 41. b The value of current I. b The value is the actual current supplied to the rotating motor 41. The power 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 so that the difference is canceled out. Therefore, the rotation of the rotary motor 41 is synchronized with the pinion angle command value T. p * The corresponding angle.

[0082] Due to the target pinion angle θ p * Relative to the steering angle θ s Based on vehicle speed V Figure 3 The curve graph shows that the mapping Ml changes accordingly, therefore, the target pinion angle θ 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 the 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.

[0083] As the steering angle ratio decreases, when the steering wheel 11 is operated, the rotation angle θ of the wheel 16 and the steering wheel 16 decreases. w and rotation angle θ w The changes are faster. Therefore, for example, when the vehicle enters a low-speed area such as a garage, a larger turning radius is obtained with a smaller steering input, thereby ensuring the vehicle's maneuverability. As the steering angle ratio increases, when the steering wheel 11 is operated, the turning angle θ of the wheel 16 and the turning wheel 16 increases. w and rotation angle θ w The changes are slower. Therefore, for example, when the vehicle performs lane changes in high-speed areas, driving stability is ensured.

[0084] The steering reaction force command value calculation unit 52 will be described in detail below. For example... Figure 4 As shown, the steering reaction force command value calculation unit 52 includes a target steering reaction force calculation unit 71, an axial force calculation unit 72, and a subtractor 73.

[0085] Target steering reaction force calculation unit 71 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 is applied in the direction opposite to the direction of steering wheel 11 and is to be generated by the reaction motor 31. The target steering reaction force calculation unit 71 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.

[0086] Axial force calculation unit 72 is based on pinion angle θp and current I of rotating motor 41. b Values ​​of the steering angle θ sThe axial force applied to the pivot 14 is calculated using the vehicle speed V, and the converted torque value (based on the steering reaction force of the axial force) T2 is calculated by converting the calculated axial force into torque. * .

[0087] Subtractor 73 uses the target turning reaction force T1 calculated from the target turning reaction force calculation unit 71. * Subtract the converted torque value T2 calculated by the axial force calculation unit 72 * To calculate the steering reaction force command value T * .

[0088] The axial force calculation unit 72 will be described in detail below. For example... Figure 4 As shown, the axial force calculation unit 72 includes a combined axial force calculation unit 81, a limited axial force calculation unit 82, a maximum value selection unit 83, and a converter 84. The combined axial force calculation unit 81 includes an angular axial force calculation unit 91, a current axial force calculation unit 92, and an axial force distribution calculation unit 93.

[0089] Angular axial force calculation unit 91 is 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 91 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 the mapping of the pinion angle θ. p A two-dimensional mapping is set as the horizontal axis and the angular axial force AF1 is set as the vertical axis, and the pinion angle θ is defined 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 [factor] increases as the vehicle speed V decreases. This increases with the pinion angle θ. p As the absolute value of the angular axial force AF1 increases, the absolute value of the angular axial force AF1 increases linearly. The angular axial force AF1 is set to be relative to the pinion angle θ. p The symbols are the same. The angular axial force AF1 is an axial force that does not reflect the road surface condition or the force acting on the rotating shaft 14.

[0090] The current axial force calculation unit 92 is based on the current I of the rotating motor 41. b The value is used to calculate the current axial force AF2 applied to the rotating shaft 14. Here, the current I of the rotating motor 41 is... b The value is due to the target pinion angle θ p * Compared to the actual pinion angle θ p The difference between them varies, while the target pinion angle θ p* Compared to the actual pinion angle θ p The difference is due to disturbances based on road conditions, such as road friction resistance, applied to the rotating wheels 16 and 16. That is, the actual road conditions applied to the rotating wheels 16 and 16 are 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. The current axial force AF2 is calculated by controlling the current I of the rotating motor 41. b The value is calculated by multiplying the gain, which is a coefficient based on the vehicle speed V. The current axial force AF2 is the axial force that reflects the road surface condition or the force acting on the shaft 14 via the rotating wheel 16.

[0091] The axial force distribution calculation unit 93 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 93 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 the distribution ratios set for them respectively.

[0092] 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 of the angular axial force AF1 is set to an increasingly larger value, and the allocation ratio of the current axial force AF2 is set to an increasingly smaller value. Conversely, as the vehicle speed V decreases, the allocation ratio of the angular axial force AF1 is set to an increasingly smaller value, and the allocation ratio of the current axial force AF2 is set to an increasingly larger value.

[0093] The axial force calculation unit 82 is based on the pinion angle θ. p The limiting axial force AF4, used to virtually limit the operating range of the steering wheel 11, is calculated. The limiting axial force AF4 is calculated based on the following consideration: when the steering wheel 11 approaches its operating range limit position, or when the shaft 14 approaches its physical operating range limit position, a rapid increase in torque generated by the reaction motor 31 in the direction opposite to the steering direction is made. The operating range limit position of the steering wheel 11 is determined, for example, by the length of the spiral cable disposed in the steering wheel 11. The physical operating range limit position of the shaft 14 is the position that physically limits the range of motion of the shaft 14 due to the occurrence of so-called "end contact," which is the contact between the rack end, which is the end of the shaft 14, and a housing (not shown). The limiting axial force AF4 is set to be relative to the pinion angle θ. p The symbols are the same. Details of the limiting axial force calculation unit 82 will be described later.

[0094] The maximum value selection unit 83 receives the combined axial force AF3 calculated by the combined axial force calculation unit 81 and the limiting axial force AF4 calculated by the limiting axial force calculation unit 82. The maximum value selection unit 83 selects the axial force with the larger absolute value from the received combined axial force AF3 and limiting axial force AF4, and sets the selected combined axial force AF3 or limiting axial force AF4 as the value used to calculate the steering reaction force command value T. * The final axial force AF5.

[0095] The converter 84 calculates the converted torque value T2 by converting the final axial force AF5 set by the maximum value selection unit 83 into torque. * Here, when the steering wheel 11 is not in a position near the limit of its operating range, or when the shaft 14 is not in a position near the limit of its physical operating range, and when the limiting axial force AF4 calculated by the limiting axial force calculation unit 82 is less than the combined axial force AF3 calculated by the combined axial force calculation unit 81, the combined axial force AF3 is set as the final axial force AF5. In this case, the converted torque value T2 obtained by converting the final axial force AF5 into torque is... * Reflected in the steering reaction force command value T * Therefore, a steering reaction force based on vehicle behavior or road conditions can be applied to the steering wheel 11. The driver can feel the steering reaction force as a response through the steering wheel 11, thereby determining the vehicle behavior or road conditions.

[0096] When the steering wheel 11 approaches the limit of its operating range or when the shaft 14 approaches the limit of its physical operating range, and when the limiting axial force AF4 calculated by the limiting axial force calculation unit 82 is greater than the combined axial force AF3 calculated by the combined axial force calculation unit 81, the limiting axial force AF4 is set as the final axial force AF5. In this case, the converted torque value T2 is obtained by converting the final axial force AF5 into torque. * Reflected in the steering reaction force command value T * Therefore, the steering reaction force increases rapidly. Consequently, it becomes difficult for the driver to maintain the steering angle θ. s The steering wheel 11 is operated in the direction where the absolute value increases. Therefore, the driver can feel the end from the steering reaction force (response) and thus realize that the steering wheel 11 has reached the limit of its virtual operating range.

[0097] The following will describe in detail the axial force calculation unit 82. For example... Figure 5As shown, the axial force calculation unit 82 includes a steering end angle calculation unit 101, a subtractor 102, and an axial force calculation unit 103.

[0098] Steering angle calculation unit 101 calculates steering angle θ based on vehicle speed V. end Steering angle θ end It is the steering angle corresponding to the extreme position of the virtual operating range of the steering wheel 11, or the pinion angle corresponding to the extreme position of the physical operating range of the pivot 14. Steering end angle θ end Based on the steering angle θ when the steering wheel 11 reaches the limit of its operating range. s The value near the pinion angle θ when the shaft 14 reaches the limit position of its operating range. p Use nearby values ​​to set.

[0099] In this embodiment, the steering angle calculation unit 101 uses the mapping M2 stored in the storage device of the control device 50 to calculate the steering angle θ. end Mapping M2 sets the vehicle speed V to the horizontal axis and the steering angle θ... end Set as a two-dimensional mapping with a vertical axis, and limit the vehicle speed V to the steering angle θ. end The relationship between them. Mapping M2 has the following properties. That is, the steering angle θ end The absolute value of increases as the vehicle speed V increases.

[0100] Subtractor 102 uses the steering angle θ calculated by steering angle calculation unit 101. end Subtract the steering angle θ calculated by the steering angle calculation unit 51 s To calculate the angle difference Δθ1. Additionally, subtractor 102 can calculate the angle difference Δθ1 from the turning angle θ. end Subtract the pinion angle θ calculated by pinion angle calculation unit 61 p To calculate the angle difference Δθ1.

[0101] The axial force calculation unit 103 calculates the limiting axial force AF4 based on the angle difference Δθ1 calculated by the subtractor 102. The axial force calculation unit 103 uses a mapping M3 stored in the storage device of the control device 50 to calculate the limiting axial force AF4. Mapping M3 is a two-dimensional mapping that sets the angle difference Δθ1 as the horizontal axis and the limiting axial force AF4 as the vertical axis, and defines the relationship between the angle difference Δθ1 and the limiting axial force AF4. Mapping M3 has the following characteristic: when the absolute value of the angle difference Δθ1 is equal to or less than the end set relative to "0", a threshold θ is determined. thAt this time, a limiting axial force AF4 is generated, and the limiting axial force AF4 increases rapidly in the direction in which its absolute value increases as the absolute value of the angle difference Δθ1 decreases to "0". When the absolute value of the angle difference Δθ1 is greater than the end-determined threshold θ th At this time, the value of the limiting axial force AF4 remains "0". Furthermore, the limiting axial force AF4 is set to be related to the pinion angle θ. p The symbols are the same as the symbols.

[0102] This configuration adjusts the virtual operating range of the steering wheel 11 to a more suitable range based on the vehicle speed V. Here, the steering angle θ, which is the limit value of the virtual operating range of the steering wheel 11, is used as the adjustment factor. end The virtual operating range varies depending on the vehicle speed V, thus raising concerns as will be described below. Specifically, when the vehicle decelerates or accelerates while the steering wheel 11 is already at the limit of its virtual operating range, the limit of the virtual operating range changes with the vehicle speed V. Therefore, there is a concern that undesirable steering behavior may occur.

[0103] like Figure 10 As shown in the left portion, for example, when the vehicle decelerates while the steering wheel 11 is at the limit of its virtual operating range, the operating range of the steering wheel 11 narrows as the vehicle speed V decreases. It is conceivable that, due to the steering reaction force generated when the operating range narrows, the steering wheel 11 rotates to be pushed back in the opposite direction to the current steering direction. Because the steering wheel 11 is unintentionally pushed back, the driver may feel discomfort (a feeling of resistance).

[0104] like Figure 10 As shown in the right part, when the vehicle is accelerated with the steering wheel 11 already at its virtual operating range limit, the operating range of the steering wheel 11 widens with increasing vehicle speed V. That is, since the current limit of the operating range is no longer the limit, the steering wheel 11 can be turned further in the current steering direction. The driver does not feel a steering reaction force via the steering wheel 11 and may therefore experience a so-called steering error.

[0105] Therefore, in this embodiment, the following configuration is used as the axial force calculation unit 82 to suppress changes in steering behavior that are not desired by the driver. Figure 6 As shown, the axial force calculation unit 82 includes a correction processing unit 104 in addition to the steering end angle calculation unit 101, the subtractor 102 and the axial force calculation unit 103.

[0106] The correction processing unit 104 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 104 includes a differentiator (S) 111, an end determination unit 112, and a corrected vehicle speed calculation unit 113.

[0107] Differentiator 111 processes the steering angle θ calculated by steering angle calculation unit 51. s The steering angular velocity ω is calculated by differentiation. The end-point determination unit 112 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 angle θ calculated by the steering angle calculation unit 101 end And based on vehicle speed V and steering angle θ s and steering angle θ end The end-of-range determination unit 112 determines whether the operating position of the steering wheel 11 has reached or is near the limit of its virtual operating range. The end-of-range determination unit 112 sets the value of flag F0 to the end-of-range determination result, which indicates whether the operating position of the steering wheel 11 has reached or is near the limit of its operating range. Details of the end-of-range determination unit 112 will be described later.

[0108] The vehicle speed calculation unit 113 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 steering angular velocity ω calculated by the differentiator 111 and the value of the flag F0 set by the end-determining unit 112. The vehicle speed correction calculation unit 113 is based on the vehicle speed V and the steering angle θ. s The values ​​of the steering angular velocity ω and the indicator F0 are used to calculate the corrected vehicle speed V by correcting the value of the vehicle speed V detected by the vehicle speed sensor 501. c Details regarding the calibration of the vehicle speed calculation unit 113 will be described later.

[0109] Steering angle calculation unit 101 receives the corrected vehicle speed V as the vehicle speed V corrected by the corrected vehicle speed calculation unit 113. c And based on the received corrected vehicle speed V c To calculate the steering angle θ end .

[0110] The configuration of the end-point determination unit 112 will be described in detail below. For example... Figure 7 As shown, the end determination unit 112 includes a subtractor 112A, an absolute value calculation unit (ABS) 112B, and two determination units 112C and 112D.

[0111] Subtractor 112A receives the steering angle θ calculated by steering angle calculation unit 51. s and the steering angle θ calculated by the steering angle calculation unit 101 end Subtractor 112A operates by measuring the turning angle θ. s Subtract the steering angle θ end To calculate the angle difference Δθ2.

[0112] The absolute value calculation unit 112B calculates the absolute value of the angle difference Δθ2 calculated by the subtractor 112A. The determination unit 112C receives the absolute value of the angle difference Δθ2 calculated by the absolute value calculation unit 112B and the angle difference threshold Δθ stored in the vehicle's storage device. th Angular difference threshold Δθ th The settings are based on the following considerations: determining whether the operating position of the steering wheel 11 has reached the vicinity of the limit position of the virtual operating range. When the absolute value of the angle difference Δθ2 is less than the angle difference threshold Δθ... th When the steering wheel 11 is near its virtual operating range, the determining unit 112C determines that the operating position of the steering wheel 11 has reached the vicinity of the limit position and sets the value of the flag F1 to "1". When the absolute value of the angle difference Δθ2 is equal to or greater than the angle difference threshold Δθ... th When the steering wheel 11 is in operation, the determining unit 112C determines that the operating position of the steering wheel 11 has not yet reached the limit position of the virtual operating range, and sets the value of the flag F1 to "0".

[0113] The determining unit 112D receives the value of the flag F1 set by the determining unit 112C and the vehicle speed V detected by the vehicle speed sensor 501. When the value of the flag F1 is "0" or when the vehicle speed V is equal to or higher than the vehicle speed threshold, the determining unit 112D sets the value of the flag F0, which is the end determination result, to "0". For example, when the value of the flag F1 is "1" and the vehicle speed V is lower than the vehicle speed threshold, the determining unit 112D sets the value of the flag F0, which is the end determination result, to "1".

[0114] The end-point determination unit 112 can determine whether the operating position of the steering wheel 11 has reached the vicinity of the limit position of the virtual operating range without using the vehicle speed V. In this case, the end-point determination unit 112 can be configured without the determination unit 112D. The flag F1 set by the determination unit 112C is the flag F0, which is the end-point determination result.

[0115] The configuration of the vehicle speed calculation unit 113 will be described in detail below. For example... Figure 8As shown, the vehicle speed correction calculation unit 113 includes a determination unit 113A, a previous value storage unit 113B, a switch 113C, an upper limit value calculation unit 113D, a lower limit value calculation unit 113E, a previous value storage unit 113F, a determination unit 113G, and a protection processing unit 113H.

[0116] The determining unit 113A receives the value of flag F0 set by the end determining unit 112, and sets the value of flag F3 according to the received value of flag F0. Flag F3 indicates the value used to calculate the target pinion angle θ. p * Whether the vehicle speed V will be fixed. When the value of the flag F0 is "1", that is, when the steering wheel 11 is held at a constant steering angle θ. s At that time, the unit 113A determines the angle θ of the target pinion. p * The vehicle speed V will be fixed, and the value of sign F3 will be 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 unit 113A determines the angle θ of the target pinion. p * The vehicle speed V will not be fixed, and the value of flag F3 will be set to "0".

[0117] Previous value storage unit 113B receives the corrected vehicle speed V calculated by the protection processing unit 113H, which will be described later. c And store the received corrected vehicle speed V c The protection processing unit 113H calculates and corrects the vehicle speed V at predetermined operating cycle intervals. c And whenever the protection processing unit 113H calculates the corrected vehicle speed V c At that time, update the corrected vehicle speed V stored in the previous value storage unit 113B. c That is, the corrected vehicle speed V stored in the previous value storage unit 113B. c The corrected vehicle speed V is calculated by the protection processing unit 113H. c The previous value of the current value (corrected vehicle speed V one operating cycle prior) c ).

[0118] Switch 113C receives the vehicle speed V detected by vehicle speed sensor 501 and the corrected vehicle speed V stored in previous value storage unit 113B. c Previous value V cn-1As data input, switch 113C receives the value of flag F3 set by determination unit 113A as control input. Switch 113C selects the vehicle speed V detected by vehicle speed sensor 501 and the corrected vehicle speed V stored in previous value storage unit 113B 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 113C selects the vehicle speed V detected by vehicle speed sensor 501 as the temporary vehicle speed value V. temp When the value of indicator F3 is "1" (more precisely, when the value of indicator F3 is not "0"), switch 113C selects to correct the vehicle speed V. c Previous value V cn-1 As a temporary vehicle speed value V temp .

[0119] When the steering wheel 11 is kept at a constant steering angle θ s When 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 113B is... c Previous value V cn-1 The temporary vehicle speed value V is usually selected. temp .

[0120] Switch 113C can receive the value of flag F0 set by end determination unit 112 as a control input. When this configuration is used, the vehicle speed calculation unit 113 can be used with the determination unit 113A omitted.

[0121] The upper limit calculation unit 113D 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 differentiator 111, and based on the received vehicle speed V and steering angle θ s The temporary vehicle speed value V is calculated using the steering angular velocity ω. temp The upper limit of the change V in each operating cycle UL Details of the upper limit calculation unit 113D will be described later.

[0122] The lower limit calculation unit 113E 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 differentiator 111, and based on the received vehicle speed V and steering angle θ s The temporary vehicle speed value V is calculated using the steering angular velocity ω.temp The lower limit of the change in each operating cycle, V LL Details of the lower limit calculation unit 113E will be described later.

[0123] The previous value storage unit 113F receives the value of flag F4 set by the determination unit 113G (described later) and stores the received value of flag F4. The determination unit 113G 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 113F whenever the determination unit 113G sets the value of flag F4. That is, the value of flag F4 stored in the previous value storage unit 113F is the previous value of flag F4 (the value of flag F4 one operating cycle ago) that is the current value set by the determination unit 113G.

[0124] Unit 113G determines whether to limit the corrected vehicle speed V. c The value of flag F4, which indicates the determination result, is set for each operation cycle. Determination unit 113G receives the value of flag F3 set by determination unit 113A and the corrected vehicle speed V stored in previous value storage unit 113B. c Previous value V cn-1 The temporary vehicle speed value V selected by switch 113C temp and the previous value F4 of the flag F4 stored in the previous value storage unit 113F. n-1 The determination unit 113G determines 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:

[0125] When the value of flag F3 set by determining unit 113A 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 113G sets the value of the flag F4 to "1".

[0126] Subsequently, when the following expression (A1) is satisfied, the determining unit 113G sets the value of flag F4 to "0". When the following expression (A1) is not satisfied, the determining unit 113G keeps the value of flag F4 set to "1".

[0127] |V temp -V c |≤V th …(A1)

[0128] Here, "V" temp "V" is the temporary vehicle speed value selected by switch 113C, and "V" c "The corrected vehicle speed is calculated by the protection processing unit 113H." 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 reference value that is small enough? Vehicle speed threshold V th The settings are based on the following considerations: when the steering state of the steering wheel 11 changes from a holding steering state to a non-holding steering state, the target pinion angle θ is suppressed based on the difference between the fixed vehicle speed and the actual vehicle speed. p * The sudden change.

[0129] In addition, when the value of flag F3 has not changed from "1" to "0", that is, when the value of flag F3 is "0", and when the value of flag F3 has changed from "0" to "1", the determining unit 113G sets the value of flag F4 to "0".

[0130] Based on the value of flag F4 set by determination unit 113G, protection processing unit 113H causes the temporary vehicle speed value V selected by switch 113C to be adjusted. temp The restriction processing function switches between active and inactive. When the value of flag F4 is set to "1", that is, when the steering wheel 11's holding steering state is released, the protection processing unit 113H enables the temporary vehicle speed value V to be restricted. temp The limitation processing function is effective. The protection processing unit 113H 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 operation cycle. The specific execution of this operation is as follows.

[0131] 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 be limited to the upper limit value V. UL The change corresponds to the 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. LLIt has been changed to be restricted to the lower limit value V. LL The change corresponds to the 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.

[0132] When the value of flag F4 is set to "0", the protection processing unit 113H 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 113C is invalid. temp Calculated as the corrected vehicle speed V c Without making any changes.

[0133] The upper limit calculation unit 113D will be described in detail below. For example... Figure 9 As shown, the upper limit calculation unit 113D includes two limit value calculation units 121A and 121B, two gain calculation units 122A and 122B, two multipliers 123A and 123B, and a selection processing unit 124.

[0134] Limit value calculation unit 121A calculates the limit value V based on the steering angular velocity ω calculated by differentiator 111. a The limit value calculation unit 121A 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 limit value V... a The value increases. Additionally, mapping M4 is set based on the following consideration: as the absolute value of the steering angular velocity ω increases, the value used to calculate the target pinion angle θ... p * The vehicle speed, or the value of the steering angle ratio, returns to its true value more quickly without undergoing any correction process for the vehicle speed.

[0135] The gain calculation unit 122A calculates the gain G based on the vehicle speed V detected by the vehicle speed sensor 501. a The gain calculation unit 122A 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 gain G. a A two-dimensional mapping of the relationship between them, and with the following properties. That is, when the vehicle speed V has a value in the extremely low speed region close to "0", the gain G...a The value of increases rapidly with increasing vehicle speed V. When vehicle speed V exceeds its value in the extremely low speed region, the gain G... a The value increases slowly as the vehicle speed V increases.

[0136] Multiplier 123A multiplies the limit value V calculated by limit value calculation unit 121A. a Multiply by the gain G calculated by the gain calculation unit 122A a To calculate the pre-limit value V A .

[0137] Limit value calculation unit 121B is based on the steering angle θ calculated by steering angle calculation unit 51. s To calculate the limit value V b The limit value calculation unit 121B uses the mapping M6 stored in the storage device of the control device 50 to calculate the limit value V. b Mapping M6 defines the steering angle θ. s The absolute value and limit value V b A two-dimensional mapping of the relationship between them, and it has the following properties. That is, as the turning angle θ... s As the absolute value increases, the limit value V b The value decreases slowly.

[0138] The gain calculation unit 122B calculates the gain G based on the vehicle speed V detected by the vehicle speed sensor 501. b The gain calculation unit 122B 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: As the vehicle speed V increases relative to "0", the gain G... b The value increases slowly. Mapping M7 is set based on the following perspective: as the vehicle speed V increases, the value used to calculate the target pinion angle θ... p * The vehicle speed returns to its true value more quickly with the steering angle ratio, without undergoing any correction process for the vehicle speed.

[0139] Multiplier 123B multiplies the limit value V calculated by limit value calculation unit 121B. b Multiply by the gain G calculated by the gain calculation unit 122B b To calculate the pre-limit value V B .

[0140] The selection processing unit 124 selects the pre-limit value V calculated by the multiplier 123A. AThe pre-limit value V calculated by multiplier 123B B The upper limit value V is calculated by comparing the two. UL Current limit V A Equal to or less than the pre-limit value V B At that time, the selection processing unit 124 selects the preceding limit value V. B As the upper limit value V UL As expressed by the following expression (A2). In this case, the target pinion angle θ is used to calculate the target pinion angle unless the vehicle speed V is "0". p * The vehicle speed, or the steering angle ratio, slowly returns to its true value over time without undergoing any correction process for vehicle speed.

[0141] V A ≤V B →V UL =V B …(A2)

[0142] Current limit V A Greater than the pre-limit value V B At that time, the selection processing unit 124 selects the preceding limit value V. A As the upper limit value V UL As expressed by the following expression (A3). In this case, the target pinion angle θ is used to calculate the target pinion angle unless the vehicle speed V is "0". p * The vehicle speed, or the steering angle ratio, gradually returns to its true value over time without any correction to the vehicle speed, based on the steering angle velocity ω.

[0143] V A >V B →V UL =V A …(A3)

[0144] The lower limit calculation unit 113E will now be described in detail. The lower limit calculation unit 113E has the same configuration as the upper limit calculation unit 113D. That is, as... Figure 9 As described in parentheses, the lower limit calculation unit 113E includes two limit calculation units 131A and 131B, two gain calculation units 132A and 132B, two multipliers 133A and 133B, and a selection processing unit 134.

[0145] Limit value calculation unit 131A calculates the limit value V based on the steering angular velocity ω calculated by differentiator 111. a The gain calculation unit 132A calculates the gain G based on the vehicle speed V detected by the vehicle speed sensor 501. aThe multiplier 133A uses the limit value V calculated by the limit value calculation unit 131A. a The leading limit value V is calculated by multiplying it by the gain Ga calculated by the gain calculation unit 132A. A .

[0146] Limit value calculation unit 131B 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 132B calculates the gain G based on the vehicle speed V detected by the vehicle speed sensor 501. b The multiplier 133B uses the limit value V calculated by the limit value calculation unit 131B. b Multiply by the gain G calculated by the gain calculation unit 132B b To calculate the pre-limit value V B .

[0147] Current limit V A Equal to or less than the pre-limit value V B At that time, the selection processing unit 134 selects the preceding limit value V. B As the lower limit value V LL As expressed by the following expression (A4). Current limit V A Greater than the pre-limit value V B At that time, the selection processing unit 134 selects the preceding limit value V. A As the lower limit value V LL As expressed by the following expression (A5).

[0148] V A ≤V B →V LL =V B …(A4)

[0149] V A >V B →V UL =V A …(A5)

[0150] The operation in the first embodiment will now be described.

[0151] When the steering wheel 11 has reached a position near the limit of its operating range, the value of flag F0 is set to "1" by the end determination unit 112, and the value of flag F3 is set to "1" by the determination unit 113A. Therefore, during the period when the steering wheel 11 is held at or near the limit of its operating range, the corrected vehicle speed V stored in the previous value storage unit 113B is... c Previous value V cn-1The temporary vehicle speed value V is usually selected. temp When the steering wheel 11 has reached a position near the limit of its operating range, the value of flag F4 is set to "1" by the determination unit 113G. At this time, the restriction processing function of the protection processing unit 113H remains invalid.

[0152] Therefore, the corrected vehicle speed V stored in the previous value storage unit 113B c Previous value V cn-1 It is usually calculated as the corrected vehicle speed V c That is, regardless of the actual value of the vehicle speed V detected by the vehicle speed sensor 501, it is used to calculate the steering angle θ. end The final vehicle speed correction vehicle speed V c The value remains unchanged. Therefore, when the steering wheel 11 has reached a position near the limit of its operating range, even if the vehicle begins to decelerate or accelerate, the steering angle θ remains unchanged. end The value does not change.

[0153] That is, even when the vehicle decelerates while the steering wheel 11 is at its virtual operating range limit, the operating range of the steering wheel 11 does not narrow as the vehicle speed V decreases. Therefore, the steering wheel 11 does not rotate in a way that pushes it back in the opposite direction of the current steering direction. Therefore, the driver does not feel discomfort (a feeling of resistance). Even when the vehicle accelerates while the steering wheel 11 is at its virtual operating range limit, the operating range of the steering wheel 11 does not widen as the vehicle speed V increases. That is, since the current limit of the operating range is maintained, the driver does not feel any so-called steering error.

[0154] Then, when the value of flag F0, which is the end determination result, is set to "0" because the operating position of steering wheel 11 has moved away from the position near the limit of its operating range due to the steering of steering wheel 11, the value of flag F3 is set to "0" by determination unit 113A. Therefore, after the operating position of steering wheel 11 has moved away from the position near the limit of its operating range, the vehicle speed V detected by vehicle speed sensor 501 is selected as the temporary vehicle speed value V by switch 113C. temp When the value of flag F3 changes from "1" to "0", the value of flag F4 is set to "1" by the determining unit 113G. Therefore, the temporary vehicle speed value V in the protection processing unit 113H is adjusted. temp The restriction processing function is effective. Therefore, the temporary vehicle speed value V temp Or it can be used to calculate the steering angle θ. end Corrected vehicle speed V cThe variation in each operating cycle is limited to an upper limit value V. UL Or lower limit value V LL .

[0155] It is conceivable that the temporary vehicle speed value V is used just before the steering wheel 11 reaches its limit position, which is far from the limit of its operating range. temp The vehicle speed becomes different from the vehicle speed V immediately following the point where the steering wheel 11's operating position has moved far from its operating range's limit. In this case, the steering angle θ is based on the vehicle speed before the steering wheel 11's operating position is about to move far from its operating range's limit. end The steering angle θ becomes different from the vehicle speed based on the position immediately following the operating position of the steering wheel 11, which has moved far away from the limit position of its operating range. end Therefore, when using a vehicle speed V immediately following a position where the steering wheel 11 has moved far from its limit position of operation, there exists a steering angle θ. end Concerns about rapid changes.

[0156] In this respect, in this embodiment, when the operating position of the steering wheel 11 has moved away from the extreme position of its operating range, 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 for calculating the steering angle. end The final vehicle speed correction vehicle speed V c Rapid changes in the value of V. Correcting vehicle speed V. c The values ​​depend on the vehicle's steering state (in this article, steering angular velocity ω and steering angle θ). s The steering angle θ can be slowly changed over time by the vehicle speed sensor 501, either due to the vehicle's driving state (vehicle speed V in this article) or its driving condition. Therefore, the steering angle θ can be suppressed. end Rapid changes.

[0157] When the temporary vehicle speed value V temp (In this article, the vehicle speed V is detected by the vehicle speed sensor 501) and is used to calculate the steering angle θ. end 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 value of flag F4 is set to "0" by the determination unit 113G. Therefore, the temporary vehicle speed value V in the protection processing unit 113H is set. tempThe limiting processing function is invalid. Therefore, the vehicle speed V detected by the vehicle speed sensor 501 is used to correct the vehicle speed V. c To calculate the steering angle θ end Without making any changes, that is, calculating the steering angle θ corresponding to the actual vehicle speed V. end A more suitable steering angle θ end .

[0158] Therefore, according to the first embodiment, the following advantages can be obtained. When the operating position of the steering wheel 11 has reached a position near the limit of its virtual operating range, it serves as a reference for calculating the steering angle θ. end The final vehicle speed correction vehicle speed V c The vehicle speed is fixed before the steering wheel 11 reaches its limit position within its operating range. That is, regardless of the actual value of the vehicle speed V, the steering angle θ... end The steering angle θ is maintained at a value corresponding to the vehicle speed V when the steering wheel 11 is positioned near the limit of its operating range. Therefore, even when the vehicle speed V changes while the steering wheel 11 is positioned near the limit of its operating range, the steering angle θ remains constant. end It does not change with the vehicle speed V.

[0159] That is, when the vehicle decelerates while the steering wheel 11 is near the limit of its virtual operating range, the operating range of the steering wheel 11 does not narrow as the vehicle speed V decreases. Therefore, the steering wheel 11 does not rotate in a way that pushes it back in the opposite direction of the current steering direction. Thus, the driver does not experience discomfort, such as a feeling of resistance. When the vehicle accelerates while the steering wheel 11 is near the limit of its operating range, the operating range of the steering wheel 11 does not widen as the vehicle speed V increases. That is, since the current limit of the operating range is maintained, the driver does not experience a so-called steering error. In this way, even when the vehicle speed V changes while the steering wheel 11 is near the limit of its virtual operating range, changes in the steering feel that are not desired by the driver can be suppressed.

[0160] When the steering wheel 11 has moved far from the limit position of its virtual operating range, the fixed state of the vehicle speed value is released, and the actual vehicle speed V detected by the vehicle speed sensor 501 is used to calculate the steering angle θ. end At this point, the angle θ used to calculate the steering angle is... end The final vehicle speed correction vehicle speed V cThe variation in each operating cycle is limited to an upper limit value V by the protection processing unit 113H. UL and lower limit value V LL .

[0161] Therefore, even if the value of the vehicle speed fixed before the steering wheel 11's operating position is about to move away from the limit position of its virtual operating range becomes different from the value of the vehicle speed V immediately after the steering wheel 11's operating position has already moved away from the limit position of its virtual operating range, 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 suppresses the steering angle θ. end Rapid changes.

[0162] In this embodiment, when the operating position of the steering wheel 11 has moved far away from the extreme position of its virtual operating range, the vehicle speed V is corrected. c The variation in each operating cycle is limited to an upper limit value V. UL With lower limit value V LL The so-called time-varying protection processing for values ​​between these parameters can be replaced by offset processing. For example, when the operating position of the steering wheel 11 has moved away from the limit position of its virtual operating range due to the steering of the steering wheel 11, the vehicle speed V is corrected. c The difference between the current value and the previous value is set as the correction vehicle speed V. c The offset value, and this offset value slowly changes to "0" over time.

[0163] Second Implementation Method

[0164] The steering control device according to the second embodiment will now be described. This embodiment basically employs the same... Figures 1 to 9 The configuration is the same as that in 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.

[0165] like Figure 11 As shown, the control device 50 includes a divider 141, an adder 142, and a differentiator 143. The divider 141 receives the steering torque T detected by the torque sensor 34. h The divider 141 uses the steering torque T h The torsion angle θ of the torsion bar, which is a component of the torque sensor 34, is calculated by dividing by the torsional stiffness coefficient of the torsion bar. tb .

[0166] Adder 142 measures the torsion angle θ of the torsion bar calculated by divider 141. 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 .

[0167] Differentiator 143 uses the estimated steering angle θ calculated by adder 142. es To calculate the estimated steering angular velocity ω by performing differentiation es For example, the axial force calculation unit 82 uses the estimated steering angle θ. es The steering angle θ calculated by the steering angle calculation unit 51 is replaced. s Using the estimated steering angular velocity ω es The steering angular velocity ω calculated by the differentiator 111 is used to perform the process of correcting the vehicle speed V and calculating the steering angle θ. end The processing.

[0168] 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 operating position of the steering wheel 11 has moved away from the extreme position of its virtual operating range, the state in which the vehicle speed value is fixed is released. At this time, the value used to calculate the steering angle θ is... end The final vehicle speed correction vehicle speed V c The value of θ changes slowly over time according to the steering state, becoming the value of the vehicle speed V detected by the vehicle speed sensor 501. Here, in the first embodiment, the steering angle θ s Steering angular velocity ω is used as a state variable to indicate the steering state, but in this embodiment, a steering torque-based variable T is used. h Calculated estimated steering angle θ es And estimate the steering angular velocity ω es Therefore, it can improve the accuracy when used to calculate the steering angle θ. end The final vehicle speed correction vehicle speed V c The responsiveness of the value returning to the vehicle speed V detected by the vehicle speed sensor 501 is as follows. That is, even if the steering wheel 11 has a small steering amount, the steering amount is immediately detected as the steering torque T that turns the steering wheel 11. h The change in the steering angle θ. s Based on the rotation angle θ of the reaction motor 31 a To calculate the point in time when the steering wheel 11 has been turned and the amount of steering of the steering wheel 11, the rotation angle θ of the reaction motor 31 is reflected in the reaction motor. a The value is then calculated as the steering angle θ. sThere 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.

[0169] Third embodiment

[0170] 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 steering angle θ. end The method described herein can be applied to the second embodiment.

[0171] like Figure 12 As shown, the limiting axial force calculation unit 82 includes a speed increase ratio calculation unit 151 and a divider 152. The speed increase ratio calculation unit 151 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 151 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.

[0172] The divider 152 uses the pinion angle θ calculated by the pinion angle calculation unit 61. p The turning angle θ is calculated by dividing by the growth rate ratio ν calculated by the growth rate ratio calculation unit 151. end .

[0173] Here, when the speed increase ratio ν varies with the vehicle speed V, similar to the first embodiment, the following concerns arise. That is, for example, it is conceivable that the vehicle decelerates or accelerates when the steering wheel 11 is in a position near its operating limit, having already moved far from the limit of its operating range. In this case, since the speed increase ratio ν changes with the vehicle speed V, the steering angle θ... end It varies depending on the vehicle speed V. Therefore, similar to the first embodiment, there is a concern about changes in steering behavior that are not desired by the driver.

[0174] Therefore, in this embodiment, the following configuration is used as the limiting axial force calculation unit 82. For example... Figure 12 As shown, the axial force limiting calculation unit 82 includes a correction processing unit 160. The correction processing unit 160 corrects the speed increase ratio ν detected by the speed increase ratio calculation unit 151 based on the steering state of the steering wheel 11.

[0175] The correction processing unit 160 includes a differentiator 161, an end determination unit 162, a determination unit 163, two previous value storage units 164 and 165, an upper limit value calculation unit 166, a lower limit value calculation unit 167, a determination unit 168, and a protection processing unit 169.

[0176] Differentiator 161 processes the steering angle θ calculated by steering angle calculation unit 51. s The steering angular velocity ω is calculated by differentiation. The end-point determination unit 162 has... Figure 6 and Figure 7 The end-point determination unit 162 shown in the first embodiment has the same function. The end-point determination unit 162 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 and the steering angle θ calculated by the steering angle calculation unit 101 end The end-point determination unit 162 determines whether the operating position of the steering wheel 11 has reached the vicinity of the limit position of its virtual operating range. When it is determined that the operating position of the steering wheel 11 has reached the vicinity of the limit position of its virtual operating range, the end-point determination unit 162 sets the value of the flag F0 to "1". When it is determined that the operating position of the steering wheel 11 has not yet reached the vicinity of the limit position of its virtual operating range, the end-point determination unit 162 sets the value of the flag F0 to "0".

[0177] Determining unit 163 has the same as Figure 8 The determination unit 163 performs the same function as the determination unit 113A according to the first embodiment. Here, the determination unit 163 receives the value of the flag F0 set by the end determination unit 162, and sets the value of the flag F5, which indicates whether the change in the speed increase ratio ν with the change in vehicle speed V will be limited, 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 holding steering state, the determination unit 163 determines that the change in the speed increase ratio ν with the change in vehicle speed V will be 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 holding steering state, the determination unit 163 determines that the change in the speed increase ratio ν with the change in vehicle speed V will not be limited, and sets the value of the flag F5 to "0".

[0178] The previous value storage unit 164 receives the value of the flag F6 set by the determination unit 168 and stores the received value of the flag F6. The value of the flag F6 stored in the previous value storage unit 164 is the previous value of the current value of the flag F6 set by the determination unit 168.

[0179] Previous value storage unit 165 receives the correction speed ratio ν calculated by protection processing unit 169, which will be described later. cAnd the stored correction speedup is greater than ν c The correction speed ratio ν stored in the previous value storage unit 165 c The correction speed ratio ν is calculated by the protection processing unit 169. c The previous value of the current value.

[0180] The upper limit calculation unit 166 has the same as Figure 8 The upper limit calculation unit 166 has the same function as the upper limit calculation unit 113D according to the first embodiment. Here, the upper limit calculation unit 166 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 differentiator 111, and based on the received vehicle speed V and steering angle θ s The upper limit of the change in the speed-up ratio ν per operating cycle is calculated using the steering angular velocity ω. UL .

[0181] The lower limit calculation unit 167 has the same as Figure 8 The lower limit calculation unit 167 shown in the first embodiment has the same function. Here, the lower limit calculation unit 167 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 differentiator 111, and based on the received vehicle speed V and steering angle θ s The lower limit of the change in the growth ratio ν per operating cycle is calculated using the steering angular velocity ω. LL .

[0182] Determining unit 168 has the same as Figure 8 The determination unit 168 has the same function as the determination unit 113G according to the first embodiment. Here, the determination unit 168 determines whether the change of the growth rate ratio ν in each operating cycle will be restricted, and sets the value of the flag F6 indicating its determination result. The determination unit 168 receives the value of the flag F5 set by the determination unit 163 and the corrected growth rate ratio ν stored in the previous value storage unit 165. c Previous value ν cn-1 The growth rate ratio ν calculated by the growth rate calculation unit 151 and the previous value F6 of the flag F6 stored in the previous value storage unit 164. n-1 The determination unit 168 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. n-1 To set the value of flag F6, follow these steps:

[0183] When the value of flag F5 is kept at "0" and the operating position of steering wheel 11 has not yet reached the vicinity of the limit position of its operating range, the determining unit 168 sets the value of flag F6 to "0". When the value of flag F5 changes from "0" to "1", that is, when the operating position of steering wheel 11 has reached the vicinity of the limit position of its operating range, the determining unit 168 sets the value of flag F6 to "1". When the value of flag F5 changes from "1" to "0", that is, when the state of the operating position of steering wheel 11 having reached the vicinity of the limit position of its virtual operating range changes to the state of the operating position of steering wheel 11 having moved away from the vicinity of the limit position of its virtual operating range, the determining unit 168 sets the value of flag F6 to "1".

[0184] When the following expression (A5) is satisfied after the value of flag F5 has changed from "1" to "0", the determining unit 168 sets the value of flag F6 to "0". When the following expression (A5) is not satisfied, the determining unit 168 keeps the value of flag F6 set to "1".

[0185] |ν-ν c |≤ν th …(A5)

[0186] Here, "ν" is the growth rate calculated by the growth rate calculation unit 151, and "ν" c "This is the correction speed-up ratio calculated by the protection processing unit 169." th "This is the growth rate threshold and is used to determine the growth rate ν calculated by the growth rate calculation unit 151 and the corrected growth rate ν." c Is the difference between the reference values ​​small enough? (growth rate ratio ν) th The setting is based on the following consideration: when the operating position of the steering wheel 11 has moved far away from the extreme position of its virtual operating range, the correction speed-up ratio ν calculated by the protection processing unit 169 is used. c The difference between the actual growth rate ratio ν calculated by the growth rate ratio calculation unit 151 and the actual growth rate ratio ν is used to suppress the steering angle θ. end Rapid changes.

[0187] Protection processing unit 169 has the same as Figure 8 The protection processing unit 169 has the same function as the protection processing unit 113H according to the first embodiment. Here, the protection processing unit 169 switches the function of limiting the growth rate ν calculated by the growth rate calculation unit 151 between active and inactive based on the value of the flag F6 set by the determination unit 168. When the value of the flag F6 is "1", the protection processing unit 169 enables the function of limiting the growth rate ν. The protection processing unit 169 uses the upper limit value ν calculated by the upper limit value calculation unit 166.UL and the lower limit value ν calculated by the lower limit calculation unit 167 LL This limits the change in the growth rate ratio ν for each operating cycle. The specific operation is as follows.

[0188] 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 The value is limited to an upper limit ν. UL The rate of change of ν is calculated as the corrected rate of change 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 The value is restricted to the lower limit ν. LL The rate of change of ν is calculated as the corrected rate of change 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.

[0189] When the value of flag F6 is set to "0", the protection processing unit 169 disables the limiting function for the growth rate ratio ν. That is, the growth rate ratio ν calculated by the growth rate calculation unit 151 is calculated as the corrected growth rate ratio ν. c Without making any changes.

[0190] The operation of the third embodiment will now be described. When the steering wheel 11 has reached a position near the limit of its virtual operating range, the value of flag F5 is set to "1" by the determination unit 163. When flag F5 changes from "0" to "1", the value of flag F6 is set to "1" by the determination unit 168. Therefore, the limiting processing function for the speed ratio ν in the protection processing unit 169 is activated. 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 166. UL Or the lower limit value ν calculated by the lower limit calculation unit 167 LL Here, for example, it can be assumed that the value of the growth ratio ν calculated by the growth ratio calculation unit 151 changes rapidly with the change in vehicle speed V caused by the vehicle's deceleration or acceleration, and that the growth ratio ν changes more rapidly in each operating cycle 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 steering angle θ end The final growth rate ratio and the corrected growth rate ratio ν cThe change in each operating cycle does not exceed the upper limit value ν UL Therefore, the corrected speed increase ratio ν caused by changes in vehicle speed V can be suppressed. c The value or steering angle θ end The value changes rapidly.

[0191] Therefore, as Figure 10 As shown in the left portion, when the vehicle begins to decelerate while the steering wheel 11 is in a position near the limit of its virtual operating range, the operating range of the steering wheel 11 narrows slowly over time, rather than narrowing rapidly due to the decrease in vehicle speed V. Therefore, it prevents the steering wheel 11 from rotating in a direction opposite to the current steering direction. Thus, driver discomfort, such as a feeling of resistance, can be suppressed. Figure 10 As shown in the right part, when the vehicle begins to accelerate while the steering wheel 11 is already near the limit of its virtual operating range, the operating range of the steering wheel 11 widens slowly over time, rather than rapidly due to the increase in vehicle speed V. Therefore, the driver's perceived steering error can be suppressed. In this way, even when the vehicle speed V changes while the steering wheel 11 is near the limit of its virtual operating range, changes in the driver's undesirable steering feel can be suppressed.

[0192] Then, when the operating position of the steering wheel 11 has moved far away from the limit position of its virtual operating range, the value of flag F5 is set to "0" by the determination unit 163. When the value of flag F5 changes from "1" to "0", the determination unit 168 keeps the value of flag F6 set to "1". Therefore, the limiting processing function for the speed ratio ν in the protection processing unit 169 remains effective. Therefore, as used to calculate the target pinion angle θ p * The final growth rate ratio and the corrected 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 .

[0193] Here, it is conceivable that the rate of increase ν of the vehicle speed V before the steering wheel 11's operating position is about to move away from the limit position of its virtual operating range becomes different from the rate of increase ν of the vehicle speed V immediately after the steering wheel 11's operating position has already moved away from the limit position of its virtual operating range. In this case, the steering angle θ based on the rate of increase ν before the steering wheel 11's operating position is about to move away from the limit position of its virtual operating range... endIt also becomes different from the steering angle θ, which is the rate of increase ν after the position of the steering wheel 11 has become far away from the limit position of its virtual operating range. end Therefore, the steering angle θ is immediately calculated using the increase ratio ν of the vehicle speed V based on the position immediately following the limit position of the steering wheel 11, which has become far from its virtual operating range. end At that time, there exists a steering angle θ. end Concerns about the rapid changes in its value.

[0194] In this respect, in this embodiment, when the operating position of the steering wheel 11 has moved away from the extreme position of its virtual operating range, the change of the speed increase ratio ν in each operating cycle is limited to the upper limit value ν. UL Or lower limit value ν LL Therefore, the method used to calculate the steering angle θ can be suppressed. end The final corrected growth rate ratio ν c The value changes rapidly. Correction for the growth rate ratio ν c The values ​​depend on the vehicle's steering state (in this article, steering angular velocity ω and steering angle θ). s The speed ratio ν, calculated by the speed ratio calculation unit 151, changes slowly over time from the driving state (vehicle speed V in this article) to the driving speed ratio ν. Therefore, the steering angle θ can be suppressed. end The virtual operating range of steering wheel 11 changes rapidly.

[0195] When the growth rate ν calculated by the growth rate calculation unit 151 is compared with the correction growth rate ν limited by the protection processing unit 169... 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 value of flag F6 is set to "0" by determination unit 168. Therefore, the limiting processing function for the growth rate ratio ν in protection processing unit 169 is disabled. Therefore, the growth rate ratio ν calculated by growth rate calculation unit 151 is used as the corrected growth rate ratio ν as the final growth rate ratio. c To calculate the steering angle θ end Without making any changes, that is, a more suitable steering angle θ corresponding to the growth ratio ν can be calculated based on the vehicle speed V. end .

[0196] Therefore, according to the third embodiment, in addition to the advantages shared with the first embodiment, the following advantages can also be obtained: Steering angle θ end The pinion angle θ can be calculated using the pinion angle calculation unit 61. p And the growth ratio ν is calculated based on the vehicle speed V. According to product specifications, it is conceivable that the requirement is to operate without using a limited vehicle speed V and steering angle θ. endCalculating the steering angle θ in the case of the mapping between the relationships M2 end And it can meet that requirement.

[0197] Fourth embodiment

[0198] 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.

[0199] like Figure 13 As shown, the correction processing unit 104 of the limiting axial force calculation unit 82 includes, in addition to the end determination unit 112, a turning determination unit 171, a deceleration determination unit 172, and an acceleration determination unit 173.

[0200] The turning determination unit 171 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 if the vehicle is turning. Lateral acceleration G y This refers to the lateral acceleration relative to the vehicle's direction of travel when the vehicle is turning. The turning determination unit 171 sets the value of flag F7 to indicate whether the vehicle is turning. When it is determined that the vehicle is turning, the turning determination unit 171 sets the value of flag F7 to "1". When it is determined that the vehicle is not turning, the turning determination unit 171 sets the value of flag F7 to "0". Details of the turning determination unit 171 will be described later.

[0201] Deceleration determination unit 172 receives longitudinal acceleration G detected by 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 parking light signal S generated by the parking 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. (Stop light signal S) stp This is an electrical signal indicating whether the parking lights located at the rear of the vehicle are on, thus indicating the driver's intention to decelerate. The deceleration determination unit 172 is based on longitudinal acceleration G. x Vehicle speed change ΔV and stop light signal S stpThe deceleration determination unit 172 determines whether the vehicle is decelerating. It 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 172 sets the value of flag F8 to "1". When it is determined that the vehicle is not decelerating, the deceleration determination unit 172 sets the value of flag F8 to "0". Details of the deceleration determination unit 172 will be described later.

[0202] Acceleration determination unit 173 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 173 is based on the longitudinal acceleration G. x Vehicle speed change ΔV and acceleration operation θ ap To determine if the vehicle is accelerating. Acceleration operation amount θ ap This refers to the amount of accelerator pedal operation and indicates the driver's acceleration intention. The acceleration determination unit 173 sets the value of the flag F9 to indicate whether the vehicle is accelerating. When it is determined that the vehicle is accelerating, the acceleration determination unit 173 sets the value of the flag F9 to "1". When it is determined that the vehicle is not accelerating, the acceleration determination unit 173 sets the value of the flag F9 to "0". Details of the acceleration determination unit 173 will be described later.

[0203] The vehicle speed calculation unit 113 receives the values ​​of flag F0 (end point determination result), flag F7 (turning determination result), flag F8 (deceleration determination result), and flag F9 (acceleration determination result). Figure 8 The determination unit 113A of the vehicle speed calculation unit 113, as described in parentheses, sets an indication based on the values ​​of sign F0, sign F7, sign F8, and sign F9 to calculate the steering angle θ. end The value of vehicle speed V will be fixed by the value of flag F3.

[0204] Similar to the first embodiment, the determining unit 113A sets the value of flag F3 based on the value of flag F0. The determining unit 113A sets the value of flag F3 independently of the value of flag F0, based on the values ​​of flags F7, F8, and F9.

[0205] When the value of flag F7 is "0", that is, when the vehicle is not turning, the determining unit 113A determines that the value of the vehicle speed V will not be fixed, and regardless of the values ​​of flags F8 and F9, the value of flag F3 will be set to "0". Therefore, the vehicle speed V detected by the vehicle speed sensor 501 is used to calculate the steering angle θ.end The final vehicle speed.

[0206] When both flag F7 and flag F8 are set to "1", that is, when the vehicle decelerates while turning, the determining unit 113A determines that the vehicle speed V will be fixed and sets flag F3 to "1". Therefore, as used to calculate the steering angle θ... end 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 113B. c Previous value V cn-1 .

[0207] When both flag F7 and flag F9 are set to "1", that is, when the vehicle accelerates while turning, the determining unit 113A determines that the vehicle speed V will be fixed and sets flag F3 to "1". Therefore, as used to calculate the steering angle θ... end 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 113B. c Previous value V cn-1 .

[0208] The turning determination unit 171 will be described in detail below. For example... Figure 14 As shown, the turning determination unit 171 includes two absolute value calculation units (ABS) 171A and 171B and three determination units 171C, 171D and 171E.

[0209] The absolute value calculation unit 171A calculates the lateral acceleration G calculated by the lateral acceleration sensor 502. y The absolute value. The absolute value calculation unit 171B calculates the steering angle θ calculated by the steering angle calculation unit 51. s The absolute value of.

[0210] The determining unit 171C receives the lateral acceleration G calculated by the absolute value calculation unit 171A. 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 The settings are based on the perspective used to determine whether the vehicle is turning. The determination unit 171C will use 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. ythAt that time, the determining unit 171C 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 171C sets the value of flag F10 to "1".

[0211] The determining unit 171D receives the steering angle θ calculated by the absolute value calculation unit 171B. 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 sth2 The setting is based on the eyepoint used to determine whether the vehicle is turning. The determining unit 171D sets 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 At that time, the determining unit 171D sets the value of flag F11 to "0". When the steering angle θ s The absolute value is greater than the steering angle threshold θ sth2 At that time, the determining unit 171D sets the value of flag F11 to "1".

[0212] The determining unit 171E receives the value of flag F10 set by the determining unit 171C and the value of flag F11 set by the determining unit 171D. The determining unit 171E sets the value of flag F7 based on the values ​​of flag F10 and flag F11 as a determination result indicating whether the vehicle is turning. When the value of at least one of flags F10 and F11 is "0", the determining unit 171E determines that the vehicle is not turning and sets the value of flag F7 to "0". When the values ​​of both flags F10 and F11 are "1", the determining unit 171E determines that the vehicle is turning and sets the value of flag F7 to "1".

[0213] Lateral acceleration threshold G yth and steering angle threshold θ sth2 It can be changed according to the vehicle speed V. The deceleration determination unit 172 will be described in detail below.

[0214] like Figure 15 As shown, the deceleration determination unit 172 includes four determination units 172A, 172B, 172C, and 172D. Determination unit 172A 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 ythl Longitudinal acceleration threshold G ythlThe setup is based on determining whether the vehicle is decelerating. The determination unit 172A measures the longitudinal acceleration G. x With longitudinal acceleration threshold G ythl 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 ythl At that time, the determining unit 172A sets the value of flag F12 to "0". When the longitudinal acceleration G x The value is greater than the longitudinal acceleration threshold G ythl At that time, the determining unit 172A sets the value of flag F12 to "1".

[0215] The determining unit 172B 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. thl Vehicle speed change threshold ΔV thl The settings are based on determining whether the vehicle is decelerating. The determination unit 172B compares the vehicle speed change ΔV per unit time with a vehicle speed change threshold ΔV. thl 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... thl When the value of the vehicle speed change ΔV per unit time is greater than the vehicle speed change threshold ΔV, the unit 172B sets the value of flag F13 to "0". thl At that time, the determining unit 172B sets the value of flag F13 to "1".

[0216] The determining unit 172C receives the parking light signal S generated by the parking light switch 505. stp When the parking light signal S stp When the parking lights are turned off, the determining unit 172C sets the value of flag F14 to "0". When the parking light signal S... stp When the parking lights are turned on, the determination unit 172C sets the value of flag F14 to "1".

[0217] The determining unit 172D receives the value of flag F12 set by the determining unit 172A, the value of flag F13 set by the determining unit 172B, and the value of flag F14 set by the determining unit 172C. The determining unit 172D 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 172D 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 172D determines that the vehicle is decelerating and sets the value of flag F8 to "1".

[0218] Longitudinal acceleration threshold G ythl And vehicle speed change threshold ΔV thl The speed can be changed according to the vehicle speed V. A configuration omitting the determination unit 172C can be used as the deceleration determination unit 172. In this case, when the value of at least one of the flags F12 and F13 is "0", the determination unit 172D sets the value of flag F8 to "0". When the values ​​of both flags F12 and F13 are "1", the determination unit 172D sets the value of flag F8 to "1".

[0219] The acceleration determination unit 173 will be described in detail below. For example... Figure 16 As shown, the acceleration determination unit 173 includes four determination units 173A, 173B, 173C and 173D.

[0220] The determining unit 173A 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 The setup is based on determining whether the vehicle is accelerating. The determination unit 173A 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 173A 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 173A sets the value of flag F15 to "1".

[0221] The determining unit 173B 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 The settings are based on determining whether the vehicle is accelerating. The determination unit 173B compares the vehicle speed change ΔV per unit time with a 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 173B sets the value of flag F16 to "0". th2 At that time, the determination unit 173B sets the value of flag F16 to "1".

[0222] The determining unit 173C receives the acceleration operation amount θ detected by the accelerator 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 The settings are based on determining whether the vehicle is accelerating. The determination unit 173C 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 determining unit 173C sets the value of flag F17 to "0". When the acceleration operation amount θ ap Greater than the acceleration operation threshold θ apth At that time, the determination unit 173C sets the value of flag F17 to "1".

[0223] The determining unit 173D receives the value of flag F15 set by the determining unit 173A, the value of flag F16 set by the determining unit 173B, and the value of flag F17 set by the determining unit 173C. The determining unit 173D 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 the value of at least one of flags F15, F16, and F17 is "0", the determining unit 173D determines that the vehicle is not accelerating and sets the value of flag F9 to "0". When the values ​​of all flags F15, F16, and F17 are "1", the determining unit 173D determines that the vehicle is accelerating and sets the value of flag F9 to "1".

[0224] Longitudinal acceleration threshold G yth2 And vehicle speed change threshold ΔV th2 The acceleration determination unit 173 can be adjusted according to the vehicle speed V. The determination unit 173 can be configured without the determination unit 173C. In this case, when at least one of the flags F15 and F16 is "0", the determination unit 173D sets the value of flag F9 to "0". When both flags F15 and F16 are "1", the determination unit 173D sets the value of flag F9 to "1".

[0225] 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 operating position of the steering wheel 11 has reached a position near the limit of its virtual operating range, when the vehicle is decelerating or accelerating while turning, the steering angle θ can be calculated. end The final vehicle speed correction vehicle speed V c Both are fixed at the vehicle speed before it is determined that the vehicle is decelerating while turning or accelerating while turning. Therefore, regardless of whether the operating position of the steering wheel 11 has reached a position near the limit of its virtual operating range, when the vehicle is decelerating while turning, the operating range of the steering wheel 11 does not narrow as the vehicle speed V decreases. Therefore, the steering wheel 11 is not rotated to push back in the opposite direction to the current steering direction. Therefore, the driver will not feel discomfort, such as a feeling of resistance. Regardless of whether the operating position of the steering wheel 11 has reached a position near the limit of its virtual operating range, when the vehicle is accelerating while turning, the operating range of the steering wheel 11 does not widen as the vehicle speed V increases. That is, since the current limit position of the operating range is maintained, the driver will not feel a so-called steering error. Therefore, regardless of whether the operating position of the steering wheel 11 has reached a position near the limit of its virtual operating range, changes in steering feel that are not desired by the driver can be suppressed when the vehicle is decelerating or accelerating while turning.

[0226] When using, in addition to longitudinal acceleration G x In addition to the vehicle speed change ΔV per unit time, it is also based on the stop light signal S. stp When the configuration for determining vehicle deceleration is used as deceleration determination unit 172, the vehicle deceleration can be determined more appropriately. For example, when a vehicle is traveling uphill, it is conceivable that the vehicle speed V decreases even if the driver does not intend to decelerate. In this respect, by taking into account the stop light signal S... stp This allows for a more accurate determination of the vehicle's deceleration based on the driver's intent on uphill roads.

[0227] When using, in addition to longitudinal acceleration Gx In addition to the vehicle speed change ΔV per unit time, it is also based on the acceleration operation amount θ ap When the configuration for determining vehicle acceleration is used as the acceleration determination unit 173, the vehicle's acceleration can be determined more appropriately. For example, when the vehicle is traveling downhill, it is conceivable that the vehicle speed V increases even if the driver does not intend to accelerate. In this respect, by considering the acceleration operation amount θ... ap This allows for a more accurate determination of the vehicle's acceleration on downhill roads based on the driver's intent.

[0228] Fifth embodiment

[0229] The steering control device according to the fifth embodiment will now be described. Basically, the steering control device according to this embodiment has the same characteristics as... Figures 1 to 9 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 end-point determination unit. This embodiment can be applied to the second to fourth embodiments.

[0230] like Figure 17 As shown, the end-point determination unit 112 is based on the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * To determine whether the operating position of the steering wheel 11 has reached the vicinity of the limit position of its virtual operating range, and to set the value of the flag F0 based on the determination result.

[0231] like Figure 18 As shown, the end-point determination unit 112 includes a determination unit 112E. The determination unit 112E receives the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * and the threshold θ stored in the storage device of the control device 50 pth Threshold θ pth This is a reference value used to determine whether the operating position of the steering wheel 11 has reached the vicinity of the limit position of its virtual operating range. Threshold θ pth Based on the pinion angle θ when the rotating shaft 14 is close to the limit of its physical operating range. p To set. Determine unit 112E will set the target pinion angle θ. p * With threshold θ pth The comparison is performed, and the value of flag F0 is set based on the comparison result. When the target pinion angle θ... p * The value is greater than the threshold θ pth When the target pinion angle θ is determined, the unit 112E sets the value of flag F0 to "1". p* The value is less than the threshold θ pth At that time, the determining unit 112E sets the value of the flag F0 to "0".

[0232] like Figure 17 As shown, a filter 181 can be set in the control device 50. The filter 181 adjusts the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * Filtering is performed. Therefore, the target pinion angle θ calculated by the target pinion angle calculation unit 62 is... p * The noise was removed.

[0233] Therefore, according to the fifth embodiment, in addition to the advantages of the first embodiment, the following advantages can also be obtained: Whether the operating position of the steering wheel 11 has reached the limit position of its virtual operating range can be determined using the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * To determine this. Depending on product specifications, it can be required that the steering angle θ is not used. end Steering angle θ s Given the vehicle speed V, determine whether the operating position of the steering wheel 11 has reached the vicinity of the limit position of its virtual operating range, and whether the requirement can be met.

[0234] Sixth embodiment

[0235] The steering control device according to the sixth embodiment will now be described. This embodiment differs from the fourth embodiment in the configuration of the turning determination unit.

[0236] like Figure 19 As shown, the turning determination unit 171 includes a slip angle calculation unit 191A and a determination unit 191B. The slip angle calculation unit 191A 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 The slip angle θ is calculated using the vehicle speed V. 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 191A calculates the slip angle θ using the mapping M9 stored in the storage device of the control device 50. sa Mapping M9 limits the steering angle θ 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 sAs the absolute value of θ increases and the vehicle speed V increases, the slip angle θ sa The absolute value increases.

[0237] The determining unit 191B receives the slip angle θ calculated by the slip angle calculation unit 191A. 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 The setting is based on the perspective used to determine whether the vehicle is turning. The determining unit 191B will set the slip angle θ. sa The absolute value and the slip angle threshold θ sath 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 At that time, determining unit 191B determines that the vehicle is not turning and sets the value of 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 191B determines that the vehicle is turning and sets the value of the flag F7 to "1".

[0238] Therefore, according to the sixth 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 turning.

[0239] Seventh embodiment

[0240] The steering control device according to the seventh embodiment will now be described. This embodiment differs from the fourth embodiment in the arrangement of the turning determination unit, the deceleration determination unit, and the acceleration determination unit.

[0241] The vehicle's wheels are rotatably supported on the vehicle body via hub unit bearings, and tire force sensors for detecting tire force can be installed in each hub unit bearing. Tire force is the load acting between the road surface and each wheel.

[0242] like Figure 20 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. yThe force acting in the Z-axis direction of each wheel is called the vertical load (vertical force) F. z The torque acting around the X-axis of each wheel is called the rolling torque 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 vehicle is called the yaw moment M. z .

[0243] When such a tire force sensor is provided, the following configuration can be used as the turning determination unit 171, the deceleration determination unit 172, and the acceleration determination unit 173. For example... Figure 21 As shown, the turning determination unit 171 includes three absolute value calculation units (ABS) 201A, 201B and 201C and four determination units 201D, 201E, 201F and 201G.

[0244] The absolute value calculation unit 201A calculates the lateral load F detected by the tire force sensor. y The absolute value. The absolute value calculation unit 201B calculates the yaw moment M detected by the tire force sensor. z The absolute value of.

[0245] The absolute value calculation unit 201C calculates the rolling torque M detected by the tire force sensor. x The absolute value of the load. The determining unit 201D receives the lateral load F calculated by the absolute value calculation unit 201A. 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 The setup is based on the perspective used to determine whether the vehicle is turning. The determination unit 201D 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 determination unit 201D 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 201D sets the value of flag F18 to "1".

[0246] The determining unit 201E receives the yaw moment M calculated by the absolute value calculation unit 201B. 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 zthThe settings are based on the perspective of determining whether the vehicle is turning. The determination unit 201E 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, it is determined that unit 201E will set 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 201E sets the value of flag F19 to "1".

[0247] The determining unit 201F receives the rolling torque M calculated by the absolute value calculation unit 201C. x The absolute value and the rolling torque threshold M stored in the storage device of the control device 50 xth Rolling torque threshold M xth The settings are based on the perspective of determining whether the vehicle is turning. The determination unit 201F will determine the rolling torque M. x The absolute value of the rolling torque threshold M xth The comparison is performed, and the value of flag F20 is set based on the comparison result. When the rolling torque M... x The absolute value is less than the rolling torque threshold M xth When the rolling torque M is at that time, the unit 201F will set the value of flag F20 to "0". x The absolute value is greater than the rolling torque threshold M xth At that time, the determination unit 201F sets the value of flag F20 to "1".

[0248] The determining unit 201G receives the value of flag F18 set by the determining unit 201D, the value of flag F19 set by the determining unit 201E, and the value of flag F20 set by the determining unit 201F. The determining unit 201G sets the value of flag F7 based on the values ​​of flags F18, F19, and F20 as a determination result indicating whether the vehicle is turning. When the value of at least one of flags F18, F19, and F20 is "0", the determining unit 201G determines that the vehicle is not turning and sets the value of flag F7 to "0". When the values ​​of all flags F18, F19, and F20 are "1", the determining unit 201G determines that the vehicle is turning and sets the value of flag F7 to "1".

[0249] like Figure 22 As shown, the deceleration determination unit 172 includes four determination units 211A, 211B, 211C, and 211D. Determination unit 211A 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 xthl Longitudinal load threshold F xthl The settings are based on determining whether the vehicle is decelerating. The determination unit 211A will determine the longitudinal load F. x With longitudinal load threshold F xthl 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 xthl When the longitudinal load F is applied, the determining unit 211A sets the value of flag F21 to "0". x The value is greater than the longitudinal load threshold F xthl At that time, the determining unit 211A sets the value of the flag F21 to "1".

[0250] The determining unit 211B receives the vertical load F calculated by the tire force sensor. z and the vertical load threshold F stored in the storage device of the control device 50 zthl Vertical load threshold F zthl The setup is based on determining whether the vehicle is decelerating. The determination unit 211B will apply the vertical load F... z With vertical load threshold F zthl 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 zthl When the vertical load F is applied, the determining unit 211B sets the value of flag F22 to "0". z The value is greater than the vertical load threshold F zthl At that time, the determining unit 211B sets the value of flag F22 to "1".

[0251] The determining unit 211C receives the pitching moment M calculated by the tire force sensor. y and the pitch moment threshold M stored in the storage device of the control device 50 ythl Pitch moment threshold M ythl The settings are based on determining whether the vehicle is decelerating. The determination unit 211C will determine the pitch moment M. y With pitch moment threshold M ythl 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 ythl At that time, the determination unit 211C sets the value of flag F23 to "0". When the pitch moment M y The value is greater than the pitch moment threshold M ythlAt that time, the determining unit 211C sets the value of flag F23 to "1".

[0252] Determining unit 211D receives the value of flag F21 set by determining unit 211A, the value of flag F22 set by determining unit 211B, and the value of flag F23 set by determining unit 211C. Determining unit 211D sets the value of flag F8 based on the values ​​of flags F21, F22, and F23 as a determination result indicating whether the vehicle is decelerating. When the value of at least one of flags F21, F22, and F23 is "0", determining unit 211D determines that the vehicle is not decelerating and sets the value of flag F8 to "0". When the values ​​of all flags F21, F22, and F23 are "1", determining unit 211D determines that the vehicle is decelerating and sets the value of flag F8 to "1".

[0253] like Figure 23 As shown, the acceleration determination unit 173 includes four determination units 221A, 221B, 221C, and 221D. Determination unit 221A 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 xth2 Longitudinal load threshold F xth2 The settings are based on the perspective of determining whether the vehicle is accelerating. The determination unit 221A 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 221A 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 221A sets the value of flag F24 to "1".

[0254] The determining unit 221B receives the vertical load F calculated 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 The setup is based on determining whether the vehicle is accelerating. The determination unit 221B 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 zth2When the vertical load F is applied, the determining unit 221B sets the value of flag F25 to "0". z The value is greater than the vertical load threshold F zth2 At that time, the determining unit 221B sets the value of flag F25 to "1".

[0255] The determining unit 221C receives the pitching moment M calculated 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 The settings are based on determining whether the vehicle is accelerating. The determination unit 221C 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 When the pitch moment M is at that time, the determination unit 221C sets the value of flag F26 to "0". y The value is greater than the pitch moment threshold M yth2 At that time, the determining unit 221C sets the value of flag F26 to "1".

[0256] Determining unit 221D receives the value of flag F24 set by determining unit 221A, the value of flag F25 set by determining unit 221B, and the value of flag F26 set by determining unit 221C. Determining unit 221D sets the value of flag F9 based on the values ​​of flags F24, F25, and F26 as a determination result indicating whether the vehicle is accelerating. When the value of at least one of flags F24, F25, and F26 is "0", determining unit 221D determines that the vehicle is not accelerating and sets the value of flag F9 to "0". When the values ​​of all flags F24, F25, and F26 are "1", determining unit 221D determines that the vehicle is accelerating and sets the value of flag F9 to "1".

[0257] Therefore, according to the seventh embodiment, the following advantages can be obtained. When a tire force sensor is installed in each wheel of the vehicle, it is possible to determine whether the vehicle is turning, decelerating, or accelerating based on the tire force detected by the tire force sensor.

[0258] Eighth embodiment

[0259] The steering control device according to the eighth embodiment will now be described. This embodiment differs from the first embodiment in the configuration of the limiting axial force calculation unit 82.

[0260] like Figure 24As shown, the limiting axial force calculation unit 82 includes a correction processing unit 230. The correction processing unit 230 includes a differentiator 230A, a gain calculation unit 230B, and a protection processing unit 230C.

[0261] Differentiator 230A processes the steering angle θ calculated by steering angle calculation unit 51. s The steering angular velocity ω is calculated by differentiation. The gain calculation unit 230B calculates the gain G based on the steering angular velocity ω calculated by the differentiator 230A. c The gain calculation unit 230B 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 "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", regardless of the increase in the absolute value of the steering angular velocity ω, the gain G... c The value of ω remains "1". th2 The setting is based on the steering angular velocity ω when the steering wheel 11 is in a holding steering state or when the steering wheel 11 is turning slowly.

[0262] Protection processing unit 230C receives the steering angle θ calculated by steering angle calculation unit 101. end and the gain G calculated by the gain calculation unit 230B c The protection processing unit 230C will turn the steering angle θ. end The variation in each operating cycle is limited to the limit value Δθ end Limit value Δθ end Based on suppressing the steering angle θ end The setting is based on the rapidly changing perspective. Limit value Δθ end It can be a fixed value or it can be based 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 230C controls the limit value Δθ. end Multiply by gain G c To calculate the final limit value Δθ end .

[0263] When the gain G c When the value of is "0", the final limit value Δθ endIt is "0", and therefore the turning angle θ end 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 turning angle θ end 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 steering angle θ end The variation in each operating cycle is limited to the limit value Δθ end .

[0264] The operation of the eighth 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 turning in the specified state, the steering angular velocity ω is "0". At this time, due to the gain G... c The value is "0", therefore the steering angle θ end The variation in each operating cycle is limited to "0". Therefore, the final steering angle θ used to calculate the limiting axial force AF4 is... end Corrected steering angle θ endc It is fixed to be based on the condition that the steering wheel 11 is in a holding steering state (more precisely, when the steering angular velocity ω has reached or is less than a threshold ω). th2 The steering angle θ of the vehicle speed V when the value is given. end The same value, regardless of changes in vehicle speed V. That is, correcting the steering angle θ. endc The value does not change with the vehicle speed V.

[0265] Therefore, when the vehicle is held at a constant steering angle θ by steering wheel 11 s When the vehicle is decelerating at a constant speed V, the operating range of the steering wheel 11 does not narrow as the vehicle speed V decreases. Therefore, the steering wheel 11 is not rotated in a way that pushes it back in the opposite direction to the current steering direction. Thus, the driver will not experience discomfort, such as a feeling of resistance. When the vehicle is decelerating at a constant steering angle θ, the steering wheel 11 remains within a constant steering angle θ. s When accelerating, the steering wheel 11's operating range does not widen with increasing vehicle speed V. That is, because the current limit of the operating range is maintained, the driver does not experience any so-called steering error. In this way, even when the vehicle speed V is maintained at a constant steering angle θ, the steering wheel 11 remains within a constant range. s When the steering conditions change, it can also suppress changes in steering feel that the driver does not want.

[0266] When the steering wheel 11 is turned slowly at a steering angular velocity ω equal to or less than the threshold, the steering end angle θ is corrected. endcThe value is fixed similarly to the case where the steering wheel 11 is in a holding steering state.

[0267] Then, when restarting steering wheel 11, the following concerns arise. Specifically, it is conceivable that the corrected steering angle θ, fixed just before restarting steering wheel 11, needs to be adjusted. endc The value becomes different from the steering angle θ calculated by the steering angle calculation unit 101 immediately after the steering wheel 11 is restarted. end The value of .

[0268] In this respect, when the steering angular velocity ω becomes greater than the threshold ω due to the restarting of steering wheel 11... th2 At that time, the gain G c The value is set to, for example, "1". Therefore, even when the steering angle θ is calculated immediately after restarting steering wheel 11... end The value becomes different from the corrected steering angle θ that was fixed before the steering wheel 11 was about to be restarted. endc When the value is θ, the steering angle θ end The variation in each operating cycle is also limited to a limit value Δθ by the protection processing unit 230C. end Therefore, the final steering angle θ used to calculate the limiting axial force AF4 is... end Corrected steering angle θ endc As time slowly changes, the steering angle θ is calculated by the steering angle calculation unit 101. end That is, it can suppress the correction of the steering angle θ. endc The value changes rapidly.

[0269] Therefore, according to the eighth embodiment, in addition to the advantages of the first embodiment, the following advantages can also be obtained: The steering angle θ can be determined using an electrical signal (in this text, steering angular velocity ω) as a state variable reflecting the steering state. end The correction is performed without performing determination processes such as determining the end of the steering wheel 11.

[0270] In addition, it can be adopted with Figure 8 The same configuration as the vehicle speed calculation unit 113 shown in the first embodiment is used as the correction processing unit 230. In this case, a correction processing unit 230 is provided. Figure 24 The gain calculation unit 230B shown replaces the determination unit 113A. Switch 113C receives the gain G. c Instead of the F3 symbol, the vehicle speed V is affected by the steering angle θ. end Replace and correct vehicle speed V c Corrected steering angle θ endc Replacement. Upper limit calculation unit 113D calculates the steering angle θ.end The upper limit of the change in each operating cycle, rather than the temporary vehicle speed value V. temp The upper limit of the change V in each operating cycle UL The lower limit calculation unit 113E calculates the steering angle θ. end The lower limit of the change in each operating cycle, not the temporary vehicle speed value V. temp The lower limit of the change in each operating cycle, V LL Unit 113G determines the steering angle θ. end Whether the change in each operating cycle is restricted, and setting the value of flag F4 to indicate its determination result. The protection processing unit 113H will turn the steering angle θ. end 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 eighth embodiments can also be obtained.

[0271] It can be adopted with Figure 12 The same configuration as the correction processing unit 160 shown according to the third embodiment is used as the correction processing unit 230. In this case, a correction processing unit 230 is provided. Figure 24 The gain calculation unit 230B shown replaces the end determination units 162 and 163. The speed ratio ν is determined by the steering end angle θ. end Replace and correct the growth rate ratio ν c Corrected steering angle θ endc Replacement. Upper limit calculation unit 166 calculates the steering angle θ. end The upper limit of the change in each operating cycle, rather than the upper limit of the change in the rate of increase of ν in each operating cycle. UL The lower limit calculation unit 113E calculates the steering angle θ. end 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 169 will adjust the steering angle θ. end 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 eighth embodiments can be obtained in this case.

[0272] Ninth embodiment

[0273] The steering control device according to the ninth embodiment will now be described. This embodiment differs from the first embodiment in the configuration of the steering reaction force command value calculation unit 52.

[0274] like Figure 25As shown, the steering reaction force command value calculation unit 52 includes an adder 241, a target steering torque calculation unit 242, a torque feedback control unit 243, an axial force calculation unit 244, a target steering angle calculation unit 245, a steering angle feedback control unit 246, and an adder 247.

[0275] Adder 241 inputs the first steering reaction force command value T calculated by torque feedback control unit 243. 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 * .

[0276] The target steering torque calculation unit 242 is based on the input torque T calculated by the adder 241. 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 242 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.

[0277] The torque feedback control unit 243 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 242 h * The torque feedback control unit 243 controls the steering torque T. h The feedback control is used to calculate the first steering reaction force command value T. 11 * This makes the steering torque T detected by the torque sensor 34... h With the target steering torque T h * Consistent.

[0278] Axial force calculation unit 244, for example, is based on pinion angle θ p The current I of the rotating motor 41 b The axial force acting on the pivot 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 .

[0279] The target steering angle calculation unit 245 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 243 11 * The converted torque value T calculated by the axial force calculation unit 244 af The vehicle speed V detected by vehicle speed sensor 501. The target steering angle calculation unit 245 is based on the steering torque T. h First steering reaction force command value T 11 * The converted torque value T af The target steering angle θ of steering wheel 11 is calculated using the vehicle speed V. s * .

[0280] The target steering angle calculation unit 245 calculates the target steering angle from the command value T, which is the first steering reaction force. 11 * and steering torque T h The sum of the input torque T in * Subtract the converted torque value T af The final input torque T of the steering wheel 11 is calculated based on the steering reaction force of the axial force. in * The target steering angle calculation unit 245 is based on the final input torque T. in * The target steering angle θ is calculated using an ideal model expressed by the following expression (A6). s * Based on the premise that the steering wheel 11 is mechanically connected to the rotating wheel 16 and the steering system of the rotating wheel 16, the system is based on the input torque T. in * The ideal model is obtained by modeling the steering angle of the steering wheel 11 corresponding to the ideal steering angle.

[0281] T in * =Jθ s +Cθ s '+Kθ s …(A6)

[0282] 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 coefficient of viscosity (coefficient of friction) corresponding to the friction of the shaft 14 relative to the housing, and "K" represents the spring coefficient when the steering wheel 11 and steering shaft 12 are considered as springs. The coefficient of viscosity C and the coefficient of inertia J have values ​​based on the vehicle speed V. s "" represents the steering angle θs The second derivative value of θ, and "θ s '" represents the steering angle θ s The first-order differential value.

[0283] Steering angle feedback control unit 246 receives the steering angle θ calculated by steering angle calculation unit 51. s and the target steering angle θ calculated by the target steering angle calculation unit 245 s * The steering angle feedback control unit 246 controls the steering angle θ. s The feedback control is used to calculate the second steering reaction force command value T. 12 * This makes the actual steering angle θ calculated by the steering angle calculation unit 51... s With the target turning angle θ s * Consistent.

[0284] Adder 247 inputs the second steering reaction force command value T calculated by steering angle feedback control unit 246. 12 * The first steering reaction force command value T calculated by the torque feedback control unit 243 11 * The values ​​are added together to calculate the steering reaction force command value T. * .

[0285] The axial force calculation unit 244 will be described in detail below. For example... Figure 26 As shown, the axial force calculation unit 244 includes a limiting axial force calculation unit 251, an angular axial force calculation unit 252, a current axial force calculation unit 253, a maximum value selection unit 254, an axial force distribution calculation unit 255, and a converter 256.

[0286] The limiting axial force calculation unit 251 is based on the target pinion angle θ calculated by the target pinion angle calculation unit. p * The limiting axial force AF4 is calculated. The limiting axial force calculation unit 251 uses the mapping M11 stored in the storage device of the control device 50 to calculate the limiting axial force AF4.

[0287] like Figure 27 As shown, mapping M11 is used to define the target pinion angle θ. p * A two-dimensional mapping relating the relationship with the limiting axial force AF4, and possessing the following characteristics. That is, when the target pinion angle θ... p * The absolute value is equal to or less than the threshold θ pth2 At that time, the value of the limiting axial force AF4 remains "0". When the target pinion angle θp * The absolute value is greater than the threshold θ pth2 At that time, the value of the limiting axial force AF4 changes with the target pinion angle θ. p * It increases rapidly as the absolute value increases.

[0288] The limiting axial force calculation unit 251 can be based on the target pinion angle θ calculated by the target pinion angle calculation unit. p * The limiting axial force AF4 is calculated based on the vehicle speed V detected by the vehicle speed sensor 501.

[0289] The angular axial force calculation unit 252 has the same characteristics as... Figure 4 The angular axial force calculation unit 252 shown has the same function as the angular axial force calculation unit 91 according to the first embodiment. The angular axial force calculation unit 252 is based on the target pinion angle θ. p * To calculate the angular axial force AF1, which is the ideal value of the axial force acting on the rotating shaft 14.

[0290] The current axial force calculation unit 253 has the same characteristics as... Figure 4 The axial force calculation unit 91 shown in the first embodiment has the same function. The current axial force calculation unit 253 is based on the current I of the rotating motor 41. b The value is used to calculate the current axial force AF2 acting on the rotating shaft 14.

[0291] The maximum value selection unit 254 receives the limiting axial force AF4 calculated by the limiting axial force calculation unit 251 and the angular axial force AF1 calculated by the angular axial force calculation unit 252. The maximum value selection unit 254 selects the axial force with the larger absolute value between the limiting axial force AF4 and the angular axial force AF1, and sets the selected limiting axial force AF4 or the angular axial force AF1 as the selected axial force AF6.

[0292] The axial force distribution calculation unit 255 has the same characteristics as... Figure 4 The axial force distribution calculation unit 255, as shown in the first embodiment, has the same function. The axial force distribution calculation unit 255 sets the distribution ratio of the selected axial force AF6 and the current axial force AF2 based on various state variables reflecting vehicle behavior, steering state, or road surface state. The axial force distribution calculation unit 255 calculates the combined axial force AF7 by adding the values ​​obtained by multiplying the distribution ratios set for the selected axial force AF6 and the current axial force AF2 respectively.

[0293] The converter 256 calculates the converted torque value T by converting the combined axial force AF7 calculated by the axial force distribution calculation unit 255 into torque. afBased on this configuration, such as Figure 26 As indicated by the double-dotted line, a correction processing unit 257 is provided in the axial force calculation unit 244 to correct the limiting axial force AF4 calculated by the limiting axial force calculation unit 251. The correction processing unit 257 has... Figure 12 The configuration shown is the same as that of the correction processing unit 160 according to the third embodiment. The speed increase ratio ν is replaced by the limiting axial force AF4, and the speed increase ratio ν is corrected. c The axial force limit is replaced by the corrected limit force. The upper limit calculation unit 166 calculates the upper limit value of the change in the axial force limit AF4 per operating cycle, instead of the upper limit value ν of the change in the rate of increase ν per operating cycle. UL The lower limit calculation unit 113E calculates the lower limit value of the change in the limiting axial force AF4 per operating cycle, rather than the lower limit value ν of the change in the growth rate ratio ν per operating cycle. LL The protection processing unit 169 limits the variation of the axial force AF4, rather than the speed increase ratio ν, to an upper or lower limit value per operating cycle. In this case, the same advantages as the first embodiment can also be obtained.

[0294] Other embodiments

[0295] The above implementation can be modified as follows. In the above implementation, a clutch can be provided in the steering system 10. In this case, as... Figure 1 As indicated by the double-dotted line, 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 connection / disconnection of power by controlling the power supply to the excitation coil. The control device 50 performs the connection / disconnection control of switching the clutch 21 between engagement and disengagement. When the clutch 21 is disengaged, the power transmission between the steering wheel 11 and the steering wheel 16 is mechanically cut off. When the clutch 21 is engaged, the power transmission between the steering wheel 11 and the steering wheel 16 is mechanically established.

[0296] In the foregoing embodiments, the steering system 10 can be a laterally independent steering system that independently rotates the two 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 reaction motor that generates a steering reaction force applied to a steering wheel, wherein power transmission between the steering wheel and the rotating wheels is interrupted, the steering control device (50) being characterized in that it comprises: A first processor (101) is configured to: change the virtual operating range of the steering wheel according to the steering state or vehicle state by controlling the reaction motor; as well as A second processor is configured to: when the steering wheel's operating position reaches a position near the limit of the virtual operating range, adjust the degree of change in the virtual operating range of the steering wheel based on the steering state or the vehicle state. The first processor (101) is configured to calculate the limit value of the virtual operating range of the steering wheel based on the value of the vehicle speed, and The second processor is configured to fix the vehicle speed value used to calculate the limit value when the steering wheel operation position reaches a position near the limit position of the virtual operation range.

2. The steering control device (50) according to claim 1, wherein, The first processor (101) is configured to: calculate the limit value of the virtual operating range of the steering wheel by dividing the rotation angle of the shaft that rotates with the rotational operation of the rotating wheel by the speed increase ratio between the steering wheel and the shaft calculated based on the vehicle speed; The second processor is configured to limit the change per unit time of the growth rate ratio used to calculate the limit value when the steering wheel's operating position reaches a position near the limit position of the virtual operating range.

3. The steering control device (50) according to claim 1, wherein, The first processor (101) is configured to calculate the limit value of the virtual operating range of the steering wheel based on the value of the vehicle speed, and The second processor is configured to limit the variation of the limit value calculated by the first processor (101) per unit time when the steering wheel is held at a constant steering angle relative to the neutral position of the steering wheel.

4. The steering control device (50) according to claim 1, characterized in that, It also includes a third processor (251) configured to calculate a limiting axial force reflected in the steering reaction force based on a target rotation angle of the shaft that rotates with the operation of the shaft that causes the rotating wheel to rotate, and the vehicle speed, to virtually limit the operation of the steering wheel, the limiting axial force being the axial force of the shaft. The second processor is configured to limit the change in the limiting axial force per unit time calculated by the third processor (251) when the steering wheel's operating position reaches a position near the limit position of the virtual operating range.

5. The steering control device (50) according to claim 1, wherein, The second processor is configured to: when the operating position of the steering wheel moves away from the position near the limit of the virtual operating range, slowly change the value of the vehicle speed used to calculate the limit value of the virtual operating range of the steering wheel to the current value of the vehicle speed detected by the vehicle speed sensor.

6. The steering control device (50) according to claim 2, wherein, The second processor is configured to: when the operating position of the steering wheel becomes far away from the position near the limit of the virtual operating range, the value of the growth rate used to calculate the limit value of the virtual operating range of the steering wheel is slowly changed to the current value of the growth rate calculated by the first processor (101).

7. The steering control device (50) according to claim 3, wherein, The second processor is configured to: when the state in which the steering wheel is held at the constant steering angle relative to the neutral position of the steering wheel is released, to slowly change the limit value of the virtual operating range of the steering wheel to the current limit value calculated by the first processor (101).

8. The steering control device (50) according to claim 4, wherein, The second processor is configured to: when the operating position of the steering wheel becomes far away from the position near the limit position of the virtual operating range, slowly change the value of the limiting axial force reflected in the steering reaction force to the current limiting axial force calculated by the third processor (251).

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