Steering gear

Abstract

To provide a steering apparatus capable of improving operability.SOLUTION: A steering apparatus includes a steering unit, a turning unit, and a control device. Power transmission between the steering unit and turning wheels of a vehicle is cut off. The steering unit includes: a lever which is operated when the vehicle is turned; and an inclination angle sensor which detects an operation mount of the lever. The turning unit includes a turning motor which generates force for turning the turning wheels. The control device controls the turning motor according to the operation amount of the lever. The control device is configured to execute smoothing processing on the operation amount of the lever detected through the inclination angle sensor (Step S102).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a steering device. [Background technology]

[0002] Conventionally, there has been a so-called steer-by-wire steering device in which power transmission between the steering wheel and the steered wheels is separated. The steering device has a steering unit having a steering wheel and a steering unit that generates a force for steering the steered wheels. The steering wheel is an operator that is operated by the driver. In recent years, various operators other than the steering wheel have been proposed, taking advantage of the fact that the steering unit and the steering unit are not mechanically connected. For example, Patent Documents 1 and 2 describe steering devices that use a joystick as an operator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 5,086,870 [Patent Document 2] Japanese Patent Application Publication No. 8-34353 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, the rotation angle range of a steering wheel is 360° or more. The tilt angle of a joystick is, for example, about 10° to 15°. That is, the tilt angle range of a joystick is much narrower than the rotation angle range of a steering wheel. Therefore, the amount of joystick operation required to steer the steered wheels by the same angle can be much smaller than the amount of steering wheel operation.

[0005] Using a joystick can reduce the burden on the operator. However, the amount of change in the steering angle relative to the amount of joystick operation is much greater than the amount of change in the steering angle relative to the amount of steering wheel operation. In other words, even a small tilt of the joystick can result in a large change in the steering angle. This can lead to, for example, excessive steering, which can reduce operability. [Means for solving the problem]

[0006] A steering device that can solve the above problem includes a steering unit in which power transmission between the steered wheels of a vehicle is separated, the steering unit having an operator operated when turning the vehicle and a sensor configured to detect the amount of operation of the operator, a steering unit having a motor that generates a force for turning the steered wheels, and a control device configured to control the motor in accordance with the amount of operation of the operator. The control device is configured to perform a smoothing process on the amount of operation of the operator detected by the sensor.

[0007] For example, the position of the operator may change slightly unintentionally due to the influence of vehicle behavior. In this regard, the above-described steering device eliminates minute changes in the amount of operation caused by minute changes in the position of the operator. This prevents unintended changes in the position of the operator from being reflected in the steering angle of the steered wheels. Therefore, the steered wheels can be steered as intended by the operator.

[0008] In the above steering device, the control device may be configured to execute a process for adjusting the steering angle of the steered wheels in accordance with the vehicle speed. According to this configuration, the steered wheels can be steered appropriately according to the vehicle speed.

[0009] In the above steering device, the operator may be configured to be operable in the left-right direction and the front-rear direction relative to the traveling direction of the vehicle. The sensor may be configured to detect the amount of operation of the operator in the left-right direction and the amount of operation of the operator in the front-rear direction. The control device may be configured to control the motor so that the steered wheels are steered in accordance with the amount of operation of the operator in the left-right direction. The control device may also be configured to execute processing to correct the amount of operation of the operator in the left-right direction in accordance with the amount of operation of the operator in the front-rear direction.

[0010] If the operator is configured to be operable left and right and forward and backward relative to the vehicle's traveling direction, the operator may unconsciously operate the operator left and right while operating the operator forward or backward, which may result in the operator operating the operator to a different amount than intended.

[0011] In this regard, with the above-described configuration, the amount of left-right operation of the operator is corrected according to the amount of forward-backward operation of the operator. This correction process allows the amount of left-right operation to approach the amount of operation that corresponds to the actual amount of operation intended by the operator. Therefore, the operator can steer the vehicle as intended.

[0012] In the above steering device, the control device may be configured to execute a process for limiting the steering angular velocity of the steered wheels in accordance with the vehicle speed. According to this configuration, the steered wheels can be steered at an appropriate steering angular velocity according to the vehicle speed.

[0013] In the above steering device, the control device may be configured to calculate a target value of a vehicle state quantity that reflects a turning state of the vehicle based on the steered state of the steered wheels, calculate a correction amount to be reflected in the steering angle of the steered wheels by executing feedback control that causes an actual value of the vehicle state quantity to follow the target value, and execute processing to reflect the correction amount in the steering angle.

[0014] This configuration maintains the turning state of the vehicle according to the steering state of the steered wheels. Therefore, for example, when traveling on a canted road, the occurrence of so-called vehicle drift can be suppressed. A canted road is a linear slope that slopes in the vehicle width direction, perpendicular to the vehicle's direction of travel. Vehicle drift occurs when the vehicle is affected by the slope of the canted road and gradually descends toward the lower side of the canted road as the vehicle moves forward.

[0015] In the above steering device, the control device is configured to calculate a target rotation angle of a shaft that rotates in conjunction with the steered wheels in accordance with the amount of operation of the operator, and to control the motor so that the actual angle of the shaft follows the target rotation angle.

[0016] According to this configuration, the turning angle of the steered wheels can be controlled by controlling the rotation angle of the shaft that rotates in conjunction with the steered wheels. In the above steering device, the control device may be configured to increase the target rotation angle by a predetermined second update value each time the operation amount of the operator increases by a predetermined first update value.

[0017] According to this configuration, it is possible to suppress excessive changes in the steering angle of the steered wheels in response to minute operations of the operating element. In the above-mentioned steering device, the control device may be configured to control the motor when the target rotation angle changes so that the deviation between the target rotation angle and the actual angle of the shaft becomes zero over a predetermined gradual change period.

[0018] This configuration allows the actual angle of the shaft to change more smoothly in response to changes in the target rotation angle. This allows the steered wheels to be steered more smoothly. It also prevents the vehicle behavior from changing too sensitively in response to the operation of the control.

[0019] In the above steering device, the control device may be configured to adjust the gradual change period in accordance with a vehicle speed. According to this configuration, the gradual change period can be set to an appropriate time according to the vehicle speed V.

[0020] In the above-mentioned steering device, the control device may be configured to calculate the target rotation angle so that the absolute value of the target rotation angle has a hysteresis characteristic with respect to a change in the operation amount of the operator when a turning operation and a returning operation are performed through the operator.

[0021] According to this configuration, a more appropriate target rotation angle can be set in accordance with the operation state of the operator, and therefore the steered wheels can be steered more appropriately in accordance with the operation state of the operator.

[0022] In the above steering device, the control device may be configured to calculate the target rotation angle so that the rate of change in the target rotation angle relative to the change in the operation amount of the operator becomes larger as the operation amount of the operator increases.

[0023] This configuration can suppress changes in vehicle behavior caused by small, unintended changes in the amount of operation of the operator in a range where the amount of operation of the operator is small. Furthermore, in a range where the amount of operation of the operator is large, the responsiveness of the steering angle to the operation of the operator can be improved. Vehicle maneuverability is also improved.

[0024] In the above steering device, the operator may be a lever. The above steering device is suitable for a lever, as it is difficult to finely adjust the operating position of the lever. [Effects of the Invention]

[0025] According to the steering device of the present invention, it is possible to improve operability. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a configuration diagram of a first embodiment of a steering device. [Figure 2]FIG. 2 is a block diagram of a control device according to the first embodiment. [Figure 3] 5 is a flowchart showing a processing procedure of the control device according to the first embodiment. [Figure 4] 4 is a graph showing a first map that defines the relationship between the lever tilt angle and the target pinion angle according to the first embodiment. [Figure 5] 6 is a graph showing a second map that defines the relationship between the vehicle speed and the first gain according to the first embodiment. [Figure 6] 1 is a front view of a display device showing an example of a notification mode according to a first embodiment. FIG. [Figure 7] 3(a) and 3(b) are front views of a display device showing an example of a notification mode according to the first embodiment. [Figure 8] 1 is a front view of a display device showing an example of a notification mode according to a first embodiment. FIG. [Figure 9] 10 is a flowchart showing a processing procedure of a control device according to a second embodiment. [Figure 10] 10 is a graph showing a third map that defines the relationship between the lever tilt angle in the longitudinal direction and the second gain according to the second embodiment. [Figure 11] 10 is a graph showing a fourth map that defines the relationship between the vehicle speed and the limit value for the pinion angular velocity according to the second embodiment. [Figure 12] FIG. 10 is a block diagram of a correction processing unit according to a second embodiment. [Figure 13] 10 is a flowchart showing a processing procedure of a control device according to a third embodiment. [Figure 14] 10 is a graph showing a fifth map that defines the relationship between the lever tilt angle and the target pinion angle according to the third embodiment. [Figure 15] 10 is a graph showing changes over time in the target pinion angle and the actual pinion angle according to the third embodiment. [Figure 16] 10 is a graph showing a sixth map that defines the relationship between the vehicle speed and the set time T according to the fourth embodiment. [Figure 17]10 is a graph showing a seventh map that defines the relationship between the lever tilt angle and the target pinion angle according to the fifth embodiment. [Figure 18] 13 is a flowchart showing a processing procedure of a control device according to a fifth embodiment. [Figure 19] 13 is a graph showing the magnitude relationship between the pinion angle and the output value of the seventh map during a steering-back operation according to the fifth embodiment. [Figure 20] 13 is a graph showing the magnitude relationship between the pinion angle and the output value of the seventh map during a turning operation according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0027] First Embodiment A first embodiment of the steering device will be described below. <Overall structure> As shown in FIG. 1, the steering device 1 is a steer-by-wire type steering device. The steering device 1 has a steering unit 2, a turning unit 3, and a control device 4. The steering unit 2 is a mechanical part that is operated by the driver when changing the direction of travel of the vehicle. The turning unit 3 is a mechanical part for steering the steered wheels 5 of the vehicle. Mechanical power transmission between the steering unit 2 and the turning unit 3 is separated. The control device 4 controls the operation of the turning unit 3 according to the operating state of the steering unit 2.

[0028] The steering unit 2 has a base 2A and a lever 2B. The base 2A supports the lever 2B so that it can tilt. The lever 2B is an operator operated by an operator. The operator includes the driver of the vehicle. The lever 2B can be tilted, for example, left and right relative to the traveling direction of the vehicle. When no operating force is applied to the lever 2B, the lever 2B is maintained in a neutral position. The neutral position is a position of the lever 2B that corresponds to the straight-ahead state of the vehicle. When the operator turns the vehicle left relative to the traveling direction, the operator tilts the lever 2B from the neutral position to the left. When the operator turns the vehicle right relative to the traveling direction, the operator tilts the lever 2B from the neutral position to the right. When the operating force applied to the lever 2B is released, the lever 2B automatically returns to its original neutral position.

[0029] The steering unit 2 has a tilt angle sensor 2C. The tilt angle sensor 2C detects the tilt angle θ of the lever 2B. lr The tilt angle sensor 2C detects the tilt angle θ of the lever 2B. lr An electrical signal is generated according to the tilt angle θ lr is the tilt angle with respect to the neutral position of the lever 2B, and indicates the amount of operation of the lever 2B. When the lever 2B is tilted to the right with respect to the neutral position, the tilt angle θ lr When the lever 2B is tilted to the left from the neutral position, the tilt angle θ lr However, the correspondence between the tilting direction of the lever 2B and the positive and negative signs may be reversed.

[0030] The steering unit 2 is connected to the control device 4 via a harness, which is, for example, an electric wire. The tilt angle θ detected by the tilt angle sensor 2C lr is transmitted to the control device 4 via, for example, a harness. Incidentally, the steering unit 2 transmits the tilt angle θ lr may be transmitted to the control device 4. In this case, a communication circuit is provided in the steering unit 2 and the control device 4. The communication circuit includes a transmitting circuit that transmits a wireless signal and a receiving circuit that receives the wireless signal.

[0031] The steering unit 3 has a pinion shaft 21, a steering shaft 22, and a housing 23. The housing 23 rotatably supports the pinion shaft 21. The housing 23 also accommodates the steering shaft 22 so that it can reciprocate. The pinion shaft 21 is arranged to intersect with the steering shaft 22. Pinion teeth 21a of the pinion shaft 21 mesh with rack teeth 22a of the steering shaft 22. Tie rods 25 are connected to both ends of the steering shaft 22 via rack ends 24 made up of ball joints. The ends of the tie rods 25 are connected to knuckles (not shown) to which the steered wheels 5 are assembled.

[0032] The steering unit 3 comprises a steering motor 31, a transmission mechanism 32, and a conversion mechanism 33. The steering motor 31 is a source of the steering force applied to the steering shaft 22. The steering force is a force for steering the steered wheels 5. The steering motor 31 is, for example, a three-phase brushless motor. The transmission mechanism 32 is, for example, a belt transmission mechanism. The transmission mechanism 32 transmits the rotation of the steering motor 31 to the conversion mechanism 33. The conversion mechanism 33 is, for example, a ball screw mechanism. The conversion mechanism 33 converts the rotation transmitted via the transmission mechanism 32 into axial movement of the steering shaft 22.

[0033] The steered shaft 22 moves in the axial direction, and the steered angle θ of the steered wheels 5 w is changed. Pinion teeth 21a of pinion shaft 21 mesh with rack teeth 22a of steered shaft 22. Therefore, pinion shaft 21 rotates in conjunction with the movement of steered shaft 22. Pinion shaft 21 is a shaft that rotates in conjunction with the steering operation of steered wheels 5. The steered wheels 5 are steered left or right relative to the traveling direction of the vehicle, based on a neutral position corresponding to the straight-ahead state of the vehicle. The steering angle θ w The sign of is, for example, negative in the left steering direction with respect to the neutral position, and positive in the right steering direction.

[0034] The control device 4 controls the operation of the steering motor 31. The control device 4 has a processing circuit including any one of the following three components A1, A2, A3. A1. One or more processors that operate according to a computer program, which is software. The processor includes a CPU (Central Processing Unit) and memory.

[0035] A2. One or more dedicated hardware circuits, such as an application specific integrated circuit (ASIC), that perform at least some of the processing. The ASIC includes a CPU and memory.

[0036] A3. A hardware circuit that combines configurations A1 and A2. The memory is a computer-readable medium that stores a program that describes processes or instructions for the computer. In this embodiment, the computer is a CPU. The memory includes RAM (Random Access Memory) and ROM (Read Only Memory). The CPU executes the program stored in the memory at a predetermined calculation cycle to perform various controls.

[0037] Control device 4 receives the detection results of sensors mounted on the vehicle. The sensors include a vehicle speed sensor 41, a rotation angle sensor 42, and a yaw rate sensor 43. Vehicle speed sensor 41 detects vehicle speed V. Rotation angle sensor 42 is provided on steering motor 31. Rotation angle sensor 42 detects a rotation angle θ of steering motor 31. b Yaw rate sensor 43 detects the yaw rate of the vehicle. Control device 4 controls the operation of steering motor 31 based on the operation state of steering unit 2 and the detection results of various sensors. Control device 4 controls the supply of power to steering motor 31 so that steered wheels 5 are steered in accordance with the operation state of steering unit 2.

[0038] When lever 2B is in the neutral position, control device 4 controls steering motor 31 so that steered wheels 5 are maintained in a neutral steering position. The neutral steering position is the position of steered wheels 5 that corresponds to the vehicle traveling straight ahead. When lever 2B is tilted to the left with respect to the neutral position, control device 4 controls steering motor 31 so that steered wheels 5 are steered to the left with respect to the traveling direction of the vehicle. When lever 2B is tilted to the right with respect to the neutral position, control device 4 controls steering motor 31 so that steered wheels 5 are steered to the right with respect to the traveling direction of the vehicle.

[0039] When the lever 2B is tilted left or right with respect to the neutral position, the control device 4 detects the tilt angle θ lr The control device 4 controls the steering motor 31 so that a steering angle according to the steering angle θ is realized. Furthermore, when the lever 2B is tilted left or right with respect to the neutral position, the control device 4 controls the steering motor 31 so that the steered wheels 5 are turned at a predetermined steering angular velocity. The steering angular velocity is determined by the steering angle θ w is the time rate of change of

[0040] The control device 4 controls the operation of the notification device 6 installed in the vehicle. The notification device 6 may include a display device that notifies the driver visually, an alarm device that notifies the driver auditorily, or a haptic device that notifies the driver physically. The display device includes a HUD (Head Up Display), an instrument panel, a navigation system display, and an LED (Light Emitting Diode). The alarm device includes a speaker or a buzzer. The haptic device includes a vibration device that vibrates vehicle accessories that come into contact with the driver, such as a seat. The control device 4 generates a notification control signal S3 for the notification device 6.

[0041] <Configuration of control device 4> Next, the configuration of the control device 4 will be described. As shown in FIG. 2, the control device 4 includes a pinion angle calculation unit 61, a target pinion angle calculation unit 62, a pinion angle feedback control unit 63, a current supply control unit 64, and a notification control unit 65.

[0042] The pinion angle calculation unit 61 calculates the rotation angle θ of the steering motor 31 detected through the rotation angle sensor 42. b Based on this, the pinion angle θ p Calculate the pinion angle θ p is the rotation angle of pinion shaft 21. Steering motor 31 and pinion shaft 21 are linked via transmission mechanism 32, conversion mechanism 33, and steering shaft 22. Therefore, the rotation angle θ of steering motor 31 b and pinion angle θ p By utilizing this correlation, the rotation angle θ of the steering motor 31 is b From pinion angle θ p The pinion shaft 21 is engaged with the steering shaft 22. Therefore, the pinion angle θ p There is also a correlation between the pinion angle θ and the amount of movement of the steering shaft 22. p is the steering angle θ of the steered wheels 5 w The rotation angle sensor 42 detects the pinion angle θ p It is also a sensor for detecting

[0043] The target pinion angle calculation unit 62 calculates the target pinion angle θ in accordance with the operation state of the steering unit 2 and the running state of the vehicle. p * Calculate the target pinion angle θ p * is the pinion angle θ p The target pinion angle calculation unit 62 calculates the inclination angle θ of the lever 2B detected by the inclination angle sensor 2C. lr , and the vehicle speed V detected by the vehicle speed sensor 41. The target pinion angle calculation unit 62 calculates the inclination angle θ of the lever 2B. lr , and vehicle speed V are used to calculate the target pinion angle θ p * Calculate the target pinion angle θ p * corresponds to the target rotation angle of the shaft that rotates in conjunction with the steering operation of the steered wheels 5.

[0044] 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 pinion angle θ calculated by the pinion angle calculation unit 61 p The pinion angle feedback control unit 63 receives the pinion angle θ p is the target pinion angle θ p * The pinion angle θ p Through the feedback control of the steering torque command value T p * Calculate the steering torque command value T p * is the target value of the steering force.

[0045] The power supply control unit 64 controls the steering torque command value T p * Specifically, the power supply control unit 64 supplies the steering motor 31 with electric power according to the steering torque command value T p * The current control unit 64 calculates a current command value for the steering motor 31 based on the current I generated in the power supply path through a current sensor 66 provided in the power supply path for the steering motor 31. b Detect the value of the current I b The value of is the value of the current supplied to the steering motor 31. The current control unit 64 calculates the current command value and the current I b The deviation from the value of the steering torque command value T is calculated and the power supply to the steering motor 31 is controlled so as to eliminate the deviation. p * A torque corresponding to the

[0046] The notification control unit 65 controls the operation of the notification device 6. The notification control unit 65 generates a notification control signal S3 which is a command to cause the notification device 6 to perform various notification operations. The notification device 6 performs various notification operations based on the notification control signal S3.

[0047] The notification control unit 65 notifies the target pinion angle θ calculated by the target pinion angle calculation unit 62. p *, and the pinion angle θ calculated by the pinion angle calculation unit 61 p The notification control unit 65 receives the target pinion angle θ p * Or pinion angle θ p The notification control unit 65 may have a function to predict the course of the vehicle. In this case, the notification control unit 65 may display, for example, the steering state of the steered wheels 5 on a display device based on the vehicle speed V and the pinion angle θ p The notification control unit 65 predicts the course of the vehicle based on the above and displays the predicted course on the display device. w When the value of the vehicle speed becomes too large, the notification control unit 65 notifies the driver of this fact through the notification device 6. The notification control unit 65, for example, causes a display device to display a warning. The notification control unit 65, for example, causes an alarm device to generate an alarm sound. The notification control unit 65, for example, causes a sensation generating device to generate vibration.

[0048] <Target pinion angle calculation procedure> Next, the target pinion angle θ p * The procedure of the calculation process will be described with reference to the flowchart in Fig. 3. The process of the flowchart is executed at a predetermined calculation cycle.

[0049] As shown in the flowchart of FIG. 3, the control device 4 controls the tilt angle θ of the lever 2B detected by the tilt angle sensor 2C. lr (Step S101). lr is the electrical signal generated by the tilt angle sensor 2C.

[0050] Next, the control device 4 reads the inclination angle θ lr (Step S102). The filtering is performed using, for example, a first-order lag filter, and is a smoothing process for the electrical signal generated by the tilt angle sensor 2C. lris smoothed through filtering. For example, it is assumed that the lever 2B vibrates due to minute vibrations caused by the vehicle traveling. Through filtering, the tilt angle θ lr The minute change in position caused by vibration is a change in the position of the lever 2B that is not intended by the operator.

[0051] Next, the control device 4 calculates the target pinion angle θ p * (Step S103). The control device 4 calculates the target pinion angle θ p * Calculate the following. As shown in the graph of FIG. 4, the first map M1 is a graph showing the relationship between the tilt angle θ of the lever 2B and the tilt angle θ of the lever 2B. lr and the target pinion angle θ p * The first map M1 has the following characteristics: lr The larger the absolute value of the target pinion angle θ p * The absolute value of the target pinion angle θ becomes larger. p * The absolute value of the inclination angle θ lr It changes linearly with the change in the absolute value of

[0052] Next, the control device 4 reads the vehicle speed V (step S104), and calculates the first gain G1 based on the read vehicle speed V (step S105). The control device 4 calculates the first gain G1 using the second map M2. The first gain G1 is calculated based on the target pinion angle θ p * The second map M2 is set based on the viewpoint of making the value of the yaw rate gain constant regardless of the vehicle speed V. The yaw rate gain is calculated based on the inclination angle θ of the lever 2B. lr For example, the smaller the tilt angle θ lrThe value of the yaw rate gain increases as the direction of the steered wheels 5 is changed. The yaw rate gain is a value that reflects the vehicle response to the operation of the lever 2B.

[0053] As shown in the graph of FIG. 5, the second map M2 is a two-dimensional map that defines the relationship between the vehicle speed V and the first gain G1. The second map M2 has the following characteristics. That is, when the value of the vehicle speed V is less than the first vehicle speed threshold V1, the value of the first gain G1 is equal to the maximum value G 11 The maximum value G 11 is, for example, "1.0." After the value of the vehicle speed V reaches the first vehicle speed threshold V1, as the value of the vehicle speed V increases, the value of the first gain G1 decreases to the minimum value G1. 12 However, as the value of the vehicle speed V increases, the slope, which is the rate of change of the first gain G1 relative to the vehicle speed V, gradually decreases. After the value of the vehicle speed V reaches the second vehicle speed threshold V2, the value of the first gain G1 decreases to the minimum value G1. 12 is maintained.

[0054] Next, the control device 4 calculates the final target pinion angle θ p * The control device 4 calculates the target pinion angle θ calculated in step S103 as shown in the following equation (1) (step S106). p * is multiplied by the first gain G1 calculated in step S105 to obtain the final target pinion angle θ p * Calculate the following.

[0055] θ p(n) * =θ p * G1…(1) However, "θ p(n) * The subscript "(n)" in "(n)" is a natural number and represents the final target pinion angle θ p * indicates the current value of "·".

[0056] Next, the control device 4 calculates the final target pinion angle θ p * (Step S107). The filtering is performed using, for example, a first-order lag filter. p * is smoothed through filtering. By filtering, for example, the final target pinion angle θ p * The discontinuous changes in the vehicle speed are smoothed. Furthermore, the filtering process removes frequency components that are faster than the vehicle response required for normal driving, for example.

[0057] The above gives the target pinion angle θ p * The calculation process is completed. The control device 4 may perform a filter process on the first gain G1 calculated in the previous step S105. The filter process is, for example, a process using a first-order lag filter. The first gain G1 is smoothed through the filter process.

[0058] <Notification method> Next, an example of a notification mode through the notification device 6 will be described. As shown in FIG. 6, the control device 4 may notify the steering state of the steered wheels 5 through the notification device 6. The control device 4 displays, for example, a bar indicator 81 on the screen of the display device. The control device 4 notifies the steering state of the steered wheels 5 visually through the bar indicator 81. The bar indicator 81 extends, for example, in the left-right direction as seen by a driver seated in the driver's seat. The bar indicator 81 is divided into a plurality of display areas. The central display area 81A corresponds to the neutral position of the steered wheels 5. The leftmost display area 81B corresponds to the physical limit position of the steered wheels 5 when steered to the left. The rightmost display area 81C corresponds to the physical limit position of the steered wheels 5 when steered to the right. The control device 4 determines the target pinion angle θ p * Or pinion angle θ pThe amount of steering of the steered wheels 5 is recognized based on the display area 81A, and each display area is lit up in accordance with the amount of steering. Each display area is lit up one by one in order to the left or right according to the amount of steering of the steered wheels 5, with the central display area 81A as the reference. The bar indicator 81 does not have to be realized by software on the screen of the display device, but may be a display device as hardware.

[0059] As shown in Fig. 7(a), the control device 4 may notify the direction of the steered wheels 5 through the notification device 6. The control device 4 displays, for example, two virtual lanes 82A and virtual steered wheels 82B on the screen of the display device. The control device 4 determines the target pinion angle θ p * Or pinion angle θ p The amount of steering of the steered wheels 5 is recognized based on the above, and the direction of the virtual steered wheels 82B is changed in accordance with the amount of steering.

[0060] As shown in FIG. 7(b), the control device 4 may notify the direction of the steered wheels 5 through the notification device 6. The control device 4 displays, for example, a virtual steering wheel 82C on the screen of the display device. The control device 4 notifies the direction of the steered wheels 5 through the notification device 6. The control device 4 notifies the direction of the steered wheels 5 through the target pinion angle θ p * Or pinion angle θ p The amount of steering of the steered wheels 5 is recognized based on the rotational position of the virtual steering wheel 82C, and the rotational position of the virtual steering wheel 82C is changed according to the amount of steering. The direction of the steered wheels 5 can be recognized from the rotational position of the virtual steering wheel 82C.

[0061] 8, if the control device 4 has a function of predicting the vehicle's course, the control device 4 may notify the predicted course of the vehicle through the notification device 6. The control device 4 may, for example, p The path of the vehicle is predicted based on the above, and the predicted path 83 is displayed on a display device. The display device may be a HUD (Head-Up Display). The HUD is a display that displays an image on the front window of the vehicle, for example.

[0062] <Advantages of the First Embodiment> According to the first embodiment, it is possible to suppress changes in vehicle behavior due to unintended operation of the lever 2B while maintaining the ability of the vehicle behavior to follow the operation of the lever 2B. Specifically, this is as follows.

[0063] (1-1) Steering angle θ in response to operation of lever 2B w The sensitivity of the steering angle θ w The sensitivity of lever 2B is higher than that of lever 2B. Therefore, vehicle behavior may change sensitively in response to minute operations of lever 2B. Furthermore, lever 2B may unintentionally change its position slightly due to the influence of vehicle behavior. The influence of vehicle behavior includes, for example, changes in vehicle behavior due to the influence of lateral acceleration and roll. Lateral acceleration is the acceleration in a direction perpendicular to the vertical plane in the fore-and-aft direction of the vehicle when the vehicle turns. Roll is the force that rotates or tilts the vehicle body left and right around an axis that passes through the center of gravity of the vehicle from front to back.

[0064] Therefore, the control device 4 detects the tilt angle θ of the lever 2B detected by the tilt angle sensor 2C. lr The filtering process is performed on the inclination angle θ lr The filter processing is a smoothing process for the inclination angle θ lr Therefore, the position change of the lever 2B unintentionally by the operator is prevented from changing the target pinion angle θ p * That is, the inclination angle θ according to the operation of the lever 2B by the operator can be suppressed. lr is the target pinion angle θ p * Therefore, the steered wheels 5 are steered as intended by the operator. Also, it is possible to suppress the occurrence of unstable vehicle behavior caused by minute position changes accompanying vibration of the lever 2B.

[0065] (1-2) The control device 4 executes the following process to make the vehicle response to the operation of the lever 2B, i.e., the yaw rate gain, constant regardless of the vehicle speed V. That is, the control device 4 executes the following process to make the vehicle response to the operation of the lever 2B, i.e., the yaw rate gain, constant regardless of the vehicle speed V. lr The target pinion angle θ is calculated based on p * is multiplied by the first gain G1 to obtain the final target pinion angle θ p * That is, the target pinion angle θ is calculated according to the vehicle speed V. p * , and thus the steering angle θ w The processing in steps S105 and S106 is performed based on the steering angle θ of the steered wheels 5. w This is a process for adjusting the

[0066] The first gain G1 is set to a smaller value as the vehicle speed V increases. For example, when the vehicle speed V is in the low speed range, the tilt angle θ of the lever 2B is lr steering angle θ w The value of the first gain G1 is set so that the value of the ratio of the inclination angle θ of the lever 2B becomes larger when the vehicle speed V is in the medium speed range or the high speed range. lr steering angle θ w The value of the first gain G1 is set so that the value of the ratio is smaller.

[0067] This makes it possible to maintain a substantially constant yaw rate gain value in response to the operation of lever 2B across the entire vehicle speed range, from low to high. Furthermore, it is possible to maintain a substantially constant change in vehicle behavior in response to the operation of lever 2B. This improves vehicle running stability, particularly in the medium and high speed ranges. It is also possible to suppress excessive changes in vehicle behavior in response to the operation of lever 2B, while still ensuring the required vehicle responsiveness.

[0068] The low speed range is, for example, a speed range of "0 km / h or more and less than 40 km / h." The medium speed range is, for example, a speed range of "40 km / h or more and less than 60 km / h." The high speed range is, for example, a speed range of "60 km / h or more."

[0069] (1-3) The control device 4 determines the final target pinion angle θ p * By the filtering process, for example, the final target pinion angle θ p * The discontinuous changes in the vehicle speed are smoothed. Furthermore, the filtering process removes, for example, frequency components faster than the vehicle response required for normal driving. This allows the steered wheels 5 to be steered more smoothly and appropriately.

[0070] (1-4) The control device 4 adjusts the target pinion angle θ of the pinion shaft 21 in accordance with the amount of operation of the lever 2B. p * The control device 4 calculates the target pinion angle θ p * The steering motor 31 is controlled so that the actual angle of the pinion shaft 21 follows the pinion angle θ p By controlling the steering angle θ of the steered wheels 5 w can be controlled.

[0071] (1-5) The control device 4 executes processing for visually informing the driver of the steered state of the steered wheels 5. This processing includes display control for causing the notification device 6 to display the display contents shown in Figs. 6 to 8. This allows the driver of the vehicle to visually recognize the steered state of the steered wheels 5. Furthermore, maneuverability can be improved.

[0072] <Second embodiment> Next, a second embodiment of the steering device will be described. This embodiment basically has the same configuration as the first embodiment shown in Figs. 1 to 8. Therefore, detailed descriptions of the same members and configurations as those in the first embodiment will be omitted. This embodiment differs from the first embodiment in the tilting direction of the lever 2B, the configuration of the control device 4, and the target pinion angle θ p * This embodiment differs from the first embodiment in the calculation procedure.

[0073] The lever 2B can be tilted not only left and right but also forward and backward relative to the traveling direction of the vehicle. Furthermore, the lever 2B can also be tilted left or right while tilted forward or backward relative to the traveling direction of the vehicle.

[0074] The tilt angle sensor 2C detects the tilt angle θ of the lever 2B in the left-right direction. lr The tilt angle sensor 2C detects the tilt angle θ of the lever 2B in the front-rear direction. fb Detect the tilt angle θ fb is the tilt angle based on the neutral position of the lever 2B. When the lever 2B is tilted forward from the neutral position, the tilt angle θ fb When the lever 2B is tilted backward from the neutral position, the tilt angle θ fb However, the correspondence between the tilting direction of the lever 2B and the positive and negative signs may be reversed.

[0075] 12, the control device 4 includes a correction processing unit 70. The correction processing unit 70 corrects the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * Correction processing is performed on the

[0076] The correction processing unit 70 calculates the vehicle speed V detected by the vehicle speed sensor 41, the target pinion angle θ calculated by the target pinion angle calculation unit 62, and p * , and the yaw rate YR detected through the yaw rate sensor 43. The correction processing section 70 has a target yaw rate calculation section 71, a subtractor 72, a feedback control section 73, and an adder 74.

[0077] The target yaw rate calculation unit 71 calculates the target pinion angle θ p * and the target yaw rate YR based on the vehicle speed V. * Calculate the target yaw rate YR * is the target value of the yaw rate YR. The subtractor 72 calculates the target yaw rate YR *The yaw rate deviation ΔYR is calculated by subtracting the yaw rate YR from

[0078] The feedback control unit 73 converts the yaw rate YR detected by the yaw rate sensor 43 into a target yaw rate YR * Through the execution of feedback control to follow the target pinion angle θ p * Correction amount θ for pc The feedback control unit 73 calculates the correction amount θ by performing proportional calculation, integral calculation, and differential calculation on the yaw rate deviation ΔYR calculated by the subtractor 72. pc That is, the correction amount θ pc is the sum of the output value of the proportional element, the output value of the integral element, and the output value of the derivative element, which have the yaw rate deviation ΔYR as an input.

[0079] The adder 74 calculates the correction amount θ pc is calculated by the target pinion angle calculation unit 62. p * By adding this to the final target pinion angle θ p * Calculate the following.

[0080] The pinion angle feedback control unit 63 calculates the final target pinion angle θ p * The actual pinion angle θ p By performing feedback control to follow the pc The steering angle θ reflected w is realized.

[0081] <Target pinion angle calculation procedure> Next, the target pinion angle θ p * The procedure of this calculation process will be described with reference to the flowchart in Fig. 9. The process of the flowchart is executed at a predetermined calculation cycle.

[0082] As shown in the flowchart of FIG. 9, the control device 4 controls the lever 2B to move in the left-right direction based on the tilt angle θ lr and the longitudinal tilt angle θ fb (Step S201). lr ,θ fb is the electrical signal generated by the tilt angle sensor 2C.

[0083] Next, the control device 4 calculates the second gain G2 (step S202). The control device 4 calculates the second gain G2 using the third map M3. The second gain G2 is calculated based on the left-right tilt angle θ lr This is because, when the lever 2B can be tilted forward, backward, left, and right, the operator may unconsciously operate the lever 2B in the left-right direction while tilting the lever 2B forward or backward. For example, the operator may intend to tilt the lever 2B to the left, but the lever 2B may actually be tilted diagonally forward to the left. In this case, the amount of operation of the lever 2B in the left direction may differ from the amount of operation intended by the operator by the amount of forward operation of the lever 2B. For this reason, it is preferable to adjust the amount of operation of the lever 2B in the left-right direction according to the amount of operation of the lever 2B in the forward and backward directions. The same applies when the lever 2B is operated diagonally forward to the right, diagonally backward to the left, or diagonally backward to the right.

[0084] As shown in the graph of FIG. 10, the third map M3 is fb The third map M3 is a two-dimensional map that defines the relationship between the inclination angle θ and the second gain G2. fb When is a positive value, the tilt angle θ fb As the absolute value of the tilt angle θ increases, the value of the second gain G2 increases. fb When is negative, the tilt angle θ fb As the absolute value of increases, the value of the second gain G2 decreases. fb It changes linearly with the change in the inclination angle θ fbWhen the value of is "0", the value of the second gain G2 is "1". The second gain G2 is a positive value.

[0085] Depending on the product specifications, the characteristics of the third map M3 may be changed as follows. As shown by the dashed line in the graph of Figure 10, the tilt angle θ fb If is a positive value, the tilt angle θ fb is the threshold value θ th When the value is less than fb Regardless of the value of , the value of the second gain G2 is set to "1." fb If is a positive value, the tilt angle θ fb is the threshold value θ th When the value is equal to or greater than 1, the value of the second gain G2 is set to a value G 21 The tilt angle in the front-rear direction is set to θ fb If is a negative value, the tilt angle θ fb Regardless of the value of , the value of the second gain G2 is set to "1".

[0086] Next, the control device 4 determines the final tilt angle θ of the lever 2B. lr (Step S203). The control device 4 calculates the left-right tilt angle θ read in step S201 as shown in the following equation (2). lr is multiplied by the second gain G2 calculated in step S201, the final tilt angle θ of the lever 2B is lr Calculate the following.

[0087] θ lr(n) =θ lr G2…(2) However, "θ lr(n) The subscript "(n)" in "(n)" is a natural number, and the final tilt angle θ of the lever 2B lr indicates the current value of "·".

[0088] Next, the control device 4 calculates the tilt angle θ of the lever 2B calculated in step S203. lr(Step S204). The filtering process is performed using, for example, a first-order lag filter. The final tilt angle θ of the lever 2B lr , which is smoothed through filtering.

[0089] Next, the control device 4 calculates the target pinion angle θ p * (Step S205). The control device 4 calculates the target pinion angle θ using the first map M1 shown in the graph of FIG. p * Calculate the following.

[0090] Next, the control device 4 reads the vehicle speed V (step S206), and calculates the first gain G1 based on the read vehicle speed V (step S207). The control device 4 calculates the first gain G1 using the second map M2 shown in FIG.

[0091] Next, the control device 4 calculates the final target pinion angle θ p * The control device 4 calculates the target pinion angle θ calculated in step S205 as shown in the above formula (1) (step S208). p * is multiplied by the first gain G1 calculated in step S207 to obtain the final target pinion angle θ p * Calculate the following.

[0092] Next, the control device 4 calculates the final target pinion angle θ p * (Step S209). The filtering is performed using, for example, a first-order lag filter. p * is smoothed through filtering.

[0093] Next, the control device 4 executes a process for limiting the steering angular velocity (step S210). The control device 4 sets a limit value ωth The pinion angular velocity is calculated by the pinion angle θ p The pinion angular velocity is, for example, a time change rate of the pinion angle θ calculated by the pinion angle calculation unit 61. p The control device 4 uses the fourth map M4 to determine the limit value ω th Calculate the following.

[0094] As shown in the graph of FIG. 11, the fourth map M4 is a map of the vehicle speed V and the limit value ω th The fourth map M4 has the following characteristics: when the value of the vehicle speed V is less than the third vehicle speed threshold V3, the limit value ω th The absolute value of the limit value ω is maintained at a maximum value ω1. The maximum value ω1 is, for example, 360 deg / s. After the value of the vehicle speed V reaches the third vehicle speed threshold V3, the limit value ω is increased as the value of the vehicle speed V increases. th The absolute value of gradually decreases towards the minimum value ω2. However, the limit value ω th The absolute value of the limit value ω changes linearly with the change in the vehicle speed V. After the value of the vehicle speed V reaches the fourth vehicle speed threshold V4, th The absolute value of is maintained at a minimum value ω2.

[0095] The control device 4 determines the limit value ω th The control device 4 compares the absolute value of the actual pinion angular velocity with the absolute value of the limit value ω th If the absolute value of the actual pinion angular velocity is greater than the absolute value of the limit value ω, the control device 4 executes a process of limiting the absolute value of the pinion angular velocity. th The control device 4 controls the steering motor 31 so that the absolute value of the actual pinion angular velocity is equal to or less than the limit value ω th If the absolute value of the pinion angular velocity is less than the absolute value of the pinion angular velocity, the process of limiting the absolute value of the pinion angular velocity is not executed.

[0096] Next, the control device 4 calculates the target pinion angle θ p *The control device 4 executes the correction process for the target pinion angle θ calculated in the previous step S208. p * and a target yaw rate YR based on the vehicle speed V detected by the vehicle speed sensor 41. * The control device 4 calculates the yaw rate YR detected by the yaw rate sensor 43 as the target yaw rate YR. * Through the execution of feedback control to follow the target pinion angle θ p * Correction amount θ for pc The control device 4 calculates the target pinion angle θ p * The correction amount θ pc By reflecting this, the target pinion angle θ p * Correct the following.

[0097] The above gives the target pinion angle θ p * The calculation process is completed. <Advantages of the second embodiment> The second embodiment has the following advantages in addition to the advantages of the first embodiment described above in (1-1) to (1-5).

[0098] (2-1) The lever 2B can be tilted in four directions: forward, backward, left, and right. In this case, the operator may unconsciously operate the lever 2B left or right while tilting the lever 2B forward or backward. As a result, the amount of operation of the lever 2B in the direction intended by the operator may differ from the actual amount of operation intended by the operator.

[0099] Therefore, the control device 4 determines the tilt angle θ of the lever 2B in the front-rear direction. fb Depending on the angle of inclination θ lr This process includes steps S202 and S203. Front-to-rear tilt angle θ fb The second gain G2 calculated in accordance with the left-right tilt angle θ lr By multiplying this, the left-right tilt angle θlr This correction process corrects the value of the left-right tilt angle θ lr The value of the inclination angle θ lr Therefore, the operator can steer the vehicle as intended.

[0100] (2-2) The control device 4 executes a process for limiting the steering angular velocity in accordance with the vehicle speed V. This process includes the process of step S210. By this limiting process, the pinion angular velocity is limited to a limit value ω th The limit value ω th The absolute value of is set to a smaller value as the vehicle speed V increases. In other words, the steering angular velocity is limited to a smaller value as the vehicle speed V increases. Therefore, the steered wheels 5 can be steered at an appropriate steering angular velocity according to the vehicle speed V.

[0101] (2-3) The control device 4 calculates the target pinion angle θ p * Based on this, the target yaw rate YR * Calculate the target pinion angle θ p * is a vehicle state quantity that reflects the steering state of the steered wheels 5. Target yaw rate YR * is a target value of the yaw rate YR, which is a vehicle state quantity that reflects the turning state of the vehicle. * The steering angle θ of the steered wheels 5 is controlled by executing feedback control to make the actual value of the yaw rate YR follow the actual value of the yaw rate YR. w The correction amount θ to be reflected in pc The control device 4 calculates the correction amount θ pc The steering angle θ w This process is performed to reflect the target pinion angle θ calculated in step S208. p * The correction amount θ pc This includes adding the following.

[0102] This configuration maintains the turning state of the vehicle according to the steering state of the steered wheels 5. As a result, it is possible to suppress the occurrence of so-called vehicle drift, for example, when traveling on a canted road. A canted road is a linear slope that slopes in the vehicle width direction, perpendicular to the vehicle's direction of travel. Vehicle drift occurs when the vehicle is affected by the slope of the canted road and gradually descends toward the lower side of the canted road as the vehicle moves forward.

[0103] <Third embodiment> Next, a third embodiment of the steering device will be described. This embodiment basically has the same configuration as the first embodiment shown in Figs. 1 to 8. Therefore, detailed description of the same members and configurations as those in the first embodiment will be omitted. In this embodiment, the target pinion angle θ p * This embodiment differs from the first embodiment in the calculation procedure.

[0104] As shown in the flowchart of FIG. 13, the control device 4 controls the tilt angle θ of the lever 2B detected by the tilt angle sensor 2C. lr (Step S301). lr is the electrical signal generated by the tilt angle sensor 2C.

[0105] Next, the control device 4 calculates the target pinion angle θ p * (Step S103). The control device 4 calculates the target pinion angle θ using the fifth map M5. p * Calculate the following. As shown in the graph of FIG. 14, the fifth map M5 is a map showing the relationship between the tilt angle θ of the lever 2B and the tilt angle θ of the lever 2B. lr and the target pinion angle θ p * The fifth map M5 has the following characteristics: lr With respect to the change in the target pinion angle θ p * The absolute value of changes in a stepwise manner. The tilt angle θ of lever 2B lrThe absolute value of the determined update value Δθ lr For each increase in the target pinion angle θ p * The absolute value of the determined update value Δθ p * The updated value Δθ lr is the first update value. Update value Δθ p * is the second update value.

[0106] For example, the inclination angle θ of lever 2B lr The absolute value of the first tilt angle threshold θ th1 During the period until the target pinion angle θ p * The absolute value of is maintained at "0". lr The absolute value of the first tilt angle threshold θ th1 When the target pinion angle θ p * The absolute value of varies from "0" to the first value θ p1 The first tilt angle threshold θ th1 The updated value Δθ is smaller than "0". lr The first value θ is larger than the first value θ. p1 The updated value Δθ is smaller than "0". p * is a value larger by

[0107] Lever 2B inclination angle θ lr The absolute value of the first tilt angle threshold θ th1 After reaching the second tilt angle threshold θ th2 During the period until the target pinion angle θ p * The absolute value of the first value θ p1 The tilt angle θ lr The absolute value of the second tilt angle threshold θ th2 When the target pinion angle θ p * The absolute value of the first value θ p1 to the second value θ p2 The second tilt angle threshold θ th2 is the first tilt angle threshold θth1 than the updated value Δθ lr The second value θ is larger than the p2 is the first value θ p1 than the updated value Δθ p * is a value larger by

[0108] Thereafter, similarly, the inclination angle θ of the lever 2B lr The absolute value of the update value Δθ lr Each time the target pinion angle θ p * The absolute value of the update value Δθ p * increases by only The inclination angle θ of lever 2B lr When the absolute value of decreases, the inclination angle θ of the lever 2B lr This is the same as when the absolute value of the inclination angle θ of the lever 2B increases. lr The absolute value of the determined update value Δθ lr Each time the target pinion angle θ p * The absolute value of the determined update value Δθ p * decreases by

[0109] Next, the control device 4 calculates the target pinion angle θ p * It is determined whether or not has changed (step S303). The control device 4 determines the target pinion angle θ p * When it is determined that the target pinion angle θ has changed (YES in step S303), the target pinion angle θ calculated in step S302 is changed as shown in the following equation (3). p * and the pinion angle θ calculated by the pinion angle calculation unit 61. p The deviation Δθ between the two is calculated (step S304).

[0110] Δθ=θ p * -θ p …(3) Next, the control device 4 determines the pinion angular velocity (step S305). The control device 4 adjusts the pinion angle θ so that the deviation Δθ calculated in step S304 becomes "0" over a predetermined gradual change period ΔT. p The updated value θ p_ad Calculate the updated value θ p_ad is the pinion angle θ per unit time during the gradual change period ΔT p The control device 4 controls the pinion angle θ p The value of is updated every unit time θ p_ad The steering motor 31 is controlled so that the pinion angle θ p is interpolated so that the deviation Δθ becomes "0" over the gradual change period ΔT. The pinion angular velocity is calculated by p Therefore, the updated value θ p_ad * Determining this also determines the pinion angular velocity.

[0111] The control device 4 calculates the updated value θ using the following equation (4): p_ad Calculate the following. θ p_ad =Δθ / ΔT …(4) where "Δθ" is the target pinion angle θ p * and pinion angle θ p "ΔT" is the period of gradual change. " / " indicates division.

[0112] In the previous step S303, the control device 4 determines the target pinion angle θ p * When it is determined that the pinion angular velocity has not changed (NO in step S303), the pinion angular velocity is maintained (step S306), and the process ends.

[0113] <Changes in target pinion angle and pinion angle over time> Next, the target pinion angle θ p * and the actual pinion angle θ p An example of the change over time will be described below.

[0114] As shown in the graph of FIG. 15, the target pinion angle θ p * is changed from "0" corresponding to the vehicle traveling straight to the first target value θ1 (time t1), the pinion angle θ is gradually changed so that the first deviation Δθ1 becomes "0" over the gradual change period ΔT. p is interpolated. Pinion angle θ p The pinion angle θ gradually increases from time t1 toward the first target value θ1. p is "0" at time t1. Pinion angle θ p reaches the first target value θ1 at the timing when the gradual change period ΔT has elapsed, starting from time t1.

[0115] The first deviation Δθ1 is expressed by the following equation (5): p * is the same value as Δθ1=θ1-θ p …(5) However, "θ p " is the pinion angle, which is "0" here.

[0116] Next, the pinion angle θ p After reaching the first target value θ1, the target pinion angle θ p * When the pinion angle θ changes from the first target value θ1 to the second target value θ2 (time t2), the pinion angle θ is gradually changed so that the second deviation Δθ2 becomes "0" over the gradual change period ΔT. p The second target value θ2 is greater than the first target value θ1. p The pinion angle θ gradually increases from time t2 toward the second target value θ2. p is the same value as the first target value θ1 at time t2. p reaches the second target value θ2 at the timing when the gradual change period ΔT has elapsed, starting from time t2.

[0117] The second deviation Δθ2 is expressed by the following equation (6): p* is the same value as Δθ2=θ2-θ p …(6) However, "θ p " is the pinion angle, which is the same value as the first target value θ1 in this case.

[0118] Next, the pinion angle θ p After reaching the second target value θ2, the target pinion angle θ p * is changed from the second target value θ2 to the third target value θ3 (time t3), the pinion angle θ is gradually changed so that the third deviation Δθ3 becomes "0" over the gradual change period ΔT. p The third target value θ3 is greater than the second target value θ2. p The pinion angle θ gradually increases from time t3 toward the third target value θ3. p is the same as the second target value θ2 at time t3. p reaches the third target value θ3 at the timing when the gradual change period ΔT has elapsed, starting from time t3.

[0119] The third deviation Δθ3 is expressed by the following equation (7): p * is the same value as Δθ3=θ3-θ p …(7) However, "θ p " is the pinion angle, which is the same value as the second target value θ2 in this case.

[0120] Before the gradual change period ΔT has elapsed, the target pinion angle θ p * For example, starting from time t3, before the gradual change period ΔT has elapsed, the value of the target pinion angle θ p * When the third target value θ3 changes to the fourth target value θ4 (time t4), the fourth target value θ4 and the pinion angle θ pThe pinion angle θ is adjusted so that the fourth deviation Δθ4, which is the deviation from the p The fourth target value θ4 is greater than the third target value θ3. p The pinion angle θ3′ at time t4 is greater than the second target value θ2 and less than the fourth target value θ4. p reaches the fourth target value θ4 at the timing when the gradual change period ΔT has elapsed, starting from time t4.

[0121] The fourth deviation Δθ4 is expressed by the following equation (8): p * The fourth deviation Δθ4 is a value larger than the predetermined updated value Δθ p * is greater than.

[0122] Δθ4=θ4-θ3′ …(8) Target pinion angle θ p * Every time the value of changes, the pinion angle θ is adjusted so that the deviation Δθ at the time of the change becomes "0" over the gradual change period ΔT. p is interpolated.

[0123] Target pinion angle θ p * Even when the value of the target pinion angle θ p * The same is true when the value of increases. As shown in the graph in Figure 15, the pinion angle θ p After reaching the fourth target value θ4, the target pinion angle θ p * When the pinion angle θ changes from the fourth target value θ4 to the third target value θ3 (time t5), the fifth deviation Δθ5 is gradually changed to "0" over the gradual change period ΔT. pThe third target value θ3 is smaller than the fourth target value θ4. p The pinion angle θ gradually decreases toward the third target value θ3 starting from time t5. p is the same value as the fourth target value θ4 at time t5. p reaches the third target value θ3 at the timing when the gradual change period ΔT has elapsed, starting from time t5.

[0124] The fifth deviation Δθ5 is expressed by the following equation (9): The fifth deviation Δθ5 is calculated by the determined update value Δθ p * is the same value as Δθ5=θ3-θ p …(9) However, "θ p " is the pinion angle, which is the same value as the fourth target value θ4 in this case.

[0125] Next, the pinion angle θ p After reaching the third target value θ3, the target pinion angle θ p * When the pinion angle θ changes from the third target value θ3 to the second target value θ2 (time t6), the sixth deviation Δθ6 is gradually changed to "0" over the gradual change period ΔT. p The second target value θ2 is smaller than the third target value θ3. p The pinion angle θ gradually decreases toward the second target value θ2 starting from time t6. p is the same as the third target value θ3 at time t6. p reaches the second target value θ2 at the timing when the gradual change period ΔT has elapsed, starting from time t6.

[0126] The sixth deviation Δθ6 is expressed by the following equation (10): The sixth deviation Δθ6 is calculated by the determined update value Δθ p * is the same value as Δθ6=θ2-θ p …(10) However, "θ p" is the pinion angle, which is the same value as the third target value θ3 in this case.

[0127] Before the gradual change period ΔT has elapsed, the target pinion angle θ p * For example, starting from time t6, before the gradual change period ΔT has elapsed, the value of the target pinion angle θ p * When the second target value θ2 changes to the first target value θ1 (time t7), the fourth target value θ4 and the pinion angle θ p The pinion angle θ is adjusted so that the seventh deviation Δθ7, which is the deviation from the p is interpolated. The first target value θ1 is smaller than the second target value θ2. p The pinion angle θ2′ at time t7 is greater than the second target value θ2. p reaches the first target value θ1 at the timing when the gradual change period ΔT has elapsed, starting from time t7.

[0128] The seventh deviation Δθ7 is expressed by the following equation (11): The seventh deviation Δθ7 is calculated by the determined update value Δθ p * The seventh deviation Δθ7 is a value larger than the predetermined updated value Δθ p * is greater than.

[0129] Δθ7=θ1-θ2′ …(11) Target pinion angle θ p * Every time the value of changes, the pinion angle θ is adjusted so that the deviation Δθ at the time of the change becomes "0" over the gradual change period ΔT. p is interpolated.

[0130] <Advantages of the third embodiment> The third embodiment has the following advantages in addition to the advantages of the first embodiment described above in (1-5).

[0131] (3-1) Lever 2B inclination angle θ lr With respect to the change in the target pinion angle θ p * The absolute value of the inclination angle θ of the lever 2B changes stepwise. lr The absolute value of the determined update value Δθ lr For each increase in the target pinion angle θ p * The absolute value of the determined update value Δθ p * Also, the inclination angle θ of the lever 2B increases lr The absolute value of the determined update value Δθ lr Each time the target pinion angle θ p * The absolute value of the determined update value Δθ p * Therefore, the steering angle θ of the steered wheels 5 is reduced by a small amount in response to a slight operation of the lever 2B. w It is possible to suppress the excessive changes in the

[0132] (3-2) The control device 4 determines the target pinion angle θ p * When the value of changes, the target pinion angle θ p * and the actual pinion angle θ p The steering motor 31 is controlled so that the deviation Δθ between the pinion angle θ and the target pinion angle θ becomes "0" over a predetermined gradual change period ΔT. p is the target pinion angle θ p * The target pinion angle θ is set at the timing when the gradual change period ΔT has elapsed, based on the point when the value of p * Target pinion angle θ p * With respect to the change of pinion angle θ pchanges more smoothly. As a result, the steered wheels 5 can be steered more smoothly. Furthermore, even if the operator operates the lever 2B roughly, the steered wheels 5 are steered smoothly. As a result, changes in vehicle behavior that would disturb the operator's posture can be suppressed. Excessive changes in vehicle behavior in response to the operation of the lever 2B can be suppressed.

[0133] (3-3) Pinion angle θ p is the target pinion angle θ p * During the period when the pinion angle is changing toward the target pinion angle θ p * When the value of changes, the pinion angle θ p and target pinion angle θ p * The pinion angle θ is calculated from the deviation Δθ between the p The new updated value θ p_ad That is, the target pinion angle θ p * The pinion angle θ when the value of p and target pinion angle θ p * The pinion angle θ is adjusted so that the deviation Δθ from the p Therefore, an appropriate pinion angular velocity and therefore a steering angular velocity can be obtained depending on the situation at the time. w This can suppress hypersensitive changes in the

[0134] <Fourth embodiment> Next, a fourth embodiment of the steering device will be described. This embodiment basically has the same configuration as the third embodiment shown in Figs. 12 to 15. Therefore, detailed description of the same members and configuration as the third embodiment will be omitted. This embodiment differs from the third embodiment in the method of setting the gradual change period ΔT.

[0135] The control device 4 changes the gradual change period ΔT in accordance with the vehicle speed V. The control device 4 calculates the gradual change period ΔT using a sixth map M6. As shown in the graph of Fig. 16, the sixth map M6 is a two-dimensional map that defines the relationship between the vehicle speed V and the gradual-change period ΔT. The sixth map M6 has the following characteristics. That is, the faster the vehicle speed V, the longer the gradual-change period ΔT. The gradual-change period ΔT changes linearly with changes in the vehicle speed V.

[0136] <Advantages of the Fourth Embodiment> The fourth embodiment has the following advantages in addition to the advantages of the third embodiment described above in (3-1) to (3-3).

[0137] (4-1) The control device 4 adjusts the gradual-change period ΔT in accordance with the vehicle speed V. This allows the gradual-change period ΔT to be set to a more appropriate time in accordance with the vehicle speed V. For example, the faster the vehicle speed V, the longer the gradual-change period ΔT. When traveling at a vehicle speed V in the medium or high speed range, increases in the pinion angular velocity and therefore the steering angular velocity are suppressed, improving the vehicle's running stability. Furthermore, the slower the vehicle speed V, the shorter the gradual-change period ΔT. When traveling at a vehicle speed V in the low speed range, the pinion angular velocity and therefore the steering angular velocity become faster, ensuring responsiveness.

[0138] <Fifth embodiment> Next, a fifth embodiment of the steering device will be described. This embodiment basically has the same configuration as the first embodiment shown in Figs. 1 to 8. Therefore, detailed descriptions of the same members and configurations as those in the first embodiment will be omitted. This embodiment differs from the first embodiment in the tilting direction of the lever 2B, the configuration of the control device 4, and the target pinion angle θ p * This embodiment differs from the first embodiment in the calculation procedure.

[0139] The control device 4 executes the processes in the flowchart of FIG. 3 to calculate the target pinion angle θ p *However, in step S103, the control device 4 calculates the target pinion angle θ using the seventh map M7. p * Calculate the following.

[0140] As shown in the graph of FIG. 17, the seventh map M7 is lr and the target pinion angle θ p * The seventh map M7 has a first characteristic line LA that indicates the characteristics for a turning operation, and a second characteristic line LB that indicates the characteristics for a returning operation. p * The absolute value of the inclination angle θ of lever 2B lr It has a predetermined hysteresis characteristic with respect to the change of

[0141] The turning operation is performed by turning the steered wheels 5 at a steering angle θ w The return operation is an operation of the lever 2B to steer the steered wheels 5 in a direction to return them to the neutral position.

[0142] Neutral position of lever 2B (θ lr When the cutting operation is performed based on the inclination angle θ lr As the absolute value of increases from "0", the target pinion angle θ p * The absolute value of gradually increases. However, the inclination angle θ lr As the absolute value of increases, the gradient of the first characteristic line LA gradually increases. lr Target pinion angle θ with respect to the change in the absolute value of p * is the rate of change in the absolute value of

[0143] When the steering operation is subsequently performed, the target pinion angle θ p * The absolute value of the target pinion angle θp * The predetermined period begins from the start of the steering back operation and is maintained at the absolute value of the tilt angle θ lr reaches a value on the second characteristic line LB.

[0144] Inclination angle θ lr After the absolute value of reaches the value on the second characteristic line LB, the inclination angle θ lr As the absolute value of decreases, the target pinion angle θ p * The absolute value of gradually decreases. However, the inclination angle θ lr As the absolute value of β decreases, the slope of the second characteristic line LB gradually decreases. Also, the slope of the second characteristic line LB is generally greater than the slope of the first characteristic line LA.

[0145] If a steering operation is performed again while a steering return operation is being performed, the target pinion angle θ p * The absolute value of the target pinion angle θ p * The predetermined period begins from the start of the cutting operation and is maintained at the absolute value of the inclination angle θ lr The period until the absolute value of the inclination angle θ reaches the value on the first characteristic line LA. lr After the absolute value of reaches the value on the first characteristic line LA, the target pinion angle θ p * is calculated.

[0146] <Target pinion angle calculation procedure> Next, the target pinion angle θ p * The procedure of this calculation process will be described with reference to the flowchart in Fig. 18. The process of the flowchart is executed at a predetermined calculation cycle.

[0147] As shown in the flowchart of FIG. 18, the control device 4 controls the tilt angle θ of the lever 2B detected by the tilt angle sensor 2C. lr (Step S401). lris the electrical signal generated by the tilt angle sensor 2C.

[0148] Next, the control device 4 determines whether the state of the lever 2B is in the maintained steering state (step S402). When it is determined that the state of the lever 2B is in the maintained steering state (YES in step S402), the control device 4 adjusts the target pinion angle θ p * This time value θ p(n) * the target pinion angle θ p * The previous value of θ p(n-1) * (step S403), and the process ends.

[0149] In the previous step S402, when it is not determined that the state of the lever 2B is in the maintained steering state (NO in step S402), the control device 4 determines whether the tilt angle θ lr This time value θ lr(n) The absolute value of the inclination angle θ lr The previous value of θ lr(n-1) It is determined whether the absolute value of is greater than (step S404).

[0150] The control device 4 determines the inclination angle θ lr This time value θ lr(n) The absolute value of the inclination angle θ lr The previous value of θ lr(n-1) If it is determined that the absolute value of is greater than the absolute value of (YES in step S404), it is determined that a cutting operation is being performed, and the process proceeds to step S405.

[0151] In step S405, the control device 4 determines the inclination angle θ lr This time value θ lr(n) The target pinion angle θ obtained from the first characteristic line LA based on pa * and target pinion angle θ p * The previous value of θ p(n-1) * Compare with.

[0152] As shown in the graph of FIG. 19, the control device 4 calculates the target pinion angle θ obtained from the first characteristic line LA. pa * The value of the target pinion angle θ p * The previous value of θ p(n-1) * If the value is not equal to or greater than the above (NO in step S405), the process proceeds to the previous step S403.

[0153] The control device 4 calculates the target pinion angle θ obtained from the first characteristic line LA. pa * The value of the target pinion angle θ p * The previous value of θ p(n-1) * If the value is equal to or greater than the target pinion angle θ p * This time value θ p(n) * The target pinion angle θ obtained from the first characteristic line LA pa * (step S406), and the process ends.

[0154] In the previous step S404, the control device 4 calculates the inclination angle θ lr This time value θ lr(n) The absolute value of the inclination angle θ lr The previous value of θ lr(n-1) If it is not determined that the absolute value of is not greater than the absolute value of (NO in step S404), it is determined that a steering back operation is being performed, and the process proceeds to step S407.

[0155] In step S407, the control device 4 determines the inclination angle θ lr This time value θ lr(n) The target pinion angle θ obtained from the second characteristic line LB based on pb * and target pinion angle θ p * The previous value of θ p(n-1) * Compare with.

[0156] As shown in the graph of FIG. 20, the control device 4 calculates the target pinion angle θ obtained from the second characteristic line LB. pb * The value of the target pinion angle θ p * The previous value of θ p(n-1) * If the value is not the value below (NO in step S407), the process proceeds to the previous step S403.

[0157] The control device 4 calculates the target pinion angle θ obtained from the second characteristic line LB. pb * The value of the target pinion angle θ p * The previous value of θ p(n-1) * If the value is equal to or less than the above (YES in step S407), the target pinion angle θ p * This time value θ p(n) * The target pinion angle θ obtained from the second characteristic line LB pb * (step S408), and the process ends.

[0158] <Advantages of the Fifth Embodiment> The fifth embodiment has the following advantages in addition to the advantages of the first embodiment described above in (1-1) to (1-5).

[0159] (5-1) When a steering operation and a steering return operation are performed through the lever 2B, the control device 4 adjusts the θ lr The target pinion angle θ pb * The target pinion angle θ is set so that the absolute value of pb * For example, the control device 4 uses the seventh map M7 to calculate the target pinion angle θ pb * The seventh map M7 has a first characteristic line LA that indicates the characteristics for a steering operation, and a second characteristic line LB that indicates the characteristics for a steering return operation.

[0160] Therefore, depending on whether the operation state of the lever 2B is a turning operation state or a returning operation state, a more appropriate target pinion angle θ p * Therefore, the steered wheels 5 can be steered more appropriately according to the operating state of the lever 2B.

[0161] (5-2) When a steering return operation is performed while a steering operation is being performed, the target pinion angle θ p * The absolute value of the target pinion angle θ p * (NO in step S405→step S403). Also, if a steering operation is performed during a steering-back operation, the target pinion angle θ p * The absolute value of the target pinion angle θ p * (NO in step S407→step S403).

[0162] Therefore, when the steering wheel is turned forward or returned to its original position, a slight tilt angle θ lr This reduces changes in vehicle behavior caused by changes in the steering angle. This also improves the operability of lever 2B and driving comfort.

[0163] (5-3) As the amount of operation of the lever 2B decreases, the inclination angle θ lr Target pinion angle θ with respect to change p * As the amount of operation of the lever 2B increases, the rate of change of the inclination angle θ lr Target pinion angle θ with respect to change p * The rate of change is greater.

[0164] Therefore, the smaller the operation amount of the lever 2B, the smaller the steering angle θ wIn addition, the greater the amount of operation of the lever 2B, the slower the steering angle θ w Therefore, in the region where the operation amount of the lever 2B is small, the slight tilt angle θ lr In addition, in a region where the operation amount of the lever 2B is large, the change in the vehicle behavior caused by the change in the steering angle θ w This improves the responsiveness of the vehicle and also improves the maneuverability of the vehicle.

[0165] <Other embodiments> Each embodiment may be modified as follows. In the first and second embodiments, the first map M1 shown in FIG. 4 is a map of the inclination angle θ lr The target pinion angle θ p * The absolute value of may be set to change nonlinearly.

[0166] In the first and second embodiments, the second map M2 shown in FIG. 5 may be set so that the first gain G1 changes linearly with changes in the vehicle speed V. In the first and second embodiments, the first map M1 shown in Fig. 4 and the second map M2 shown in Fig. 5 may be integrated into a single map. The map is a two-input, one-output map, and the inclination angle θ of the lever 2B is lr and the target pinion angle θ based on the vehicle speed V. p * In this case, the input signal is the tilt angle θ of the lever 2B. lr and vehicle speed V, and target pinion angle θ as an output signal. p * In addition, the tilt angle θ of the lever 2B, which is an input signal, may be filtered. lr The vehicle speed V may be filtered, or the target pinion angle θ p * Alternatively, filtering may be performed only on the

[0167] In the second embodiment, the limiting process of the steering angular velocity executed in step S210 of FIG. 9 may be changed as follows: p * Alternatively, a vehicle state quantity that reflects the vehicle behavior may be estimated from the vehicle state quantity, and the estimated vehicle state quantity may be limited. The vehicle state quantity may include, for example, a yaw rate and a lateral acceleration. In this way, excessive vehicle behavior can also be suppressed.

[0168] In the third and fourth embodiments, the control device 4 reads the tilt angle θ lr In this way, it is possible to obtain the same effect as that described in (1-1) above.

[0169] In the third and fourth embodiments, the control device 4 may calculate the first gain G1 using the second map M2 shown in Fig. 5. The control device 4 may calculate the first gain G1 using the target pinion angle θ calculated in step S302 of the flowchart in Fig. 13. p * By multiplying the first gain G1 by the final target pinion angle θ p * In this way, the same effect as that described in (1-2) above can be obtained.

[0170] In the third and fourth embodiments, the characteristics of the fifth map M5 may be changed as appropriate. For example, when the tilt angle θ of the lever 2B is lr Update value Δθ for lr may be set to different values ​​depending on the amount of operation of the lever 2B. For example, the inclination angle θ lr The updated value Δθ in the region where the value of lr The inclination angle θ lr The updated value Δθ in the region with a larger value lr In addition, the target pinion angle θ p * Update value Δθ for p *The value may be set appropriately depending on the product specifications.

[0171] In the fourth embodiment, the sixth map M6 shown in FIG. 16 may be set so that the gradual-change period ΔT changes nonlinearly with changes in the vehicle speed V. In the fifth embodiment, the control device 4 reads the tilt angle θ lr In this way, it is possible to obtain the same effect as that described in (1-1) above.

[0172] In the fifth embodiment, the control device 4 may calculate the first gain G1 by using the second map M2 shown in Fig. 5. The control device 4 may calculate the first gain G1 by using the target pinion angle θ calculated in step S403, step S406, or step S408 of the flowchart in Fig. 18. p * By multiplying the first gain G1 by the final target pinion angle θ p * In this way, the same effect as that described in (1-2) above can be obtained.

[0173] In the fifth embodiment, the seventh map M7 shown in Fig. 17 may be modified as follows: For example, the first characteristic line LA and the second characteristic line LB are determined based on the inclination angle θ of the lever 2B. lr Change in target pinion angle θ p * may be set to change linearly. Alternatively, only the first characteristic line LA may be set to change linearly, or only the second characteristic line LB may be set to change linearly. Furthermore, the seventh map M7 may have multi-point information that cannot be expressed by a function.

[0174] In the first and third to fifth embodiments, the control device 4 may have a correction processing unit 70, similar to the second embodiment. The correction processing unit 70 corrects the target pinion angle θ calculated by the target pinion angle calculation unit 62. p* Correction processing is performed on the

[0175] In the first to fifth embodiments, the inclination angle θ of the lever 2B lr However, the steered wheels 5 may be steered in response to an operating force applied to the lever 2B. The operating force is a force required to operate the lever 2B. In this case, a pressure sensor is provided in the steering unit 2. The pressure sensor detects the operating force applied to the lever 2B. The control device 4 determines the target pinion angle θ in response to the detection result of the pressure sensor. p * For example, as the operating force applied to the lever 2B increases, the target pinion angle θ p * The absolute value of increases.

[0176] In the first to fifth embodiments, a dial may be used as the operator of the steering unit 2 instead of the lever 2B. The dial can be rotated clockwise or counterclockwise with a neutral position as a reference. When turning the vehicle to the right relative to the traveling direction, the dial is rotated clockwise. When turning the vehicle to the left relative to the traveling direction, the dial is rotated counterclockwise. In this case, a rotation angle sensor is provided in the steering unit 2. The rotation angle sensor detects the rotation angle of the dial. The control device 4 calculates the target pinion angle θ according to the detection result of the rotation angle sensor. p * For example, as the rotation angle based on the neutral position of the dial increases, the target pinion angle θ p * The absolute value of increases.

[0177] The steering device 1 may have a steering wheel. When the steering unit 2 and the steering wheel coexist, the operator to be used is switched between the steering unit 2 and the steering wheel, for example, by operating a switch provided in the driver's seat. In this case, the steering device 1 may have a reaction force mechanism that applies a steering reaction force to the steering wheel. [Explanation of symbols]

[0178] 1...Steering device 2...Steering unit 2B...Lever (operator) 2C...Tilt angle sensor 3...Steering unit 4...Control device 5...Steering wheel 21...Pinion shaft (shaft) 31...Steering motor

Claims

1. a steering unit in which power transmission between the steering unit and steered wheels of a vehicle is separated, the steering unit including an operator that is operated when turning the vehicle, and a sensor configured to detect an operation amount of the operator; a steering unit having a motor that generates a force for steering the steered wheels; a control device configured to control the motor in accordance with an amount of operation of the operator; the control device is configured to perform a smoothing process on the operation amount of the operator detected through the sensor; the operator is configured to be operable in left-right and front-rear directions relative to the traveling direction of the vehicle, the sensor is configured to be able to detect an operation amount of the operator in a left-right direction and an operation amount of the operator in a front-back direction, The control device is configured to control the motor so that the steered wheels are steered in accordance with an operation amount of the operating element in the left-right direction, and A steering device configured to execute a process for correcting a left-right operation amount of the operator in accordance with a forward-backward operation amount of the operator.

2. a steering unit in which power transmission between the steering unit and steered wheels of a vehicle is separated, the steering unit including an operator that is operated when turning the vehicle, and a sensor configured to detect an operation amount of the operator; a steering unit having a motor that generates a force for steering the steered wheels; a control device configured to control the motor in accordance with an amount of operation of the operator; the control device is configured to perform a smoothing process on the operation amount of the operator detected through the sensor; the control device is configured to calculate a target rotation angle of a shaft that rotates in conjunction with the steered wheels in accordance with an operation amount of the operator, and to control the motor so that an actual angle of the shaft follows the target rotation angle; The control device is configured to increase the target rotation angle by a predetermined second update value every time the operation amount of the operator increases by a predetermined first update value.

3. a steering unit in which power transmission between the steering unit and steered wheels of a vehicle is separated, the steering unit including an operator that is operated when turning the vehicle, and a sensor configured to detect an operation amount of the operator; a steering unit having a motor that generates a force for steering the steered wheels; a control device configured to control the motor in accordance with an amount of operation of the operator; the control device is configured to perform a smoothing process on the operation amount of the operator detected through the sensor; the control device is configured to calculate a target rotation angle of a shaft that rotates in conjunction with the steered wheels in accordance with an operation amount of the operator, and to control the motor so that an actual angle of the shaft follows the target rotation angle; The control device is a steering device configured to calculate the target rotation angle so that the absolute value of the target rotation angle has hysteresis characteristics with respect to changes in the operation amount of the operator when a turning operation and a returning operation are performed through the operator.

4. 3. The steering device according to claim 2, wherein the control device is configured to control the motor so that, when the target rotation angle changes, a deviation between the target rotation angle and an actual angle of the shaft becomes zero over a predetermined gradual change period.

5. The steering device according to claim 4 , wherein the control device is configured to adjust the gradual change period in accordance with a vehicle speed.

6. 4. The steering device according to claim 3, wherein the control device is configured to calculate the target rotation angle so that a rate of change in the target rotation angle relative to a change in the operation amount of the operator increases as the operation amount of the operator increases.

7. The steering device according to any one of claims 1 to 6, wherein the operator is a lever.

Images