Steering control device

Abstract

To provide a steering control device that can suppress discomfort given to a driver, when performing guide display for supporting travelling of a vehicle.SOLUTION: A steering control device calculates a target pinion angle, in accordance with a steering state of a steering wheel. The target pinion angle is a target value of a rotation angle of a pinion shaft that rotates in tandem with steering operation of a steering wheel. The steering control device controls power supply to a steering motor, through execution of feedback control of making an actual angle follow the target pinion angle. The steering control device has a first processing part and a second processing part (66). The first processing part executes processing for changing the target pinion angle, irrelevantly to the steering state of the steering wheel. The second processing part calculates a pinion angle θpa for a back guide monitor function for supporting travelling of a vehicle, by reducing or removing influence given on the pinion angle by changing of the target pinion angle by the first processing part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a steering control 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 reaction motor, which is a source of generating a steering reaction force applied to the steering shaft, and a steering motor, which is a source of generating a steering force that steers the steered wheels. When the vehicle is traveling, a control device of the steering device generates a steering reaction force by controlling the power supply to the reaction motor, and steers the steered wheels by controlling the power supply to the steering motor.

[0003] For example, the control device in Patent Document 1 calculates a target value of the pinion angle according to a steering angle ratio based on the steering angle of the steering wheel. The pinion angle is the rotation angle of a pinion shaft that meshes with a steering shaft that steers the steered wheels. The steering angle ratio is the ratio of the steering angle to the steering angle. The control device performs feedback control of the pinion angle so that the pinion angle calculated based on the rotation angle of the steering motor follows the target value of the pinion angle.

[0004] Furthermore, there have been conventional parking assistance devices that assist in parking a vehicle. For example, the parking assistance device disclosed in Patent Document 2 has a camera and a back guide monitor. The camera captures an image of the rear of the vehicle. When the vehicle is backed into a parking space, the back guide monitor sets a target parking marker in the parking space. The target parking marker and steering are linked to each other. The driver determines the amount of steering while checking the target parking marker. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-142596 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-230594 Summary of the Invention [Problem to be solved by the invention]

[0006] In a steer-by-wire steering system, power transmission between the steering wheel and the steered wheels is separated. Therefore, it is conceivable that the rearview monitor displays guidance to assist the vehicle in backing up, for example, based on the steering state of the steered wheels. In this case, the following concerns arise.

[0007] That is, the control device may execute control to intentionally change the steering angle regardless of steering for the convenience of the steering device or from the viewpoint of product specifications. If the steering angle that is changed regardless of steering is reflected in the guide display, the driver may feel uncomfortable. [Means for solving the problem]

[0008] A steering control device that can solve the above problem calculates a target angle of a shaft that rotates in conjunction with the steering operation of the steered wheels according to the steering state of the steering wheel, in order to control the power supply to a steering motor that generates a steering force for steering the steered wheels of a vehicle whose power transmission is separated from the steering wheel, and performs feedback control to make the actual angle follow the target angle. The steering control device has a first processing unit and a second processing unit. The first processing unit executes processing to change the target angle regardless of the steering state of the steering wheel. The second processing unit calculates a steering state quantity for a guide monitor function to assist driving of the vehicle by reducing or eliminating the effect of the change of the target angle by the first processing unit on the actual angle of the shaft. The guide monitor function includes a function of displaying guide lines indicating a predicted course of the vehicle on a display of the vehicle, and the steering state quantity is used to execute the display of the guide lines.

[0009] According to this configuration, the processing of the second processing unit is executed to obtain a steering state quantity for the guide monitor function in which the influence of the change in the target angle by the first processing unit is reduced or eliminated. This steering state quantity is used for a guide display to assist vehicle driving, and a guide monitor display based on the steering state quantity according to the steering state of the steering wheel is displayed. Therefore, it is possible to prevent the driver from feeling uncomfortable when a guide display to assist vehicle driving is displayed.

[0010] In the above steering control device, the second processing unit may calculate a change amount of the target angle accompanying the processing of the first processing unit, and calculate the steering state quantity by subtracting the change amount of the target angle from the actual angle of the shaft or the target angle based on the steering state of the steering wheel.

[0011] According to this configuration, the steering state quantity to be used for display on the guide monitor can be easily calculated by subtracting the change in the target angle of the shaft resulting from processing by the first processing unit from the actual angle of the shaft or the target angle based on the steering state of the steering wheel.

[0012] In the above steering control device, the processing of the first processing unit may be such that, when the vehicle power source is turned on, a first change process is executed to calculate an offset angle, which is the amount of deviation between a target angle calculated based on the current steering angle of the steering wheel and an actual angle of the shaft that reflects the actual steering state of the steered wheels, and to gradually change the offset angle toward 0 by applying a gradual change process to the offset angle, and to change the value of the target angle by adding the offset angle that has been subjected to the gradual change process to the target angle.

[0013] With this configuration, when the vehicle power is turned on, the offset angle is added to the target angle of the shaft while gradually changing over time toward 0. This makes it possible to suppress sudden changes in the target angle of the shaft, and ultimately in the steering angle of the steered wheels. This also makes it possible to suppress any sense of discomfort felt by the driver.

[0014] In the above steering control device, the processing of the second processing unit may include processing to take in the offset angle that has been subjected to the gradual change processing as a first change amount, and calculate the steering state amount by subtracting the first change amount from the actual angle of the shaft or the target angle based on the steering state of the steering wheel.

[0015] According to this configuration, the first change amount is subtracted from the actual angle of the shaft or the target angle based on the steering state of the steering wheel, thereby obtaining a steering control amount in which the influence of the change in the target angle due to the execution of the first change process is eliminated or reduced.

[0016] In the above steering control device, the processing of the first processing unit may further include executing a second change process to change the value of the target angle when the steering shaft that steers the steered wheels moves to a position within a predetermined high axial force range, so that the position of the steering shaft deviates from the high axial force range toward the steering neutral position.

[0017] This configuration can prevent situations where the output of the steering motor may be insufficient, thereby preventing the driver from feeling uncomfortable due to insufficient output of the steering motor.

[0018] In the above steering control device, the processing of the second processing unit may include processing to take in the target angle before and after execution of the second change processing, calculate a second change amount by subtracting the target angle before execution of the second change processing from the target angle after execution of the second change processing, and calculate the steering state amount by subtracting the second change amount from the actual angle of the shaft or the target angle based on the steering state of the steering wheel.

[0019] According to this configuration, the second change amount is subtracted from the actual angle of the shaft or the target angle based on the steering state of the steering wheel, thereby obtaining a steering control amount from which the influence of the change in the target angle due to the execution of the second change process has been removed.

[0020] In the above steering control device, the processing of the first processing unit may further include executing a third change process that changes the value of the target angle in order to reduce residual current generated in the steering motor.

[0021] According to this configuration, the residual current generated in the steering motor is reduced. By reducing the residual current in the steering motor, it is possible to reduce the effect of the residual current on the torque generated by the steering motor.

[0022] In the above-mentioned steering control device, the processing of the second processing unit may include processing to take in the target angle before and after execution of the third change process, calculate a third change amount by subtracting the target angle before execution of the third change process from the target angle after execution of the third change process, and calculate the steering state amount by subtracting the third change amount from the actual angle of the shaft or the target angle based on the steering state of the steering wheel.

[0023] According to this configuration, the third change amount is subtracted from the actual angle of the shaft or the target angle based on the steering state of the steering wheel, thereby obtaining a steering control amount from which the influence of the change in the target angle due to the execution of the third change process has been removed.

[0024] In the above steering control device, the steering state quantity may be a rotation angle of a pinion shaft that meshes with a steering shaft that steers the steered wheels. With this configuration, the pinion shaft meshing with the steered shaft is a state variable that reflects the steered state of the steered wheels. [Effects of the Invention]

[0025] According to the steering control device of the present invention, when a guide display for assisting vehicle driving is displayed, it is possible to suppress the driver from feeling uncomfortable. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a configuration diagram of a steer-by-wire steering device in which an embodiment of a steering control device is mounted. [Figure 2] FIG. 1 is a block diagram of an embodiment of a steering control device. [Figure 3] FIG. 4 is a block diagram of a target pinion angle calculation unit according to an embodiment. [Figure 4] FIG. 2 is a block diagram of an adjustment processing unit according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0027] An embodiment of a steering control device will be described below. <Overall structure> As shown in Fig. 1, the control target of the steering control device 1 is a steer-by-wire steering device 2. The steering device 2 has a steering mechanism 3 and a turning mechanism 4. The steering mechanism 3 is a mechanical part that is steered by a driver via a steering wheel 5. The turning mechanism 4 is a mechanical part that steers steerable wheels 6 of the vehicle in response to the steering of the steering wheel 5.

[0028] The steering mechanism 3 has a steering shaft 11, a reaction motor 12, and a reducer 13. The steering wheel 5 is connected to the steering shaft 11 so as to be rotatable integrally therewith. The reaction motor 12 is a source of a steering reaction force applied to the steering shaft 11. The steering reaction force is a force in the opposite direction to the steering direction of the steering wheel 5. The reaction motor 12 is, for example, a three-phase brushless motor. The reducer 13 decelerates the rotation of the reaction motor 12 and transmits the decelerated rotation to the steering shaft 11.

[0029] The steering mechanism 4 has a pinion shaft 21, a steered shaft 22, and a housing 23. The housing 23 rotatably supports the pinion shaft 21. The housing 23 also accommodates the steered shaft 22 so that it can reciprocate. The pinion shaft 21 is arranged to intersect with the steered shaft 22. Pinion teeth 21a of the pinion shaft 21 mesh with rack teeth 22a of the steered shaft 22. Tie rods 25 are connected to both ends of the steered 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 6 are assembled.

[0030] The steering mechanism 4 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 6. 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.

[0031] The steered shaft 22 moves in the axial direction, and the steered angle θ of the steered wheels 6 wThe pinion teeth 21a of the pinion shaft 21 are engaged with the rack teeth 22a of the steered shaft 22, and therefore rotate in conjunction with the movement of the steered shaft 22. The pinion shaft 21 is a shaft that rotates in conjunction with the steering operation of the steered wheels 6.

[0032] The steering control device 1 controls the operation of the reaction force motor 12 and the steering motor 31. The steering control device 1 has a processing circuit including any one of the following three components A1, A2, A3.

[0033] 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. 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.

[0034] 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.

[0035] The steering control device 1 receives detection results from sensors mounted on the vehicle, including a vehicle speed sensor 41, a torque sensor 42, a rotation angle sensor 43, and a rotation angle sensor 44. The vehicle speed sensor 41 detects the vehicle speed V. The torque sensor 42 is provided on the steering wheel 5 side, with the connection part of the steering shaft 11 to the reducer 13 as a reference. The torque sensor 42 detects the steering torque Th applied to the steering shaft 11. The steering torque Th is calculated based on the amount of twist of a torsion bar 42a provided on the steering shaft 11. The rotation angle sensor 43 is provided on the reaction force motor 12. The rotation angle sensor 43 detects the rotation angle θ of the reaction force motor 12. a The rotation angle sensor 44 is provided on the steering motor 31. The rotation angle sensor 44 detects the rotation angle θ of the steering motor 31. b Detect.

[0036] Steering torque Th, rotation angle θ of reaction motor 12 a , and the rotation angle θ of the steering motor 31 b is, for example, a positive value when the steering wheel 5 is steered to the right, and is a negative value when the steering wheel 5 is steered to the left.

[0037] Steering control device 1 controls reaction force motor 12 and turning motor 31 based on the detection results of various sensors. Steering control device 1 controls the power supply to reaction force motor 12 so that reaction force motor 12 generates a steering reaction force corresponding to steering torque Th. Steering control device 1 controls the power supply to turning motor 31 so that steered wheels 6 are steered according to the steering state of steering wheel 5.

[0038] <Configuration of the driving assistance control device 45> A vehicle may be equipped with a driving assistance system. The driving assistance system realizes various driving assistance functions to further improve the safety or convenience of the vehicle. The vehicle has a driving assistance control device 45 that controls the control devices of various on-board systems. Like the steering control device 1, the driving assistance control device 45 has a processing circuit that includes any one of the three configurations A1, A2, and A3 described above.

[0039] The driving assistance control device 45 determines the optimal control method based on the vehicle's current state and issues individual control commands to various on-board control devices according to the determined control method. The driving assistance control device 45 switches the driving assistance function between on and off through the operation of a switch (not shown) provided in the driver's seat or the like. The driving assistance control device 45 is connected to the steering control device 1 via an on-board network 46 such as a CAN.

[0040] The driving assistance function includes a parking assist function. The parking assist function is a function for assisting the driver in steering when parking, such as when parking in a garage. When the parking assist function is executed, the driving assistance control device 45 intervenes in the steering control by the steering control device 1. When executing the parking assist function, the driving assistance control device 45 issues a command value θ to the steering control device 1 based on the running state of the vehicle and the surrounding conditions of the vehicle. * Generate.

[0041] Command value θ * is a target value of the steering state quantity required to park the vehicle at a predetermined parking position depending on the vehicle's running state and the vehicle's surrounding conditions at that time. The target value of the steering state quantity is the value of the steering state quantity to be added to the current steering state quantity or the target value of the current steering state quantity. The steering state quantity is a state quantity that reflects the steering state of the steered wheels 6, and for example, the pinion angle θ p In this case, the command value θ * is the pinion angle θ p Or pinion angle θ p The steering control device 1 uses the command value θ generated by the driving assistance control device 45 to add the target value θ * The steering motor 31 is controlled based on the above.

[0042] The driving assistance control device 45 takes in the vehicle speed V detected by the vehicle speed sensor 41. The driving assistance control device 45 also takes in the steering state quantity from the steering control device 1. The driving assistance control device 45 recognizes the state of the vehicle based on the vehicle speed V and the steering state of the steered wheels 6. The driving assistance control device 45 is connected to a camera 47 mounted on the vehicle. The camera 47 includes a backup camera that captures images behind the vehicle. The driving assistance control device 45 recognizes the situation around the vehicle through the camera 47.

[0043] The driving assistance control device 45 is connected to an HMI (Human Machine Interface) 48. The HMI 48 mediates the exchange of information between the driver and the driving assistance control device 45. The HMI 48 includes an input device and an output device. The input device includes buttons and a touch panel for performing various input operations. The output device includes a display for displaying various types of information.

[0044] The driving assistance control device 45 has a back guide monitor function as one of its driving assistance functions. The back guide monitor function displays an image of the area behind the vehicle on the display of the HMI 48 to assist in backing operations such as parking. When the vehicle is being backed up, the driving assistance control device 45 displays an image of the area behind the vehicle and guide lines on the display of the HMI 48. The driving assistance control device 45 recognizes that the vehicle is being backed up by, for example, switching the shift range of the transmission to the reverse position.

[0045] The guide lines include, for example, predicted course lines of the vehicle, vehicle width extension lines, and distance guide lines. The predicted course lines are lines that indicate the approximate course of the vehicle in conjunction with the operation of the steering wheel 5 or the steering operation of the steered wheels 6. The vehicle width extension lines are lines that indicate the approximate course of the vehicle when the vehicle is reversed straight. The distance guide lines are lines that indicate the distance from the rear of the vehicle, for example, 0.5 meters or 1.0 meters.

[0046] The driving assistance control device 45 sets a driving assistance request flag FB Set the value of the driving assistance request flag F B is information indicating whether the driver is requesting driving assistance from the system. When the driving assistance function is turned on or the shift range of the transmission is switched to the reverse position, the driving assistance control device 45 sets the driving assistance request flag F B The driving assistance control device 45 sets the value of the driving assistance request flag F to "1" when the driving assistance function is turned off or when the shift range of the transmission is not in the reverse position. B Set the value to "0".

[0047] <Configuration of steering control device 1> Next, the configuration of the steering control device 1 will be described. As shown in FIG. 2, the steering control device 1 has a reaction force control section 50 that performs reaction force control, and a steering control section 60 that performs steering control.

[0048] The reaction force control unit 50 includes a steering angle calculation unit 51 , a reaction force torque command value calculation unit 52 , and an energization control unit 53 . The steering angle calculation unit 51 calculates the rotation angle θ of the reaction force motor 12 detected through the rotation angle sensor 43. a Based on this, the steering angle θ of the steering wheel 5 s Calculate the following.

[0049] The reaction torque command value calculation unit 52 calculates the reaction torque command value T * Calculate the reaction torque command value T * is a target value of the steering reaction force to be generated by the reaction motor 12. The steering reaction force is a torque in the direction opposite to the steering direction of the steering wheel 5.

[0050] The reaction torque command value calculation unit 52 calculates the steering torque T h , and the vehicle speed V detected by the vehicle speed sensor 41. The reaction torque command value calculation unit 52 calculates the steering torque T hand vehicle speed V, the assist torque command value is calculated. The assist torque command value corresponds to the target value of the assist torque when the steering device 2 is an electric power steering device. The assist torque is a force for assisting the steering of the steering wheel 5. The assist torque command value is a torque in the same direction as the steering direction of the steering wheel 5. The steering torque T h The larger the absolute value of the assist torque command value is and the slower the vehicle speed V is, the larger the absolute value of the assist torque command value is.

[0051] The reaction torque command value calculation unit 52 calculates the pinion angle θ calculated by the pinion angle calculation unit 61. p , and the current I of the steering motor 31 detected through the current sensor 65 b The reaction torque command value calculation unit 52 takes in the value of the pinion angle θ p , and the current I of the steering motor 31 b The reaction torque command value calculation unit 52 calculates the axial force torque acting on the steering shaft 22 based on the value of the reaction torque command T. The reaction torque command value calculation unit 52 calculates the axial force torque by converting the calculated axial force into a torque for the steering shaft 11. The reaction torque command value calculation unit 52 calculates the reaction torque command value T by subtracting the axial force torque from the assist torque command value. * Calculate the following.

[0052] The power supply control unit 53 determines the reaction torque command value T * Specifically, the power supply control unit 53 supplies the reaction force motor 12 with power according to the reaction force torque command value T * The current control unit 53 calculates a current command value for the reaction force motor 12 based on the current I generated in the power supply path through a current sensor 54 provided in the power supply path for the reaction force motor 12. a Detect the value of the current I a The value of is the value of the current supplied to the reaction motor 12. The current control unit 53 calculates the current command value and the current I a The deviation from the value of the reaction torque command value T is calculated, and the power supply to the reaction motor 12 is controlled so as to eliminate the deviation. * A torque corresponding to the

[0053] The steering control unit 60 has a pinion angle calculation unit 61 , a target pinion angle calculation unit 62 , a pinion angle feedback control unit 63 , and an energization control unit 64 . The pinion angle calculation unit 61 calculates the rotation angle θ of the steering motor 31 detected through the rotation angle sensor 43. 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 meshed 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 6 w This is a value that reflects the

[0054] The target pinion angle calculation unit 62 calculates the steering angle θ calculated by the steering angle calculation unit 51. s Based on the target pinion angle θ p * The target pinion angle calculation unit 62 calculates the target pinion angle θ so as to realize a steering angle ratio set according to product specifications, etc. p * The steering angle ratio is calculated by the steering angle θ s steering angle θ w is the ratio of

[0055] The target pinion angle calculation unit 62 sets a steering angle ratio according to the vehicle running state, such as the vehicle speed V, and calculates the target pinion angle θ according to the set steering angle ratio. p * As the vehicle speed V decreases, the target pinion angle calculation unit 62 calculates the steering angle θ s steering angle θw The target pinion angle θ p * As the vehicle speed V increases, the target pinion angle calculation unit 62 calculates the steering angle θ s steering angle θ w The target pinion angle θ p * The target pinion angle calculation unit 62 calculates the steering angle θ s The correction angle for the steering angle θ is calculated. s By adding to the target pinion angle θ according to the steering angle ratio p * Calculate the following.

[0056] Depending on the product specifications, the target pinion angle calculation unit 62 may calculate the target pinion angle θ so that the steering angle ratio becomes "1:1" regardless of the running state of the vehicle. p * The following may be calculated.

[0057] 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.

[0058] 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 65 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

[0059] The steering control unit 60 has an adjustment processing unit 66 and a state determination unit 67. The adjustment processing unit 66 calculates a steering state quantity used when the driving assistance control device 45 executes the back guide monitor function. The steering state quantity is, for example, a pinion angle θ p The adjustment processing unit 66 adjusts the pinion angle θ calculated by the pinion angle calculation unit 61. p By adjusting the pinion angle θ for the back guide monitor function used by the driving assistance control device 45, pa Calculate the following.

[0060] The adjustment processing unit 66 may, for example, set the driving assistance request flag F B The operation may be started when the value of the driving assistance request flag F changes to "1". B When the value of is "0", the adjustment processing unit 66 is kept in a stopped state.

[0061] The state determination unit 67 sets the activation determination flag F depending on whether the vehicle power supply is turned on. A The vehicle power supply is switched on and off by operating a start switch provided at the driver's seat. When the wake-up signal is received, the state determination unit 67 determines that the vehicle power supply is on. When the wake-up signal is not received, the state determination unit 67 determines that the vehicle power supply is off.

[0062] The wake-up signal is an activation signal for the steering control device 1. The wake-up signal is power (voltage) supplied to the steering control device 1 via, for example, an ignition switch when the power position of the vehicle is in the ON position. When the vehicle power supply is turned on, the state determination unit 67 sets the activation determination flag F A The state determination unit 67 sets the value of the activation determination flag F A Set the value to "0".

[0063] When the vehicle power supply is turned off, the steering control device 1 transitions from a normal operation state to a sleep state, which is a power-saving mode. In the sleep state, the steering control device 1 is in a state where the power is turned off except for some electronic circuits. When the vehicle power supply is turned on in the sleep state, the steering control device 1 starts up and transitions from the sleep state to a normal operation state. The normal operation state is a state in which the power-saving operation state is canceled.

[0064] <Detailed Configuration of Target Pinion Angle Calculation Unit 62> Next, the configuration of the target pinion angle calculation unit 62 will be described in detail. As shown in FIG. 3, the target pinion angle calculation unit 62 has a first conversion processing unit 71, a second conversion processing unit 72, an output compensation processing unit 73, an addition processing unit 74, an offset angle calculation unit 75, a gradual change processing unit 76, and a residual current reduction processing unit 77.

[0065] The first conversion processing unit 71 converts the steering angle θ calculated by the steering angle calculation unit 51 into s The first conversion processing unit 71 takes in the steering angle θ s The first target pinion angle θ p1 * The first conversion processing unit 71 converts, for example, the steering angle θ s By adding the adjustment amount to the first target pinion angle θ p1 * The adjustment amount is calculated based on the steering angle θ s steering angle θ w Based on the steering angle ratio, which is the ratio of the steering angle θ sThe pinion angle θ p To convert to steering angle θ s The steering angle ratio is the angle to be added to the steering angle θ s and steering angle θ w The first conversion processing unit 71 changes the value of the adjustment amount in accordance with the value of the vehicle speed V. For example, the first conversion processing unit 71 determines the static characteristics between the steering angle θ s First target pinion angle θ p1 * The value of the adjustment amount is changed so that the change in

[0066] The second conversion processing unit 72 converts the first target pinion angle θ p1 * The second conversion processing unit 72 has a filter. The second conversion processing unit 72 takes in the first target pinion angle θ p1 * By filtering the second target pinion angle θ p2 * The filter has a transfer function that defines dynamic characteristics according to the vehicle speed V, for example. That is, the second conversion processing unit 72 calculates the steering angle θ s and the second target pinion angle θ p2 * The first target pinion angle θ is set so that desired characteristics are obtained between p1 * The second target pinion angle θ p2 * Convert to.

[0067] The output compensation processing unit 73 calculates the second target pinion angle θ p2 *The output compensation processing unit 73 executes processing to compensate for a lack of output from the steering motor 31. As the steering shaft 22 approaches the limit position of its physical range of movement, the axial force acting on the steering shaft 22 increases. A predetermined range from the limit position of the physical range of movement of the steering shaft 22 toward the steering neutral position corresponding to the vehicle traveling straight ahead is set as a high axial force range in which the axial force increases. The high axial force range is set, for example, based on the maximum torque that the steering motor 31 can generate.

[0068] The output compensation processing unit 73 calculates, for example, the rotation angle θ of the steering motor 31. b When steered shaft 22 moves to a position within the high axial force range, output compensation processing section 73 adjusts second target pinion angle θ so that the position of steered shaft 22 deviates from the high axial force range towards the steered neutral position. p2 * The output compensation processing unit 73 corrects the value of the second target pinion angle θ p2 * The output compensation processing unit 73 calculates a correction angle for the second target pinion angle θ p2 * The third target pinion angle θ is obtained by subtracting the correction angle from p3 * Calculate the following.

[0069] The limit position of the physical range of movement of steered shaft 22 is a position where so-called end contact occurs, physically restricting the range of movement of steered shaft 22. End contact occurs when rack end 24, which is the end of steered shaft 22, contacts housing 23.

[0070] The addition processing unit 74 calculates the third target pinion angle θ p3 * The driving assistance control device 45 also takes in the command value θ * is generated, the addition unit 74 calculates the command value θ * The driving assistance control device 45 takes in the command value θ* is generated, the addition processing unit 74 calculates the third target pinion angle θ p3 * command value θ * By adding the above, the fourth target pinion angle θ p4 * The driving support control device 45 calculates the command value θ * If the third target pinion angle θ p3 * This is the fourth target pinion angle θ p4 * This becomes:

[0071] The offset angle calculation unit 75 calculates the offset angle θ o1 Calculate the offset angle θ o1 is the current steering angle θ when the vehicle power is turned on s The target pinion angle θ is calculated based on p * and the current steering angle θ when the vehicle power is turned on. w The corresponding pinion angle θ p The pinion angle θ is the deviation from p The value of is the rotation angle θ of the steering motor 31 when the vehicle power is turned on. b Alternatively, it may be a value stored in the storage device of the steering control device 1 when the vehicle power supply was turned off last time.

[0072] The offset angle calculation unit 75 calculates the start determination flag F A The offset angle calculation unit 75 takes in the value of the start determination flag F A Based on the value of the start-up determination flag F A When the value of is "1", that is, when the vehicle power is turned on, the offset angle θ o1 The offset angle calculation unit 75 calculates the start determination flag F A When the value of is "0", that is, when the vehicle power is off, the offset angle θ o1 does not calculate.

[0073] The gradual change processing unit 76 calculates a fourth target pinion angle θ p4 * and offset angle θ o1 The gradual change processing unit 76 takes in the offset angle θ o1 The gradual change processing unit 76 has an upper limit and a lower limit for the absolute value of the offset angle θ o1 If the absolute value of exceeds the upper limit, or if the offset angle θ o1 If the absolute value of is below the lower limit, the offset remaining value θ o2 Calculate the remaining offset value θ o2 is the offset angle θ o1 The difference between the absolute value of and the upper limit, or the offset angle θ o1 The gradual change processing unit 76 calculates the difference between the absolute value of the offset angle θ o1 From the absolute value of the offset angle θ o1 The difference between the upper limit and the offset angle θ o1 The final offset angle θ is calculated by subtracting the difference between the absolute value of o3 Calculate the following.

[0074] In addition, the offset angle θ o1 When the absolute value of is within the range specified by the upper and lower limits, the final offset angle θ o3 is the offset angle θ o1 will be the same value as The gradual change processing unit 76 calculates a fourth target pinion angle θ p4 * The final offset angle θ o3 By adding the above, the fifth target pinion angle θ p5 * However, the gradual change processing unit 76 calculates the final offset angle θ o3 The gradual change processing unit 76 performs gradual change processing with respect to time on the final offset angle θ o3 The gradual change processing unit 76 gradually changes the steering angle θ sAlternatively, the steering state of the steering wheel 5 is recognized based on the steering angular velocity. The steering angular velocity is determined by the steering angle θ s is obtained by differentiating

[0075] The residual current reduction processing unit 77 calculates the fifth target pinion angle θ p5 * Residual current reduction processing section 77 executes processing to reduce the residual current generated in steering motor 31. The residual current is, for example, p The residual current is generated due to the twisting of the tire caused by the execution of the feedback control. The residual current is generated steadily. The residual current reduction processing unit 77 reduces the current I of the steering motor 31. b or a current command value for steering motor 31. Residual current reduction processing section 77 calculates a correction angle for reducing the residual current based on the value of the residual current. The correction angle is the rotation angle of pinion shaft 21. Residual current reduction processing section 77 calculates a fifth target pinion angle θ p5 * By subtracting the correction angle from the p * Calculate the following.

[0076] <Detailed configuration of the adjustment processing unit 66> Next, the configuration of the adjustment processing unit 66 will be described in detail. The adjustment processing unit 66 adjusts the pinion angle θ , which is a steering state quantity used when the driving assistance control device 45 executes the back guide monitor function. pa The adjustment processing unit 66 calculates the pinion angle θ calculated by the pinion angle calculation unit 61. p From the above, the target pinion angle θ p * By reducing or eliminating the influence of the change in the pinion angle θ pa Calculate the following.

[0077] B1. First Changing Process The first changing process is a process for changing the target pinion angle θ p* This is a change process. B2. Second Changing Process The second changing process is a process for changing the target pinion angle θ p * This is a change process.

[0078] B3. Third Changing Process The third changing process is a process for changing the target pinion angle θ p * This is a change process. Through the execution of the three processes B1 to B3, the target pinion angle θ p * The three processes B1 to B3 are executed regardless of the steering state of the steering wheel 5 by the driver. The three processes B1 to B3 are executed for the convenience of the steering device 2 or from the viewpoint of product specifications. That is, the target pinion angle θ p * The amount of change is an amount of change that is changed for the convenience of the steering device 2 or from the viewpoint of product specifications.

[0079] The pinion angle feedback control unit 63 receives the pinion angle θ calculated by the pinion angle calculation unit 61. p is the target pinion angle θ p * The pinion angle θ p Therefore, the pinion angle θ calculated by the pinion angle calculation unit 61 is p The value of is initially calculated based on the steering angle θ s Target pinion angle θ based on p * The target pinion angle θ calculated by the first conversion processing unit 71 is different from the value p * is a value according to the steering state of the steering wheel 5 by the driver.

[0080] Therefore, the target pinion angle θ obtained through the three processes B1 to B3 is p *The pinion angle θ is feedback controlled based on p is used to execute the back guide monitor function, there is a risk that the vehicle cannot be properly guided in reverse. In addition, the driver may feel uncomfortable when guidance is given that differs from the steering state of the steering wheel 5. For this reason, the pinion angle θ used when executing the back guide monitor function is pa is the target pinion angle θ associated with the execution of the three processes B1 to B3. p * It is preferable that the influence of the change in the temperature is reduced or eliminated.

[0081] Therefore, in this embodiment, the adjustment processing unit 66 has the following configuration. As shown in FIG. 4, the adjustment processing unit 66, for example, sets the activation determination flag F A The adjustment processing unit 66 starts its operation when the value of is set to "1." The adjustment processing unit 66 has a first change amount calculation unit 81, a second change amount calculation unit 82, a third change amount calculation unit 83, and a calculator 84.

[0082] The first change amount calculation unit 81 calculates, for example, the final offset angle θ o3 is acquired as the first change amount Δθ1. The first change amount Δθ1 is calculated by the offset angle calculation unit 75 and the gradual change processing unit 76. p * is the amount of change.

[0083] The first change amount calculation unit 81 calculates the final offset angle θ o3 The first change amount Δθ1 may be calculated by multiplying the target pinion angle θ by a predetermined gain. p * The gain value may be set to "1".

[0084] The second change amount calculation unit 82 calculates the second change amount Δθ2. The second change amount Δθ2 is calculated based on the target pinion angle θ p * The second change amount calculation unit 82 calculates the second target pinion angle θ p2 * , and the third target pinion angle θ calculated by the output compensation processing unit 73. p3 * The second change amount calculation unit 82 calculates the third target pinion angle θ p3 * to the second target pinion angle θ p2 * The second change amount Δθ2 is calculated by subtracting

[0085] The third change amount calculation unit 83 calculates a third change amount Δθ3. The third change amount Δθ3 is calculated based on the target pinion angle θ p * The third change amount calculation unit 83 calculates the fifth target pinion angle θ calculated by the gradual change processing unit 76. p5 * , and the final target pinion angle θ calculated by the residual current reduction processing unit 77. p * The third change amount calculation unit 83 calculates the final target pinion angle θ p * to the fifth target pinion angle θ p5 * The third change amount Δθ3 is calculated by subtracting

[0086] The calculator 84 calculates the pinion angle θ calculated by the pinion angle calculator 61. p Furthermore, calculator 84 takes in the first change amount Δθ1 calculated by first change amount calculator 81, Δθ2 calculated by second change amount calculator 82, and third change amount Δθ3 calculated by third change amount calculator 83.

[0087] The calculator 84 calculates the start determination flag F AWhen the value of changes from "0" to "1", that is, when the vehicle power is turned on, the following processing is executed to set the pinion angle θ for the back guide monitor function. pa That is, the calculator 84 calculates the pinion angle θ calculated by the pinion angle calculator 61. p The calculator 84 subtracts the first change amount Δθ1 from the value of the pinion angle θ calculated by the pinion angle calculator 61. p Through the execution of this calculation process, the calculator 84 calculates the pinion angle θ for the back guide monitor function. pa Calculate.

[0088] <Correspondence> The pinion shaft 21 corresponds to a shaft that rotates in conjunction with the steering operation of the steered wheels 6. Target pinion angle θ p * corresponds to the target angle of the shaft that rotates in conjunction with the steering operation of the steered wheels 6. p corresponds to the actual angle, which is the actual rotation angle of the shaft that rotates in conjunction with the steering operation of the steered wheels 6.

[0089] The output compensation processing unit 73, the offset angle calculation unit 75, and the residual current reduction processing unit 77 constitute a first processing unit. The first processing unit calculates the target pinion angle θ p * This is a processing unit that executes processing to change the value.

[0090] The adjustment processing unit 66 corresponds to a second processing unit. The second processing unit adjusts the target pinion angle θ p * The change in pinion angle θ p The adjustment processing unit 66 is a processing unit that calculates the steering state quantity for the back guide monitor function by reducing or eliminating the influence of the pinion angle θ pa corresponds to the steering state quantity for the back guide monitor function.

[0091] <Operation of this embodiment> This embodiment provides the following effects. The value of the first change amount Δθ1 is basically determined by the final offset angle θ calculated by the gradual change processing unit 76. o3 The pinion angle θ calculated by the pinion angle calculation unit 61 is an angle having the same value as p The pinion angle θ p Therefore, the target pinion angle θ resulting from the execution of the previous process B1 by the offset angle calculation unit 75 is p * That is, the influence of the change in the pinion angle θ for the back guide monitor function is eliminated or reduced. pa is the target pinion angle θ associated with the execution of the previous process B1 that is executed when the steering control device 1 is started. p * The angle is such that the effect of the change in

[0092] The second change amount Δθ2 is the target pinion angle θ p * This second change amount Δθ2 is the change amount of the pinion angle θ calculated by the pinion angle calculation unit 61. p By subtracting from the pinion angle θ p Therefore, the target pinion angle θ p * That is, the influence of the change in the pinion angle θ for the back guide monitor function is eliminated or reduced. pa is the target pinion angle θ obtained by executing the previous process B2. p * The angle is such that the effect of the change in

[0093] The third change amount Δθ3 is the change amount of the target pinion angle θ p * This third change amount Δθ3 is the change amount of the pinion angle θ calculated by the pinion angle calculation unit 61. p By subtracting from the pinion angle θ pTherefore, the target pinion angle θ resulting from the execution of the previous process B3 by the residual current reduction processing unit 77 p * That is, the influence of the change in the pinion angle θ for the back guide monitor function is eliminated or reduced. pa is the target pinion angle θ obtained by executing the previous process B3. p * The angle is such that the effect of the change in

[0094] The driving assistance control device 45 adjusts the pinion angle θ for the back guide monitor function calculated by the adjustment processing unit 66. pa The back guide monitor function is executed using the pinion angle θ for the back guide monitor function. pa is the target pinion angle θ associated with the execution of the preceding processes B1 to B3, which are executed regardless of the steering state of the steering wheel 5. p * That is, the pinion angle θ for the back guide monitor function is an angle at which the influence of the change in pa is the virtual pinion angle θ according to the steering state of the steering wheel 5. p Therefore, the driving assistance control device 45 can execute the back guide monitor function in accordance with the steering state of the steering wheel 5.

[0095] <Effects of the embodiment> This embodiment has the following advantages. (1) For the convenience of the steering device 2 or from the viewpoint of product specifications, the steering control device 1 does not set the target pinion angle θ regardless of the steering state of the steering wheel 5. p * When the driving assistance control device 45 executes the back guide monitor function, the driving assistance control device 45 may change the pinion angle θ for the back guide monitor function calculated by the adjustment processing unit 66. pa Use the pinion angle θ pa is the target pinion angle θ associated with the execution of the processes B1 to B3, regardless of the steering state of the steering wheel 5. p *This is an angle at which the influence of the change in the angle is eliminated or reduced. Therefore, the driving assistance control device 45 can execute the back guide monitor function in accordance with the steering state of the steering wheel 5. Therefore, it is possible to prevent the guide display accompanying the execution of the back guide monitor function from giving the driver an uncomfortable feeling.

[0096] (2) The adjustment processing unit 66 adjusts the target pinion angle θ associated with the processing performed independently of the steering state of the steering wheel 5. p * The amount of change in the pinion angle θ calculated by the pinion angle calculation unit 61 p By subtracting from the pinion angle θ pa can be easily calculated.

[0097] (3) When the vehicle power is turned on, the target pinion angle θ p * The offset angle θ o1 , more precisely, the final offset angle θ limited to a value within a range specified by upper and lower limits. o3 is reflected. Offset angle θ o1 is the current steering angle θ s The target pinion angle θ to be calculated based on p * and the actual steering angle θ w Target pinion angle θ corresponding to p * The target pinion angle θ p * The final offset angle θ reflected in o3 is gradually decreased over time. Therefore, when the vehicle power is turned on, the target pinion angle θ p * , and thus the steering angle θ w Therefore, it is possible to suitably prevent the driver from feeling uncomfortable.

[0098] (4) The adjustment processing unit 66 calculates the final offset angle θ o3The adjustment processing unit 66 takes in the pinion angle θ calculated by the pinion angle calculation unit 61 as the first change amount Δθ1. p By subtracting the first change amount Δθ1 from the target pinion angle θ p * The effect of the change in pinion angle θ is removed. pa can be easily calculated.

[0099] (5) Output compensation processing unit 73 executes processing to compensate for a lack of output from steering motor 31. That is, when the position of steering shaft 22 moves to a position within the high axial force range, output compensation processing unit 73 adjusts target pinion angle θ so that the position of steering shaft 22 moves out of the high axial force range toward the steering neutral position. p * Therefore, it is possible to prevent a situation in which the output of steering motor 31 is insufficient. Therefore, it is possible to prevent the driver from feeling uncomfortable due to insufficient output of steering motor 31.

[0100] (6) The adjustment processing unit 66 calculates the second target pinion angle θ before the processing of the output compensation processing unit 73 is executed. p2 * and the third target pinion angle θ after the processing of the output compensation processing unit 73 is executed. p3 * The adjustment processing unit 66 takes in the third target pinion angle θ p3 * to the second target pinion angle θ p2 * The adjustment processing unit 66 calculates the second change amount Δθ2 by subtracting the pinion angle θ calculated by the pinion angle calculation unit 61. p By subtracting the second change amount Δθ2 from the target pinion angle θ p * The effect of the change in pinion angle θ is removed. pa can be easily calculated.

[0101] (7) Residual current reduction processing section 77 executes processing for reducing the residual current generated in steering motor 31. Residual current reduction processing section 77, for example, reduces the current I b The residual current reduction processing section 77 calculates the value of the residual current of the steering motor 31 based on the value of the target pinion angle θ p * By reducing the residual current of steering motor 31, the effect of the residual current on the torque generated by steering motor 31 can be reduced.

[0102] (8) The adjustment processing unit 66 calculates the fifth target pinion angle θ before the processing of the residual current reduction processing unit 77 is executed. p5 * and the final target pinion angle θ after the processing of the output compensation processing unit 73 is executed. p * The adjustment processing unit 66 takes in the final target pinion angle θ p * to the fifth target pinion angle θ p5 * The adjustment processing unit 66 calculates the third change amount Δθ3 by subtracting the pinion angle θ calculated by the pinion angle calculation unit 61. p By subtracting the third change amount Δθ3 from the target pinion angle θ p * The effect of the change in pinion angle θ is removed. pa can be easily calculated.

[0103] <Other embodiments> This embodiment may be modified as follows. The adjustment processing unit 66 may have a guard processing unit 85. The guard processing unit 85 adjusts the pinion angle θ for the back guide monitor function calculated by the calculator 84. pa The guard processing unit 85 takes in the pinion angle θ pa The guard processing unit 85 has an upper limit and a lower limit for the pinion angle θ paThe guard processing unit 85 performs a limiting process on the pinion angle θ pa If the absolute value of exceeds the upper limit or falls below the lower limit, the pinion angle θ pa By this process, the absolute value of the pinion angle θ pa The calculation of the pinion angle θ pa Therefore, the delay in responding to changes in the frequency band is suppressed.

[0104] The gradual change processing unit 76 adjusts the offset angle θ calculated by the offset angle calculation unit 75. o1 In this case, the final offset angle θ o3 is the offset angle θ calculated by the offset angle calculation unit 75 o1 will be the same value as

[0105] The adjustment processing unit 66 adjusts the pinion angle θ calculated by the pinion angle calculation unit 61. p Instead, the first target pinion angle θ calculated by the first conversion processing unit 71 p1 * The first target pinion angle θ p1 * is the pinion angle θ calculated according to the steering state of the steering wheel 5. p The adjustment processing unit 66 adjusts the first target pinion angle θ p1 * The pinion angle θ for the back guide monitor function is calculated by subtracting the first change amount Δθ1, the second change amount Δθ2, and the third change amount Δθ3 from pa The following may be calculated.

[0106] The target pinion angle calculation unit 62 may be configured without the second conversion processing unit 72. In this case, the output compensation processing unit 73 converts the first target pinion angle θ calculated by the first conversion processing unit 71 into the output compensation value θ . p1 * Import.

[0107] The target pinion angle calculation unit 62 may be configured to omit at least one of the output compensation processing unit 73 and the residual current reduction processing unit 77. When the output compensation processing unit 73 is omitted, the addition processing unit 74 calculates the second target pinion angle θ calculated by the second conversion processing unit 72. p2 * When the second conversion processing unit 72 and the output compensation processing unit 73 are omitted, the addition processing unit 74 takes in the first target pinion angle θ calculated by the first conversion processing unit 71. p1 * When the residual current reduction processing unit 77 is omitted, the second target pinion angle θ calculated by the gradual change processing unit 76 is taken in. p2 * is the final target pinion angle θ p * becomes.

[0108] The driving assistance function may include, in addition to the parking assist function, a lane keep assist function, for example. The lane keep assist function assists the vehicle in staying in its lane by assisting the driver in steering when the vehicle is about to deviate from its lane. The driving assistance control device 45 sets a target pinion angle or an additional angle that is an angle to be added to the current target pinion angle as a command value for the vehicle to stay in the target lane.

[0109] In addition to the parking assist function, the driving assistance function includes a predicted trajectory line that indicates the expected path of the vehicle when moving forward, or the steering angle θ of the steered wheels 6. w The driving assistance control device 45 may include a guide function for displaying the pinion angle θ pa The driving assistance control device 45 can execute a guide monitor function in accordance with the steering state of the steering wheel 5.

[0110] The steering device 2 may have a clutch. In this case, the steering shaft 11 and the pinion shaft 21 are connected via the clutch. The clutch is, for example, an electromagnetic clutch that connects and disconnects power by turning on and off current to an exciting coil. The steering control device 1 executes an on / off control that switches the clutch on and off. When the clutch is disengaged, the power transmission between the steering wheel 5 and the steered wheels 6 is mechanically disconnected. When the clutch is engaged, the power transmission between the steering wheel 5 and the steered wheels 6 is mechanically connected.

[0111] The left and right steerable wheels 6 may be able to be steered independently of each other. In this case, the steering device 2 has two steering motors corresponding to the left and right steerable wheels 6. The steering control device 1 steers each steerable wheel 6 independently by controlling the steering motors corresponding to each steerable wheel 6. [Explanation of symbols]

[0112] 1...Steering control device 5...Steering wheel 6...Steering wheel 21 Pinion shaft (shaft) 22...Steering shaft 32...Steering motor 66...Adjustment processing unit (second processing unit) 73...output compensation processing unit (first processing unit) 75...Offset angle calculation unit (first processing unit) 77...residual current reduction processing section (first processing section) θ o1 …Offset angle θ p * …Target pinion angle (target angle) θ p …Pinion angle (actual angle) θ pa …Pinion angle for guide monitor (steering state quantity) θ s …Steering angle Δθ1: First change amount Δθ2: Second change amount Δθ3: Third change amount

Claims

1. 1. A steering control device that calculates a target angle of a shaft that rotates in conjunction with the steering operation of a steered wheel in accordance with a steering state of the steering wheel, in order to control power supply to a steering motor that generates a steering force for steering the steered wheels of a vehicle in which power transmission between the steering motor and the steering wheel is separated, and performs feedback control to make an actual angle follow the target angle, a first processing unit that executes a process for changing the target angle regardless of the steering state of the steering wheel; a second processing unit that calculates a steering state quantity for a guide monitor function to assist traveling of the vehicle by reducing or eliminating an influence that a change in the target angle by the first processing unit has on an actual angle of the shaft, A steering control device wherein the guide monitor function includes a function of displaying guide lines indicating the predicted course of the vehicle on a display of the vehicle, and the steering state quantity is used to execute the display of the guide lines.

2. 2. The steering control device according to claim 1, wherein the second processing unit calculates a change amount of the target angle accompanying the processing of the first processing unit, and calculates the steering state quantity by subtracting the change amount of the target angle from the actual angle of the shaft or the target angle based on the steering state of the steering wheel.

3. 3. The steering control device according to claim 1, wherein the processing of the first processing unit, when a vehicle power source is turned on, calculates an offset angle which is a deviation between a target angle calculated based on a current steering angle of the steering wheel and an actual angle of the shaft which reflects the actual steered state of the steered wheels, and executes a first change process which changes the value of the target angle by gradually changing the offset angle towards 0 by applying a gradual change process to the offset angle, and adding the offset angle after the gradual change process to the target angle.

4. 4. The steering control device according to claim 3, wherein the processing by the second processing unit includes processing for taking the offset angle that has been subjected to the gradual change processing as a first change amount, and calculating the steering state amount by subtracting the first change amount from an actual angle of the shaft or the target angle based on the steering state of the steering wheel.

5. 5. A steering control device according to claim 3 or 4, wherein the processing of the first processing unit further executes a second change process that changes the value of the target angle so that, when a steering shaft that steers the steered wheels moves to a position within a predetermined high axial force range, the position of the steering shaft deviates from the high axial force range toward a steering neutral position.

6. 6. The steering control device according to claim 5, wherein the processing of the second processing unit includes processing to take in the target angle before and after execution of the second change processing, calculate a second change amount by subtracting the target angle before execution of the second change processing from the target angle after execution of the second change processing, and calculate the steering state amount by subtracting the second change amount from an actual angle of the shaft or the target angle based on the steering state of the steering wheel.

7. A steering control device according to any one of claims 3 to 5, wherein the processing of the first processing unit further executes a third change process that changes the value of the target angle in order to reduce residual current generated in the steering motor.

8. 8. The steering control device according to claim 7, wherein the processing of the second processing unit includes processing to take in the target angle before and after execution of the third change processing, calculate a third change amount by subtracting the target angle before execution of the third change processing from the target angle after execution of the third change processing, and calculate the steering state amount by subtracting the third change amount from an actual angle of the shaft or the target angle based on the steering state of the steering wheel.

9. 9. The steering control device according to claim 1, wherein the steering state quantity is a rotation angle of a pinion shaft that meshes with a steering shaft that steers the steered wheels.

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