Steering control device

Abstract

A steering device (10) includes a steering shaft (31), a steering motor (32), and a control device (36), wherein the control device (36) controls the steering motor (32) so that the angle that can be converted into the steering angle of the steering wheel (12) follows the target angle calculated based on the steering state of the steering wheel (11). The control device (36) performs a correction process for correcting the target angle. The control device (36) corrects the target angle so that when the target angle increases toward the limit value of the angle range in either a vehicle stop state or an extremely low speed state, the degree of increase of the target angle becomes slower as the target angle approaches the limit value of the angle range.

Description

Technical Field

[0001] The invention relates to a steering control device for a vehicle. Background Art

[0002] There is a so-called wire-controlled steering device in which power transmission is separated between a steering wheel and a steering wheel. For example, a steering device described in Japanese Unexamined Patent Application Publication No. 2014-133521 (JP 2014-133521A) includes a reaction force motor, which is a source of a steering reaction force to be applied to a steering shaft, and a steering motor, which is a source of a steering force for steering the steering wheel. When the vehicle is running, a control device of the steering device generates a steering reaction force by controlling the power supply of the reaction force motor, and steers the steering wheel by controlling the power supply of the steering motor. Summary of the invention

[0003] Conventionally, in general steer-by-wire devices including the one in JP 2014-133521 A, when a driver operates a steering wheel, a steering wheel is steered while maintaining a force balance between a steering force generated by a steering motor and an axial force generated in a steering shaft.

[0004] However, in the case where an axial force exceeding the maximum steering force that the steering motor can generate is generated, it is difficult to maintain a force balance between the steering force generated by the steering motor and the axial force acting on the steering shaft according to the axial force characteristics of the vehicle. Therefore, there is a concern that it is difficult to smoothly steer the steering wheel according to the steering manipulation state of the steering wheel.

[0005] For example, in the case of a so-called static steering operation in which the steering wheel is turned while the vehicle is stopped, a high axial force is easily generated. However, depending on the axial force characteristics of the vehicle, the following phenomenon may occur. That is, the steering wheel does not move when the static steering operation is performed, and the steering wheel starts to move after the axial force decreases due to the start of the vehicle. There is a concern that the driver will feel unfamiliar with the occurrence of this phenomenon.

[0006] The present invention makes it possible to steer the steering wheel more smoothly.

[0007] One aspect of the present invention is a steering device. The steering device includes: a steering shaft configured to steer a steering wheel of a vehicle, wherein power transmission is separated between the steering shaft and the steering wheel; a steering motor configured to generate a steering force, which is a torque applied to the steering shaft to steer the steering wheel; and a control device configured to control the steering motor so that the angle that can be converted into the steering angle of the steering wheel follows the target angle calculated according to the steering state of the steering wheel. The control device is configured to perform the following correction processing: correcting the target angle so that the target angle is an angle within an angle region that can maintain force balance, which is a balance between the maximum steering force that the steering motor can generate and the axial force generated in the steering shaft. The control device is configured to correct the target angle so that when the target angle increases toward the limit value of the angle region in any state of the vehicle stopping state or the extremely low speed state, the degree of increase of the target angle becomes slower as the target angle approaches the limit value of the angle region.

[0008] Through the above configuration, the target angle is corrected so that the target angle is an angle within the angle region in which the force balance between the maximum steering force that the steering motor can generate and the axial force generated in the steering shaft can be maintained. Therefore, the target angle is prevented from falling outside the angle region in which the force balance between the steering force of the steering motor and the axial force generated in the steering shaft can be maintained. That is, the situation in which the axial force that exceeds the maximum steering force that the steering motor can generate can be avoided. Therefore, the steering wheel can be steered more smoothly according to the steering manipulation state of the steering wheel.

[0009] There is a concern that the driver may feel unfamiliar with the vehicle behavior associated with the execution of the target angle correction process. The unfamiliarity may be strong, especially in a vehicle stop state or at an extremely low speed state where large turns are likely to occur.

[0010] In this regard, with the above-mentioned steering control device, when the target angle increases toward the limit value of the angle region where it becomes difficult to maintain the force balance between the steering force and the axial force of the steering motor in a stopped state or an extremely low speed state of the vehicle, the target angle is corrected so that the degree of increase of the target angle becomes slower as the target angle approaches the limit value. Since the target angle changes more slowly toward the limit value, the driver's unfamiliarity with the behavior of the vehicle can be reduced.

[0011] In the steering device, the control device may be configured to set a limit value that limits the range of change of the target angle. The control device may be configured to set the limit value so that in any state of the vehicle being stopped or in an extremely low speed state, as the target angle increases, the ratio of the increase in the limit value relative to the increase in the target angle gradually decreases.

[0012] With the above configuration, the target angle can be corrected by limiting the target angle with the limit value.

[0013] In a steering control device, the control device can be configured to set a subtraction value to be subtracted from a target angle calculated based on a steering control state of a steering wheel, so that when the target angle increases toward a limit value of an angle area in either a vehicle stop state or an extremely low speed state, the degree of increase of the target angle becomes slower as the target angle approaches the limit value of the angle area.

[0014] With the above configuration, the target angle can be corrected by subtracting the subtraction value from the target angle. In the steering control device, when the limit value is a first limit value, the control device can be configured to limit the range of change of the target angle using a second limit value instead of the first limit value when the vehicle is not in any of a vehicle stop state or an extremely low speed state, the second limit value being a fixed value set based on a limit value of the angle region, and the control device can be configured to gradually change the first limit value or the second limit value over time by performing a gradient process on the first limit value or the second limit value.

[0015] With the above configuration, when the limit value for limiting the target angle is switched between the first limit value and the second limit value, the limit value for limiting the target angle is prevented from changing rapidly. Therefore, it is possible to prevent the target angle from changing rapidly.

[0016] In the steering device, in the case where the vehicle has an automatic driving control function, the control device may be configured not to perform correction processing regardless of the value of the vehicle speed when the automatic driving control function is in an on state.

[0017] When the automatic driving control is performed while the correction processing of the target angle is performed, there is a concern that the proper execution of the automatic driving control is hindered. In this regard, with the above configuration, when the automatic driving control function is in the on state, the correction processing of the target angle is not performed regardless of the value of the vehicle speed. Therefore, the correction processing of the target angle hinders the execution of the automatic driving control. In the case where the execution of the automatic driving control is required not to be hindered due to product specifications, etc., this requirement can be met.

[0018] In the steering control device, the control device can be configured not to perform correction processing regardless of the value of the vehicle speed when the vehicle speed state is abnormal, or when the gear is in the reverse gear range when the vehicle has a reverse guidance monitoring function to assist the vehicle's backward movement operation.

[0019] In the case of an abnormal vehicle speed state, when the correction process of the target angle is performed based on the abnormal vehicle speed, there is a concern that the correction process may give the driver a sense of unfamiliarity. In this regard, with the above configuration, in the case of an abnormal vehicle speed state, the correction process of the target angle is not performed regardless of the value of the vehicle speed. Therefore, it is possible to avoid giving the driver a sense of unfamiliarity.

[0020] In addition, depending on product specifications, etc., a reverse guidance monitoring function that assists the backward movement operation of the vehicle is provided in the vehicle. In the case where the backward movement operation of the vehicle is performed at an extremely low speed based on this function, the expected path line (expected trajectory line) of the vehicle displayed on the display in the car changes according to the vehicle speed due to the correction processing of the target angle performed during the backward movement operation, and there is a concern that the correction processing will give the driver a sense of unfamiliarity. In response to this, using the above-mentioned steering control device, when the gear position is in the reverse gear range, that is, when the backward movement operation of the vehicle is performed, the correction processing of the target angle is not performed regardless of the value of the vehicle speed. Therefore, it is possible to avoid giving the driver a sense of unfamiliarity.

[0021] By utilizing the steering control device of the present invention, the steering wheel can be steered more smoothly. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0023] Figure 1 is a configuration diagram showing an embodiment of a steering control device;

[0024] Figure 2 is a block diagram of a control device in an embodiment;

[0025] Figure 3 is a block diagram showing a part of a steering control unit in an embodiment; and

[0026] Figure 4 : is a graph showing the relationship between the target pinion angle and the limit value in the embodiment. DETAILED DESCRIPTION

[0027] The following will describe an implementation method for implementing the steering control device. Figure 1 As shown in FIG. 1 , the steering device 10 of the vehicle includes: a reaction force unit 20 that applies a steering reaction force to the steering wheel 11 of the vehicle; and a steering unit 30 that steers the steering wheel 12 of the vehicle. The steering reaction force is a torque that acts in the opposite direction to the direction in which the driver operates the steering wheel 11. By applying the steering reaction force to the steering wheel 11, the driver can be given a moderate hand response feeling.

[0028] The reaction force unit 20 includes a steering shaft 21 to which the steering wheel 11 is connected, a reaction force motor 22 , a speed reducer 23 , a rotation angle sensor 24 , a torque sensor 25 , and a reaction force control unit 27 .

[0029] The reaction force motor 22 is a source of the steering reaction force. For example, a three-phase brushless motor is used as the reaction force motor 22. The reaction force motor 22 is connected to the steering shaft 21 through a reducer 23. The torque generated by the reaction force motor 22 is applied to the steering shaft 21 as the steering reaction force.

[0030] The rotation angle sensor 24 is provided on the reaction force motor 22. The rotation angle sensor 24 detects the rotation angle θ of the reaction force motor 22. a The torque sensor 25 is provided at a portion between the speed reducer 23 and the steering wheel 11 on the steering shaft 21. The torque sensor 25 detects a steering torque T applied to the steering shaft 21 by a rotation operation of the steering wheel 11. h .

[0031] The reaction force control unit 27 detects the rotation angle θ of the reaction force motor 22 based on the rotation angle θ detected by the rotation angle sensor 24. a To calculate the steering angle θ s , the steering angle θ s The reaction force control unit 27 is based on the rotation angle θ of the reaction force motor 22 corresponding to the steering neutral position of the steering wheel 11. a The reaction force control unit 27 calculates the steering angle θ of the steering wheel 11 by calculating the integrated angle and multiplying the calculated integrated angle by a conversion factor based on the reduction ratio of the speed reducer 23. s , where the integrated angle is the rotation angle θ using the motor neutral point as the origin a The motor neutral point is stored in the reaction force control unit 27 as steering angle neutral point information.

[0032] The reaction force control unit 27 generates the steering torque T by driving the reaction force motor 22. h The reaction force control unit 27 controls the reaction force of the corresponding steering reaction force based on the steering torque T detected by the torque sensor 25. h The target steering reaction force is calculated, and based on the calculated target steering reaction force and the steering torque T h The target steering angle of the steering wheel 11 is calculated. The reaction force control unit 27 evaluates the rotation angle θ of the reaction force motor 22 based on the rotation angle θ of the reaction force motor 22. a The calculated steering angle θ s The reaction force control unit 27 uses the rotation angle θ of the reaction force motor 22 detected by the rotation angle sensor 24 to determine the difference between the reaction force motor 22 and the target steering angle and controls the supply of power to the reaction force motor 22 so that the difference is eliminated.a Vector control is performed on the reaction force motor 22 .

[0033] The steering unit 30 includes a steering shaft 31, a steering motor 32, a speed reducer 33, a pinion shaft 34, a rotation angle sensor 35, and a steering control unit 36. The steering shaft 31 extends in the vehicle width direction ( Figure 1 The left and right steering wheels 12 are connected to both ends of the steering shaft 31 through a tie rod 13.

[0034] The steering motor 32 is a source of steering force. For example, a three-phase brushless motor is used as the steering motor 32. The steering motor 32 is connected to the pinion shaft 34 through the reducer 33. The pinion teeth 34a of the pinion shaft 34 mesh with the rack teeth 31a of the steering shaft 31. The torque generated by the steering motor 32 is applied to the steering shaft 31 through the pinion shaft 34 as a steering force. The steering shaft 31 is rotated in the vehicle width direction ( Figure 1 By moving the steering shaft 31, the steering angle θ of the steering wheel 12 is changed. w .

[0035] The rotation angle sensor 35 is provided on the steering motor 32. The rotation angle sensor 35 detects the rotation angle θ of the steering motor 32. b The steering control unit 36 ​​performs steering control for steering the steering wheel 12 according to the steering operation state by driving control of the steering motor 32. The steering control unit 36 ​​performs steering control for steering the steering wheel 12 according to the steering operation state by driving control of the steering motor 32. b To calculate the pinion angle θ p , the pinion angle θ p is the rotation angle of the pinion shaft 34. In addition, the steering control unit 36 ​​calculates a target pinion angle as a target rotation angle of the pinion shaft 34 using the target steering angle calculated by the reaction force control unit 27. The target rotation angle of the pinion shaft 34 is calculated from the viewpoint of achieving a predetermined steering angle ratio. The steering control unit 36 ​​evaluates the difference between the target pinion angle of the pinion shaft 34 and the actual pinion angle θ. p The steering control unit 36 ​​uses the rotation angle θ of the steering motor 32 detected by the rotation angle sensor 35 to control the supply of power to the steering motor 32 so that the difference is eliminated. b To control the vector control of the steering motor 32.

[0036] Next, the reaction force control unit 27 will be described in detail. Figure 2 As shown, the reaction force control unit 27 includes a steering angle calculation unit 51 , a steering reaction force command value calculation unit 52 , and an energization control unit 53 .

[0037] The steering angle calculation unit 51 calculates the steering angle based on the rotation angle θ of the reaction force motor 22 detected by the rotation angle sensor 24. a To calculate the steering angle θ of the steering wheel 11 s The steering reaction force command value calculation unit 52 calculates the steering reaction force command value based on the steering torque T h and vehicle speed V to calculate the steering reaction force command value T * The steering reaction force command value calculation unit 52 calculates the steering reaction force command value T * , so that as the steering torque T h The larger the absolute value of and the lower the vehicle speed V, the greater the steering reaction force command value T * The steering reaction force command value calculation unit 52 will be described in detail later.

[0038] The energization control unit 53 provides the reaction force motor 22 with a steering reaction force command value T * Specifically, the energization control unit 53 generates the corresponding electric power based on the steering reaction force command value T * The current command value for the reaction force motor 22 is calculated. In addition, the energization control unit 53 detects the actual current I generated on the power supply path to the reaction force motor 22 through the current sensor 54 provided on the power supply path. a The current I a The value of is the value of the actual current supplied to the reaction force motor 22. Then, the energization control unit 53 evaluates the current command value and the actual current I a The deviation between the values ​​of and is controlled to supply power to the reaction force motor 22 so that the deviation is eliminated. As a result, the reaction force motor 22 generates a steering reaction force command value T * Corresponding torque. It can provide the driver with a moderate hand response feeling corresponding to the reaction force of the road surface.

[0039] Next, the steering control unit 36 ​​will be described in detail. Figure 2 As shown, the steering control unit 36 ​​includes 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 .

[0040] The pinion angle calculation unit 61 calculates the rotation angle θ of the steering motor 32 based on the rotation angle θ detected by the rotation angle sensor 35 . b To calculate the pinion angle θ p , the pinion angle θ p is the actual rotation angle of the pinion shaft 34. The steering motor 32 and the pinion shaft 34 are coordinated through the reducer 33. Therefore, at the rotation angle θ of the steering motor 32 b Angle θ with pinionp Using this correlation, the rotation angle θ of the steering motor 32 can be b Estimated pinion angle θ p In addition, the pinion shaft 34 meshes with the steering shaft 31. Therefore, at the pinion angle θ p There is a correlation between the pinion angle θ and the movement amount of the steering shaft 31. p is the steering angle θ of the steering wheel 12 w The value of .

[0041] The target pinion angle calculation unit 62 calculates the steering angle θ calculated by the steering angle calculation unit 51 based on the steering angle θ. s To calculate the target pinion angle θ p * In this embodiment, the target pinion angle calculation unit 62 calculates the target pinion angle θ p * Set to the steering angle θ s That is, as the steering angle θ s With steering angle θ w The ratio of the steering angle between them is "1:1".

[0042] The target pinion angle calculation unit 62 can calculate the target pinion angle θ p * Set to the steering angle θ s That is, the target pinion angle calculation unit 62 sets the steering angle θ according to the vehicle running state such as the vehicle speed V, for example. w and steering angle θ s The target pinion angle θ is calculated based on the steering angle ratio set. p * The target pinion angle calculation unit 62 calculates the target pinion angle θ p *, so that as the vehicle speed V decreases, the steering angle θ w Relative to the steering angle θ s The larger the vehicle speed V, the greater the steering angle θ w Relative to the steering angle θ s In order to achieve the steering angle ratio set according to the vehicle driving state, the target pinion angle calculation unit 62 calculates the steering angle θ s The correction angle is calculated by dividing the calculated correction angle by the steering angle θ according to the set steering angle ratio. s Add to calculate the target pinion angle θ p *.

[0043] The pinion angle feedback control unit 63 obtains the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * and the actual pinion angle θ calculated by the pinion angle calculation unit 61 p The pinion angle feedback control unit 63 is used to make the actual pinion angle θ p Follow the target pinion angle θ p * The pinion angle θ p The torque command value T for the torque generated by the steering motor 32 is calculated by the feedback control p * .

[0044] The power control unit 64 provides the steering motor 32 with a torque command value T p * Specifically, the energization control unit 64 controls the torque command value T p * to calculate the current command value for the steering motor 32. In addition, the energization control unit 64 detects the actual current I generated on the power supply path to the steering motor 32 through the current sensor 65 provided on the power supply path to the steering motor 32. b The current I b The value of is the value of the actual current supplied to the steering motor 32. Then, the energization control unit 64 evaluates the current command value and the actual current I b The deviation between the values ​​of and controls the supply of power to the steering motor 32 so that the deviation is eliminated. As a result, the steering motor 32 rotates in accordance with the torque command value T p *Corresponding angle.

[0045] In the steer-by-wire device 10, when the driver operates the steering wheel 11, the steered wheel 12 is steered while maintaining a force balance between the steering force generated by the steering motor 32 and the axial force acting on the steering shaft 31. However, when an axial force exceeding the maximum steering force that the steering motor 32 can generate is generated, it is difficult to maintain a force balance between the steering force generated by the steering motor 32 and the axial force acting on the steering shaft 31. Therefore, there is a concern that it is difficult to smoothly steer the steered wheel 12 according to the steering operation state of the steering wheel 11.

[0046] Therefore, in this embodiment, the following configuration is adopted as the steering control unit 36 ​​to enable the steering wheel 12 to steer more smoothly while avoiding the situation where an axial force exceeding the maximum steering force that the steering motor 32 can generate (hereinafter referred to as the "maximum output of the steering motor 32").

[0047] like Figure 2As shown by the two-dot chain line in FIG. 3 , the steering control unit 36 ​​includes a correction processing unit 66 . The correction processing unit 66 is provided on a calculation path between the target pinion angle calculation unit 62 and the pinion angle feedback control unit 63 .

[0048] The correction processing unit 66 corrects the target pinion angle θ calculated by the target pinion angle calculation unit 62 according to the axial force characteristics of the vehicle. p * , so that the final target pinion angle θ to be supplied to the pinion angle feedback control unit 63 p * This is an angle within an angular region in which the force balance between the maximum output of the steering motor 32 and the axial force can be maintained.

[0049] like Figure 3 As shown, the correction processing unit 66 includes a limit value calculation unit 71, a determination unit 72, a switching processing unit 73, a gradual change processing unit 74, and a protection processing unit 75. The limit value calculation unit 71 obtains the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * and the vehicle speed V detected by the vehicle speed sensor, and based on the acquired target pinion angle θ p * and vehicle speed V to calculate the target pinion angle θ p * The limit value of θ L1 Target pinion angle θ p * The range of variation is limited by the value θ L1 For example, the limit value θ L1 The limit value is set based on the angle, and the limit value enables the balance between the maximum output of the steering motor 32 and the axial force to be maintained according to the axial force characteristics of the vehicle when the vehicle speed V is a speed in the extremely low speed region. For example, the speed in the extremely low speed region is a speed equal to or lower than 5 km / h.

[0050] The steering force during static steering operation to steer the steering wheel 12 when the vehicle is stopped or the axial force when the steering wheel 12 is steered when the vehicle speed V is a speed in the extremely low speed region is much greater than the axial force when the steering wheel 12 is steered when the vehicle speed V is a speed exceeding the extremely low speed region. In other words, the axial force when the steering wheel 12 is steered when the vehicle speed V is a speed exceeding the extremely low speed region is much smaller than the axial force when the steering wheel 12 is steered when the vehicle speed is a speed in the extremely low speed region.

[0051] The limit value calculation unit 71 uses the target pinion angle θ defined p * With the limit value θ L1The mapping between the relationship between L1 For example, the mapping is set from the viewpoint that when the vehicle is stopped or when the vehicle speed V is in an extremely low speed region, the target pinion angle θ is set to p * The angle is limited to an angle within an angle region capable of maintaining a force balance between the maximum output of the steering motor 32 and the axial force according to the axial force characteristics of the vehicle.

[0052] like Figure 4 As shown in FIG. 1 , the characteristics of the mapping ML are as follows. That is, as shown by the characteristic line L1, as the target pinion angle θ p * The absolute value of increases from "0", the limit value θ L1 Direction limit value θ L1 The maximum value of θ max However, as the target pinion angle θ p * The absolute value of the limit value θ increases L1 The increase in the target pinion angle θ p * The rate of increase of the absolute value of (the slope of the characteristic line L1) gradually decreases. That is, as the target pinion angle θ increases p * The absolute value of the limit value θ increases L1 The increase in the target pinion angle θ p * The absolute value of θ increases gradually. max The maximum value θ is set based on the limit value of the angle that enables the balance between the maximum output of the steering motor 32 and the axial force to be maintained according to the axial force characteristics of the vehicle. max V is set according to vehicle speed.

[0053] As shown by the characteristic line L0, with the limit value θ L1 Relative to the target pinion angle θ p * The absolute value of the linear increase increases compared to the limit value θ L1 With the target pinion angle θ p * The absolute value of increases slowly, and then the limit value θ L1 Reaching the maximum value θ max .

[0054] The determination unit 72 determines whether the current situation is the limit value θ calculated by the limit value calculation unit 71. L1 The situation or limit value θ that should be enabled L1Situations where the vehicle should be disabled. The determination unit 72 acquires a vehicle speed state signal S1 as a state variable reflecting the driving state of the vehicle, which is an electrical signal of a vehicle speed state indicating whether the vehicle speed V detected by the vehicle speed sensor is normal. For example, when an abnormality or failure of the vehicle speed sensor is detected, it is determined that the vehicle speed V is abnormal. In addition, the determination unit 72 acquires a gear state signal S2 as an electrical signal indicating the current gear of the vehicle. The gear state signal S2 is used to determine whether to perform a backward movement operation of the vehicle. In addition, the determination unit 72 acquires an automatic driving state signal S3 as an electrical signal indicating whether the automatic driving control function is in an on state or an off state. In addition to driving assistance control functions such as a parking assistance function, the automatic driving control function also includes an automatic driving control function that allows autonomous driving without steering manipulation being performed by the driver.

[0055] The determination unit 72 sets the value of the flag F based on the vehicle state signal S1, the gear state signal S2, and the automatic driving state signal S3. Specifically, when it is determined that all three conditions (a), (b), and (c) described below are satisfied, the determination unit 72 sets the value of the flag F to "1". In addition, when it is determined that at least one of the three conditions (a), (b), and (c) is not satisfied, the determination unit 72 sets the value of the flag F to "0".

[0056] (a) The operating status of the automatic driving control function is not the on state.

[0057] (b) The gear position is not within the reverse gear range (R range).

[0058] (c) The vehicle speed is normal.

[0059] The switching processing unit 73 obtains the limit value θ calculated by the limit value calculation unit 71. L1 and the limit value θ which is a fixed value stored in the storage device of the steering control unit 36 L0 . Limit value θ L0 The limit value θ is set based on an angle that enables the balance between the maximum output of the steering motor 32 and the axial force to be maintained according to the axial force characteristics of the vehicle. L0 can be set to the maximum value θ above max Same value.

[0060] The switching processing unit 73 selects the limit value θ according to the value of the flag F set by the determination unit 72. L1 and the limit value θ L0 One of them is used as the pre-limit value θ L2 When the value of the flag F is "1", the switching processing unit 73 selects the limit value θ L1 As the pre-limit value θ L2When the value of the flag F is "0", the switching processing unit 73 selects the limit value θ L0 As the pre-limit value θ L2 .

[0061] The gradual change processing unit 74 obtains the pre-limit value selected by the switching processing unit 73 θL2 The gradual change processing unit 74 performs the following steps for the pre-limit value θ L2 Gradual change over time, i.e., to gradually change the pre-limit value θ over time L2 To calculate the final limit value θ L3 A low-pass filter may be used as the gradient processing unit 74 .

[0062] The protection processing unit 75 obtains the target pinion angle θ calculated by the target pinion angle calculation unit 62. p * and the final limit value θ calculated by the gradient processing unit 74 L3 The protection processing unit 75 is based on the final limit value θ L3 Execute the target pinion angle θ p * That is, the protection processing unit 75 sets the target pinion angle θ p * The absolute value and limit value θ L3 At the target pinion angle θ p * The absolute value is greater than the limit value θ L3 In the case of p * The absolute value of is limited to the limit value θ L3 Target pinion angle θ after limiting processing p * The final target pinion angle θ is taken as p * Supplied to the pinion angle feedback control unit 63. At the target pinion angle θ p * The absolute value is equal to or less than the limit value θ L3 In the case of a value of p * As the final target pinion angle θ p * Supplied to the pinion angle feedback control unit 63.

[0063] With this embodiment, the effects described below can be obtained. Target pinion angle θ p *is corrected so that the target pinion angle θ p * It is an angle within the angle region where the force balance between the maximum output of the steering motor 32 and the axial force can be maintained according to the axial force characteristics of the vehicle. p * The angle region where it is difficult to maintain the force balance between the steering force and the axial force of the steering motor, that is, to avoid the target pinion angle θ p * The angle at which it is difficult to smoothly steer the steered wheel 12 is thus avoided. Therefore, it is possible to avoid the situation where an axial force exceeding the maximum steering force that the steering motor 32 can generate is generated. Therefore, the steered wheel 12 can be smoothly steered according to the steering operation state of the steering wheel 11.

[0064] Worried about the driver's deviation from the target pinion angle θ p * The vehicle behavior associated with the execution of the correction process may feel strange. The strangeness may be strong, especially in a stopped state or an extremely low speed state where a large turn is likely to occur. In this regard, in the present embodiment, when the vehicle is stopped or at an extremely low speed, as the target pinion angle θ p * The absolute value of the limit value θ increases L1 The increase in the target pinion angle θ p * The absolute value of θ increases with a gradient that becomes more gradual. Therefore, by limiting the value θ L1 Limit target pinion angle θ p * The absolute value of MAX Therefore, the driver's unfamiliarity with the vehicle's behavior can be reduced.

[0065] The switching processing unit 73 selects the limit value θ calculated by the limit value calculation unit 71 in the extremely low speed region. L1 As the pre-limit value θ L2 , in the case of the medium speed area or the high speed area, the limit value θ is selected as a fixed value L0 As the pre-limit value θ L2 That is, the pre-limit value θ L2 Depends on the vehicle speed within the limit value θ L1 With the limit value θ L0 In this case, depending on the target pinion angle θ p * The value of the limit value θ L1 With the limit value θ L0 There may be a large difference between them. In this case, there is a concern that due to the pre-limit value θ L2The rapid change of the final target pinion angle θ p * The value of changes rapidly. In this regard, in the present embodiment, the pre-limit value θ selected by the switching processing unit 73 is L2 Perform a gradual change. Therefore, at the pre-limited value θ L2 At the limit value θ L1 With the limit value θ L0 In the case of switching between L2 The rapid change of the final target pinion angle θ p * Rapid changes in the value of .

[0066] Depending on product specifications, etc., it is required that the execution of the autonomous driving control is not hindered when the autonomous driving control function is in the on state. That is, the control device for the autonomous driving control sets the additional angle, which is the angle to be added to the target pinion angle or the current target pinion angle, as a command value for causing the vehicle to travel in the target lane, for example. In this case, when the vehicle is driven based on the mapping M L The limit value of θ L1 is selected as the pre-limit value θ L2 When the target pinion angle set by the control device for the automatic driving control is based on the mapping M L The limit value of θ L1 In this regard, in a case where the operation state of the automatic driving control function is the on state, the determination unit 72 determines that the current situation is the limit value θ calculated by the limit value calculation unit 71. L1 Therefore, when the automatic driving control function is in the on state, even if the vehicle speed V is in the extremely low speed range, the automatic driving control function based on the map M is not executed. L The limit value of θ L1 The restriction process is applied to the target pinion angle θ p * This can avoid hindering the execution of autonomous driving control.

[0067] When the vehicle speed state is abnormal, the use of the restriction value θ is performed based on the abnormal vehicle speed V. L1 In this regard, when the vehicle speed state is abnormal, the determination unit 72 determines that the current situation is the limit value θ calculated by the limit value calculation unit 71. L1 Therefore, when the vehicle speed state is abnormal, even if the vehicle speed V is in the extremely low speed range, the control based on the map M is not performed. L The limit value of θ L1 The restriction process is applied to the target pinion angle θp * This can avoid giving the driver a sense of unfamiliarity.

[0068] In some cases, a so-called back-up guidance monitoring function is provided according to product specifications or the like. The back-up guidance monitoring function is a function that assists a back-up movement operation of a vehicle as exemplified by parking in a garage and parallel parking by attaching a camera device to the rear and displaying an image captured by the camera device and an expected path line (expected trajectory line) of the vehicle on a display in the vehicle compartment. In the case where a back-up movement operation is performed in an extremely low speed area based on this function, the back-up movement operation is performed using the limit value θ. L1 When the restriction processing is performed, the expected path line of the vehicle and the like change according to the vehicle speed V, and there is a concern that the restriction processing may give the driver a sense of unfamiliarity. In this regard, when the gear position is in the reverse range, that is, when the vehicle is moving backward, the determination unit 72 determines that the current situation is the restriction value θ calculated by the restriction value calculation unit 71. L1 Therefore, when the gear is in the reverse range, even if the vehicle speed V is a speed in the extremely low speed region, the control is not performed by using the mapping M. L The limit value of θ L1 The restriction process is applied to the target pinion angle θ p * This can avoid giving the driver a sense of unfamiliarity.

[0069] Other Implementations

[0070] This embodiment can be performed when modified as follows. In this embodiment, the target pinion angle θ calculated by the target pinion angle calculation unit 62 is p * By being finally limited to the value θ L3 However, the target pinion angle θ p * It can be corrected as follows. That is, the target pinion angle θ calculated by the target pinion angle calculation unit 62 is p * For example, in the extremely low speed region, the target pinion angle θ calculated by the target pinion angle calculation unit 62 is shifted according to the vehicle speed. p * Subtract the value θ from off , to obtain Figure 4 The limit value θ shown by the characteristic line L1 in the curve diagram L1 For the target pinion angle θ p * The change characteristics are the same as those of (see expression (1)). Subtract the value θ offAccording to the target pinion angle θ calculated by the target pinion angle calculation unit 62 p * And changes.

[0071] θ p * (final) = θ p * -θ off (1)

[0072] In this embodiment, the determination unit 72 determines whether the current situation is the limit value θ calculated by the limit value calculation unit 71 based on whether the above three conditions (a), (b), and (c) are satisfied. L1 The situation or limit value θ that should be enabled L1 The situation that should be disabled, but the determination is not limited to this. For example, one or two of the three conditions (a), (b) and (c) can be adopted, and the determination can be performed based on whether these conditions are met. Even in this case, the consistent effect corresponding to the embodiment can be obtained.

[0073] Depending on product specifications, etc., a configuration not including the gradual change processing unit 74 may be adopted as the correction processing unit 66. The reaction force control unit 27 and the steering control unit 36 ​​may constitute a single control device.

[0074] In the embodiment, a so-called connector-less structure in which power transmission is separated between the steering shaft 21 and the steering wheel 12 is adopted as the steering device 10 of the vehicle. However, a structure in which power transmission can be separated between the steering shaft 21 and the steering wheel 12 by a clutch may be adopted. When the clutch is disconnected, power transmission is separated between the steering wheel 11 and the steering wheel 12. When the clutch is connected, power transmission is performed between the steering wheel 11 and the steering wheel 12.

Claims

1. A steering control device (10), characterized in that include: A steering shaft (31) configured to steer a steering wheel (12) of a vehicle, wherein power transmission between the steering shaft (31) and the steering wheel (11) is separated; a steering motor (32) configured to generate a steering force, wherein the steering force is a torque applied to the steering shaft (31) to steer the steering wheel (12); and A control device (36) is configured to control the steering motor (32) so that the angle that can be converted into the steering angle of the steering wheel (12) follows the target angle calculated according to the steering manipulation state of the steering wheel (11), wherein: The control device (36) is configured to perform the following correction processing: correcting the target angle so that the target angle is an angle within an angle region capable of maintaining a force balance, the force balance being a balance between a maximum steering force that can be generated by the steering motor (32) and an axial force generated in the steering shaft (31); and The control device (36) is configured to correct the target angle so that when the target angle increases toward the limit value of the angle range in either a vehicle stop state or an extremely low speed state, the increase degree of the target angle becomes slower as the target angle approaches the limit value of the angle range, The control device (36) is configured not to execute the correction process regardless of the value of the vehicle speed when the vehicle speed state is abnormal.

2. The steering control device (10) according to claim 1, characterized in that: The control device (36) is configured to set a limit value that limits the range of change of the target angle; as well as The control device (36) is configured to set the limit value so that in either the vehicle stop state or the extremely low speed state, as the target angle increases, a ratio of an increase in the limit value relative to an increase in the target angle gradually decreases.

3. The steering control device (10) according to claim 1, characterized in that: The control device (36) is configured to set a subtraction value to be subtracted from a target angle calculated based on the steering operation state of the steering wheel (11), so that when the target angle increases toward a limit value of the angle area in either the vehicle stop state or the extremely low speed state, the degree of increase of the target angle becomes slower as the target angle approaches the limit value of the angle area.

4. The steering control device (10) according to claim 2, characterized in that: When the limiting value is a first limiting value, the control device (36) is configured to use a second limiting value instead of the first limiting value to limit the range of change of the target angle when the vehicle is not in either the vehicle stop state or the extremely low speed state, wherein the second limiting value is a fixed value set based on the limit value of the angle area, and the control device (36) is configured to gradually change the first limiting value or the second limiting value over time by performing a gradient process on the first limiting value or the second limiting value.

5. The steering device (10) according to any one of claims 1 to 4, characterized in that: In the case where the vehicle has an automatic driving control function, the control device (36) is configured not to perform the correction process regardless of the value of the vehicle speed when the automatic driving control function is in an on state.

6. The steering device (10) according to claim 5, characterized in that: The control device (36) is configured not to perform the correction processing regardless of the value of the vehicle speed when the vehicle speed state is abnormal or when the gear position is in the reverse range in the case where the vehicle has a reverse guidance monitoring function that assists the backward movement operation of the vehicle.

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