Steering control device

Abstract

To provide a steering control device capable of restraining the magnitude of a change speed of a target steering equivalent angle from becoming excessively large or small.SOLUTION: The PU sets the target steered corresponding angle θ p * 0 in accordance with the steering angle as an input variable. A PU calculates an offset amount which is a difference between a target turning corresponding angle θ p * 0 and a turning corresponding angle θ p by using a predetermined condition that the target turning corresponding angle θ p * 0 changes discontinuously as a trigger. The PU calculates a target turning corresponding angle θ p * by subtracting an offset correction amount Δ θ p corresponding to the offset amount from the target turning corresponding angle θ p * 0. The PU changes the rate of decrease in the magnitude of the offset correction amount Δ θ p depending on whether the sign of the offset correction amount Δ θ p matches the sign of the rate of change in the target corresponding steered angle θ p * 0.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] For example, Patent Document 1 listed below describes a steering control device for a system in which the transmission of power between the steering wheel and the steered wheels is interrupted. Under predetermined conditions, this device corrects the target value of the steered angle of the steered wheels in accordance with the difference between the target value and the actual steered angle, and then gradually changes the correction amount to zero. This device sets the speed of the gradual change in accordance with the vehicle speed and the steering angular velocity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-37763 Summary of the Invention [Problem to be solved by the invention]

[0004] By changing the gradual-change speed in accordance with the vehicle speed and angular velocity as described above, it is possible to reduce the driver's discomfort in steering compared to when the gradual-change speed is fixed. However, the driver's impression of the gradual-change process may differ depending on whether the driver's steering direction and the direction of the gradual change coincide with each other. [Means for solving the problem]

[0005] The means for solving the above problems and their effects will be described below. 1. A system is configured to execute a target steering equivalent angle setting process, an operation process, an offset amount calculation process, an offset compensation process, a judgment process, and an offset reduction process in a state where the steered wheels and the steering shaft are mechanically disconnected, the target steering equivalent angle setting process is a process for setting a target steering equivalent angle in response to a steering request, the target steering equivalent angle is a target value of the steering equivalent angle which is a variable indicating the steering angle of the steered wheels, the operation process is a process for operating a motor which turns the steered wheels in response to an operation amount of control in which the target steering equivalent angle is a target value of a control amount, and the offset amount calculation process is a process for calculating the target steering equivalent angle relative to the actual steering equivalent angle when a predetermined condition is met as a trigger the offset compensation process is a process of subtracting and correcting the target steering equivalent angle as an input variable of the operation process by an offset correction amount corresponding to the offset amount, the determination process is a process of determining whether or not a sign of a steering angular velocity variable and a sign of the offset correction amount match, the steering angular velocity variable is a variable indicating a rate of change of the target steering equivalent angle, and the offset reduction process is a process of reducing the magnitude of the offset correction amount, and includes a process of setting a rate of reduction of the magnitude of the offset correction amount to a larger value when it is determined by the determination process that the two do not match than when it is determined that they do.

[0006] When the offset reduction process is performed, the target steering equivalent angle changes as the magnitude of the offset correction amount decreases. Therefore, the magnitude of the rate of change of the target steering equivalent angle is affected by the offset reduction process. In particular, this effect differs depending on whether the sign of the rate of change of the target steering equivalent angle set by the target steering equivalent angle setting process matches the sign of the offset correction amount. That is, when the sign of the rate of change of the target steering equivalent angle set by the target steering equivalent angle setting process matches the sign of the offset correction amount, the magnitude of the rate of change of the target steering equivalent angle is increased. This is because the decrease in the magnitude of the offset correction amount acts to amplify the change in the set target steering equivalent angle. On the other hand, when the sign of the rate of change of the target steering equivalent angle set by the target steering equivalent angle setting process is opposite to the sign of the offset correction amount, the magnitude of the rate of change of the target steering equivalent angle is suppressed. This is because the decrease in the magnitude of the offset correction amount acts to cancel out the change in the set target steering equivalent angle.

[0007] Therefore, for example, if the decrease rate of the offset correction amount is adapted to an appropriate value when the signs are the same, the magnitude of the change rate of the target turning equivalent angle may be excessively small when the signs are opposite. Also, for example, if the decrease rate of the offset correction amount is adapted to an appropriate value when the signs are opposite, the magnitude of the change rate of the target turning equivalent angle may be excessively large when the signs are the same.

[0008] Therefore, in the above configuration, the rate of decrease in the magnitude of the offset correction amount is set to a larger value when the signs match compared to when they do not match, thereby making it possible to prevent the magnitude of the change rate of the target steering equivalent angle from becoming excessively large or small due to the execution of the offset reduction process.

[0009] 2. A steering control device as described in 1 above, wherein the offset reduction processing includes angular velocity sensitive processing, and the angular velocity sensitive processing is processing that changes the reduction rate in accordance with the rate of change, under the condition that the reduction rate when the magnitude of the rate of change of the target steering equivalent angle is large is equal to or greater than the reduction rate when the magnitude of the rate of change is small.

[0010] When the magnitude of the rate of change of the target steering equivalent angle set by the target steering equivalent angle setting process is large, there is a high possibility that a steering request has been made to change the steering angle early. Therefore, by employing the angular velocity sensitive process, when the magnitude of the rate of change of the target steering equivalent angle is large, it is possible to more quickly bring the value of the input variable of the operation process closer to the target steering equivalent angle set by the target steering equivalent angle setting process than when the magnitude of the rate of change of the target steering equivalent angle is small.

[0011] However, in this case, if the reduction rate of the offset correction amount is determined regardless of the sign, for example, when a steering request for an early change in the steering angle is made, inconveniences such as a delay in the change in the steering angle occur. In other words, when the sign is reversed, the reduction in the magnitude of the offset correction amount acts to cancel out the change in the set target steering equivalent angle, so that increasing the reduction rate actually suppresses the change in the target steering equivalent angle.

[0012] Therefore, in the above configuration, the process of setting the reduction rate based on the determination result of the determination process is particularly useful. 3. A steering control device as described in 2 above, which is provided with a storage device that stores angular velocity sensitive regulation data, wherein the angular velocity sensitive processing is executed using the angular velocity sensitive regulation data, wherein the angular velocity sensitive regulation data is map data in which a steering angular velocity variable is an input variable and a reduction variable is an output variable, and which consists of separate data corresponding to whether or not the judgment result of the judgment processing indicates a match, wherein the steering angular velocity variable is a variable indicating the rate of change of the target steering equivalent angle, and the reduction variable is a variable indicating the rate of reduction.

[0013] In the above configuration, the angular velocity sensitive regulation data is separate data depending on whether the judgment result of the judgment process is a match or not, so the rate at which the magnitude of the offset correction amount decreases can be appropriately determined depending on whether the result is a match or not.

[0014] 4. A steering control device as described in 2 above, wherein the offset reduction processing is a processing that reduces the magnitude of the offset correction amount in accordance with the reduction rate set by the angular velocity sensitive processing when the judgment result of the judgment processing is either a match or a mismatch, and that reduces the magnitude of the offset correction amount in accordance with the value obtained by multiplying the reduction rate set by the angular velocity sensitive processing by a gain when the judgment result of the judgment processing is the other of the two.

[0015] In the above configuration, the decrease rate can be set to an appropriate value for each of the match and mismatch cases by the simple process of multiplying the gain when the determination result is a match or a mismatch.

[0016] 5. A steering control device described in any one of 1 to 4 above, which is provided with a storage device that stores vehicle speed sensitive regulation data, wherein the offset reduction process includes vehicle speed sensitive processing, which is defined by the vehicle speed sensitive regulation data and is a process that changes the reduction rate according to the vehicle speed as an input variable, and the vehicle speed sensitive regulation data consists of separate data corresponding to whether or not the judgment result of the judgment process indicates a match.

[0017] In the above configuration, the vehicle speed sensitive regulation data is different data depending on whether the judgment result of the judgment process is a match or not, so that the rate at which the magnitude of the offset correction amount is reduced can be appropriately determined depending on whether the result is a match or not.

[0018] 6. A steering control device described in any one of 1 to 5 above, configured to perform an identification process, wherein the identification process is a process for identifying steering in and steering back, and the offset reduction process includes a process for changing the rate at which the magnitude of the offset correction amount is reduced between steering in and steering back, even if the judgment results of the judgment process are consistent.

[0019] In the above configuration, by changing the speed of decrease between turning the steering wheel and returning the steering wheel, the steering feel can be set more finely than when the speed of decrease is set to the same for turning the steering wheel and returning the steering wheel. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a diagram showing a configuration of a vehicle according to a first embodiment. [Figure 2] FIG. 2 is a block diagram showing part of the processing executed by the steering control device shown in FIG. [Figure 3] 2 is a flowchart showing a procedure of processing executed by the steering control device shown in FIG. [Figure 4] FIG. 4 is a diagram showing map data used in the processing shown in FIG. 3. [Figure 5] 4(a) and 4(b) are time charts showing the effect of the processing shown in FIG. 3. [Figure 6] 6 is a flowchart showing the procedure of processing executed by a steering control device according to a second embodiment. [Figure 7] 10 is a flowchart showing the procedure of processing executed by a steering control device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] First Embodiment The first embodiment will be described below with reference to the drawings. "Configuration of steering control system" As shown in Fig. 1, vehicle steering device 10 is a steer-by-wire type steering device. Steering device 10 includes a reaction force actuator Ar and a turning actuator At. Steering device 10 of this embodiment has a structure in which the power transmission path between steering wheel 12 and steered wheels 44 is mechanically disconnected.

[0022] A steering shaft 14 is connected to the steering wheel 12. The reaction force actuator Ar is an actuator for applying a steering reaction force to the steering wheel 12. The steering reaction force is a force that acts in the opposite direction to the direction of operation of the steering wheel 12 by the driver. By applying the steering reaction force to the steering wheel 12, it is possible to give the driver an appropriate sense of responsiveness. The reaction force actuator Ar includes a reduction mechanism 16, a reaction force motor 20, and a reaction force inverter 22.

[0023] Reaction motor 20 is, for example, a three-phase brushless motor. The rotation shaft of reaction motor 20 is connected to steering shaft 14 via speed reducer 16. Meanwhile, steered shaft 40 extends along the vehicle width direction, which is the left-right direction in FIG. 1. Left and right steered wheels 44 are connected to both ends of steered shaft 40 via tie rods 42, respectively. The steered angle of steered wheels 44 is changed by linear movement of steered shaft 40.

[0024] Steering actuator At includes speed reduction mechanism 56, steering motor 60, and steering inverter 62. Steering motor 60 is, as an example, a three-phase surface permanent magnet synchronous motor. The rotating shaft of steering motor 60 is connected to pinion shaft 52 via speed reduction mechanism 56. Pinion teeth of pinion shaft 52 mesh with rack teeth 54 of steering shaft 40. Rack-and-pinion mechanism 50 is formed by pinion shaft 52 and steering shaft 40, on which rack teeth 54 are provided. Torque of steering motor 60 is applied as a steering force to steering shaft 40 via pinion shaft 52. In response to the rotation of steering motor 60, steering shaft 40 moves along the vehicle width direction, which is the left-right direction in FIG. 1 .

[0025] The steering control device 70 includes a PU 72 and a storage device 74. The PU 72 is a software processing device such as a CPU or a GPU. The storage device 74 may be an electrically non-rewritable non-volatile memory. Alternatively, the storage device 74 may be an electrically rewritable non-volatile memory or a storage medium such as a disk medium. The steering control device 70 controls the control amount by the PU 72 executing a program stored in the storage device 74.

[0026] The control object of steering control device 70 is steering wheel 12. Steering control device 70 operates reaction force actuator Ar to control the steering reaction force as the control amount of the control object. Fig. 1 shows an operation signal MSs to reaction force inverter 22. Furthermore, the control object of steering control device 70 is steered wheels 44. Steering control device 70 operates steering actuator At to control the steering angle of steered wheels 44 as the control amount of the control object. Fig. 1 shows an operation signal MSt to steering inverter 62.

[0027] In order to control the control variable, steering control device 70 refers to steering torque Th, which is input torque to steering shaft 14, detected by torque sensor 80. Steering control device 70 also refers to rotation angle θa of the rotation shaft of reaction force motor 20, detected by rotation angle sensor 82. Steering control device 70 also refers to currents iu1, iv1, iw1 flowing through reaction force motor 20. Currents iu1, iv1, iw1 are quantified as voltage drops across shunt resistors provided in each leg of reaction force inverter 22. Steering control device 70 also refers to rotation angle θb of the rotation shaft of turning motor 60, detected by rotation angle sensor 84. Steering control device 70 also refers to currents iu2, iv2, iw2 flowing through turning motor 60. Currents iu2, iv2, iw2 are quantified as voltage drops across shunt resistors provided in each leg of turning inverter 62. The steering control device 70 also refers to the vehicle speed V detected by the vehicle speed sensor 92 .

[0028] "control" FIG. 2 shows part of the processing executed by the steering control device 70. The steering angle calculation process M10 is a process for calculating a steering angle θh, which is the rotation angle of the steering wheel 12, based on the rotation angle θa as an input variable. The steering angle calculation process M10 includes a process for converting the rotation angle θa into an integrated angle including a range exceeding 360°, for example, by counting the number of rotations of the reaction force motor 20 from a steering neutral position, which is the position of the steering wheel 12 when the vehicle is traveling straight. The steering angle calculation process M10 includes a process for calculating the steering angle θh by multiplying the integrated angle obtained by conversion by a conversion coefficient based on the rotational speed ratio of the speed reduction mechanism 16. Note that the steering angle θh may be set to a positive value when the steering angle is to the right of the steering neutral position, and a negative value when the steering angle is to the left of the steering neutral position, for example.

[0029] The steering equivalent angle calculation process M12 is a process for calculating the steering equivalent angle θp based on the rotation angle θb as an input variable. The steering equivalent angle θp is a variable that indicates the steering angle of the steered wheels 44. The steering equivalent angle calculation process M12 includes, for example, a process for counting the number of rotations of the steering motor 60 from a rack neutral position, which is the position of the steering shaft 40 when the vehicle is traveling straight, and converting the counted number of rotations into an integrated angle that includes a range exceeding 360°. The steering equivalent angle calculation process M12 includes a process for multiplying the converted integrated angle by a conversion coefficient based on the rotational speed ratio of the reduction mechanism 56 to calculate the steering equivalent angle θp. That is, in this embodiment, as an example, the steering equivalent angle θp is set to a value equal to the actual rotation angle of the pinion shaft 52. Note that the steering equivalent angle θp may be set to a positive value when the angle is to the right of the rack neutral position and a negative value when the angle is to the left of the rack neutral position.

[0030] Target reaction force calculation process M14 is a process for calculating target reaction force Tr* corresponding to the steering reaction force to be applied to steering wheel 12, based on input variables such as steering torque Th, vehicle speed V, steering equivalent angle θp, and q-axis current iqt. Here, q-axis current iqt is the q-axis current flowing to steering motor 60. q-axis current iqt is a variable indicating the torque of steering motor 60. q-axis current iqt is calculated by PU 72 based on currents iu2, iv2, iw2 and rotation angle θb. More specifically, target reaction force calculation process M14 includes a process for changing target reaction force Tr* in accordance with the magnitude of the torque of steering motor 60 under the following condition. This condition is a condition that the magnitude of target reaction force Tr* when the torque of steering motor 60 is large is equal to or greater than the magnitude of target reaction force Tr* when the torque of steering motor 60 is small. Furthermore, the target reaction force calculation process M14 includes a process for changing the target reaction force Tr* in accordance with the steering equivalent angle θp as an input variable under the following condition: The condition is that the magnitude of the target reaction force Tr* when the steering equivalent angle θp is large is equal to or greater than the magnitude of the target reaction force Tr* when the steering equivalent angle θp is small.

[0031] The target reaction force Tr* is actually a command value for the reaction force motor 20. The value obtained by multiplying the target reaction force Tr* by a coefficient according to the reduction ratio of the reduction mechanism 16 is the steering reaction force. In the description "changing B according to A on the condition that B when A is large is equal to or larger than B when A is small," the case where A is large and the case where A is small refer to the relative relationship of magnitude when comparing the two. For example, "when A is large" corresponds to the case where "A is a first value," and "when A is small" corresponds to the case where "A is a second value smaller than the first value." The above description also means that, depending on the settings of the first and second values, B when A is the first value may be larger than B when A is the second value. The above description also means that B is changed according to A so that A when B is large is larger than A when B is small.

[0032] The reaction force operation process M16 is a process for outputting an operation signal MSs for the reaction force inverter 22 based on input variables such as target reaction force Tr*, currents iu1, iv1, iw1, and rotation angle θa. The reaction force operation process M16 includes a process for calculating dq-axis current command values ​​based on the target reaction force Tr*. The reaction force operation process M16 also includes a process for calculating dq-axis currents based on the currents iu1, iv1, iw1 and rotation angle θa. The reaction force operation process M16 then includes a process for calculating an operation signal MSs for operating the reaction force inverter 22 so that the dq-axis currents approach the command values.

[0033] The target steering equivalent angle setting process M18 is a process for calculating a target steering equivalent angle θp*0 based on the steering angle θh and vehicle speed V as input variables. The target steering equivalent angle θp*0 is a target value of the steering equivalent angle θp according to the operation of the steering wheel 12 by the driver. The target steering equivalent angle setting process M18 includes a process for changing the target steering angle ratio, which is the ratio between the steering angle θh and the target steering equivalent angle θp*0, according to the vehicle speed V, etc.

[0034] The offset correction amount calculation process M20 is a process for calculating the offset correction amount Δθp of the target turning equivalent angle θp*0. The offset correction process M22 is a process for calculating the target turning equivalent angle θp* by subtracting the offset correction amount Δθp from the target turning equivalent angle θp*0.

[0035] The steering feedback process M24 is a process for calculating the steering torque command value Tt*, which is the command value of the torque of the steering motor 60, in accordance with the operation amount of the feedback control in which the steering equivalent angle θp is the control amount and the target steering equivalent angle θp* is the target value of the control amount.

[0036] The steering operation process M26 is a process for outputting an operation signal MSt for the steering inverter 62 based on the input variables of the steering torque command value Tt*, currents iu2, iv2, iw2, and rotation angle θb. The steering operation process M26 includes a process for calculating dq-axis current command values ​​based on the steering torque command value Tt*. The steering operation process M26 also includes a process for calculating dq-axis currents based on the currents iu2, iv2, iw2 and the rotation angle θb. The steering operation process M26 then includes a process for calculating an operation signal MSt for operating the steering inverter 62 so that the dq-axis currents approach the command values.

[0037] "Offset correction amount calculation process M20" Fig. 3 shows the detailed procedure of the offset correction amount calculation process M20. The process shown in Fig. 3 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval. Note that, below, the step number of each process is represented by a number preceded by "S."

[0038] In the series of processes shown in Fig. 3, the PU 72 first acquires the vehicle speed V, the steering equivalent angle θp, and the target steering equivalent angle θp*0 (S10). Next, the PU 72 determines whether or not the flag F is "1" (S12). The value of the flag F is set to "1" when the absolute value of the offset correction amount Δθp is set to a value greater than zero. The value of the flag F is set to "0" when the absolute value of the offset correction amount Δθp is zero.

[0039] When PU 72 determines that flag F is "0" (S12: NO), it determines whether a predetermined condition is met under which the absolute value of offset correction amount Δθp is set to a value greater than zero (S14). The predetermined condition is a condition under which the deviation between target turning equivalent angle θp* and turning equivalent angle θp becomes large. The predetermined condition may be the following first condition or second condition. The first condition is a condition under which target turning equivalent angle θp*0 is discontinuously changed.

[0040] Specifically, the first condition may be, for example, a condition that an abnormality has occurred in vehicle speed sensor 92. In other words, if vehicle speed sensor 92 is configured by sensors that detect the speeds of each of a plurality of wheels, the method of calculating vehicle speed V may be changed if an abnormality occurs in any one of the wheel speed sensors. In such a case, the target steering equivalent angle θp*0 changes discontinuously due to discontinuous changes in vehicle speed V. Also, for example, the first condition may be a condition that steering intervention by steering control device 70 is started. When steering intervention is started, target steering equivalent angle θp*0 changes discontinuously because the target steering equivalent angle θp*0 is set independently of steering angle θh and vehicle speed V.

[0041] The second condition is a condition that the target equivalent turning angle θp*0 and the equivalent turning angle θp deviate by a predetermined amount or more, even though the steered wheels 44 can be steered. The second condition may be, for example, a condition that the vehicle's start switch is switched from an off state to an on state. When the steering wheel 12 is rotated with the start switch in the off state, the steering angle θh and the equivalent turning angle θp become mismatched. Therefore, even though the steered wheels 44 can be steered and controlled at the time of the start switch switching, the target equivalent turning angle θp*0 deviates significantly from the equivalent turning angle θp. Alternatively, for example, the second condition may be a condition that the current limitation of the steering motor 60 is released. Specifically, for example, if the steered wheels 44 hit an obstacle such as a curb while the current of the steering motor 60 is limited, it becomes difficult to steer the steered wheels 44 toward the obstacle. In this state, if steering wheel 12 is steered toward the side that hits the obstacle, target equivalent steering angle θp*0 changes as steering angle θh changes. In contrast, equivalent steering angle θp is maintained at a constant value. If the current limitation on steering motor 60 is released in this state, there will be a large deviation between target equivalent steering angle θp*0 and equivalent steering angle θp, even though steered wheels 44 can be controlled to be steered.

[0042] When the PU 72 determines that a predetermined condition is met (S14: YES), it assigns "1" to flag F (S16). Then, the PU 72 calculates an offset amount Δθp0 which is an amount equivalent to the difference between the actual steering equivalent angle θp and the target steering equivalent angle θp* (S18). In detail, when the first condition is met, the PU 72 assigns a value obtained by subtracting the previous value "θp*0(n-1)" of the target steering equivalent angle θp*0 from the current value "θp*0(n)" of the target steering equivalent angle θp*0 to the offset amount Δθp0. Note that the steering equivalent angle θp immediately before the first condition is met is considered to be approximately equal to the target steering equivalent angle θp*0. Therefore, when the first condition is met, the "value obtained by subtracting the previous value from the current value of the target steering equivalent angle θp*0" can be considered to be the difference between the target steering equivalent angle θp* and the actual steering equivalent angle θp. In other words, when the first condition is met, "the value obtained by subtracting the previous value from the current value of the target steering equivalent angle θp*0" can be regarded as the amount equivalent to the difference between the target steering equivalent angle θp* and the actual steering equivalent angle θp. On the other hand, when the second condition is met, the PU 72 assigns the value obtained by subtracting the steering equivalent angle θp from the target steering equivalent angle θp*0 to the offset amount Δθp0.

[0043] Next, the PU 72 substitutes the offset amount Δθp0 into the offset correction amount Δθp (S20). On the other hand, when the PU 72 determines that the flag F is "1" (S12: YES), it determines whether or not the offset correction amount Δθp is zero (S22). When the PU 72 determines that the offset correction amount Δθp is greater than zero (S22: NO), it calculates the target steering equivalent angular velocity ωp*0 (S24). The target steering equivalent angular velocity ωp*0 is the rate of change of the target steering equivalent angle θp*0. The target steering equivalent angular velocity ωp*0 is calculated by the PU 72 based on the target steering equivalent angle θp*0 as an input variable.

[0044] The PU 72 determines whether the sign of the target steering-equivalent angular velocity ωp*0 is the same as the sign of the offset amount Δθp0 (S26). The target steering-equivalent angular velocity ωp*0 is a variable whose sign indicates the steering direction. If the PU 72 determines that the signs are the same (S26: YES), it performs map calculations of the steering angular velocity-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv using map data with the same sign (S28).

[0045] Figure 4 shows the same-sign map data. The same-sign map data consists of same-sign base map data 100a, same-sign gain map data 102a, and same-sign vehicle speed map data 104a. The same-sign base map data 100a is data in which the target steering equivalent angular velocity ωp*0 is an input variable and the steering angular velocity sensitive base value Δωb is an output variable. The same-sign gain map data 102a is data in which the vehicle speed V is an input variable and the vehicle speed gain Gv is an output variable. The same-sign vehicle speed map data 104a is data in which the vehicle speed V is an input variable and the vehicle speed sensitive decrease amount Δv is an output variable.

[0046] The PU 72 performs map calculation of a steering angular velocity sensitive base value Δωb using same-sign base map data 100a based on the target steering equivalent angular velocity ωp*0 as an input variable. As a result, the PU 72 changes the steering angular velocity sensitive base value Δωb according to the target steering equivalent angular velocity ωp*0 under the following condition: the absolute value of the steering angular velocity sensitive base value Δωb when the absolute value of the target steering equivalent angular velocity ωp*0 is large is equal to or greater than the absolute value of the steering angular velocity sensitive base value Δωb when the absolute value of the target steering equivalent angular velocity ωp*0 is small. The PU 72 performs map calculation of a vehicle speed gain Gv using same-sign gain map data 102a based on the vehicle speed V as an input variable. The PU 72 substitutes the product of the steering angular velocity sensitive base value Δωb and the vehicle speed gain Gv for the steering angular velocity sensitive decrease amount Δω. The PU 72 calculates the vehicle speed sensitive decrease amount Δv from a map based on the vehicle speed V as an input variable and using the same sign vehicle speed map data 104a.

[0047] On the other hand, when it is determined that the signs are opposite (S26: NO), the PU 72 performs map calculations of the steering angular velocity sensitive decrease amount Δω and the vehicle speed sensitive decrease amount Δv using the opposite sign map data (S30).

[0048] Fig. 4 shows the reverse sign map data. The reverse sign map data consists of reverse sign base map data 100b, reverse sign gain map data 102b, and reverse sign vehicle speed map data 104b. The reverse sign base map data 100b is data in which the target steering equivalent angular velocity ωp*0 is an input variable and the steering angular velocity sensitive base value Δωb is an output variable. The reverse sign gain map data 102b is data in which the vehicle speed V is an input variable and the vehicle speed gain Gv is an output variable. The reverse sign vehicle speed map data 104b is data in which the vehicle speed V is an input variable and the vehicle speed sensitive decrease amount Δv is an output variable.

[0049] The PU 72 performs map calculation of the steering angular velocity sensitive base value Δωb using the reverse sign base map data 100b based on the target steering equivalent angular velocity ωp*0 as an input variable. As a result, the PU 72 changes the steering angular velocity sensitive base value Δωb according to the target steering equivalent angular velocity ωp*0 under the following condition: the absolute value of the steering angular velocity sensitive base value Δωb when the absolute value of the target steering equivalent angular velocity ωp*0 is large is equal to or greater than the absolute value of the steering angular velocity sensitive base value Δωb when the absolute value of the target steering equivalent angular velocity ωp*0 is small. The PU 72 performs map calculation of the vehicle speed gain Gv using the reverse sign gain map data 102b based on the vehicle speed V as an input variable. The PU 72 substitutes the product of the steering angular velocity sensitive base value Δωb and the vehicle speed gain Gv for the steering angular velocity sensitive decrease amount Δω. The PU 72 calculates the vehicle speed sensitive decrease amount Δv using the reverse sign vehicle speed map data 104b based on the vehicle speed V as an input variable.

[0050] Note that map data is a set of data consisting of discrete values ​​of input variables and values ​​of output variables corresponding to each of the input variable values. Furthermore, map calculation may be a process in which, when the value of an input variable matches one of the input variable values ​​in the map data, the value of the corresponding output variable in the map data is the calculation result. Furthermore, map calculation may be a process in which, when the value of an input variable does not match any of the input variable values ​​in the map data, the calculation result is a value obtained by interpolating the values ​​of multiple output variables included in the map data. Alternatively, map calculation may be a process in which, when the value of an input variable does not match any of the input variable values ​​in the map data, the calculation result is the value of the output variable in the map data that corresponds to the closest value of the multiple input variables included in the map data.

[0051] When the processing of S28 and S30 is completed, the PU 72 substitutes the smaller of the steering angular velocity sensitive decrease amount Δω and the vehicle speed sensitive decrease amount Δv into the decrease amount Δ (S32). The PU 72 determines whether the offset amount Δθp0 is positive (S34). If the PU 72 determines that the offset amount Δθp0 is positive (S34: YES), it assigns the smaller of either zero or a value obtained by subtracting the decrease amount Δ from the offset correction amount Δθp to the offset correction amount Δθp (S36). On the other hand, if the PU 72 determines that the offset amount Δθp0 is not positive (S34: NO), it assigns the larger of either zero or a value obtained by adding the decrease amount Δ to the offset correction amount Δθp to the offset correction amount Δθp (S38).

[0052] As is clear from the processes of S36 and S38, the decrease amount Δ is a decrease variable that defines the decrease rate of the magnitude of the offset correction amount Δθp. Incidentally, the decrease rate of the magnitude of the offset correction amount Δθp is expressed as "Δ / Tc" using the cycle Tc of the series of processes shown in FIG.

[0053] On the other hand, if the PU 72 determines that the offset correction amount Δθp is zero (S22: YES), it assigns "0" to flag F (S42). If the determination in the process of S14 is negative, the PU 72 assigns zero to the offset correction amount Δθp (S40).

[0054] When the PU 72 completes the processes of S20 and S36 to S42, it temporarily ends the series of processes shown in FIG. "Actions and Effects of the Present Embodiment" Fig. 5 illustrates a process for gradually decreasing the magnitude of the offset correction amount Δθp when a predetermined condition is met. In Fig. 5, a two-dot chain line indicates the relationship between the target steering equivalent angle θp*0 and the steering angle θh before the predetermined condition is met. In Fig. 5, a one-dot chain line indicates the relationship between the target steering equivalent angle θp*0 and the steering angle θh after the predetermined condition is met. In Fig. 5, a steering-back curve fb indicates the transition of the target steering equivalent angle θp* in the case of steering back. In Fig. 5, a steering-on curve ft indicates the transition of the target steering equivalent angle θp* in the case of steering.

[0055] Figure 5(a) shows a case where the target steering angle ratio is smaller and the offset amount Δθp0 is negative after the predetermined condition is met. In this case, at time t1 when the predetermined condition is met, the offset amount Δθp0 is subtracted from the target steering equivalent angle θp*0 shown by the dashed line in Figure 5(a). Therefore, the absolute value of the target steering equivalent angle θp* is larger than the absolute value of the target steering equivalent angle θp*0 shown by the dashed line.

[0056] 5(a), the sign of the target steering equivalent angular velocity ωp*0 in the case of steering back is the same as the sign of the offset amount Δθp0. Therefore, as the magnitude of the offset correction amount Δθp gradually decreases at a reduction rate defined by the reduction amount Δ, the magnitude of the rate of change of the target steering equivalent angle θp* becomes larger than the magnitude of the target steering equivalent angular velocity ωp*0.

[0057] 5(a), the sign of the target steering equivalent angular velocity ωp*0 in the case of turning is opposite to the sign of the offset amount Δθp0. Therefore, as the magnitude of the offset correction amount Δθp gradually decreases at a reduction rate defined by the reduction amount Δ, the magnitude of the rate of change of the target steering equivalent angle θp* becomes smaller than the magnitude of the target steering equivalent angular velocity ωp*0.

[0058] That is, in the example shown in Figure 5(a), the gradual decrease process of the magnitude of the offset correction amount Δθp amplifies the change in the target steering equivalent angle θp* when steering back, while suppressing the change in the target steering equivalent angle θp* when steering forward.

[0059] 5(b) shows a case where the target steering angle ratio is larger and the offset amount Δθp0 is positive after the predetermined condition is met. In this case, at time t2 when the offset amount Δθp0 is subtracted from the target steering equivalent angle θp*0 indicated by the dashed dotted line, the absolute value of the target steering equivalent angle θp* is smaller than the absolute value of the target steering equivalent angle θp*0 indicated by the dashed dotted line.

[0060] 5(b), the sign of the target steering equivalent angular velocity ωp*0 in the case of steering back is opposite to the sign of the offset amount Δθp0. Therefore, as the magnitude of the offset correction amount Δθp gradually decreases at a reduction rate defined by the reduction amount Δ, the magnitude of the rate of change of the target steering equivalent angle θp* becomes smaller than the magnitude of the target steering equivalent angular velocity ωp*0.

[0061] 5(b), the sign of the target steering equivalent angular velocity ωp*0 in the case of turning is the same as the sign of the offset amount Δθp0. Therefore, as the magnitude of the offset correction amount Δθp gradually decreases at a reduction rate defined by the reduction amount Δ, the magnitude of the rate of change of the target steering equivalent angle θp* becomes larger than the magnitude of the target steering equivalent angular velocity ωp*0.

[0062] That is, in the example shown in Figure 5(b), the gradual decrease process of the magnitude of the offset correction amount Δθp suppresses the change in the target steering equivalent angle θp* when steering back, while amplifying the change in the target steering equivalent angle θp* when steering forward.

[0063] From the above, if the decrease amount Δ were set to the same value whether the sign of the target steering equivalent angular velocity ωp*0 and the sign of the offset amount Δθp0 matched or not, the effect that the gradual decrease process has on the rate of change of the target steering equivalent angle θp* would differ depending on whether they matched. Therefore, if the decrease amount Δ were adjusted to an appropriate value when the two signs matched, there is a risk that the absolute value of the rate of change of the target steering equivalent angle θp* would become excessively small if the two signs were opposite. On the other hand, if the decrease amount Δ were adjusted to an appropriate value when the two signs mismatched, there is a risk that the absolute value of the rate of change of the target steering equivalent angle θp* would become excessively large if the two signs were the same.

[0064] Therefore, in this embodiment, the PU 72 sets the decrease amount Δ to a larger value when it is determined that the two signs do not match than when it is determined that the two signs match, thereby making it possible to set the rate of change of the target steering equivalent angle θp* to an appropriate value regardless of whether the two signs match or not.

[0065] According to the present embodiment described above, the following actions and effects can be further obtained. (1-1) PU 72 changed the steering angular velocity sensitive base value Δωb in accordance with the target steering equivalent angular velocity ωp*0 under the following condition. The condition is that the absolute value of the steering angular velocity sensitive base value Δωb when the magnitude of the target steering equivalent angular velocity ωp*0 is large is equal to or greater than the steering angular velocity sensitive base value Δωb when the magnitude of the target steering equivalent angular velocity ωp*0 is small. When the magnitude of the target steering equivalent angular velocity ωp*0 is large, there is a high possibility that a steering request has been made to change the steering angle early. Therefore, according to the above condition, when there is a high possibility that a steering request has been made to change the steering angle early, it is possible to quickly bring the target steering equivalent angle θp* close to the target steering equivalent angle θp*0.

[0066] However, in that case, if the rate of decrease in the magnitude of the offset correction amount Δθp is determined regardless of the above two signs, for example, when a steering request to change the steering angle early occurs, inconveniences such as a delay in changing the steering angle occur. In other words, when the above two signs do not match, the gradual decrease in the magnitude of the offset correction amount acts to cancel out the change in the target steering equivalent angle θp*0, so increasing the rate of decrease ends up suppressing the change in the target steering equivalent angle θp*.

[0067] Therefore, the process of changing the decrease amount Δ depending on whether the two signs match or mismatch is particularly useful. (1-2) The same-sign base map data 100a and the opposite-sign base map data 100b are provided, so that the steering angular velocity sensitive base value Δωb can be set to an appropriate value when the two signs match or do not match.

[0068] (1-3) The same sign gain map data 102a and the opposite sign gain map data 102b are provided, so that the vehicle speed gain Gv can be set to an appropriate value when the two signs match or do not match.

[0069] (1-4) Same-sign vehicle speed map data 104a and opposite-sign vehicle speed map data 104b are provided, so that the vehicle speed-sensitive decrease amount Δv can be set to an appropriate value when the two signs match or do not match.

[0070] <Second embodiment> The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0071] Fig. 6 shows a detailed procedure of the offset correction amount calculation process M20. The process shown in Fig. 6 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval. For convenience, the same step numbers are used in Fig. 6 to designate processes corresponding to those shown in Fig. 3.

[0072] In the series of processes shown in FIG. 6, when the PU 72 completes the process of S24, it performs map calculations of the steering angular velocity-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv (S50). The map data used here is data adapted assuming that the sign of the target steering equivalent angular velocity ωp*0 and the sign of the offset amount Δθp0 match. The map data used here may be same-sign base map data 100a, same-sign gain map data 102a, and same-sign vehicle speed map data 104a. Next, the PU 72 determines whether the sign of the target steering equivalent angular velocity ωp*0 and the sign of the offset amount Δθp0 match (S26). If the PU 72 determines that the two signs do not match (S26: NO), it increases the steering angular velocity-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv (S52). Specifically, the PU 72 multiplies the steering angular speed-sensitive decrease amount Δω calculated by the processing of S50 by the high-speed gain Gtω and assigns the result to the steering angular speed-sensitive decrease amount Δω. The PU 72 multiplies the vehicle speed-sensitive decrease amount Δv calculated by the processing of S50 by the high-speed gain Gtv and assigns the result to the vehicle speed-sensitive decrease amount Δv. Both the high-speed gain Gtω and the high-speed gain Gtv are set to values ​​greater than "1."

[0073] If the PU 72 makes a positive determination in the process of S26 or completes the process of S52, the PU 72 proceeds to the process of S32. "Actions and Effects of the Present Embodiment" When the sign of the target steering-equivalent angular velocity ωp*0 and the sign of the offset amount Δθp0 are opposite, the PU 72 increases the steering angular velocity-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv calculated by the processing of S50. This reduces the number of map data.

[0074] <Third embodiment> The third embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment.

[0075] Fig. 7 shows the detailed procedure of the offset correction amount calculation process M20. The process shown in Fig. 7 is realized by the PU 72 repeatedly executing a program stored in the storage device 74, for example, at a predetermined interval. For convenience, the same step numbers are used in Fig. 7 to refer to processes corresponding to those shown in Fig. 3.

[0076] In the series of processes shown in FIG. 7, if the determination in S26 is affirmative, the PU 72 determines whether the steering wheel is being turned (S60). The input variables in S60 may be, for example, at least one of the following four variables: steering torque Th, rate of change of steering angle θh, rate of change of steering equivalent angle θp, and target steering equivalent angular velocity ωp*0. The input variables may also include at least one of the following three variables: steering angle θh, steering equivalent angle θp, and target steering equivalent angle θp*. If the PU 72 determines that the steering wheel is being turned (S60: YES), it performs map calculations of the steering angular velocity-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv using same-sign map data for turning (S62). The same-sign map data for turning is data obtained by adapting the same-sign base map data 100a, same-sign gain map data 102a, and same-sign vehicle speed map data 104a described above so as to be particularly suitable for turning the wheel. On the other hand, when it is determined that the steering is returning (S60: NO), the PU 72 performs map calculations of the steering angular velocity-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv using the same-sign map data for returning (S64). The same-sign map data for returning is data that is obtained by adapting the same-sign base map data 100a, same-sign gain map data 102a, and same-sign vehicle speed map data 104a described above so as to be particularly suitable for returning.

[0077] If the determination in S26 is negative, the PU 72 determines whether the steering wheel is being turned (S66). If the PU 72 determines that the steering wheel is being turned (S66: YES), the PU 72 performs map calculations of the steering angular speed-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv using the reverse sign map data for turning (S68). The reverse sign map data for turning is data that has been adapted to the above-mentioned reverse sign base map data 100b, reverse sign gain map data 102b, and reverse sign vehicle speed map data 104b so as to be particularly appropriate for turning the wheel. On the other hand, if the PU 72 determines that the steering wheel is being returned (S66: NO), the PU 72 performs map calculations of the steering angular speed-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv using the reverse sign map data for returning (S70). The reverse sign map data for steering back is data obtained by adapting the above-mentioned reverse sign base map data 100b, reverse sign gain map data 102b, and reverse sign vehicle speed map data 104b so as to be particularly suitable for steering back.

[0078] When the PU 72 completes the processes of S62, S64, S68, and S70, it proceeds to the process of S32. "Actions and Effects of the Present Embodiment" Even if the two signs are the same, the PU 72 sets the decrease amount Δ for steering in and steering back separately, which allows for more precise setting of the steering feel compared to when the speed at which the offset correction amount Δθp is decreased is set to the same for steering in and steering back.

[0079] <Correspondence> The correspondence between the matters in the above embodiment and the matters described in the "Means for Solving the Problem" column is as follows. Below, the correspondence is shown for each number of the solving means described in the "Means for Solving the Problem" column. The operation processing corresponds to the steering feedback processing M24 and the steering operation processing M26. The offset amount calculation processing corresponds to the processing of S18. The offset compensation processing corresponds to the offset correction processing M22, etc. The offset reduction processing corresponds to the processing of S34 to S38. The determination processing corresponds to the processing of S26. The steering direction is quantified by the sign of the target steering equivalent angular velocity ωp*0. [2] The steering angular velocity variable corresponds to the target steering equivalent angular velocity ωp*0. The angular velocity sensitive processing corresponds to the processing of calculating the steering angular velocity sensitive decrease amount Δω using same-sign base map data 100a and opposite-sign base map data 100b. [3] The angular velocity sensitive regulation data corresponds to same-sign base map data 100a and opposite-sign base map data 100b. [4] Corresponds to the processing in Figure 6. In particular, the gains correspond to the high-speed gains Gtω and Gtv. [5] The vehicle speed sensing regulation data corresponds to the same-sign vehicle speed map data 104a and the opposite-sign vehicle speed map data 104b. [6] The identification processing corresponds to the processing in S60 and S66.

[0080] <Other embodiments> This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0081] "About steering direction" The steering angular velocity variable to be judged for agreement or disagreement with the sign of the offset correction amount Δθp is not limited to the target steering equivalent angular velocity ωp*0. For example, it may be the rate of change of the steering angle θh.

[0082] The variable indicating the steering direction, which is the variable to be checked for agreement or disagreement with the sign of the offset correction amount Δθp, is not limited to the steering angular velocity variable. For example, it may be the steering torque Th.

[0083] "About the judgment process" The input variable for the process of determining whether the sign of the steering angular velocity variable value matches the sign of the offset correction amount does not necessarily have to be the offset amount Δθp0. For example, the input variable may be the offset correction amount Δθp itself.

[0084] The determination process does not necessarily have to be a process for determining whether the product of the steering angular velocity variable value and the offset amount Δθp0 is positive or negative. For example, the determination process may include a first determination process, a second determination process, and a third determination process. Here, the first determination process is a process for determining whether the value of the steering angular velocity variable is positive or negative. The second determination process is a process for determining whether the sign of the offset amount Δθp0 is positive or negative. The third determination process is a process for determining whether the following logical sum is true or negative. The logical sum is a logical sum of a positive determination made by the first determination process and a positive determination made by the second determination process, and a negative determination made by the first determination process and a negative determination made by the second determination process.

[0085] "About angular velocity sensitive processing" The angular velocity sensitive processing is not limited to processing that calculates the steering angular velocity sensitive decrease amount Δω using a map based on the target steering equivalent angular velocity ωp*0 as an input variable. The angular velocity sensitive processing may, for example, be processing that calculates the steering angular velocity sensitive decrease amount Δω using a map based on the rate of change of the steering angle θh as an input variable. Even in this case, the angular velocity sensitive processing is processing that calculates the steering angular velocity sensitive decrease amount Δω using a map in accordance with the rate of change of the target steering equivalent angle. This is because the rate of change of the target steering equivalent angle has a positive correlation with the rate of change of the steering angle θh.

[0086] The angular velocity sensitive processing is not limited to processing that calculates the steering angular velocity sensitive decrease amount Δω based on the target steering equivalent angular velocity ωp*0 and the vehicle speed V as input variables. For example, the angular velocity sensitive processing may be processing that calculates the steering angular velocity sensitive decrease amount Δω based only on the target steering equivalent angular velocity ωp*0 as an input variable. In other words, the vehicle speed gain Gv is not essential.

[0087] The angular velocity sensitive process does not necessarily have to be a process of calculating the steering angular velocity sensitive decrease amount Δω using map data. The angular velocity sensitive process may be a process of calculating the steering angular velocity sensitive decrease amount Δω using a predetermined formula, for example.

[0088] "About Vehicle Speed ​​Sensing Processing" The vehicle speed-sensitive processing does not necessarily have to be a process of calculating the vehicle speed-sensitive decrease amount Δv using map data. The vehicle speed-sensitive processing may be a process of calculating the vehicle speed-sensitive decrease amount Δv using a predetermined formula, for example.

[0089] "About offset reduction processing" The offset reduction process does not necessarily have to be a process of substituting the smaller of the vehicle speed-sensitive decrease amount Δv and the steering angular velocity-sensitive decrease amount Δω for the decrease amount Δ. The offset reduction process may be a process of calculating the decrease amount Δ from a map using map data in which a steering angular velocity variable such as a target steering equivalent angular velocity ωp*0 and the vehicle speed V are input variables and the decrease amount Δ is an output variable. Also, for example, the offset reduction process may be a process of calculating the decrease amount Δ from a map using map data in which the vehicle speed V is an input variable and the decrease amount Δ is an output variable.

[0090] The decrease amount Δ may be the sum of the steering angular velocity sensitive decrease amount Δω and the vehicle speed sensitive decrease amount Δv. 6, the steering angular velocity-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv are corrected by multiplying them by a gain when the determination in S26 is negative, but this is not limiting. For example, the PU 72 may correct the steering angular velocity-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv by multiplying them by a gain when the determination in S26 is positive. Also, for example, instead of correcting the steering angular velocity-sensitive decrease amount Δω and the vehicle speed-sensitive decrease amount Δv, the PU 72 may correct the decrease amount Δ itself by a single gain when the determination in S26 is positive.

[0091] The calculation process of the decrease amount Δ using the discrimination process for distinguishing between steering back and steering back is not limited to the process exemplified in Fig. 7. The calculation process of the decrease amount Δ using the discrimination process may be, for example, a process of correcting the decrease amount Δ calculated by the process exemplified in Fig. 6 by multiplying it by a gain in the case of either steering back or steering back. Also, for example, the calculation process of the decrease amount Δ using the discrimination process may be a process of map-calculating the decrease amount Δ using the following map data. The map data is data in which a binary variable indicating the discrimination result of the discrimination process, the target steering equivalent angular velocity ωp*0, and the vehicle speed are input variables, and the decrease amount Δ is an output variable.

[0092] "Regarding steering requests" In the above embodiment, the target steering equivalent angle θp*0 is set according to the steering angle θh, which is the rotation angle of the steering wheel 12, which serves as an operation unit through which the driver inputs a steering request. However, this is not limited to this. For example, the target steering equivalent angle θp*0 may be set by automated driving. In this case, the steering request is quantified by the value of a variable calculated when the automated driving drives the vehicle to satisfy a predetermined request. This variable may be the target steering equivalent angle θp*0 itself.

[0093] "About steering control devices" The steering control device is not limited to one that executes various processes using a PU. For example, it may be equipped with a dedicated hardware circuit, such as an ASIC, that executes at least part of the processes executed in the above embodiments. That is, the steering control device may be equipped with any of the following processing circuits (a) to (c): (a) A processing circuit that includes a processing device that executes all of the above processes in accordance with a program, and a program storage device such as a memory device that stores the program. (b) A processing circuit that includes a processing device and program storage device that executes part of the above processes in accordance with a program, and a dedicated hardware circuit that executes the remaining processes. (c) A processing circuit that includes a dedicated hardware circuit that executes all of the above processes. Here, there may be multiple software execution devices that include a processing device and a program storage device, and multiple dedicated hardware circuits.

[0094] "About steering actuators" The steering actuator At may be, for example, one in which steering motor 60 is arranged coaxially with steering shaft 40. Alternatively, for example, one in which steering motor 60 is connected to steering shaft 40 via a belt-type reducer using a ball screw mechanism may be used. [Explanation of symbols]

[0095] 10...Steering device 12...Steering wheel 14...Steering shaft 16...Reduction mechanism 20...Reaction motor 22...Reaction force inverter 40...Steering shaft 42...Tie rod 44...Steering wheel 50...Rack and pinion mechanism 52...Pinion shaft 54...Rack teeth 56…Reduction mechanism 60...Steering motor 62...Steering inverter 70...Steering control device

Claims

1. The system is configured to execute a target steering equivalent angle setting process, an operation process, an offset amount calculation process, an offset compensation process, a determination process, and an offset reduction process in a state where the steered wheels and the steering shaft are mechanically disconnected, the target steering equivalent angle setting process is a process for setting a target steering equivalent angle in response to a steering request, the target steering equivalent angle is a target value of a steering equivalent angle which is a variable indicating the steering angle of the steered wheels, the operation processing is processing for operating a motor that steers the steered wheels in accordance with an operation amount of control in which the target steering equivalent angle is a target value of a control amount, the offset amount calculation process is a process of calculating an offset amount that is an amount equivalent to a difference between the actual steering equivalent angle and the target steering equivalent angle, when a predetermined condition is satisfied as a trigger, the offset compensation process is a process of subtracting and correcting the target steering equivalent angle as an input variable of the operation process by an offset correction amount corresponding to the offset amount, the determination process is a process for determining whether or not a sign of the steering direction and a sign of the offset correction amount match, The offset reduction process is a process for reducing the magnitude of the offset correction amount, and includes a process for setting a reduction rate of the magnitude of the offset correction amount to a larger value when the determination process determines that the offset correction amount does not match than when the determination process determines that the offset correction amount matches.

2. the offset reduction process includes angular velocity sensitive processing, 2. A steering control device according to claim 1, wherein the angular velocity sensitive processing is a processing for changing the rate of decrease in accordance with the rate of change of the target steering equivalent angle, on the condition that the rate of decrease when the magnitude of the rate of change of the target steering equivalent angle is large is equal to or greater than the rate of decrease when the magnitude of the rate of change of the target steering equivalent angle is small.

3. a storage device for storing angular velocity sensitive regulation data; the angular velocity sensitive processing is performed using the angular velocity sensitive definition data; the angular velocity response regulation data is map data in which a steering angular velocity variable is an input variable and a reduction variable is an output variable, and the map data is composed of separate data corresponding to whether or not the determination result of the determination process indicates a match; the steering angle speed variable is a variable indicating a rate of change of the target steering equivalent angle, 3. The steering control device according to claim 2, wherein the decrease variable is a variable indicating the decrease speed.

4. 3. A steering control device according to claim 2, wherein the offset reduction process reduces the magnitude of the offset correction amount in accordance with a reduction rate set by angular velocity sensitive processing when the judgment result of the judgment process is either a match or a mismatch, and reduces the magnitude of the offset correction amount in accordance with a value obtained by multiplying a gain by the reduction rate set by angular velocity sensitive processing when the judgment result of the judgment process is the other of the two.

5. a storage device that stores vehicle speed sensitive regulation data; The offset reduction process includes a vehicle speed sensitive process, the vehicle speed sensitive processing is a processing that is defined by the vehicle speed sensitive definition data and that changes the decrease rate in accordance with the vehicle speed as an input variable, 2. A steering control device according to claim 1, wherein said vehicle speed sensitive regulation data comprises separate data corresponding to match and mismatch in said determination process.

6. configured to perform an identification process; the identification process is a process for identifying a cut and a cutback, 2. The steering control device according to claim 1, wherein the offset reduction process includes a process for changing a reduction rate of the magnitude of the offset correction amount between the turning and the returning even when the determination result of the determination process is a match.

Images