JP2023135038A - Steering control device - Google Patents

Abstract

To provide a steering control device that can suppress a sudden change in the value of an angle variable handled by a control device due to a change in a mode variable.SOLUTION: A PU 72 outputs a sum of a twist amount calculated from a steering torque Th and a rotation angle of a steering wheel 12 to a steering ECU 90 as a control steering angle. The steering ECU 90 calculates a target steering angle by correcting the control steering angle according to a vehicle speed V. The PU 72 calculates the twist amount to a different value depending on a mode instructed by operation of a user interface 86. When the mode is switched, the PU 72 gradually changes the twist amount.SELECTED DRAWING: Figure 1

Description

The present invention relates to a steering control device.

For example, Patent Document 1 listed below describes a device in which a steering wheel and steered wheels of a vehicle are mechanically separated. Further, this document describes that a target turning angle is set according to a steering angle that is a rotation angle of a steering wheel.

Further, Patent Document 2 listed below describes a vehicle equipped with a device that generates assist torque using a motor when steering wheels are steered by operating a steering wheel. This document describes a device that changes the steering feel by changing the torque that assists steering wheel operation in two driving modes, a sports mode and a normal mode.

JP2021-30838A International Publication No. 2011/48772

The inventor considered providing a sport mode and a normal mode in a device in which a steering wheel and steered wheels of a vehicle are mechanically separated. In that case, there is a risk that the value of the angle variable handled by the control device may suddenly change when switching modes.

Below, means for solving the above problems and their effects will be described.
1. Applied to a vehicle equipped with a steering system capable of changing the relationship between a steering angle and a turning angle, the steering angle is a rotation angle of a steering wheel, and the turning angle is a turning angle of a turning wheel of the vehicle. Yes, the angular variable calculation process is a process of calculating the value of the angular variable according to the value of the mode variable, and the angular variable calculation process is a process of calculating the value of the angular variable according to the value of the mode variable. is a variable indicating the driver's preference for the operating feel of the vehicle, the angle variable is a variable indicating the steering angle, and the operation processing is a variable that indicates the steering system using the value of the angle variable as input. When the value of the mode variable is changed, the gradual change process changes the value of the angle variable, which is input to the operation process, to the angle corresponding to the value of the mode variable before the change. The steering control device is a process for gradually shifting the value of the variable to the value of the angle variable corresponding to the changed value of the mode variable.

In the above configuration, the value of the angle variable is calculated according to the value of the mode variable. Since the mode variable is a variable that indicates the driver's preference regarding the operating feel of the vehicle, the value of the angle variable is calculated to a value that corresponds to the driver's preference according to the mode variable. Here, when the value of the mode variable is changed, the value of the angle variable may change rapidly, causing an unintended operation of the steering system. Therefore, in the above configuration, the value of the angle variable is gradually changed by the gradual change process. Thereby, it is possible to suppress sudden changes in the values of the angle variables handled by the control device.

2. The steering control device according to 1 above, wherein the angle variable is a target steering angle variable that is a variable indicating a target value of the steering angle.
In the above configuration, the value of the target turning angle variable is calculated according to the value of the mode variable. Therefore, when the value of the mode variable is changed, the value of the target turning angle variable may change suddenly. If the value of the target turning angle variable changes suddenly, there is a risk that the actual turning angle will change suddenly. On the other hand, in the above configuration, by gradually changing the value of the target turning angle variable through the gradual change process, it is possible to suppress a sudden change in the actual turning angle.

3. The angle variable calculation process is a process of calculating the value of the target turning angle variable by shifting the value of the target turning angle variable by a predetermined amount with respect to the basic turning angle indicated by the steering angle. and the process of variably setting the predetermined amount according to the value of the mode variable, and the gradual change process changes the predetermined amount from the predetermined amount according to the value of the mode variable before the change to the mode after the change. By gradually shifting to the predetermined amount according to the value of the variable, the value of the target steering angle variable according to the value of the mode variable before the change changes to the value of the mode variable after the change. The steering control device according to the above 2, wherein the steering control device is a process of gradually shifting the target steering angle variable to the value of the target steering angle variable.

In the above configuration, by determining the predetermined amount according to the value of the mode variable, the driver's preference can be reflected in the value of the target turning angle variable.
4. The angle variable calculation process includes a torsion angle calculation process and a gain multiplication process, and the torsion angle calculation process is a process of calculating a torsion angle according to a detected value of torque input to the steering wheel, The gain multiplication process is a process of calculating the predetermined amount by multiplying the torsion angle by a gain, and is a process of variably setting the gain according to the value of the mode variable, and the gradual change process is a process of calculating the predetermined amount by multiplying the torsion angle by a gain. , by gradually shifting from the gain depending on the value of the mode variable before the change to the gain depending on the value of the mode variable after the change, depending on the value of the mode variable before the change. 4. The steering control device according to the above 3, wherein the steering control device gradually shifts from the predetermined amount to the predetermined amount corresponding to the changed value of the mode variable.

In the above configuration, the predetermined amount is determined according to the amount by which the torsion angle is multiplied by the gain. Here, the gain is set according to the value of the mode variable. Therefore, by subjecting the change in gain to gradual variation processing, changes in the mode variable can be directly addressed compared to cases where the predetermined amount or the value of the target turning angle variable itself is subject to gradual variation processing. can do.

5. The gain multiplication process is a process of variably setting the gain according to the vehicle speed, and includes a process of setting the gain to a different size depending on the value of the mode variable even if the vehicle speed is the same. This is the steering control device according to 4 above.

In the above configuration, since the gain is set according to the mode variable and the vehicle speed, the value of the target turning angle variable can be set to a more appropriate value according to the vehicle speed.

FIG. 1 is a diagram showing the configuration of a vehicle according to a first embodiment. It is a block diagram showing a part of processing that steering ECU concerning the same embodiment performs. It is a flowchart which shows the procedure of the process which steering ECU concerning the same embodiment performs. It is a flowchart which shows the procedure of the process which the steering ECU concerning 2nd Embodiment performs.

<First embodiment>
A first embodiment of the steering control device will be described below with reference to the drawings.
"Prerequisite configuration"
As shown in FIG. 1, a vehicle steering system 10 is a steer-by-wire type steering system. The steering device 10 includes a reaction force actuator Ar and a steering actuator At. The steering device 10 of this embodiment has a structure in which a power transmission path between the steering wheel 12 and the steered wheels 44 is always mechanically blocked.

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 refers to a force that acts in a direction opposite to the direction in which the steering wheel 12 is operated by the driver. By applying a steering reaction force to the steering wheel 12, it is possible to give the driver an appropriate feeling of response. The reaction actuator Ar includes a speed reduction mechanism 16, a reaction motor 20, and a reaction inverter 22.

The reaction motor 20 is a three-phase brushless motor. A rotating shaft of the reaction motor 20 is connected to the steering shaft 14 via a speed reduction mechanism 16 .
On the other hand, the steering shaft 40 extends along the vehicle width direction, which is the left-right direction in FIG. Left and right steered wheels 44 are connected to both ends of the steered shaft 40 via tie rods 42, respectively. By linearly moving the steered shaft 40, the steered angle of the steered wheels 44 is changed.

The steering actuator At includes a speed reduction mechanism 56, a steering motor 60, and a steering inverter 62. The steering motor 60 is a three-phase brushless motor. A rotating shaft of the steering motor 60 is connected to the pinion shaft 52 via a speed reduction mechanism 56. The pinion teeth of the pinion shaft 52 are engaged with the rack teeth 54 of the steered shaft 40. The pinion shaft 52 and the steered shaft 40 on which the rack teeth 54 are formed constitute a rack and pinion mechanism 50. The torque of the steering motor 60 is applied to the steering shaft 40 via the pinion shaft 52 as a steering force. In accordance with the rotation of the steering motor 60, the steering shaft 40 moves along the vehicle width direction, which is the left-right direction in FIG.

The steering device 10 includes a reaction force ECU 70 and a steering ECU 90.
The reaction force ECU 70 controls the steering wheel 12. The reaction force ECU 70 operates the reaction force actuator Ar in order to control the steering reaction force as a controlled variable to be controlled. In FIG. 1, an operation signal MSs to the reaction force inverter 22 is shown.

The reaction force ECU 70 refers to the steering torque Th, which is the input torque to the steering shaft 14 and is detected by the torque sensor 80, in order to control the control amount. Further, the reaction force ECU 70 refers to the rotation angle θa of the rotation shaft of the reaction force motor 20 detected by the rotation angle sensor 82. The reaction force ECU 70 also refers to the vehicle speed V detected by the vehicle speed sensor 84. The reaction force ECU 70 also refers to the operating state of the user interface 86. User interface 86 allows input indicating the driver's preferred feel of operating the vehicle. In this embodiment, two modes, normal mode and sport mode, are selectable by the driver. The sport mode is a mode in which the responsiveness of the steered wheels 44 to the operation of the steering wheel 12 is higher than that in the normal mode. Further, the reaction force ECU 70 refers to the currents iu1, iv1, and iw1 flowing through the reaction force motor 20. The currents iu1, iv1, and iw1 are quantified as voltage drops across shunt resistors provided in each leg of the reaction force inverter 22.

The reaction force ECU 70 includes a PU 72, a storage device 74, and a peripheral circuit 76. The PU 72 is a software processing device such as a CPU, GPU, and TPU. Here, the peripheral circuit 76 includes a circuit that generates a clock signal that defines internal operations, a power supply circuit, a reset circuit, and the like. The reaction force ECU 70 controls the control amount when the PU 72 executes a program stored in the storage device 74.

The steering ECU 90 controls the steered wheels 44. The steering ECU 90 operates the steering actuator At in order to control the steering angle of the steered wheels 44 as a controlled variable to be controlled. FIG. 1 shows an operation signal MSt to the steering inverter 62.

The steering ECU 90 refers to the rotation angle θb of the rotation shaft of the steering motor 60 detected by the rotation angle sensor 83 in order to control the control amount. Further, the steering ECU 90 refers to the currents iu2, iv2, and iw2 flowing through the steering motor 60. The currents iu2, iv2, and iw2 are quantified as voltage drops across shunt resistors provided in each leg of the steering inverter 62.

The steering ECU 90 includes a PU 92, a storage device 94, and a peripheral circuit 96. The PU92 is a software processing device such as a CPU, GPU, and TPU. The steering ECU 90 controls the control amount when the PU 92 executes a program stored in the storage device 94.

"control"
FIG. 2 shows a part of the processing executed by the reaction force ECU 70 and the steering ECU 90.
The pinion angle calculation process M8 is a process for calculating the pinion angle θp, which is the rotation angle of the pinion shaft 52, using the rotation angle θb as an input. The pinion angle calculation process M8 includes a range exceeding 360°, for example, by counting the number of rotations of the steering motor 60 from the rack neutral position, which is the position of the steering shaft 40 when the vehicle is traveling straight. Includes processing to convert into integrated angle. The pinion angle calculation process M8 is a process of calculating the pinion angle θp, which is the actual rotation angle of the pinion shaft 52, by multiplying the converted integrated angle by a conversion coefficient based on the rotation speed ratio of the reduction mechanism 56. including. Note that the pinion angle θp is positive when the angle is to the right of the rack neutral position, and negative when the pinion angle is to the left of the rack neutral position. The steering motor 60 and the pinion shaft 52 are interlocked via a speed reduction mechanism 56. Therefore, there is a correlation between the rotation angle θb of the steering motor 60 and the pinion angle θp. Using this correlation, the pinion angle θp can be determined from the rotation angle θb of the steering motor 60. Further, the pinion shaft 52 is meshed with the steered shaft 40. Therefore, there is also a correlation between the pinion angle θp and the amount of movement of the steered shaft 40. That is, the pinion angle θp is a value that reflects the turning angle of the turning wheels 44. Note that the pinion angle calculation process M8 is a process executed in the steering ECU 90.

The steering reaction force command value calculation process M10 is a process of calculating a steering reaction force command value Tr* according to the steering reaction force to be applied to the steering wheel 12 using the steering torque Th, vehicle speed V, and pinion angle θp as input. be. The steering reaction force command value Tr* is actually a command value for the reaction force motor 20. A value obtained by multiplying the steering reaction force command value Tr* by a coefficient corresponding to the reduction ratio of the reduction gear mechanism 16 becomes the steering reaction force. The steering reaction force command value calculation process M10 is a process executed in the reaction force ECU 70.

The reaction force operation process M12 is a process of inputting the steering reaction force command value Tr*, the currents iu1, iv1, iw1, and the rotation angle θa, and outputting the operation signal MSs to the reaction force inverter 22. The reaction force operation process M12 includes a process of calculating the dq-axis current command value based on the steering reaction force command value Tr*. Further, the reaction force operation process M12 includes a process of calculating the dq-axis current based on the currents iu1, iv1, iw1 and the rotation angle θa. The reaction force operation process M12 includes a process of calculating an operation signal MSs to operate the reaction force inverter 22 so that the dq-axis current becomes a command value. The reaction force operation process M12 is a process executed in the reaction force ECU 70.

The steering angle calculation process M14 is a process of calculating the steering angle θh, which is the rotation angle of the steering wheel 12, using the rotation angle θa as an input. The steering angle calculation process M14 calculates the rotation angle θa by, for example, 360° by counting the number of rotations of the reaction force motor 20 from the steering neutral position, which is the position of the steering wheel 12 when the vehicle is traveling straight. Includes processing to convert into an integrated angle that includes the range beyond. The steering angle calculation process M14 includes a process of calculating the steering angle θh by multiplying the integrated angle obtained by the conversion by a conversion coefficient based on the rotational speed ratio of the speed reduction mechanism 16. Note that the steering angle θh is, for example, positive when the angle is to the right of the steering neutral position, and negative when the angle is to the left of the steering neutral position. The steering angle calculation process M14 is a process executed in the reaction force ECU 70.

The torsion angle calculation process M16 is a process for calculating the torsion angle Δθh of the torque sensor 80 using the steering torque Th as input. The torsion angle calculation process M16 is a process in which the PU 72 performs a map calculation of the torsion angle Δθh with the map data stored in the storage device 74. Here, the map data is data that uses the steering torque Th as an input variable and the torsion angle Δθh as an output variable. Note that map data is set data of discrete values of input variables and values of output variables corresponding to each of the values of the input variables. Furthermore, the map calculation may be a process in which when the value of the input variable matches any of the values of the input variables of the map data, the value of the output variable of the corresponding map data is used as the calculation result. Additionally, map calculation is a process in which when the value of an input variable does not match any of the values of input variables in map data, the calculation result is a value obtained by interpolating the values of multiple output variables included in map data. do it. Alternatively, if the value of the input variable does not match any of the values of the input variables in the map data, the map operation will match the closest value among the values of the multiple output variables contained in the map data. It is also possible to use the value of the output variable of the map data as the calculation result.

The torsion angle calculation process M16 is a process executed in the reaction force ECU 70.
The normal gain calculation process M18 is a process for calculating a gain in the normal mode based on the vehicle speed V. The gain is a coefficient that adjusts the magnitude of the torsion angle Δθh by being multiplied by the torsion angle Δθh. The normal gain calculation process M18 is a process in which the PU 72 performs a map calculation of the gain while the map data is stored in the storage device 74. The normal gain calculation process M18 is a process executed in the reaction force ECU 70.

The sports gain calculation process M20 is a process for calculating the gain of the sports mode based on the vehicle speed V. The gain is a coefficient that adjusts the magnitude of the torsion angle Δθh by being multiplied by the torsion angle Δθh. The sports gain calculation process M20 is a process in which the PU 72 performs a map calculation of the gain while the map data is stored in the storage device 74. The sports gain calculation process M20 is a process executed in the reaction force ECU 70.

Here, the gain output by the sports gain calculation process M20 and the gain output by the normal gain calculation process M18 have different values for the same vehicle speed V. For example, when the vehicle speed V is the same, the gain output by the sports gain calculation process M20 may be set to be a larger value than the gain output by the normal gain calculation process M18.

The gain selection process M22 is a process for selecting one of the output of the normal gain calculation process M18 and the output of the sports gain calculation process M20, depending on the operating state of the user interface 86. The gain selection process M22 is a process executed in the reaction force ECU 70.

The change amount guard process M24 is a process that alleviates the change in the gain G output by the gain selection process M22. The change amount guard process M24 is a process executed in the reaction force ECU 70.

The multiplication process M26 is a process of multiplying the torsion angle Δθh by the gain G output by the change amount guard process M24. The multiplication process M26 is a process executed in the reaction force ECU 70.
The addition process M28 is a process of calculating the control steering angle θhc by adding the output value of the multiplication process M26 to the steering angle θh. The addition process M28 is a process executed in the reaction force ECU 70.

The target pinion angle calculation process M30 is a process for calculating the target pinion angle θp* using the control steering angle θhc and the vehicle speed V as input. The control steering angle θhc is the pinion angle θp corresponding to the steering angle θh. In other words, when a predetermined steering angle ratio is used, the pinion angle θp corresponds to the steering angle θh. In the target pinion angle calculation process M30, the steering angle ratio is made variable according to the vehicle speed V. Therefore, the target pinion angle θp* may be different from the control steering angle θhc. The target pinion angle calculation process M30 is a process executed in the steering ECU 90.

The pinion angle feedback process M34 is a process of calculating a steering torque command value Tt*, which is a torque command value of the steering motor 60, in order to perform feedback control of the pinion angle θp to the target pinion angle θp*. The pinion angle feedback process M34 is a process executed in the steering ECU 90.

The steering operation process M36 is a process of inputting the steering torque command value Tt*, the currents iu2, iv2, iw2, and the rotation angle θb, and outputting the operation signal MSt to the steering inverter 62. The steering operation process M36 includes a process of calculating a dq-axis current command value based on the steering torque command value Tt*. Further, the steering operation process M36 includes a process of calculating the dq-axis current based on the currents iu2, iv2, iw2 and the rotation angle θb. The process also includes a process of calculating an operation signal MSt to operate the steering inverter 62 so that the dq-axis current becomes the command value. The steering operation process M36 is a process executed in the steering ECU 90.

FIG. 3 shows the procedure of the change amount guard processing M24. 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 period. Note that in the following, the step number of each process is expressed by a number prefixed with "S".

In the series of processes shown in FIG. 3, the PU 72 first obtains the gain G (S10). Note that in FIG. 3, "G(n)" is written. Here, the number in parentheses after the gain G indicates the sampling number. In the following, it is assumed that the more recently sampled gain G has a larger sampling number. Next, the PU 72 determines whether the value of the mode variable has been switched (S12). The mode variable is a variable that identifies normal mode and sports mode. That is, the process of S12 is a process of determining whether or not one of the two modes, normal mode and sports mode, has been switched to the other by operating the user interface 86. If the PU 72 determines that the value of the mode variable has been switched (S12: YES), the process proceeds to S14. In the process of S14, the PU 72 substitutes the value obtained by subtracting the previous value "G(n-1)" from the current value "G(n)" of the gain G to the offset amount initial value ΔGb, and also sets the offset amount to the offset amount ΔG. Substitute the initial quantity value ΔGb.

The PU 72 determines whether the offset amount initial value ΔGb is positive or not when completing the process of S14 and when making a negative determination in the process of S12 (S16). If the PU 72 determines that it is positive (S16: YES), it substitutes the larger of the value obtained by subtracting "ΔGb/N" from the offset amount ΔG and zero into the offset amount ΔG (S18). Here, "N" is an integer of "2" or more. On the other hand, when determining that the offset amount initial value ΔGb is less than or equal to zero (S16: NO), the PU 72 sets the offset amount to the smaller of zero and the value obtained by subtracting "ΔGb/N" from the offset amount ΔG. Substitute it into ΔG (S20).

When completing the processes of S18 and S20, the PU 72 substitutes the value obtained by subtracting the offset amount ΔG from the gain G to the gain G (S22).
Note that, when completing the process of S22, the PU 72 temporarily ends the series of processes shown in FIG.

"Actions and effects of this embodiment"
The PU 72 gradually changes the gain G when the driver switches from one of the two modes, the sport mode and the normal mode, to the other. Thereby, it is possible to suppress a sudden change in the target pinion angle θp* due to the above switching.

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

In the first embodiment, the gradual change speed of the gain G is set in accordance with the magnitude of the initial offset amount ΔGb. In contrast, in this embodiment, the gradual change speed is set to a fixed value.

FIG. 4 shows the procedure of the change amount guarding process M24 according to this embodiment. The process shown in FIG. 4 is realized by the PU 72 repeatedly executing a program stored in the storage device 74 at a predetermined period, for example. Note that in FIG. 4, processes corresponding to those shown in FIG. 3 are given the same step numbers for convenience, and the description thereof will be omitted.

In the series of processes shown in FIG. 4, when completing the process of S10, the PU 72 calculates the absolute value of the value obtained by subtracting the previous value "G(n-1)" from the current value "G(n)" of the gain G. It is determined whether or not it is larger than a threshold value Δth (S12a). The threshold value Δth is set to a value larger than the upper limit of the change in the gain G that can occur when the mode is constant in the execution cycle of the process shown in FIG. If the PU 72 determines that the value is larger than the threshold value Δth (S12a: YES), the process proceeds to S14. On the other hand, when the PU 72 determines that it is equal to or less than the threshold value Δth (S12a: NO), the process proceeds to S16.

Further, when the PU 72 makes an affirmative determination in the process of S16, it substitutes the larger of zero and the value obtained by subtracting the specified value Δ from the offset amount ΔG to the offset amount ΔG (S18a). It is desirable that the specified value Δ be a value smaller than the threshold value Δth. On the other hand, when determining that the initial offset amount ΔGb is less than or equal to zero (S16: NO), the PU 72 sets the offset amount ΔG to the smaller of zero and the value obtained by subtracting the specified value Δ from the offset amount ΔG. Substitute (S20a).

Note that when the PU 72 completes the processing of S18a and S20a, it moves to the processing of S22.
<Correspondence>
The correspondence relationship between the matters in the above embodiment and the matters described in the column of "Means for solving the problem" above is as follows. Below, the correspondence relationship is shown for each solution number listed in the "Means for solving the problem" column. [1] The angle variable corresponds to the target pinion angle θp*. The angle variable calculation process includes torsion angle calculation process M16, normal gain calculation process M18, sports gain calculation process M20, gain selection process M22, variation guard process M24, multiplication process M26, addition process M28, and target pinion angle calculation process M30. corresponds to The operation processing corresponds to pinion angle feedback processing M34 and steering operation processing M36. The gradual change processing corresponds to the processing in S16 to S22 in FIG. 3 and the processing in S16, S18a, S20a, and S22 in FIG. [2] The target steering angle variable corresponds to the target pinion angle θp*. [3] The basic turning angle indicated by the steering angle corresponds to the steering angle θh. The predetermined amount corresponds to the difference between the steering angle θh and the target pinion angle θp*. [4,5] The twist angle calculation process corresponds to the twist angle calculation process M16. The gain multiplication process corresponds to normal gain calculation process M18, sports gain calculation process M20, gain selection process M22, and multiplication process M26.

<Other embodiments>
Note that this embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

"About gradual change processing"
・In Figures 3 and 4, immediately after switching the mode variable, the gain G is shifted by the magnitude of "|ΔGb/N|" or the magnitude of the specified value Δ from the gain obtained by the process in S10. Not limited to. For example, immediately after switching the mode variable, the gain G may be set to a value equal to the previous value "G(n-1)".

- Gradual change processing is not limited to processing that guards against changes in gain. For example, as described in the "Angle Variable Calculation Process" section below, when the torsion angle Δθh is calculated according to the value of the mode variable, the process may be performed to gradually change the change in the torsion angle Δθh. This can be realized by replacing the gain G with the twist angle Δθh in the process of FIG. 3 or 4.

- The gradual change process is not limited to the process of gradually changing the change in the target pinion angle θp* by gradually changing the change in the control steering angle θhc. For example, the target pinion angle θp* itself outputted by the target pinion angle calculation process M30 may be corrected. This can be realized, for example, by replacing the gain G with the target pinion angle θp* output by the target pinion angle calculation process M30 in the process of FIG. 3 or 4.

- FIG. 3 illustrates setting the gradual change speed of the gradual change process according to the magnitude of the offset amount initial value ΔGb. Further, FIG. 4 illustrates an example in which the gradual change speed of the gradual change process is set to a constant value. However, it is not necessary to be either of these. For example, the gradual change speed may be variably set according to the steering angular speed, which is the speed at which the steering angle changes. Here, for example, when the magnitude of the steering angular velocity is large, the gradual change speed may be made larger than when it is small. Note that the steering angular velocity may be the rate of change of the steering angle θh, but is not limited thereto. For example, it may be a time change in the pinion angle θp or a time change in the target pinion angle θp*. Furthermore, for example, the gradual change speed may be variably set depending on the vehicle speed.

"About operation processing"
- Feedback control of the turning angle by pinion angle feedback processing M34 is not essential. For example, the manipulated variable for open loop control based on the target pinion angle θp* as the target value of the steering angle may be set as the steering torque command value Tt*. Further, for example, the steering torque command value Tt* may be the sum of the feedback operation amount and the open-loop control operation amount.

- The control method for the steering motor 60 is not limited to dq-axis current feedback processing. For example, when a DC motor is used as the steering motor 60 and the drive circuit is an H-bridge circuit, it is sufficient to simply control the current flowing through the steering motor 60.

- As illustrated in the column "About angle variables" below, it is not essential that the operation process input the value of the target turning angle variable.
"About angle variable calculation process"
- It is not essential to calculate the control steering angle θhc according to the vehicle speed V. For example, in the process illustrated in FIG. 2, different fixed values of gains G may be used depending on whether the mode is normal mode or sports mode.

- The torsion angle Δθh is not limited to one that is map-calculated using the steering torque Th as an input variable. For example, the torsion angle Δθh may be map-calculated using map data in which the steering torque Th, the value of the mode variable, and the vehicle speed are used as input variables, and the torsion angle Δθh is used as an output variable. In that case, the normal gain calculation process M18, the sports gain calculation process M20, the gain selection process M22, the change amount guard process M24, and the multiplication process M26 may be deleted.

- The target pinion angle calculation process M30 may be a process of variably setting the steering angle ratio according to the detected value of the yaw rate sensor in addition to the vehicle speed V.
- It is not essential to provide the target pinion angle calculation process M30. In other words, the control steering angle θhc may be set as the target pinion angle θp*.

"About the target steering angle variable"
The target turning angle variable is not limited to the target pinion angle θp*. For example, it may be the target value of the steering angle of the steered wheels 44, that is, the turning angle of the tire itself. For example, the target value of the displacement amount of the steered shaft 40 may be used.

"About angle variables"
- The angle variable is not limited to the target steering angle variable. For example, when adopting a process of outputting the steering torque command value Tt* as an open loop operation amount according to the control steering angle θhc and the vehicle speed V in place of the pinion angle feedback process M34, the angle variable is The steering angle becomes θhc.

"About mode variables"
- The mode variable is not limited to a variable that distinguishes between the two values of sports mode and normal mode.

“About the steering ECU”
- The steering ECU is not limited to the reaction force ECU 70 and the steering ECU 90. For example, they may be integrally formed.

- The steering ECU is not limited to one that includes a PU and a storage device and executes software processing. For example, a dedicated hardware circuit such as an ASIC may be provided to process at least a part of what was processed by software in the above embodiments by hardware. That is, the control device may have any of the following configurations (a) to (c). (a) It includes a processing device that executes all of the above processing according to a program, and a program storage device such as a storage device that stores the program. (b) It includes a processing device and a program storage device that execute part of the above processing according to a program, and a dedicated hardware circuit that executes the remaining processing. (c) A dedicated hardware circuit is provided to execute all of the above processing. Here, there may be a plurality of software execution devices including a processing device and a program storage device, and a plurality of dedicated hardware circuits.

"About the steering actuator"
- As the steering actuator At, for example, one in which the steering motor 60 is disposed coaxially with the steering shaft 40 may be employed. Alternatively, for example, one connected to the steering shaft 40 via a belt-type speed reducer using a ball screw mechanism may be adopted.

"About the steering system"
- The steering system that can change the relationship between the steering angle and the turning angle is not limited to a steering system in which power transmission between the steering wheel 12 and the turning wheels 44 is cut off. For example, by using a variable gear as a gear that enables power transmission between the steering wheel 12 and the steered wheels 44, a steering system that can change the relationship between the steering angle and the steered angle may be configured.

DESCRIPTION OF SYMBOLS 10... Steering device 12... Steering wheel 14... Steering shaft 16... Reduction mechanism 20... Reaction force 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 ... Reaction force ECU
90...Steering ECU

Claims (5)

Applied to vehicles equipped with a steering system that can change the relationship between the steering angle and the turning angle,
The steering angle is a rotation angle of a steering wheel,
The steering angle is a turning angle of a steering wheel of the vehicle,
configured to perform angle variable calculation processing, operation processing, and gradual change processing;
The angle variable calculation process is a process of calculating the value of the angle variable according to the value of the mode variable,
The mode variable is a variable indicating the driver's preference for the operating feeling of the vehicle,
The angle variable is a variable indicating the steering angle,
The operation process is a process of operating the steering system using the value of the angle variable as input,
In the gradual change process, when the value of the mode variable is changed, the value of the angle variable that is input to the operation process is changed from the value of the angle variable that corresponds to the value of the mode variable before the change. A steering control device that performs a process of gradually shifting the angle variable to a value that corresponds to a later value of the mode variable. The steering control device according to claim 1, wherein the angle variable is a target turning angle variable that is a variable indicating a target value of the turning angle. The angle variable calculation process is a process of calculating the value of the target turning angle variable by shifting the value of the target turning angle variable by a predetermined amount with respect to the basic turning angle indicated by the steering angle. and the process of variably setting the predetermined amount according to the value of the mode variable,
The gradual change process gradually changes the predetermined amount according to the value of the mode variable before the change to the predetermined amount according to the value of the mode variable after the change. 3. The process of gradually shifting the target turning angle variable from the value of the target turning angle variable corresponding to the value of the mode variable to the value of the target turning angle variable corresponding to the changed value of the mode variable. steering control device. The angle variable calculation process includes a twist angle calculation process and a gain multiplication process,
The torsion angle calculation process is a process of calculating a torsion angle according to a detected value of torque input to the steering wheel,
The gain multiplication process is a process of calculating the predetermined amount by multiplying the torsion angle by a gain, and is a process of variably setting the gain according to the value of the mode variable,
The gradual change process is performed by gradually changing the gain according to the value of the mode variable before the change to the gain according to the value of the mode variable after the change, thereby changing the mode before the change. 4. The steering control device according to claim 3, wherein the process is to gradually shift from the predetermined amount depending on the value of the variable to the predetermined amount depending on the value of the mode variable after the change. The gain multiplication process is a process of variably setting the gain according to the vehicle speed, and includes a process of setting the gain to a different size depending on the value of the mode variable even if the vehicle speed is the same. The steering control device according to claim 4.

Images