JP7484681B2 - Steering method and steering device - Google Patents

Description

The present invention relates to a steering method and a steering device.

Patent Document 1 proposes a steer-by-wire steering device that calculates a target steering angle of the steered wheels based on the steering angle of the steering wheel, controls an electric motor to steer the steered wheels so that the actual steering angle of the steered wheels becomes the target steering angle, and applies a steering reaction force to the steering wheel according to the steering angle.

JP 2016-137215 A

In a steer-by-wire steering device, the speed at which the vehicle's yaw rate changes as expected by the driver differs from the speed at which the vehicle's actual yaw rate changes, which can give the driver a sense of discomfort.
An object of the present invention is to alleviate the discomfort felt by a driver in a steer-by-wire steering device due to a difference between the rate of change of the vehicle's yaw rate that the driver expects and the rate of change of the vehicle's actual yaw rate.

In a steering method according to one aspect of the present invention, a steering angle of a steering wheel is detected, a target steering angle of the steered wheels is calculated according to the detected steering angle, an actual steering angle of the steered wheels is detected, the steered wheels are steered so that the actual steering angle and the target steering angle match, a first reaction force command value is calculated as a command value of a steering reaction force to be applied to the steering wheel based on the actual steering angle, the target steering angle, or the steering angle, an actual yaw rate of the vehicle is detected, a rate of change of the target yaw rate of the vehicle according to a change in the first reaction force command value is calculated, a speed deviation is calculated as the difference between the rate of change of the actual yaw rate and the rate of change of the target yaw rate, a reaction force correction value according to the speed deviation is added to the first reaction force command value to calculate a second reaction force command value, and a steering reaction force according to the second reaction force command value is applied to the steering wheel.

The present invention can mitigate the discomfort felt by the driver in a steer-by-wire steering device due to the difference between the rate of change in the vehicle's yaw rate that the driver expects and the rate of change in the vehicle's actual yaw rate.

1 is a schematic configuration diagram of an example of a steering device according to an embodiment; 1A is a schematic diagram of an example of change in steering force over time; FIG. 1B is a schematic diagram of change in steering angle depending on the steering force of FIG. 1A; FIG. 1C is a schematic diagram of change in actual steering angle over time when controlled to match a target steering angle based on the steering angle of FIG. 1B; FIG. 1D is a schematic diagram of change in steering force over time for causing the change in steering angle of FIG. 1C; FIG. 1E is a schematic diagram of change in self-aligning torque (SAT) generated by the steering angle of FIG. 1C; and FIG. 1F is a schematic diagram of change in yaw rate generated by the steering angle of FIG. FIG. 2 is a block diagram of an example of a functional configuration of a controller according to the first embodiment. 1A is a schematic diagram of a time change in a target steering angle, FIG. 1B is a schematic diagram of a time change in an actual steering angle of a steered wheel, FIG. 1C is a schematic diagram of a steering reaction force command value based on the actual steering angle of FIG. 1B (solid line) and a schematic diagram of a steering reaction force command value corrected in accordance with a speed deviation of FIG. 1F (dashed line), FIG. 1D is a schematic diagram of a time change in an actual yaw rate due to a change in an actual steering angle of FIG. 1B, FIG. 1E is a schematic diagram of a speed change rate of an actual yaw rate of FIG. 1D (solid line) and a schematic diagram of a speed change rate of a target yaw rate in accordance with a change in a steering reaction force command value (solid line) of FIG. 1C (dashed line), and FIG. 1F is a schematic diagram of a speed deviation of a speed change rate of a yaw rate of FIG. 4A is a block diagram of an example of a functional configuration of a target yaw angular acceleration calculation unit, and FIG. 4B is a characteristic diagram of an example of a tire lateral force determined by a lateral force determination unit. 4 is a flowchart of an example of a steering method according to the first embodiment. FIG. 11 is a block diagram of an example of a functional configuration of a controller according to a second embodiment. 1A is a schematic diagram of a time change in a target steering angle (solid line) and a schematic diagram of a target steering angle corrected in accordance with a speed deviation (dashed line) of (f), (b) is a schematic diagram of a time change in an actual steering angle of a steered wheel, (c) is a schematic diagram of a steering reaction force command value based on the actual steering angle of (b), (d) is a schematic diagram of a time change in an actual yaw rate due to a change in the actual steering angle of (b), (e) is a schematic diagram of a speed change rate of the actual yaw rate of (d) (solid line) and a schematic diagram of a speed change rate of a target yaw rate corresponding to a change in the steering reaction force command value of (c) (dashed line), and (f) is a schematic diagram of a speed deviation of the speed change rate of the yaw rate of (e). 10 is a flowchart of an example of a steering method according to a second embodiment. FIG. 13 is a block diagram of an example of a functional configuration of a controller according to a third embodiment. 1A is a characteristic diagram of an example of a first gain according to vehicle speed, FIG. 1B is a schematic diagram showing the difference in steering reaction force command value depending on vehicle speed, FIG. 1C is a characteristic diagram of an example of a second gain according to vehicle speed, and FIG. 1D is a schematic diagram showing the difference in target steering angle depending on vehicle speed. 1A is a characteristic diagram of an example of a first gain according to lateral acceleration, FIG. 1B is a schematic diagram showing the difference in steering reaction force command value due to lateral acceleration, FIG. 1C is a characteristic diagram of an example of a second gain according to lateral acceleration, and FIG. 1D is a schematic diagram showing the difference in target steering angle due to lateral acceleration.

Below, an embodiment of the present invention will be described with reference to the drawings. Note that each drawing is a schematic view and may differ from the actual product. Furthermore, the embodiment of the present invention shown below is an example of an apparatus and method for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the structure, arrangement, etc. of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

First Embodiment
(composition)
FIG. 1 is a schematic diagram of an example of a steering device according to an embodiment mounted on a vehicle.
The steering device of the embodiment includes a steering unit 31 that receives steering input from the driver, a steering unit 32 that steers left and right front wheels 34FL, 34FR, which are steered wheels, a backup clutch 33, and a controller 11.
This steering device employs a steer-by-wire (SBW) system in which the steering unit 31 and the steered unit 32 are mechanically separated when the backup clutch 33 is released. In the following description, the left and right front wheels 34FL, 34FR may be referred to as "steered wheels 34".

The steering unit 31 includes a steering wheel 31a, a column shaft 31b, a reaction force actuator 31c, a steering angle sensor 31e, and a current sensor 31f.
On the other hand, the steering unit 32 includes a pinion shaft 32a, a steering gear 32b, a rack gear 32c, a steering rack 32d, a steering actuator 32e, a steering angle sensor 32g, and a current sensor 32h.

The steering wheel 31a of the steering unit 31 is applied with a reaction torque by the reaction actuator 31c and rotates in response to the input of a steering torque applied by the driver. Note that in this specification, the reaction torque applied to the steering wheel by the actuator may be referred to as "steering reaction torque."
The column shaft 31b rotates integrally with the steering wheel 31a.

Below, an example in which the reaction force actuator 31c is an electric motor will be described, but the reaction force actuator 31c is not limited to an electric motor. The reaction force actuator 31c can be any type of actuator that converts the signal output by the controller 11 into physical motion. The reaction force actuator 31c has an output shaft that is arranged coaxially with the column shaft 31b.

The reaction force actuator 31c is driven by a reaction force current Ism output from the controller 11, and outputs a rotational torque to be applied to the steering wheel 31a to the column shaft 31b. By applying the rotational torque, a steering reaction force torque is applied to the steering wheel 31a.
The steering angle sensor 31e detects the column shaft rotation angle, that is, the steering angle θs (handle angle) of the steering wheel 31a.
The current sensor 31f detects a reaction force current, which is a drive current for the reaction force actuator 31c, and inputs the detected reaction force current Isd to the controller 11.

On the other hand, the steering gear 32b of the steering unit 32 meshes with the rack gear 32c and steers the steered wheels 34 in response to the rotation of the pinion shaft 32a. As the steering gear 32b, for example, a rack-and-pinion type steering gear or the like may be adopted.
The backup clutch 33 is provided between the column shaft 31b and the pinion shaft 32a. When the backup clutch 33 is in a released state, it mechanically separates the steering unit 31 from the steered unit 32, and when the backup clutch 33 is in an engaged state, it mechanically connects the steering unit 31 to the steered unit 32.

The backup clutch 33 is normally in a released state, such as when the vehicle is running or the ignition switch is on, and is engaged when an abnormality occurs in the system, such as an abnormality in the steering actuator 32e or the reaction force actuator 31c, or when the vehicle's ignition switch is off (for example, when parked), and is normally in a released state. For this reason, in the following description, the backup clutch 33 is in a released state, and the steering wheel 31a and the steering unit 32 are described as being mechanically separated.

The steering actuator 32e is driven by a steering current Itm output from the controller 11, and outputs a steering torque for steering the steered wheels 34 to the steering rack 32d.
Although an example in which the steering actuator 32e is an electric motor will be described below, the steering actuator 32e is not limited to being an electric motor. The steering actuator 32e can be any type of actuator that converts a signal output by the controller 11 into physical motion.
The steering actuator 32e has an output shaft that is connected to the rack gear 32c via a reducer.

The steering angle sensor 32g detects an actual steering angle θt, which is the actual steering angle of the steered wheels 34.
The current sensor 32h detects the steering current which is the drive current of the steering actuator 32e, and inputs it to the controller 11 as the detected steering current Itd.
The vehicle speed sensor 16 detects the wheel speed of the vehicle on which the steering device of the embodiment is mounted, and calculates the vehicle speed Vv of the vehicle based on the wheel speed. The vehicle speed sensor 16 inputs the vehicle speed Vv to the controller 11.

The yaw rate sensor 17 detects an actual yaw rate γa, which is the actual yaw rate of the vehicle on which the steering device of the embodiment is mounted, and inputs the detected actual yaw rate γa to the controller 11 .
The acceleration sensor 18 detects a lateral acceleration Gy acting on a vehicle equipped with the steering device of the embodiment, and inputs the detected lateral acceleration Gy to the controller 11 .

The controller 11 is an electronic control unit (ECU) that controls the turning of the steered wheels and the reaction force of the steering wheel. In this specification, the "reaction force control" refers to the control of the steering reaction force torque applied to the steering wheel 31a by an actuator such as the reaction force actuator 31c.
The controller 11 includes a processor 20, a storage device 21, and peripheral components such as a drive circuit 22. The processor 20 may be, for example, a CPU (Central Processing Unit) or an MPU (Micro-Processing Unit).

The storage device 21 may include a semiconductor storage device, a magnetic storage device, and an optical storage device. The storage device 21 may include a register, a cache memory, a memory such as a ROM (Read Only Memory) and a RAM (Random Access Memory) used as a main memory device.
The information processing executed by the controller 11 and described below may be realized, for example, by the processor 20 executing a computer program stored in the storage device 21 of the controller 11 .

The information processing performed by the controller 11 and described below may be executed by a functional logic circuit configured in a general-purpose semiconductor integrated circuit. For example, the controller 11 may have a programmable logic device (PLD) such as a field programmable gate array (FPGA).

Furthermore, the controller 11 includes a drive circuit 22 for generating a reaction force current Ism for driving the reaction force actuator 31c and a steering current Itm for driving the steering actuator 32e.
The drive circuit 22 may include, for example, switching elements for controlling the reaction force current Ism and the steering current Itm.

The controller 11 calculates the steering reaction force command value frr according to the actual turning angle θt. For example, the larger the actual turning angle θt, the larger the steering reaction force command value frr is calculated. Note that instead of the actual turning angle θt, the steering reaction force command value frr may be calculated according to the target turning angle θtr or the steering angle θs described below. In the following embodiment, the steering reaction force command value frr is calculated according to the actual turning angle θt. The steering reaction force command value frr is a command value for the steering reaction force torque applied to the steering wheel 31a. The controller 11 outputs a reaction force current Ism that generates a steering reaction force torque according to the steering reaction force command value frr to the reaction force actuator 31c, and applies the steering reaction force torque to the steering wheel 31a.

The controller 11 also calculates the target steering angle θtr, which is the target value of the steering angle of the steered wheels 34, according to the steering angle θs detected by the steering angle sensor 31e. The controller 11 calculates a steering force command value ftr for matching the actual steering angle θt to the target steering angle θtr, based on the difference between the actual steering angle θt detected by the steering angle sensor 32g and the target steering angle θtr. The steering force command value ftr is a command value for the steering torque that steers the steered wheels 34.

The steering force command value ftr is calculated so that the larger the difference (θtr-θt) between the actual steering angle θt and the target steering angle θtr, the larger the value. The steering force command value ftr is calculated, for example, by multiplying the difference (θtr-θt) between the actual steering angle θt and the target steering angle θtr by a predetermined gain. Alternatively, the steering force command value ftr for the difference (θtr-θt) between the actual steering angle θt and the target steering angle θtr may be stored in advance as a steering force map, and the steering force command value ftr may be calculated by referring to the steering force map based on the calculated (θtr-θt).
The controller 11 outputs a steering current Itm that generates a steering torque corresponding to the steering force command value ftr to the steering actuator 32e, thereby steering the steered wheels 34.

As described above, the steering device of this embodiment calculates the target turning angle θtr based on the steering angle θs of the steering wheel 31a, and steers the steered wheels 34 so that the actual turning angle θt coincides with the target turning angle θtr.
In addition, a steering reaction force corresponding to the actual steering angle θt is applied to the steering wheel 31a.

Here, when the driver feels a steering reaction force when steering, the driver predicts what type of vehicle behavior will occur depending on the magnitude of the steering reaction force.
As described above, when the steered wheels 34 are steered so that the actual steering angle θt coincides with the target steering angle θt, and a steering reaction force corresponding to the actual steering angle θt is applied to the steering wheel 31a, the rate of change of the vehicle's yaw rate that the driver expects depending on the rate of change of the steering reaction force differs from the rate of change of the actual yaw rate γa, which may cause the driver to feel uncomfortable.
For example, the driver may feel uncomfortable if the rate of change of the actual yaw rate γa is too fast compared to the rate of change of the steering reaction force. The reason for this will be explained below.

FIG. 2A is a schematic diagram showing an example of a change over time in steering force applied by a driver, and FIG. 2B is a schematic diagram showing a steering angle θs that changes due to the steering force of FIG. 2A.
When the driver increases the steering force from time t1 to time t2, the steering angle θs increases accordingly.
FIG. 2C is a schematic diagram showing the change over time of the actual steering angle θt when the actual steering angle is controlled so as to coincide with the target steering angle based on the steering angle of FIG. 2B.

In a steer-by-wire system, servo control is performed to match the target steering angle θtr calculated from the steering angle θs with the actual steering angle θt. This reduces the delay in the actual steering angle θt relative to the steering angle θs, compared to conventional steering devices that transmit steering torque to the steered wheels by connecting a shaft. In other words, the delay in the actual steering angle θt relative to the steering force applied by the driver is reduced.

The solid line in Fig. 2(d) shows a schematic diagram of the steering force for producing the steering angle change in Fig. 2(c) In Fig. 2(d), for comparison, a dashed line shows a waveform showing the time change of the actual steering angle θt.
Immediately after steering starts (i.e., immediately after the actual steering angle θt starts to change), the slip angle, which is the angular difference between the direction of the steered wheels 34 and the traveling direction of the steered wheels 34, becomes large. Accordingly, the lateral force generated in the tire increases transiently. After that, the lateral force converges to a magnitude corresponding to the actual steering angle θt.
The steering force changes in the same way as the lateral force, and it becomes transiently large immediately after the start of steering and then converges to a magnitude corresponding to the actual steering angle θt. Therefore, the change in the steering force immediately after the start of steering is faster than the change in the actual steering angle θt.

The solid line in Fig. 2(e) shows a schematic diagram of the change over time of the SAT (Self-Aligning Torque) caused by the steering angle in Fig. 2(c), and the solid line in Fig. 2(f) shows a schematic diagram of the change over time of the actual yaw rate γa caused by the steering angle in Fig. 2(c). For comparison, the dashed lines in Fig. 2(e) and Fig. 2(f) show waveforms showing the change over time of the actual steering angle θt.
The self-aligning torque and the actual yaw rate γa also become transiently large immediately after the start of steering, similar to the steering force. Therefore, the changes in the self-aligning torque and the actual yaw rate γ immediately after the start of steering are also faster than the changes in the actual steering angle θt.

In this way, the change in the actual yaw rate γa immediately after the start of steering is faster than the change in the actual steering angle θt.
For this reason, when a steering reaction force corresponding to the actual turning angle θt is applied, the driver may feel that the rate of change of the actual yaw rate γa is too fast compared to the rate of change of the steering reaction force, which may give the driver a sense of discomfort.

Therefore, the controller 11 of the first embodiment calculates a speed deviation ΔV, which is the difference between the rate of change of the target yaw rate γr of the vehicle expected by the driver and the rate of change of the actual yaw rate γa, based on the rate of change of the steering reaction force, and applies a steering reaction force to the steering wheel 31a to which a correction value corresponding to the speed deviation ΔV has been added.
In this way, by adding the correction value according to the speed deviation ΔV between the target yaw rate γr and the actual yaw rate γa to the steering reaction force, the difference between the speed of change of the vehicle yaw rate expected by the driver and the speed of change of the actual yaw rate γa can be reduced, thereby suppressing the discomfort felt by the driver due to the difference in the speed of change of these yaw rates.

Next, a description will be given of an example of the functional configuration of the controller 11. Fig. 3 is a block diagram of an example of the functional configuration of the controller 11 according to the first embodiment.
The controller 11 includes a target steering angle calculation unit 40, subtractors 41 and 47, a steering angle servo control unit 42, a steering motor drive unit 43, a reaction force command value calculation unit 44, a target yaw angular acceleration calculation unit 45, a differentiator 46, a gain multiplication unit 48, an adder 49, and a reaction force motor drive unit 50.

The target turning angle calculation section 40 calculates the target turning angle θtr in accordance with the steering angle θs. For example, the target turning angle calculation section 40 may calculate the target turning angle θtr by multiplying the steering angle θs by the angle ratio Ra.
The target turning angle calculation section 40 may dynamically change the angle ratio Ra. For example, the target turning angle calculation section 40 may change the angle ratio Ra in accordance with at least the vehicle speed Vv.

Alternatively, the target steering angle θtr relative to the steering angle θs may be stored in advance as a steering angle map, and the target steering angle θtr may be calculated by referring to the steering angle map based on the detected actual steering angle θs. In addition, the relationship of the target steering angle θtr relative to the steering angle θs may be changed according to the vehicle speed Vv by storing multiple steering angle maps according to the vehicle speed Vv.

The subtractor 41 calculates the turning angle deviation Δθ=θt−θt, which is the difference obtained by subtracting the actual turning angle θt detected by the turning angle sensor 32g from the target turning angle θtr calculated by the target turning angle calculation section 40.
The steering angle servo control unit 42 calculates the steering force command value ftr by servo control for reducing the steering angle deviation Δθ.

The steering motor drive unit 43 generates a steering current Itm to be output to the steering actuator 32e by torque feedback control that matches the actual steering torque estimated from the detected steering current Itd detected by current sensor 32h with the steering force command value ftr output from the steering angle servo control unit 42, and outputs the steering current Itm to the steering actuator 32e.
The steering current Itm to be output to the steering actuator 32e may be generated by current feedback control that matches the detected steering current Itd with a drive current corresponding to the steering force command value ftr.

When the steering current Itm flows through the steering actuator 32e, the steering actuator 32e generates a steering torque and steers the steered wheels 34.
FIG. 4(a) is a schematic diagram of an example of the change over time of the target steering angle θtr, and FIG. 4(b) is a schematic diagram of an example of the change over time of the actual steering angle θt of the steered wheels 34 when steered according to the target steering angle θtr of FIG. 4(a).

3, the reaction force command value calculation unit 44 calculates a basic steering reaction force command value frr1, which is a command value for the steering reaction force applied to the steering wheel 31a, based on at least the actual turning angle θt.
The basic steering reaction force command value frr1 may be calculated based on the steering angle θs or the target steering angle θtr instead of the actual steering angle θt.

In addition, the reaction force command value calculation unit 44 may calculate the basic steering reaction force command value frr1 in accordance with at least one of the vehicle speed Vv, the lateral acceleration Gy generated in the vehicle, the actual yaw rate γa, and the detected steering current Itd in addition to the actual steering angle θt, the target steering angle θtr, or the steering angle θs.
The solid line in FIG. 4C is a schematic diagram showing an example of a change over time in the basic steering reaction force command value frr1 calculated by the reaction force command value calculation section 44 in accordance with the actual steering angle θt in FIG. 4B.

Refer to FIG. 3. The target yaw angular acceleration calculation unit 45 calculates the rate of change (dγr/dt) of the target yaw rate of the vehicle according to the time change of the basic steering reaction force command value frr1. γr indicates the target yaw rate of the vehicle, and dγr/dt indicates the time derivative of the target yaw rate γr (i.e., the yaw angular acceleration). Hereinafter, the rate of change of the target yaw rate γr may be referred to as the "target yaw angular acceleration."

For example, the target yaw angular acceleration calculation unit 45 calculates the yaw angular acceleration that a standard driver would expect in response to a change over time in the basic steering reaction force command value frr1 as the target yaw angular acceleration (dγr/dt).
Sensory evaluation has shown that the cutoff frequency of the yaw rate frequency response is preferably about 1 to 2 Hz, and it is preferable to calculate a target yaw angular acceleration (dγr/dt) that provides such a frequency response.
The dashed line in FIG. 4(e) is a schematic diagram of the target yaw angular acceleration (dγr/dt) calculated in accordance with the change over time in the basic steering reaction force command value frr1 in FIG. 4(c).

5A is a block diagram of an example of the functional configuration of the target yaw angular acceleration calculation unit 45. The target yaw angular acceleration calculation unit 45 includes a lateral force determination unit 45a, a target yaw rate calculation unit 45b, and a differentiator 45c.
The lateral force determining section 45a determines, based on the basic steering reaction force command value frr1, a front wheel tire lateral force Fy that generates a steering reaction force of a magnitude indicated by the basic steering reaction force command value frr1.

For example, the lateral force determining unit 45a may determine the front wheel tire lateral force Fy from the basic steering reaction force command value frr1 using a map that defines the relationship between the steering reaction force and the tire lateral force Fy.
5B shows an example of a map defining the relationship between the steering reaction force and the tire lateral force Fy. As shown in the figure, the tire lateral force Fy has a characteristic of monotonically increasing as the basic steering reaction force command value frr1 increases.
The lateral force determining section 45a may calculate the front wheel tire lateral force Fy from the basic steering reaction force command value frr1 using an arithmetic expression.

5A, the target yaw rate calculation unit 45b calculates the yaw rate that occurs when the front wheel tire lateral force Fy determined by the lateral force determination unit 45a occurs as a target yaw rate γr.
For example, the target yaw rate calculation unit 45b may calculate an ideal yaw rate when a tire lateral force Fy is generated in a specific vehicle model as the target yaw rate γr. For example, the target yaw rate calculation unit 45b may calculate the target yaw rate γr by multiplying the tire lateral force Fy by the following transfer function used as the vehicle model.

In the above equation, m and I are the mass and moment of inertia of the vehicle, V is the vehicle speed, lf and lr are the distances from the center of gravity to the front and rear wheel axles, Kr is the cornering stiffness of the rear wheels, and s is the Laplace transform symbol.
The target yaw rate calculation section 45b may dynamically set the parameters 2mVlf, mVI, and 2KrlrmV in the above equation in response to the vehicle speed Vv detected by the vehicle speed sensor 16 as variable parameters in response to the vehicle speed Vv.
The mass m of the vehicle may be detected based on the detection results of the load sensor, the amount of sinking of the suspension, etc., and the parameters 2mVlf, mVI, 2Kr(mlr ² +1), and 2KrlrmV in the above equation may be dynamically set according to the mass m.

The differentiator 45c calculates a target yaw angular acceleration (dγr/dt) by differentiating the target yaw rate γr calculated by the target yaw rate calculation unit 45b.
3, the differentiator 46 calculates the rate of change (dγa/dt) of the actual yaw rate γa by differentiating the actual yaw rate γa detected by the yaw rate sensor 17. The rate of change of the actual yaw rate γa may be referred to as the "actual yaw angular acceleration."
FIG. 4D is a schematic diagram of the actual yaw rate γa, and the solid line in FIG. 4E is a schematic diagram of the actual yaw angular acceleration (dγa/dt).

Refer to Fig. 3. The subtractor 47 subtracts the target yaw angular acceleration (dγr/dt) from the actual yaw angular acceleration (dγa/dt) to calculate the speed deviation ΔV = (dγa/dt) - (dγr/dt). Fig. 4(f) is a schematic diagram of the speed deviation ΔV.
3, the gain multiplication unit 48 multiplies the speed deviation ΔV by a first gain G1 to calculate a multiplication result as a reaction force correction value Cr.

The adder 49 calculates the steering reaction force command value frr obtained by correcting the basic steering reaction force command value frr1 by adding the reaction force correction value Cr. That is, the adder 49 calculates the sum of the basic steering reaction force command value frr1 and the reaction force correction value Cr as the steering reaction force command value frr.
The dashed line in Fig. 4C is a schematic diagram of an example of a change in the steering reaction force command value frr over time. By adding the reaction force correction value Cr, the steering reaction force command value frr rises faster than the basic steering reaction force command value frr1 by the length indicated by the arrow in the figure.

Please refer to Fig. 3. The reaction force motor drive unit 50 drives the reaction force actuator 31c based on the steering reaction force command value frr.
The reaction force motor drive unit 50 generates a reaction force current Ism to be output to the reaction force actuator 31c by torque feedback control that matches an actual steering reaction force torque estimated from the detected reaction force current Isd detected by the current sensor 31f with the steering reaction force command value frr output by the adder 49, and outputs the reaction force current Ism to the reaction force actuator 31c. The reaction force current Ism to be output to the reaction force actuator 31c may be generated by current feedback control that matches the detected reaction force current Isd with a drive current equivalent to the steering reaction force command value frr.

In this way, by correcting the steering reaction force command value in accordance with the speed deviation ΔV between the actual yaw angular acceleration (dγa/dt) and the target yaw angular acceleration (dγr/dt), the rise of the steering reaction force command value can be accelerated when the actual yaw angular acceleration (dγa/dt) is too fast compared to the vehicle yaw angular acceleration expected by the driver in accordance with the rate of change of the steering reaction force.
As a result, the yaw angular acceleration expected by the driver increases according to the rate of change of the steering reaction force, and the difference with the actual yaw angular acceleration (dγa/dt) decreases. This makes it possible to suppress the discomfort felt by the driver caused by the actual yaw angular acceleration (dγa/dt) being too fast compared to the rate of change of the steering reaction force.

In addition, the steering angular acceleration of the steering wheel 31a can be reduced by accelerating the rise of the steering reaction force command value. This reduces the actual yaw angular acceleration (dγa/dt), thereby suppressing the discomfort felt by the driver due to the actual yaw angular acceleration (dγa/dt) being too fast compared to the rate of change of the steering reaction force.

(motion)
FIG. 6 is a flowchart of an example of a steering method according to the first embodiment.
In step S1, the steering angle sensor 31e detects the steering angle θs of the steering wheel 31a.
In step S2, the target steering angle calculation section 40 of the controller 11 calculates the target steering angle θtr in accordance with the steering angle θs.

In step S3, the steering angle sensor 32g detects the actual steering angle θt, which is the actual steering angle of the steered wheels 34.
In step S4, the reaction force command value calculation unit 44 calculates a basic steering reaction force command value frr1 based on at least the actual turning angle θt. The basic steering reaction force command value frr1 may be calculated based on the steering angle θs or the target turning angle θtr.

In step S5, the yaw rate sensor 17 detects the actual yaw rate γa.
In step S6, the target yaw angular acceleration calculation unit 45 calculates the rate of change (dγr/dt) of the target yaw rate in accordance with the change over time of the basic steering reaction force command value frr1.
In step S7, the differentiator 46 calculates the change rate (dγa/dt) of the actual yaw rate γa by differentiating the actual yaw rate γa. The subtractor 47 calculates the speed deviation ΔV=(dγa/dt)-(dγr/dt) between the change rate (dγr/dt) of the target yaw rate and the change rate (dγa/dt) of the actual yaw rate γa.

In step S8, the gain multiplication unit 48 multiplies the speed deviation ΔV by the first gain G1 to calculate a reaction force correction value Cr. The adder 49 adds the reaction force correction value Cr to the basic steering reaction force command value frr1 to calculate the steering reaction force command value frr.
In step S9, the steering angle servo control unit 42 calculates a steering force command value ftr based on the steering angle deviation Δθ between the target steering angle θtr and the actual steering angle θt.

In step S10, the steering motor drive unit 43 drives the steering actuator 32e based on the steering force command value ftr to steer the steered wheels 34.
In step S11, the reaction force motor drive unit 50 drives the reaction force actuator 31c based on the steering reaction force command value frr to apply a steering reaction force torque to the steering wheel 31a.
The process then ends.

(Effects of the First Embodiment)
Steering angle sensor 31e detects steering angle θs of steering wheel 31a. Target steering angle calculation unit 40 calculates target steering angle θtr of steered wheels 34 according to the detected steering angle θs. Steering angle sensor 32g detects actual steering angle θt, which is the actual steering angle of steered wheels 34. Steering angle servo control unit 42 and steering motor drive unit 43 steer the steered wheels so that the actual steering angle θt and target steering angle θt match. Reaction force command value calculation unit 44 calculates a basic steering reaction force command value frr1, which is a command value for the steering reaction force applied to steering wheel 31a, based on the actual steering angle θt, the target steering angle θt, or the steering angle θs.

The yaw rate sensor 17 detects the actual yaw rate γa, which is the actual yaw rate of the vehicle. The target yaw angular acceleration calculation unit 45 calculates the rate of change (dγr/dt) of the target yaw rate of the vehicle according to the change in the basic steering reaction force command value frr1. The subtractor 47 calculates a speed deviation ΔV, which is the difference between the rate of change (dγa/dt) of the actual yaw rate and the rate of change (dγr/dt) of the target yaw rate. The adder 49 adds a reaction force correction value Cr according to the speed deviation ΔV to the first steering reaction force command value frr1 to calculate the steering reaction force command value frr. The steering motor drive unit 43 applies a steering reaction force according to the steering reaction force command value frr to the steering wheel 31a.

This makes it possible to hasten the rise of the steering reaction force command value when the actual yaw angular acceleration (dγa/dt) is too fast compared to the vehicle yaw angular acceleration expected by the driver according to the rate of change of the steering reaction force.
As a result, the yaw angular acceleration expected by the driver increases according to the rate of change of the steering reaction force, and the difference with the actual yaw angular acceleration (dγa/dt) decreases. This makes it possible to suppress the discomfort felt by the driver caused by the actual yaw angular acceleration (dγa/dt) being too fast compared to the rate of change of the steering reaction force.

In addition, the steering angular acceleration of the steering wheel 31a can be reduced by accelerating the rise of the steering reaction force command value. This reduces the actual yaw angular acceleration (dγa/dt), thereby suppressing the discomfort felt by the driver due to the actual yaw angular acceleration (dγa/dt) being too fast compared to the rate of change of the steering reaction force.

Second Embodiment
(composition)
7 is a block diagram of an example of the functional configuration of the controller 11 of the second embodiment. The controller 11 of the second embodiment has functions similar to those of the controller 11 of the first embodiment. For this reason, the same reference numerals are used for the same components.
The controller 11 in the second embodiment reduces the target steering angle θtr by a correction value corresponding to the speed deviation ΔV, thereby reducing the actual yaw angular acceleration (dγa/dt).
As a result, the difference between the rate of change of the vehicle yaw rate expected by the driver according to the rate of change of the steering reaction force and the rate of change of the actual yaw rate γa can be reduced, thereby suppressing the discomfort felt by the driver due to the difference in the rate of change of these yaw rates.

The target steering angle calculation section 40 of the second embodiment calculates a basic target steering angle θtr1 in accordance with the steering angle θs. The basic target steering angle θtr1 of the second embodiment is similar to the target steering angle θtr of the first embodiment.
In addition, the reaction force command value calculation unit 44 of the second embodiment calculates the steering reaction force command value frr based on at least the actual turning angle θt. The steering reaction force command value frr may be calculated based on the steering angle θs or the basic target turning angle θtr1 instead of the actual turning angle θt. The steering reaction force command value frr of the second embodiment is the same as the basic steering reaction force command value frr1 of the first embodiment.

The solid line in FIG. 8(a) is a schematic diagram of an example of the change over time of the basic target steering angle θtr1, FIG. 8(b) is a schematic diagram of an example of the change over time of the actual steering angle θt of the steered wheels 34, FIG. 8(c) is a schematic diagram of an example of the change over time of the steering reaction force command value frr, FIG. 8(d) is a schematic diagram of the actual yaw rate γa, the solid line in FIG. 8(e) is a schematic diagram of the actual yaw angular acceleration (dγa/dt), the dashed line in FIG. 8(e) is a schematic diagram of the target yaw angular acceleration (dγr/dt), and FIG. 8(f) is a schematic diagram of the speed deviation ΔV.

7, the controller 11 of the second embodiment includes a gain multiplication unit 51 and a subtractor 52.
The gain multiplication unit 51 multiplies the speed deviation ΔV by a second gain G2 to calculate a multiplication result as the steering angle correction value Ct.
The subtractor 52 calculates the target turning angle θtr obtained by correcting the basic target turning angle θtr1 by subtracting the turning angle correction value Ct. That is, the subtractor 52 calculates the difference obtained by subtracting the turning angle correction value Ct from the basic target turning angle θtr1 as the target turning angle θtr.

8C is a schematic diagram of an example of a change in the target turning angle θtr over time. By subtracting the turning angle correction value Ct, the rise of the target turning angle θtr is delayed compared to the basic target turning angle θtr1.
Subtractor 41 calculates steering angle deviation Δθ=θtr-θt, as in the first embodiment. Steering angle servo control section 42 calculates steering force command value ftr by servo control to reduce the steering angle deviation Δθ. Steering motor drive section 43 drives steering actuator 32e based on steering force command value ftr.

In this way, by correcting the target steering angle in accordance with the speed deviation ΔV between the actual yaw angular acceleration (dγa/dt) and the target yaw angular acceleration (dγr/dt), the rise of the target steering angle θtr can be delayed when the actual yaw angular acceleration (dγa/dt) is too fast compared to the vehicle yaw angular acceleration expected by the driver in accordance with the rate of change of the steering reaction force.
As a result, the actual yaw rate γa is delayed, and the difference between the yaw angular acceleration expected by the driver according to the change rate of the steering reaction force and the actual yaw angular acceleration (dγa/dt) is reduced, thereby suppressing the discomfort felt by the driver caused by the actual yaw angular acceleration (dγa/dt) being too fast compared to the change rate of the steering reaction force.

(motion)
FIG. 9 is a flowchart of an example of a steering method according to the second embodiment.
The process of step S21 is similar to step S1 in FIG.
In step S22, the target steering angle calculation section 40 of the controller 11 calculates a basic target steering angle θtr1 in accordance with the steering angle θs.

The process of step S23 is similar to step S3 in FIG.
In step S24, the reaction force command value calculation unit 44 calculates the steering reaction force command value frr based on at least the actual turning angle θt. The steering reaction force command value frr may be calculated based on the steering angle θs or the basic target turning angle θtr1.
The process of step S25 is similar to step S5 in FIG.
In step S26, the target yaw angular acceleration calculation unit 45 calculates the rate of change (dγr/dt) of the target yaw rate in accordance with the change over time of the steering reaction force command value frr.

The process of step S27 is similar to step S7 in FIG.
In step S28, gain multiplication section 51 calculates the multiplication result by multiplying speed deviation ΔV by second gain G2 as steering angle correction value Ct. Subtractor 52 calculates target steering angle θtr by dividing basic target steering angle θtr1 by steering angle correction value Ct.
The operations in steps S29 to S31 are similar to those in steps S9 to S11 in FIG.

(Effects of the Second Embodiment)
A target steering angle calculation unit 40 calculates a basic target steering angle θtr1 in accordance with the detected steering angle θs.
A subtractor 52 calculates a difference obtained by subtracting a steering angle correction value Ct corresponding to the speed deviation ΔV from a basic target steering angle θtr1 as a target steering angle θtr.

In this way, by correcting the target steering angle in accordance with the speed deviation ΔV between the actual yaw angular acceleration (dγa/dt) and the target yaw angular acceleration (dγr/dt), the rise of the target steering angle θtr can be delayed when the actual yaw angular acceleration (dγa/dt) is too fast compared to the vehicle yaw angular acceleration expected by the driver in accordance with the rate of change of the steering reaction force.
As a result, the actual yaw rate γa is delayed, and the difference between the yaw angular acceleration expected by the driver and the actual yaw angular acceleration (dγa/dt) according to the rate of change of the steering reaction force is reduced, thereby suppressing the discomfort felt by the driver caused by the actual yaw angular acceleration (dγa/dt) being too fast compared to the rate of change of the steering reaction force.

Third Embodiment
FIG. 10 is a block diagram of an example of the functional configuration of the controller 11 according to the third embodiment.
The controller 11 of the third embodiment has a configuration that combines the configuration of the controller 11 of the first embodiment and the configuration of the controller 11 of the second embodiment.
That is, the target turning angle calculation section 40 calculates the basic target turning angle θtr1 as in the second embodiment. Also, the reaction force command value calculation section 44 calculates the basic steering reaction force command value frr1 as in the first embodiment.

A gain multiplication unit 48 multiplies the speed deviation ΔV by a first gain G1 to calculate a multiplication result as a reaction force correction value Cr, and an adder 49 calculates the sum of the basic steering reaction force command value frr1 and the reaction force correction value Cr as a steering reaction force command value frr.
Gain multiplication unit 51 calculates the multiplication result by multiplying the speed deviation ΔV by a second gain G2 as the steering angle correction value Ct, and subtractor 52 calculates the difference obtained by subtracting the steering angle correction value Ct from the basic target steering angle θtr1 as the target steering angle θtr.

The reaction force motor drive unit 50 drives the reaction force actuator 31c based on the steering reaction force command value frr to apply a steering reaction force torque to the steering wheel 31a.
The steering motor drive unit 43 drives the steering actuator 32 e based on the steering force command value ft to steer the steered wheels 34 .
According to the third embodiment, it is possible to obtain the effects of the first embodiment and the effects of the second embodiment.

Furthermore, the gain multiplication unit 48 may dynamically set the first gain G1 in accordance with the vehicle speed Vv detected by the vehicle speed sensor 16 .
Fig. 11(a) is a characteristic diagram of an example of the first gain G1 according to the vehicle speed Vv. For example, the first gain G1 may be a gain that is larger when the vehicle speed Vv is high than when the vehicle speed Vv is low. For example, as shown in Fig. 11(a), the first gain G1 may be increased continuously as the vehicle speed Vv becomes higher. Also, the first gain G1 may be set to be larger in stages when the vehicle speed Vv is higher than a threshold value compared to when the vehicle speed Vv is lower than the threshold value.

11B is a schematic diagram showing the difference in the steering reaction force command value frr depending on the vehicle speed Vv. The dashed and dotted line shows the steering reaction force command value frr when not corrected with the reaction force correction value Cr, and the dashed and solid lines show the steering reaction force command value frr corrected with the reaction force correction value Cr calculated with the first gain G1 at low and high speeds, respectively.
When the vehicle speed Vv is high, the first gain G1 is larger than when the vehicle speed Vv is low, so that the steering reaction force command value frr can be increased more quickly as the vehicle speed Vv is high. This increases the force required for steering, thereby improving driving stability during high-speed driving.

In addition, the gain multiplication unit 51 may dynamically set the second gain G2 in accordance with the vehicle speed Vv detected by the vehicle speed sensor 16 .
Due to the characteristics of the tire rubber of the steered wheels 34, the higher the vehicle speed Vv, the smaller the fluctuation in the lateral force immediately after the start of steering described above becomes. Therefore, if the rise of the target steering angle θtr is delayed by the steering angle correction value Ct, when the vehicle speed Vv is high, the rise of the actual yaw rate γa will be delayed, and the vehicle behavior may be felt as sluggish.
Therefore, when the vehicle speed Vv is high, the second gain G2 may be set smaller than when the vehicle speed Vv is low, thereby reducing the turning angle correction value Ct, thereby reducing the amount of delay in the rise of the target turning angle θtr.
This makes it possible to prevent the vehicle behavior from feeling sluggish when the vehicle speed Vv is high.

Figure 11 (c) is a characteristic diagram of an example of the second gain G2 according to the vehicle speed Vv. For example, as shown in Figure 11 (c), the second gain G2 may be decreased continuously as the vehicle speed Vv increases. In addition, the second gain G2 may be set to be smaller in stages when the vehicle speed Vv is higher than a threshold value compared to when the vehicle speed Vv is lower than the threshold value.

11D is a schematic diagram showing the difference in target steering angle θtr depending on vehicle speed Vv. The dashed and dotted line shows the target steering angle θtr when not corrected with the steering angle correction value Ct, and the dashed and solid lines show the target steering angle θtr corrected with the steering angle correction value Ct calculated with the second gain G2 at low and high speeds, respectively.
When the vehicle speed Vv is high, the second gain G2 is smaller than when the vehicle speed Vv is low, so that the higher the vehicle speed Vv, the smaller the delay in the rise of the target steering angle θtr becomes.

In addition, the gain multiplication unit 48 may dynamically set the first gain G1 in accordance with the lateral acceleration Gy detected by the acceleration sensor 18 .
Fig. 12(a) is a characteristic diagram of an example of the first gain G1 according to the lateral acceleration Gy. For example, the first gain G1 may be a gain that is larger when the lateral acceleration Gy is large than when the lateral acceleration Gy is small. For example, as shown in Fig. 12(a), the first gain G1 may increase continuously as the lateral acceleration Gy increases. Also, when the lateral acceleration Gy is larger than a threshold value, the first gain G1 may be set to be larger in stages compared to when the lateral acceleration Gy is smaller than the threshold value.

12B is a schematic diagram showing the difference in the steering reaction force command value frr depending on the lateral acceleration Gy. The dashed dotted line shows the steering reaction force command value frr when not corrected with the reaction force correction value Cr.
The dashed line and the solid line indicate the steering reaction force command value frr corrected with the reaction force correction value Cr calculated with the first gain G1 when the lateral acceleration Gy is small and when it is large, respectively.
When the lateral acceleration Gy is large, the first gain G1 is larger than when the lateral acceleration Gy is small, so that the steering reaction force command value frr can be increased more quickly as the lateral acceleration Gy increases. This increases the force required for steering, thereby improving driving stability when a large lateral acceleration Gy is occurring.

In addition, the gain multiplication unit 51 may dynamically set the second gain G2 in accordance with the lateral acceleration Gy detected by the acceleration sensor 18.
In a situation where a high lateral acceleration Gy is occurring, if the rising of the target steering angle θtr is delayed due to the steering angle correction value Ct, causing a delay in the vehicle behavior, the steering feeling may deteriorate.
Therefore, when the lateral acceleration Gy is large, the second gain G2 may be set smaller than when the lateral acceleration Gy is small, thereby reducing the steering angle correction value Ct, thereby reducing the amount of delay in the rise of the target steering angle θtr.
This makes it possible to prevent deterioration of the steering feeling when a high lateral acceleration Gy is occurring.

Figure 12(c) is a characteristic diagram of an example of the second gain G2 according to the lateral acceleration Gy. For example, as shown in Figure 12(c), the second gain G2 may be decreased continuously as the lateral acceleration Gy increases. In addition, the second gain G2 may be set to be smaller in stages when the lateral acceleration Gy is greater than a threshold value compared to when the lateral acceleration Gy is less than the threshold value.

12D is a schematic diagram showing the difference in the target steering angle θtr depending on the lateral acceleration Gy. The dashed and dotted line shows the target steering angle θtr when not corrected with the steering angle correction value Ct, and the dashed and solid lines show the target steering angle θtr corrected with the steering angle correction value Ct calculated with the second gain G2 when the lateral acceleration Gy is small and large, respectively.
When the lateral acceleration Gy is large, the second gain G2 is smaller than when it is small, so that the higher the lateral acceleration Gy, the smaller the delay in the rise of the target steering angle θtr becomes.

(Effects of the Third Embodiment)
(1) The gain multiplication unit 48 may set a first gain G1 that is larger when the vehicle speed Vv is high than when it is low, and multiply the speed deviation ΔV by the first gain G1 to calculate the reaction force correction value Cr.
This improves driving stability when driving at high speeds.

(2) The gain multiplication unit 48 may set the first gain G1 to be larger when the vehicle's lateral acceleration Gy is large than when it is small, and may multiply the speed deviation ΔV by the first gain G1 to calculate the reaction force correction value Cr.
This improves driving stability when a large lateral acceleration Gy is occurring.

(3) The gain multiplication unit 51 may set the second gain G2 to be smaller when the vehicle speed Vv is high than when it is low, and may multiply the speed deviation ΔV by the second gain G2 to calculate the steering angle correction value Ct.
Due to the characteristics of the tire rubber of the steered wheels 34, the higher the vehicle speed Vv, the smaller the fluctuation in lateral force immediately after the start of steering becomes.

If the rise of the target steering angle θtr is delayed by the steering angle correction value Ct, when the vehicle speed Vv is high, the rise of the actual yaw rate γa will be delayed, and the vehicle behavior may be felt as sluggish.
By setting the second gain G2 smaller when the vehicle speed Vv is high than when the vehicle speed Vv is low, it is possible to prevent the vehicle behavior from feeling sluggish when the vehicle speed Vv is high.

(4) The gain multiplication unit 51 may set the second gain G2 to be smaller when the vehicle's lateral acceleration Gy is large than when it is small, and may multiply the speed deviation ΔV by the second gain G2 to calculate the steering angle correction value Ct.
In a situation where a high lateral acceleration Gy is occurring, if the rising of the target steering angle θtr is delayed due to the steering angle correction value Ct, causing a delay in the vehicle behavior, the steering feeling may deteriorate.
Therefore, by setting the second gain G2 smaller when the lateral acceleration Gy is large than when it is small, it is possible to prevent the steering feeling from deteriorating in a situation where a high lateral acceleration Gy is occurring.

11...controller, 16...vehicle speed sensor, 17...yaw rate sensor, 18...acceleration sensor, 20...processor, 21...storage device, 22...drive circuit, 31...steering unit, 31a...steering wheel, 31b...column shaft, 31c...reaction force actuator, 31e...steering angle sensor, 31f...current sensor, 32...steered unit, 32a...pinion shaft, 32b...steering gear, 32c...rack gear, 32d...steering rack, 32e...steering actuator, 32g...Steering angle sensor, 32h...Current sensor, 33...Backup clutch, 34...Steering wheels, 34FL, 34FR...Left and right front wheels, 40...Target steering angle calculation unit, 41...Subtractor, 42...Steering angle servo control unit, 43...Steering motor drive unit, 44...Reaction force command value calculation unit, 45...Target yaw angular acceleration calculation unit, 45a...Side force determination unit, 45b...Target yaw rate calculation unit, 45c, 46...Differentiator, 47, 52...Subtractor, 48, 51...Gain multiplication unit, 49...Adder, 50...Reaction force motor drive unit

Claims (7)

A method of steering a vehicle, comprising:
Detects the steering angle of the steering wheel,
Calculating a target steering angle of the steered wheels in accordance with the detected steering angle;
Detecting an actual steering angle, which is an actual steering angle of the steered wheels;
The steered wheels are steered so that the actual steering angle and the target steering angle coincide with each other.
calculating a first reaction force command value which is a command value of a steering reaction force to be applied to the steering wheel, based on the actual turning angle, the target turning angle, or the steering angle;
Detecting an actual yaw rate, which is an actual yaw rate of the vehicle;
calculating a rate of change of a target yaw rate of the vehicle in response to a change in the first reaction force command value;
Calculating a speed deviation which is a difference between a speed of change of the actual yaw rate and a speed of change of the target yaw rate;
calculating a second reaction force command value by adding a reaction force correction value corresponding to the speed deviation to the first reaction force command value;
applying a steering reaction force corresponding to the second reaction force command value to the steering wheel;
A steering method comprising: a first gain is set to be larger when the vehicle speed is high than when the vehicle speed is low;
multiplying the speed deviation by the first gain to calculate the reaction force correction value;
2. The steering method according to claim 1 . a first gain is set to be larger when the lateral acceleration of the vehicle is large than when the lateral acceleration is small;
multiplying the speed deviation by the first gain to calculate the reaction force correction value;
2. The steering method according to claim 1 . Calculating a first target steering angle in accordance with the detected steering angle;
A second target steering angle is calculated as the target steering angle by subtracting a steering angle correction value corresponding to the speed deviation from the first target steering angle.
4. A steering method according to claim 1, wherein the steering wheel is rotated in a direction perpendicular to the axis of the steering wheel. a second gain is set to be smaller when the vehicle speed is high than when the vehicle speed is low;
multiplying the speed deviation by the second gain to calculate the steering angle correction value;
5. The steering method according to claim 4. setting a second gain that is smaller when the lateral acceleration of the vehicle is large than when the lateral acceleration is small;
multiplying the speed deviation by the second gain to calculate the steering angle correction value;
5. The steering method according to claim 4. A steering device for a vehicle, comprising:
A steering angle sensor for detecting a steering angle of a steering wheel;
A steering angle sensor for detecting an actual steering angle, which is an actual steering angle of a steered wheel;
A yaw rate sensor for detecting an actual yaw rate of the vehicle;
a steering actuator that generates a steering force for steering the steered wheels;
a reaction force actuator that generates a steering reaction force to be applied to the steering wheel;
a controller that calculates a target steering angle of the steered wheels in response to the detected steering angle, controls the steering actuator so that the actual steering angle and the target steering angle coincide with each other, calculates a first reaction force command value which is a command value of the steering reaction force based on the actual steering angle, the target steering angle or the steering angle, calculates a rate of change of a target yaw rate of the vehicle in response to a change in the first reaction force command value, calculates a speed deviation which is a difference between the rate of change of the actual yaw rate and the rate of change of the target yaw rate, calculates a second reaction force command value by adding a reaction force correction value in response to the speed deviation to the first reaction force command value, and controls the reaction force actuator to apply a steering reaction force in response to the second reaction force command value to the steering wheel;
A steering device comprising:

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