JP7512831B2 - Steering method and steering device - Google Patents

Description

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

Patent Document 1 describes a steering angle control device that includes a steering member for steering the vehicle and a steering device for steering the wheels, calculates a steering angle according to the steering angle, and controls a steering actuator based on the calculated steering angle. It also describes changing the ratio of the steering angle to the steering angle.

JP 2019-43391 A

If a target steering angle is set according to the steering angle of the steering wheel steered by the driver, and a steering force is generated based on the difference between the actual steering angle of the steered wheels and the target steering angle, the response of the vehicle behavior to the steering operation of the driver becomes faster, which may cause the driver to feel uncomfortable. This tendency becomes more noticeable when the ratio of the steering angle to the steering angle is large.
The present invention aims to reduce the discomfort felt by the driver due to the rapid response of vehicle behavior to steering operations when the ratio of the turning angle to the steering angle is large in a steering device that turns steered wheels with a steering force based on the difference between an actual turning angle and a target turning angle.

In one aspect of the present invention, a steering method for steering the steered wheels of a vehicle detects the steering angle of the steering wheel, detects the actual steering angle of the steered wheels, calculates a target steering angle of the steered wheels according to the detected steering angle, calculates a steering force command value for matching the actual steering angle to the target steering angle based on the difference between the actual steering angle and the target steering angle, delays the phase of the steering force command value with respect to the detected steering angle when the angle ratio, which is the ratio of the target steering angle to the detected steering angle, is larger than when the angle ratio is small, and generates a steering force for turning the steered wheels according to the phase-delayed steering force command value.

According to the present invention, in a steering device that steers steered wheels with a steering force based on the difference between the actual steering angle and the target steering angle, when the ratio of the steering angle to the steering angle is large, it is possible to reduce the discomfort felt by the driver due to the fast response of the vehicle behavior to the steering operation.

1 is a schematic configuration diagram of an example of a steering device according to an embodiment; FIG. 1B is a block diagram of an example of a functional configuration of a controller shown in FIG. 1A. FIG. 4 is a schematic diagram showing an example of a change in steering angle over time. FIG. 2B is a schematic diagram of a steering angle according to the steering angle of FIG. 2A. FIG. 2C is a schematic diagram of a steering force for causing the steering angle change of FIG. 2B. FIG. 2C is a schematic diagram of a self-aligning torque (SAT) generated by the change in the steering angle of FIG. 2B. FIG. 2C is a schematic diagram of a yaw rate caused by the change in steering angle of FIG. 2B. FIG. 2B is a schematic diagram of a steering angle when the phase is delayed with respect to the steering angle of FIG. 2A. FIG. 3B is a schematic diagram of a steering force for causing the steering angle change of FIG. 3A. FIG. 3B is a schematic diagram of the SAT caused by the change in steering angle in FIG. 3A . FIG. 3B is a schematic diagram of a yaw rate caused by the change in steering angle of FIG. 3A. FIG. 4 is a schematic diagram showing an example of a change in steering angle over time. 5 is a schematic diagram of a target turning angle when the angle ratio of the target turning angle to the steering angle is large and small. FIG. FIG. 4C is a schematic diagram showing a case where the phase of the target steering angle in FIG. 4B is delayed. FIG. 2 is a block diagram showing an example of a functional configuration of a steering control unit of the first embodiment. FIG. 11 is an explanatory diagram of a first example of a delay control parameter Kd. FIG. 11 is an explanatory diagram of a second example of the delay control parameter Kd. 4 is a flowchart of an example of a steering method according to the first embodiment. FIG. 11 is a block diagram illustrating an example of a functional configuration of a delay unit according to a second embodiment. FIG. 13 is an explanatory diagram of a third example of the delay control parameter Kd. FIG. 7B is a diagram illustrating an example of a limit value of the limiter in FIG. 7A. FIG. 13 is a block diagram illustrating an example of a functional configuration of a modification of a delay unit according to the second embodiment. FIG. 13 is a block diagram showing an example of a functional configuration of a steering control unit according to a third embodiment. 9B is an explanatory diagram of an example of a gain G set by the gain setting unit of FIG. 9A. FIG. 13 is a block diagram showing an example of a functional configuration of a modified example of the steering control unit of the third embodiment. 10B is an explanatory diagram of an example of a gain G set by the gain setting unit of FIG. 10A. FIG. 13 is a block diagram showing an example of a functional configuration of a modified example of the steering control unit of the third embodiment. FIG. 11B is an explanatory diagram of an example of a gain G set by the gain setting unit of FIG. 11A. FIG. 13 is a block diagram showing an example of a functional configuration of a modified example of the steering control unit of the third embodiment. 12B is an explanatory diagram of an example of a gain G set by the gain setting unit of FIG. 12A. FIG. 13 is a block diagram showing an example of a functional configuration of a modified example of the steering control unit of the third embodiment. 13B is an explanatory diagram of an example of a gain G set by the gain setting unit of FIG. 13A. FIG. 13 is a block diagram showing an example of a functional configuration of a steering control unit according to a fourth embodiment. 13 is a flowchart of an example of a steering method according to the fourth embodiment. FIG. 13 is a block diagram showing an example of a functional configuration of a modified example of the steering control unit of the fourth embodiment. FIG. 13 is a block diagram showing an example of a functional configuration of a steering control unit according to a fifth embodiment. FIG. 17B is an explanatory diagram of an example of a target steering angle set by the steering angle setting unit of FIG. 17A.

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)
1A is a schematic diagram of an example of a vehicle steering device according to the first to fifth embodiments. The steering device according to the embodiment includes a steering unit 31 that receives a steering input from a 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 31 a , a column shaft 31 b , a reaction force actuator 12 , a first drive circuit 13 , a torque sensor 16 , and a steering angle sensor 19 .
On the other hand, the steering unit 32 includes a pinion shaft 32 a, a steering gear 32 b, a rack gear 32 c, a steering rack 32 d, a steering actuator 14, a second drive circuit 15, and a steering angle sensor 35.

The steering wheel 31a of the steering unit 31 is applied with a reaction torque by the reaction actuator 12 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.

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 in a released state under normal circumstances, such as when the vehicle is running or the ignition switch is on, and is in an engaged state when some abnormality occurs in the system, such as an abnormality in the steering actuator 14 or the reaction force actuator 12, or when the ignition switch of the vehicle is off (for example, when the vehicle is 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 steered unit 32 are mechanically separated.

The torque sensor 16 detects the steering torque Ts transmitted from the steering wheel 31a to the column shaft 31b.
The vehicle speed sensor 17 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 steering angle sensor 19 detects the column shaft rotation angle, that is, the steering angle θs (handle angle) of the steering wheel 31a.
The steering angle sensor 35 detects an actual steering angle θt, which is the actual steering angle of the steered wheels 34 .

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, "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 12. The controller 11 includes a processor 20 and peripheral components such as a storage device 21. 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 controller 11 may be realized by a functional logic circuit set 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).

1B is a block diagram showing an example of a functional configuration of the controller 11. The controller 11 includes a reaction force control unit 40 and a steering control unit 41. The functions of the reaction force control unit 40 and the steering control unit 41 may be realized by, for example, the processor 20 executing a computer program stored in the storage device 21 of the controller 11.
The reaction force control unit 40 calculates a reaction force command value fs, which is a command value for the steering reaction force torque (which is a rotational torque applied to the steering wheel 31a, hereinafter also referred to as reaction force torque) to be applied to the steering wheel, in accordance with the steering angle θs detected by the steering angle sensor 19.

The reaction force control unit 40 outputs the reaction force command value fs to the first drive circuit 13. The first drive circuit 13 drives the reaction force actuator 12 based on the reaction force command value fs.
The reaction force actuator 12 may be, for example, an electric motor. The reaction force actuator 12 has an output shaft that is arranged coaxially with the column shaft 31b.
The reaction force actuator 12 outputs a rotational torque to be applied to the steering wheel 31a to the column shaft 31b in response to a command current output from the first drive circuit 13. By applying the rotational torque, a steering reaction force torque is generated in the steering wheel 31a.

The first drive circuit 13 controls the command current output to the reaction force actuator 12 by torque feedback that matches the actual steering reaction force torque estimated from the drive current of the reaction force actuator 12 with the reaction force torque indicated by the reaction force command value fs output from the reaction force control unit 40. Alternatively, the command current output to the reaction force actuator 12 may be controlled by current feedback that matches the drive current of the reaction force actuator 12 with the drive current corresponding to the reaction force command value fs.

The steering control unit 41 calculates a steering force command value ft, which is a command value for the steering force torque for turning the steered wheels 34, based on the steering angle θs of the steering wheel 31a, the actual steering angle θt of the steered wheels 34, and the vehicle speed Vv of the vehicle.
Specifically, the steering control unit 41 calculates a target steering angle θtr, which is a target value of the steering angle of the steered wheels 34, based on the steering angle θs.

The steering control unit 41 may change the angle ratio Ra = θtr/θs, which is the ratio of the target steering angle θtr to the steering angle θs, at least in accordance with the vehicle speed Vv. For example, when the vehicle speed Vv is low, the angle ratio Ra may be set to a relatively large value to improve the maneuverability of the steering wheel 31a, and when the vehicle speed Vv is high, the angle ratio Ra may be set to a relatively small value to improve the handling stability.

The steering control unit 41 calculates a steering force command value ft for making the actual steering angle θt coincide with the target steering angle θtr based on the difference (θtr-θt) between the actual steering angle θt and the target steering angle θtr. The steering force command value ft is calculated to be larger as the difference (θtr-θt) between the actual steering angle θt and the target steering angle θtr becomes larger. The steering force command value ft 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 ft 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 ft may be calculated by referring to the steering force map based on the calculated (θtr-θt).
The steering control section 41 outputs the steering force command value ft to the second drive circuit 15. The second drive circuit 15 drives the steering actuator 14 based on the steering force command value ft.
The steering actuator 14 may be an electric motor such as a brushless motor, etc. An output shaft of the steering actuator 14 is connected to the rack gear 32c via a reducer.

The steering actuator 14 outputs a steering torque for steering the steered wheels 34 to the steering rack 32 d in response to a command current output from the second drive circuit 15 .
Second drive circuit 15 controls the command current output to steering actuator 14 by torque feedback that matches the actual steering torque estimated from the drive current of steering actuator 14 with the steering torque indicated by steering force command value ft output from steering control section 41. Alternatively, the command current output to steering actuator 14 may be controlled by current feedback that matches the drive current of steering actuator 14 with the drive current equivalent to steering force command value ft.

In this way, if a steering force is generated to make the actual steering angle θt coincide with the target steering angle θtr based on the difference (θtr-θt) between the actual steering angle θt and the target steering angle θtr, the response of the vehicle behavior to the driver's steering operation becomes faster, which may cause the driver to feel uncomfortable. The reason for this will be explained with reference to Figures 2A to 2E.

2A is a schematic diagram of the steering angle θs that changes due to the driver's steering operation, FIG. 2B is a schematic diagram of the turning angle θt corresponding to the steering angle θs of FIG. 2A, FIG. 2C is a schematic diagram of the steering force for causing the turning angle change of FIG. 2B, FIG. 2D is a schematic diagram of the self-aligning torque (SAT) caused by the turning angle change of FIG. 2B, and FIG. 2E is a schematic diagram of the yaw rate caused by the turning angle change 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 phase lag of the 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 (Figures 2A and 2B).

Immediately after the steering angle θt starts to change, there is a large angular difference between the orientation of the steered wheels 34 and the traveling direction of the steered wheels 34. For this reason, if the actual steering angle θt follows the target steering angle θtr with little delay, the lateral force generated in the tires increases sharply.
For this reason, immediately after the turning angle θt starts to change, the turning force and the self-aligning torque increase rapidly as shown in FIGS. 2C and 2D.
As a result, as shown in FIG. 2E, the yaw rate increases rapidly immediately after the steering angle θt starts to change, and the vehicle behavior becomes faster in response to the steering force applied to the steering wheel 31a by the driver, which may cause the driver to feel uncomfortable.

Therefore, the steering control unit 41 of the embodiment delays the phase of the steering force command value ft with respect to the steering angle θs. This makes it possible to delay the steering angle θt with respect to the steering angle θs immediately after the steering angle θt starts to change, as shown by the solid line in Fig. 3A.
The solid lines in Figures 3A to 3D are schematic diagrams of the steering angle θt, the steering force, the SAT, and the yaw rate when the phase of the steering force command value ft is delayed with respect to the steering angle θs shown in Figure 2A. For comparison, the case where the phase is not delayed is shown by the dashed line.
As shown in Fig. 3A, by delaying the phase of the steering force command value ft, the steering angle θt is delayed, which makes it possible to make the changes in the steering force, SAT, and yaw rate gentler. This makes it possible to prevent the vehicle behavior from becoming faster in response to the steering force applied by the driver, thereby reducing the sense of discomfort felt by the driver.

As described above, the steering control unit 41 can change the angle ratio (Ra=θtr/θs) of the target steering angle θtr to the steering angle θs. If the angle ratio Ra becomes large, the above-mentioned effect achieved by delaying the phase of the steering force command value ft is impaired.
FIG. 4A is a schematic diagram of the steering angle θs that changes due to the driver's steering operation, and the dashed dotted line 42 in FIG. 4B represents the steering angle θt when the angle ratio Ra is relatively small, while the solid line 43 in FIG. 4B represents the steering angle θt when the angle ratio Ra is relatively large.
As shown in the figure, the steering angle θt (solid line) when the angle ratio Ra is relatively large changes faster than the steering angle θt (dotted line) when the angle ratio Ra is relatively small.

When the phase of the steering force command value ft is delayed, the steering angles θt become as shown by two-dot chain line 44 and solid line 45 in Fig. 4C. For comparison, the steering angle θt when the angle ratio Ra is relatively small and the phase is not delayed is shown by one-dot chain line 42.
From FIG. 4C, it can be seen that the rate of change of the steering angle θt when the angle ratio Ra is relatively large and the phase is delayed is the same as the rate of change of the steering angle when the angle ratio Ra is relatively small and the phase is not delayed.
For this reason, even if the phase is uniformly delayed, if the angle ratio Ra becomes large, the vehicle behavior immediately after the steering angle θt starts to change becomes fast, which may cause the driver to feel uncomfortable.

Therefore, the steering control section 41 delays the phase of the steering force command value ft with respect to the steering angle θs when the angle ratio Ra is large compared to when the angle ratio Ra is small.
For example, when the angle ratio Ra is equal to or greater than a predetermined threshold, the phase of the steering force command value ft is delayed, and when the angle ratio Ra is less than the predetermined threshold, the phase of the steering force command value ft is not delayed. Also, for example, when the angle ratio Ra is large, the amount of delay in the phase of the steering force command value ft relative to the steering angle θs is made larger than when the angle ratio Ra is small.
This makes it possible to reduce the discomfort felt by the driver due to the fast response of the vehicle behavior to the steering operation when the angle ratio Ra is large.

The steering control unit 41 will be described in further detail below.
5A is a block diagram showing an example of the functional configuration of the steering control unit 41 of the first embodiment. The steering control unit 41 includes a steering angle setting unit 50, a delay amount setting unit 51, a delay unit 52, and a steering angle control unit 53.
The steering angle setting unit 50 calculates the target steering angle θtr according to the steering angle θs. For example, the steering angle setting unit 50 calculates the target steering angle θtr by multiplying the steering angle θs by the angle ratio Ra. The angle ratio Ra is an example of a "gain" as defined in the claims.

The steering angle setting unit 50 may dynamically change the angle ratio Ra. For example, the steering angle setting unit 50 may change the angle ratio Ra in accordance with at least the vehicle speed Vv.
For example, when the vehicle speed Vv is low, the angle ratio Ra may be set to a relatively large value to improve maneuverability of the steering wheel 31a, and when the vehicle speed Vv is high, the angle ratio Ra may be set to a relatively small value to improve handling stability.

The steering angle setting section 50 outputs the target steering angle θtr to a delay section 52 , and outputs the angle ratio Ra to a delay amount setting section 51 .
The delay amount setting unit 51 sets a delay control parameter Kd, which determines the amount of delay by the delay unit 52 , in accordance with the angle ratio Ra, and outputs the parameter Kd to the delay unit 52 .
The delay unit 52 delays (delays) the phase of the target steering angle θtr output by the steering angle setting unit 50 by a delay amount determined by the delay control parameter Kd. The delay unit 52 outputs the target steering angle θtrd with the phase delayed to the steering angle control unit 53.

The steering angle control unit 53 calculates a steering force command value ft for making the actual steering angle θt coincide with the target steering angle θtrd, based on the difference between the phase-delayed target steering angle θtrd and the actual steering angle θt.
In this way, delay section (delay means) 52 delays the phase of target steering angle θtr, thereby delaying the phase of steering force command value ft calculated by steering angle control section 53 with respect to steering angle θs.
The delay control parameter Kd can be any of various values that determine the amount of delay by the delay unit 52. For example, the delay control parameter Kd may be the amount of delay itself.

Fig. 5B is an explanatory diagram of a first example of the delay control parameter Kd when a delay amount is adopted. The delay control parameter Kd in Fig. 5B increases as the angle ratio Ra increases. Therefore, the phase delay of the steering force command value ft increases as the angle ratio Ra increases.
The delay control parameter Kd may increase nonlinearly or linearly as shown in Fig. 5B. Also, as shown in Fig. 5B, the delay control parameter Kd may have a characteristic in which the rate of change of the delay control parameter Kd increases as the angle ratio Ra decreases (i.e., an upwardly convex characteristic).

Figure 5C is an explanatory diagram of a second example of the delay control parameter Kd when a delay amount is adopted. The delay control parameter Kd in Figure 5C is 0 when the angle ratio Ra is less than the threshold value Ra1, and is a non-zero value Kd1 when the angle ratio Ra is equal to or greater than the threshold value Ra1. Therefore, when the angle ratio Ra is equal to or greater than the threshold value Ra1, the phase of the steering force command value ft is delayed, and when the angle ratio Ra is less than the threshold value Ra1, the phase of the steering force command value ft is not delayed.

The delay section 52 may be, for example, a phase delay filter (delay filter) that delays the phase of the input signal by an amount of delay determined by a delay control parameter Kd.
In addition, the delay unit 52 may delay the phase of the target turning angle θtr by outputting a signal obtained by adding the integral term of the target turning angle θtr to the proportional term of the target turning angle θtr, as in a second embodiment described later.

(motion)
Next, an example of a steering method according to the first embodiment will be described with reference to FIG.
In step S1, the steering angle sensor 19 detects the steering angle θs of the steering wheel 31a.
In step S2, the steering angle sensor 35 detects the actual steering angle θt of the steered wheels 34.
In step S3, the steering angle setting unit 50 calculates the target steering angle θtr in accordance with the steering angle θs.

In step S4, the delay amount setting unit 51 calculates a delay control parameter Kd in accordance with the angle ratio Ra of the target turning angle θtr to the steering angle θs.
In step S5, the delay section 52 delays the phase of the target steering angle θtr output by the steering angle setting section 50 by an amount of delay determined by the delay control parameter Kd.
In step S6, the steering angle control unit 53 calculates the steering force command value ft based on the difference between the phase-delayed target steering angle θtrd and the actual steering angle θt.
In step S7, the second drive circuit 15 drives the steering actuator 14 based on the steering force command value ft.

(Effects of the First Embodiment)
(1) Steering angle sensor 19 detects steering angle θs of steering wheel 31a. Steering angle sensor 35 detects actual steering angle θt of steered wheels 34. Steering angle setting unit 50 calculates target steering angle θtr in accordance with steering angle θs. Delay unit 52 delays the phase of target steering angle θtr when angle ratio Ra, which is the ratio of target steering angle θtr to steering angle θs, is large compared to when angle ratio Ra is small.

Based on the difference between the phase-delayed target steering angle θtrd and the actual steering angle θt, steering angle control section 53 calculates steering force command value ft for making the actual steering angle θt coincide with the target steering angle θtrd. Therefore, when the angle ratio Ra is large, the phase of the steering force command value ft lags behind the steering angle θs more when the angle ratio Ra is small. Second drive circuit 15 and steering actuator 14 generate a steering force for steering steered wheels 34 in accordance with the phase-delayed steering force command value ft.
This makes it possible to reduce the discomfort felt by the driver due to the quick response of the vehicle behavior to the steering operation when the angle ratio Ra is large.

(2) The steering angle setting unit 50 may calculate the target steering angle θtr by multiplying the steering angle θs by the angle ratio Ra. The delay unit 52 may delay the phase of the steering force command value ft with respect to the steering angle θs as the angle ratio Ra increases.
This makes it possible to suppress the response of the vehicle behavior to the steering operation from becoming faster as the angle ratio Ra increases.

(3) The steering angle setting unit 50 may dynamically set the angle ratio Ra in accordance with at least the vehicle speed Vv. The delay unit 52 may delay the phase of the steering force command value ft with respect to the steering angle θs as the dynamically varying angle ratio Ra increases.
This makes it possible to suppress the response of the vehicle behavior to the steering operation from becoming faster as the angle ratio Ra dynamically increases.

(4) The phase of the steering force command value ft may be delayed with respect to the steering angle θs by delaying the phase of the target steering angle θtr calculated according to the steering angle θs. This makes it possible to suppress an increase in the response of the vehicle behavior to the steering force applied by the driver, thereby reducing the discomfort felt by the driver.
(5) The delay unit 52 may be a delay filter. This makes it possible to delay the phase of the steering force command value ft with respect to the steering angle θs.

Second Embodiment
The second embodiment presents an example of delay section 52 of steering control section 41. Delay section 52 of the second embodiment delays the phase of target steering angle θtr by adding an integral term of target steering angle θtr set by steering angle setting section 50 to a proportional term of target steering angle θtr.
7A, the delay section 52 includes a gain multiplication section 60, a delay element 61, adders 62 and 64, and a limiter 63.

The target steering angle θtr set by the steering angle setting unit 50 is allocated to K×θtr and (1-K)×θtr by a distribution coefficient K: (1-K). Here, K is a coefficient greater than 0 and less than 1, and may be, for example, K=0.5. In this case, the target steering angle θtr is divided equally. The distribution coefficient K may be a value other than 0.5, and may be set appropriately depending on the desired magnitude of delay.

The steering angle setting unit 50 may distribute the target steering angle θtr between K×θtr and (1-K)×θtr by multiplying the target steering angle θtr by a distribution coefficient K: (1-K). Alternatively, for example, the steering angle setting unit 50 may output the target steering angle θtr to the delay unit 52, which may multiply the target steering angle θtr by gains K and (1-K) to distribute it between K×θtr and (1-K)×θtr. Hereinafter, K×θtr and (1-K)×θtr are referred to as "distributed target steering angles".

The gain multiplication unit 60 multiplies the distribution target turning angle (1-K) x θtr by the integral gain Ki determined by the delay control parameter Kd. As described above, the delay control parameter Kd is set in accordance with the angle ratio Ra.
Gain multiplication section 60 reduces integral gain Ki so that the amount of delay increases as angle ratio Ra increases, so that the phase delay of steering force command value ft increases as angle ratio Ra increases.

An integral gain Ki may be adopted as the delay control parameter Kd. Fig. 7B is an explanatory diagram of an example of the delay control parameter Kd indicating the integral gain Ki.
7B (i.e., integral gain Ki) becomes smaller as the angle ratio Ra increases, so that the phase delay of the steering force command value ft becomes larger.
The delay control parameter Kd may decrease nonlinearly or linearly as shown in Fig. 7B. Also, as shown in Fig. 7B, the delay control parameter Kd may have a characteristic in which the rate of change of the delay control parameter Kd increases as the angle ratio Ra decreases (i.e., a downwardly convex characteristic).

7A, the delay element 61 holds the past value of the integral of the output (Ki×(1−K)×θtr) of the gain multiplication unit.
The adder 62 integrates the output (Ki×(1−K)×θtr) of the gain multiplication section 60 by adding the output (Ki×(1−K)×θtr) to the past integrated value.
Here, the coefficient Ki×(1−K) can also be regarded as an integral gain. Therefore, the integral value of the output (Ki×(1−K)×θtr) integrated by the adder 62 can be regarded as an integral term of the target steering angle θtr.

The limiter 63 limits the magnitude (ie, absolute value) of the integral term of the target turning angle θtr to a limit value or less.
For example, the limiter 63 may limit the magnitude (ie, absolute value) of the integral term of the target turning angle θtr to a limit value or less, using a limit value that changes depending on the target turning angle θtr.
See Fig. 7C. The larger the target turning angle θtr, the larger the limit value. As with the target turning angle θtr, the limit value may be changed according to the vehicle speed Vv.

This prevents the integral term of the target steering angle θtr from continuing to increase even if the target steering angle θtr is maintained at a non-zero angle in a steering state, and fixes the output of the delay section 52 (i.e., the target steering angle θtrd with a phase delay) to an angle corresponding to the target steering angle θtr.
7A, adder 64 adds the integral term of target turning angle θtr output from limiter 63 to distribution target turning angle K×θtr (i.e., the proportional term of target turning angle θtr) to calculate target turning angle θtrd with a delayed phase.

8 is a block diagram of an example of a functional configuration of a modified example of delay unit 52 of the second embodiment. Delay unit 52 of the modified example includes a subtractor 65. Subtractor 65 inputs to gain multiplication unit 60 a difference obtained by subtracting a past value of the integrated value of the output (Ki×(1−K)×θtr) of gain multiplication unit 60 from the distribution target turning angle (1−K)×θtr.
Therefore, when the target steering angle θtr becomes constant (i.e., there is no change over time) and the distribution target steering angle (1-K)×θtr becomes equal to the integral value of the output of gain multiplication unit 60 (Ki×(1-K)×θtr), the input to gain multiplication unit 60 is canceled and the integral value no longer changes.

Therefore, the gain multiplication section 60, the delay element 61, the adder 62 and the subtractor 65 calculate an integral term of only the fluctuation component of the target turning angle θtr.
This prevents the integral term of the target steering angle θtr from continuing to increase even if the target steering angle θtr is maintained at a non-zero angle in a steering state, and fixes the output of the delay section 52 (i.e., the target steering angle θtrd with a phase delay) to an angle corresponding to the target steering angle θtr.

(Effects of the Second Embodiment)
(1) The delay unit 52 may delay the phase of the target turning angle θtr by adding an integral term of the target turning angle θtr calculated according to the steering angle θs to a proportional term of the target turning angle θtr. This makes it possible to delay the phase of the turning force command value ft with respect to the steering angle θs.
(2) Delay unit 52 may add an integral term calculated by integrating only the fluctuation component of target turning angle θtr to the proportional term of target turning angle θtr, or may limit the integral term of target turning angle θtr by a limit value corresponding to target turning angle θtr and then add it to the proportional term of target turning angle θtr. This makes it possible to prevent the integral term of target turning angle θtr from continuing to increase even if target turning angle θtr is maintained at an angle other than zero in a steering state, and fix the output of delay unit 52 (i.e., target turning angle θtrd with a delayed phase) to an angle corresponding to target turning angle θtr.

Third Embodiment
As described above, the response of the vehicle behavior to the steering operation becomes faster immediately after the actual steering angle θt starts to change. Therefore, it is preferable to delay the phase of the steering force command value ft with respect to the steering angle θs during the period immediately after the actual steering angle θt starts to change, and not to delay the phase during other periods.
Therefore, the steering control unit 41 of the third embodiment delays the phase of the steering force command value ft relative to the steering angle θs when the steering angle θs is less than a predetermined value, and does not delay the phase of the steering force command value ft relative to the steering angle θs when the steering angle θs is greater than or equal to the predetermined value.

Figure 9A is a block diagram of an example of the functional configuration of the steering control unit 41 of the third embodiment. The steering control unit 41 of the third embodiment further includes a gain setting unit 70, multipliers 71 and 73, a subtractor 72, and an adder 74. The delay unit 52 may be a phase delay filter (delay filter) or may be the delay unit 52 of the second embodiment.

The gain setting unit 70 sets a gain G according to the steering angle θs. The gain G is a gain that is not zero when the steering angle θs is less than a predetermined value, and is zero when the steering angle θs is equal to or greater than the predetermined value.
For example, gain setting unit 70 may set gain G according to target turning angle θtr that is set based on steering angle θs. As described above, target turning angle θtr is the product of steering angle θs and angle ratio Ra.

9B is a diagram illustrating an example of gain G. The value of gain G is "1" when the target steering angle θtr is θ1 or less, "0" when the target steering angle θtr is θ2 or more, and decreases from "1" to "0" as the target steering angle θtr increases when the target steering angle θtr is greater than θ1 and less than θ2.
Multipliers 71 and 73, subtractor 72 and adder 74 calculate a weighted sum (G×θtrd+(1−G)×θtr) of target turning angle θtrd whose phase has been delayed by delay section 52 and target turning angle θtr.

The steering angle control unit 53 calculates a steering force command value ft for matching the actual steering angle θt to the weighted sum (G×θtrd+(1−G)×θtr) based on the difference between the weighted sum (G×θtrd+(1−G)×θtr) and the actual steering angle θt.
Therefore, when the target steering angle θtr is equal to or larger than θ2, the weighted sum (G×θtrd+(1−G)×θtr) becomes the target steering angle θtr, and there is no phase delay. Therefore, no phase delay occurs in the steering force command value ft relative to the steering angle θs.

On the other hand, when the target steering angle θtr is less than θ2, the weighted sum (G×θtrd+(1−G)×θtr) includes a component of the target steering angle θtrd with a phase delay, so that the phase lag occurs with respect to the steering angle θs. As a result, a phase delay occurs in the steering force command value ft with respect to the steering angle θs.
This allows the steering force command value ft to be generated so that the phase of the steering force command value ft is delayed with respect to the steering angle θs in the period immediately after the steering angle θs starts to change from the neutral position, and so that the phase is not delayed in other periods.

FIG. 10A is a block diagram showing an example of a functional configuration of a first modified example of the steering control unit 41 of the third embodiment.
The steering control unit 41 of the first variant delays the phase of the steering force command value ft relative to the steering angle θs when the angular velocity of the steering angle θs is less than a predetermined value, and does not delay the phase of the steering force command value ft relative to the steering angle θs when the angular velocity of the steering angle θs is greater than or equal to the predetermined value.
This makes it possible to lag the phase of the steering force command value ft with respect to the steering angle θs not only immediately after the steering angle θs starts to change from the neutral position, but also immediately after the steering angle θs starts to change from a state in which it is held at a position other than the neutral position.

The gain setting unit 70 sets the gain G according to the angular velocity of the steering angle θs. For example, the gain setting unit 70 may set the gain G to be non-zero when the angular velocity of the steering angle θs is less than a predetermined value, and to be zero when the angular velocity of the steering angle θs is equal to or greater than the predetermined value.
For example, the gain setting unit 70 may set the gain G in accordance with the steering angular velocity ω obtained by differentiating the target steering angle θtr.

The steering control section 41 of the first modified example includes a differentiator 75 that differentiates the target steering angle θtr to calculate the steering angular velocity ω.
The gain setting unit 70 sets a gain G according to the steering angular velocity ω.
10B is a diagram illustrating an example of the gain G. The value of the gain G is "1" when the steering angular velocity ω is equal to or less than ω1, and is "0" when the steering angular velocity ω is equal to or greater than ω2.

When the steering angular velocity ω is greater than ω1 and less than ω2, the value decreases from "1" to "0" as the steering angular velocity ω increases.
Therefore, when the steering angular velocity ω is equal to or greater than ω2, the value of the weighted sum (G×θtrd+(1−G)×θtr) becomes the target steering angle θtr, and there is no phase lag. Therefore, no phase lag occurs in the steering force command value ft relative to the steering angle θs.

On the other hand, when the steering angular velocity ω is less than ω2, the weighted sum (G×θtrd+(1−G)×θtr) includes a component of the target steering angle θtrd with a phase delay, so that the phase lag occurs with respect to the steering angle θs. As a result, a phase lag occurs in the steering force command value ft with respect to the steering angle θs.
This allows the steering force command value ft to be generated so that the phase of the steering force command value ft is delayed relative to the steering angle θs during the period immediately after the steering angle θs begins to change from a stationary state of the steering wheel 31a, and so that the phase is not delayed during the period while the steering angle θs is changing.

FIG. 11A is a block diagram showing an example of a functional configuration of a second modified example of the steering control unit 41 of the third embodiment.
The steering control unit 41 of the above-mentioned first modified example may delay the phase of the steering force command value ft with respect to the steering angle θs during the period from when the steering angle θs is changing to when the steering wheel 31a is stationary and the steering angle θs is held stationary, even if it is not immediately after the steering angle θs starts to change. This is because the angular velocity of the steering angle θs becomes small during the period when the steering wheel 31a is held stationary.

Therefore, the steering control unit 41 of the second modified example delays the phase of the steering force command value ft relative to the steering angle θs when the angular acceleration of the steering angle θs is less than a predetermined value, and does not delay the phase of the steering force command value ft relative to the steering angle θs when the angular acceleration of the steering angle θs is greater than or equal to the predetermined value.
As a result, even if the angular velocity of the steering angle θs decreases during the period when the steering wheel is switched to a held-steer state, the angular acceleration of the steering angle θs is detected and delay in the phase of the steering force command value ft can be suppressed.

The gain setting unit 70 sets the gain G according to the angular acceleration of the steering angle θs. For example, the gain setting unit 70 may set the gain G to be non-zero when the angular acceleration of the steering angle θs is less than a predetermined value, and to be zero when the angular acceleration of the steering angle θs is equal to or greater than the predetermined value.
For example, the gain setting unit 70 may set the gain G in accordance with the turning angular acceleration α obtained by second-order differentiation of the target turning angle θtr.

The steering control section 41 of the first modified example includes a differentiator 76 that calculates the steering angular acceleration α by differentiating the steering angular velocity ω of the target steering angle θtr.
Gain setting unit 70 sets gain G according to steering angular acceleration α. Fig. 11B is a diagram illustrating an example of gain G. The value of gain G is "1" when steering angular acceleration α is equal to or less than α1, and is "0" when steering angular acceleration α is equal to or more than α2.

When the turning angular acceleration α is greater than α1 and less than α2, the value decreases from "1" to "0" as the turning angular acceleration α increases.
Therefore, when the steering angular acceleration α is equal to or greater than α2, the weighted sum (G×θtrd+(1−G)×θtr) becomes the target steering angle θtr, and there is no phase delay. Therefore, no phase delay occurs in the steering force command value ft relative to the steering angle θs.

On the other hand, when the steering angular acceleration α is less than α2, the weighted sum (G×θtrd+(1−G)×θtr) includes a component of the target steering angle θtrd with a delayed phase, so that the phase lag occurs with respect to the steering angle θs. As a result, a phase lag occurs in the steering force command value ft with respect to the steering angle θs.
This allows the phase of the steering force command value ft to be delayed relative to the steering angle θs during the initial period when the steering angle θs starts to change while the angular acceleration is still small immediately after the steering wheel 31a starts to change.
In addition, during the period when the steering angle θs transitions from a state in which the steering angle θs is changing to a stationary steering state in which the steering wheel 31a is stationary, even if the angular velocity of the steering angle θs decreases, the angular acceleration of the steering angle θs can be detected, and delay in the phase of the steering force command value ft can be suppressed.

FIG. 12A is a block diagram showing an example of a functional configuration of a third modified example of the steering control unit 41 of the third embodiment.
The steering control unit 41 of the third modified example delays the phase of the steering force command value ft relative to the steering angle θs when the steering torque Ts applied to the steering wheel 31a is less than a predetermined value, and does not delay the phase of the steering force command value ft relative to the steering angle θs when the steering torque Ts is greater than or equal to the predetermined value.
The steering control unit 41 of the third modified example has the same effects as those of the steering control unit 41 of the second modified example.

The gain setting unit 70 sets the gain G according to the steering torque Ts. FIG. 12B is an explanatory diagram of an example of the gain G. The value of the gain G is "1" when the steering torque Ts is equal to or less than T1, and is "0" when the steering torque Ts is equal to or greater than T2.

When the steering torque Ts is greater than T1 and less than T2, the value decreases from "1" to "0" as the steering torque Ts increases.
Therefore, when the steering torque Ts is equal to or greater than T2, the weighted sum (G×θtrd+(1−G)×θtr) becomes the target steering angle θtr, and there is no phase lag. Therefore, no phase lag occurs in the steering force command value ft relative to the steering angle θs.
On the other hand, when the steering torque Ts is less than T2, the weighted sum (G×θtrd+(1−G)×θtr) includes a component of the target steering angle θtrd with a delayed phase, and therefore the phase lags with respect to the steering angle θs. As a result, a phase lag occurs in the steering force command value ft with respect to the steering angle θs.

FIG. 13A is a block diagram showing an example of a functional configuration of a fourth modified example of the steering control unit 41 of the third embodiment.
The steering control unit 41 of the fourth modified example delays the phase of the steering force command value ft with respect to the steering angle θs when the time change j of the steering torque Ts is less than a predetermined value, and does not delay the phase of the steering force command value ft with respect to the steering angle θs when the time change j of the steering torque Ts is equal to or greater than the predetermined value.
The time change j of the steering torque Ts may be replaced with the steering angle jerk (steering angle jerk, steering angle jerk) of the steering angle θs.

This allows the steering angle θs to start changing from a stationary state of the steering wheel 31a, and during the initial period immediately after the steering angle θs starts to change and when the steering angle jerk is still small, the phase of the steering force command value ft can be delayed with respect to the steering angle θs.
In addition, during the period when the state transitions from one in which the steering angle θs is changing to a held-steering state in which the steering wheel 31a is stationary, the phase of the steering force command value ft can be prevented from being delayed until the point at which the steering angle jerk becomes small just before the transition to the held-steering state.

The steering control section 41 of the first modified example includes a differentiator 75 that differentiates the steering torque Ts to calculate the time change j of the steering torque Ts.
The gain setting unit 70 sets a gain G according to the time change j. Fig. 13B is a diagram illustrating an example of the gain G. The value of the gain G is "1" when the time change j is equal to or less than j1, and is "0" when the time change j is equal to or more than j2.

When the time change j is greater than j1 and less than j2, it decreases from "1" to "0" as the time change j increases.
Therefore, when the time change j is equal to or greater than j2, the weighted sum (G×θtrd+(1−G)×θtr) becomes the target steering angle θtr, and there is no phase lag. Therefore, no phase lag occurs in the steering force command value ft relative to the steering angle θs.
On the other hand, when the time change j is less than j2, the weighted sum (G×θtrd+(1−G)×θtr) includes a component of the target steering angle θtrd with a delayed phase, so that the phase lag occurs with respect to the steering angle θs. As a result, a phase lag occurs in the steering force command value ft with respect to the steering angle θs.

Note that any of the first to fourth modified examples may be combined. For example, when the values of multiple variables of the steering angular velocity, steering angular acceleration, or steering angular jerk of the steering angle θs are each less than a threshold value, the phase of the steering force command value ft may be delayed with respect to the steering angle θs. The steering angular acceleration and steering angular jerk of the steering angle θs may be replaced with the steering torque Ts or the time change j of the steering torque Ts.

(Effects of the Third Embodiment)
The steering control unit 41 delays the phase of the steering force command value ft with respect to the steering angle θs when the steering angle θs, or the steering angular velocity, steering angular acceleration, or steering angular jerk of the steering angle θs, the steering torque Ts applied to the steering wheel 31a, or the time change j of the steering torque Ts is less than a predetermined value.
This makes it possible to lag the phase of the steering force command value ft with respect to the steering angle θs in the period immediately after the steering angle θt starts to change, when the response of the vehicle behavior to the steering operation becomes fast, and to suppress phase lag in other periods.

Fourth Embodiment
The steering control section 41 in the first embodiment described above delays the phase of the target steering angle θtr, thereby delaying the phase of the steering force command value ft with respect to the steering angle θs.
Instead, the steering control section 41 of the fourth embodiment delays the phase of the steering force command value ft relative to the steering angle θs by delaying the phase of the steering force command value output by the steering angle control section 53.
This provides the same effects as those provided by the steering control unit 41 of the first embodiment.

FIG. 14 is a block diagram showing an example of a functional configuration of the steering control unit 41 according to the fourth embodiment.
The steering angle control unit 53 calculates a reference steering force command value ft0 for making the actual steering angle θt coincide with the target steering angle θtr based on the difference between the target steering angle θtr set by the steering angle setting unit 50 and the actual steering angle θt.
Delay unit 52 delays (delays) the phase of reference turning force command value ft0 output by steering angle control unit 53 by an amount of delay determined by delay control parameter Kd, and outputs the result as turning force command value ft. Delay unit 52 may be, for example, a phase delay filter (delay filter).

Next, an example of a steering method according to the fourth embodiment will be described with reference to FIG.
The processes in steps S11 to S14 are similar to those in steps S1 to S4 in FIG.
In step S15, the steering angle control unit 53 calculates a reference steering force command value ft0 for matching the actual steering angle θt to the target steering angle θtr based on the difference between the target steering angle θtr set by the steering angle setting unit 50 and the actual steering angle θt.

In step S16, delay unit 52 delays (delays) the phase of reference steering force command value ft0 output by steering angle control unit 53 by a delay amount determined by delay control parameter Kd, and outputs steering force command value ft with the phase delayed.
The process of step S17 is similar to the process of step S7 in FIG.

FIG. 16 is a block diagram showing an example of a functional configuration of a modified example of the steering control unit 41 of the fourth embodiment.
The steering control unit 41 of the fourth embodiment, like the steering control unit 41 of the third embodiment, delays the phase of the steering force command value ft with respect to the steering angle θs when the steering angle θs is less than a predetermined value, and does not delay the phase of the steering force command value ft with respect to the steering angle θs when the steering angle θs is equal to or greater than the predetermined value.

For this reason, the steering control section 41 of the modified example comprises a gain setting section 70, multipliers 71 and 73, a subtractor 72, and an adder 74, similar to the steering control section 41 of the third embodiment.
The gain setting unit 70 sets a gain G according to the steering angle θs in the same manner as the gain setting unit 70 of the third embodiment. The gain G is a gain that is not zero when the steering angle θs is less than a predetermined value, and is zero when the steering angle θs is equal to or greater than the predetermined value.
Multipliers 71 and 73, subtractor 72 and adder 74 calculate the weighted sum (G × ft1 + (1-G) × ft0) of the reference steering force command value ft0 and the steering force command value ft1, which is obtained by delaying the phase of the reference steering force command value ft0 by delay section 52, as the steering force command value ft.

Therefore, when the steering angle θs is equal to or greater than a predetermined value, the steering force command value ft becomes the reference steering force command value ft0 which does not include a phase delay. Therefore, no phase delay occurs in the steering force command value ft with respect to the steering angle θs.
On the other hand, when the steering angle θs is less than a predetermined value, the weighted sum (G×θtrd+(1−G)×θtr) includes a component of the steering force command value ft1 with a phase delay. Therefore, as in the third embodiment, a phase delay occurs in the steering force command value ft with respect to the steering angle θs.

Furthermore, the gain setting unit 70 of the fourth embodiment may calculate gains according to the steering angular velocity ω, the steering angular acceleration α, the steering torque Ts, and the change in steering torque Ts over time, similar to the gain setting unit 70 of the first to fourth modified examples of the third embodiment.
As a result, the steering control unit 41 of the fourth embodiment does not delay the phase of the steering force command value ft relative to the steering angle θs when the steering angular velocity, steering angular acceleration, or steering angular jerk of the steering angle θs, the steering force Ts applied to the steering wheel 31a, or the change in time j of the steering force Ts are equal to or greater than a predetermined value, but may delay the phase when the steering angular velocity, steering angular acceleration, steering angular jerk, steering force Ts, or the change in time j of the steering force is less than a predetermined value.

(Effects of the Fourth Embodiment)
The steering control unit 41 may delay the phase of the steering force command value ft relative to the steering angle θs by delaying the phase of the steering force command value ft calculated based on the difference between the actual steering angle θt and the target steering angle θtr.
This makes it possible to suppress an increase in the response of the vehicle behavior to the steering force applied by the driver, thereby reducing the sense of discomfort felt by the driver.

Fifth Embodiment
17A is a block diagram of an example of the functional configuration of the steering control unit 41 of the fifth embodiment. The steering angle setting unit 50 in the fifth embodiment changes the angle ratio Ra in accordance with the steering angle θs. That is, the angle ratio Ra is set in accordance with the steering angle θs.
For example, the steering angle setting unit 50 may change the angle ratio Ra in accordance with the vehicle speed Vv and the steering angle θs.

Fig. 17B is an explanatory diagram of an example of target steering angle θtr set by steering angle setting unit 50 in Fig. 17A. As can be seen from target steering angle θtr in Fig. 17B, the larger the steering angle θs, the larger the angle ratio Ra becomes, and the higher the vehicle speed Vv, the smaller the angle ratio Ra becomes.
By setting a larger angle ratio Ra as the steering angle θs increases, the maneuverability of the steering wheel 31a can be improved.

Alternatively, the steering angle setting unit 50 may set a smaller angle ratio Ra as the steering angle θs increases. By setting a smaller angle ratio Ra as the steering angle θs increases, the driving stability can be improved.
The delay amount setting unit 51 includes an angle ratio calculation unit 51a and a coefficient setting unit 51b.
The angle ratio calculation unit 51a calculates the angle ratio Ra by dividing the steering angle θs by the target turning angle θtr.

The coefficient setting unit 51b sets the delay control parameter Kd in accordance with the angle ratio Ra, and outputs the set parameter Kd to the delay unit 52. The method of setting the delay control parameter Kd in accordance with the angle ratio Ra is the same as that described above.
The steering angle setting unit 50 and the delay amount setting unit 51 of the fifth embodiment may be applied to the second to fourth embodiments.

(Effects of the Fifth Embodiment)
The steering angle setting unit 50 may dynamically set the angle ratio Ra in accordance with at least the steering angle θs. The delay unit 52 may delay the phase of the steering force command value ft with respect to the steering angle θs as the dynamically varying angle ratio Ra increases.
This makes it possible to suppress the response of the vehicle behavior to the steering operation from becoming faster as the angle ratio Ra dynamically increases.

11...controller, 12...reaction force actuator, 13...first drive circuit, 14...steering actuator, 15...second drive circuit, 16...torque sensor, 17...vehicle speed sensor, 19...steering angle sensor, 20...processor, 21...storage device, 31...steering section, 31a...steering wheel, 31b...column shaft, 32...steering section, 32a...pinion shaft, 32b...steering gear, 32c...rack gear, 32d...steering rack, 33...backup Clutch, 34...steered wheels, 34FL...left and right front wheels, 34FR...left and right front wheels, 35...steering angle sensor, 40...reaction force control unit, 41...steering control unit, 50...steering angle setting unit, 51...delay amount setting unit, 51a...angle ratio calculation unit, 51b...coefficient setting unit, 52...delay unit (delay means), 53...steering angle control unit, 60...gain multiplication unit, 61...delay element, 62, 64, 74...adder, 63...limiter, 65, 72...subtractor, 70...gain setting unit, 71, 73...multiplier, 75, 76...differentiator

Claims (9)

In a steering device in which a steering unit that receives a steering input from a driver and a steering unit that steers steered wheels of a vehicle are mechanically separated, a steering method for steering the steered wheels includes the steps of:
Detects the steering angle of the steering wheel,
An actual steering angle is detected, which is the actual steering angle of the steered wheels.
A larger angle ratio is set when the vehicle speed is low than when the vehicle speed is high.
multiplying the detected steering angle by the angle ratio to calculate a target steering angle of the steered wheels;
calculating a steering force command value for making the actual steering angle coincide with the target steering angle based on a difference between the actual steering angle and the target steering angle;
delaying a phase of the steering force command value with respect to the detected steering angle by a larger delay amount when the angle ratio, which is a ratio of the target steering angle to the detected steering angle, is large compared to when the angle ratio is small;
generating a steering force for steering the steered wheels in accordance with the steering force command value whose phase is delayed;
A steering method comprising: 2. The steering method according to claim 1 , wherein a phase of the steering force command value is delayed with respect to the detected steering angle by delaying a phase of the target steering angle calculated in accordance with the detected steering angle. 2. The steering method according to claim 1, wherein the phase of the steering force command value calculated based on the difference between the actual steering angle and the target steering angle is delayed, thereby delaying the phase of the steering force command value with respect to the detected steering angle. 4. The steering method according to claim 1, further comprising delaying the phase using a delay filter. In a steering device in which a steering unit that receives a steering input from a driver and a steering unit that steers steered wheels of a vehicle are mechanically separated, a steering method for steering the steered wheels includes the steps of:
Detects the steering angle of the steering wheel,
An actual steering angle is detected, which is the actual steering angle of the steered wheels.
Calculating a target steering angle of the steered wheels in accordance with the detected steering angle;
calculating a steering force command value for making the actual steering angle coincide with the target steering angle based on a difference between the actual steering angle and the target steering angle;
delaying a phase of the steering force command value with respect to the detected steering angle when an angle ratio, which is a ratio of the target steering angle to the detected steering angle, is large compared to when the angle ratio is small;
generating a steering force for steering the steered wheels in accordance with the steering force command value with a delayed phase;
delaying a phase of the target steering angle calculated in accordance with the detected steering angle, thereby delaying a phase of the steering force command value with respect to the detected steering angle;
a phase of the target steering angle is delayed by adding an integral term of the target steering angle calculated in accordance with the detected steering angle to a proportional term of the target steering angle. 6. The steering method according to claim 5 , wherein the integral term is calculated by integrating only a fluctuation component of the target steering angle, or the integral term is limited by a limit value according to the target steering angle. The steering method according to any one of claims 1 to 6, characterized in that, when the detected steering angle, or the steering angular velocity, steering angular acceleration, or steering angular jerk of the steering angle, the steering force applied to the steering wheel , or a time change of the steering force is less than a predetermined value, a phase of the steering force command value is delayed with respect to the detected steering angle. A steering device for steering steered wheels of a vehicle, in which a steering unit that receives a steering input from a driver and a steering unit that steers the steered wheels of the vehicle are mechanically separated from each other,
A first sensor for detecting a steering angle of a steering wheel;
A second sensor for detecting an actual steering angle, which is an actual steering angle of the steered wheels;
an actuator that generates a steering force for steering the steered wheels;
a controller which sets a larger angle ratio when the vehicle speed is low than when the vehicle speed is high, multiplies the steering angle detected by the first sensor by the angle ratio to calculate a target steering angle of the steered wheels, calculates a steering force command value for making the actual steering angle coincide with the target steering angle based on a difference between the actual steering angle and the target steering angle, and delays the phase of the steering force command value with respect to the detected steering angle by a larger delay amount when the angle ratio, which is the ratio of the target steering angle to the steering angle detected by the first sensor, is large than when the angle ratio is small, and drives the actuator in accordance with the steering force command value whose phase has been delayed by the delay means;
A steering device comprising: A steering device for steering steered wheels of a vehicle, in which a steering unit that receives a steering input from a driver and a steering unit that steers the steered wheels of the vehicle are mechanically separated from each other,
A first sensor for detecting a steering angle of a steering wheel;
A second sensor for detecting an actual steering angle, which is an actual steering angle of the steered wheels;
an actuator that generates a steering force for steering the steered wheels;
a controller which calculates a target steering angle of the steered wheels in accordance with the steering angle detected by the first sensor, calculates a steering force command value for making the actual steering angle coincide with the target steering angle based on a difference between the actual steering angle and the target steering angle, and has a delay means which delays a phase of the steering force command value with respect to the detected steering angle when an angle ratio which is a ratio of the target steering angle to the steering angle detected by the first sensor is larger than when the angle ratio is small, and drives the actuator in accordance with the steering force command value whose phase has been delayed by the delay means;
The controller comprises:
delaying a phase of the target steering angle calculated in accordance with the detected steering angle, thereby delaying a phase of the steering force command value with respect to the detected steering angle;
a steering device for delaying a phase of the target steering angle by adding an integral term of the target steering angle calculated in accordance with the detected steering angle to a proportional term of the target steering angle.

Images