JPS62247979A - Actual steering angle control device for vehicle - Google Patents

Abstract

PURPOSE:To perform a stable control by adjusting the wheel steering angle of an objective car in such a way that the dynamic characteristics of the objective car follows the dynamic characteristics possessed by a standard model whereby changing a feed forward control system over to a feed back control system as required. CONSTITUTION:A target value S3 for the quantity of motion state is operated by a means 102 based on both a driver's command S1 detected by a means 100 and a car speed S2 detected by a means 101. And a target value S4 for the manipulated variable of a steering angle for an objective wheel which has to be controlled in order to accomplish the target value S3 with an objective car, is determined by a means 103. Furthermore, an auxiliary manipulated variable S6 to the target S4 in response to the difference between the target value S3 and the detected value S5 found by a means 104 for the quantity of motion state, is determined by a means 105. Then the auxiliary manipulated variable S6 is added to the target value S4 for correcting the target value S4 by a means 106. And then, the actual steering angle of the objective wheel to be controlled is adjusted by a means 107 in accordance with a target value S7 for the manipulated variable of the corrected steering angle.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an actual steering angle control device for a vehicle that controls the dynamic characteristics of a vehicle by adjusting the actual steering angle of wheels.

(Prior art) Vehicles equipped with conventional mechanical link steering devices are configured to steer the front wheels in response to the amount of steering of the steering wheel, and the dynamic performance associated with steering depends on the vehicle. The driving performance is uniformly determined by the vehicle specifications.
It is unique to each car model.

On the other hand, the applicant of the present application previously filed a patent application filed in
In No. 1158, a target vehicle model (normative model) having target dynamic performance is assumed, and a motion state corresponding to the steering wheel steering amount and vehicle speed is determined based on the vehicle specifications and equation of motion regarding the target vehicle model. The target value of the quantity, that is, the amount of motion state exhibited by the target vehicle model is determined, and the wheels (front wheels and rear wheels) of the own vehicle are determined so that the target value of the amount of motion state is realized in the own vehicle (vehicle equipped with the device).
We are proposing a device to control the rudder angle of the

In other words, by using this device, it is possible to freely control exercise performance.

(Problems to be Solved by the Invention) By the way, the inventors of the present application discovered the following improvement points while further researching the above device. In other words, the above device has the above-mentioned motion state quantity target value. , is realized as the amount of motion state of the own vehicle, but at this time,
Since there is no feedback of the vehicle's motion state, it is vulnerable to external disturbances and environmental changes.

Control accuracy and stability are particularly required for control objects such as vehicles, which are subject to large disturbances and environmental changes due to changes in moving speed, changes in road surface or climate, etc.

Therefore, it is conceivable to adopt a configuration in which the amount of motion state of the own vehicle is fed back, but in this case, there is a possibility that the following disadvantages may occur.

That is, feedback control is highly dependent on the sensor that detects the amount of motion state of the own vehicle, and if a failure occurs in the sensor, the control may become uncontrollable. In addition, when driving with large lateral acceleration or on a road surface with a small road friction coefficient, the dynamic characteristics of the own vehicle change significantly, so the deviation between the amount of motion state of the own vehicle fed back and the target value of the amount of motion state may become large and feedback control may become unstable.

(Means for solving the inter-combining point) In order to solve the above-mentioned inter-combining point, the present invention includes means shown in FIG. 1.

The motion state quantity target value calculation means 102 is a reference model formed by mathematically modeling the characteristics characterized by the driver's steering command S□ detected by the steering command detection means 100 and the vehicle speed S2 detected by the vehicle speed detection means 101. , and find at least one type of target value of the amount of motion state that the vehicle is trying to achieve.

Based on the target value 38 of the motion state quantity, the steering angle operation amount target value determining means 10B determines at least one of the front wheels and the rear wheels necessary for realizing the target value S of the motion state quantity in the own vehicle. A target value S of the manipulated variable of the steering angle of the wheel to be controlled is determined.

The motion state quantity detection means 104 detects a motion state quantity of the same type as the target value S of the motion state quantity among the motion state quantities occurring in the own vehicle.

The auxiliary operation amount determining means 105 determines an auxiliary operation amount S6 for the target value S of the steering angle operation amount, corresponding to the difference between the target value S of the motion state amount and the detected value S of the motion state amount. Determine.

The target value correcting means 106 adjusts the target value 5 of the manipulated variable of the steering angle.
4VC and the auxiliary operation 1tS6 are added to correct the target value S of the steering angle operation amount.

The wheel actual steering angle adjusting means 107 adjusts the actual steering angle of the control target wheel according to the corrected target value S7 of the manipulated variable of the steering angle.

(Operation) The present invention adjusts the actual steering angle of the wheels to be controlled in order to achieve the target dynamic characteristics set in the reference model in the own vehicle.

The actual steering angle of the wheel to be controlled is adjusted by the steering angle operation amount target value determining means 108, mainly through feedforward control. As a result, it is possible to maintain reliable system stability and perform control without delay, which is a feature of feedforward control. By assisting the above feedforward control with feedback control, it is possible to correct disturbances in the feedforward control due to external disturbances or environmental changes.

(Example) FIG. 2 shows the configuration of an embodiment of the present invention.

The arithmetic processing bag kl is constructed using a microcomputer or other electric circuit, and receives the steering angle θ6 of the steering wheel 8 detected by the steering angle sensor 2 as a steering command input.

In addition, the vehicle speed V detected by the vehicle speed sensor 8 and the detection signals of the yaw rate actually occurring in the host vehicle detected by the yaw rate sensor 18 are input to the calculation processing bag [1.

Then, the arithmetic processing bag fil executes predetermined arithmetic processing based on each of the above-mentioned inputs, and performs a target value for the operation amount of the steering angle of the rear wheels 11 and 12 (hereinafter referred to as "rear wheel steering angle target value"). ) JR
Output.

The rear wheels 11, 12 are configured to be steered by a hydraulic steering device 7. This hydraulic steering device 7 is controlled by a rear wheel steering device ff115.

The rear wheel steering device it5 changes the oil pressure applied to the hydraulic steering device 7 in accordance with the rear wheel steering angle target value RK inputted from the calculation processing bag fil, so that the actual steering angles of the rear wheels 11 and 12 become the rear wheel steering angles. It operates to match the steering angle target value 7R (details are described in %Gan Sho 59-188158).
.

The front wheels 9 and 10 are equipped with a conventional mechanical link steering system f.
At t6, the vehicle is steered by the steering wheel 8.

FIG. 8 is a block diagram showing the configuration of the arithmetic processing device l.

The arithmetic processing device l includes a reference model 21 and a steering angle calculation unit 22.
, an auxiliary steering angle determining section 28 , and a target value correcting section 24 . Of course, these configurations can be realized through processing by computer software.

The reference model 21 is a mathematical model of a preset target dynamic characteristic, and in this embodiment, it is a reference model for the response characteristic of the yaw rate. This reference model 21 inputs the steering angle θ and the vehicle speed V, calculates the yaw rate and yaw angular acceleration that the vehicle is trying to achieve based on these inputs, and sets these as the yaw rate target 11.
It is output as the yaw angular acceleration target value V.

The reference model 21 may have the same settings as the target vehicle model described in Japanese Patent Application No. 188158/1982, or may have the same settings as the target vehicle model described in Japanese Patent Application No. 59-188158. However, τ is a constant that determines the responsiveness, k (v5 is a constant that sets the target value of the steady yaw rate gain (ψ0/,) at each vehicle speed, and K is the steady yaw rate value,
(θ8° is a steady value of the steering angle).

The steering angle calculation unit z2 is equipped with a vehicle model that is a mathematical model of the dynamic characteristics of the vehicle, and this vehicle model is provided with the above-mentioned yaw rate target value, yaw angular acceleration target value V, and steering angle θ8.
and vehicle speed V, and find the rear wheel steering angle necessary to achieve the target yaw rate value and the target yaw angular acceleration value for the own vehicle. This calculated rear wheel steering angle is output as a rear wheel steering angle target value -Ro.

The auxiliary steering angle determining unit z8 determines the difference e (-1141) between the yaw rate target direct number determined by the reference model 21 and the yaw rate of the own vehicle detected by the yaw rate sensor 18.
Corresponding to this difference e, the auxiliary steering angle 70,2 for the rear wheel steering angle target value is determined. To determine this auxiliary steering angle aRm, a control calculation unit 2Ba having a predetermined transfer characteristic H(13) and a limiter 281) that limits the magnitude of the auxiliary steering angle aR2 to within a predetermined value are used. .

The control calculation section 28a is configured to perform a P calculation as shown in FIG. 4(a), for example.
Control, mechanical control shown in the same figure (b), P shown in the same figure (c) K
Configure using either I control.

For example, when the range of the rear wheel steering angle target value 'R+ determined by the steering angle calculating section 22 is ±2°, the limiter 28b sets the range of the auxiliary steering angle 'R2 to ±0.2'. Restrict.

The target value correction unit 24 adds the auxiliary steering angle aRz to the rear wheel steering angle target value 7 determined by the steering angle calculation unit 22,
The rear wheel steering angle target value 'R1 is corrected. Then, this corrected rear wheel steering angle target value a(-JR.

+'R2) is applied to the rear wheel steering device 5.

With the above control, in this embodiment, during normal driving,
When the feedforward control is stable, the yaw rate target value number and the yaw angular acceleration target value V are accurate (and can be realized by the own vehicle without delay, eCoO1, that is, i→
Therefore, the auxiliary steering angle becomes JR220. This is rear wheel 11
．． This is equivalent to performing only feedforward control in which the actual steering angle of 12 is controlled using only the rear wheel steering angle target value 7R□ determined by the steering angle calculating section 22.

Next, if the vehicle's motion is disturbed by disturbances or environmental changes, feedforward control becomes unstable, so e)
0, an auxiliary steering angle a R2 is formed according to the thickness of the difference e between cloudy and cloudy, and □ is corrected to the target rear wheel steering angle value. As a result, the feedforward control using the steering angle calculating section 22 is modified by the feedback control using the auxiliary steering angle determining section 28, and it is possible to prevent the control from becoming unstable due to disturbances or the like.

In addition, since the range of the auxiliary steering angle J Rz is limited by the limiter 28b, even if the yaw rate sensor 18 should fail, the auxiliary steering angle will not become larger than necessary, resulting in a fail-safe condition. You can get the effect. That is, as mentioned above, the range of the rear wheel steering angle target value 'R1 is ±2.
If the auxiliary steering angle J RIB is ±0.2°, even if the yaw rate sensor 18 fails, the amount of correction for the rear wheel steering angle target value 7R will be 0.2° at most. The driver can also cope with such a change in the steering angle without compromising safety.

Note that the present invention is not limited to the configuration shown in the above embodiment, and in addition, the front wheels 9.10 and the rear wheels 11.12
Similarly, the actual steering angle can be adjusted by the control and control by the arithmetic processing unit, and the target dynamic characteristics can be realized by the own vehicle by adjusting the actual steering angles of both the front wheels and the rear wheels. . In this case, the steering angle calculating section 22 determines the front wheel steering angle target value and the rear wheel steering angle target value, and the auxiliary steering angle determining section 28 determines the auxiliary steering angle and the rear wheel steering angle with respect to the front wheel steering angle target value. The configuration is such that the auxiliary steering angle is determined relative to the target value.

Further, the configuration of the reference model 21 is not limited to that of the above embodiment, and may be one that obtains target values of other motion state quantities (for example, a target value of lateral acceleration, a target value of lateral velocity, etc.) Alternatively, the target value of the motion state quantity of multiple stocks (for example, 2aI of the target value of yaw rate and the target value of lateral velocity)
etc.).

Further, the limiter 2B+) does not directly limit the magnitude of the auxiliary steering angle 'Rig as in the above embodiment, but is placed in front of the control calculation section 28a to control the magnitude of the deviation e. The magnitude of the auxiliary steering angle "R2" may be indirectly limited by this. It is also possible to make the limit amount of the limiter 28b smaller as the vehicle speed increases to achieve stability.

(Effects of the Invention) According to the present invention, the target dynamic characteristics set in the reference model can be realized as the dynamic characteristics of the own vehicle by adjusting the wheel steering angle of the own vehicle.

The present invention performs adjustment control of the wheel steering angle mainly by feedforward control, and when the feedforward control becomes unstable due to disturbances, environmental changes, etc., the feedforward control is performed by a feedback control system. By providing assistance, stable control can be achieved at all times.

Brief explanation of the four aspects: FIG. 1 is a block diagram of the present invention; FIG. 2 is a block diagram of an embodiment of the present invention; FIG. 8 is a block diagram showing the configuration of the arithmetic processing device in FIG. 2; FIGS. 4(a) to 4(C) are block diagrams showing different configuration examples of the control calculation section in FIG. 8.

・100...Steering command detection means 101...Vehicle speed detection means 102...Motion state quantity target value calculation means 108...Steering angle operation amount target value determination means 104...Motion state quantity detection means 105. ...Auxiliary operation amount determination means 106...Target value correction means 107...Wheel actual steering angle adjustment means l...Arithmetic processing unit IL2...Steering angle sensor 8...
・Vehicle speed sensor 5...Rear wheel steering device 8...Steering handle 9, lO...Front wheels 11, 12...Rear wheel 18...Yaw rate sensor 21...Reference model 2
2... Rudder angle calculation section 28... Auxiliary steering angle determination section 24... Target value correction section θ8... Steering angle V... Vehicle speed ÷... Yaw rate target value V... Yaw angular acceleration Eye value ψ...
Yaw rate detection value 'R1'' Rear wheel steering angle target value J R2
...Auxiliary steering angle 8...Target value of rear wheel steering angle (after correction) e...Difference between target yaw rate value and detected yaw rate Patent applicant Nissan Motor Co., Ltd. Figure 1/2 7 If No. Figure 3

Claims (1)

[Claims] 1. Steering command detection means for detecting a steering command by a driver; vehicle speed detection means for detecting vehicle speed; a motion state quantity target value calculating means for calculating at least one type of target value of the motion state quantity to be achieved by the own vehicle based on the detected value of the motion state quantity; Steering angle operation amount target value determining means for determining a target value of the steering angle operation amount of at least one of the front wheels or the rear wheels to be controlled, which is necessary for realizing the target value of the motion state quantity in the own vehicle; A motion state quantity detection means for detecting a motion state quantity of the same type as a target value of the motion state quantity among the motion state quantities occurring in the own vehicle; Correspondingly, an auxiliary operation amount determination means for determining an auxiliary operation amount with respect to a target value of the steering angle operation amount; and a wheel actual steering angle that adjusts the actual steering angle of the control target wheel in accordance with the target value of the steering angle operation amount after being corrected by the target value correcting means. 1. An actual steering angle control device for a vehicle, comprising: adjusting means. 2. The actual steering angle control device for a vehicle according to claim 1, wherein the auxiliary operation amount determining means includes a limiter that limits the absolute value of the auxiliary operation amount within a predetermined value.