JPH069985B2 - Vehicle steering system controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention controls the motion performance of a vehicle so as to achieve a preset target motion performance by controlling the state quantity of a steering system. The present invention relates to a vehicle steering system control device, and more particularly, to a vehicle steering system control device that uses a detected value of a front wheel cornering force as steering input information necessary for control.

(Prior Art) A conventional vehicle equipped with a mechanical link type steering device is configured to steer the front wheels in accordance with the steering angle of a steering wheel. It is uniformly determined by the specifications, and the exercise performance is unique to each vehicle type.

On the other hand, the applicant of the present invention previously filed Japanese Patent Application No. 59-147018.
(See Japanese Patent Laid-Open No. 61-27763), Japanese Patent Application No. 59-188153,
(See Japanese Patent Application Laid-Open No. 61-67665), Japanese Patent Application No. 59-188158 (see Japanese Patent Application Laid-Open No. 61-67670), and the like, assume a target vehicle having target motion performance, and Based on the element and the equation of motion, the target value of the motion variable corresponding to the steering wheel steering angle and the vehicle speed, that is, the motion variable value representing the motion performance exhibited by the target vehicle, is obtained, and this motion variable target value is determined by the own vehicle (the device A device for controlling the steering angle of the wheels of the vehicle (at least one of the front wheels and the rear wheels) has been proposed so as to be realized by the mounted vehicle.

That is, by using this device, the exercise performance can be freely controlled.

(Problems to be Solved by the Invention) By the way, the inventor of the present application has found the following improvements while further researching the above device.

That is, in general, considering the movement during steering of the vehicle, first, the driver steers the steering wheel, whereby the front wheels are steered and cornering force is generated in the front wheels. The process of yaw and lateral movement occurs.

Therefore, as in the above-described device, in the configuration in which the steering angle of the steering handle is detected and the yaw or lateral movement is known,
The amount of front wheel cornering force must be calculated from the detected steering angle of the steering wheel, and the amount of yaw and lateral motion must be calculated based on this front wheel cornering force. It is possible.

(Means for Solving Problems) In order to solve the above problems, the present invention includes means shown in FIG.

The motion variable target value determination means 102 is based on a target vehicle model having a preset target motion performance, and the cornering force _CF acting on the front wheels detected by the cornering force detection means 100 and the vehicle speed detection means 101. The target value of the motion variable corresponding to the vehicle speed V detected at is obtained.

The control amount generation means 103 determines the control amount S of the state amount of the rear wheel steering system required to realize the motion variable target value based on the front wheel cornering force _CF , the vehicle speed V and the vehicle specifications of the own vehicle. Occur.

The steering system state quantity varying means 104 changes the state quantity of the rear wheel steering system of the own vehicle in accordance with the control quantity S.

(Operation) According to the present invention, the front wheel cornering force is detected and the motion variable target value and the control amount S are obtained by using the detected value C _F of the front wheel cornering force. As compared with a case where the target value of the motion variable and the control amount S are detected by using the detected value of the steering angle, the amount of calculation and the calculation time are reduced, and the control response is improved.

Further, compared to a case where the front wheel cornering force is estimated and obtained from the steering angle of the steering wheel, the vehicle model modeling error can be reduced by detecting the front wheel cornering force.

(Embodiment) The configuration of the first embodiment of the present invention is shown in FIG.

The arithmetic processing unit 1A is configured by a microcomputer or other electric circuit, and detects the steering torque acting on the steering wheel 8 detected by the steering torque sensor (a known torque sensor attached to the steering shaft) 2. The detected value T _C and the vehicle speed V of the vehicle equipped with the apparatus of this embodiment (hereinafter referred to as “own vehicle”) detected by the vehicle speed sensor 3 as the vehicle speed detecting means are input, and predetermined calculation is performed.
The rear wheel steering angle command value _R is output.

The front wheels 9 and 10 are steered to a steering angle corresponding to the steering angle of the steering handle 8 by a mechanical link type steering device 6 similar to that of a conventional vehicle.

The rear wheels 11 and 12 are configured to be steered by a hydraulic steering device 7, and the hydraulic steering device 7 is controlled by the rear wheel steering device 5. The rear wheel steering device 5 controls the hydraulic steering device 7 by changing the hydraulic pressure applied to the hydraulic steering device 7 in accordance with the rear wheel steering angle command value _R input from the arithmetic processing device 1A ( The details are substantially the same as those described in Japanese Patent Application No. 59-188153).

FIG. 3 is a flow chart showing processing executed by the arithmetic processing unit 1A when the arithmetic processing unit 1A is configured by using a microcomputer. The process shown in the figure is repeatedly executed at predetermined time intervals, and the initialization is performed when the ignition switch is turned on.

In the processing of step 21, both the steering torque detection value T _C detected by the steering torque sensor 2 and the vehicle speed detection value V detected by the vehicle speed sensor 3 are read.

Step 22 corresponds to a front wheel cornering force detecting means. In this step, the steering torque T _C read in is read out to obtain a front wheel cornering force C _F. This calculation is expressed by the following equation.

Here, N is the steering gear ratio of the own vehicle, ξ is the trail of the own vehicle, and these values are stored in advance in the memory ( The value of should be obtained in advance and this should be used as a coefficient).

Since the above formula (1) is a simple multiplication, the obtained value of the front wheel cornering force C _F almost coincides with the value of the cornering force actually acting on the front wheel.
That is, although it is indirect, an operation equivalent to detecting the front wheel cornering force _CF by the above calculation can be obtained. Hereinafter, this front wheel cornering force _CF will be referred to as "front wheel cornering force detection value _CF ".

Step 23 corresponds to the motion variable target value determining means, and in the processing of this step, the front wheel cornering force detection value C _F and the vehicle speed V are calculated based on a target vehicle model having a preset target motion performance. The target value of the corresponding motion variable, that is, the target value of the yaw angular acceleration in this embodiment. And yaw rate target Ask for.

The target vehicle model is a mathematical model set by the vehicle specifications and the equation of motion, and by giving the front wheel cornering force detection value C _F and the vehicle speed V, the target vehicle model corresponding to these C _F and V is obtained. The motion state quantity of the model is obtained, and the yaw angular acceleration and yaw rate at this time are calculated as the above yaw angular acceleration target value. And yaw rate target value And

These yaw angular acceleration target values And yaw rate target value Is specifically calculated by the following calculation.

here, : Target vehicle model morate : Yaw angular acceleration of the target vehicle model C _R1 : Rear wheel cornering force of the target vehicle model K _R1 : Rear wheel cornering power of the target vehicle model V _y1 : Lateral speed of the target vehicle model _y1 : Lateral translation of the target vehicle model acceleration L _R1: distance between the wheels and the center of gravity after the target vehicle model M _1: body weight of the target vehicle model I _Z1: a yaw inertia of the target vehicle model.

Next, at step 24 corresponding to the control amount generating means, the yaw angular acceleration target value obtained at step 23 is obtained. And yaw rate target value Is calculated for the rear wheel steering angle command value _R.

The calculation of the rear wheel steering angle command value _R is performed by adding the above-mentioned to the vehicle model (hereinafter referred to as “own vehicle model”) in which the original motion characteristics of the own vehicle are mathematically modeled by the vehicle specifications of the own vehicle and the equation of motion. Front wheel cornering force detection value C _F , vehicle speed V, and the yaw angular acceleration target value And yaw rate target value By substituting.

This calculation is specifically performed by the following calculation.

Where V _y2 : lateral velocity of the vehicle model _y2 : lateral translational acceleration of the vehicle model L _F2 : distance between the front axis of the vehicle model and the center of gravity _LR2 : between the rear axis of the vehicle model and the center of gravity Distance C _R2 : Rear axle cornering force of the own vehicle model I _Z2 : Yaw inertia of the own vehicle model M ₂ : Body weight of the own vehicle model K _R2 : Rear wheel cornering power of the own vehicle model

The rear wheel steering angle command value _R thus obtained is output to the rear wheel steering device 5 in step 25.

The rear wheel steering device 5 constitutes a steering system state quantity varying means together with the hydraulic steering device 7, and an operating oil pressure necessary for setting the actual steering angles of the rear wheels 11 and 12 to the rear wheel steering angle command value _R. Is supplied to the hydraulic steering device 7.

As a result, the actual steering angle of the rear wheels 11, 12 becomes equal to the rear wheel steering angle command value _R , and the actual yaw angular acceleration and yaw rate of the host vehicle at this time are the yaw angular acceleration target value. And yaw rate target value Is equal to That is, the target exercise performance can be realized in the own vehicle.

Next, FIG. 4 shows the configuration of the second embodiment of the present invention. In the figure, the same components as those of the first embodiment shown in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted.

The difference from the first embodiment is that in the first embodiment, the rear wheel steering angle command value _R is output as the control amount of the state quantity of the steering system, whereas in the present embodiment, the steering system is The rear wheel cornering force command value _R is output as the control amount of the state quantity of.

In this embodiment, two lateral acceleration sensors 13 and 14 are provided in addition to the configuration shown in FIG. As shown in FIG. 5, these two lateral acceleration sensors 13 and 14 are attached to the center positions of the front wheels 9 and 10 and the rear wheels 11 and 12, respectively. This can be realized by mounting the sensor so that its sensing direction is oriented in the horizontal axis direction of the vehicle body 60.

Further, the rear wheel steering device 15 follows the rear wheel cornering force command value _R given from the arithmetic processing unit 1B,
The pressure supplied to the hydraulic steering device 7 is adjusted, and the rear wheel steering device 15 and the hydraulic steering device 7 constitute a steering system state quantity varying means. The adjustment of the supply pressure to the device 7 is performed by servo control.

That is, the rear wheel steering device 15 detects the rear wheel cornering force command value _R given from the arithmetic processing unit 1B and the cornering force actually acting on the rear wheels 11, 12 given from the rear wheel cornering force detection circuit 16. Value (hereinafter referred to as "rear wheel cornering force detection value") C
Input _R and adjust the supply pressure to the hydraulic steering device 7 so that the deviation between _R and C _R becomes zero.

FIG. 6 is a flow chart executed by the arithmetic processing unit 1B. This processing is repeatedly executed at predetermined time intervals, and initialization is performed when the ignition switch is turned on.

In the flow chart, steps that perform the same processing as the steps in the flow chart shown in FIG. 3 are assigned the same reference numerals and explanations thereof are omitted.

Step 31 corresponds to the motion variable target value determining means. In this step, the target vehicle model is used to correspond to the front wheel cornering force detection value C _F and the vehicle speed V, as in step 23 in the first embodiment. Find the target value of the exercise variable. In this example, as the target value of the motion variable,
Target value of yaw angular acceleration Ask for. The specific calculation is the same as the formulas (2) to (7).

Next, in step 32 corresponding to the control amount generating means, the yaw angular acceleration target value is added to the own vehicle model. By substituting To obtain the cornering force of the rear wheels required to realize the
_R processing is performed. This calculation of _R is expressed by the following equation.

In this case as well, the front wheel cornering force detection value C _F is used, and since the rear wheel steering command value does not have to be obtained as in the first embodiment, the calculation in the own vehicle model becomes extremely simple. ing.

Then, in step 33, the calculated rear wheel cornering force command value _R is output to the rear wheel steering device 15.

On the other hand, the rear wheel cornering force detection circuit 16 obtains the rear wheel cornering force detection value C _R from the front wheel lateral acceleration α _F and the rear wheel lateral acceleration α _R detected by the two lateral acceleration sensors 13 and 14. The operation of outputting to the rear wheel steering device 15 is performed.

The calculation performed by the rear wheel cornering force detection circuit 16 is represented by the following equation.

C _R = {(Ml _F 1 _R −I _Z ) α _F + (Ml _F ² + I _Z ) α _R }
/ 2 (l _F + l _R ) ² (14) Here, M: vehicle body weight of own vehicle I _Z : yaw inertia of own vehicle, and l _F and l _R are lateral as shown in FIG. The distance between the acceleration sensor 13 and the center of gravity 61 of the vehicle body 60 and the distance between the lateral acceleration sensor 14 and the center of gravity 61.

Actually, the above equation (14) is expressed in the form of (Aα _F + Bα _R ) (A and B are constants), and therefore, it is possible to use the two multipliers and the adder, the differential amplifier, or the like to realize almost all in real time. It can be calculated without error. Accordance connexion, rear wheel cornering off Orth detection value C _R will equal the actual rear wheel cornering off Orth value.

Instead of the rear wheel cornering force detection circuit 16, the arithmetic processing unit 1B may perform the calculation of the above equation (14) to obtain the rear wheel cornering force detection value C _R.

Further, in each of the above-described embodiments, as a means for detecting the front wheel cornering force, the steering torque T _C is detected by the torque sensor, and the front wheel cornering force is indirectly detected from the detected steering torque T _C. Although shown, of course, a sensor for directly detecting the front wheel cornering force can be used as the front wheel cornering force detecting means, or other indirect detecting means may be used.

Furthermore, in each of the above-described embodiments, the example in which the rear wheel steering angle is controlled as the state quantity of the steering system as the control target is shown, but in addition to this, both the front wheel steering angle and the rear wheel steering angle are controlled. (Suggested in Japanese Patent Application No. 59-188153), those that control the steering gear ratio (Suggested in Japanese Patent Application No. 60-73839), and similar devices that control the steering system using the own vehicle model. Can be applied.

(Effects of the Invention) As described in detail above, the present invention detects the front wheel cornering force and controls the target value of the motion variable and the rear wheel steering system state quantity by using the detected front wheel cornering force. Since the steering angle of the steering wheel is detected and the target value of the motion variable and the control amount are calculated using the detected steering angle, the calculation amount and the calculation time are calculated. Is low and the control response is high.

Further, as compared with the case where the front wheel cornering force is estimated and obtained from the steering angle of the steering wheel, the amount of calculation in the vehicle model is smaller when the front wheel cornering force is detected. The modeling error of is reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a block diagram of a first embodiment of the present invention, FIG. 3 is a flow chart showing processing executed in the arithmetic processing unit in FIG. 2, and FIG. Is a configuration diagram of a second embodiment of the present invention, FIG. 5 is a diagram showing a mounting position of the lateral acceleration sensor in FIG. 4, and FIG. 6 is a process executed by the arithmetic processing unit in FIG. It is a flow chart. 100 …… Front wheel cornering force detecting means 101 …… Vehicle speed detecting means 102 …… Motion variable target value determining means 103 …… Control amount generating means 104 …… Steering system state quantity varying means 1A, 1B …… Computational processing device 2 ... … Steering torque sensor, 3 …… Vehicle speed sensor 5,15 …… Rear wheel steering device 7 …… Hydraulic steering device 8 …… Steering handle 9,10 …… Front wheel, 11,12 …… Rear wheel 13,14 …… Lateral acceleration sensor T _C …… Steering torque, V …… Vehicle speed _R …… Rear wheel steering angle command value _R …… Rear wheel cornering force command value C _F …… Front wheel cornering force detection value ...... Yaw rate target value ...... yaw angle acceleration target value C _R ...... rear wheel cornering off Orth detection value

Claims (2)

[Claims] 1. A front wheel cornering force detecting means for directly or indirectly detecting a cornering force acting on a front wheel, a vehicle speed detecting means for detecting a vehicle speed, and a target vehicle model having a preset target motion performance. A motion variable target value determining means for determining a target value of a motion variable corresponding to the detected value of the front wheel cornering force and the detected value of the vehicle speed, and the detected value of the front wheel cornering force and the detected value of the vehicle speed and the own vehicle A control amount generating means for generating a control amount of a state amount of a rear wheel steering system necessary for realizing the motion variable target value by using specifications, and a rear wheel of the own vehicle corresponding to the control amount. A steering system control device for a vehicle, comprising: steering system state quantity varying means for changing a state quantity of the steering system. 2. The front wheel cornering force detecting means detects a steering torque acting on a steering wheel and indirectly obtains a front wheel cornering force based on a detected value of the steering torque. The vehicle steering system control device according to claim 1.