JPS61226368A - Steering angle control device for vehicle - Google Patents

Abstract

PURPOSE:To accurately realize the maneuverability of a target car without being affected by road condition changes and to obtain invariably stable maneuverability by compensating car maneuverability changes fluctuating in response to road condition changes. CONSTITUTION:A microcomputer 1 is fed with the car speed V detected by a car speed sensor 3 and the steering quantity thetaS of a steering handle 8 detected by a handle steering quantity sensor 2 and calculates the maneuver variable target value, front wheel steering angle target value deltaF, and rear wheel steering angle target value deltaR. The microcomputer 1 is fed with the road condition detection signal DL from a road condition detector 13, and it compensatingly calculates the front wheel steering angle target value deltaF and rear wheel steering angle target value deltaR in response to the road condition status based on this road condition detection signal DL.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a steering angle control device for a vehicle that can freely control the motion performance of a vehicle during steering.
The present invention relates to a vehicle steering angle control device that improves control accuracy by compensating for changes in vehicle dynamic characteristics that vary with changes in road surface conditions.

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

In response to this, the applicant of the present application previously filed a patent application in 1983-147.
No. 018, Japanese Patent Application No. 188158, Japanese Patent Application No. 1881, Japanese Patent Application No. 1881-
No. 188158, etc., assuming a target vehicle with a target dynamic performance, based on the vehicle specifications and equation of motion regarding the target vehicle, target values of motion variables corresponding to the steering wheel steering amount and vehicle speed, that is, the target vehicle The steering angle of the vehicle's wheels (at least one of the front wheels or rear wheels) is determined so that the vehicle (vehicle equipped with the device) achieves the motion variable target value that represents the motion performance exhibited by the vehicle. We are proposing a device to control this.

In other words, by using this device, for example, even if the own vehicle is a sedan type vehicle, if the target vehicle is set to a sports car type vehicle, it is possible to set the target vehicle to a sports car type vehicle even though the vehicle body structure etc. is a sedan type vehicle. It is possible to freely control exercise performance, such as maintaining exercise performance.

(Problems to be Solved by the Invention) By the way, the inventor of the present application discovered the following improvement point while conducting further research on the above-mentioned device.

That is, in the above device, in order to calculate the motion variable target value and the steering angle target value for controlling the steering angle of the wheels, the steering amount of the steering wheel and the vehicle speed are input as basic variables, and these basic variables are input. Although this is done based on variables, the driving characteristics of the vehicle change depending on the road surface conditions (road surface irregularities, etc.), which has the disadvantage that the accuracy of achieving the target driving performance varies.

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

The motion variable target value calculating means 102 calculates the steering wheel steering amount θ8 detected by the steering wheel steering amount detecting means 100 and the vehicle speed detecting means 101 based on a motion equation regarding a target vehicle having a preset target motion performance.
The target value M of the motion variable corresponding to the detected vehicle speed V is determined.

The wheel steering angle target value calculation means 103 calculates the motion variable target value M from the motion variable target value M and the vehicle specifications of the host vehicle.
A target value δ of the wheel steering angle of at least one of the front wheels or the rear wheels to achieve this is determined.

The wheel steering means 104 steers the corresponding front wheel or rear wheel to the wheel steering angle target value δ.

Then, the vehicle specification correction means 106 corrects the own vehicle specifications used by the steering angle target value calculation means 108 according to the road surface condition detected by the road surface condition detection means 105.

(Operation) The motion variable target value M obtained by the motion variable target value calculation means 102 is realized by the wheel steering angle target value calculation means 1oa and the wheel steering means 104.
The vehicle is controlled to have the motion characteristics of the target vehicle.

Further, at this time, the vehicle specifications of the own vehicle are corrected by the vehicle specification correction means 106 in accordance with the road surface condition, so that even if a change in the road surface condition occurs, the accuracy of realizing the motion characteristics of the target vehicle does not change. .

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

The microcomputer 1 inputs the vehicle speed V detected by the vehicle speed sensor 3 and the steering amount θ6 of the steering wheel 8 detected by the steering wheel steering amount sensor 2, and calculates the motion variable target value and calculates the front wheel steering angle and front wheel turning. The device 4 is a device that performs steering control of the front wheels 9 and 10 based on the data of the front wheel steering angle target value δF given from the microcomputer 1; This device performs steering control of the rear wheels 11 and 12 based on data of the rear wheel steering angle target value δR.

It is the hydraulic steering devices 6 and 7 that actually steer the front wheels 9.10 and the rear wheels 11.12.

The above-mentioned steering device 4, rear wheel steering device 5, and hydraulic steering device [6, 7] have a configuration as shown in FIG. 3, for example.

The hydraulic steering devices 6 and 7 have two pistons 82
．． 33, and whose both ends are connected to tie rods (shown in the figure), is moved in the axial direction by creating a difference between the working oil pressures of the left and right hydraulic chambers 84, 35, thereby steering the wheels.

In addition, within the central chamber 37, repulsion plays 88, 39 which are biased in left and right opposite directions by a spring 86 are loosely fitted onto the shaft 81, and these are connected to the left and right hydraulic chambers 84. This is for returning the shaft 81 to its original neutral position when the hydraulic pressure of a5 is removed.

The front/rear wheel steering devices 4 and 5 are composed of a torsion/idle driver 21, a control valve 22, an oil pump 26, and an oil tank 27.

The control valve 22 is connected to the hydraulic steering device 6
, 7 oil passages 28, 29 leading to left and right oil pressure ia4, 35
It is equipped with a spool valve 25 that adjusts the amount of hydraulic oil flowing into these oil passages 28 and 29. This spool valve 25 has electromagnetic solenoids 28 and 24 at the left and right ends.
It is loosely fitted into the left and right hydraulic chambers 84°3 and moves in the axial direction depending on the magnitude of the magnetic force of the electromagnetic solenoids 28 and 24.
Adjust the amount of hydraulic oil given to 5.

The solenoid driver 21 supplies a current signal proportional to the front/rear wheel steering angle target value δ7°δ given from the microcomputer 1 to either the left or right electromagnetic solenoid 28.24. In this case, control is performed by switching the electromagnetic solenoid that applies current to the left or right depending on the steering direction of the wheels.

The road surface condition detection signal DI from the road surface condition detector 13 is input to the micro combinator L.
The micro combiator 1 performs a correction calculation corresponding to the front wheel steering road surface condition based on the road surface condition detection signal DL.

The road surface condition detector 18 mainly detects the unevenness of the road surface, and uses a vibration sensor or emits light, ultrasonic waves, microwaves, etc. toward the road surface, and determines the road surface condition from the reflected state. Exploration type sensors, etc., are used.

In this embodiment, the former vibration sensor is used.

This device uses a piezoelectric element in the attachment part of the shock absorber or suspension strut to electrically detect the vibrations transmitted from the wheel.
9-819f1).

The circuit configuration is as shown in FIG. The output signal S from the piezoelectric element 131 is separated into two systems and input to a bypass filter 182 and a low pass filter 134.

Vehicle body vibrations are classified into unsprung vibrations and sprung vibrations.
Unsprung vibration is around 10H2, sprung vibration is 1-3H
It is about 2. In the output signal S0 of the piezoelectric element 181, a composite imaging component of unsprung imaging and sprung mass vibration appears, so this is separated by the above-mentioned high-pass filter 182 and low-pass filter 184.

Therefore, the pass frequency of the bypass filter 132 is 3 to 5.
Hz or higher, the passing frequency of the low-pass filter 184 is 3
It is set to below ~5 Hz.

Then, the output signal S of the bypass filter 182.

The output signal S8c of the low-pass filter 184 is full-wave rectified and smoothed by the rectifier/smoothing circuit 123 or 186, respectively, and the voltage No. 1 S or S6 corresponding to the signal level of the output signal S or νGtS, is converted to However, the output signal S of the low-pass filter 184,
Since this also includes a DC component, a bypass filter (passage frequency 0, I Hz or higher) 185
is interposed after the low-pass filter 11114.

Output signal S of the above two rectifier/smoothing circuits 183 and 116
, , S6 corresponds to the magnitude of the unsprung vibration or the magnitude of the sprung mass vibration, so these signals 8B
, S6 are connected to comparators 18 each having a different reference level.
The level is determined by inputting the information to F-140. The signal S6 is
The reference level (reference voltage) is input to the VR engineer's comparator 187 and the reference level vR1(F) comparator 138, and the signal S6 is input to the reference level V comparator 139 and then to the /lz7R4 comparator 140. is input. Here, 1vRi -VHB, tP tsuVRI > vRg # vas > V
It is set to H2.

Each of the comparators 187 to 140 has a high level (hereinafter referred to as
In other cases, a low level signal (hereinafter referred to as 1'-L level) is output. By combining the outputs A□r4 of the two comparators 1197 and 188, the magnitude of the unsprung vibration can be discriminated into eight levels: "large, medium, and small."

That is, when the unsprung vibration is small, the level of the signal S is low and the outputs A and A are both at the L level, and when the unsprung vibration is large, the outputs A1, AB, and A are both at the H level. Therefore, when the output A□ is at the L level and the output A is at the H level, it can be determined that the unsprung vibration is moderate. Similarly, comparators 1199, 14
The magnitude of the sprung mass vibration can be distinguished into three levels from the combination of output B and B of 0.

FIG. 5 is a flowchart showing the processing executed by the microcomputer 1. The operation of this embodiment will be explained below along with the explanation of this flowchart.

The process shown in FIG. 5 is repeatedly executed every predetermined time period Δ, and initialization is performed when the ignition switch is turned on and power is supplied.

In the process of step 201, the road surface condition detection signal DL output from the road surface condition detector 18 is read. this is,
As mentioned above, the four output signals A□.

Mu3. Input as 4-bit data of B-1 B2.

Then, in the next step 202, the road surface condition is discriminated into six types based on the read road surface condition detection signal DL, and according to the discrimination result, one of the own vehicle specifications used in step 205, which will be described later, is determined. The front wheel cornering power KF and rear wheel cornering power KR2 are corrected.

That is, first, from the combination of the levels of the four output signals A□, A, , B+Bs included in the road surface condition detection signal DL, it is determined whether the unsprung vibration is "large" or "large" as described above.
``Medium'', ``Small'' and ``Large'', ``Medium'', ``Small'' of the sprung mass vibration.

The combination of the magnitudes of the unsprung vibration and sprung mass vibration is
There are six types as shown in Table 1. These six combinations are obtained under different road surface conditions, for example:
Each combination occurs under the road surface conditions shown in Table 1.

Here, a "good road" refers to a smooth road surface with no irregularities, such as an asphalt pavement, and a "rough road surface"
``Kuriishi/manhole road'' refers to a road surface with relatively few irregularities but with more road noise than normal paved roads, and ``Kuriishi/manhole road'' refers to a road with chestnut-shaped stones embedded in concrete or a series of manholes. It is a good path. In addition, ``-hysteresis'' refers to a situation where the wheels pass over relatively large irregularities such as the remains of puddles.

Note that rOJ in Table 1 indicates the determination results of "large", "medium", and "small" unsprung vibration and sprung mass vibration.

Then, depending on which of the above six road surface conditions the road surface condition is, the values of the cornering power KF of the front wheels of the own vehicle and the cornering power KRS of the rear wheels of the own vehicle are determined. For example, as shown in Table 1, when KFtl + KH2 when driving on a good road is used as a reference (i.e., 100%), KH2 under other road conditions,
By setting the KH2 ratio in advance, the appropriate KF can be set according to each road surface condition! l Determine KRfA.

Next, in the process of step 203, the data of the steering wheel steering amount θ8 and the data of the vehicle speed V input from the steering wheel steering amount sensor 2 and the vehicle speed sensor 3 to the micro combinator 1 are read.

In the next step 204, the target vehicle specifications stored in the memory are used to set the target values of the motion variables (in this embodiment, the target value φ of the yaw angular acceleration and the target value YG of the centripetal G). An operation is performed to determine the

The above target vehicle specifications are based on the assumption that the target vehicle has the desired driving performance that the own vehicle (vehicle equipped with the device of this embodiment) is intended to achieve.For example, if the own vehicle is a sedan, a sports car is etc.), and the vehicle specifications that determine the motion characteristics of this target vehicle are set as the target vehicle specifications.

In this embodiment, the following vehicle specifications are used as target vehicle specifications.

Iz work: Yaw inertia M of the target vehicle = Vehicle weight L of the target vehicle: Wheelbase LF of the target vehicle; Distance between the front axle and center of gravity of the target vehicle LR work: Distance between the rear axle and center of gravity of the target vehicle 1g□: King pin rotation inertia of the target vehicle Ks□: Steering rigidity of the target vehicle DK□: Steering system viscosity coefficient ξ of the target vehicle: Trail N of the target vehicle: Steering gear ratio of the target vehicle Ky: Front wheels of the target vehicle Cornering power KR□: Cornering power of the rear wheels of the target vehicle, and calculations of the yaw angular acceleration target value pot and the centripetal G target value YG are performed according to the following formula.

1'IF1 ”” NIKSl (θS −Nxa
Fl)-DKx'Fx-2ξ10F ・・・・・・
......(υMl(y,+9',V)-207,+
20H1--・-" (2) Engineering Zlψz -2LFI
CFl-2LR10R1..."""...(8) βF
Yo-δF knee (t-work+L1r19'1)/V...
・・・・・・・・・・・・ (4) βR any-'t knee L
Rtφ, )/V ・・・・・・・・・・・・ (
5) OFl = KFlβF0...
・・・・・・・・・・・・ (6) CR□-KR□βR engineering 1
・・・・・・・・・・・・ （7）ψ
−ψl ・・・・・・・・・・・・
・ (8) y, −yyo+ψ, ■ ・・
・・・・・・・・・−(9) Here, δF: Front wheel steering angle of the target vehicle (assuming that the target vehicle is a two-wheel steered vehicle) φ,: Meal rate of the target vehicle φ: Front wheel steering angle of the target vehicle Me angular acceleration 9 □: Lateral speed of target vehicle y0 = Lateral acceleration of target vehicle βFl ' Sideslip angle of front wheels of target vehicle βR: Sideslip angle of rear wheels of target vehicle CF: Cornering force of front wheels of target vehicle CR: Cornering force of the rear wheels of the target vehicle φ: Yaw angular acceleration target value M: Centripetal G target value.

Equations (1) to (3) above are equations of motion for the target vehicle, and in order to solve these equations, four integral operations are required for each Δ.
) -A(t)+Δt@1(t) An appropriate integration method is used depending on the required integration precision, such as the rectangular integration method or the Rungekutta method.

The yaw angular acceleration target value ψ and centripetal G target value YG obtained in this way are the yaw angular acceleration and centripetal G of the target vehicle corresponding to the steering wheel steering amount θ8 and the vehicle speed V, and these motion variables By realizing the target values GE and YG in the own vehicle, the own vehicle will possess the driving performance of the target vehicle.

Next, in the process of step 205, calculations are performed to obtain target values δR of the front wheel steering angle and rear wheel steering angle necessary for realizing the above-mentioned yaw angular acceleration target value φ and centripetal G target value YG in the own vehicle.

This calculation is performed by substituting the above-mentioned yaw angular acceleration target value φ and centripetal G target value YG into a calculation representing the motion characteristics of the own vehicle using the vehicle specifications of the own vehicle.O The own vehicle used here The specifications are determined in step 202 above.
In addition to the corrected front wheel cornering power KF and the rear wheel cornering power KR8 determined by n, constants stored in advance in the memory are used. KFi
+ Vehicle specifications other than KRi are as follows.

``Zz'' Yaw inertia M of own vehicle: Weight of own vehicle: Wheelbase LFa of own vehicle ``Distance between front axle and center of gravity of own vehicle LR2: Distance between rear axle and center of gravity of own vehicle; The front wheel steering angle target value 5 and the rear wheel steering angle target value 5 are obtained by the following calculations.

βF2 ”” Cys/Kya hit...
... Song (12) βR1I-an, /xR, ...
Song...(13) δ1-βl ” (Vg ” LFzt
Ps )/V −= (14) Outside − βR1” (V
g-”Rgφ, )/V −・−・−−−−−−(15
) However, ;, -? φ, −φ□.

Here, CFg' Cornering force of the front wheels of the own vehicle 'R2' Cornering force of the rear wheels of the own vehicle β, 2: Side slip angle of the front wheels of the own vehicle, : Side slip angle of the rear wheels of the own vehicle 2: Own vehicle Yaw rate 9: is the lateral speed of the own vehicle.

The front/rear wheel steering angle target value δ7 obtained by such calculation. aR is input to the front wheel steering device 4 or the rear wheel steering device 5, respectively, through the process of the next step 46.

The front wheel steering device 4 and the rear wheel steering device 5 adjust the front wheels 9, 1o or the rear wheels 11 to a given steering angle target value δF or δ.
, 1'2 is supplied to the hydraulic steering devices 6, 7, thereby steering the front wheels 9, 1'2.
10 and the rear wheels 11, 12 are steered.

In this manner, the device of this embodiment attempts to realize the motion performance of the target vehicle by controlling the wheel steering angle of the own vehicle.

The device of this embodiment responds to changes in road surface conditions by
Cornering power in vehicle specifications KFg 7
By correcting KRg and controlling the wheel steering angle through calculations using this correction value, it is possible to perform control in response to changes in road surface conditions as if tires with different characteristics (cornering power) were installed. I can do it. In other words, when driving on a rough road, the ground load of the tires fluctuates greatly due to vibration, but as mentioned above, by setting the cornering power of the vehicle's wheels to be lower than when driving on a good road, depending on the road surface condition, cornering Wheel steering angle control is performed assuming that tires with low power are installed.

As a result, even when driving on a rough road, the vehicle has substantially the same motion characteristics as when driving on a good road, and the driver can perform the same steering operations as when driving on a good road without worrying about changes in road surface conditions.

Although the above embodiment shows an example in which both the front wheels and the rear wheels are controlled, the present invention is applicable to a vehicle in which the front wheels are steered by a conventional mechanical link type steering device and only the rear wheels are electronically controlled. It can also be applied to

In this case, the rear wheel cornering power may be determined by calculation that takes into account changes in the front wheel cornering power.

(Effects of the Invention) As explained in detail above, the present invention assumes a target vehicle with desired motion performance, and controls the wheel steering angle of the own vehicle so as to realize the motion characteristics of the target vehicle. ,
It becomes possible to freely control the driving performance of the own vehicle.

In addition, by correcting the own vehicle specifications used in calculations for steering angle control in accordance with the road surface conditions so that the motion characteristics do not change due to changes in road surface conditions, the accuracy of achieving the target vehicle motion characteristics is improved. is not affected by changes in road surface conditions and always provides stable driving characteristics.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the present invention, Fig. 2 is a block diagram of an embodiment of the present invention, and Fig. 3 is a diagram showing the development of the front wheel steering device, rear wheel steering device, and hydraulic steering device in Fig. 2. , FIG. 4 is a block diagram showing a specific circuit example of the road surface condition detector shown in FIG. 2, and FIG. 5 is a flowchart showing the processing executed by the microcomputer shown in FIG. 2. 100...Handle steering amount detection means 101...Vehicle speed detection means 102...Motion variable target value calculation means 103...Wheel steering angle target value calculation means 104...Wheel steering means 105...Road surface condition,
Rough detection means 106...Vehicle specification correction means 1...Microcomputer 2...Handle steering amount sensor 3...Vehicle speed sensor 4...Front wheel steering device 5...Rear wheel steering device 6. 7...Hydraulic steering device 8...Steering handle 9.10...Front wheel 11.12...Rear wheel 18...Road surface condition detector Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] 1. Steering wheel steering amount detection means for detecting the steering amount of the steering wheel; vehicle speed detection means for detecting vehicle speed; and based on an equation of motion regarding a target vehicle having a preset target motion performance. a motion variable target value calculating means for calculating a target value of a motion variable corresponding to the steering amount of the steering wheel and the vehicle speed; wheel steering angle target value calculating means for calculating a target value of a wheel steering angle of at least one of the front wheels or the rear wheels to realize the motion variable target value; Wheel steering means for steering corresponding wheels, road surface condition detection means for detecting road surface conditions, and correcting the vehicle specifications of the own vehicle according to the road surface condition detected by the road surface condition detection means. 1. A steering angle control device for a vehicle, comprising: vehicle specification correction means.