JPS6215173A - Vehicle motion state quantity computing device - Google Patents

Abstract

PURPOSE:To make it possible to enhance the control accuracy of a vehicle steering system, by providing a compensating means for compensating a value corresponding to a cornering power in accordance with a detected displacement of a suspension so that the quantity of motion state may be obtained corresponding to a change in cornering power. CONSTITUTION:Suspension stroke sensors 13 through 16 for detecting the displacements of suspensions provided respectively to front and rear wheels 9 through 12, are attached to the suspensions, and the displacements of the suspensions are delivered to a computing and processing device 1. Further, a cornering power compensation is made such that the cornering powers KF, KR of front and rear wheels of vehicle dimensions of the instant vehicle are compensated in accordance with the pitching and rolling of a vehicle body. A desired rear wheel steering angle value delta'R which is computed is delivered to a rear wheel steering device 5 which feeds hydraulic pressure into a hydraulic steering device 7 such that the steering angle of the rear wheel is made to be equal to the desired value delta'R.

Description

[Detailed Description of the Invention] (Industrial Application) This invention calculates the vehicle motion state quantity by calculation, and uses the obtained motion state quantity for various controls (for example, control of the steering system, etc.) The present invention relates to a vehicle motion state quantity calculation device, and particularly relates to a vehicle motion state quantity calculation device that takes into account changes in cornering power when the vehicle rolls or the like.

(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.

On the other hand, the applicant of the present application previously filed a patent application filed in
No. 018, Japanese Patent Application No. 188153, 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, if this device is used, for example, even if the own vehicle is a sedan type vehicle, if the target vehicle is set as a sports car type vehicle, even if the vehicle body structure etc. is a sedan type vehicle, it will be a sports car type vehicle. Maintaining athletic performance, etc.
This allows you to freely control your 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, when controlling the steering angle of the wheels of the own vehicle, the above-mentioned device calculates the target value of the wheel steering angle necessary to achieve the target motion performance of the own vehicle by combining the motion variable target value and the steering angle of the vehicle. This is determined by a calculation using the vehicle specifications of the vehicle, and the wheels are steered in accordance with the target value of the wheel steering angle determined by this calculation.

However, since the vehicle specifications of the own vehicle used in the above calculation are fixed values (for example, each vehicle specification is set at the time of shipment of the vehicle), for example, when the vehicle is running, , rolling, pitching, etc., the cornering power of the tires, which is one of the vehicle specifications, fluctuates. For this reason, even if an attempt is made to achieve the target dynamic performance of the own vehicle through control using the fixed vehicle specifications, a control error will occur corresponding to the variation in the cornering power.

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

The vehicle motion state quantity calculation device 100 of the present invention calculates the motion state quantity of the vehicle by calculation using at least the vehicle specifications of the own vehicle and utilizes it for controlling various control devices [103]. Equipped with suspension displacement detection means 101 and vehicle specification correction means 102 ◇ The suspension displacement detection means 101 detects the displacement of the suspension at the front and rear of the vehicle body, and the vehicle specification correction means 102 detects the displacement of the suspension at the front and rear of the vehicle body. Corresponding to the detected suspension displacement ΔX, a value corresponding to the cornering power among the vehicle specifications of the host vehicle is corrected.

(Function) When the vehicle body rolls or pitches, displacement occurs in the front and rear suspensions of the vehicle body. Therefore, this suspension displacement ΔX is detected by the suspension displacement detection means 10.
1, and the vehicle specification correction means 102 corrects the value of cornering power among the vehicle specifications of the host vehicle in accordance with the suspension displacement ΔX. This results in
The amount of motion state corresponding to changes in the cornering power of the own vehicle due to rolling, pitching, etc. of the vehicle body is determined, improving control accuracy.

(Example) The configuration of one embodiment of the present invention is shown in FIG.

The arithmetic processing device 1 is configured by a microcomputer or other electric circuit, and calculates the steering angle θ8 of the steering wheel 8 detected by the steering wheel steering angle sensor 2.
Then, the vehicle speed V of the vehicle equipped with the device of this embodiment (hereinafter referred to as "own vehicle") detected by the vehicle speed sensor 3 is inputted, predetermined calculations are performed, and a rear wheel steering angle target value δR is output.

The front wheels 9,10 are steered to a steering angle corresponding to the amount of steering of the steering wheel 8 by a mechanically linked steering device 6 similar to that of conventional vehicles.

'1Mx1. ．． xg is 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. This rear wheel steering device! ! 5 changes the oil pressure applied to the hydraulic steering device 7 in accordance with the rear wheel steering angle target value δR inputted from the arithmetic processing device 1, so that the actual steering angle δR of the rear wheels 11 and 12 becomes the rear wheel steering angle. The hydraulic steering device 7 is controlled so that the target value δR is achieved (for details, see Japanese Patent Application No. 59-1881).
53).

In addition, suspension stroke sensors 13 to 1 for detecting all displacements of the suspension are installed on the suspensions provided on each of the front wheels 9, 10 and the rear wheels 11 and 12.
6 is installed, and the left front wheel suspension displacement ΔXFL detected by each suspension stroke sensor 18 to 16 'Right front wheel suspension displacement ΔX Left rear wheel suspension FR' Yon displacement ΔX Right rear wheel suspension displacement ΔxRR
RL% is input to the arithmetic processing device 1.

The suspension strike sensors 18 to 16 may be, for example, those that electrically detect the piston displacement of a shock absorber, those that detect suspension displacement using a potentiometer attached to the suspension, or those that use optical or ultrasonic media. This sensor uses any one of various known sensors, such as one using a sensor.

3 and 4 are flowcharts showing the processing executed by the arithmetic processing device 1 when the arithmetic processing bag g11 is configured using a microcomputer.

The steering angle control process shown in FIG. 8 is a control process for controlling the steering angles of the rear wheels 11 and 12 to achieve target driving performance in the own vehicle. Furthermore, the cornering power correction process shown in FIG. 4 is a process of correcting the front and rear wheel cornering power Ky and KRre of the vehicle specifications of the own vehicle in accordance with rolling, pitching, etc. of the vehicle body. is repeatedly executed every predetermined time period t,t.

In the process of step 21, the steering wheel steering angle θ8 and the vehicle speed V
is read, and in the process of step 22, the target values of the motion variables corresponding to the steering wheel angle θ8 and the vehicle speed V (in this example Then, calculations are performed to determine the target values for the yaw rate and yaw angular acceleration.

The target vehicle model is a vehicle having the above-mentioned target dynamic performance (for example, a desired dynamic performance such as improving responsiveness and stability of yaw rate changes), based on characteristic equations, motion equations, and vehicle specifications. This is a simulation model expressed by Yuan et al., and when the above-mentioned steering wheel angle θ8 and vehicle speed V are given, the above-mentioned motion variable target value is determined according to the target motion performance. Hereinafter, the target vehicle model will be simply referred to as "target vehicle"◇ The above-mentioned motion variable target values, that is, the yaw rate target value and the yaw angular acceleration target value, are obtained by the following calculations.

a, cv,,+÷,V) = za,+zaR,,・(
1) Engineering Zlψ, = 2 IIF engineering OF□-2LRIOR
E...(2) OR1=-KRl (vyl
-LR19), )/v"' (4) here, here, z□: Yaw inertia of the target vehicle Ml: Body mass of the target vehicle LF□: Distance between the front axle and the center of gravity of the target vehicle LR1'Target vehicle Distance between rear axle and center of gravity N0: Steering gear ratio of target vehicle KFl 'Cornering power of front wheels of target vehicle KR□
: Target vehicle's rear wheel cornering power ÷, : Target vehicle's yaw rate ψ, : Target vehicle's yaw angular acceleration ■A, : Target vehicle's speed in the y-axis direction V : Target vehicle's lateral periphery acceleration in the y-axis direction 0, □: Front wheel cornering force of the target vehicle CR □: Rear wheel cornering force of the target vehicle 〇 In the process of step 24, the yaw rate target value and yaw angular acceleration target value ψ obtained in the process of step 22 above are determined by the own vehicle. A calculation is performed to obtain the rear wheel steering angle target value δR necessary to achieve this. ◇The calculation of this rear wheel steering angle target value δR is as follows.
This was done using the above money and φ and the vehicle specifications of the own vehicle, and among the vehicle specifications of the own vehicle, the front and rear wheel cornering power was determined by the process shown in Figure 4. The cornering power correction values KF* and KR* are read in the process of step 23 and used in the calculation of δR.

The rear wheel steering angle target value δR is calculated according to the following formula.〇lK11'F! ”NmK3!(θB−N2δFz)−D
Kg 'Fja −”ξ, (3F, ・(7)
M, (y, +ψV) =2107. +2GRB
・”(8) β1rl=alrl−(7B+Ly2i
)/V...-(e)'Fg = Ky h*
−(10)OR1=(LFll
lCF! -29' Engineering Zl! )/LHg”
' (11) βRz = cRz/KX
−(1ri JR= βR2+ (72−LRfii
) / V - (18) Here, za 'Yaw inertia M of own vehicle: Vehicle weight of own vehicle: Wheelbase of own vehicle L12: Distance between front axle and center of gravity of own vehicle LRg' Own vehicle Distance 1 between the rear axle and the center of gravity, S' Inertia around the king pin of the own vehicle Ks, : Steering rigidity of the own vehicle DK, : Steering system viscosity coefficient ξ of the own vehicle, : Trail of the own vehicle N : Steering of the own vehicle Gear ratio δ1. : Front wheel steering angle of the own vehicle: Lateral speed y of the own vehicle, : Lateral acceleration β of the own vehicle : Side slip angle of the front wheels of the own vehicle βRz 'Side slip angle of the rear wheels of the own vehicle OF2: Side slip angle of the front wheels of the own vehicle Cornering force OR2: Cornering force of the rear wheels of the own vehicle.

The rear wheel steering angle target value δR obtained by the above calculation is supplied to the rear wheel steering device 5. ．． Necessary hydraulic pressure is supplied to the hydraulic steering device 7 so that the steering angles of la are equal. As a result, the rear wheel 11.1
2 steering is performed.

Therefore, the target driving performance will be achieved by controlling the rear wheel steering angle. Also, due to rolling and pitching of the car body, the actual tire cornering power By detecting this fluctuation and correcting the values of front and rear wheel cornering power used to calculate the rear wheel steering angle target value δR, the accuracy of achieving the target driving performance will change. There's nothing to do.

Correcting the values of the front and rear wheel cornering powers used in the calculation in response to the fluctuations in the actual tire cornering power is performed by the cornering power correction process shown in FIG. 4, as described above.

In the process of step 31, the detection value ΔxFL −ΔxFR of each of the suspension stroke sensors 18 to 16,
A process of reading ΔxRL−ΔxRR is performed.

In the process of step 32, each of the detected values ΔxFL to ΔX is selected from a data table stored in the memory in advance.
The value of the cornering power of each wheel corresponding to RR (this is referred to as the "estimated cornering power value") KFL,
Find KFR, KRL, and KRR. Here, K: Left front wheel cornering power estimated value L KFR' Right front wheel cornering power estimated value KRL' Left rear wheel cornering power estimated value K: Right rear wheel cornering power estimated value R.

These KFL to KRR data tables include, for example,
According to the characteristics shown in Fig. 7, KFL ”= ”RR
data is stored.

The actual cornering power of each wheel is not uniformly determined with respect to the suspension stroke ΔX. This is because the tire toe angle θ and the camber angle θC change as the suspension stroke ΔX changes.

The camber angle θC and the tire toe angle θT are expressed as a univariate function of the suspension stroke ΔX, as shown in FIGS. 5 and 6.

Therefore, the relationship between the cornering power and suspension stroke of each wheel (the relationship shown in Figure 7) can be determined by measuring the actual cornering power at multiple suspension stroke values through experiments in advance, and storing this experimental data in memory. If stored as a data table, it is possible to estimate a value of cornering power that is extremely close to the value during actual driving.

In this way, the estimated cornering power value KFL''KRR for each wheel obtained from the suspension stroke for each wheel can be estimated to be the actual cornering power of the own vehicle at that time.

In the next step 33, from the estimated cornering power value KFL ""' KRR obtained as described above,
For each of the front wheels and the rear wheels, the front wheel cornering power correction value KF* and the rear wheel cornering power correction value KR are determined by taking the average of the estimated cornering power values of the left and right wheels. These x, *, xR* are used to calculate the rear wheel steering angle target value δR mentioned above.
The above-mentioned effects can be obtained.

In addition, in the above embodiment, an example was shown in which the present invention is applied to a device that controls the steering system of a vehicle and freely controls the motion performance of the vehicle. (For example, a device that calculates the yaw left and sideslip angle corresponding to the vehicle speed and steering angle based on the vehicle specifications of the own vehicle and controls the power steering hydraulic pressure, and the device that controls the movement of the vehicle. It is also applicable to driving force control devices, etc.).

(Effects of the Invention) As described in detail above, the present invention detects changes in cornering power of wheels based on suspension displacement, and detects changes in cornering power of the own vehicle based on the displacement of the suspension. By correcting the value equivalent to the cornering power in It is possible to correct the value of

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention; FIG. 2 is a block diagram of an embodiment of the present invention; FIGS. Figure 5 is a relationship diagram between suspension stroke and camber angle in a vehicle, Figure 6 is a relationship diagram between suspension stroke and tire toe angle in a vehicle, and Figure 7 is a data table of cornering power provided in the embodiment shown in Figure 2. FIG. 100...Vehicle motion state quantity calculation device 101...Suspension displacement detection means 102...
Vehicle specification correction means l...Arithmetic processing unit 2...Hand #mJ+'l sensor 8...Vehicle speed sensor 5...Rear wheel steering device? ...Hydraulic steering device 9.10...Front wheels 11, 12...Rear wheels 13-16...Suspension stroke sensor ΔX
...Suspension stroke ΔxFL...Left front wheel suspension displacement ΔxFR...
・Right front 1 suspension displacement ΔxRL...Left rear wheel suspension displacement ΔXRR...Right rear wheel suspension displacement KF*...Front wheel cornering power correction value KR*.
... Rear wheel cornering power correction value δR ... Rear wheel steering angle target value (dynamic state quantity) Patent applicant Nissan Motor Co., Ltd. Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. In a vehicle motion state quantity calculation device that calculates the motion state quantity of the vehicle by calculation using at least the vehicle specifications of the own vehicle and uses it for various controls, the displacement of the front and rear suspension of the vehicle body is calculated. and a vehicle specification correction means for correcting a value corresponding to cornering power among the vehicle specifications of the host vehicle in response to the detected suspension displacement. Vehicle motion state quantity calculation device.