JPH0211474A - Actual angle control device for vehicle - Google Patents

Abstract

PURPOSE:To provide desired vehicle dynamic characteristics coinciding to the movement target value of a normative model by a method wherein feedback is made on a vehicle output actual value being a control result and an actual steering target value is corrected so that the vehicle output actual value coincides to a vehicle output estimating value. CONSTITUTION:Based on a steering angle and a car speed detected by a steering angle detecting means (a) and a car speed detecting means (b), respectively, the one actual steering target value of front and rear wheels is calculated by an actual steering angle calculating part (c). The one actual angle of front and rear wheels is controlled by a actual steering angle control part (d). An actual steering angle calculating part (c) calculates an actual steering angle target value so that a vehicle movement estimating value by an estimating model (f) coincides with a vehicle movement target value based on a normative model (e), a steering angle theta, and a car speed (v). In this device, a vehicle output actual value is detected by a vehicle output actual value detecting means (g). Based on the vehicle output actual value and a vehicle output estimating value, an actual steering angle correction value is calculated by an actual steering angle correction value calculating part (h). Based on an actual steering angle correction value and an actual angle target value, a final actual angle target value is calculated by a final actual steering angle calculating part (i).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a practical application for a vehicle that controls the steering angle of at least one of the front wheels or the rear wheels so as to obtain vehicle dynamic characteristics that are easy for the driver to control during steering. This invention relates to a steering angle control device.

(Prior art) Conventionally, as an actual steering angle control device for a vehicle, for example,
A device described in Japanese Patent No. 2-241769 is known.

The above conventional device includes a steering angle detection means, a vehicle speed detection means,
an actual steering angle calculating section that calculates an actual steering angle target value of at least one of the front wheels or the rear wheels by inputting the signals from the two detection means; and an actual steering angle calculating section that calculates an actual steering angle target value of at least one of the front wheels or the rear wheels; and an actual steering angle control section that controls the steering angle.

The actual steering angle calculation section has a reference model that models desired dynamic characteristics and an estimation model that models the dynamic characteristics of the own vehicle. The actual steering angle target value is calculated in order to obtain a response in which the vehicle motion estimated value based on the estimation model matches or follows the vehicle motion target value set based on.

(Problem to be Solved by the Invention) However, in such a conventional actual steering angle control device for a vehicle, the transfer characteristics of the estimated model given in advance almost match the transfer characteristics of the vehicle to be controlled. However, as shown in Figure 6, the transfer characteristic (solid line) of the estimated model given in advance is not the same as the transfer characteristic (solid line) of the vehicle to be controlled.
If they do not match the actual vehicle output value (dotted line), as shown in Fig. There is a problem in that the vehicle dynamic characteristics become larger, the vehicle deviates from the motion target value of the reference model, and desired vehicle dynamic characteristics cannot be obtained.

Therefore, one way to solve this problem, that is, to match the transfer characteristics of the estimated model with the transfer characteristics of the vehicle, is to increase the order of the estimated model.

However, in this case, there are problems described below.

■ As the order increases, calculations become more complex, and the burden on the computer used for control increases.
cannot be made small enough.

■ Even if the order of the estimated model is increased, if the parameters of the estimated model change due to changes in rainfall or road friction coefficient,
After all, there will be a difference between the transfer characteristics of the estimated model and the transfer characteristics of the vehicle.

The present invention was made with a focus on the above-mentioned problems, and even if there is a difference between the transfer characteristics of the estimated model and the transfer characteristics of the vehicle, the calculation load is small and it is not affected by changes in driving conditions. The objective is to develop an actual steering angle control system for a vehicle that can obtain desired vehicle dynamic characteristics that match or follow the motion target values of the reference model.

(Means for Solving the Problems) In order to solve the above problems, the actual steering angle control device for a vehicle of the present invention deals with the control error caused by the difference between the transfer characteristics of the estimated model and the transfer characteristics of the vehicle. This means that the difference between the estimated vehicle output value and the actual vehicle output value obtained by detection is fed back to the actual steering angle target value.

That is, as shown in the complaint correspondence diagram of FIG. 1, if the steering angle detecting means a and the vehicle speed detecting means are
The actual steering angle target value δ of at least one of the front wheels or the rear wheels is input by inputting a signal from the steering wheel. An actual steering angle calculation unit C that calculates the actual steering angle calculation unit C, and an actual steering angle control unit d that controls the actual steering angle 6 of at least one of the front wheels or the rear wheels corresponding to the actual steering angle calculation unit C,
The actual steering angle calculation unit C has a reference model e that models desired dynamic characteristics and an estimated model f that models the dynamic characteristics of the own vehicle, and calculates the actual steering angle based on the reference model e, the steering angle θ, and the vehicle speed V. The actual steering angle target value δ is set in order to obtain a response in which the vehicle motion estimated value by the estimation model matches or follows the set vehicle motion target value. The actual steering angle control device for a vehicle is provided with a vehicle output actual value detection means 9 for detecting a vehicle output actual value M which is an actual value of vehicle motion corresponding to the vehicle motion target value, Between the calculation section C and the actual steering angle control section d, the actual steering angle is calculated by comparing the actual vehicle output value M from the vehicle output actual value detection means 9 and the estimated vehicle output value M from the estimation model f. Angle correction value 6. the actual steering angle correction value calculation section 1, and the actual steering angle target value δ from the actual steering angle correction value 1 and the actual steering angle calculation section C.

The means is characterized in that it is provided with a final actual steering angle calculation section i which outputs the final actual steering angle target value δ* calculated by the following to an actual steering angle control section d.

Note that the vehicle motion value and vehicle output value refer to vehicle yaw rate, vehicle lateral acceleration, a combined value of yaw rate and lateral acceleration, and the like.

In addition, the actual steering angle correction value calculation unit and the final actual steering angle calculation unit i are calculated as follows: δ*=6°+6+” 50 + K (＾−M)6*
: Final actual steering angle target value 6 o : Actual steering angle target value ; Actual steering angle correction value K Nigain △ M : Estimated vehicle output value M : Actual vehicle output value The final actual steering angle target value δ* is determined by the relational expression: This is the calculation part.

(Function) When the transfer characteristics of the estimated model given in advance do not match the transfer characteristics of the vehicle to be controlled, the rear wheel steering angle correction value calculation section calculates the output from the vehicle output actual value detection means 9. Estimated vehicle output value M from the actual vehicle output value M and the estimated model f
An actual steering angle correction value δ is calculated by comparing the actual steering angle correction value δ1 with the actual steering angle target value δ from the actual steering angle calculation unit C in the final actual steering angle calculation unit l. A final actual steering angle target value δ* is calculated, and the final actual steering angle target value δ* is output to the actual steering angle control section d.

That is, the actual vehicle output value M, which is the control result, is fed back, and the rear wheel steering angle target value δ8 is corrected so that the actual vehicle output value M matches the estimated vehicle output value.

Therefore, even if there is a difference between the transfer characteristics of the estimated model f and the transfer characteristics of the vehicle, it is desirable to match or follow the motion target value of the reference model e with a small computational burden and without being affected by changes in the driving situation. vehicle dynamic characteristics can be obtained.

(Example) Embodiments of the present invention will be described below based on the drawings.

This embodiment is a rear wheel steering angle control device for a vehicle that uses yaw rate model adaptive control to set a desired yaw rate response model (normative model) and adjust the steering angle of the rear wheels so that the response of the vehicle matches the model. It is.

First, the configuration will be explained.

FIG. 2 is a diagram showing a vehicle to which the vehicle rear wheel steering angle control device of the embodiment is applied, in which 1 is a steering wheel, 2 is a steering shaft, 3 is a front steering gear unit, and 4 is a diagram showing a vehicle to which the rear wheel steering angle control device for a vehicle is applied.
．． 5 is the front wheel, 6 is the rear steering cylinder, 7, 8
are rear wheels, the front wheels 4.5 are steered by operating the handle 1, and the rear wheels 7.8 are steered by controlling the hydraulic pressure supplied from the hydraulic source 9.

The vehicle rear wheel steering angle control device that controls the steering angle of the rear wheels 7 and 8 includes a steering angle sensor 10 (
steering angle detection means), vehicle speed sensor 11 (vehicle speed detection means),
A yaw rate sensor 12 (vehicle output actual value detection means) is provided, and as an electronic control circuit, a rear wheel steering angle control unit 13 (actual steering angle calculation unit,
(including an actual steering angle correction value calculation section and a final actual steering angle calculation section), and a rear wheel steering control valve 14 is provided as an output member.

Incidentally, the rear steering cylinder 6, the hydraulic power source 9, and the rear wheel steering control valve 14 constitute an actual steering angle control section in the claims.

FIG. 3 is a block diagram of the rear wheel steering angle control unit 13, which has a reference model 131 modeling desired dynamic characteristics and an estimation model 132 modeling the dynamic characteristics of the own vehicle. The rear wheel steering angle target value δ is set in order to obtain a response in which the vehicle motion estimated value △ △ +p, Vy by the estimation model 132 matches the vehicle motion target value Y, which is set based on the steering angle 0 and the vehicle speed V.
The rear wheel steering angle calculation unit 13a calculates the rear wheel steering angle by comparing the yaw rate ψ (actual vehicle output value) from the yaw rate sensor 12 and the yaw rate estimate △ constant value ψ (estimated vehicle output value) from the estimation model 132. The rear wheel steering angle correction value calculation unit 13b calculates the steering angle correction value δ88, and the final rear wheel steering angle is determined by the rear wheel steering angle correction value δR8 and the rear wheel steering angle target value 68 from the rear wheel steering angle calculation unit 13a. Angle target value 8*
A final rear wheel steering angle calculating section 13c is provided to calculate the final rear wheel steering angle.

It should be noted that the vehicle 5 equipped with the vehicle rear wheel steering angle control device of the embodiment is influenced by the rear wheel steering angle according to the front wheel steering angle θ and the final rear wheel steering angle target value * during steering. A predetermined yaw rate φ is generated.

Next, the effect will be explained.

First, in the reference model 131, a vehicle motion target value Y is calculated using the following transfer characteristic.

Here, G (V) is a gain given in advance according to the vehicle speed V, T is a time constant given in advance, S is a Laplace operator, and θ is a front wheel steering angle.

Next, the estimation model 132 calculates estimated vehicle motion values ψ and Vy of the own vehicle by calculation based on the following state equation.

Here, a + 1= -2 (F to LF'+R to LR')/IZ
'(1/V)a + 2 = -2(LFKF-LR
KR)/IZ ・(+,/V)a 21= -2(Lp
Kp-LR to R)/u・(+/V) −vay2=−2
C to +R)/V・(+/V)b , , = 2L
, /I7・Nb ,, = -21, KR/I2 b 21 = 2 to F/IJN b22 = 2 to R/M If the above equations ① and ② are respectively converted into a state equation and an output equation, Yr = Ar- Yr + Br・θ・
・・■゛However, △ △ Xp = (*, Vy) Ar=-1/T
Or = G(V)/T.

Next, the rear wheel steering angle calculation unit 13a calculates a rear wheel steering angle target value δ8 based on the vehicle motion mouth target value Y and the estimated vehicle motion values ψ and Vy.

Here, ni1=(ni1.ni12), K2. In 3, by the expanded system for the step response, solve the Rikkatuchi equation % formula % for pH, then A+TP+2+PzA2 +P12ARPzB+RB
By the solution Pi of ITP+2=0...■, (KIK2) =-R-'B,"P,,
...■ to 3=-R-'B, TP, 2
...■ is the optimum gain (Japanese Patent Application Laid-Open No. 62-2
41769).

Next, the rear wheel steering angle correction value calculation unit 13b inputs the yaw rate ψ from the yaw rate sensor 2 and the yaw rate estimated value ψ from the estimation model is calculated.

△ 6R8=. (ψ-φ)...■Here, Ko is a predetermined gain; however, e=Yp-Yr...[phase] However, al is a real number.

Next, the final rear wheel steering angle calculating section 13c calculates the final rear wheel steering angle target value by using the rear wheel steering angle correction value δ, 8 and the rear wheel steering angle target value δ8 from the rear wheel steering angle calculating section 13a. δ8* is calculated using the following formula.

69*=688+68 ...■ Therefore, as shown in Fig. 4, the transfer characteristic (solid line) of the estimated model given in advance is the transfer characteristic (dotted line) of the vehicle to be controlled.
If they do not match, the rear wheel steering angle correction value calculation unit 13
In b, the rear wheel steering angle correction value δ□8 is calculated using the above formula 0 based on the difference between the estimated yaw rate ψ of the estimation model 1△32 and the yaw rate φ obtained by detection.
is calculated, and further, the final rear wheel steering angle calculating section 13c calculates the final rear wheel steering angle using this rear wheel steering angle correction value B and the rear wheel steering angle target value 68 from the rear wheel steering angle calculating section 13a. Target value δ8
* is calculated using the above formula 0.

That is, the yaw rate ψ, which is the control result, is fed into the feed chain, and the rear wheel steering angle target value 6R is corrected so that the yaw rate ψ matches the estimated yaw rate value ψ.

As a result of the above, as shown in Fig. 5, the yaw rate characteristic (solid line) of the reference model that provides the target value of vehicle motion and the yaw rate characteristic (dotted line) of the vehicle obtained as a control result almost match, and the desired value is achieved during steering. Vehicle yaw rate characteristics can be obtained.

As explained above, in the vehicle rear wheel steering angle control device of the embodiment, a desired vehicle yaw rate characteristic matching the yaw rate movement target value of the reference model 131 can be obtained, and
The following effects can be achieved together.

■ Unlike the method of increasing the order of the estimation model, there is no computation complexity associated with increasing the order, so the burden on the computer used for control is small, and the computation increments (control period) are small enough to avoid response delays. You can take it.

■ Since the rear wheel steering angle target value 6R is corrected and controlled by feedback of the vehicle's yaw rate φ, which is a control result that includes all driving condition elements such as rainfall and changes in the road surface friction coefficient, the preset value is The vehicle's transfer characteristics are made to match the estimated model's transfer characteristics not only when there is a difference between the transfer characteristics of the estimated model 132 and the vehicle to be controlled, but also when there is a change in rainfall or road friction coefficient. Be responsive.

Although the embodiment has been described above based on the drawings, the specific configuration is not limited to this embodiment. include.

For example, in the embodiment, a device that controls the steering angle of the rear wheels is shown, but the present invention can also be applied to a four-wheel steering vehicle that controls the steering angle of both the front and rear wheels.

Further, although an example of control has been shown in which the dynamic characteristics of the vehicle are viewed using the yaw rate, it is of course possible to view the dynamic characteristics of the vehicle using the lateral acceleration or a linear combination of the yaw rate and the lateral acceleration.

(Effects of the Invention) As explained above, in the vehicle actual steering angle control device of the present invention, the vehicle output that detects the actual vehicle output value which is the actual value of the vehicle motion corresponding to the vehicle motion target value Actual value detection means is provided between the actual steering angle calculation section and the actual steering angle control section. An actual steering angle correction value calculation section that calculates a steering angle correction value, and a final actual steering angle target value calculated using the actual steering angle correction value and an actual steering angle target value from the actual steering angle calculation section, are used for actual steering angle control. Since a final actual steering angle calculation unit is provided, even if there is a difference between the estimated model's transmission characteristics and the vehicle's transmission characteristics, the calculation load is small and the standard is not affected by changes in driving conditions. The effect is that it is possible to obtain desired vehicle dynamic characteristics that match or follow the motion target values of the model.

[Brief explanation of the drawing]

FIG. 1 is a claim-corresponding diagram showing an actual steering angle control device for a vehicle according to the present invention, FIG. 2 is an overall view showing a vehicle to which the rear wheel steering angle control device for a vehicle according to an embodiment of the present invention is applied, and FIG. A block diagram showing the rear wheel steering angle control unit of the vehicle rear wheel steering angle control device of the embodiment, FIG. 4 is a diagram showing the transfer characteristics of different estimation models and the transfer characteristics of the vehicle, and FIG. 5 is the embodiment device A comparison diagram of the yaw rate characteristics of the reference model and the yaw rate characteristics of the vehicle, Figure 6 is a diagram showing the transfer characteristics of the different estimated models and the transmission characteristics of the vehicle, and Figure 7 is the yaw rate characteristic of the reference model with the conventional device. FIG. 2 is a comparison diagram of the yaw rate characteristics of the vehicle and the yaw rate characteristics of the vehicle. a...Steering angle detection means b...Vehicle speed detection means C...Actual steering angle calculation section d...Actual steering angle control section e...Reference model f...Estimation model 9...-Vehicle Output actual value detection means h...Actual steering angle correction value calculation unit i...Final actual steering angle calculation unit

Claims (1)

[Scope of Claims] 1) Steering angle detection means, vehicle speed detection means, and actual steering angle calculation that calculates an actual steering angle target value of at least one of the front wheels or the rear wheels by inputting signals from both of the detection means. and an actual steering angle control unit that controls an actual steering angle of at least one of a front wheel or a rear wheel corresponding to the actual steering angle calculation unit, the actual steering angle calculation unit modeling desired dynamic characteristics. It has a reference model based on the model, and an estimation model that models the dynamic characteristics of the own vehicle, and the vehicle movement estimated value by the estimation model matches or follows the vehicle movement target value set based on the reference model, steering angle, and vehicle speed. In a vehicle actual steering angle control device in which an actual steering angle target value is calculated to obtain a response, the vehicle output actual value detection means detects a vehicle output actual value that is an actual value of vehicle motion corresponding to the vehicle motion target value. is provided between the actual steering angle calculation section and the actual steering angle control section, and a controller that calculates the actual steering angle by comparing the actual vehicle output value from the actual vehicle output value detection means and the estimated vehicle output value from the estimation model. An actual steering angle correction value calculation section that calculates an angle correction value, and an actual steering angle control section that calculates the final actual steering angle target value calculated using the actual steering angle correction value and the actual steering angle target value from the actual steering angle calculation section. An actual steering angle control device for a vehicle, characterized in that it is provided with a final actual steering angle calculation section that outputs an output to the actual steering angle. 2) The actual steering angle control device for a vehicle according to claim 1, wherein the vehicle output value is a vehicle yaw rate, and the vehicle motion target value and the vehicle motion estimated value are a motion target value and a motion estimated value of the yaw rate. 3) The actual steering angle correction section and the final actual steering angle calculation section calculate δ^*
= δ_0 + δ_1 = δ_0 + K (■ - M) δ^*; Final actual steering angle target value δ_0; Actual steering angle target value δ_1; Actual steering angle correction value K; Gain ■; Vehicle output estimated value M; Vehicle output actual value 2. The actual steering angle control device for a vehicle according to claim 1, wherein the part calculates the final actual steering angle target value δ^* using the formula.