JPS62149562A - Steering angle control device for vehicle - Google Patents

Abstract

PURPOSE:To compensate the delay in response of an actuator steering wheels, by providing a steering angle deviation calculating means which determines a deviation between the actual steering angle and the steering angle desired value of a wheel to be controlled. CONSTITUTION:Steering of rear wheels 48 and 49 is effected by a hydraulic cylinder 40, and a difference in an oil pressure between hydraulic chambers 41 and 42 is controlled by a control valve 50. Signals from a car speed sensor 20, a handle steering angle sensor 21, a handle steering angle sensor 22, a stroke sensor 23, and a displacement speed sensor 24 are inputted to a control circuit 30 controlling the valve 50, an a current desired value (i) is outputted to a current controller 38 from the circuit 30. In the circuit 30, a deviation IB between a rear wheel steering angle speed desired value deltaR0' and a detecting value deltaR0 of a rear wheel actual steering angle speed is determined by a deducting part 34, steering of rear wheels is effected until the deviation is reduced to zero to compensate a delay in response, and maneuverability during high speed running is pevented from lowering.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a steering angle control device for a vehicle that controls a heavy wheel steering angle of a vehicle according to a preset maneuverability nth. In particular, the present invention relates to a vehicle steering angle control device that compensates for response delays of actuators that steer wheels.

(Prior Art) Conventionally, it has been possible to control the dynamic performance of a vehicle by steering the wheels using actuators that are driven and controlled by an electrical control circuit, without using a mechanical link with a steering wheel. A device has been proposed (for example, there is one shown in Japanese Patent Laid-Open No. 143772/1983).

This conventional device determines the target value of the steering angle of the front and rear wheels corresponding to the steering angle of the steering wheel according to a preset control law, and uses a servo actuator using a hydraulic cylinder to control the front and rear wheels. The steering angle is steered to the above-mentioned target steering angle value.

(Problems to be Solved by the Invention) However, since the actuator described above is generally a linearly coupled system that performs integral action, the control response is delayed, which is a factor that reduces maneuverability during high-speed driving. Become.

Therefore, it is possible to eliminate the above delay by applying differential □ compensation to the control system of the actuator.

However, when determining the target steering angle value using a digital circuit such as a microcomputer, the signal to which the differential compensation is applied is a digital signal.
If you look at this signal microscopically, it has a step-like shape, so if you differentiate this signal using a normal differentiator circuit, you will end up with a discrete differential value signal, making the control inaccurate. Become.

In other words, in a control system using digital circuits,
It is difficult to perform differential compensation using a differential circuit.

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

The steering angle target value determining means 108 controls/controls at least one of the front wheels or the rear wheels corresponding to the steering angle θS of the steering wheel detected by the steering angle detecting means 100 and the single series V detected by the vehicle speed detecting means 102. A target value δ of the steering angle of the target wheel is determined according to a preset target motion performance.

The steering angular velocity target value determining means 104 determines the target value δ of the steering angular velocity of the wheel to be controlled corresponding to the steering angular velocity θS of the steering wheel detected by the steering angular velocity detecting means 101 and the vehicle speed . Determine according to exercise performance.

The steering angle deviation calculation means 107 calculates a deviation A between the actual steering angle δ of the control target wheel detected by the actual steering angle detection means 105 and the steering angle target value δ.

The steering angular speed deviation calculating means 108 is the actual steering angular speed detecting means 1.
The deviation between the actual steering angular velocity δ of the control target wheel detected in step 06 and the target steering angular velocity value δ is determined.

The wheel steering means 1θ9 steers the wheels to be controlled so that both the deviations IA and IB become zero or minimum.

(Operation) Is the deviation IA calculated by the steering angle deviation calculation means 107? By steering the wheels to be controlled so that the steering angle becomes zero or the minimum, the wheel steering angle is controlled so that the target driving performance is achieved by the own vehicle.

Furthermore, by steering the wheels to be controlled so as to make the deviation 8 calculated by the steering angular velocity deviation calculating means 108 zero or minimum, the wheels can be turned so as to capture the response delay in the wheel steering means 109. Since the rudder speed can be controlled, differential compensation can be performed without using a differential circuit.

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

In this embodiment, the steering angles of both rear wheels 48 and 49 are controlled,
The aim is to achieve the target exercise performance. The front wheels (not shown) are steered by a mechanical link with a steering wheel (not shown), similar to the conventional Kameoka.

Rear wheel 48.490 steering is performed by a hydraulic cylinder 40. This hydraulic cylinder 40 has two hydraulic chambers 4 on the left and right.
1.42, and working hydraulic pressure is supplied to these hydraulic chambers 41.42 via oil passages 54, 55.

- The oil pressure difference between the two front pressure chambers 41, 42 is controlled by the control valve 50, and the piston rod 45 is displaced in response to this oil pressure difference. This displacement of the piston rod 45 is transmitted to the knuckle arms 46.47 to steer the rear wheels 48.49. Note that 52 is an oil pump and 53 is a reservoir. Further, 48.44 is a return spring.

The hydraulic cylinder 40 is controlled by controlling the control pulp 50 with the control circuit 80.

The control circuit 80 is a digital control circuit composed of a microcomputer or other digital circuit.

In the figure, the configuration of the control circuit 30 is shown in a block diagram for easy understanding.

The data input to this control circuit 80 is the vehicle speed sensor 2
0, the steering angle θ8 of the steering wheel detected by the steering wheel angle sensor 21, the steering angular velocity θS of the steering wheel detected by the handheld steering angular velocity sensor z2, and the steering angle θS detected by the stroke sensor 2B. actual steering angle δR1 and displacement speed sensor 24
This is the rear wheel actual steering angular velocity δR detected at . Further, the control circuit 80 outputs current port +*i direct 1 to the current controller 38.

The steering wheel steering angular velocity sensor 22 is configured, for example, by attaching a rate gyro to the steering wheel to obtain a signal corresponding to the rotational speed of the steering wheel.

The stroke sensor 28 actually detects the amount of displacement of the piston rod 45, but since the amount of displacement of the piston rod 45 has a correlation with the actual steering angle of the rear wheels 48 degrees 49, this stroke The detection signal of the sensor 2B can be regarded as a detection signal of the rear/actual steering angle. Similarly,
The detection signal of the displacement speed sensor 24 can be regarded as a detection signal of the rear wheel actual steering angular velocity.

The control circuit 80 includes a steering angle target value determination unit 81 that determines a rear wheel steering angle target value δ□ corresponding to the steering angle θS and the vehicle speed V according to a preset target motion performance, and a steering angle target value determination unit 81 that determines a rear wheel steering angle target value δ□ corresponding to the steering angle θS and the vehicle speed V.
The vehicle includes a steering angular speed target value determining section 82 that determines a rear wheel/steering angular speed target value δR corresponding to S and vehicle speed V in accordance with the above-mentioned target motion performance.

The input/output transfer characteristic between the steering angle θS and the rear wheel steering angle target value δR of the steering angle target value determining unit 81 and the steering angular speed θS and the rear wheel steering angle speed target value δR of the steering angle speed target value determining unit 82. The input/output transfer characteristics between them are the same transfer characteristic G(8).

The steering angle target value determining section 81 and the steering angle speed target value determining section 82
are each a mathematical model (hereinafter referred to as "
A mathematical model for simulating the motion of the own vehicle (hereinafter referred to as the "target vehicle model")
It is equipped with

The pilot car model is constructed using the vehicle specifications of the own army.

The steering angle target value determination unit 31 uses the target vehicle model to determine the yaw rate and yaw angular acceleration exhibited by the vehicle model when the steering angle θS and vehicle speed V are given, and determines these as a yaw rate target value set.

The rear wheel steering angle (rear wheel steering angle target value δR) required to make the yaw rate and yaw angular acceleration of the own vehicle equal to or equal to each other is determined by applying it to the own army model.

Specifically, the above-mentioned yaw rate target value and yaw angular acceleration target value are determined by the equation shown below.

ul(v,,+÷□V) = 2 CFl + 2C
R1・++ fl) engineering, □≠1””’FICF knee 2L
RICR□ ... (2) βR1" - (vyl
"R1 meeting,) /V - (4+CF+ =
KFt・βF ・“°(5)
CR work” KR work/βR work...
・(6) ψ = ψ,
...(7) ψ=ψl
...(8)・Here, Engineering 2□: Yaw inertia of the target direct-vehicle model M1: Electric mass of the target vehicle model LF□: Distance between the front axle and the center of gravity of the target heavy-duty model LR□:
Distance between the rear axle and center of the target East model KF: Cornering torque of the front wheels of the target vehicle model , yaw angular acceleration Vy of the two-eye leaning vehicle model: lateral velocity Ω7 of the target vehicle model, lateral acceleration βFl of the two-target Kameoka model Side slip angle βR of the front wheels of the target vehicle model: behind the target leaning vehicle Wheel sideslip angle OF: Cornering force CR of the front wheels of the target vehicle model = Cornering force of the rear wheels of the target vehicle model.The rear wheel steering angle target value δR is obtained by the calculation shown below.

2δF2 = N2KS2 (θS '2δF2
)-DK22F□-2ξ2C72...(9)N2(V
, +911V) = 2CF2+2CR2-(10)
βF2 ”δF2- (V, + LF2÷)/V
−(11)OF2 = KF2βF2
...(12)GRz” (LF
gCFg−1ψIZ2)/LR2・” (13) β
R2=OR2/KR2...(14) δR=βR,+
(vy2 LR2'/ )/V"・
(15) Here, engineering z2: Yaw inertia of own vehicle model N2: Vehicle weight of own vehicle model L2: Wheelbase of own 11tE model LF2 ``Distance between front axle of own model and change of center LR2'' Rear axle of own force model and the distance between the center of gravity 2: Inertia around the king pin of the vertical model 82: Steering stiffness of own vehicle model DK2: Steering system viscosity coefficient ξ2 of own army model: Trail of own vehicle model N2: Steering of own army model Gear ratio δF2" Front wheel steering angle of own vehicle model Vy2: Lateral speed V of own army model: Lateral acceleration β of own vehicle model, 2: Side slip angle of front wheels of own army model βR2" Side slip angle of rear wheels of own army model CF2 ``Cornering force C of the @wheels of the own army model: Cornering force of the rear wheels of the Naoki model KF2: Cornering power of the front wheels of the own vehicle model KR2: Cornering power of the rear wheels of the own army model.

Further, the steering angular speed target value determination capital 82 uses the target vehicle model and the own army model to calculate the rear wheel steering angle corresponding to the first differential value of the rear wheel steering angle target value δR from the steering angular speed θS and heavy speed V. Determine the angular velocity target value δR. This rear wheel steering angular velocity target value δR is determined by a calculation in which the motion variables in equations (1) to (15) for calculating the rear wheel steering angle target value δR are replaced with respective first-order differential values. That is, δR is determined by the following calculation.

M(V +9)V)=26F, +2OR□-(1
6) 1 yl 1 engineering, □ψ□” 2 LFI 6y knee 2”R1”R1・
...(17)6Fl ”KFl・βFl
-(20) 6R work = KR work / β□□
...(21) ψ=ψ□
°−(22)ψ=ψ, −°°(2B) 2′F2 ” N2KS2 'S−'2δF2)−
DK22F□−2ξ2 ”F2 °−(24)M
(V +9)V) = 26F2+2('3.
-・-(25) y2 7F2 = bite (v,, + LF29')/V
−(16)aF2 = KF2βF2
- (27) aRz = ("F2"F2-1ψIz2)/LR2... (28) Back R2 = "R2/
KR2° - (29) (The number of dots placed above each fWi indicates the order of differentiation) The above equations (16) to (28) are calculations performed using the eye $ vehicle model, and the equation (24 ) to (80) are calculations performed using the own vehicle model.

In the control circuit 80, a subtraction unit 83 calculates the deviation A between the rear wheel steering angle target value δR and the detected value δ of the rear wheel actual steering angle, and a subtraction unit 84 calculates the rear wheel steering angular speed target value. .

Furthermore, in the control circuit 80, after giving gains and KD to the above-mentioned deviation A and deviation 8, they are added to form a current target value 1.

The current controller 88 generates an exciting current 1 to be applied to the solenoid 51 of the control pulp 50 in response to the current target value 1 applied from the control circuit 80 .

The rear wheels 48.49 are steered until the differential 3 becomes zero.

Through such control, the response delay when the hydraulic cylinder 40 steers the rear wheels 48,49 to the rear wheel steering angle target value δR is compensated for by intervening the rear wheel steering angle speed target τ value δR. be able to.

This point will be specifically explained.

First, assuming a case where differential compensation is not performed, the transmission amount ril of the rear wheel actual steering angle δR with respect to the rear wheel steering angle target value δR at this time (when considering the servo system of the hydraulic cylinder 40) is (where a is a constant and S is a Laplace operator)°, which is a first-order lag form as described above. The servo system at this time is shown in a block diagram as shown in FIG.

On the other hand, if the servo system of this embodiment is represented by an equivalent block diagram, it becomes K as shown in FIG.

The transfer function of the rear wheel actual steering angle δR to the rear wheel steering angle target value δR of this servo system is as follows, and when compared with the above equation (81), it can be seen that the coordination has been improved. In other words, the characteristics are the same as those obtained when the differential compensation of the servo system expressed by equation (al) is performed.

In addition, if it is possible to take KDa > 1, a U
(S) δR(8), and extremely high responsiveness can be obtained.

Next, FIG. 5 shows the configuration of another embodiment of the present invention. In this figure, the same components as those in the embodiment shown in FIG.

In this embodiment, the rear wheel actual steering angular velocity δR fed back to the control circuit 80 is transmitted to the rear wheel actual steering angular velocity δR by the displacement speed sensor 2 as in the embodiment described above.
4, the rear wheel actual steering angle δR detected by the stroke sensor 28 is differentiated using a differentiation circuit 60, so that the actual steering angle δR of the rear wheel is indirectly detected.

Since the output signal of the stroke sensor 28 is an analog signal, a differential output can be obtained using the differential circuit 60.

In this way, by using the differentiating circuit 60, the displacement speed sensor 24 becomes unnecessary, and the structure can be simplified.
Cost reduction can also be achieved.

The differentiating circuit 60 includes, in addition to a true differentiating circuit 61 with a transfer characteristic G=3 as shown in No. 6ml (where τ is a time constant), a -order bypass filter 62, and a bypass filter 62 of the same figure (C).
It is also possible to use a bandpass filter 63 having a transfer characteristic as shown in FIG.

- The frequency characteristics of the differential circuit 61, bypass filter 62, and bandpass filter 6B are shown in FIG. In the same figure, (sword) is the characteristic of the differentiating circuit 61, fBl is the characteristic of the bypass filter 62, and (C) is the characteristic of the bandpass filter 68.

Normally, the frequency range of the actual steering angular velocity of the wheels is A in Fig. 6.
, therefore, if the cutoff frequencies of the bypass filter 62 and the buffed pass filter 8 are set higher than the frequency range A, a differential circuit that is resistant to high frequency noise can be provided.

In addition, in the above embodiment, an example was shown in which the rear wheel steering angle is controlled in order to realize the target driving performance in the own vehicle, but the present invention also provides an example in which the front wheel steering angle is controlled. By controlling the steering angles of both the front wheels and the rear wheels, it is also possible to achieve the driving performance of the vehicle based on the width of the eyes.

(Effects of the Invention) As explained in detail above, the present invention can realize the preset target driving performance as the driving performance of the own vehicle by controlling the steering angle of the wheels. .

In addition, as a means for differentially compensating for the delay in the operation of the actuator that steers the i-wheel, a means for feedback controlling the steering angular velocity of the wheel in the servo system of the actuator is provided, so that differential compensation can be performed without using a differential circuit. It turns out.

As a result, even when differential compensation is difficult to perform using a differential circuit, as in the case where the above-mentioned heavy wheel steering angle control is performed using a digital calculation circuit, appropriate differential compensation can be performed.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the non-inventive system, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 8 is a block diagram of a servo system that does not perform differential compensation, and Fig. 4 is shown in Fig. 2. A block diagram of the servo system in this embodiment, FIG. 5 is a block diagram of another embodiment of the present invention, and FIG. 6 (A1-
(C1 is a circuit diagram showing a specific example of the differential circuit in FIG. 5, and FIG. 7 is a frequency characteristic diagram of each circuit shown in FIG. 6. 100... Steering angle detection means 101... Steering angular speed detection means 102... Vehicle speed detection means 10B... Steering angle target value determination means 104... Steering angular speed target value determination means 105... Actual steering angle detection means 106... Actual steering angular speed detection means 107 ... Rudder angle deviation calculation means 108 ... Rudder angular speed deviation calculation means 109 ... Vehicle width steering means 20 ... Vehicle speed sensor 21 ... Handle steering angle sensor 22 ... Handle steering angular speed sensor 23. ... Stroke sensor 24 ... Displacement speed sensor 30 ... Control circuit 31
... Rear wheel steering angle target value determination section 32 ... Rear wheel steering angle speed target value determination section 40 ... Hydraulic cylinder 45 ... Piston rod 48 , 49 ... Rear wheel 50 ... Control pulp 60 ...Differential circuit θ8...Steering angle θS...Steering angular speed V
...Vehicle speed 1...Current target value iR"'
Rear wheel steering angle target value 6B "' Rear wheel steering angle speed target value δ□... Rear wheel actual steering angle δ.... Rear wheel actual steering angle speed Patent applicant Nissan Motor Co., Ltd. Figure 1 Figure 3 Figure 6 Figure 7

Claims (1)

[Scope of Claims] 1. Steering angle detection means for detecting the steering angle of the steering handle; Steering angular velocity detection means for detecting the steering angular velocity of the steering handle; Vehicle speed detection means for detecting vehicle speed; Steering angle target value determining means for determining a target value of a steering angle of at least one of a front wheel or a rear wheel to be controlled, which corresponds to a steering angle of the steering wheel and a vehicle speed, in accordance with a target driving performance; Steering angular speed target value determining means for determining a target value of the steering angular speed of the controlled object wheel corresponding to the steering angular speed of the steering wheel and the vehicle speed according to motion performance; and an actual steering angle for detecting the actual steering angle of the controlled object wheel. detection means; actual steering angular speed detection means for detecting the actual steering angular speed of the controlled object wheel; steering angle deviation calculation means for calculating the deviation between the steering angle target value and the detected value of the actual steering angle; and the steering angular speed target value. and a steering angular speed deviation calculation means for calculating a deviation between the detected value of the actual steering angular speed, and a steering angle speed deviation calculation means for making both the deviation calculated by the steering angle deviation calculation means and the deviation calculated by the steering angular speed deviation calculation means zero or minimum. A steering angle control device for a vehicle, comprising: a wheel steering means for steering the control target wheel. 2. An input/output transfer characteristic between the steering angle input and the steering angle target value output of the steering angle target value determining means, and an input/output transfer characteristic between the steering angular velocity input and the steering angular velocity target value output of the steering angular velocity target value determining means. The vehicle steering angle control device according to claim 1, wherein the steering angle control device is the same.