JPH0112714B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rear wheel steering angle control device for a vehicle, and particularly to a device for controlling an operating mechanism that produces a steering angle on the rear wheels to produce a steering angle on the front wheels. The present invention relates to a rear wheel steering angle control device for a vehicle (hereinafter referred to as a four-wheel steering vehicle) that automatically controls the steering angle of the rear wheels in accordance with steering of a steering wheel.

[Conventional technology]

A conventional rear wheel steering angle control device for a four-wheel steered vehicle (Japanese Patent Laid-Open No. 57-44568), which is the basis of the present invention, will be explained with reference to FIG.

The shaft 2 rotates together with the rotational steering of the handle 1, and this rotation is transmitted to the gearbox 3 and converted into linear motion of the linkage 4. linkage 4
The linear motion rotates the knuckle arm 5 around the fulcrum 5a, steers the front wheels 6, and gives the front wheels 6 a steering angle δ _f
(t) (where t is time).
A sensor 15 attached to the shaft 2 detects the rotational steering angle δ _h (t) _of the steering wheel 1, and a sensor 7 detects the lateral acceleration V Detect. computer 8
actuates the actuator 9 based on detection signals from the sensors 7 and 15, and applies linear motion to the linkage 14 via the gearbox 10. The linear motion of the linkage 14 rotates the knuckle arm 13 around the fulcrum 13a, steers the rear wheel 12, and causes the rear wheel 12 to produce a steering angle δ _r (t). The steering angle δ _r (t) of the rear wheels is set in the computer 8 as δ _r (t) = K・V 〓 ……(1), which is proportional to the lateral acceleration V 〓, or the steering angle δ r (t) of the front wheels is Adding h・δ _f (t), which is obtained by multiplying the steering angle δ _f (t) by the proportionality constant h, to the right-hand side of the above equation (1), δ _r (t)=h・δ _f (t)+K・V〓… ...(2) is set and controlled.

However, such conventional rear wheel steering angle control devices are not configured to take into account the steering speed of the steering wheel, and the rotational steering angle of the steering wheel is small due to the signal proportional to the rotational steering angle of the steering wheel. Even if the steering angle is large, the rear wheels are steered in the same direction as the front wheels, which has the advantage of improving the running stability of the vehicle when driving straight and making it easier to correct the steering wheel. The responsiveness of the movement is not good, and the structure is not designed to enable turning movement with a small turning radius.

In addition to the device shown in Fig. 2, conventionally, in a four-wheel steering vehicle in which a steering device for steering the front wheels and a steering device for steering the rear wheels are mechanically connected, when the rotational steering angle of the steering wheel is small, In this case, the rear wheels are steered in the same direction as the front wheel steering angle, and when the steering angle of the steering wheel is large, the rear wheels are steered in the opposite direction to the front wheel steering angle.
A device for controlling the steering angle of the rear wheels has also been proposed.

However, in this type of device, the rear wheels are steered in the same direction or in the opposite direction as the front wheels depending on the magnitude of the rotational steering angle of the steering wheel, and the speed at which the driver turns the steering wheel is controlled. For example, when the driver responds to an emergency maneuver that requires rapid turning movements such as obstacle avoidance or lane change, and when the driver performs normal steering such as driving straight ahead or making a gentle turn. Even if you change the steering speed of the steering wheel in anticipation of different motion characteristics, if the rotational steering angle of the steering wheel is constant, the steering angle of the rear wheels will remain constant in the specified direction. The structure is controlled by

Therefore, the conventional four-wheel steering vehicle described above has a problem in that it cannot fully satisfy the driving characteristics expected by the driver depending on the steering speed of the steering wheel.

Therefore, the present inventors have developed a rear wheel steering angle that always turns the rear wheels in the same direction as the front wheels when the vehicle speed and other conditions are the same and the steering speed of the steering wheel is changed to make the rotational steering angle equal. As a result of running tests comparing the dynamic characteristics of a four-wheel steered vehicle equipped with a control device and a four-wheel steered vehicle equipped with a rear wheel steering angle control device that always steers the rear wheels in the opposite direction to the front wheels, we found that the steering wheel The present invention was developed based on the need to develop a rear wheel steering angle control device that controls the direction of the rear wheel steering angle in accordance with the steering speed, that is, the angular frequency.

[Purpose of the invention]

In consideration of the above points and in order to solve the conventional problems, the present invention focuses on the steering speed of the steering wheel and improves the responsiveness of the turning movement in situations where rapid turning movement is required. An object of the present invention is to provide a rear wheel steering angle control device for a vehicle that improves straight running stability under conditions where slow turning motion is required.

[Summary of the invention]

In order to achieve the above object, the present invention provides a vehicle that automatically controls the steering angle of the rear wheels in response to steering of a steering wheel that controls an operating mechanism that generates a steering angle of the rear wheels to generate a steering angle of the front wheels. In a rear wheel steering angle control device, a detection means for detecting a steering amount of a steering wheel and outputting a steering amount signal, a determining means for determining a steering speed of the steering wheel based on the steering amount signal, and a determination by the determining means. Based on the results, when the steering speed of the steering wheel is fast, the rear wheels produce a steering angle in the opposite direction to the front wheels, and when the steering speed is slow, the rear wheels produce a steering angle in the same direction as the front wheels. and a control means for controlling the operating mechanism.

According to the present invention, the displacement D of the steering wheel with respect to the rotational steering angle δ _h (t) of the steering wheel or the position of the steering wheel corresponding to the straight-ahead direction of the vehicle is determined by the detection means.
That is, an amount corresponding to the steering angle of the front wheels is detected as the steering amount. When the rotational steering angle δ _h (t) of the steering wheel is detected, the angular frequency ω of the steering wheel is determined by differentiating the rotational steering angle with respect to time t, and when the displacement D of the steering wheel is detected,
Displacement D is expressed as X=f using the angular frequency ω of the handle.
It is expressed as (ωt). Therefore, the determining means can determine the steering speed of the steering wheel based on the steering amount signal output from the detecting means.
When the steering speed of the steering wheel, that is, the angular frequency is high, the control means controls the operating mechanism so that the rear wheels have a steering angle in the opposite direction to the front wheels, and the steering angles are applied to the front and rear wheels almost simultaneously. This generates forces on the tires, and these forces become yawing moments that rotate in the same direction, equivalently increasing the ratio of the steering angle of the steered wheels to the rotational steering angle of the steering wheel, the so-called steering gain (in this case, , the steering angle of the steering wheel is equivalently the sum of the steering angle of the front wheels and the steering angle of the rear wheels), and the responsiveness of the turning motion of the vehicle is improved.
On the other hand, when the steering speed of the steering wheel, that is, the angular frequency, is small, the control means controls the operating mechanism so that the rear wheels have a steering angle in the same direction as the front wheels, so that the steering angle of the steered wheels is equivalent to that of the front wheels. The steering gain decreases due to the difference between the steering angle and the steering angle of the rear wheels, improving the straight-line stability of the vehicle.

〔Effect of the invention〕

Therefore, according to the present invention, when the steering wheel is steered quickly, that is, when the angular frequency of the steering wheel is high, the steering gain is increased to improve the responsiveness of rapid turning movements of the vehicle, and when the angular frequency of the steering wheel is small, the steering gain is increased. The effect of reducing the steering gain is that it is possible to prevent the vehicle from wobbling, wandering, etc., and to improve running stability when the vehicle is traveling straight.

[Description of aspects of the invention]

Next, aspects of the present invention will be explained. The present invention can take the following aspects. In a first aspect, the control means causes the rear wheels to produce a steering angle in the opposite direction to the front wheels when the speed of steering the steering wheel is high based on the determination result of the determination means and the steering amount signal, and controls the steering angle of the steering wheel in the opposite direction to that of the front wheels. When the speed is slow, the operating mechanism is controlled so that the rear wheels have a steering angle in the same direction as the front wheels, and the rear wheels have a steering angle of a magnitude corresponding to the steering amount signal.

According to this first aspect, the direction in which the steering angle of the rear wheels is generated is controlled according to the steering speed of the steering wheel, and the magnitude of the steering angle of the rear wheels is controlled according to the steering amount signal.

Therefore, the ratio between the front wheel steering angle and the rear wheel steering angle can be optimally determined by the steering amount signal, and if necessary, the front wheel steering angle and the rear wheel steering angle can be adjusted according to the driver's preference. This has the advantage that the steering angle ratio can be set appropriately.

In the second aspect, the determining means has the following transfer function G
(S), and the control means controls the actuating mechanism based on the result.

G(S)=Kd−Ke/1+TS・TS...(3) However, Kd, Ke are constants of magnitude satisfying the condition 0<Kd<Ke, and S is the complex frequency expressed by a+jω (however, a is any real number independent of time t, j=√-1), T is the first-order lag time constant. As is well known, the transfer function G(S) is the Laplace transform form of the output, that is, the steering angle δ _r (t) of the rear wheels.
The image function δ _r (S) obtained by Laplace transform is the input Laplace transform form, for example, the rotational steering angle of the steering wheel δ _h (t)
is divided by the Laplace-transformed image function δ _h (S).

That is, in the second aspect, the actuation mechanism is controlled using a transfer characteristic expressed by an element obtained by subtracting an element in which a first-order delay element and a differential element are connected in series from a proportional element.

As a conventional transfer characteristic of this type of device, there is, for example, the following transfer function G(S) expressed by the ratio of a proportional element and a first-order lag element.

G(S)=δ _r (S)/δ _h (S)=Ke/1+TS……(4
) However, Ke>0.

This transfer function G(S) becomes G in the limit of S→0.
(S) = Ke, and in the limit of S→∞, G(S) = 0, so if the steering wheel is turned slowly, the rear wheels will have a steering angle in the same direction as the front wheels, and if the steering wheel is turned quickly, the steering angle of the rear wheels will be in the same direction as the front wheels. The rear wheels have a characteristic that the steering angle is zero or a small value close to zero in the same direction as the front wheels. In other words, compared to conventional vehicles that do not control the steering angle of the rear wheels, when the steering wheel is turned slowly, the rear wheels are controlled in the same direction as the front wheels to improve straight-line stability. It is simply maintained at the same level as conventional vehicles.

Therefore, the inventors have arrived at a rear wheel steering angle control device that is controlled by a transfer function that satisfies the following conditions.

(a) For fast steering, that is, for steering with a high steering angular frequency, the rear wheel steering angle should be set to be opposite to the front wheel steering angle by minimizing the delay in front wheel steering. When the steering wheel is turned slowly, the response level of the rear wheels is reduced to weaken the influence on the steering wheel. The transfer function G(S) that satisfies this condition is as follows, and is expressed by a proportional element, a first-order lag element, and a differential element.

G(S)=Kd-Ke/1+TS・TS...(5) (0<Kd<Ke) (b) For steering with a slow steering wheel, that is, steering with a small angular frequency of the steering wheel, the steering angle of the rear wheels should be changed. The steering angle is controlled in the same direction as the front wheel steering angle, and when the steering wheel is turned quickly, the response level of the rear wheels is reduced to weaken the influence on the steering wheel. The transfer function G(S) that satisfies this condition is as follows,
It is expressed by a proportional element and a first-order lag element.

G(S)=Kd/1+TS...(6) (0<Kd) The transfer function G(S) that satisfies the conditions (a) and (b) above is:
From equations (5) and (6), we get the following.

G(S)=Kd-Ke/1+TS・TS+Kd/1+TS=Kd-Ke/1+TS・TS...(7) In order to explain the characteristics of equation (7) above, we will explain the case where the steering wheel is steered extremely slowly and the case where the steering wheel is turned extremely slowly. Consider a case where the vehicle is steered extremely quickly. When the steering wheel is turned extremely slowly, the complex frequency S becomes an extremely small value, and at its limit S→0, the above equation (7) becomes as follows.

lim S→0G(S)=Kd...(8) Since Kd>0, if the input is the rotational steering angle of the steering wheel δ _h (t), the steering angle of the rear wheels δ _r (t) and the rotation of the steering wheel The steering angle δ _h (t) has the same sign,
The steering angle of the rear wheels is controlled in the same direction as the steering angle of the front wheels.

On the other hand, when the steering wheel is turned extremely quickly, the complex frequency S becomes an extremely large value, and at its limit S→∞, the above equation (7) becomes as follows.

lim S→∞G(S)=Kd−Ke ...(9) Since Ke>Kd, Kd−Ke<0, and if the input is the rotational steering angle of the steering wheel δ _h (t), the steering angle of the rear wheels is δ _r (t) and the rotational steering angle δ _h (t) of the steering wheel have opposite signs, and the steering angle of the rear wheels is controlled in the opposite direction to the steering angle of the front wheels.

Also, in the above case, the steering angle δ _r (t) of the rear wheels
is proportional to the rotational steering angle δ _r (t) of the steering wheel with respect to the constants Kd and Kd−Ke, so the magnitude of the steering angle of the rear wheels is controlled in proportion to the magnitude of the rotational steering angle of the steering wheel.

Note that although the rotational steering angle of the steering wheel is used as an input in the above, the same control can be performed using the displacement D of the steering wheel.

As described above, according to the second aspect, the direction and magnitude of the steering angle of the rear wheels are controlled according to the steering speed of the steering wheel, and the values of the constants Kd, Ke, and time constant T are optimally determined. This has the advantage that the magnitude and direction of the steering angle of the rear wheels can be optimally controlled according to the steering speed of the steering wheel.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram of a four-wheel steering vehicle connected to a basic circuit according to an embodiment of the present invention. A handle (steering wheel) 1 is connected to a gearbox 3 via a shaft 2. Linkages 4 are connected to both ends of the gearbox 3, and a front wheel 6 is connected to each linkage 4 via a knuckle arm 5. The rear wheel 12 is connected to both ends of a steering link mechanism that includes a knuckle arm 13 and a linkage 14, similar to the front wheel 6.

A detection means 20 that continuously detects the amount of steering of the steering wheel 1 is connected to the shaft 2, and this detection means 20 is connected to an actuation mechanism 28 via a control means 26 composed of a judgment circuit 22 and a control circuit 24. has been done.

The determination circuit 22 determines the magnitude of the angular frequency ω of the steering wheel, that is, the speed of steering, based on the steering amount signal output from the detection means 20. Control circuit 2
4 is based on the judgment result of the judgment circuit 22 and the steering amount signal, and when the steering speed of the steering wheel is fast, causes the rear wheels to produce a steering angle in the opposite direction to that of the front wheels, and the magnitude corresponds to the steering amount signal. On the other hand, when the steering speed is slow, the rear wheels are caused to have a steering angle in the same direction as the front wheels, and a steering angle of a magnitude corresponding to the steering amount signal is output. Outputs a control signal. The actuation mechanism 28 controls the direction and magnitude of the steering angle of the rear wheels based on this control signal.

Next, specific examples of the present invention will be described.
In the following description, parts corresponding to those in FIG. 1 are designated by the same reference numerals.

FIG. 3 is a circuit diagram showing a first specific embodiment of the present invention. The rear wheel steering angle control device of the first specific embodiment includes a detection means 50 for detecting the rotational steering angle of the steering wheel 1, and a steering angle signal connected to the detection means 50 and outputted from the detection means. a determination circuit 201 that determines the steering speed, that is, the angular frequency of the steering wheel, based on the rate of change of the steering angle signal; and a control circuit 251 that outputs a control signal corresponding to the steering speed of the steering wheel based on the determination signal output by the determination circuit 201. It is connected to the control circuit 251 and is installed in the vehicle body to generate force in response to a control signal, and this force is transmitted to the rear wheels when the steering wheel is slowly steered, that is, when the angular frequency is small. The rear wheels are steered in the same direction as the front wheels, and if the steering wheel is steered quickly, that is, the angular frequency is large, the rear wheels are steered in the opposite direction to the front wheels. It is composed of an actuation mechanism 80 that generates. The determination circuit 201 and control circuit 251 described above constitute a signal processing circuit 200.

The detection means 50 is constituted by a rotary potentiometer RP which is made up of an arc-shaped resistor 502 and a slider 504 and is fixed to the body B of the vehicle. One end of the slider 504 is locked to the tip of the shaft 2. Rotating potentiometer with predetermined voltage
When RP is applied, the shaft 2 rotates according to the rotational steering angle δ _h (t) of the handle 1, and the other end of the slider 504 slides along the resistance 502.
A voltage signal corresponding to the steering angle δ _h (t) of the steering wheel 1 is outputted from the detection means as a steering angle signal. This steering angle signal is the rotational steering angle δ _h (t) of the steering wheel 1
It is a voltage signal proportional to the rotational steering angle of the steering wheel δ _h (t) = 0 (the steering angle of the front wheels 6 with respect to the straight-ahead direction δ _f
(t) = 0 state), when the steering wheel 1 is rotated to the right, the polarity becomes positive, and when the steering wheel 1 is rotated and steered to the left, the polarity is negative.

The judgment circuit 201 includes a first sample and hold circuit 100, a differential amplifier circuit 110, a second sample and hold circuit 120, an absolute value circuit 130, an oscillator 213, a monostable multivibrator (hereinafter referred to as monomulticircuit) 214, and a comparison circuit. It consists of 140. This judgment circuit 201 determines the change value of the steering angle signal from the detection means 50 at fixed time intervals in order to judge the steering speed of the steering wheel 1 based on the steering angle signal output from the detection means 50. This circuit compares the absolute value of the voltage signal corresponding to the change rate signal with a predetermined voltage level.

The steering angle signal output from the detection means 50 is sent to the input terminal of the analog switch 202 of the first sample hold circuit 100 and the differential amplifier circuit 110.
is supplied to the resistor 207. The first sample and hold circuit 100 includes an analog switch 2 whose control terminal is connected to a mono multi-circuit 214.
02, capacitor 203 and operational amplifier 204
A steering angle signal is sampled by an analog switch 202 which is opened and closed by a pulse signal output from a monomulti circuit 214, and the sampled signal is held in a capacitor 203. Therefore, the first sample and hold circuit 10
0, as shown in FIG. 4A, the steering angle signal X, which is a continuous signal, is converted into discrete values by a pulse signal at fixed time intervals output from the monomulti circuit 214, and a stepped voltage signal _Vs is output. do. differential amplifier circuit 110, operational amplifier 209 and resistor 205,
206, 207, and 208, one end of the resistor 205 is supplied with the stepped voltage signal V _s output from the first sample and hold circuit 100, and one end of the resistor 207 is supplied with the steering angle signal from the detection means 50. X is supplied, and these two signals V _s and X are operated. Therefore, the differential amplifier circuit 110
As shown in Figure B, a voltage signal is output from the first sample and hold circuit 100 from the steering angle signal
Outputs a sawtooth voltage signal V _sa obtained by subtracting V _s . This voltage signal V _sa corresponds to a change value of the steering angle signal X at fixed time intervals, that is, a change rate signal.

Like the first sample and hold circuit 100, the second sample and hold circuit 120 is composed of an analog switch 210, a capacitor 211, and an operational amplifier 212.
The sawtooth waveform voltage signal V _sa from the differential amplifier 110 is supplied to the input terminal of the analog switch 210 , and the oscillator 21 is supplied to the control terminal of the analog switch 210 .
A pulse signal from 3 is supplied. This second
The sample hold circuit 120 of the oscillator 213
When the pulse signal that is output from the differential amplifier and rises only for a short time is on, the voltage signal V sa output from the differential amplifier is sampled and the voltage signal V _sa is output from the capacitor 2.
Hold at 11. The output pulse signal of the oscillator 213 is supplied to the analog switch 202 via a monomulti circuit 214 that operates with a negative edge trigger (operates at the rising edge of the signal).
Since it is supplied to the analog switch 210,
Immediately after the analog switch 210 changes from the on state to the off state, the analog switch 202 turns on. Therefore, as shown in FIG. 4B, the second sample and hold circuit 120 outputs the voltage signal V _d at regular intervals in accordance with the rate of change signal output from the differential amplifier circuit. That is, the second sample and hold circuit 120 outputs a voltage signal V _d at fixed time intervals based on the steering angle signal X from the detection means 50 in accordance with the steering speed of the steering wheel at fixed time intervals.

In addition, in FIGS. 4A and 4B, to simplify the explanation, the rising intervals of the pulse signals that are the outputs of the monomulti circuit 214 and the oscillator are shown wide, but the oscillation frequency of the pulse signals varies depending on the steering angle. It is desirable that the frequency of the signal is approximately 10 ³ times or more the frequency of the steering angle of the steering wheel.

The absolute value circuit 130 includes resistors 215, 216, 2
20, 221, 222, diode 217, 21
8 and operational amplifiers 219 and 223, and outputs the absolute value of the voltage signal V _d corresponding to the steering speed outputted from the second sample hold circuit 120 at fixed time intervals. This absolute value circuit 13
0, as shown in Figure 5, outputs a positive slope voltage for the right steering speed, and outputs a negative slope voltage for the left steering speed, resulting in an overall positive slope. Outputs only polar output voltage V.

The comparator 140 includes operational amplifiers 224, 225,
226, 227 and voltage sources 228, 229 that generate positive voltages, the output voltage V from the absolute value circuit 130 is set to predetermined voltage levels e ₁ , e ₂ (e ₁ < Compare with _e2 ). The operational amplifier 224 has a non-inverting input terminal (positive terminal) supplied with the output voltage V from the absolute value circuit 130 and an inverting input terminal (negative terminal) supplied with the voltage source 228.
As shown in _FIG . A high level voltage signal _V3 is output only when the positive voltage _e2 is greater than the positive voltage e2.
The operational amplifiers 225 and 226 form a window comparator, and the negative terminal of the operational amplifier 225 and the positive terminal of the operational amplifier 226 are connected to form the absolute value circuit 1.
30 is supplied with an output voltage V from operational amplifier 2
The positive terminal of 25 receives a positive voltage e ₂ from a voltage source 228.
is supplied, and a positive voltage e ₁ (e ₁ <e ₂ ) from a voltage source 229 is supplied to the negative terminal of the operational amplifier 226 . And operational amplifiers 225, 226
The output terminals of are connected to each other, and as shown in FIG. 6B, the output voltage V from the absolute value circuit 130 corresponding to the steering speed for each fixed time is e ₁ ≦V≦e ₂
A high level voltage signal V ₂ is output only when .
The operational amplifier 227 has an absolute value circuit 130 at its negative terminal.
The comparator is supplied with the above voltage V from the voltage source 229 and the positive voltage _e1 from the voltage source 229 is supplied to the positive terminal, and as shown in FIG. 6A, it corresponds to the steering speed at fixed time intervals. A high level voltage signal V ₁ is output only when the output voltage V from the absolute value circuit 130 is smaller than the positive voltage e ₁ from the voltage source 229.

The operation of the judgment circuit 201 explained above will be explained. Based on the steering angle signal outputted from the detection means 50, the judgment circuit 201 converts the steering angle signal into a change rate signal by determining the change value of the steering angle signal at fixed time intervals, and calculates the voltage signal corresponding to the change rate signal. Compare the absolute value to a predetermined voltage level. Then, based on this comparison, the steering speed of the steering wheel 1 is determined, and when the steering speed of the steering wheel 1 is slow, the operational amplifier 22
7 outputs a high level voltage signal, and when the steering speed of the steering wheel is fast, a high level voltage signal is output from the operational amplifier 224. Furthermore, when the steering speed of the steering wheel is intermediate between the above two, the operational amplifiers 225 and 22 connected to each other
6 outputs a high level voltage signal.

The control circuit 251 includes the inverting amplifier circuits 150 and 16
0 and analog switches 252, 253, 254, the steering angle signal from the detection means 50 and the voltage signals V ₁ , V ₂ , from the judgment circuit 201,
Based on V ₃ , a control signal corresponding to the steering speed of the steering wheel 1 is output.

A voltage signal V ₃ from the operational amplifier 224 of the judgment circuit 201 is supplied to the control terminal of the analog switch 252 .
The output signal of the inverting amplifier circuit 150 is supplied to the input terminal of the inverting amplifier circuit 150 . Further, the control terminal of the analog switch 253 is supplied with the voltage signal V ₂ from the operational amplifiers 225 and 226 of the judgment circuit 201, and the input terminal of the analog switch 253 is grounded. The control terminal of the analog switch 254 is supplied with the voltage signal V ₁ from the operational amplifier 227 of the determination circuit 201 , and the input terminal of the analog switch 254 is supplied with the output signal of the inverting amplifier circuit 160 . The above-mentioned inverting amplifier circuit 150 includes an operational amplifier 257, an input resistor 25
5 and a feedback resistor 256, the steering angle signal from the detection means 50 supplied to one end of the input resistor 255 is inverted amplified ( _{-K A} times)
and output it. Further, the inverting amplifier circuit 160 is composed of an operational amplifier 260, an input resistor 258, and a feedback resistor 259 similarly to the inverting amplifier circuit 150,
Detection means 50 supplied to one end of input resistor 258
Input the steering angle signal from the input resistor 258 and the feedback resistor 2
Inverting amplification (-
1) and output.

The operation of the control circuit 251 configured as above will be described. When the steering speed of the steering wheel 1 is fast, only the operational amplifier 224 of the judgment circuit 201 outputs a high level voltage signal _V3 , and the analog switch 252 is turned on. On the other hand, the steering angle signal from the detection means 50 is transmitted to the inverting amplifier circuit 150.
The signal is multiplied by -K _A and input to the analog switch 252. Therefore, when the steering wheel is turned quickly, the control circuit 251 outputs the steering angle signal to −K _A
The multiplied signal is output as a control signal. When the steering speed of the steering wheel 1 is slow, only the operational amplifier 227 of the judgment circuit 201 outputs a high level voltage signal.
V ₁ is output, and the analog switch 254 is turned on. On the other hand, the steering angle signal from the detection means 50 is processed by two inverting amplifier circuits 150 and 160.
The signal is multiplied by K _A and input to the analog switch 254. Therefore, when the steering speed of the steering wheel is slow, the control circuit 251 outputs a signal obtained by multiplying the steering angle signal by K _A as a control signal. If the steering speed of the steering wheel 1 is between the above two, the operational amplifiers 225 and 2 of the judgment circuit 201
Only 26 outputs a high level voltage signal _V2 ,
The analog switch 253 is turned on. On the other hand, since the input terminal of the analog switch 253 is grounded, if the steering speed of the steering wheel is between the above two, the control circuit 251 outputs a signal with zero voltage as a control signal.

The operating mechanism 80 is connected to the flow control valve SV through a hydraulic pressure generator P, an accumulator AL, a flow control valve SV, an oil reservoir T that communicates with the suction side of the hydraulic pressure generator P to return unnecessary oil, and piping. It consists of an actuator AC, a knuckle arm 13 having a fulcrum 13a, and steering linkages SL, which connect the left and right knuckle arms 13, 13 via pin joints SL _a , SL _a .

The hydraulic pressure generator P is composed of a vane pump driven by the engine via a pulley, and stores a predetermined pressure in the accumulator AL in advance. This vane pump is driven according to the rotation of the engine.

The accumulator AL consists of a metal container 30 having a predetermined capacity.The metal container 30 is divided into two by a rubber diaphragm 32, one chamber is filled with gas such as nitrogen at a predetermined pressure, and the other chamber is filled with a gas such as nitrogen at a predetermined pressure. is configured to communicate with a discharge port of a vane pump that constitutes the hydraulic pressure generator P via piping. This accumulator AL compensates for the inoperability of the rear wheel steering angle control device when the capacity of the vane pump is insufficient to meet the requirements of the rear wheel steering angle control device of the vehicle. Further, by providing the accumulator AL, it is possible to downsize the vane pump and reduce its capacity. The accumulator AL is connected to the flow control valve SV via piping, and the hydraulic pressure accumulated in the accumulator AL is transferred to the actuator AC according to the valve opening degree of the flow control valve SV.
supply to

The flow rate control valve SV is composed of a spool valve consisting of a cylinder in which an inflow port and a discharge port are arranged, and a spool that moves the cylinder in the axial direction. By changing the positional relationship with the port, the opening area of the throttle is changed to control the discharge flow rate.

The actuator AC consists of a cylinder 34 connected to the discharge port of the flow control valve SV via piping and a piston 36 that moves in the axial direction inside the cylinder 34. 36 is configured by locking both ends to left and right steering ring gauges SL, SL.

The effects of the vehicle rear wheel steering angle control device of this embodiment configured as described above will be explained below.
In addition, in the following, handle 1 is used to simplify the explanation.
Consider the case where the vehicle is steered to the right by an angle δ _h (t).

By rotating the handle 1 to the right, the shaft 2 also rotates as the handle rotates. Along with this, the detection means 5 locked on the tip of the shaft 2
The slider of the rotary potentiometer 0 is slid, and the rotational steering angle δ _h of the handle is detected from the detection means 50.
A steering angle signal X corresponding to (t) is output. At this time, the front wheels 6 are steered to the right as in the conventional case, producing a steering angle δ _f (t). This steering angle signal
1 is input.

The determination circuit 201 determines the change value of the steering angle signal X at fixed time intervals, converts the steering angle signal X into a change rate signal, and compares the absolute value of the voltage signal corresponding to the change rate signal with a predetermined voltage level. The steering speed of the steering wheel at fixed time intervals is determined by The control circuit 251 outputs a steering angle signal X when the steering speed of the steering wheel is slow, depending on the steering speed of the steering wheel 1 at fixed time intervals determined by the determination circuit 201.
Outputs the control signal Y = K _A・X multiplied by K _A , and when the steering speed of the steering wheel is fast, the steering angle signal
Outputs a control signal Y=-K _A・X multiplied by K _A , and outputs a control signal Y=0 with zero voltage when the steering speed of the steering wheel is between the above two speeds. .

The flow control valve SV of the actuation mechanism 80 receives a control signal Y
The hydraulic pressure of the accumulator AL is introduced into the actuator AC. Therefore, the pressure inside the cylinder of actuator AC changes and the piston is moved. This piston moves the steering linkage SL, rotates the knuckle arm 13 about the fulcrum 13a, and steers the rear wheel 12 to produce a steering angle δ _r (t). That is, the rear wheel 12
When the polarity of the control signal Y is positive, the actuation mechanism 80 generates a steering angle δ _r (t) in the same direction as the steering direction of the steering wheel 1, that is, to the right, which corresponds to the voltage obtained by multiplying the steering angle signal by K _A. only to be steered. On the other hand, the control signal Y
When the polarity of is negative, the rear wheels 12 are steered in the opposite direction to the steering direction of the steering wheel 1, that is, to the left, by a steering angle δ _r (t) corresponding to the voltage obtained by multiplying the steering angle signal by K _A. Ru. Note that when the control signal Y is zero, the rear wheels 12 are not steered and the steering angle δ _r (t) of the rear wheels becomes zero.

As described above, according to this embodiment, when the steering speed of the steering wheel is slow, the rear wheels are steered in the same direction as the steering angle of the front wheels, and when the steering speed is fast, the rear wheels are steered in the same direction as the steering angle of the front wheels. If the rear wheels are steered in the opposite direction to generate a steering angle proportional to that of the front wheels, and the steering wheel is steered at a speed intermediate between the above two, the rear wheels will be steered in the opposite direction. The steering angle of the rear wheels can be made zero without steering the wheels. In this way, in this embodiment, the magnitude and direction of the steering angle of the rear wheels can be controlled in accordance with the steering speed of the steering wheel by applying a force to the rear wheels that corresponds to the steering speed of the steering wheel. This has the advantage that both the stability of the vehicle when traveling straight and the responsiveness of turning motion can be improved. Furthermore, in this embodiment, it is possible to detect the steering angle of the steering wheel, determine the steering speed of the steering wheel from one steering angle signal, and determine the direction of steering of the rear wheels and the magnitude of the steering angle. Therefore, it has the advantage that it is not necessary to have both a means for detecting the steering speed of the steering wheel and a means for detecting the rotational steering angle of the steering wheel, so that it is suitable for being mounted on a vehicle.

Although the above example uses a rotary potentiometer, it is also possible to use a so-called rotary encoder that generates pulses in response to the rotational steering of the steering wheel, and it is also possible to use a speed sensor to control the steering of the steering wheel. It is also possible to detect speed. Alternatively, the steering speed of the steering wheel may be determined by differentiating the steering angle signal using a differentiator as a judgment circuit, or the steering speed of the steering wheel may be further divided by increasing the number of comparators of the comparator 140. Alternatively, the rear wheels may be controlled by determining the steering speed. Furthermore, as an operating mechanism, if necessary, a means for detecting the steering angle of the rear wheels is provided, and the control signal output from the control circuit is used as a target value signal, and the output from the means for detecting the steering angle of the rear wheels is set as a target value signal. It is also possible to use so-called feedback control in which a deviation signal, which is the difference between the target value signal and the actual measurement value signal, is obtained as the actual measurement value signal, and the flow control valve is controlled to steer the rear wheels so that the deviation signal becomes zero. good. In this case, if large electrical power is required, it is also possible to use means such as an amplifier for amplifying the deviation signal.

Next, a second specific example of the present invention will be described. FIG. 7 is a circuit diagram of a second specific embodiment. The second specific embodiment of the rear wheel steering angle control device is as follows:
A detection means 60 detects the displacement of the steering wheel 1, and the steering speed of the steering wheel is determined by the angular frequency of the steering wheel based on the displacement signal connected to the detection means 60 and outputted by the detection means, and the steering angle of the steering wheel is determined. A signal processing circuit 300 that outputs a control signal whose phase lags by up to 180 degrees with respect to the input displacement signal as the frequency increases and is amplified at a constant amplification factor regardless of the angular frequency of steering the steering wheel. , which is connected to the signal processing circuit 300 and installed in the vehicle body, generates force in response to a control signal, and transmits this force to the rear wheels to control the steering wheel when the steering wheel is turned slowly. In the region where the angular frequency is small, the rear wheels are steered in the same direction as the front wheel steering angle, and in the region where the angular frequency of the steering wheel is large, which corresponds to when the steering wheel is turned quickly, the rear wheels are steered in the opposite direction to the front wheel steering angle. and an actuation mechanism 90 that steers the rear wheels to generate a steering angle at the rear wheels.

The rear wheel steering angle control device of the second specific embodiment adds a change to the signal processing circuit 200 of the first specific embodiment described above, so that the steering wheel steering angle can be controlled without determining the rate of change signal from the output of the detection means. The main differences are that the steering speed of the steering wheel is determined based on the angular frequency of , and that a control signal corresponding to the steering speed of the steering wheel is output by shifting the displacement signal It is. The differences will be mainly explained below, and the same parts will be given the same reference numerals to simplify the explanation.

The detection means 60 consists of a linear resistor 602 and a slider 604, and is constituted by a linear potentiometer SP fixed to the body B of the vehicle. One end of the slider 604 is locked to a gear built into the gearbox 3. Steering angle δ _h of handle 1
When the shaft 2 rotates in accordance with (t), this rotational movement is transferred to the slider 604 by a movement converting mechanism such as a rack and pinion built into the gearbox 3.
is converted into linear motion of the locked gear. The detection means 60 detects this linear movement as a displacement corresponding to the steering angle δ _h (t) of the handle 1 using a linear potentiometer SP, and outputs a voltage signal corresponding to the displacement as a displacement signal D. Here, to simplify the explanation, assuming that the steering wheel 1 is continuously steered in a sinusoidal manner at an angular frequency ω, the rotational steering angle δ _h (t) of the steering wheel is expressed as ωt, so the straight direction is used as the reference. The displacement of the steering wheel at the rotational steering angle ωt is δ _h0・sinωt (where δ _h0 is the amplitude of the steering wheel)
Accordingly, the displacement signal D output from the linear potentiometer SP is also a sinusoidal continuous voltage signal D=D ₀ with an amplitude D ₀ corresponding to the amplitude of the handle and an angular frequency ω. sinωt.

The signal processing circuit includes a phase shift circuit 301 connected to the slider of the detection means 60 and a coefficient multiplier 351.

The phase shift circuit 301 includes an operational amplifier 306 and a resistor 3.
02, 303, 304 and a capacitor 305, and the resistance values of the input resistor 302 and the feedback resistor 303 are set to be equal. Resistor 3 above
04 and the capacitor 305 correspond to the judgment circuit of the first specific embodiment, and the resistors 302 and 303, the operational amplifier 306 and the coefficient multiplier 351 correspond to the control circuit.

In the phase shift circuit 301, when the angular frequency ω of the input displacement signal D is small and close to zero, the reactance of the capacitor 305 becomes close to infinity,
A signal is input to the positive terminal of the operational amplifier 306 via a resistor 304 to which the displacement signal D is supplied to one end. At the same time, the displacement signal D is also applied to the input resistor 302, and the input resistor 302 and feedback resistor 303
Since the resistance ratio of is 1, the signal input to the negative terminal of operational amplifier 306 outputs a signal with a gain of -1. On the other hand, a signal with a gain of 2 is output from the signal input to the positive terminal of the operational amplifier 306,
The phase shift circuit 301 as a whole provides an output with a gain of 2-1=1. Therefore, when the angular frequency of the displacement signal D is small and close to zero, an output signal D equal to the input displacement signal D is obtained.

On the other hand, when the angular frequency ω of the input displacement signal D is large and close to infinity, the capacitor 305 is almost short-circuited, and the positive terminal of the operational amplifier 306 is equivalent to being grounded. At this time,
A signal is input only to the negative terminal of the operational amplifier 306, and the phase shift circuit 301 functions only as an inverting amplifier itself. In this case, since the resistance ratio between the input resistor 302 and the feedback resistor 303 is 1, the gain is -
It becomes 1. Therefore, if the angular frequency ω of the displacement signal D is large and close to infinity, the input displacement signal D
An output signal -D is obtained by inverting the output signal -D. This output signal -D has an absolute value (amplitude D ₀ ) equal to the input,
This is a signal whose phase is delayed by 180° with respect to the input signal.

According to the operating principle as described above, the phase shift circuit 301
As the angular frequency of the displacement signal D increases,
Outputs an output signal whose phase is delayed from 0° to a maximum of 180° with respect to the displacement signal D.

The coefficient multiplier 351 amplifies the output signal from the phase shift circuit 301 by a constant value K _A and outputs a control signal Y.

The actuation mechanism 90 is connected to the flow control valve SV through a hydraulic pressure generator P, an accumulator AL, a flow control valve SV, an oil reservoir T that communicates with the suction side of the hydraulic pressure generator P to return unnecessary oil, and piping. It is comprised of an actuator AC, a knuckle arm 13 having a fulcrum 13a, and a steering linkage SL that connects the left and right knuckle arms 13, 13 via pin joints SL _a , SL _a .

The hydraulic pressure generator P is composed of a vane pump driven by the engine via a pulley, and stores a predetermined pressure in the accumulator AL in advance. This vane pump is driven according to the rotation of the engine.

The accumulator AL consists of a metal container 30 having a predetermined capacity.The metal container 30 is divided into two by a rubber diaphragm 32, one chamber is filled with gas such as nitrogen at a predetermined pressure, and the other chamber is filled with a gas such as nitrogen at a predetermined pressure. is configured to communicate with a discharge port of a vane pump that constitutes the hydraulic pressure generator P via piping. This accumulator AL is connected to the flow rate control valve SV via piping, and supplies the hydraulic pressure accumulated in the accumulator AL to the actuator AC according to the valve opening degree of the flow rate control valve SV.

The flow rate control valve SV controls the discharge flow rate by changing the opening area of the aperture according to the control signal Y from the signal processing circuit 300.

In the actuator AC, unlike the first specific embodiment, the cylinder part 34 is locked to the vehicle body B, the rod 38 protruding from the cylinder part 34 is fixed to the piston part 36, and the tip of the rod 38 is connected to the knuckle arm 13. It is locked to. The cylinder portion 34 of the actuator AC is connected to the discharge port of the flow control valve SV. Further, the actuator AC is arranged approximately parallel to the steering linkage SL that connects the left and right knuckle arms 13, 13 via pin joints SL _a , SL _a , and the tip of the rod fixed to the piston part is connected to the knuckle arm 13. Fulcrum 13a and pin joint
It is locked to the knuckle arm 13 at an intermediate position with SL _a .

The effects of the vehicle rear wheel steering angle control device of the second specific embodiment configured as described above will be described below.

Consider the case where the steering wheel 1 is continuously steered in a sinusoidal manner with an amplitude δ _h0 and an angular frequency ω as described above, that is, a case where the steering wheel 1 is steered at a rotational steering angle δ _h (t)=δ _h0 ·sinωt. In response, the detection means 60 detects the amplitude
A sinusoidal continuous displacement signal D=D ₀ ·sinωt having an angular frequency ω at D ₀ is output. Then, the signal processing circuit 300 processes the displacement signal D according to the angular frequency ω that the displacement signal D has, and outputs a control signal Y.

The flow rate control valve SV of the actuation mechanism 90 receives the control signal Y
The aperture area of the diaphragm is changed according to the amount of pressure, and the hydraulic pressure of the accumulator AL is introduced into the actuator AC.
As a result, the pressure inside the cylinder of actuator AC is changed, the piston is moved, and the knuckle arm 13 is rotated around the fulcrum 13a. Since the left and right knuckle arms 13, 13 are connected by the steering linkage SL, the rotation of the knuckle arms 13, 13 causes the left and right rear wheels 1
2 and 12 are steered to generate a steering angle δ _r (t).
Note that, as a matter of course, the front wheels 6 are steered in accordance with the steering of the steering wheel 1, and a steering angle δ _f (t) is generated in the front wheels 6.
Further, it goes without saying that the steering direction of the handle 1 and the steering direction of the front wheels 6 are the same.

The relationship between the characteristics of the signal processing circuit and the steering angle δ _r (t) of the rear wheels 12 when operated as described above will be explained in detail based on FIGS. 8A, B, C, and D.

FIG. 8A shows the characteristics of the signal processing circuit 300 of this embodiment. The signal processing circuit 300 is
With respect to the input displacement signal D=D ₀・sinωt, the gain is always constant K _A , and as the angular frequency ω increases, the control signal Y whose phase is delayed from 0° to a maximum of 180° is output. . While the angular frequency ω of the displacement signal D is in the small region ω ₁ , the signal processing circuit outputs a signal obtained by multiplying the input signal by K _A as the control signal Y=K _A ·D due to the characteristics of the signal processing circuit. For this reason,
The rear wheels are steered by the actuating mechanism in response to the control signal Y, and the steering angle δ _r (t) of the rear wheels 12 is in the same direction as the steering angle δ _f (t) of the front wheels 6, as shown in FIG. 8B. controlled by. The steering angle of the rear wheels at this time is proportional to the displacement of the steering wheel.

On the other hand, while the angular frequency ω of the displacement signal D is in the large region ω ₃ , due to the characteristics of the signal processing circuit, the signal processing circuit outputs a signal whose phase is delayed by 180° with respect to the input signal, that is, the displacement signal _D. The multiplied signal is output as a control signal Y=-K _A.D. For this reason,
The rear wheels are steered by an actuating mechanism according to the control signal Y, and the steering angle δ _r (t) of the rear wheels 12 is equal to the steering angle δ _f (t) of the front wheels 6, as shown in FIG. 8D. In the opposite direction, it is controlled in a magnitude proportional to the displacement of the handle.

Furthermore, while the angular frequency ω of the displacement signal D is in the region ω ₂ between the region ω ₁ and the region ω ₃ , the signal processing circuit changes the phase from 0° to 180° with respect to the input signal due to the characteristics of the signal processing circuit. A signal with a delay of up to .degree. is output as a control signal Y. For example, if the signal processing circuit outputs a signal whose phase is delayed by 90 degrees with respect to the input signal as the control signal Y, the rear wheels are steered by the operating mechanism with a delay in relation to the front wheels, and as shown in FIG.
As shown in FIG. 1, the steering angle δ _r (t) of the rear wheels 12 is controlled to become zero at the time when the steering angle δ _f (t) of the front wheels reaches the maximum.

In the above, we have explained the case where the steering wheel is continuously steered in a sinusoidal manner as the effect of the second specific embodiment, but below we will explain the second example when a lane change is performed under the situation where the vehicle is actually driven. The operation of the specific embodiment will be explained with reference to FIGS. 9A, B, and C. Note that the effects shown in FIGS. 9A, B, and C are substantially the same not only in the second specific embodiment but also in the first specific embodiment, which shows the feasibility of the present invention.

9A, B, and C all show the rotational steering angle δ _h (t) of the steering wheel when changing lanes in a vehicle using the device related to the second specific embodiment.
This shows a waveform of the steering angle δ _r (t) of the rear wheels with respect to time. As shown in area a of FIG. 9A,
When the steering speed of the steering wheel is slowed down and the vehicle is steered to the right, the rear wheels are steered in the same direction as the steering wheel (in this case, from left to right). On the other hand, as shown in area c in Figure 9C, when the steering wheel is turned faster and steered from the right to the left, the rear wheels will move in the opposite direction to the direction in which the steering wheel is steered (this (from left to right steering direction). Moreover, as shown in area b of FIG. 9B,
When the steering wheel is steered at a speed intermediate between the above two, the rear wheels are steered with a delay in relation to the steering wheel, and as mentioned above, if the phase delay is approximately 90 degrees, the speed shown in Figure 9B is As shown at point d, when the steering angle of the steering wheel becomes maximum, the steering angle of the rear wheels becomes approximately zero. Since the direction of steering of the steering wheel is the same as the direction of steering of the front wheels, the device of this embodiment adjusts the steering angle of the rear wheels relative to the steering angle of the front wheels according to the steering speed of the steering wheel, that is, the angular frequency of steering of the steering wheel. It is understood that the direction and magnitude of are controlled.

As explained above, in the second specific embodiment, when the steering wheel is turned slowly, the rear wheels are steered in the same direction as the steering angle of the front wheels, and when the steering wheel is turned quickly, the rear wheels are steered in the same direction as the steering angle of the front wheels. Since the rear wheels are steered in the direction of , and the steering angle of the rear wheels is controlled, it has the advantage that both the running stability of the vehicle when traveling straight and the responsiveness of turning motion can be improved. In the second specific embodiment, the function of a determination circuit that determines the steering speed of the steering wheel by determining the steering speed of the steering wheel based on the angular frequency of the steering wheel;
The structure of the signal processing circuit is simplified because it uses a simple phase shift circuit and a coefficient multiplier that simultaneously performs both the control circuit function of outputting a control signal corresponding to the steering speed of the steering wheel. , suitable for in-vehicle use,
It has the advantage of Furthermore, the signal processing circuit of the second specific embodiment determines the steering speed of the steering wheel based on the angular frequency of steering the steering wheel, and as the angular frequency increases, the phase changes with respect to the input displacement signal. It is characterized by outputting a control signal that is delayed by up to 180 degrees and whose absolute value is amplified at a constant value regardless of the angular frequency of the steering wheel. The present invention is not limited to this circuit, and any circuit can be applied as long as it determines the steering speed of the steering wheel based on the angular frequency of steering the steering wheel based on the control calculation principle of the second aspect of the present invention. Furthermore, as for the operating mechanism of the second specific embodiment, as described in the operating mechanism of the first specific embodiment, if necessary, means for detecting the steering angle of the rear wheels may be provided as needed. The rear wheels may be steered by controlling the flow rate control valve by so-called feedback control, which uses a deviation signal between the output signal of the controller and the control signal from the signal processing circuit. Also, the second
In the specific embodiment, instead of detecting the circuit steering angle of the steering wheel, an example was described in which linear motion converted by a motion conversion mechanism such as a rack and pinion built in the gearbox is detected as the steering displacement of the steering wheel. For example, the rotational movement of the knuckle arm or the steering angle of the front wheels may be detected as the displacement.

In each of the specific embodiments described above, an example was explained in which a linear potentiometer or a rotary potentiometer was used as the detection means, but the present invention is not limited to this, and the present invention It is possible to use sensors such as electromagnetic sensors, optical sensors, and telemeters that detect changes in magnetic flux. The control means of the present invention is not limited to what is illustrated in each specific embodiment, but may be one that determines the steering speed of the steering wheel and outputs a signal corresponding to the steering speed of the steering wheel based on this determination. Any circuit, if any, can be used. Furthermore, although each specific embodiment has been shown as an example constructed using an analog circuit, the present invention is not limited thereto, and may also be constructed using a digital circuit using a microcomputer or the like. Further, the actuation mechanism of the present invention is not limited to those illustrated in each specific embodiment, but may be any mechanism as long as it generates force in response to a control signal output from the control means and controls the steering angle of the rear wheels. A hydraulic circuit, a pneumatic circuit, an air actuator, a hydraulic actuator, or an electromagnetic force or other force other than those described in each specific embodiment may be used to apply force to the rear wheel.

Although the first specific embodiment describes an example in which the steering angle of the rear wheels is controlled by detecting the rotational steering angle of the steering wheel, it is also possible to control the steering angle of the rear wheels by detecting the displacement of the steering wheel. In the second specific embodiment, an example has been described in which the steering angle of the rear wheels is controlled by detecting the displacement of the steering wheel, but it is also possible to control the steering angle of the rear wheels by detecting the rotational steering angle of the steering wheel. Therefore, in the first specific embodiment, the detection means of the second specific embodiment is used, and in the second specific embodiment, the detection means of the first specific embodiment is used.
It is also possible to use the detection means of the specific embodiments. In addition, in each specific example, the angular frequency ω
When the angular frequency ω is large, the amplifier becomes -K _A , and when the angular frequency ω is small, the amplification factor becomes K _A. Therefore, if the transfer function G(S) corresponding to equation (3) is shown, it becomes as follows.

G(S)=K _A −2K _A /1+TS・TS……(10)

[Brief explanation of drawings]

1 is a block diagram showing a basic embodiment of the present invention, FIG. 2 is a block diagram showing a conventional rear wheel steering angle control device for a four-wheel steering vehicle, and FIG. 3 is a first concrete embodiment of the present invention. The circuit diagrams illustrating the example, FIG. 4A and FIG. 4B, are the first sample-and-hold circuit output, the steering angle signal, the mono-multi circuit output, the differential amplifier circuit output, and the second sample-and-hold circuit output in the first specific embodiment. A diagram showing each waveform of the sample-and-hold circuit output and an oscillator output, FIG. 5 is a diagram showing the waveform of the absolute value circuit output of the first concrete example, and FIGS. A diagram showing the waveform of the comparison circuit output of a specific example,
FIG. 7 is a block diagram showing a second specific embodiment of the present invention, FIG. 8A is a diagram showing the gain and phase of the signal processing circuit of the second specific embodiment, FIGS. 8
Figures C and 8D are explanatory diagrams showing the steering angles of the front and rear wheels corresponding to Figure 8A, and Figures 9A, 9B and 9C are for the second specific embodiment. FIG. 4 is a diagram showing changes in the steering angle of the steering wheel and the steering angle of the rear wheels at the time of lane change. DESCRIPTION OF SYMBOLS 1... Handle, 2... Shaft, 6... Front wheel, 12... Rear wheel, 20... Detection means, 22...
Judgment circuit, 24... control circuit, 26... control means, 28... operating mechanism.

Claims (1)

[Claims] 1. A rear wheel rudder for a vehicle that automatically controls the rudder angle of the rear wheels in response to the steering of a steering wheel that controls an operating mechanism that creates a rudder angle in the rear wheels to create a rudder angle in the front wheels. In the angle control device, a detection means for detecting a steering amount of the steering wheel and outputting a steering amount signal, a determining means for determining a steering speed of the steering wheel based on the steering amount signal, and a determination by the determining means. Based on the results, when the steering speed is fast, the rear wheels are caused to produce a steering angle in the opposite direction to the front wheels, and when the steering speed is slow, the rear wheels are made to produce a steering angle in the same direction as the front wheels. A rear wheel steering angle control device for a vehicle, comprising: a control means for controlling the operating mechanism. 2. The control means causes the rear wheels to produce a steering angle in the opposite direction to the front wheels when the steering speed is high, and the steering speed is slow, based on the determination result of the determination means and the steering amount signal. Claim 1, wherein the actuating mechanism is controlled so that the rear wheels produce a steering angle in the same direction as the front wheels, and the rear wheels produce a steering angle of a magnitude corresponding to the steering amount signal. Rear wheel steering angle control device. 3. When the constants Kd and Ke are set to satisfy the condition 0<Kd<Ke, the complex frequency is S, and the first-order lag time constant is T, the judgment means is as follows: G(S)=Kd-Ke/1+TS・TS Judgment is made based on the transfer function G(S) expressed by
2. The rear wheel steering angle control device for a vehicle according to claim 1, wherein the control means controls the actuation mechanism based on the result of the determination.