JPS62157870A - Power steering device for vehicle - Google Patents

Abstract

PURPOSE:To improve steering stability of a vehicle, by compounding the first control quantity on the basis of steering force with the second control quantity on the basis of steering reaction force and obtaining a steering shaft rotation control signal which controls a steering shaft actuator rotating a steering shaft to be driven. CONSTITUTION:A device is equipped with the first control quantity determining means 9 which determines the first control quantity controlling rotation of a steering shaft 3 on the basis of an output of a steering force sensor 6. While the device is equipped with the second control quantity determining means 11 which determines the second control quantity rotating the steering shaft 3 in the resetting direction on the basis of a steering reaction force detection signal removing a component in a high frequency region from the output of a steering reaction force sensor 7 by a high frequency component removing means 10. And a steering shaft rotation control signal, being obtained by compounding the first and second control quantities by a steering shaft rotation control signal output means 12, controls a steering shaft actuator 4. While a target steering quantity is determined in a target steering quantity determining means 13 on the basis of an output from a steering displacement quantity sensor 8, and a steered wheel 2 is steered by a steering control means 5 in accordance with the value of said target steering quantity.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a steering device for a vehicle that steers steering wheels in accordance with the rotation of a steering wheel, and particularly relates to a steering shaft connected to a steering wheel. The present invention relates to a power steering system for a vehicle in which a steering mechanism for steering steering wheels is mechanically separated and the linkage thereof is replaced by an electrical control device.

[Prior art]

Conventionally, this type of technology has been disclosed in Japanese Utility Model Application Publication No. 51-19428 and Japanese Utility Model Application Publication No. 56-42469,
An angle sensor that electrically detects the rotation angle of the steering shaft and an electric control device that electrically controls the steering angle of the steering wheel steering mechanism based on the detected angle signal are installed, and the steering wheel is controlled by the rotation of the steering wheel. This eliminates the need for a coupling mechanism that mechanically connects the steering shaft and the steering wheel turning mechanism, and makes effective use of the space required for disposing the coupling mechanism.

[Problem that the invention seeks to solve]

However, in the conventional device described above, the coupling mechanism is simply replaced with an electric control device that controls the steering angle of the steering wheel steering mechanism to match the rotation angle of the steering shaft. Since the road reaction force received from the steering wheel is no longer transmitted to the steering wheel, the appropriate steering reaction force, steering reaction force, and restoring force of the steering wheel are not transmitted from the steering wheel to the steering wheel, resulting in poor vehicle steering performance. Become. Therefore, in the following patent application, the present applicant has proposed that the steering shaft be stopped at a position where the mutual forces are balanced based on the steering force applied to the steering wheel and the steering reaction force that the steering wheel receives from the road surface. By controlling the rotation and the turning angle of the steering wheels according to the rotation position of the steering shaft, the steering wheels can be turned according to the rotation of the steering wheel, and the steering wheels can be turned in accordance with the rotation of the steering wheel. We have proposed a power steering system for a vehicle in which a steering reaction force, a steering reaction force, and a restoring force of the steering wheel are generated in the steering wheel according to the turning reaction force.

Japanese Patent Application No. 60-133483 No. 152831 No. 60-178782 No. 186498 No. 1987 However, in the above proposed device, all the force transmitted from the road surface to the steering wheels is transferred. Detected as rudder reaction force,
A force based on the detected steering reaction force is applied to the steering wheel, so when the vehicle is traveling at a medium to high speed on a road with uneven road surfaces, the force that changes at a speed that the driver cannot react is applied to the road surface. When the force is transmitted from the force to the steering wheel, a force that changes at the speed described above is also applied to the steering wheel. As a result, the driver cannot operate the steering wheel in response to this force, the steering wheel is turned against the driver's inaction, and the steering wheels are accordingly turned against the driver's will. Because
The handling stability of the vehicle deteriorates.

That is, the proposed device has an advantage over the conventional device in that the driver can operate the steering wheel while feeling the steering reaction force transmitted from the road surface to the steered wheels. When a force that changes at a fast speed is transmitted from the road surface to the steering wheel, there is a drawback that the steering stability of the vehicle deteriorates.

The present invention improves the above-mentioned disadvantages without detracting from the above-mentioned advantages, and improves the steering stability of the vehicle even when forces that change at such a speed that the driver cannot react are transmitted from the road surface to the steered wheels. It is an object of the present invention to provide a power steering device for a vehicle that is maintained in good condition.

[Means for solving problems]

In order to solve this problem, the structural feature of the present invention is as shown in FIG. A coupled steering shaft 3, a steering shaft actuator 4 that rotationally drives the steering shaft 3, a steering control means 5 that is coupled to the steering wheel 2 and steers the wheel 2, and a steering shaft actuator 4 that rotates the steering shaft 3, a steering control means 5 that is coupled to the steering wheel 2 and steers the wheel 2, and a steering shaft actuator 4 that rotates the steering shaft 3. a steering force sensor 6 that detects the steering force applied to the steering force and outputs a steering force detection signal representing the detected steering force;
a steering reaction force sensor 7 that detects the steering reaction force applied to the steering control means 5 from the steering wheel 2 and outputs a steering reaction force detection signal without indicating the detected steering reaction force; a steering displacement amount sensor 8 that detects the rotation angle of the steering shaft 3 from a reference position as a steering displacement amount and outputs a steering displacement amount detection signal representing the detected steering displacement amount; a first control amount determining means 9 for determining a first control amount that increases in accordance with an increase in steering force and rotates the steering shaft 3 in the direction in which the steering force is applied; a high-frequency component removing means 10 for removing frequency components in a high frequency region from among the frequency components to be detected; and a cough high-frequency component removing means 10.
Based on the turning reaction force detection signal from which components in a higher frequency range have been removed, the steering shaft 3 is rotated in a direction in which the steering shaft 3 is increased in accordance with an increase in the detected turning reaction force and returns the steering shaft 3 to the reference position. a second control amount determination means 11 that determines a second control amount; and outputs a steering shaft rotation control signal, which is a combination of the first control amount and the second control amount, to the steering shaft actuator 4 to rotate the steering shaft 3. and a steering shaft rotation control signal output means 12 for controlling the steering wheel 2, which increases in accordance with an increase in the detected steering displacement amount based on the steering displacement amount detection signal and in a direction corresponding to the steering direction of the steering handle 1. and outputs a steering control signal corresponding to the determined target steering amount to the steering control means 5 to determine a target steering amount for steering the steered wheels 2. Is the steering control so that the amount of steering becomes the determined target amount of steering? ] (2) A steering control signal output means 14 for controlling the means 5 is provided.

[Action of the invention]

In the present invention configured as described above, when the driver attempts to turn the steering wheel 1 to turn the vehicle, the steering force is transmitted from the steering wheel 1 to the steering shaft 2 coupled to the steering wheel l. Ru. The steering force sensor 6 detects this steering force and outputs a steering force detection signal, and based on this steering force detection signal, the first control amount determining hand 9 rotates the steering shaft 3 in the direction in which the steering force is applied. The first control amount is used to control the steering shaft rotation control signal output means 1.
2 outputs a steering shaft rotation control signal to the steering shaft actuator 4, and the steering shaft actuator 4 rotates the steering shaft 3 in the direction in which the steering force is applied.

The steering displacement amount sensor 8 detects the rotation angle of the steering shaft 3 from the reference position as the amount of steering displacement, outputs a steering displacement amount detection signal, and based on this steering displacement amount detection signal, the target turning amount determining means 13 Since the steering control signal output means 14 and the steering control means 5 steer the steering wheel 2, the steering wheel 2 is steered in accordance with the turning operation of the steering handle 1. At this time, the steering wheels 2 receive a steering reaction force from the road surface in a direction opposite to the steering direction. The steering reaction force sensor 7 detects this steering reaction force and outputs a steering reaction force detection signal, and the high-frequency component removing means lO detects a high frequency among the frequency components included in this steering reaction force detection signal. Remove frequency components in the region. Based on this steering reaction force detection signal from which high frequency components have been removed, the second
The control amount determining means 11 determines a second control amount for rotating the steering shaft 3 in a direction to return it to the reference position, and the steering shaft rotation control signal output means 12 determines a first control amount for rotating the steering shaft 3 in opposite directions. Since the steering shaft rotation control signal which is a combination of the control amount and the second control amount is output to the steering shaft actuator 4,
The steering shaft actuator 4 controls the rotation of the steering shaft 3 so that the first control amount and the second control amount match. As a result, when the first control amount is larger than the second control amount, the steering shaft rotation control signal output means 12 and the steering shaft actuator 4 move the steering shaft 3 in the direction in which the steering force is applied with a force corresponding to the difference between them. When the first controlled variable is smaller than the second controlled variable, the steering shaft 3 is rotated in a direction that returns the steering shaft 3 to the reference position with a force corresponding to the difference between them, and when the first controlled variable is equal to the second controlled variable. The steering shaft 3 is made stationary.

〔Effect of the invention〕

In this way, the second control amount based on the steering reaction force acts on the first control amount based on the steering force so as to rotate the steering wheel @3 in the opposite direction to the direction in which the steering force is applied. Therefore, a steering reaction force, a steering reaction force, and a restoring force of the steering handle 1 corresponding to the turning reaction force that the steering wheel 2 receives from the road surface are generated on the steering handle 1 connected to the steering shaft 3. Since the driver can drive the vehicle while feeling these forces as a steering sensation, the steering stability of the vehicle is improved.

Furthermore, since the high-frequency component removing means 10 removes the frequency components in the high frequency range included in the steering reaction force detection signal, the changes occur at such a speed that the driver cannot react, which is the cause of the generation of these frequency components. The steering reaction force that changes at such a speed no longer affects the second control amount, and the steering reaction force that changes at the above-mentioned speed is no longer transmitted to the steering wheel 1. This prevents the steering wheel 1 from being turned against the driver's negligence, and at the same time prevents the steering wheel 2 from being turned against the driver's will, so the proposed device is adopted. The steering stability of the vehicle is improved compared to existing vehicles in which the steering wheel is mechanically connected to the steering wheel so that all the steering reaction force is transmitted to the steering wheel.

〔Example〕

a. Basic Configuration The basic configuration of an embodiment of the present invention in which the left and right front and rear wheels are all independently steered by the vehicle power steering device according to the present invention will be described below with reference to the drawings.

FIG. 2 shows a mask part A operated by the driver, a first slave part B1 that steers the left front wheel, a second slave part B2 that steers the right front wheel, and a third slave part B2 that steers the left rear wheel. Slave part B3
A power steering system for a vehicle is comprised of a fourth slave section B4 that steers the right rear wheel, and an electric control device C that electrically controls the mask section A and the first slave section B1 to fourth slave section B4. An outline is shown.

The mask portion A is connected to the steering shaft 2 fixed to the steering handle 20.
1, and a steering shaft motor 22 which is provided at the lower end of the coaxial shaft 21 and rotates the steering shaft 21. A steering displacement amount sensor 23 that generates a signal representing a steering displacement amount Ym proportional to the angle, and a steering handle 20
It consists of a strain gauge that detects the amount of torsion generated in the steering shaft 21 in proportion to the steering force Fm applied to the steering shaft 21 from
A steering force sensor 24 is attached that generates a signal representing the steering force Fm. In this case, when the steering wheel 20 and the steering shaft 21 rotate to the left (or right), the steering force Fm
and deep rudder displacement fil Y m are each positive (or negative).

The first slave section Bl is engaged with a left front wheel steering shaft motor 30 whose rotation is controlled by an electric control device C, a left front wheel steering shaft 32 connected at one end by the motor 30 and having a pinion 31 at the other end, and the pinion 31. A rank shaft 34 is provided to control the steering of the left front wheel 33. The rack shaft 34 connects to the left front wheel 3 via a tie rod 35 and a knuckle arm 36.
3, and the left front wheel 33 is steered by the reciprocating motion of the coaxial shaft 34 in the lateral direction of the vehicle body. The left front wheel steering shaft 32 includes
a left front wheel steering displacement amount sensor 37 that detects the rotation angle of the coaxial shaft 32 from a reference position by the left front wheel steering shaft motor 30 and generates a signal representing a left front wheel steering displacement amount Ysfl proportional to the rotation angle; and a left front wheel 33 The left front wheel steering shaft 32 is proportional to the left front wheel steering reaction force Fsfl applied to the left front wheel steering shaft 32 from
A left front wheel steering reaction force sensor 38 is installed, which is made up of a strain gauge that detects the amount of twist occurring in the steering wheel, and generates a signal representing the left front wheel steering reaction force Fsfl.

The second slave part B2 is configured in the same manner as the first slave part B1, and has a right front wheel steering shaft motor 40, a pinion 41, a right front wheel steering shaft 42, and a right front wheel 43, which correspond to each component of the first slave part B1. , rack shaft 44, tie rod 45,
It includes a knuckle arm 46, a front right wheel steering displacement sensor 47, and a front right wheel steering reaction force sensor 48. The right front wheel steering displacement amount sensor 47 generates a signal representing the right front wheel steering displacement amount Ysf2 proportional to the rotation angle of the right front wheel steering shaft 42 from the reference position, and the right front wheel steering reaction force sensor 48 generates a signal representing the right front wheel steering displacement amount Ysf2 proportional to the rotation angle of the right front wheel steering shaft 42 from the reference position.
A signal representing the front right wheel steering reaction force FS "2" is generated.

In addition, the third slave section B3 and the fourth slave section B4 are also
Left and right rear wheel steering shaft motors 50, 60, pinions 51° 61, and left and right rear wheel steering shafts 52, which are configured similarly to the first slave section B1 and correspond to each component of the first slave section B1, respectively.
, 62, left and right rear wheels 53° 63, rack shafts 54, 64, quirods 55, 65, knuckle arms 56, 66, left and right rear wheel steering displacement amount sensors 57, 67, and left and right rear wheel steering reaction force sensors 58, 68. ing. The left and right rear wheel steering displacement amount sensors 57 and 67 measure the left and right rear wheel steering displacement amount Ysr proportional to the rotation angle from the reference position of the left and right rear wheel steering shafts 52 and 62, respectively.
The left and right rear wheel steering reaction force sensors 58 and 68 generate signals representing left and right rear wheel steering reaction forces Fsrl and Fsr2 applied to the left and right rear wheel steering shafts 52 and 62, respectively.

In addition, in these cases, each steering shaft 32, 42, 52.62
rotates to the right (or left), and each rack axis rotates 34°44.54.
64 is displaced in the left (or right) direction.

When each wheel 33.43, 53.63 is steered in the left (or right) direction, each steering displacement amount Ysfl.

Ysf2. Ysrl, Ysr'l and each steering reaction force Fsf
l, Fsf2. Fsrl and Fsr2 are each positive (or negative)
becomes.

The electric control device C is connected to the steering displacement amount sensor 23 and multiplies the steering displacement amount Ym by each coefficient Kmpf, Kmpr to obtain the front wheel target turning amount Kmpf-Ym and the rear wheel target turning amount! tKm
Front wheel target steering amount calculator 70 that calculates p r-Ym respectively
and rear wheel target steering amount calculator 71, and F? fA rudder deflection sensor 24 is connected to a steering force calculator 72 which calculates a control amount Kmf-Fm by multiplying the steering force Fm by a coefficient Kmf, and is connected to each steering displacement amount sensor 37, 47, 57, 67, respectively. Rudder displacement IYs f 1. Ys f 2. Ys r
1+ Ysr2 each coefficient Kspf, Kspf, Ksp
Each control iKs p f−Ys f multiplied by r and Kspr
1. Kspf-Ysf2', Kspr-Ysrl
, Kspr-Ysr2, respectively, a left front wheel steering displacement amount calculator 73, a right front wheel steering displacement amount calculator 74, a left rear wheel steering displacement amount calculator 75, and a right rear wheel steering displacement amount calculator 76.
A control signal for controlling the rotation of the steering shaft 21 is sent to the steering shaft motor 2.
a steering shaft morph control circuit 77 that outputs to each motor 3o, 40, 50, 60 a steering shaft morph control circuit 77 that outputs each control signal to each motor 3o, 40, 50, 60, and a left front wheel steering shaft motor that outputs each control signal that controls the rotation of the steering shaft 32, 42, 52, 62, respectively to each motor 3o, 40, 50, 60; It includes a control circuit 78, a right front wheel steered shaft motor control circuit 79, a left rear wheel steered shaft motor control circuit 8o, and a right rear wheel steered shaft motor control circuit 81. The steering shaft motor control circuit 77 controls iKmf from the steering force calculator 72.
-Fm, and each steering reaction force Fsfl, Fsf2. from each steering reaction force sensor 38°48.58.68. Fsrl, Fsr
2 as table t Among the frequency components included in each signal, the low-pass filter 82a.

Each steering reaction force Fsfl* represented by each signal from which frequency components in a high frequency range, for example, approximately 1 to 10 Hz or more are removed by 82b, 82c, and 82d.
, Fsf2*, Fsrl*.

Control 11Ks f f ・(Fs
f1*+Fsf2*)+Ksfr・(Fsrl*+
Rotation control iMm that inputs Fsr2*) and rotates the steering shaft 21 to the left (or right) when the value is positive (or negative).
=Km f −Fm −K s f f −(F s
f1*+Fsf2*) −Ksfr・ (Fsrl*+
Fsr2*) is output. This control'f
f1lKs f f −(Fs r l*+Fs f
2*) +Ksfr・ (Fsrl**)'sr2*)
is supplied from the adder 83, and this adder 83
is a composite front wheel steering reaction obtained by adding the left and right front wheel steering reaction forces Fsfl* and Fsf2* output from the left and right front wheel steering reaction force sensors 38 and 48 via low-pass filters 82a and 82b, respectively, by an adder 84. Output Ksf of front wheel steering reaction force calculator 85 that multiplies force Fsfl*+Fsr2* by coefficient Fsff
f-(Fsfl*+Fsf2*) and the left and right rear wheel steering reaction force sensors 58°68 to low-pass filters 82C, 82d
The left and right rear wheel steering reaction forces Fsrl* are respectively outputted via the left and right rear wheel steering reaction forces Fsrl*.

The output of the rear wheel steering reaction force calculator 87 which multiplies the composite rear wheel steering reaction force Fsrl*+Fsr2* obtained by adding Fsr2* by the adder 86 by the coefficient Ksfr.
+Fsr2*) and control WkKsff-(F
sfl*+Fsf2*)+Ksf r ・(Fs r
l*+Fs r2*) is calculated.

The left front wheel turning shaft motor control circuit 7 inputs the control lKmpf-Ym from the front wheel target turning amount calculator 70 and the control amount Kspf·YSfl from the left front wheel turning displacement amount calculator 73, and calculates the value. Rotation control that rotates the left front wheel steering shaft 32 to the right (or left) when positive (or negative) JiMs f 1 =
A control signal representing Kmp f - Ym - K sp f ·Ysfl is output. Right front wheel steering shaft motor control circuit 7
9 is a control amount Kmpf from the front wheel target steering amount calculator 70.
−Ym and the control amount Ks from the right front wheel steering position calculator 74
pf - Ysf2 is input, and when the value is positive (or negative), the rotation control amount Msf2 for rotating the right front wheel steering shaft 42 to the right (or left) = Krnpf - Ym - Kspf ・Ysf
Outputs a control signal representing 2. The left rear wheel turning shaft motor control circuit 80 receives the control amount K from the rear wheel target turning amount calculator 71.
mpr-Ym and the control amount Kspr-Ysrl from the left rear wheel steering displacement amount calculator 75 are input, and when the value is positive (or negative), the left rear wheel steering shaft 52 is rotated to the right (or left). Rotation control amount Msrl=Kmpr-Ym-Kspr-Ys
Outputs a control signal representing rl.

The right rear wheel turning shaft motor control circuit 81 calculates the control amount Kmpr-Ym from the rear wheel target turning amount calculator 71 and the control amount Kmpr-Ym from the right rear wheel turning displacement amount calculator 76) (apr・Ys "2"). input, and if the value is positive (or negative), the right rear wheel steering shaft 62
Rotation control amount Msr2 = Kmp to rotate clockwise (or counterclockwise)
A control signal representing r-Ym-Kspr·Ysr2 is output.

Note that the coefficient Kmf, the coefficient Ksff, and the coefficient Ksfr are as follows:
Steering force Fm, composite front wheel steering reaction force FsfL*+Fs f
2* and the composite rear wheel steering reaction force Fs r l *- +Fsr2* respectively indicate the degree of Yv brought to the rotational torque of the steering shaft 21, and the coefficient Kmf and the coefficient Ks
ff is always positive, and the coefficient KSrr is the left and right rear wheels 53.
63 becomes positive when the left and right front wheels 33.43 are steered in the same phase, and becomes negative when the left and right rear wheels 53.63 are steered in the opposite phase to the left and right front wheels 33.43. Also, the coefficient Kmp
f and the coefficient Kspf are the steering displacement amount Ym and the left and right front wheel turning displacement amounts Ysfl and Ysf2, respectively, at the left and right front wheel turning shafts 32.
The coefficient Kmp f and the coefficient Kspf are both positive. Furthermore, the coefficient Kmpr and the coefficient Kspr indicate the degree of influence that the steering displacement amount Ym and the left and right rear wheel turning displacement amounts Ysrl and Ysr2 respectively have on the rotation angle of the left and right rear wheel turning shafts 52 and 62, and the coefficient Kspr is always positive. It is. In addition, the coefficient Kmpr is 53.63 for the left and right rear wheels and 33.43 for the left and right front wheels.
It becomes positive when the wheels are steered in the same phase as the left and right rear wheels 53.
63 becomes negative when the left and right front wheels 33 and 43 are steered in the opposite phase.

The operation of the power steering device configured as described above is determined by a coefficient of 1<
To explain the case where mpr and the coefficient Ksfr are set to positive, when the steering wheel 20 is turned in the left (or right) direction by the rotation angle Xm while the vehicle is traveling straight, the steering wheel 20 starts turning. Sometimes the steering shaft motor 2
2 does not rotate the steering shaft 21, that is, the steering shaft 2
1 is at the reference position, the steering shaft 21 is twisted by rotation of the steering handle 20. This torsion of the steering shaft 21 is detected by a steering force sensor 24 consisting of a strain gauge, and is supplied to a steering force calculator 72 as a steering force (or a steering reaction force as a reaction) Fm. Steering force calculator 72
is the control amount Kmf - Fm, which is the steering force Fm multiplied by the coefficient Kmf
is output to the steering shaft motor control circuit 77. The steering shaft motor control circuit 77 uses the control amount Kmf-Fm inputted from the steering force calculator 72 and the control amount 1Ks inputted from the adder 83.
(C・(Fsfl++Fsf2*)+Ksfr・(
Rotation control of the steering shaft 21 based on Fsrl*+Fsr2*) JiMm=Kmf −Fm−Ks f f −(F
s f 1*+Fs [2*) −Ks f
A control signal representing r・(Fsrllk+Fsr2*) is output, but at the start of rotation of the steering wheel 200, the composite front wheel and steering reaction force Fs of the left and right front wheel steering shafts 32 and 42 is output.
Since the synthetic rear wheel steering reaction force Fsrl*+Fsr2* of fl*+Fsf2* and the left and right rear wheel steering shafts 52°62 is zero, the steering shaft motor 22 has a rotation control function iiMm of the steering shaft 21.
A control signal representing =Kmf·Fm is supplied. In response to this control signal, the steering shaft motor 22 rotates the steering shaft 21 in the left (or right) direction, so that the steering shaft 21 begins to rotate in the rotation direction of the steering handle 20.

Due to this rotation, the steering shaft 2 from the steering displacement amount sensor 23
The detected steering displacement amount Ym of 1 is input to the front wheel target turning amount calculator 70, and the front wheel target turning amount calculator 70 calculates the coefficient Kmp(
The control amount Kmpf-Y is obtained by multiplying the detected steering displacement amount Ym by
m is output to the left and right front wheel steering shaft motor control circuits 18 and 19, respectively. At this time, each steering displacement amount Ys f 1. of the left and right front wheel steering shafts 32, 42. Since Ys f 2 is zero,
The left and right front wheel steering shaft morph control circuits 78.79 each control the rotation amount of the left and right front wheel steering shafts 32.42 Ms r 1=Kmp
A control signal representing f・Ym, Ms r 2=Kmp f−Ym is output to the left and right front wheel steering shaft motors 30 and 40, respectively, and the left and right front wheel steering shaft motors 30 and 40 control the left and right front wheel steering shaft 3.
2 and 42 in the right (or left) direction. This rotation allows left and right front wheels to be steered! The respective left and right front wheel turning displacements 1Ysf1 and Ysr2 accompanying each rotation of 1b32°42 each become larger (or smaller) than zero, and the left and right front wheel turning displacement amount calculators 73 and 74 calculate the left and right front wheel turning displacement amounts Ysfl.
, each control amount Ksp obtained by multiplying Ysf2 by the coefficient Kspf.
f-Ysf1 and Kspf-Ysr2 are respectively output to the left and right front wheel steering shaft motor control circuits 78 and 79, and these control amounts Kspf-Ysf1. Kspf-Ysr2 is each left and right front wheel steering displacement amount Ysf1. Each increase (or decrease) in Ysf2
Accordingly, each rotation control amount Ms f 1-K of the left and right front wheel steering shafts 32.42 gradually increases (decreases).
mp f ・Ym−Ksp f−Ysfl, Msf2=
The positive (or negative) level of the control signal representing Kmpf - Ym - Kspf - Ysr2 gradually becomes smaller, and the respective steering displacement amounts YSfl, Ys of the left and right front wheel steering shafts 32, 42
f2 is Ysf 1 =Kmp f-Ym/Ks p
f, Ys f2=Kmp f-Ym/Ks p
The left and right front wheel steering shafts 32, 4 at the rotational position where the relationship of f
Each rotation of 2 is stopped. These left and right front wheel steering shafts 32,
Each right (or left) rotation of 42 is transmitted to the rack shaft 34.44 via the pinion 31.41, respectively, and the rack shaft 34
44 in the left (or right) direction. The displacement of the rank shaft 34.44 in the individual (or right) direction is transmitted to the left and right front wheels 33.43 via the tie rods 35.45 and knuckle arms 36°46, respectively, and the left and right front wheels 33.4
3 to the left (or right) direction.

Further, the detected steering displacement amount Ym of the steering shaft 21 from the steering displacement amount sensor 23 is also inputted to the rear wheel target turning amount calculator 71, and the rear wheel target turning amount calculator 71 calculates the coefficient Kmpr as described above. The control amount Kmpr-Ym multiplied by the steering displacement amount Ym is output to the left and right rear wheel turning shaft motor control circuits 80 and 81, respectively. At this time, since the respective steering displacement amounts Ysr1°Ysr2 of the left and right rear wheel steered shafts 52, 62 are zero, the left and right rear wheel steered shaft motor control circuits 80.81 control the left and right rear wheel steered shafts 52, 62.
2 each rotation control amount Ms r 1 = Kmp r 'Y
m, Msr2=Kmpr-Ym are outputted to the left and right rear wheel steered shaft motors 50 and 60, respectively, and the left and right rear wheel steered shaft motors 50 and 60 respectively represent the left and right rear wheel steered shafts 52 and 62.
Start rotating each to the right (or left). Due to these rotations, the respective left and right rear wheel turning displacement amounts Ysr1 and Ysr2 accompanying each rotation of the left and right rear wheel turning shafts 52°62 become larger (or smaller) than zero, and the left and right rear wheel turning displacement amount calculator 75. 76 is each left and right rear wheel steering displacement amount Ysrl, Ys
Each control amount Kspr-Y is obtained by multiplying r2 by the coefficient Kapr.
sr1 and Kspr-Ysr2 are output to the left and right rear wheel steering shaft motor control circuits 80 and 81 respectively, and these control amounts Ksp
r-Ysrl and Kspr/Ysr2 are the left and right rear wheel steering displacements iYs r 1. Increase (or decrease) in Ys r 2
Accordingly, each rotation control amount Msrl of the left and right rear wheel steering shafts 52, 62 becomes thicker (or smaller).
r-Ym-Kspr-Ysr 1. Ms r 2=K
The positive (or negative) level of each control signal representing mp r - Ym - Ks pr - Ysr2 gradually becomes smaller, and each turning displacement amount Ysrl of the left and right rear wheel turning shaft 52°62,
Ysr2 is each Ysrl=Kmpr-Ym/Kspr,
The rotations of the left and right rear wheel steering shafts 52, 62 are stopped at each rotational position where the relationship Ysr2=Kmpr-Ym/Kspr is established. These left and right rear wheel steering shafts 52,
Each right (or left) rotation of 62 is transmitted to the rack shaft 54.64 through the pinion 51.61, respectively, displacing the rack shaft 54.64 in the left (or right) direction, respectively. The displacement of the rack shaft 54.64 in the individual (or right) direction is transmitted to the left and right rear wheels 53.63 via tie rods 55.65 and knuckle arms 56.66, respectively.
3 to the left (or right) direction.

On the other hand, the left and right front wheels 33.43 receive left and right front wheel steering reaction forces Fsfl and Fsf2 from the road surface in the right (or left) direction due to steering in the individual (or right) direction, and these left and right front wheel steering reactions are The forces Fsrl and Fsf2 are applied to the knuckle arm 36,
46, tie mouth/throat 35° 45, left and right front wheel steering shafts 32, 4 via rack shaft 34, 44 and pinions 31, 41
2, respectively. These left and right front wheel steering reaction forces Fsf
l, Fsf2 respectively move the left and right front wheel steering axes 32.42 to the left (
or to the right), so the left and right front wheel steering shaft motors 30, 40 rotate the left and right front wheel steering shafts 32, 42.
The directions are opposite to the forces that rotate the left and right front wheel steering shafts 32, 42, respectively, and twisting occurs in each of the left and right front wheel steering shafts 32, 42. These torsions are detected by the left and right front wheel steering reaction force sensors 38 and 48, each of which is a strain gauge. Detection signals representing wheel steering force) Fsfl and Fsf2 are output respectively. These detection signals are each passed through a low pass filter 8.
2a and 82b, and the same filters 82a and 82b remove frequency components in a high frequency region, for example, approximately 1 to 10 Hz or higher, from among the frequency components included in these detection signals. Each left and right front wheel steering reaction force Fs f 1 *, Fs f expressed by the signal
2* is supplied to a front wheel steering reaction force calculator 85 via an adder 84.

The front wheel steering reaction force calculator 85 calculates the combined front wheel steering reaction force (steering force) Fsfl*+Fsf2* synthesized by the adder 84.
control fiKsf f' (F
s f 1 *+l"s'f 2 *) is output to the adder 83.

In addition, the left and right rear wheels 53.63 receive left and right rear wheel steering reaction forces Fsrl and Fsr2 from the road surface in the right (or left) direction due to steering in the respective (or right) directions, and these rear wheels are steered. The reaction forces Fsrl and Fsr2 are 1. Knuckle arm 5 each
6, 66, tie rod 55.65, rack shaft 54.64
and left and right rear wheel steering shafts 52. through binions 51.61.
62 in the left (or right) direction, the left and right rear wheel steering shaft motors 50, 60 rotate the left and right rear wheel steering shafts 52, 62 in the opposite direction, and the left and right rear wheel steering shafts are rotated in the opposite direction. Each of the shafts 52 and 62 is twisted. These torsions are detected by left and right rear wheel steering reaction force sensors 58 and 68 each consisting of a strain gauge;
outputs detection signals representing left and right rear wheel steering reaction forces (or rear wheel steering forces as reactions) Fsrl and Fsf2, respectively, which are proportional to each twist amount. These detection signals are supplied to low pass filters 82c and 82d, respectively.
c and 82d are the left and right signals represented by the signals from which frequency components in the high frequency range, for example 1 to 10 hertz or higher, are removed from among the frequency components included in these detection signals. Rear wheel steering reaction force Fsrl*, Fs
r2* is supplied to a rear wheel steering reaction force calculator 87 via an adder 86. The rear wheel steering reaction force calculator 87 calculates the combined rear wheel steering reaction force (rear wheel steering force) FSrl synthesized by the adder 86.
Control 1tKs obtained by multiplying *+Fsr2* by the coefficient Ksfr
f r -(Fs r 1*+Fs r2*) is output to the adder 83.

Then, the adder 83 receives the control ff1Ks f f from the front wheel steering reaction force calculator 85 (Fs f 1*+Fs f
2*) and the control amount Ks from the rear wheel steering reaction force calculator 87
ft・(Fsrl*+Fsr2*) is added and synthesized,
Synthetic shift control amount Ksfr-(Fsfl*+Fsf2*)
+Ksfr·(Fsrl*+Fsr2*) is output to the steering shaft motor control circuit 77.

The steering shaft motor control circuit 77 calculates the control amount Kmf−Fm input from the steering force calculator 72 and the control amount Ksff・(Fsfl*+Fsf2*)+K input from the adder 83.
Based on sfr・(Fsrl*+Fsr2*), the rotation control amount Mm of the steering shaft 21=Kmf−Fm−Ksf f
・(Fsf 1*+Fsf2'l')-Ksfr・
A control signal representing (Fsrl*+Fsr2*) is output to the steering shaft motor 22, and the steering shaft motor 22 controls the rotation of the steering shaft 21 based on this control signal. In this rotational movement of the steering shaft 21 in the left (or right) direction, the control amount K
mf and Fm act to rotate the steering shaft 21 in the left (or right) direction, and when the steering shaft 21 rotates in the left (or right) direction, the amount of twist of the steering shaft 21 decreases, so this amount of twist Steering force (steering reaction force) proportional to Fs, each left and right front wheel turning reaction force (steering force) applied to 43, Fsfl, Fsf2, and each left and right rear wheel turning reaction force applied to left and right rear wheels 53.63 (Rear wheel steering force) Fsrl and Fsr2 are each left and right front wheel steering displacement amount Ys [1, Ysf2 and each left and right rear wheel steering displacement amount Ys
As r1 and Ysr2 each increase (or decrease), they become larger (or smaller), so the control amount Ksff that acts to rotate the steering shaft 21 in the right (or left) direction.
(Fsfl*+Fsf2*)+Ksfr-(Fsrl
*+Fsr2*) becomes larger (or smaller). As a result, the rotation control amount Mm for rotating the steering shaft 21 to the left (or right) = Kmf - Fm - Ksff (Fsfl*
+Fsf2*)-Ksrr-(Fsrl*'+Fsr2
*) gradually becomes smaller (or larger), and the control amount Km
f-Fm and ff1ll? 311EtKs f f ・(
Fs f 1 *+Fs r 2*)+Ksfr-(F
The rotation of the steering shaft 21 stops at the rotational position where srl*+Fsr2*) becomes equal.

In this state, when the driver further applies a force in the left (or right) rotation direction to the steering wheel 20 in order to further rotate the steering wheel 20 left (or right), the control amount K
mf−Fm is the control amount Ksff・(Fsfl*+Fsf
2*)+Ksfr-(Fsrl*+Fsr2*), and the steering shaft 21 further rotates to the left (or right).
When the force applied to is weakened, the control 1iKsff・(Fs
fl*+Fsf2*)+Ksfr・ (Fsrl'l'
+p'sr2*) becomes larger (or smaller) than the control amount Kmf-Fm, and the steering shaft 21 begins to rotate in the right (or left) direction.

Furthermore, a case will be described in which the coefficient pCmp r and the coefficient Ksfr are set to negative values. When the steering wheel 20 is turned to the left (or right), the left and right front wheels 33, 43 are steered to the left (or right) as in the case described above.
The left and right rear wheels 53.63 have a negative coefficient Kmpr, so contrary to the above case, the right (or left) direction, that is, the left and right front wheels 33
．． It is steered in the opposite phase to 43. Due to this steering, each left and right rear wheel steering reaction force Fsrl, F
sr2 will work in the opposite direction to the above case,
The left and right rear wheel steering reaction forces Fsrl*, Fsr2* have opposite signs to those in the above case, but since the coefficient Ksfr is set to negative, each control amount Ksfr−Fsrl(Ks
The positive and negative signs of fr-Fsr2* are the same as in the above case, and each control amount Ksfr-Fsrl*, Ksfr-Fsr
2* acts to rotate the steering shaft 21 in the right (or left) direction as in the above case.

In this way, when the driver rotates the steering wheel 20, when the driver holds the steering wheel 20 in the rotational position, and when the driver returns the steering wheel 20 to the neutral position, the left and right front wheel steering reaction force Fsfl.

Fsf2 and left and right rear wheel steering reaction force Fsrl, control amount Ksfr・(Fsfl*+Fsf2*) based on Fsr2
+Ksfr (Fsrl*+Fsr2*) acts to return the steering wheel 20 to the neutral position, so
The steering handle 20 has left and right front wheel steering reaction forces Fsfl and Fs.
A steering reaction force, a steering reaction force, and a restoring force of the steering handle 20 are applied according to f2, left and right rear wheel steering reaction forces Fsrl, and Fsr2.

Furthermore, when a steering reaction force that changes at a speed that the driver cannot react to is applied to each wheel 33, 43, 53, 63 from the road surface, each low-pass filter 82a.

Since adders 82b, 82c, and 82d remove high frequency component detection signals generated from each steering reaction force sensor 38, 48, and 58.68 based on the steering reaction force, adder 84.8
5 indicates each steering reaction force Fsf1*, Fsf'l*, Fsrl* expressed by a detection signal that does not include high frequency components.
, Fsr2'l' are supplied. As a result, the control 1Ksff・(F
sfl*+Fsf2*)+Ksfr・ (Fsrl*+
Fsr2*) is not affected by the steering reaction force applied from the road surface to each wheel 33, 43, 53.
Then, the turning reaction force is no longer transmitted as a steering reaction force, a steering reaction force, and a restoring force of the steering handle 20.

b. Determination of variables and their meanings Before explaining the specific embodiments of the present invention shown in the above basic structure, the coefficients Kmf, Ks f of the above basic structure
f, Ks f r, Kmp f, Kmp r.

The calculation method and properties of Kspf, Kspr, and various variables calculated in specific embodiments will be explained with reference to the drawings. FIG. 3 shows the basic configuration of the present invention shown in FIG. .

It is a control block diagram showing the portion excluding 82c and 82d as an equivalent circuit. Note that, as described later, low-pass filters 82 a, 82 b, 82 c, 82
Each of the above coefficients Km is calculated based on the control block diagram in which d is omitted.
f, Ks f f, Ks f r, Kmp f,
Even if Kmpr, Kspf, and Kspr are calculated, these coefficients are originally based on the master part A and the first to fourth sleeve parts B1. B2. B3.84 shows the force transfer characteristics between the low-pass filters 82a, 82b, 8
Since it is related to the signal passing through 2c and 82d,
There's no problem.

Multipliers 70a, 71a, 72a, 73a, ? 4a,
75 a, 76 a, 85 a, 87 a
are the front wheel target turning amount calculator 70, the rear wheel target turning amount calculator 71, the steering force calculator 72, and the left front wheel turning displacement amount calculator 7, respectively.
3. Corresponds to the right front wheel steering displacement amount calculator 74, the left rear wheel steering displacement amount calculator 75, the right rear wheel steering displacement amount calculator 76, the front wheel steering reaction force calculator 85, and the rear wheel turning reaction force calculator 87. What shows their multiplication action and subtraction? ? a, 78a, 7
9a, 80a, and 81a are respective steering shaft motor control circuits 77;
, left front wheel steering shaft morph control circuit 78. Right front wheel steering shaft motor control circuit 79. Left rear wheel steering shaft motor control circuit 80. and the right rear wheel steering shaft motor control circuit 81, and show their subtractive actions, and the adders 83a, 84a, 86a
correspond to adders 83, 84, and 86, respectively.

Also, blocks 22a and 30a.

40a, 50a, and 60a correspond to the steering shaft motor 22°, the left front wheel steering shaft motor 30, the right front wheel steering shaft motor 40, the left rear wheel steering shaft motor 50, and the right rear wheel steering shaft motor 60, and have a function K. m/s.

Ks f/S, Ks f/S, Ks r/S, Ks r
/S indicates the rotational characteristics of the motors 22.30, 40, and 50.60, respectively.

The subtracter 90 calculates the steering force Fm applied to the steering wheel 20.
The amount of rotational displacement Xm of the steering shaft 21 rotated by the steering shaft 21 and the amount of steering displacement Y of the steering shaft 21 rotated by the steering shaft motor 22
The amount of twist occurring in the steering shaft 21 according to the difference between
-Y m, and the multiplier 91 is twisted l
This is an equivalent circuit that calculates a steering force proportional to fiXm-Ym and a steering reaction force applied from the steering shaft motor 22 to the steering shaft 21 as a reaction to the steering force, and the constant 1/Cm is the elastic coefficient of the steering shaft 21. . Subtractors 92 and 93 calculate each front wheel steering displacement @Ys of the left and right front wheel steering shafts 32 and 42 rotated by the steering force of the left and right front wheel steering shaft motors 30 and 40, respectively.
f1. Ys r 2 and the rotational displacement amounts X5fl and X5f2 of the left and right front wheel steering shafts 32, 42 according to the respective front wheel steering amounts of the left and right front wheels 33.43. The amount of twist Ys f 1−Xs
f1. This is an equivalent circuit representing Ys f 2 - Xs f 2, and the multiplier 94.95 is for each twist 1iYs f 1
-Xs f 1. As a reaction of the left and right front wheel steering force and the left and right front wheel steering force, which are each proportional to Ys f 2 - Xs f 2, the left and right front wheel steering shafts 32,
Each left and right front wheel steering reaction force Fsfl, Fsf applied to 42
2, where the constant 1/Ctf is the elastic coefficient of the left and right front wheel steering shafts 32.42.

The subtractors 96 and 97 are the left and right rear wheel steering shaft motors 50 and 6, respectively.
Left and right rear wheel steering shafts 52, 62 rotate with zero steering force.
The respective steering displacement amounts Ysrl and Ysr2, and the left and right rear wheels 53.
Left and right rear wheel steering shafts 52, 62 corresponding to each rear wheel steering of 63■
The amounts of torsion Y occurring in the left and right rear wheel steering shafts 52 and 62, respectively, in accordance with the winter wear of the respective rotational displacement amounts X5rl and X5r2.
These are equivalent circuits representing srl-Xsrl and Ysr2-Xsr2, respectively, and the multipliers 98.99 each represent the torsion amount Ysrl--
Xs r 1. As a reaction to the left and right rear wheel steering forces and the left and right rear wheel steering forces, which are each proportional to Ys r 2 - Xs r 2 , the left and right rear wheel steering shafts 52 .
Each left and right rear wheel steering reaction force Fsr1, Fsr applied to 62
2, where the constant 1/Ctr is the elastic coefficient of the left and right rear wheel steering shafts 52, 62.

In the control block configured as described above, the left and right front wheel steering reaction force Fsf of the first and second slave portions Bl and B2 is
l and Fsf2 are each expressed as in the following equations.

Fs f 1 = (Ys f 1 - Xs f 1) /
Ct f... (Formula 1) % Formula %... (Formula 2) On the other hand, the composite front wheel steering reaction force Fsf of the left and right front wheel steering reaction forces Fsfl and Fsf2 is: Fsf=Fsfl+Fsf2... (Formula 3) The combined steering amount of the left and right front wheels is 33.43.
Since it is the average of each steering amount of 3.43, the composite front wheel rotational displacement l of the left and right front wheel steering axes 32°42 according to the same composite steering amount
X S f is expressed as X5f = (Xsfl + Each left and right front wheel steering displacement of the rudder shafts 32 and 42 iYs f
1. Ys f 2 has the same value, so Ysfl=Ys
f2=Ysf... It is expressed as (Formula 5). Note that this value Ysf is defined as a composite front wheel turning displacement amount Ysf. From the above (Formula 1) to (Formula 5), the composite front wheel steering reaction force F
s f, the composite front wheel rotational displacement amount Xsf, and the composite front wheel steering displacement 17Ysf, the composite front wheel elastic coefficient Csf is
r=Ctf/2... (Formula 6) If defined, Fsf= (Ysf-Xsf)/Csf... (Formula 7
) Also, the third and fourth slave sections B3. Regarding B4,
Similarly to the first and second slave units Bl and B2, the following equation holds true.

Fs r 1 = (Ys r 1 - Xs r 1) /
Ctr... (28) Fsr2= (Ysf2-Xsf2)/Ctr...
(Formula 9) Fsr=Fsrl+Fsr2・+ + (Formula 10)x
sr=(xsrl+X5r2)/2... (Formula Ysr
l = Ysr2 = Ysr - (Formula 12) Note that the value Fsr
is the composite rear wheel steering reaction force, the value Xsr is the composite rear wheel rotational displacement amount, and the value Ysr is the composite rear wheel steering displacement amount. Then, if the composite rear wheel elastic coefficient Csr is defined as C3r=Ctr/2... (Equation 13),
The relationship between the composite rear wheel steering reaction force Fsr, the composite rear wheel rotational displacement amount Xsr, and the composite rear wheel steering displacement amount Ysr is Fs r = (Ys r - Xs r) /C
s r... (Formula 14) Using these relationships of (Formula 7) and (Formula 14), the third
If the control block diagram in the figure is simplified, it becomes as shown in FIG. 4, where the block 22a1 is a multiplier 70a.

71a, 72a, 85a, 87a, 91, subtractor 77a
, 90 and the adder 83a are the same as those given the same reference numerals in FIG. Block 30b, multiplier 73b and subtractor 78b correspond to blocks 30a, 40a, multipliers 73a, 74a and subtractors 78a, 79a in FIG.
b and the multiplier 94b are the third
Adder 84a, subtracter 92, 93, and multiplier 94.
95 equivalent circuit is shown. In addition, block 50b,
The multiplier 75b and the subtracter 80b are each block C17 in FIG.
multipliers 75a, 76a and subtractor 8
0a and 81a, and the subtracter 96b and multiplier 98b are the adder 86a, subtracter 96, 97, and multiplier 98 in FIG. 3 based on the relationship of (Equation 14). .99 equivalent circuit is shown.

In the control block of FIG. 4 configured as described above, considering the balance (steady state) of the system, the following equation holds true.

Kmf-Fm-Ks f f-Fs f+Ks rr-
Fsr-= (Formula 15) % formula % (Formula 16) Kmpr-Ym=Kspr-Ysr-.- (Formula 17) In addition, the steering shaft 21. Left and right front wheel steering shafts 32.42° Steering forces applied to left and right rear wheel steering shafts 52 and 62, respectively (iffi
Rudder reaction force) Fm, composite front wheel steering force (composite front wheel steering reaction force) F
sf (-Fsfl+Fsf2), composite rear wheel steering force (
Synthetic rear wheel steering reaction force) Fsr (=Fsrl+Fsr2) and each of the above-mentioned axes 21, 32 . (42), 52 (62)
Each twist occurring in ii X m −Ym, Ys f
-Xs r and Ys r - Xs r are expressed as follows using the elastic coefficients 1/Cm, 1/Cs f, and 1/Cs r.

Fm-(1/Cm) (Xm-Ym) (Formula 18) % formula % f) (Formula 19) F s r= (1/Cs r) - (Ys r-X
sr)... (Formula 20) Here, the left and right front wheels 33.43 and the left and right rear wheels 53.63 are not in contact with the road surface, that is, the left and right front wheel steering reaction force and the left and right rear wheel steering reaction force are applied from the road surface. State of not receiving (Fsf=
0. Fsr=O), the first . Second
Slave part B1. B2 and 3rd. Fourth slave B3.
According to the ratio of the rotation angles respectively transmitted to B4, that is, the respective composite steering amounts of the left and right front wheels 33.43 and the left and right rear wheels 53.63 to the rotational displacement amount Xm of the steering shaft 21 according to the co-movement amount of the steering handle 2o. The respective composite rotational displacement amounts Xsf, Xs of the left and right front wheel steering shafts 32, 42 and the left and right rear wheel steering shafts 52, 62
If the ratio of r is defined as a front wheel steering gear ratio αf and a rear wheel steering gear ratio αr, these gear ratios αf and αr are expressed by the following equations from (Equations 15) to (Equations 20).

ex f =X s f /Xm=Kmp f /K
s p f... (Formula 21) % formula %... (Formula 22) As shown in the above (Formula 22), the rear wheel steering gear ratio αr is determined by the coefficient Kmp r being positive (or negative). When , it becomes positive (or negative). And these gear ratios α'
, αr can be changed by changing the value of the steering wheel 20.
For the same amount of movement, the left and right front wheels are 33.43, and the left and right rear wheels are 5.
In the embodiment described later, these gear ratios αf and αr represent steering characteristics and are treated as parameters that change depending on the vehicle speed.

In addition, the left and right front wheels 33.43 are fixed (Xsf=0) and the left and right rear wheels 53.63 are not in contact with the road surface (Fsr
=Q) state, the first. Second slave part Bl, B2
If the ratio of the force transmitted from the front wheel to the mask part A, that is, the ratio of the steering reaction force Fm to the composite front wheel steering reaction force Fsf, is defined as the front wheel force reverse transmission ratio βf, this force reverse transmission ratio βf is expressed as (Equation 15
), it is expressed by the following formula.

βf=Fm/Fs f=Ks f f/Kmf ---
(Equation 23) Changing this force reversal ratio βr means changing the steering reaction force Fm with respect to the same composite front wheel steering reaction force Fsf. The feed ratio βf is treated as a parameter that indicates steering characteristics and changes depending on the vehicle speed.

In addition, the left and right front wheels 33.43 were not in contact with the road surface (F
sf=Q) and the left and right rear wheels 53.63 were fixed (Xs
r=Q) state, the third. Fourth slave B3. B4
If the ratio of the force transmitted from the rear wheel to the mask part A, that is, the ratio of the steering reaction force Fm to the composite rear wheel steering reaction force Fsr, is defined as the rear wheel force reverse transmission ratio βr, this force reverse transmission ratio βr is expressed as (Equation 15
), it is expressed by the following formula.

βr=Fm/Fs r=Ks f r/Kmf
- - (Formula 24) Note that as shown in the above (Formula 24), this force reversal ratio βr becomes positive (or negative) when the coefficient K s f r is positive (or negative). Changing this force reversal ratio βr means changing the steering reaction force Fm with respect to the same composite rear wheel steering reaction force Fsr. In the embodiment described later, this force reversal ratio βr It is treated as a parameter that indicates characteristics and changes depending on vehicle speed.

Furthermore, the ratio between the steering reaction force Fm and the rotational displacement ffl If the coefficient Qsf is the coefficient, and the ratio between the composite rear wheel steering reaction force (rear wheel steering force) Fsr and the composite rear wheel rotational displacement amount Xsr is the rear wheel steering elastic coefficient Qsr, then the following formula holds: Qm=Fm/Xm ... (Formula 25) Qsf=F
sf/Xsf -- (Formula 26) QSr=FSr/XSr
(Formula 27) Note that the front wheel steering elastic coefficient Qsf is a constant determined by the friction between the left and right front wheels 33°43 tires and the road surface, and the rear wheel steering elastic coefficient Qsr is the left and right rear wheel steering elastic coefficient Qsf. 53.63 is a constant determined by the friction between the tires and the road surface. On the other hand, the rotational displacement ffl

Based on (Formula 21), (Formula 23), and (Formula 24), Xm=
X s f /a f + (Cm-βf+Csf/α
f) HF s f +Cm-βr-Fsr...
(Equation 28), and the rotational displacement amount Xm is expressed as (Equation 15)
, (Formula 17), (Formula 18), (Formula 20).

Based on (Formula 22), (Formula 23), and (Formula 24), Xm=
X5 r/αr+ (Cm・βr+C3r/αr)
・F s r +Cm-βf-Fsf... (Formula 29
) is also expressed as. Here, let the front wheel elastic coefficient Qsf be the value Q 3 f oo when the left and right front wheels 33.43 are fixed (Xsf=O) and the left and right rear wheels 53.63 are not in contact with the road surface (Fsr=O). For example, the value Qsfo
From (Formula 15), (Formula 23), and (Formula 28), o is Qs foo=αf-βf/(otf・βf-Cm+C
s f +otf ・βr−Cm−FSr/FSf)・
... It is expressed as (Formula 30). In addition, the left and right front wheels 33.43 are not in contact with the road surface (Fsf=O) and the left and right rear wheels 53.63
If the rear wheel elastic modulus Qsr in a state where is fixed (Xsr=O) is the value Qs roo, the value Qs roo is
From (Formula 15), (Formula 24), and (Formula 29), Qs roo=otr ・βr/(αr・βr−Cm+
Csr+txr-βf-Cm-Fsf/Fsr)... It is expressed as (Formula 31). Then, when the steering elastic coefficient Qm is expressed using the front wheel elastic coefficient Qsf and the rear wheel elastic coefficient Qsr, the steering elastic coefficient Q
m is the above (Formula 15), (Formula 23), (Formula 24), (Formula 2
6) to (Equation 31). Here, the value Qsfoo is the left and right front wheel 3.
Considering that 3.43 is the front wheel elastic modulus in a fixed state, the value Qsfoo is extremely thick compared to the front wheel elastic modulus Qsf in normal conditions (Qsfoo>>Qs
f), and the value Q 3 roo is 53.63 for the left and right rear wheels.
Considering that is the rear wheel elastic coefficient in a fixed state, the value Qs roo is the rear wheel elastic coefficient Qsr under normal conditions.
extremely large compared to (Qs roo >> Qs r)
Therefore, the above (Equation 32) is transformed as shown in the following equation.

Qm=αf-'βf-Qsf+ctr-βr-Qsr・
(Formula 33) Then, changing these products αr and βf and αr and βr, respectively, is necessary for the steering elastic coefficient Qm, that is, for the same rotational displacement ilXm of the steering shaft 21. This means a change in the steering force Fm, and in the embodiment described later, the products αf and βf and the products αr and βr each represent a steering characteristic and are treated as parameters that change depending on the vehicle speed.

According to the above (Equations 21) to (Equations 24), the coefficient Kmpf,
Calculating Kmpr, Ksff, Ksfr・Coefficient Kmp
f, Kmp r, Ks f f, and Ks fr are as shown in the following equations.

Kmpr-cxf-Kspf ・--(Formula 34) Kmp
r=txr−Kspr---(Formula 35) Ksff−βf
-Kmf・=C formula 36) Ksfr=βr−Kmf...
(Formula 37) Here, coefficients Kspf, Kspr, Kmf
, Kmr are coefficients Kmpf, Kmpr, Ksf f, respectively.
Since it is a relative value to Ksfr, it is defined as a constant in the embodiment described later, and the coefficient Kmpf.

Kmpr, Ksff, and Ksfr are the front wheel steering gear ratio αf and the rear wheel steering gear ratio αr, respectively.

It is treated as a value that changes depending on the front wheel force reverse transmission ratio βr and the rear wheel force reverse transmission ratio βr.

C5 specific example As mentioned above, the front wheel steering gear ratio αf.

Based on the rear wheel steering gear ratio αr, the front wheel force reverse transmission ratio βf, and the rear wheel force reverse transmission ratio βr, the coefficient Kmpr.

A specific embodiment of the present invention will be described with reference to the drawings, in which Kmpr, Ks f f, and Ks f r are calculated by a microcomputer to control the steering of the left and right front wheels 33.43 and the left and right rear wheels 53.63, respectively. FIG. 5 shows a mask part A operated by the driver, a first slave part B1 and a second slave part B2 that steer the left and right front wheels 33.43, respectively, and a third slave part B1 and a second slave part B2 that steer the left and right rear wheels 53.63, respectively. A vehicle power steering system is shown that includes a slave section B3, a fourth slave section B4, and an electric control device C that electrically controls the first to fourth slave sections 81 to B4 of the mask section A1. The mask unit A and the first to fourth slave units 81 to B4 have substantially the same basic configuration as that shown in FIG. 2, so the same parts are given the same reference numerals and will not be described in detail.

Mask part A is the steering handle 20. Steering shaft 21° Steering shaft motor 22. Steering displacement sensor 23 and steering force sensor 24
It is equipped with The steering displacement sensor 23 includes a slider 23b that slides on a grounded resistor 23a at a midpoint in accordance with the rotation of the steering shaft 21, and a voltage source 23c connected to both ends of the resistor 23a. , a positive (or negative) voltage signal representing a steering displacement amount Ym proportional to the rotation angle of the steering shaft 21 with respect to the reference position is output by left (or right) rotation of the slider 23b. The steering force sensor 24 is a strain gauge 24 that is attached to the steering shaft 21 and whose resistance value changes depending on the amount of twist of the coaxial shaft 21.
a, and a fixed resistor 24 with this strain gauge 24a as one side.
b, 24c, and 24d, and a strain gauge 24a.

It consists of a voltage source 24e connected between the connection point of the resistor 24b and the connection points of the resistors 24C and 24d. The steering force sensor 24 detects a positive (or negative) steering force Fm proportional to the amount of twist generated in the steering shaft 21 in response to left (or right) rotation of the steering wheel 2o from the connection point between the strain gauge 24a and the resistor 24d.
outputs a voltage signal. Note that the resistors 24b and 24c
The connection point of is grounded.

The first slave part Bl is a left front wheel steered shaft motor 30° pinion 31. Left front wheel steering shaft 32. Left front wheel 33, rank axis 34
, a quirod 35, a knuckle arm 36, a front left wheel steering displacement sensor 37, and a front left wheel steering reaction force sensor 38. The left front wheel steering displacement amount sensor 37 is connected to the left front wheel steering shaft 3.
2, and a voltage source 37c connected to both ends of the resistor 37a. ) rotation, that is, by steering the left front wheel 33 to the left (or right), the left front wheel steering displacement 1Ysf is proportional to the rotation angle of the left front wheel steering shaft 32.
Outputs a positive (or negative) voltage signal representing l. The left front wheel steering reaction force sensor 38 is a strain gauge 3 attached to the left front wheel steering shaft 32 and whose resistance value changes according to the amount of twist of the same shaft 32.
8a and a fixed resistor 3 with this strain gauge 38a as one side.
8b.

The bridge circuit formed by 38c and 38d, the connection point between the strain gauge 38a1 and the resistor 38b, and the resistors 33c and 38d
The voltage source 38e is connected between the connection points of the voltage source 38e. The left front wheel steering reaction force sensor 38 detects a left front wheel steering reaction force F proportional to the amount of twist generated in the front wheel steering shaft 32 in response to left (or right) steering of the left front wheel 33 from the connection point between the strain gauge 38a and the resistor 38d.
A positive (or negative) voltage signal representing sfl is output.

Note that the connection point between the resistors 38b and 38C is grounded.

The second slave section B2 is configured similarly to the first slave section B1, and has a right front wheel steering shaft motor 40. Binion 41. Right front wheel steering shaft 42. Right front wheel 43, steering shaft 44, tie rod 45, knuckle arm 46° Right front wheel steering displacement sensor 4
7 and a right front wheel steering reaction force sensor 48. The front right wheel steering displacement amount sensor 47 includes a resistor 47a and a slider 47b.
The front left wheel steering displacement amount sensor 37 is configured similarly to the left front wheel steering displacement amount sensor 37 by using the voltage source 47C and the left (or right) steering of the right front wheel 43. (or negative) voltage signal. The front right wheel steering reaction force sensor 48 is configured in the same manner as the front left wheel steering reaction force sensor 38, and includes a strain gauge 48a, fixed resistors 48b, 48c, 48d, and a voltage source 48e, and is configured in the same way as the front left wheel steering reaction force sensor 38. Accordingly, a positive (or negative) voltage signal representing a front right wheel steering reaction force Fsf2 proportional to the amount of twist generated in the front right wheel steering shaft 42 is output.

The third slave section B3 and the fourth slave section B4 are also connected to the first slave section B3 and the fourth slave section B4.
It is configured in the same manner as the slave part B1, and includes left and right rear wheel steering shaft motors 50, 60, binions 51°61, left and right rear wheel steering shafts 52, 62, left and right rear wheels 53°63, and rank shafts 54, 6.
4. Tie mouth/throat 55, 65, knuckle arm 56.6
6. Left and right rear wheel steering displacement amount sensors 57, 67 and left and right rear wheel steering reaction force sensors 58, 68 are provided. The left and right rear wheel turning displacement amount sensors 57, 67 have resistors 57a, 67a, respectively.
, the slider 57b, 67b and the voltage sources 57c, 67c are configured in the same manner as the left front wheel steering displacement amount sensor 37, and the left and right rear wheel steering shaft 52 is configured by each (or right) steering of the left and right rear wheels 53, 63. , 62, positive (or negative) representing the left and right rear wheel steering displacement amounts Ys f l, Ys r 2 proportional to each rotation angle.
output voltage signals respectively.

The left and right rear wheel steering reaction force sensors 58 and 68 include strain gauges 58a and 613a, and fixed resistors 58b and 58c, respectively.

58d, 68b, 68c, 68d and voltage sources 58e, 6
8e is configured in the same manner as the left front wheel steering reaction force sensor 38, and each sensor is proportional to the amount of torsion generated in the left and right rear wheel steering shafts 52.62 in response to individual (or right) steering of the left and right rear wheels 53.63. Positive (or negative) voltage signals representing left and right rear wheel steering reaction forces Fsrl and Fsr2 are output, respectively.

The electric control device C receives the steering displacement Hym from the steering displacement amount sensor 23, the tfi rudder force sensor 2 squid sensor steering force (or steering reaction force) Fm, and each left and right front wheel turning displacement fiYsf1 from the left and right front wheel turning displacement amount sensors 37 and 47. , Ysf2. Each left and right front wheel steering reaction force (or left and right front wheel steering force) Fsfl, Fsf2 from the left and right front wheel steering reaction force sensor 38, 48, each left and right rear wheel steering displacement QYsr from the left and right rear wheel steering displacement amount sensor 57, 67 1 + Y S r 2 , each left and right rear wheel steering reaction force (or rear wheel steering force) Fsrl, Fsr2 from the left and right rear wheel steering reaction force sensor 58°68, and the rotation of the output shaft of the transmission are big-amplified, By inputting the vehicle speed ■ from the vehicle speed sensor 100 that generates a pink-up signal corresponding to the vehicle speed, the rotation control amount Mm of the steering shaft motor 22, each rotation control amount Msfl, Msf2, and Each rotation control amount Ms of left and right rear wheel steering shaft motor 50.60
Microcomputer 101 that calculates rl and Msr2
It is equipped with

The microcomputer 101 controls each of the above-mentioned sensors 23.2.
4, 37.3B, 47.48.57.58.67.68
, 100, a read-only memory (hereinafter simply referred to as ROM) 101b that stores a program corresponding to the flowchart shown in FIG. 7 and constants necessary for executing the program, and a program A central processing unit (hereinafter simply referred to as CPU) 101C that executes the program, a writable memory (hereinafter simply referred to as RAM) 101d that temporarily stores variables necessary for program execution, and a steering shaft motor calculated by executing the program. 22 rotation control amount Mm, each rotation control amount Msfl, Msf2 of the left and right front wheel steered shaft motors 30, 40, and each rotation control amount 11M5 of the left and right rear wheel steered shaft motors 50 and 60.
r1. Output port 101e that outputs Ms r 2
and these input ports 101a, ROM101
b. CPU101c.

It includes a lotus 101f that commonly connects the RAM 101d and the output port 101e. Human powered boat 101a
, each sensor 23, 24 . 37°38.47.48
．． An analog-to-digital converter (hereinafter simply referred to as A/
D converter) 103 is connected, and multiplexer 1
02 converts analog signals from each sensor 23, 24, 37, 38, 47, 48°57.58, 67.68, 100 into a control signal supplied from CPU 01c via input capo-1-1018. Accordingly, A, /
The output signal is selectively outputted to the D converter 103, and the A/D converter 103 converts this output signal into a digital signal in synchronization with this control signal and supplies it to the input capo-1-101a. Multiplexer 102 and each sensor 23, 24, 37, 38,
Buffer amplifiers 104 a, 104 b, 104 are provided between 47.48.57° and 58.67.68, respectively.
c, 104 d, 104e, 104f,
104g, 104h, 104i.

104j is connected. Furthermore, buffer amplifier 1
A low pass filter (LPF) is installed between each of 04d, 104f, 104h, 104j and the multiplexer 102.
105a, 105b, 105c.

105d is connected. These low-pass filters 105a, 105b, 105c, and 105d are, for example,
Operational amplifier ○P as shown in Figure 6.

Capacitors C, C1, and resistors R1, R2, R3゜R4
Each is composed of a known active filter consisting of
This filter 105a (105b, 105c,
The voltage transfer function of 105 d) is expressed by the following (Equation 38) to (Equation 41), and its cutoff frequency is set to about 1 to 10 Hertz.

V2/V1=G-bo/ (S” +b 1・S+b
o) ... (Formula 38)%Formula% (Formula 39) bl= (1-G)/(R2・CI)+1/(
R1・C) +1/ (R2・C)... (
Equation 40) G=1+R4/R3... (Equation 41) This removes the high frequency components contained in the turning reaction force detection signals output from each turning reaction force sensor 38, 48, 58°68. be done.

Further, between the multiplexer 102 and the vehicle speed sensor 100, there is a waveform shaping circuit 100a that shapes the piff knob signal from the vehicle speed sensor 100 into a rectangular wave signal, and a waveform shaping circuit 100a that inputs this rectangular wave signal and generates a voltage proportional to the frequency of the signal. A frequency/voltage converter (hereinafter simply referred to as f
/V converter) 100b, and f/V converter 100b.
A buffer amplifier 100c is connected to supply the output of the buffer amplifier 100c to the multiplexer 102. The output port 101e is connected to a digital-to-analog converter (hereinafter simply referred to as D/
The D/A converter 106a converts the rotation control amount Mm into an analog signal and controls the steering shaft motor 22 via the power amplifier 107a.

In addition, the same output boat 101e has respective rotation control amounts Msfl, Ms"2 of the left and right front wheel steered shaft motors 30 and 40, and each rotation control amount Msr of the left and right rear wheel steered shaft motors 50 and 60.
1. D/A converters IQ6b and 106c each convert Ms r 2 into digital to analog.

IQ6d and 106e are connected, and the D/A converter 106
b, 106c, 106d, 106e are each rotation control iMs
r1. Ms f 2 and each rotation control ff1M5rl
, Msr2 are converted into analog signals and power amplifiers 107b, 107c, 107d, 1
07e, the left and right front wheel steering shaft motors 30, 40 and the left and right rear wheel steering shaft motors 50, 60 are controlled, respectively.

The operation of the vehicle power steering system configured as described above will be explained using the flowchart shown in FIG. When the ignition switch is turned on, the CPU 101c starts executing the program from step 200, and in step 201, the steering displacement amount sensor 23 detects the steering displacement ffi.
Ym, Fffi Steering force (or steering reaction force) Fm from the rudder force sensor 24, each left and right front wheel turning displacement amount Ys f 1. Ys f 2, left and right front wheel steering reaction force obtained by processing each left and right front wheel steering reaction force (or front wheel steering force) Fsfl, Fsf2 from the left and right front wheel steering reaction force sensor 38.48 using low-pass filters 105a and 105b. (or front wheel steering force) Fsfl*, Fsf2*, left and right rear wheel steering displacement amount sensors 57, 67, left and right rear wheel steering displacements QYs r l, Ys r 2, and left and right rear wheel steering reaction force sensors 58, 68 The respective left and right rear wheel steering reaction forces (or rear wheel steering forces) Fsrl and Fsr2 are filtered through a low-pass filter 1.
Input the left and right front wheel steering reaction force (or front wheel steering force) Fsrl* and Fsr2* processed by 05c and 105d to RA.
In step 202, the vehicle speed ■ is inputted from the vehicle speed sensor 100 and stored in the RAM 101d, and the program proceeds to step 203.

At step 203, the CPU 10IC RAs the vehicle speed ■.
Read from M101d and based on this vehicle speed
The front wheel steering gear ratio αf, the rear wheel steering gear ratio αr, the product αf/βf of the above ratio αr and the front wheel force reverse transmission ratio βf, and the product αf and the rear wheel force reverse transmission ratio βf of the above ratio αr and the rear wheel force reverse transmission ratio αf shown in the characteristic diagrams of FIGS. The product αr・βr with the feed ratio βr is ROMI Ol b
Each value α[, αr is obtained by reading each value from the parameter table provided in the internal parameter table, and each value αf·βf, αr·βr is divided by each value αf, αr to obtain each value βf.

Calculate βr. The characteristic diagram in Fig. 8A shows the change in the value of the front wheel steering ratio 4/ratio αf with respect to the vehicle speed ■.
Mr. α' remains a nearly constant value even if the vehicle speed ■ changes. The characteristic diagram in Figure 8B shows the change in the value of the rear wheel steering gear αr with respect to the vehicle speed ■. It changes continuously from negative to positive as it increases from
Moreover, the maximum absolute value of αr is approximately 1/3 of the value of the front wheel steering gear ratio αr. As a result, in the low vehicle speed range, the left and right rear wheels 53.63 are steered in the opposite phase to the left and right front wheels 33°43, and in the high vehicle speed range, the left and right rear wheels 53.6
3 is steered in the same phase with respect to the left and right front wheels 33.43. Note that the amount of steering of the left and right rear wheels 53, 63 is approximately 1/3 of the amount of steering of the left and right front wheels 33, 43. The characteristic diagrams in FIGS. 8C and 8D show the product αf/βf of the front wheel steering ratio αf and the front wheel force reversal ratio βr with respect to the vehicle speed V, and the rear wheel steering ratio α
It shows the change in each value of the product α'・βr of r and the front wheel force reverse transmission ratio βr.These products αf・βf and products αr・βr are constant values when the vehicle speed ■ is small, and when the vehicle speed V This means that the steering force required to rotate the steering wheel 20 gradually increases as the vehicle speed increases.

In step 203 above, the front and rear wheel steering gear ratio αf
, αr and the front and rear wheel force reverse transmission ratios βf, βr, the program proceeds to step 204, and the CPU 01 C calculates the coefficient Kmpf in step 204.

Kmpr, Ksrf, Ksfr are the front and rear wheel steering gear ratios αf, αr and the front and rear wheel force reverse transmission ratios βf, βr.
and the coefficients Kspf, K stored in ROMI O1b
Based on spr and Kmf, (Formula 34) to (Formula 37)
Calculate by executing the calculation shown in . Next, in step 205, the CPUI OI c is the rotation control amount Mm of the steering shaft motor 22, and the rotation control amount Mm of the left and right front wheel steering shaft motors 30.
, 40 and each rotation control amount Msr 1°Msr2 of the left and right rear wheel steered shaft motors 50, 60 using the above calculation coefficients Kmp f, Kmp r,
Ksrf, Ksfr, the above coefficients Kspf, Kspr.

Kmf, steering displacement Ym, steering force (or steering reaction force)
Fm, left and right front wheel steering displacement amount Ysrl, Ysf2, left and right rear wheel steering displacement fiYs r l, Ys r 2, left and right front wheel steering reaction force (or steering force) Fsrl*, Fsf2*, and left and right rear wheel steering reaction force It is calculated by executing the calculations shown in the following (Formula 42) to (Formula 45) based on Fsrl*, I;'sr2*.

Mm=Kmf HFm−Ks f f −(Fs f
1*+Fsf2*)-Ksfr-(Fsrl*+Fsr
2*) HH+ (Formula 42) % formula % ... (Formula 43) Ms f 2 = Kmp f - Ym - Ks p f
-Ys f 2... (Formula 44) % formula %... (Formula 45) Msr2=Kmpr Ym-Kspr-Ysr 2.
... (Formula 46) After the calculation in step 205, the program executes step 206
, CPUl0IC determines the rotation control amount Mm of the steering shaft 21.
, each rotation control amount Msfl of the left and right front wheel steering I sleeves 32, 42
, Msf2 and the control signals representing the respective rotational control amounts Msrl and Msr2 of the left and right rear wheel steering shafts 52 and 62 are output to the boat 10.
D/A converters 106a, 106 respectively via 1e
b, 106 c.

It outputs to 106d, , 106e. D/A converter 106
a, 106b, 106c, 106d, 106e are power amplifiers 107a, 107b, 107c, 107d, respectively.
The rotations of the steering shaft motor 22, left and right front wheel steering shaft motors 30, 40, and left and right rear wheel steering shaft motors 50 and 60 are controlled via the motor 107e.

Operation in which the rotation of the steering shaft 21 is controlled, the left and right front wheel steering shaft 3
The operation in which the left and right front wheels 33.43 and the left and right rear wheels 53.63 are steered by controlling the respective rotations of the left and right rear wheel steering shafts 52 and 62 is the same as the operation described in the basic configuration.

After the calculation in step 206, the CPU 10IC returns to execute the calculation in step 201 and performs steps 201 to 206.
Execute the cyclic calculation to steer the steering shaft 21 and left and right front wheels! 11
132.42 and the left and right rear wheel steering shafts 52.62.

As can be understood from the above explanation of the operation, in the above embodiment, the left and right front wheels 33 are rotated according to the rotational operation of the steering handle 20 by the calculations in steps 201, 204 to 206.
．． 43 and the left and right rear wheels 53, 63 are independently steered, and the left and right front wheels steering reaction forces Fsfl* and Fsf2 are generated by steering each of the left and right front wheels 33, 43 and the left and right rear wheels 53, 63.
* and the left and right rear wheel steering reaction forces Fsrl* and Fsr2* are sent back to the steering wheel 20 as steering reaction forces, so the driver can steer the left and right front wheels 33.43 and the left and right rear wheels 53.63.
The vehicle can be driven while feeling the steering reaction force, the steering reaction force, and the restoring force of the steering wheel in response to each turning. Also, this steering reaction force is determined by the calculation in steps 202 and 203 to calculate the vehicle speed
Since the value increases as the value increases, the steering stability improves. Furthermore, the left and right rear wheel steering reaction forces Fsfl*, Fsf2*, Fsrl*, and Fsr2* read in step 201 are the left and right rear wheel steering reaction forces output from each steering reaction force sensor 38, 48.58°68. Force Fs f 1°Fsf2. Fsr.
Among the frequency components included in l, l''sr2, the frequency components included in the high frequency region are filtered through the low-pass filter 105a.
, 105b, 105c, and 105d, the left and right front and rear wheels 33,
Even if 43°53.63 receives a turning reaction force from the road surface that changes at such a speed that the driver, who is the cause of the generation of the above-mentioned component, cannot react, the turning reaction force is not transmitted to the steering wheel 20 and the driver is unable to drive. If a person makes a mistake in operating the handle 20, this will not happen. Since the left and right front and rear wheels 33, 43, 53, and 63 are steered in accordance with the operation of the steering wheel 20, the steering stability of the vehicle is improved.

d. Modification In the above embodiment, the left and right front and rear wheels 33 are
, 43, 53, 63, which changes at a speed that the driver cannot react to, is not transmitted back to the steering wheel 20.
48, 58, and 68 are removed by low-pass filters 105a, 105b, 105c, and 105d made up of analog circuits. After the signal is converted into a digital detection signal by the A/D converter 103, high frequency components included in the digital detection signal may be removed by a low-pass digital filter.

In this case, it is preferable to provide a low-pass digital filter between the A/D converter 103 and the input port 1o1a. Further, after each detection signal in digital format is input into the microcomputer 101, an operation having the same function as that of the digital filter described above may be applied to each of the input detection signals inside the microcomputer 101.

In addition, in the above embodiment, each steering shaft 32, 42, 52
．． 62 is rotationally driven by each steered shaft motor 30, 40, 50, 60.
As shown in the specification and drawings of the issue, the oil discharged from the hydraulic pump is supplied to the hydraulic cylinder via a servo valve that is switched and controlled by a linear actuator, and the oil is coupled to the piston by the supplied discharge oil. The steering shaft may be reciprocated in the axial direction, and the movement may drive the tie rod to steer the wheels.

In this case, the steering displacement amount sensor detects the axial displacement of the steering shaft and outputs the detection signal to the microcomputer,
The steering reaction force sensor detects tensile and compressive strain in the axial direction of the steering shaft and outputs the detection signal to the microcomputer via a low-pass filter. It is better to keep it under control.

Furthermore, in the above embodiment, this invention is applied to each wheel 3.
3.43, 53.63, steering shaft motor 30, 4.
A steering mechanism consisting of steering shafts 32, 42, 52, 62, etc. is provided, and each wheel 33, 43, 53, 63
This invention was applied to a vehicle in which each steering mechanism independently steered the wheels, but this invention
As shown in the specification and drawings of the issue, the left and right front wheels 3
3.43 is controlled by a common front wheel steering mechanism, or the left and right rear wheels 53.63 are controlled by a common rear wheel steering mechanism. Also,
This invention is disclosed in Japanese Patent Application No. 60-133483 and Japanese Patent Application No. 60-1983.
The present invention is also applied to a vehicle in which only the left and right front wheels 33, 43 are steered as shown in the specification and drawings of No. 152831.

In these cases as well, the amount of displacement of the steering shaft in each steering mechanism is detected as the amount of steering displacement, the detection signal is output to the microcomputer, and the amount of distortion of the steering shaft is calculated as the amount of steering displacement. The detection signal is output to the microcomputer via a low-pass filter, and the microcomputer controls each steering mechanism based on these detection signals to rotate each wheel (steering wheel). All you have to do is steer it.

Even in the above-mentioned modifications, effects equivalent to those of the above-mentioned embodiments can be achieved.

[Brief explanation of drawings]

FIG. 1 is a diagram corresponding to the configuration of the invention described in the claims, FIG. 2 is a diagram showing the basic configuration of the vehicle power steering device according to the present invention, and FIG. 3 is the same as shown in FIG. 2. A control block diagram showing the control state in the basic configuration, FIG. 4 is a control block diagram that is a simplified control block diagram of FIG. 3, and FIG. 5 is a schematic diagram of a power steering system for a vehicle showing a specific embodiment of the present invention. figure,
6 is a diagram showing an example of the low-pass filter of FIG. 5, FIG. 7 is a flowchart of a program executed by the microcomputer of FIG. 5, and FIGS. 8A to 8D are diagrams showing specific examples of the present invention. It is a figure showing the steering characteristic in an example. Explanation of symbols 20... Steering handle, 21... Steering shaft, 22...
・Steering shaft motor, 23...Steering displacement sensor, 24・
・・Steering force sensor, 30, 40, 50.60 ・・Steering shaft motor, 32.42, 52° 62 ・・Steering shaft, 33
,43,53.63...Wheel, 37.47,57.6
7... Steering displacement amount sensor, 38.48, 58.68.
... Steering reaction force sensor, lOO... Vehicle speed sensor, 101
...Microcomputer, 105a, 105b. 105c, 105d...Low pass filter.

Claims (1)

[Claims] In a vehicle steering device that steers steering wheels in response to rotation of a steering handle, a steering shaft coupled to the steering handle;
a steering shaft actuator for rotationally driving the steering shaft; a steering control means coupled to a steering wheel for steering the wheel; and a steering force for detecting a steering force applied to the steering shaft from a steering handle. a steering force sensor that outputs a steering force detection signal representing the steering force; and a steering force sensor that detects a turning reaction force applied to the steering control means from the steering wheel and outputs a turning reaction force detection signal representing the steering reaction force. a steering reaction force sensor that detects a rotation angle of the steering shaft from a reference position as a steering displacement amount and outputs a steering displacement amount detection signal representing the detected steering displacement amount, and the steering force a first control amount determining means for determining a first control amount that increases in accordance with an increase in the detected steering force based on a detection signal and rotates the steering shaft in the direction in which the steering force is applied; High frequency component removing means for removing frequency components in a high frequency region among frequency components included in the force detection signal, and based on the turning reaction force detection signal from which the high frequency components have been removed by the high frequency component removing means. a second control amount determining means for determining a second control amount that increases in accordance with an increase in the detected steering reaction force and rotates the steering shaft in a direction to return the steering shaft to the reference position; Second
a steering shaft rotation control signal output means for outputting a steering shaft rotation control signal that is a composite of control amounts to the steering shaft actuator to control rotation of the steering shaft; a target steering amount determining means for determining a target steering amount that increases in accordance with an increase in the steering wheel and steers the steering wheel in a direction corresponding to the steering direction of the steering wheel; and steering control signal output means for outputting a rudder control signal to the steering control means to control the steering control means so that the amount of turning of the steered wheels becomes the determined target turning amount. A vehicle power steering device characterized by: