JPH05105099A - Vehicle steering controller - Google Patents

Abstract

PURPOSE:To provide a vehicle steering controller which is able to improve the transient responsiveness in steering without being affected by the resolution of a handwheel steering sensor. CONSTITUTION:A target rear-wheel steering angle fed forward item thetarp is operated by a step 701, a basic target yaw rate WaB is operated by a step 702 from handwheel angle thetaf and car speed V, a compensation target yaw rate Wac is operated by a step 703 from the car speed V and compensation steering torque Tc, and the basic target yaw rate WaB and the compensation target yaw rate Wac are added together by a step 704, setting them down to a target yaw rate W*. At a step 705, a target rear-wheel steering angle yaw rate feedback item thetary is operated from a difference between the target yaw rate W* and an actual yaw rate Wa, and at a step 706, the target rear- wheel steering angle feed forward item 6 thetarp and the target rear-wheel steering angle yaw rate feedback item thetary are added together, setting them down to a target rear-wheel steering angle 9c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering control device for assisting steering of wheels in a vehicle based on the steering or running condition of a driver.

[0002]

2. Description of the Related Art Conventionally, as a steering control device of this type,
There is known a device that corrects a basic target rear wheel steering angle calculated from a steering wheel angle or a vehicle speed based on a differential value of the steering wheel angle in order to improve the transient response of steering.

[0003]

However, in the above-mentioned conventional device, the resolution of the differential value is greatly affected by the resolution of the steering wheel angle sensor, and in order to obtain the differential value of the steering wheel angle, it is usually necessary to wait for a predetermined time before Since the difference between the steering wheel angle and the current steering wheel angle has to be calculated,
There is a problem that a time delay occurs in the behavior of the vehicle, and the transient responsiveness of steering cannot be improved yet.

Therefore, the present invention has been made in view of the above problem, and provides a vehicle steering control device capable of improving the transient response of steering without being affected by the resolution of the steering wheel angle sensor. The purpose is to

[0005]

To achieve the above object, a vehicle steering control device of the present invention comprises a vehicle speed detecting means for detecting a vehicle speed, a steering angle detecting means for detecting a steering angle of a steering wheel, and A steering control device for a vehicle, comprising: a target wheel rudder angle calculation means for calculating a target wheel rudder angle according to a vehicle speed and a steering angle of the steering wheel; Torque detection means for detecting torque, torque correction means for correcting the steering torque detected by the torque detection means with a parameter according to the steering angle of the steering wheel and the vehicle speed, and corrected steering corrected by the torque correction means The gist of the present invention is to include a target wheel steering angle correction means for correcting the target wheel steering angle according to the torque.

[0006]

In the above structure, the steering torque detected by the torque detecting means is corrected by the parameter corresponding to the steering angle of the steering wheel and the vehicle speed, so that the torque generated by the force applied to the tire from the road surface is eliminated, and the driver Only the torque component that tries to rotate the steering wheel is calculated. Then, the target wheel steering angle is corrected according to the corrected steering torque.

As a result, it is not necessary to calculate the differential value of the steering wheel angle to correct the target wheel steering angle, and the transient response of steering can be improved. Further, since it is not necessary to obtain the differential value of the steering wheel angle, the target wheel steering angle is not affected by the resolution of the steering wheel steering angle signal.

[0008]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a schematic diagram showing the overall configuration of the embodiment. The DC servo motor 2 mounted in the rear wheel steering mechanism 1 receives electric command signals from the electric control device 3 and rotates in the forward and reverse directions, and through the reduction gear 4, a rack and pinion mechanism with hydraulic power assist, that is, The steering mechanism 1 is connected to an input shaft (a torsion bar (not shown)).
A pinion gear 5 is attached to the other end of the torsion bar and meshes with a rack 7 formed at one end of a power piston 6. That is, one end of the torsion bar is rotated by the motor 2, the torsion bar is twisted, the throttle area of the hydraulic valve 8 is changed, and a hydraulic pressure is supplied in a direction to correct the torsion of the torsion bar to move the power piston 6. ing. Both ends of the power piston 6 are connected to a knuckle arm 10 via tie rods 9, respectively. The rear wheel 11 is supported by the knuckle arm 10 so as to be swingable in the left-right direction.

Therefore, the rear wheel 11 is steered left and right by the movement of the power piston 6 in the direction of arrow A in the figure. When the torsion bar is no longer twisted, the hydraulic valve 8
The throttle area becomes 0, the hydraulic pressure for moving the power piston 6 becomes 0, and the power piston 6 stops. Here, the rear wheel steering angle sensor 12 detects the position of the power piston 6 and outputs a signal. Based on this signal, the electric control device 3 obtains the rear wheel steering angle from the relationship between the position of the power piston 6 and the rear wheel steering angle, and also obtains the steering angular velocity from the change rate of the rear wheel steering angle. A positioning servo system that controls the positioning of the rear wheels 11 is configured so that the steering angle including the servo motor 2 and the steering angle of the rear wheels match. In addition, 13 is a power piston 6 through a hydraulic valve 8.
Reference numeral 14 denotes an oil tank for supplying oil pressure to the oil tank.

The front wheel steering angle sensor 15 detects the rotation of the steering wheel 26 and outputs a front wheel steering angle signal corresponding to the steering angle (handle angle) θf of the front wheels 16 to the control device 3. The vehicle speed sensor 17 detects the rotation speed of the axle or the wheel and outputs a vehicle speed signal corresponding to the vehicle speed V to the control device 3. The yaw rate sensor 18 is composed of a gyro or the like, and outputs a yaw rate signal according to a rotational angular velocity (yaw rate Wa) about the center of gravity of the vehicle to the control device 3.

Further, the front wheel steering torque sensor 25 detects a torque for steering the steering wheel. Hereinafter, the torque sensor 25 will be described. FIG. 2 shows the torque sensor 25.
FIG. 4 is a view as seen from the occupant side, with the above-mentioned assembled into the handle portion, and is a cross-sectional view of the main parts of FIG. 3. Reference numeral 26 is a handle, 103 is a handle side holding portion fixed to the handle 1 with a bolt or the like not shown, 105 is a mounting nut for fixing the steering torque detecting device of this embodiment to the handle 26, and 107 is described in detail later. It is an elastic body. In FIG. 3, the elastic body 107 is provided completely on the handle side holding portion 103 and the steering shaft side holding portion 109. Reference numeral 111 denotes a steering shaft, which transmits power to wheels via a drive shaft (not shown). 113 is a steering shaft 1
11 is a spline provided for fixing to the steering shaft side holding portion. FIG. 4 is a schematic diagram for explaining the torque detection unit. In FIG. 4, reference numeral 115 is a handle side rotating member fixed to the handle side holding portion 103, and reference numeral 117 is a steering shaft side rotating member fixed to the steering shaft side holding portion 109. Both the handle-side turning member 115 and the steering-shaft-side turning member 117 are cup-shaped drums made of a magnetic material, and rectangular sawtooth teeth 115A and 117A are formed at equal intervals in a portion facing each other. There is. The rectangular saw teeth 115A and 117
A is provided with a predetermined interval. Reference numeral 119 denotes a core, the coil 121 is wound around the core 119, and both ends thereof are connected to the power supply 123. An output circuit 125 is connected to the core 119 and outputs a change in magnetic flux as a change in voltage. It should be noted that the change in the magnetic flux is caused by the square saw tooth 115A of the steering side turning member and the steering shaft side turning member 117.
It is caused by the relative rotation of the tooth 117A having a square saw tooth shape. In this way, the detection means is the handle side turning member 1
15 and its square saw tooth 115A, the steering shaft side rotation member 117 and its square saw tooth 117A, core 1
19, coil 121, power supply 123, and output circuit 12
It is composed of 5.

Next, a detailed description of essential parts will be given with reference to FIGS.
This will be described using 1. FIG. 5 is a plan view of a portion other than the detecting portion as seen from the direction of the handle side holding portion 103.
5 is a sectional view taken along line AA in FIG. 5, and FIG. 7 is a steering shaft side holding portion 109.
FIG. 8 is a bottom view seen from above, and FIG. 8 is a sectional view taken along line BB of FIG. 5. The elastic body 107 has a U-shape as shown in FIGS. 10 and 11, and the key portions 107A at both ends are fitted and fixed in the grooves 137 of the upper fixing plate 135 and the lower fixing plate 133. Here, R-shaped taper surfaces 139 as shown in FIG. 9 are provided at the four corners of the groove 137. The lower fixing plate 133 and the upper fixing plate 135 have outer peripheral protrusions 133A and 135A as shown in FIG. 8, which suppress the radial movement of the elastic body 107. The steering shaft side holding portion 109 has a shape in which the cylindrical portion 109A is specifically formed in a donut-shaped ring, and the hexagon bolt 129 and the nut 143 are provided in the lower ring portion.
Is fixed to the lower fixing plate 133 by the elastic body 1
The key portion 107A of 07 is fixed with scissors. Similarly, the handle side holding portion 103 includes the hexagon bolt 127 and the nut 1.
It is fixed to the upper fixing plate 135 by 41 and is fixed by sandwiching the key portion 107A of the elastic body 107. The tip of the cylindrical portion 109A of the steering shaft side holding portion 109 is the upper fixed plate 1
A predetermined gap is provided between the central portion of the handle 35 and the central portion of the handle side holding portion 103 so as not to come into contact with each other. Further, the upper fixing plate 135 is also the cylindrical portion 109A of the steering shaft side holding portion 109.
A predetermined interval is provided so as not to come into contact with. The upper disc 131 is fixed to the cylindrical portion 109A of the steering shaft side holding portion 109 by a pin x. Also, this upper disc 131
As shown in FIG. 5, the stopper 131a is provided with a diameter larger than the outer shape of the hexagon bolt 127 by a predetermined amount. Screw hole 1 provided in the handle side holding portion 103
03A is a screw hole for fixing the handle side holding portion 103 to the handle with a bolt or the like not shown. In FIG. 6, the handle side turning member 115 and the steering shaft side turning member 117 described in FIG. 4 are respectively screwed by screws 145 and 147 to the handle side holding portion 103 and the steering shaft side holding portion 10.
It is fixed at 9. The elastic body 107 is the lower fixing plate 133.
When fixing with the groove 137 of the upper fixing plate 135, when considering one elastic body 107, the position of the groove 137 of the upper fixing plate 135 corresponding to the groove 137 of the lower fixing plate 133 is 1 It is staggered. Therefore, the hexagon bolt 1
When the screws 27 and 129 and the nuts 141 and 143 are screwed and fixed, the elastic body 107 is displaced by one degree deviation of the corresponding grooves 137 of the lower fixing plate 133 and the upper fixing plate 135.
The initial strain can be given to the elastic member 107, the play concerning the holding between the elastic body 107 and the lower fixing plate 103 and the upper fixing plate 135 can be eliminated, and the restoring force to the origin when there is no load is increased. This makes it possible to perform zero point adjustment.

Next, in this embodiment having the above-mentioned structure,
The operation will be described. In FIG. 6, the steering shaft side rotating member 117 and the lower fixed plate 1 rotate integrally with the steering shaft.
33 and the upper disc 131. On the other hand, what rotates integrally with the handle is the handle-side holding portion 103, the upper fixing plate 135, and the handle-side rotating member 115.
The elastic body 10 is provided between the handle side and the drive shaft side.
When the steering wheel is turned through 7, twisting occurs. As a result of this twist, the handle side turning member 11
5, relative rotation occurs between the steering shaft side turning member 117 and the steering wheel side turning member's square saw tooth 115A and the steering shaft side turning member's square saw tooth 117A. The position changes and the resulting change in magnetic flux is
19, coil 121, power supply 123, and output circuit 12
Detect at 5.

When torque is generated because the handle is turned and the elastic body 107 is twisted, the taper surface 139 as shown in FIG. 9 is provided. Therefore, when the torque is small (the elastic body 107). If the twist of is small),
The elastic body 107 is easily bent, and when the torque is large (when the elastic body 107 is largely twisted), the area in contact with the tapered surface 139 of the elastic body 107 is large, and thus the elastic body 107 is less likely to be twisted. This means that if the torque generated when the steering wheel is turned is small, twisting is likely to occur, and if the torque is large, twisting is less likely to occur, and since the torque and the amount of twisting are not directly proportional, If is small, weak detection is performed,
When the torque is large, it is possible to satisfy the characteristic required for the steering torque sensor, which does not require weak detection (it need not be so sensitive).

As a result, a voltage signal proportional to the steering torque is obtained. The control device 3 will be described with reference to FIG. 12. The control device 3 includes a microcomputer (hereinafter, referred to as a microcomputer) 19 including waveform shaping circuits 20, 21, an analog buffer 22, an A / D converter 23, and a drive circuit 24. ing. The waveform shaping circuit 20 is a vehicle speed sensor 17
The vehicle speed signal from is waveform-shaped and is taken into the microcomputer 19, and the waveform shaping circuit 21 waveform-shapes the signal from the front wheel steering angle sensor 15 and is taken into the microcomputer 19. The analog buffer 22 takes in each signal from the rear wheel steering angle sensor 12 and the yaw rate sensor 18 steering torque sensor 25, and the A / D converter 23 performs analog-digital conversion. The drive circuit 24 supplies a current corresponding to the current command value signal If from the microcomputer 19 to the DC servo motor 2.

Next, the operation of the control device 3 thus constructed will be described with reference to FIGS. FIG.
14 shows the main processing routine of the microcomputer 19, and FIG.
The vehicle speed pulse processing based on the pulse signal from the vehicle speed sensor 17 is shown in FIG.
Every) interrupt processing routine.

As shown in FIG. 13, the microcomputer 19 is initialized at step 101 at the time of startup, and various processes are repeated at step 102. On the other hand, when a pulse signal from the vehicle speed sensor 17 is input, an interruption occurs in the microcomputer 19,
As shown in FIG. 4, the microcomputer 19 calculates and stores the vehicle speed pulse width from the time at which the last pulse interruption occurred and the time at which this interruption occurred in step 201.

When 5 ms elapses during the execution of FIGS. 13 and 14, an interrupt occurs, and the microcomputer 19 calculates the vehicle speed V based on the vehicle speed pulse processing in step 300, as shown in FIG.

Next, at step 400, the steering wheel angle θf,
The steering torque T and yaw rate Wa are input and stored in the memory. Next, the steering torque T input in step 500 is corrected.

This is because the steering torque T detected in step 400 has a so-called self-aligning torque that tends to return the steering wheel 26 due to the force applied to the tire from the road surface when the steering wheel 26 is turned.
This is because the torque is different from the torque for the driver to rotate the handle 26. The self-aligning torque is
Since it changes depending on the vehicle speed V and the steering wheel angle θf, a map having the vehicle speed V and the steering wheel angle θf as parameters as shown in FIG. 16 is prepared in advance, and the map at that time is set according to the state at that time.
The self-aligning torque is calculated and subtracted from the detected steering torque to obtain the torque component Tc at which the driver tries to rotate the steering wheel.

Next, in step 600, the microcomputer 1
9 calculates the rear wheel actual steering angle θr by the rear wheel steering sensor 12. In step 700, the vehicle speed V and the steering wheel angle θ
The target rear wheel steering θr is calculated from f, the corrected steering torque Tc, and the yaw rate Wa. Details of this step 700 will be described with reference to the flowchart of FIG.

First, at step 701, the steering wheel angle θ
The target rear wheel steering angle feedforward term θ _rp for feedforward is calculated from _f and the vehicle speed V by the following equation.

[0023]

## EQU1 ## θ _rp = K ₁ (v) θ _f where K ₁ (v) is a coefficient that changes according to the vehicle speed V.

Next, at step 702, the basic target yaw rate W _aB , which is the target yaw rate, is calculated from the steering wheel angle θ _f and the vehicle speed V using a map prepared in advance. In step 703, the corrected target yaw rate W _aC is calculated in order to correct the basic target yaw rate W _aB calculated in step 702 in order to improve the transient response of steering. Specifically, the corrected target yaw rate W _aC is calculated by the following equation using the vehicle speed V and the corrected steering torque T _C.

[0025]

## EQU2 ## W _aC = K ₂ (v) _{T C} where K ₂ (v) is a coefficient that changes according to the vehicle speed V.

In step 704, the basic target yaw rate W _aB and the corrected target yaw rate W _aC are added and corrected to obtain the target yaw rate W _a ^* . Next, at step 705, the yaw rate feedback term θr of the target rear wheel steering angle is calculated from the difference between the target yaw rate Wa ^* and the actual yaw rate Wa ^.
Calculate _Y. Next, at step 706, the target rear wheel steering angle feedforward term θr _P and the target rear wheel steering angle yaw rate feedback term θr _Y are added to obtain the target rear wheel steering angle θc.

If the target rear wheel steering angle θc can be calculated by the above procedure, the program proceeds to step 800 of FIG. 18, and both are calculated based on the target rear wheel steering angle θc and the actual rear wheel steering angle θr. A publicly known rear wheel positioning servo calculation is performed to eliminate the difference between the two, a current command value signal If is calculated in step 900 based on the calculation result, and the current command value signal If is output to the drive circuit 24 to drive the servo motor 2.

As described above, in this embodiment, in the target yaw rate feedback control, the basic target yaw rate W _aB
Is corrected based on the vehicle speed V and the corrected steering torque T _C , so that there is no time delay in the vehicle behavior as when the differential value of the steering wheel angle is obtained.
The transient response of steering can be improved. Further, in the present embodiment, the steering torque is corrected from the vehicle speed V and the steering wheel angle θ _f, and the corrected steering torque T _c is used as the basic target yaw rate W.
Since it is used for the correction of _aB , it is not affected by road surface friction or road surface reaction force unlike when the rear wheel control is performed only based on the steering torque.

In this embodiment, the vehicle speed sensor 17 corresponds to the vehicle speed detecting means, the front wheel steering angle sensor 15 corresponds to the steering angle detecting means, and step 700 of FIG. 15 corresponds to the target wheel steering angle calculating means. The steering torque sensor 25 corresponds to torque detection means, step 500 in FIG. 15 corresponds to torque correction means, and 704, 705, and 706 in FIG. 17 correspond to target wheel steering angle correction means.

The present invention is not limited to the target yaw rate feedback control as in the above embodiment, but the basic target rear wheel steering angle may be corrected as shown in the control block diagram of FIG. 19, for example. Good. Further, not only the steering control of the rear wheels but also the auxiliary control of the front wheels may be applied.

[0031]

As described in detail above, according to the present invention, the steering torque detected by the torque detecting means is corrected by a parameter according to the steering angle of the steering wheel and the vehicle speed, and the corrected steering torque is corrected according to the corrected steering torque. Since the target wheel steering angle is corrected, there is an excellent effect that the transient response of steering can be improved without being affected by the resolution of the steering angle detecting means.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the overall configuration of an embodiment.

FIG. 2 is a schematic view showing a pattern in which a steering torque sensor 25 is attached to a steering wheel.

3 is a cross-sectional view of a main part of FIG.

FIG. 4 is a schematic diagram showing a detection unit of a steering torque sensor 25.

5 is a plan view of a main part of a steering torque sensor 25. FIG.

6 is a cross-sectional view taken along the line AA of FIG.

7 is a bottom view of the steering torque sensor 25. FIG.

8 is a sectional view taken along line BB of FIG.

9 is an enlarged view of a main part of FIG.

FIG. 10 is a shape diagram showing the shape of an elastic body.

FIG. 11 is a shape diagram showing the shape of an elastic body.

FIG. 12 is a block diagram showing an electrical configuration of the control device 3.

FIG. 13 is a flowchart showing a main processing routine of the microcomputer 19.

FIG. 14 is a flowchart showing vehicle speed pulse processing.

FIG. 15 is a flowchart showing an interrupt processing routine.

FIG. 16 is a map diagram for obtaining a steering torque T _c .

FIG. 17 is a flowchart showing detailed processing of step 700.

FIG. 18 is a control block diagram showing an operation by the control device 3.

FIG. 19 is a control block diagram showing the operation of another embodiment.

[Explanation of symbols]

 3 Control device 17 Vehicle speed sensor 25 Steering torque sensor

Claims (1)

[Claims] 1. A vehicle speed detecting means for detecting a vehicle speed, a steering angle detecting means for detecting a steering angle of a steering wheel, and a target wheel steering angle calculation for calculating a target wheel steering angle according to the vehicle speed and the steering angle of the steering wheel. A steering control device for a vehicle that controls the wheel steering angle to match the target wheel steering angle, the steering torque detecting means detecting steering torque, and the steering torque detected by the torque detecting means. And a target wheel steering angle correction means for correcting the target wheel steering angle according to the corrected steering torque corrected by the torque correction means. A steering control device for a vehicle, comprising: