JP3018828B2 - Yaw rate control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a yaw rate control apparatus for performing feedback control based on a yaw rate generated in a vehicle, and more particularly to a yaw rate control apparatus for suppressing the generated yaw rate.

[0002]

2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 3-169772, there is a yaw rate control device which detects a yaw rate of a vehicle by a yaw rate detecting means and suppresses the yaw rate based on the detected yaw rate. . Further, assuming that the vehicle height most suitable for traveling on a general road is the reference vehicle height, the suspension of the vehicle is generally set so that an alignment change such as bound / rebound becomes optimal at the reference vehicle height. For example, in the case of a double wishbone suspension, the toe change, tread change, and camber change due to the suspension rebound are set to be optimal at the reference vehicle height. Therefore, the control amount per unit time of the above yaw rate control device is also set so that the running stability is optimal when the vehicle is running at the reference vehicle height.

[0003]

However, when a vehicle height adjustment device is provided, for example, when the vehicle height becomes a vehicle height other than the reference vehicle height, the neutral position of the stroke of the suspension changes, and alignment such as bounding and rebounding is performed. The change is no longer optimal and running stability deteriorates. At that time, even if the yaw rate is controlled by the yaw rate control device, the control amount per unit time is set to be optimal at the reference vehicle height, and the control amount per unit time is the same as the reference vehicle height. Even if the yaw rate is suppressed, the control amount per unit time is small, so that the yaw rate of the vehicle cannot be completely suppressed. Therefore, there is a problem that running stability is not improved as compared with the case of the reference vehicle height.

[0004] The present invention has been made to solve the above problem, and when the vehicle height is other than the reference vehicle height, the control amount per unit time is made larger than when the vehicle height is at the reference vehicle height.
It is an object to prevent deterioration of controllability in a yaw rate control device.

[0005]

As shown in FIG. 1, the configuration of the present invention for achieving the above object comprises a yaw rate control mechanism M1 for controlling a yaw rate of a vehicle, and a yaw rate detecting means for detecting a yaw rate of the vehicle. A yaw rate control device including M2 and feedback control means M3 for controlling a yaw rate control mechanism with a predetermined control amount per unit time in a direction for suppressing the yaw rate detected by the yaw rate detection means detects a vehicle height. The vehicle height detecting means M4, a vehicle height determining means M5 for determining whether or not the vehicle height detected by the vehicle height detecting means M4 is a predetermined reference vehicle height, and the vehicle height determined by the vehicle height determining means M5. When it is determined that the vehicle height is not the reference vehicle height, the feedback control means M3
And a correcting means M6 for making the magnitude of the control amount per unit time larger than that at the reference vehicle height.

[0006]

According to the yaw rate control device having the above structure, when the yaw rate control mechanism is controlled with a predetermined control amount per unit time in the direction of suppressing the yaw rate detected by the yaw rate detection means, the yaw rate is detected by the vehicle height detection means. When the vehicle height is determined to be other than the reference vehicle height by the vehicle height determination means, the magnitude of the control amount per unit time of the feedback control means is made larger by the correction means than when the reference vehicle height is used.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 1 is a block diagram illustrating the present invention, and FIG. 2 is a diagram schematically illustrating an entire four-wheel steering vehicle according to the embodiment. FIG. 3 is a flowchart of the vehicle height adjustment control;
FIG. 4 shows a flowchart of the yaw rate control.

As shown in FIG. 2, the four-wheel steering vehicle includes a front wheel steering mechanism A for steering left and right front wheels FW1 and FW2, a rear wheel steering mechanism B for steering left and right rear wheels RW1 and RW2, and a rear wheel steering mechanism. A feedback control means C for electrically controlling the mechanism B and a vehicle height adjusting device D are provided.

The front wheel steering mechanism A is a well-known rack and pinion type power steering device. This device has a steering wheel 11, which is connected to a pinion gear 13 via a steering shaft 12. The pinion gear 13 meshes with the rack shaft 14, and the steering handle 1
1 is converted into a reciprocating motion of the rack shaft 14. Left and right front wheels FW1, FW2 are steerably connected to both ends of the rack shaft 14 via left and right tie rods 15a, 15b and left and right knuckle arms 16a, 16b. And
When the steering wheel 11 rotates, the rack shaft 14 is displaced in the axial direction, and the left and right front wheels FW1 and FW2 are steered.

The rear wheel steering mechanism B has a relay rod 31 that is displaced in the axial direction and steers the left and right rear wheels RW1, RW2 similarly to the rack shaft 14. At both ends of the relay rod 31, left and right tie rods 32a, 32b and left and right knuckle arms 33a, 33, as in the case of the front wheel steering mechanism A described above.
Left and right rear wheels RW1, RW2 are steerably connected via 3b. The relay rod 31 is supported by a housing 34 supported by the vehicle so as to be displaceable in the axial direction.
The cylinder 35 is divided into left and right oil chambers 35b and 35c by a piston 35a fixed to the relay rod 31. In these left and right oil chambers 35b and 35c, springs 36a and 36b are incorporated so as to penetrate the relay rod 31 in a preloaded state.
The springs 36a and 36b urge the relay rod 31 to the neutral position by their elasticity.

A through hole 37a1 is provided at the right end of the valve sleeve 37a, and a lever 41 passes through the through hole 37a1. An intermediate portion of the lever 41 is provided with a spherical nodal protrusion 41a, and the lever 41 is tiltably and slidably engaged with the inner circumferential surface of the through hole 37a1 on the outer circumferential surface of the nodal protrusion 41a. I have. The lower end of the lever 41 is rotatably fitted in an annular groove 35a1 provided on the outer periphery of the piston 35a and slidably in the vehicle front-rear direction, and the upper end of the lever 41 is rotatably connected to the pin 42. Have been.

Both ends of the pin 42 enter the support holes 34a and 34b provided in the housing 34 so as to be able to advance and retreat and to be unable to rotate. Also, the rack teeth 4
2a are formed, and the stepping motor 4 is mounted on the rack teeth 42a.
The worm 44 fixed to the rotation shaft 3 is meshed.
In this case, when the step motor 43 rotates in the positive (or negative) direction, the pin 42 is displaced to the right (or left), and the lever 41 is slid to move the relay rod 3.
1. Left and right tie rods 32a, 32b, knuckle arm 3
The left and right rear wheels RW1, RW2 are steered via 3a, 33b.

The hydraulic oil from the hydraulic pump 38 driven by the engine 18 is supplied to the left oil chamber 35 b of the cylinder 35.
(Or the right oil chamber 35c), and the hydraulic oil in the right oil chamber 35c (or the left oil chamber 35b) of the cylinder 35 is discharged to the reservoir 23. And the left oil chamber 35b,
The steering force is assisted by the difference in the hydraulic pressure of the right oil chamber 35c.

The vehicle height adjusting device D is shown in FIG. There is a compressor 202 driven by a motor 201 to compress air from an inlet 202a.
Is connected to an accumulator 220 for storing compressed air. The accumulator 220 is connected to a well-known air suspension 228 via a lift valve 226. Further, the air suspension 228 includes a down valve 232.
Is also connected. The ascending valve 226 and the descending valve 232 are switched between open and closed by an actuator (not shown) based on a signal from the drive circuit 56. And
The lift valve 226 is opened by the actuator,
When the descending valve 232 is closed, the air suspension 228
The compressed air in the accumulator 220 is distributed therein, and the vehicle height rises. Also, the ascending valve 226 is closed, and the descending valve 2
When the valve 32 is opened, the air in the air suspension 228 is discharged to the atmosphere, and the vehicle height decreases.

A vehicle height sensor 51 as a vehicle height detecting means includes:
A signal corresponding to a high state (high vehicle height) is output when the vehicle height is high with respect to a reference vehicle height range of a predetermined width set in advance, and when the vehicle height is within the reference vehicle height range, the reference state ( A signal corresponding to the reference vehicle height) is output. When the vehicle height is lower than the reference vehicle height range, a signal corresponding to a low state (low vehicle height) is output.

The vehicle height selection switch 210 has a manual mode in which the occupant can select a vehicle height, a standard vehicle height, and a low vehicle height, and an automatic mode in which the microcomputer 55 automatically selects the vehicle height based on the vehicle speed. And outputs two kinds of signals to the microcomputer 55, that is, the selected mode and the vehicle height selected by the occupant or the microcomputer 55.

The vehicle speed sensor 52 detects the vehicle speed V by measuring the rotation speed of the output shaft of a transmission (not shown).
A signal representing the vehicle speed V is output.

The G sensor 57 detects the vertical G of the vehicle,
And outputs a signal corresponding to the magnitude of.

The vehicle height sensor 51, vehicle speed sensor 52, G
The sensor 57 is connected to a microcomputer 55. The microcomputer 55 includes a ROM 55b, a CPU 55c, and a RAM 55d connected to a bus 55a, respectively.
And I / O 55e (input / output interface). The ROM 55b stores programs corresponding to the flowcharts of FIGS. A drive circuit 56 is connected to the microcomputer 55. The drive circuit 56 controls the step motor 43, the motor 201, the ascending valve 226, and the descending valve 232 according to a rotation control signal from the microcomputer 55.

Next, the processing for adjusting the vehicle height performed in the microcomputer 55 will be described with reference to the flowchart of FIG.

First, at step 101, the vehicle height sensor 5
1. The signals from the vehicle height selection switch 210, the vehicle speed sensor 52, and the G sensor 57 are read via the I / O 55e, and it is determined in step 102 whether the vehicle height selection switch 210 is in the manual mode. When it is determined in step 102 that the vehicle height selection switch 210 is in the manual mode, the vehicle height selection switch 2 is determined in step 200.
The required vehicle height is set as the required vehicle height, and
Move to step 108. On the other hand, if it is determined in step 102 that the vehicle height selection switch 210 is not in the manual mode, that is, it is in the automatic mode,
Move on to In step 103, it is determined whether the vehicle speed is equal to or higher than 80 km / h. If it is determined in step 103 that the vehicle speed is 80 km / h or more, step 1
In step 04, the required vehicle height is reduced. Then, the process proceeds to step 108. In step 103, the vehicle speed is 80 k.
If it is determined that the difference is not more than m / h, the process proceeds to step 105. When it is determined in step 105 that the road surface is a bad road from the detected upper and lower G, in step 106, the required vehicle height is increased. Then, the process proceeds to step 108. If it is determined in step 105 that the road surface is not a bad road, in step 107, the required vehicle height is set to the reference vehicle height. In step 108, it is determined whether or not the current vehicle height matches the required vehicle height. If it is determined that the required vehicle height matches the current vehicle height based on the determination result, step 109
Outputs a signal to the ascending valve 226 to close the ascending valve 226.
Is closed, and a signal of closing is output to the descending valve 232, so that the descending valve 2
Close 32. Then, the process returns to step 101. If it is determined in step 108 that the required vehicle height does not match the current vehicle height, it is determined in step 110 whether the current vehicle height is lower than the required vehicle height. If it is determined in step 110 that the current vehicle height is lower than the required vehicle height, an open signal is output to the ascending valve 226 in step 111, and the ascending valve 232 is opened and the accumulator 22 is opened.
0 flows into the air suspension 228, and outputs a close signal to the descending valve 232 to output the signal to the descending valve 232.
Close and raise the vehicle height. Then, the process returns to step 101. When it is determined in step 110 that the current vehicle height is not lower than the required vehicle height, that is, the current vehicle height is higher than the required vehicle height, in step 112, a signal to close the ascending valve 226 is sent to the ascending valve 226. Then, the ascending valve 226 is closed, an open signal is output to the descending valve 232, and the descending valve 232 is opened to release the air in the air suspension 228 to the atmosphere. Then, the process returns to step 101.

In this manner, the vehicle height is adjusted to a reference vehicle height suitable for traveling on a general road, a low vehicle height lower than a reference vehicle height suitable for high-speed traveling, and suitable for traveling on unpaved roads. The height can be changed to a higher height than the reference height.

The feedback control means C will be described. The yaw rate sensor 53 serving as the yaw rate detecting means M3 detects a rotational angular velocity around a vertical axis of the vehicle, that is, a yaw rate ωy
And outputs the signal. Rear wheel steering angle sensor 5
4 detects the rotation angle of the rotation shaft of the step motor 43 and outputs a signal representing the rear wheel steering angle θr. Note that the yaw rate ωy and the rear wheel steering angle θr are each positive in the right rotation direction and negative in the left rotation direction. Yaw rate sensor 5
3. The rear wheel steering angle sensor 54 is a microcomputer 55
It is connected to the. As described above, the microcomputer 55 includes the ROM 55b connected to the bus 55a,
It comprises a CPU 55c, a RAM 55d and an I / O 55e (input / output interface). The ROM 55b stores a program corresponding to the flowcharts of FIGS. 3 and 4, and stores a coefficient K described later in the form of a table. A drive circuit 56 is connected to the microcomputer 55.

Next, the processing performed by the microcomputer 55 will be described with reference to the flowchart of FIG.

In step 113, the vehicle speed, vehicle height, ωy, θ, θr are read from signals from the vehicle height sensor 51, vehicle speed sensor 52, yaw rate sensor 53, and rear wheel steering angle sensor 54. If it is determined in step 114 that the vehicle height is the reference vehicle height, the coefficient K is set in the map A in step 115.
When the vehicle height is other than the reference vehicle height, the coefficient K is calculated from the map A2 in step 116.
5 and 6, the maps A1 and A2 are tables for determining the value of the coefficient K according to the vehicle speed. Since the map A2 is larger than the map A1, the map A2 uses the yaw rate control device. Is controlled, the control amount per unit time becomes larger than that of the map A1. Then, based on the coefficient K, the following equation 1 is calculated in step 117, and the target rear wheel steering angle θr * is calculated.

[0026]

After calculating the target rear wheel steering angle θr *, at step 118, the current rear wheel steering angle θr is subtracted from the target rear wheel steering angle θr * to obtain the left and right rear wheel steering angle θr *. The rear wheel steering amount θr * -θr per unit time to be steered of the wheels RW1 and RW2 (control amount per unit time) is calculated, and the step corresponding to the rear wheel steering amount θr * -θr per unit time is calculated. The rotation control signal for the motor 43 is transmitted to the drive circuit 5 via the I / O 55e.
6 is output.

The drive circuit 56 supplies a drive pulse corresponding to the rotation control signal to the step motor 43, and the step motor 43 rotates the worm 44 by an amount corresponding to the drive pulse. In this case, the rear wheel steering amount θ per unit time
If the rotation control signal corresponding to r * -θr is positive, the step motor 43 rotates forward, the pin 42 is displaced rightward, the relay rod 31 is displaced leftward, and the left and right rear wheels R
W1 and RW2 are steered to the right. On the other hand, when the relay rod 31 is displaced leftward, the lower end of the lever 41 is displaced leftward with its upper end serving as a fulcrum. The left and right rear wheels RW1 and RW2 are steered to the right by an amount based on the rear wheel steering amount θr * −θr per unit time from the past state, and the steering angle θr becomes equal to the target steering angle θr *,
The yaw rate of the vehicle is suppressed.

Further, the rear wheel steering amount θr *-
If the rotation control signal corresponding to θr is negative, the stepping motor 43 rotates negatively and the pin 42 is displaced leftward, and conversely, the left and right rear wheels RW1, RW2 are shifted from the past state. Rear wheel steering amount per unit time θr * −θ
In this case, the steering angle θr is equal to the target rear wheel steering angle θr *.
The yaw rate of the vehicle is suppressed. In the present embodiment, means for increasing the rear wheel steering amount θr * −θr per unit time is used in order to increase the control amount per unit time when suppressing the yaw rate.
Means for increasing the number of repetitions of steps 117 and 118 of the feedback control means per unit time as compared with the reference vehicle height, and making the rotation speed of the step motor 43 faster than that at the reference vehicle height to increase the number of times per unit time. Means for increasing the control amount, coefficient K calculated by map A1
Means for increasing the control amount per unit time by adding a predetermined number to

Next, the operation and effect of the embodiment will be described.
Alignment changes such as bound and rebound of the suspension of this embodiment are set to be good at the most frequently used reference vehicle height. Further, the map A1 is set so that the rear wheel steering amount θr * −θr per unit time by the yaw rate control device is good when the reference vehicle height is set. Therefore, when the vehicle height is the reference vehicle height, the running stability is improved.

When the vehicle height becomes a vehicle height other than the reference vehicle height by the vehicle height adjusting device D, the neutral position of the suspension stroke changes, the neutral position of the suspension stroke changes, and the rebound alignment is adjusted. The change will not be optimal. However, in the embodiment, when the vehicle is at a position other than the reference vehicle height, the rear wheel steering amount θr * −θr per unit time is increased based on the map A2 to suppress the yaw rate. Is kept.

The relationship between this embodiment and the claims will be described. The yaw rate control mechanism is the rear wheel steering mechanism B, the yaw rate detecting means is the yaw rate sensor 53, and the feedback control means is steps 117 and 11 in the flowchart of FIG.
8. The vehicle height detecting means is the vehicle height sensor 51, the vehicle height determining means is step 114 in the flowchart of FIG.
Correspond to step 116 of the flowchart of FIG.

In this embodiment, the yaw rate control mechanism is a rear wheel steering control apparatus. However, the yaw rate control mechanism is not limited to the rear wheel steering control apparatus. For example, the yaw rate control mechanism controls the steering angle of the front wheels to control the yaw rate. , A device that controls the yaw rate by controlling the braking force of each wheel, a device that controls the yaw rate by controlling the driving force of each of the right and left rear wheels, and the yaw rate by controlling the driving force before and after 4WD It may be a device or the like for suppressing the pressure.

Further, the present invention can be applied to a vehicle having no vehicle height adjusting device because the vehicle height changes depending on the load.

[0034]

According to the yaw rate control device of the present invention,
At a vehicle height other than the reference vehicle height at which the running state of the vehicle becomes unstable, the yaw rate is controlled with a larger control amount per unit time than at the reference vehicle height, so even at a vehicle height other than the reference vehicle height This has the effect of improving running stability.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a schematic diagram of a four-wheel steering vehicle showing an embodiment of the present invention.

FIG. 3 is a flowchart showing a program for controlling vehicle height adjustment executed by the microcomputer 55 of FIG. 2;

FIG. 4 is a flowchart showing a yaw rate control program executed by the microcomputer 55 of FIG. 2;

FIG. 5 is a map for calculating a coefficient K at a reference vehicle height.

FIG. 6 is a map for calculating a coefficient K at a reference vehicle height.

[Explanation of symbols]

 A front wheel steering mechanism B rear wheel steering mechanism C feedback control means D vehicle height adjustment device FW1, FW2 front wheel RW1, RW2 rear wheel 51 vehicle height sensor 52 vehicle speed sensor 53 ・ ・ Yaw rate sensor 54 ・ ・ Rear wheel steering angle sensor 55 ・ ・ Microcomputer

Claims (1)

(57) [Claims] 1. A yaw rate control mechanism for controlling a yaw rate of a vehicle, a yaw rate detecting means for detecting a yaw rate of the vehicle, and a yaw rate control with a predetermined control amount per unit time in a direction for suppressing the yaw rate detected by the yaw rate detecting means. A yaw rate control device including a feedback control unit that controls a mechanism, a vehicle height detection unit that detects a vehicle height, and determines whether a vehicle height detected by the vehicle height detection unit is a predetermined reference vehicle height. Vehicle height determining means for determining, and correcting the control amount per unit time of the feedback control means to be larger than the reference vehicle height when the vehicle height determining means determines that the vehicle height is not the reference vehicle height. And a yaw rate control device.