JP3085059B2 - Vehicle characteristic control device for four-wheel steering vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle characteristic control apparatus for a four-wheel steering vehicle equipped with a variable damping force shock absorber capable of assisting at least rear wheels according to a steering angle or the like. An effective fail-safe process can be performed when an abnormality occurs in any of the steering control systems.

[0002]

2. Description of the Related Art A conventional vehicle characteristic control device for a four-wheel steering vehicle is disclosed in, for example, Japanese Patent Application Laid-Open No.
There is one described in No. 5969. This conventional example includes a suspension capable of switching and controlling suspension characteristics such as a spring constant, a damping force, and a roll rigidity, an auxiliary steering device for auxiliary steering of at least one of a front wheel and a rear wheel, and an auxiliary steering device for adjusting a steering angle and the like. In a four-wheel steering vehicle provided with a steering control means for controlling the suspension characteristic change, the suspension characteristic change detection means for detecting a change in the suspension characteristic, and the steering control means according to a characteristic detection value of the suspension characteristic change detection means. By providing an auxiliary steering amount correcting means for sewing the auxiliary steering amount, the steering characteristics of the four-wheel steering vehicle can be maintained in an appropriate state regardless of changes in the suspension characteristics.

[0003]

However, in the above-mentioned conventional vehicle characteristic control apparatus for a four-wheel steering vehicle, a change in steering stability due to a change in damping force characteristic is corrected, and the initial steering characteristic is reduced. Just trying to maintain,
Since both the damping force control characteristic and the steering characteristic are not linked and controlled in accordance with the traveling state of the vehicle, both the damping force characteristic and the steering characteristic are independently controlled, so the damping force control system or When an abnormality occurs in any of the steering control systems, it is general to respond by suspending the control of the control system in which the abnormality has occurred, and thus simply stopping the control of the abnormality control system. However, if an abnormality occurs in the four-wheel steering control system, the vehicle only returns to the two-wheel steering state, so that the steering stability decreases. Similarly, if an abnormality occurs in the damping force control system, the riding comfort is reduced. There is an unsolved problem that worsens suddenly.

Accordingly, the present invention has been made in view of the above-mentioned unsolved problems of the prior art, and is intended to suppress a sudden change in vehicle characteristics when an abnormality occurs in any of a plurality of vehicle characteristic control systems. It is an object of the present invention to provide a vehicle characteristic control device for a four-wheel steering vehicle that can perform the following.

[0005]

In order to achieve the above object, a vehicle characteristic control apparatus for a four-wheel steering vehicle according to the first aspect of the present invention includes a suspension having a variable damping force shock absorber and an auxiliary steering of at least a rear wheel. An auxiliary steering device; damping force control means for controlling the damping force of the variable damping force shock absorber in accordance with vertical movement of the vehicle body; and steering control means for controlling the auxiliary steering device in accordance with a steering angle or the like. In a vehicle characteristic control device for a four-wheel steering vehicle, first abnormal state detecting means for detecting an abnormal state of a control system including a front wheel side variable damping force shock absorber, and control including a rear wheel side variable damping force shock absorber A second abnormal state detecting means for detecting an abnormal state of the system, a third abnormal state detecting means for detecting an abnormal state of the control system including the rear-wheel auxiliary steering device, Atmospheric state detecting means, when an abnormality is detected in any of the second abnormal state detecting means and the third abnormal state detecting means comprises an abnormality control processing means for compensating the vehicle characteristics in the rest of the control system, the The abnormality control processing means includes:
The first abnormal state detecting means and the second abnormal state detecting means
When an error is detected in any of the control systems
Damping force variable shock absorber fixed in high damping force state
And increase the yaw rate control gain of the auxiliary steering system.
It is configured to control to control gain
It is assumed that.

According to a second aspect of the present invention, there is provided a vehicle characteristic control device for a four-wheel steering vehicle having a variable damping force shock absorber.
Suspension and at least auxiliary steering for rear wheels
Auxiliary steering device and reduction of the damping force variable shock absorber
Damping force control means for controlling the damping force according to the vertical movement of the vehicle body
And steering for controlling the auxiliary steering device according to a steering angle or the like.
Vehicle characteristic control device for a four-wheel steering vehicle having control means
Including the front wheel side damping force variable shock absorber
First abnormal state detecting means for detecting an abnormal state of the control system
And control including a variable damping force shock absorber on the rear wheel side
Second abnormal state detecting means for detecting an abnormal state of the system;
Detects an abnormal state of the control system including the wheel-side auxiliary steering device.
3 means for detecting an abnormal state, and the first abnormal state detecting means
Step, second abnormal state detecting means and third abnormal state detecting means
When an abnormality is detected in one of the steps, the remaining control system
Abnormality control processing means for compensating for both characteristics;
The control processing means detects an abnormality with the third abnormal state detecting means
When the control of the steering system in which the abnormality occurred
Variable shock absorbers for the front and rear wheels
It is configured to control the damping force of
It is characterized by the following.

[0007]

[0008]

In the vehicle characteristic control apparatus for a four-wheel steering vehicle according to the first aspect, the variable damping force shocks on the front wheel side and the rear wheel side are provided.
When an error occurs in any of the absorbers,
High damping of variable damping force shock absorber of generated control system
Improving steering stability by fixing to the force state
In addition, the yaw rate control gain of the auxiliary steering
By improving the steering stability, the vehicle characteristics
A sudden change can be suppressed.

Further, in the vehicle characteristic control device for a four-wheel steering vehicle according to the second aspect , an abnormality occurs in the four-wheel steering control system.
When the vehicle is in
Steering by controlling the variable force shock absorber to the high damping force side
Improves stability and suppresses sudden changes in vehicle characteristics.

[0010]

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic configuration diagram showing one embodiment of the present invention, in which a variable damping force shock absorber 3 constituting a suspension device is provided between each wheel 1FL-1RR and the vehicle body 2.
FL to 3RR are arranged, and a stepping motor 41 for switching the damping force of these variable damping force shock absorbers 3FL to 3RR is provided.
FL to 41RR are controlled by a control signal from a controller 4 described later.

The front wheels 1FL, 1RR are connected to knuckles (not shown) at one ends of tie rods 73L, 73R, and the other ends of the tie rods 73L, 73R are connected to a rack shaft 74a of a rack and pinion type steering device 74.
A steering shaft 75 of the rack and pinion type steering device 74 is connected to a steering wheel 76, and by steering the steering wheel 76, the front wheels 1FL, 1RR are steered in the same direction as the steering direction.

On the other hand, the rear wheels 1RL, 1RR are connected to a knuckle (not shown) via a tie rod 78L, 78R, a piston rod 79a of a rear wheel assist steering cylinder 79. The rear wheels 1RL and 1RR are connected to the output side of a differential device 81 via axles 80L and 80R, and the input side of the differential device 81 is connected to a transmission 84 to which the rotational force of an engine 83 is input via a propeller shaft 82. And is rotationally driven.

The rear wheel assist steering cylinder 79 is provided with pressure chambers 89L, 89R defined by a piston 79b.
Are connected to a protruding side of a hydraulic pump 88 which is rotationally driven by an engine 83 via an unload valve 87, and drain ports are connected to each other and connected to an oil tank 89 via an unload valve 87. I have. Reference numeral 90 denotes an accumulator for accumulating the line pressure. Here, a rear wheel steering device is constituted by the rear wheel assist steering cylinder 79, the servo valve 85, the unload valve 87, the hydraulic pump 88, the oil tank 89, and the accumulator 90.

Variable damping force shock absorber 3FL-3RR
Is a twin-tube gas-filled strut type having a cylinder tube 7 composed of an outer cylinder 5 and an inner cylinder 6 as shown in FIGS. 8 define upper and lower pressure chambers 9U and 9L. 4 to 7, the piston 8 has a cylindrical lower half 11 having a sealing member 9 molded on the outer peripheral surface thereof in sliding contact with the inner cylinder 6 and having a center opening 10 on the inner peripheral surface. The lower half 11 has an upper half 12 fitted therein.

The lower half body 11 has an extension oil passage 13 penetrating vertically and a sealing member 9 extending downward from the upper surface side.
The hole 14 a having a diameter larger than that of the extension-side oil flow path 13 and extending from the outer peripheral surface of the cylindrical body 11 to the hole 14.
a, a pressure-side oil flow path 14 formed of a hole 14b drilled in communication with the bottom of the hole a, annular grooves 15U, 15L formed at the upper and lower open ends of the central hole 10, and formed on the upper surface side. A long groove 16 communicating with the annular groove 15U and the expansion-side oil flow path 13 and a long groove 17 formed on the lower surface side and communicating with the annular groove 15L are formed. The long groove 17 is closed by the extension-side disk valve 18, and the upper end side of the compression-side oil flow path 14 is closed by the compression-side disk valve 19.

The upper half 12 has a small-diameter shaft portion 21 inserted into the center opening 10 of the lower half body 11 and the shaft portion 2.
The lower end face of the small-diameter shaft portion 21 is formed at the center of the small-diameter shaft portion 21 and the large-diameter shaft portion 22. 23a extending from the side to the middle of the large-diameter shaft portion 22, and a hole 23b communicating with the upper end of the hole 23a and having a smaller diameter than the hole 23a.
And a hole 23c having a larger diameter than the hole 23c communicating with the upper end side of the hole 23b. The through hole 23 is formed at a position facing the annular grooves 15U and 15L of the small diameter shaft 21 respectively. Pair of through holes 24 penetrating the inner peripheral surface side in the direction
a, 24b and 25a, 25b are drilled, and the upper end side of the hole 23a of the large-diameter shaft portion 22 is connected to the arc-shaped groove 2 communicating therewith.
6 is formed, and an L-shaped pressure-side oil flow path 27 communicating with the arc-shaped groove 26 and the lower end face is formed.
Is blocked by

The lower half 11 and the upper half 12 are positioned below the lower half 11 of the small-diameter shaft 21 with the small-diameter shaft 21 inserted into the central opening 10 of the lower half 11. The nut 29 is screwed into the lower end protruding from the nut, and the nut 29 is tightened to be integrally connected. Further, a cylindrical valve body 31 whose upper end is closed in a hole 23a of the upper half body 12 and constitutes a variable throttle is rotatably disposed. As shown in FIG. 4, the upper half 1
2, a through-hole 32 is formed at a position facing the arc-shaped groove 26 of the large-diameter shaft portion 22 so as to reach the inner peripheral surface in the radial direction, and the small-diameter shaft of the upper half body 12 as shown in FIGS. A communication groove 33 is formed in the outer peripheral surface corresponding to the space between the through holes 24a and 25a of the portion 21, and further, as shown in FIG. 6, the through hole 24b of the small diameter shaft portion 21 of the upper half body 12 is formed.
An elongated hole 34 extending in the axial direction is formed in the outer peripheral surface corresponding to the area between the inner peripheral surface and the inner peripheral surface side.
Then, the positional relationship between the through hole 32, the communication groove 33, and the long hole 34 is selected so as to obtain the damping force characteristic with respect to the rotation angle of the valve body 31 shown in FIG. 8, that is, the step angles of the step motors 41FL to 41RR described later. ing.

That is, for example, at the position A in FIG. 8, which is the maximum rotation angle position in the clockwise direction, as shown in FIG. 4, only the through hole 32 communicates with the arc-shaped groove 26, so that the piston 8 descends. For pressure side movement, lower pressure chamber 9L
A pressure-side flow path C1 (shown by a dashed line) passing through the orifice formed by the open end of the pressure-side oil flow path 14 and the pressure-side disc valve 19 toward the upper pressure chamber 9U, and a lower pressure chamber 9L.
Through the inner peripheral surface of the valve body 31, through hole 32, arc-shaped groove 2
6. A pressure-side flow path C2, shown by a broken line, which passes through the pressure-side oil flow path 27, passes through an orifice formed by the opening end thereof and the pressure-side disc valve 28, and goes to the upper pressure chamber 9U, and the piston 8 rises. For the extension side movement, the upper pressure chamber 9U passes through the long groove 16 and the extension side flow path 13 and passes through the orifice formed by the opening end and the extension side disc valve 18 to the broken line toward the lower pressure chamber 9L. Only the expansion side flow path T1 shown in the figure is formed, and a high damping force is generated on the expansion side, which rapidly increases in accordance with an increase in the piston speed, and a low damping force on the compression side is slightly increased in accordance with the increase in the piston speed. Generates damping force.

By rotating the valve body 31 in the counterclockwise direction from the position A, the communication groove 33 of the valve body 31 and the through holes 24a, 25a of the small diameter shaft portion 21 communicate with each other as shown in FIG. The opening area between the communication groove 33 and the through holes 24a and 25a gradually increases as the rotation angle increases. For this reason, as shown in FIG. 5 (a), when the piston 8 moves on the extension side, the long groove 16 and the annular groove 15 are arranged in parallel with the flow path T1.
U, the through-hole 24a, the communication groove 33, the through-hole 25a, the annular groove 15L, the long groove 17, and the lower pressure chamber 9 through the orifice formed by the long groove 17 and the pressure-side disc valve 18.
A flow path T2 toward L is formed, and the maximum value of the damping force gradually increases as the opening area between the communication groove 33 and the through holes 24a and 25a of the small diameter shaft portion 21 increases as shown in FIG. As shown in FIG. 5B, for the movement on the extension side, the state where the flow paths C1 and C2 are formed is maintained, so that the minimum damping force state is maintained.

Further, when the valve element 31 is turned counterclockwise to near the position B, as shown in FIG. 6, a state is established in which the through hole 24b, 25b of the valve element 31 is communicated by the elongated hole 34. Become. For this reason, as shown in FIG. 6A, the elongated groove 16, the annular groove 15U, the through hole 24a, the elongated hole 3 are arranged in parallel with the flow paths T1 and T2 with respect to the extension side movement of the piston 8.
4. Flow path T3 passing through hole 23a toward lower pressure chamber 9L
Is formed, the extension-side damping force becomes the minimum damping force state, and the piston 23 moves against the compression side in addition to the flow passages C1 and C2 as well as the hole 23a, the long hole 34, and the through hole 2
4b, the flow path C reaching the long groove 16 through the annular groove 15U
3, a flow path C4 is formed that reaches the long groove 16 through the hole 23a, the long hole 34, the through hole 25b, the annular groove 15L, the through hole 25a, the communication groove 33, the through hole 24a, and the annular groove 15U. As shown in FIG. 8, the minimum damping force state is maintained.

Further, when the valve element 31 is rotated counterclockwise, the opening area between the elongated hole 34 and the through holes 24b and 25b is reduced, and the elongated hole 34 and the through hole 24 are rotated at the rotation angle θ _B2.
7, the opening area between the through hole 32 and the arc-shaped groove 26 gradually decreases from the rotation angle θ _B2 . For this reason, between the rotation angle θ _B2 and the maximum rotation angle θ _{C in the} counterclockwise direction, the flow path T1 and T2 coexist for the movement of the piston 8 on the extension side, so that the minimum damping force state is set. On the contrary, when the piston 8 is moved on the pressure side, the opening area between the through hole 32 and the arc-shaped groove 26 is gradually reduced, so that the maximum damping force is gradually increased, and the valve body 31 is moved to the position. As shown in FIG. 7, when the piston reaches pressure C, the space between the through-hole 32 and the arc-shaped groove 26 is cut off.
The flow path from L to the upper pressure chamber 9U is only the flow path C1, and the pressure side is in a high damping force state.

On the other hand, a cylindrical piston rod 35 is fitted into the hole 23c of the upper half body 12, and the upper end of the piston rod 35 projects upward from the cylinder tube 7, as shown in FIG. The upper end side is the vehicle body side member 36.
Is fixed by a nut 39 via rubber bushes 38U and 38L to a bracket 37 attached to the piston rod 35, and the step motors 41FL to 41RR are mounted on the upper end of the piston rod 35 via a bracket 40 by the rotation shaft 41a.
The rotating shaft 41a and the above-described valve element 31 are connected by a connecting rod 42 loosely inserted into the piston rod 35. 43 is a bumper rubber. The lower end of the cylinder tube 7 is connected to a wheel-side member (not shown).

The controller 4 has, on its input side,
As shown in the figure, according to the vertical acceleration provided on the vehicle body side corresponding to each wheel position, the vertical acceleration detection values X _2FL ″ to X composed of analog voltages that are upwardly positive and downwardly negative are provided.
Vertical acceleration sensors 51FL to 51RR as vertical acceleration detecting means for outputting _2RR ", and an inductance which is built in, for example, the cover of each of the damping force variable shock absorbers 3FL to 3RR and which corresponds to the relative displacement between the vehicle body side member and the wheel side member. Relative displacement detection value X consisting of analog voltage due to change
_DFL (= X _2FL −X _1FL ) to X _DRR (= X _2RR −
X _1RR ), stroke sensors 52FL to 52RR as relative displacement detecting means, a vehicle speed sensor 53 for detecting a vehicle speed, a steering angle sensor 54S for detecting a steering angle of the steering wheel 76, and a rear wheel assist steering cylinder 79. A rear wheel steering angle sensor 54R for detecting a rear wheel steering angle by detecting a moving amount of the vehicle, and a yaw rate sensor 55 for detecting a yaw rate generated in the vehicle body are connected, and each of the damping force variable shock absorbers 3FL to The step motors 41FL to 41RR for controlling the damping force of 3RR and the servo valve 85 are connected.

The controller 4 comprises a microcomputer 56 having at least an input interface circuit 56a, an output interface circuit 56b, an arithmetic processing unit 56c and a storage unit 56d;
The vertical displacement detection values X _2FL ″ to X _2RR ″ of the _FL to _51RR are converted into digital values and supplied to the input interface circuit 56a, and the relative displacement detection values X of the A / D converters 57FL to 57RR and the stroke sensors 52FL to 52RR. input interface circuit 56a converts the _DFL to X _DRR to a digital value
An A / D converter 58FL~58RR supplied to the A / D converter 60S supplies the steering angle detection value theta _S of the steering angle sensor 54S is converted into a digital value to the input interface circuit 56a, the rear wheel steering angle Rear wheel steering angle detection value δ _{rd of} sensor 54R
Is converted to a digital value and the input interface circuit 56
an A / D converter 60R is supplied to a, and A / D converter 60Y is supplied to the input interface circuit 56a is converted into a digital value a yaw rate detection value Y _D of the yaw rate sensor 55, is output from the output interface circuit 56b A step control signal for each of the step motors 41FL to 41RR is inputted, and is converted into a step pulse to drive each of the step motors 41FL to 41RR, and a motor drive circuit 59FL to 59RR and a drive control output from the output interface circuit 56b. A drive circuit 61a for driving the servo valve 85 of the rear wheel steering device by the signals CS _ra and CS _rb ,
61b.

Here, the arithmetic processing unit 56c of the microcomputer 56 executes the processing of FIGS.
A vehicle body vertical velocity X _2FL '~X _2RR' obtained by integrating the vehicle body vertical acceleration detection value X _2FL "~X _2RR" input from the vertical acceleration sensor 51FL～51RR, stroke sensor 52FL
To 52RR, the relative displacement detection values X _DFL (= X _2FL -X _1FL ) to X _DRR (= X _2RR -X)
_1RR ), the damping force coefficient C for performing the skyhook control is determined based on the relative speeds X _DFL ′ to X _DRR ′, and the step motor 4 corresponding to the determined damping coefficient C is determined.
Calculates a target step angle theta _T of 1FL～41RR, this calculates the difference value between the target step angle theta _T and the current step angle theta _P, the motor driving circuit a step control amount corresponding to 5
And outputs the 9FL～59RR, calculates a front wheel steering angle [delta] _f based on the steering angle detected value theta _S of the steering angle sensor 54S, then the steering angle ratio k of the front and rear wheels based on the vehicle speed detection value V of the vehicle speed sensor 53 Is calculated based on the steering angle ratio k.
calculating a _r, difference value between the rear wheel steering angle [delta] _r and the rear wheel steering angle detected value [delta] _rd outputs a switching control signal CS _ra and CS _rb so as to zero, further on the front wheel side and rear wheel side An abnormal state of the control system of the damping force variable shock absorber and an abnormal state of the rear wheel steering system are detected, and when one of the control systems becomes abnormal, the vehicle characteristics of the abnormal control system are determined. Compensate with the remaining normal control system.

The storage device 56d stores the arithmetic processing device 5
A program necessary for the arithmetic processing of FIG. 6c is stored in advance, necessary values in the arithmetic processing process and arithmetic results are sequentially stored, and a target yaw rate map for calculating a target yaw rate is stored in advance. Here, as shown in FIG. 13, the target yaw rate map has a steering angle detection value θ _F of the steering angle sensor 54S on the X axis and a vehicle speed sensor 53 on the Y axis.
And a target yaw rate Y _O on the Z-axis, respectively, and a three-dimensional map that peaks when the steering angle detection value θ _S is 90 degrees and the vehicle speed detection value V is 60 km / h, for example. I have.

Next, the operation of the above embodiment will be described with a microcomputer.
Of the damping force control processing of the arithmetic processing unit 56c of the computer 56
FIG. 10 showing an example, FIG. 11 showing an example of a steering control process, and
FIG. 12 illustrates an example of the control gain setting process.
You. That is, the damping force control processing of FIG.
(For example, every 20 msec)
First, in step S1, the vehicle speed detection value V and the steering angle detection value θ
_SAnd each vertical acceleration detection value X_2i″ (I = FL, FR, RL, R
R), and then proceeds to step S2, where each phase is read.
Displacement detection value X_DiAnd then proceed to step S3
Then, the vertical acceleration detection value X read in step S1_2i″
Is integrated by, for example, low-pass filtering.
Body vertical speed X_2i′ Are calculated and these are stored in the storage device 56 d
Is temporarily stored in a predetermined storage area, and then the process proceeds to step S4.
And the relative displacement detection value X read in step S2._DiThe example
For example, by performing high-pass filter processing,
Speed X_Di′ Are calculated, and these are stored in a predetermined
After the temporary storage in the storage area, the process proceeds to step S5.

In step S5, step S3
And the vehicle vertical speed X calculated in S4 _2i'And relative velocity X
_Di'And control gain C_SCalculation of the following equation (1) based on
Coefficient C for performing skyhook control by performing_iTo
Calculate and update them in the specified storage area of the storage device 56d.
Remember. C_i= C_S・ X_2i'/ X_Di'(1) Next, the processing shifts to step S6, and the difference shown in FIG.
In the normal control processing, the front wheel side damping force control flag FF and the rear wheel side
Both damping force control flags FR are reset to "0".
And whether both flags FF and FR are both “0”
If the value has been reset to
And either flag FF or FR is set to "1".
If so, the process proceeds to step S7,
Wheel side damping force control flag FF is set to "1"
Control flag FF is set to "1".
If so, the process proceeds to step S8, where the rear wheel side damping is performed.
Whether the force control flag FR is set to "1"
It is determined that the control flag FR is set to "1".
Then, the process proceeds to step S9, where the respective attenuation coefficients C_FL~ C
_RRIs the maximum damping coefficient C_MAXAnd set this to the storage device 56
d is updated and stored in the predetermined storage area, and then the process proceeds to step S12.
The control is shifted and the control flag FR is reset to “0”.
Sometimes, the process proceeds to step S10, where the front-wheel-side damping coefficient C
_FLAnd C_FRIs the maximum damping coefficient C_MAXSet these to
Is updated and stored in a predetermined storage area of the storage device 56d.
The process moves to step S12.

On the other hand, the result of the determination in step S7 is
If the damping force control flag FF is not set to "1"
The rear wheel side damping force control flag FR is set to "1"
Is determined to have been made, the process proceeds to step S11,
Rear wheel damping coefficient C_RLAnd C _RRIs the maximum damping coefficient C
_MAXAnd these are stored in a predetermined storage area of the storage device 56d.
Then, the process proceeds to step S12.

In step S12, the above steps S5 and S5
S9, S10 or damping coefficient C _i calculated in S11 is equal to or less than the minimum damping force C _MIN of a preset variable damping force shock absorber 3i, C _i> C _MIN
, The process proceeds to step S13 to determine whether or not the vehicle body vertical speed X _2i ′ is positive. If X _2i ′> 0, the process proceeds to step S14 and proceeds to step S14.
5, S9, the damping coefficient C _i calculated in step S10 or S11 to set at the extension side, the control map corresponding to FIG. 8 theta
With reference to the region of _A through? _B1 moves from the calculated target step angle theta _T in step S15.

In step S15, the storage device 56d
Current step angle θ stored in _PAnd target step angle
θ_TIs calculated as a step control amount S.
While updating and storing in a predetermined storage area of the storage device 56d,
The target step angle θ_TIs the current step angle θ_PUpdate as
New storage is performed, and then the process proceeds to step S16, where the storage
Step control stored in a predetermined storage area of the storage 56d
Outputs the amount S to the motor drive circuit 59i and then interrupts the timer
The process ends and returns to the predetermined main program.

The result of the determination in step S13 is X _2i '.
<When 0, the process proceeds to step S15, the step S5, S9, S10 or S11 the damping coefficient C _i calculated as set in the compression in, theta _B2 through? _C of the control map corresponding to FIG. 8 Step angle θ
After calculating _T , the process proceeds to step S15. Further, when the determination result of step S12 is that C _i ≦ C _MIN , the process proceeds to step S18, and the target step angle θ _T is determined by referring to the region of θ _B1 to θ _B2 of the control map corresponding to FIG. After the calculation, the process proceeds to step S15.

The processing in FIG. 10 corresponds to the damping force control means. The steering control process of FIG. 11 is executed as a timer interrupt process every predetermined time (for example, 20 msec), similarly to the above-described damping force control process. First, in step S21, the vehicle speed detection value V of the vehicle speed sensor 53 and the steering angle sensor 54S the steering angle detection value theta _S, the yaw rate detected value Y of the yaw rate sensor 55
_D and the rear wheel steering angle detection value δ _rd of the rear wheel steering angle sensor 54R are read, and then the process _proceeds to step S22, in which the steering angle detection value θ _S is divided by the steering gear ratio N to obtain the front wheel steering angle δ _F (=
θ _S / N) is calculated.

Next, the routine proceeds to step S23, where the following equation (2) is calculated based on the detected vehicle speed V to calculate the steering angle ratio k of the front and rear wheels. k = {bL−mV ² (a / C _r )} / {aL−mV ² (a / C _f )} (2) Next, the process proceeds to step S24, where the vehicle speed detection value V and the steering angle detection value θ Based on _S , the target yaw rate Y _O is calculated with reference to the target yaw rate map of FIG. 13, and then the process proceeds to step S25, where the deviation between the target yaw rate Y _O and the yaw rate detection value Y _D read in step S21. ε (=
Y _O −Y _D ), and then proceeds to step S26 to calculate the yaw rate deviation differential value ε ′ by differentiating the yaw rate deviation ε by, for example, a high-pass filter process, and then proceeds to step S27 to obtain the following (3) ) is calculated rear wheel steering angle [delta] _r by performing the calculation of the equation.

Δ _r = k · δ _f + k _P · ε + k _D · ε ′ (3) where k _P is a yaw rate feedback control gain, and is a storage device in a control gain setting process of FIG. The value updated and stored in the predetermined storage area of 56d is read and used, and k _D is a preset fixed value control gain. Then, the process proceeds to step S28, the rear wheel steering angle [delta] _r
Deviation between the rear wheel steering angle detected value [delta] _rd and _{Δδ r (= δ r -δ rd} )
Calculates, when the difference value .DELTA..delta _r is zero, the servo valve 8
It is both a logic value "0" to the control signal CS _ra and CS _rb for 5, when a difference value .DELTA..delta _r is positive (Δδ _r> 0), the control signal CS _ra to the logical value "1", the control signal CS _rb
To logic value "0", when the difference value .DELTA..delta _r is negative (Δδ _r <0), the control signal CS _ra to the logical value "0", respectively set the control signal CS _rb to the logical value "1" Drive circuit 60
a, 60b, then terminates the timer interrupt process and returns to the predetermined main program.

The processing in FIG. 11 corresponds to the steering control means. Further, similarly to the above-described damping force control processing and steering control processing, the abnormality control processing of FIG. 12 is executed as a timer interruption processing every predetermined time (for example, 20 msec). First, in step S31, the front wheel side damping force variable shock absorber is executed. 3
FL, 3FR, rear shock absorber with variable damping force 3RL,
An abnormality diagnosis is performed to determine whether an abnormal state has occurred in each control system of the 3RR and the rear wheel auxiliary steering cylinder 79. This abnormality diagnosis reads, for example, the detection values of each sensor and diagnoses whether or not these are within a normal range, or the deviation between the control command value of each control system and the actual control value is within an appropriate range. Diagnosis of whether or not there is an abnormality in any of the control system of the front wheel side variable damping force shock absorber, the control system of the rear wheel side variable damping force shock absorber and the control system of the rear wheel auxiliary steering cylinder , The abnormality control flag A indicating that
FF, AFR and AFS are set to "1".

Then, the process shifts to step S32 to determine whether or not all of the abnormality control flags AFF, AFR and AFS are in a normal state in which they are reset to "0". Then, the control gain C _S for calculating the damping coefficient C _i for the skyhook control is set to the standard value C _SN , which is updated and stored in a predetermined storage area of the storage device 56d, and the front wheel side damping force control is performed. the yaw rate feedback control gain k _P is set to the standard control gain k _PN in reset and steering control to the flag FF and the rear wheel side damping force control flag FR "0", updated and stored into a predetermined storage area of the storage device 56d After that, the timer interrupt processing is terminated and the program returns to the predetermined main program, and one of the abnormality control flags AFF, AFR and AFS is set to “1”. When is, the step S34
Move to

In this step S34, it is determined whether or not a control flag AFS indicating an abnormality in the rear wheel steering system is set to "1". When this is set to "1", the flow proceeds to step S35. Then, the rear wheel control process of FIG. 11 is stopped, and then the process proceeds to step S36, where the front wheel side damping force control flag FF and the rear wheel side damping force control flag FR
The "0" than the standard value C _SN control gain C _S at reset and the damping force control to set to a large value C _SH, shifts which after updating stored in a predetermined storage area of the storage device 56d to step S37 Then, it is determined whether or not the control flag AFF indicating abnormality of the control system of the front wheel side damping force variable shock absorber is set to “1”. If the control flag AFF is reset to “0”, The process proceeds to S38 to determine whether or not the control flag AFR indicating the abnormality of the control system of the rear wheel side variable damping force shock absorber is set to "1". If the control flag AFR is set to "1", the process proceeds to step S38. S39 proceeds to, and reset to "0" to the front wheel side control flag FF, a rear-wheel side control flag FR is set to "1", and sets the control gain C _S to a high control gain C _SH After this is updated and stored in a predetermined storage area of the storage device, the timer interrupt process is terminated and the process returns to the predetermined main program.

On the other hand, when the result of the determination in step S37 is that the control flag AFF is set to "1", the flow proceeds to step S40, where the front wheel side control flag F
F is set to "1" and the rear wheel side control flag FR is set to "0".
At the same time, the control gain C _S is set to the high control gain C _SH , and this is updated and stored in the predetermined storage area of the storage device 56d, and then the process proceeds to step S41.

In step S41, the control flag AFR
Is set to “1”, and if the control flag AFR is set to “1”, it is determined that all control systems are in an abnormal state, and the process shifts to step S41a. And the front wheel side and rear wheel side control flags FF
And FR are both set to "1" and then the arithmetic processing unit 5
6c, the control flag AFR is set to "0".
, The timer interrupt process is terminated and the process returns to the predetermined main program.

If the result of the determination in step S34 is that the control flag AFS has been reset to "0", the flow shifts to step S42, where the control flag A
It is determined whether or not the FF is set to "1". If the control flag AFF is set to "1", the process proceeds to step S43 to set the front wheel side control flag FF to "1". , The rear wheel side control flag FR is reset to “0”, the control gain C _{S is set} to the high control gain C _SH , and the yaw rate feedback control gain k _P is set to the high control gain k _PH. After the update storage in the storage area, the process proceeds to step S44.

In step S44, the control flag AF
It is determined whether or not R is set to "1". If the control flag AFR is set to "1", the process proceeds to step S45, where the front wheel side and rear wheel side control flags F
And sets the F and FR respectively "1" to set the yaw rate feedback control gain k _P a high control gain k _PH, which terminates the timer interrupt processing to update stored in a predetermined storage area of the storage device 56d When the control flag AFR is reset to "0", the timer interrupt process is terminated and the process returns to the predetermined main program.

Further, when the result of the determination in step S42 is that the control flag AFF has been reset to "0", the flow shifts to step S46 to control the control flag AFR.
Is set to "1", and when it is set to "1", the process proceeds to step S47, where the front wheel side control flag FF is reset to "0", and the rear wheel side control is performed. The flag FR is set to “1”, the control gain C _S is set to the high control gain C _SH , the yaw rate control gain k _P is set to the high control gain k _PH , and these are updated and stored in a predetermined storage area of the storage device 56d. After that, the timer interrupt process is terminated and the process returns to the predetermined main program.

Therefore, if the control systems of the front wheel side variable damping force variable shock absorbers 3FL, 3FR, the rear wheel side variable damping force variable shock absorbers 3RL, 3RR, and the rear wheel steering control system are in a normal state, step When the process of S12 is performed, the process proceeds to Step S33 via Steps S31 and S32, the front wheel side and rear wheel side damping force control flags FF and FR are both reset to “0”, and the control gain C _{S is set.} Is set to the standard control gain C _SN and the yaw rate control gain k _P is also set to the standard control gain k _PN , and these are updated and stored in a predetermined storage area of the storage device 56d.

At this time, the vehicle travels on a flat good road at a constant speed.
In this state, the vertical movement of the vehicle body is almost
Because it does not move, it is output from each vertical acceleration sensor 51FL-51RR.
Forced vertical acceleration detection value X_2FL"~ X_2RR″ Is almost zero
Become. For this reason, the damping force control processing of FIG. 10 was executed.
When the vehicle body vertical speed calculated in step S3
X_2FL'~ X_2RR'Is also substantially zero, and is calculated in step S5.
Damping coefficient C_FL~ C_RRIs also substantially zero, front wheel side and rear
The wheel side damping force control flags FF and FR are both reset to “0”.
Are set, steps S6 to S12 are performed.
To step S18 through which the extension side and compression side
Decay coefficient C_nMINAnd C_{aM IN}Step angle θ_B1~ Θ_B2of
Set the step angle within the range to the target step angle θ_TSet as
And the step angles of the step motors 41FL to 41RR are
Target step angle θ _TIs driven to match. this
Therefore, the damping force variable shock absorber 3FL-3RR valve body
31 is set to the position B shown in FIG.
The damping coefficients C on the extension side and the compression side of the piston 8 are the minimum damping, respectively.
Coefficient C_nMINAnd C_aMINIs set to So this
In this state, vibration due to fine irregularities on the road surface is input to the wheels
However, this is the variable damping force shock absorber 3FL-3RR
Is absorbed by the vehicle and not transmitted to the vehicle body, ensuring a good ride.
Can be

On the other hand, when the steering control process of FIG. 11 is executed, the vehicle is in a straight running state, so that the detected steering angle θ
_{Since S} is zero and the target yaw rate Y _O calculated in step S25 is also zero, the rear wheel steering angle δ _r calculated in step S27 is also zero, so that the control signals CS _ra and CS _ra
rb both assume the logical value “0” and maintain the straight traveling state.

In this good road running state, for example,
When passing through a temporary step such as a difference,
When the vehicle does not move up and down due to
_2FL'~ X_2RR′ Remain zero, so that the minimum damping coefficient C
_aMINAnd C_nMINWheels ride on steps to maintain condition
Although it can absorb the pushing force when raised,
Riding on a relatively large step, absorbing the thrust
Otherwise, the vehicle will be displaced upward.
Therefore, the vehicle vertical speed X_2FL'~ X_2RR′ Is positive
Will increase. Thus, the vehicle vertical speed X
_2FL'~ X_2RR′ Increases in the positive direction, step S7
And the step angle θ in FIG._A~ Θ_B1Attenuation in the area
Target step angle θ according to coefficient C_TIs calculated, so
The damping force variable shock absorber 3FL ~ 3RR valve body 31
Switching control is performed as shown in FIG. As a result, step riding
Relative speed X by raising_DFL'~ X_DRR′ Is negative, ie the body
Side displacement speed X_2i′ To the wheel side displacement speed X_1i'But
When the piston 8 moves to the compression side at high speed, the compression
Small damping coefficient C_aMINVibration to the wheel side
Input can be absorbed, and from this state the step
As a result, the rising speed on the wheel side is
Relative speed X_DFL'~ X_DRR′ Is positive
As a result, the piston 8 moves to the extension side. At this time
Means that the damping coefficient C has a large value,
Demonstrate the damping effect, then stop the lift of the body
And body vertical speed X_2FL'~ X_2RR′ Becomes zero
As described above, the step motors 41FL to 41RR are
It is rotated counterclockwise to return to position B, thereby
The minimum damping coefficient C on both the compression side and the extension side_aMINAnd C_nMINTo
Control, and then when the vehicle begins to descend,
Body speed X_2FL'~ X _2RR′ Increases in the negative direction
As a result, the process moves from step S13 to step S14.
Then, referring to the control map of FIG._B2~ Θ
_CTarget step angle θ according to the damping coefficient C in the range of_TIs calculated
By ejecting, the valve element 31 rotates further counterclockwise.
Then, it is turned to the turning position shown in FIG. For this reason,
The vehicle descends and the relative speed X_DFL'~ X_DRR′ Is negative
And the piston 8 moves to the compression side, the damping force is
By increasing the size, a large vibration damping effect is exhibited.

Conversely, when the wheels pass through the step of descending forward, the relative speeds X _DFL ′ to X _DRR ′ increase in the forward direction due to the rebound of the wheels, but the vehicle body does not move up and down at this time. Body vertical speed X _2FL '~ X
_{Since 2RR} 'is zero, the damping coefficients of the damping force variable shock absorbers 3FL to 3RR are the minimum damping coefficients C _aMIN and C _{nM IN}
Maintaining, allowing the lowering of the wheels, then the vehicle starts to descend, the vehicle body vertical velocity X _2FL '~X _2RR' is increased in the negative direction, is the attenuation coefficient C is a large value, the step angle θ will _{be B2} through? _C target step angle theta _T ranging is calculated, since the valve body 31 is rotated to the position shown in FIG. 7, a large damping force against movement of the compression side of the piston 8 As a result, the valve body 31 is rotated clockwise as the vehicle vertical speeds X _2FL ′ to X _2RR ′ become smaller and the damping coefficient C becomes smaller. Return to the B side, and the vehicle vertical speed _X2FL '~
When X _2RR ′ becomes zero, the valve element 31 is at the position B, and has the minimum damping coefficients C _aMIN and C _nMIN . Thereafter, when the vehicle body starts rising by _swinging back, the vehicle body vertical speeds X _2FL ′ to X _2RR ′ increase in the positive direction, and the relative speeds X _DFL ′ to X _DRR ′ become the positive direction. is the target step angle theta _T as a step angle theta _a side with an increase in the calculation, by the valve body 31 is a position shown in FIG. 5 is rotated in the clockwise direction, the movement of the extension side of the piston 8 , A large damping force can be given to exert a vibration damping effect.

As described above, when the vehicle travels on a temporary step while traveling on a good road, a good vibration damping effect can be exerted by the skyhook control. also, by the target step angle theta _T positive vehicle body vertical velocity X _2FL '~X _2RR' (or negative) by the step angle theta _a side (or step angle theta _C side) is calculated, the vehicle body is raised When the relative speeds X _DFL 'to X _DRR ' are negative and the vehicle body descends and the relative speeds X _DFL 'to X _DRR ' are positive, the damping coefficient C is set to the minimum damping coefficient C.
_aMIN and _CnMIN , the vehicle body rises and the relative speeds X _DFL 'to X _DRR ' become positive, and the vehicle body descends and the relative speed X
_DFL 'to X _DRR' vertical velocity of the damping coefficient C when it is damping direction as the negative X _2FL 'to X _2RR' and relative velocity X
_By controlling to the optimal damping coefficient according to _DFL 'to _XDRR ',
Good ride comfort can be ensured.

Even when the vehicle is traveling on a rough road, the vehicle body rises and the relative speeds X _DFL 'to X
_DRR 'is negative and the body descends and the relative speed X _DFL ' ~ X
_{When DRR} 'is in the excitation direction where it is positive, the damping coefficient C is controlled to the minimum damping coefficients C _aMIN and C _nMIN , and conversely, the vehicle body rises and the relative speeds X _DFL ' to X _DRR 'become positive and the vehicle body becomes When the relative velocity X _DFL 'to X _DRR ' is lowered and the relative velocity X _DFL 'to X _DRR ' is negative, the damping coefficient C is _{adjusted according} to the vertical velocity X _2FL 'to X _2RR ' and the relative velocity X _DFL 'to X _DRR '. By controlling to an optimal damping coefficient, a good ride comfort can be secured.

When the steering wheel 76 is turned right (or left) from a straight running state on a good road to a turning state, the left outer wheel, which is a turning outer wheel, first sinks into the vehicle body and becomes the inner turning wheel side. When viewed from the rear wheel side where the right wheel floats up, a roll that falls to the left is generated.
As described above, when the roll is generated in the vehicle body, the vertical acceleration sensors 51FL and 51FL on the left wheel side (or the right wheel side) are correspondingly provided.
In RL (or 51FR and 51RR), the detected vehicle vertical acceleration values X _2FL ″ and X _2RL ″ increase in the negative direction from zero, and the vertical acceleration sensors 51FR and 51RR on the right wheel side (or left wheel side).
(Or 51FL and 51RL), the vehicle vertical acceleration detection value X
_2FR ″ and X _2RR ″ increase from zero in the positive direction, so that the vertical movement of the vehicle body can be suppressed in the same manner as described above, and when the rear wheel steering process of FIG. 11 is started, step S27 Since the yaw rate feedback control gain k _P of the yaw rate feedback term of the second term on the right side of the above equation (3) is set to the standard control gain k _PN , steering stability can be secured without giving a sense of incongruity.

By the way, when an abnormality occurs in the rear wheel steering system during the running of the vehicle, when the processing of FIG. 12 is executed, the processing shifts from step S32 to step S35 via step S34, whereby FIG. Is stopped, the front two-wheel steering state is fixed, and then step S
At 36, the front wheel and rear wheel side control flags FF and FR are both reset to “0”, and the control gain C _S is set to the high control gain C _SH . This is updated and stored.
When the control system of the damping force variable shock absorbers 3FL to 3RR is normal, the timer interrupt processing is terminated through steps S37 and S38, and the set value of step S36 is maintained. When the processing is executed, the damping force of each of the damping force variable shock absorbers 3FL to 3RR becomes larger than the control gain C compared to the normal state described above.
_S is controlled to the high damping force side by the amount increased from the standard control gain _CSN to the high control gain _CSH , and a reduction in steering stability due to suspension of rear wheel steering control can be compensated. A sudden change in comfort and steering stability can be suppressed.

If the rear wheel steering system is in an abnormal state and one of the control systems of the front wheel side and rear wheel side variable damping force shock absorbers is in an abnormal state, the process proceeds to step S39 or step S40. Then, since the damping force control flag FF or FR of the abnormal control system is set to "1", when the damping force control processing of FIG. The absorber is controlled to the maximum damping force state, and the damping force variable shock absorber of the remaining normal control system is controlled to the high damping force side, and the control state emphasizes steering stability rather than ride comfort, A sudden change in stability can be suppressed. At this time, since both the left and right variable damping force variable shock absorbers of the abnormal control system are controlled to the high damping force state, only the control system of the abnormal variable damping force variable shock absorber is controlled to the high damping force state. As in the case, it is possible to suppress a feeling of instability due to a change in the left and right wheel loads, thereby ensuring steering stability.

Further, when all the control systems are in an abnormal state, the process shifts to step S41a to set all the damping force variable shock absorbers 3FL to 3RR to the maximum damping force state and then stop the control of the arithmetic processing unit 56c. It is possible to suppress a sudden change in steering stability. When the rear wheel steering system is normal and one of the front wheel side and rear wheel side damping force control systems is abnormal, when the process of FIG. 12 is executed, the process proceeds from step S34 to step S42. Then, the process proceeds to step S43 or step S47 to control the abnormal variable damping force shock absorber of the abnormal damping force control system to the maximum damping force state, and to set the normal variable damping force control system damping force variable shock absorber to the high damping force side. And the yaw rate feedback control gain k _P of the rear wheel steering system is changed to the high control gain k _PH . Therefore, when the process of FIG. 11 is executed, the response of the rear wheel steering is improved, and the damping is improved. A reduction in steering stability due to an abnormality in the control system of the variable force shock absorber can be compensated for by the rear wheel steering control system, and a sudden change in steering stability can be suppressed.

In the above embodiment, the case where the damping force variable shock absorbers are controlled to the maximum damping force state when the control system of the damping force variable shock absorbers 3FL to 3RR is abnormal has been described.
Drive motor 4 in case an abnormality occurs in
It is preferable to insert a return spring so that the valve element 31 automatically returns to the high damping force position when the driving force of 1FL to 41RR becomes zero.

Further, in the above embodiment, the case where the valve element 31 for controlling the damping force of the variable damping force shock absorbers 3FL to 3RR is formed as a rotary type has been described.
The present invention is not limited to this, and may be configured in a spool shape to form different flow paths on the compression side and the expansion side. In this case, a pinion is attached to the rotation shaft 41a of the step motors 41FL to 41RR. The sliding position of the valve body 31 may be controlled by connecting a rack that meshes with the pinion to the connecting rod 42 or by applying an electromagnetic solenoid, instead of changing the damping force continuously. It is also possible to apply a variable damping force shock absorber that can switch the damping force in a plurality of stages.

In the above embodiment, the rear wheel auxiliary steering cylinder 79 is provided with a closed sensor type servo valve 85.
However, the present invention is not limited to this, but is applicable to an open center type servo valve, and the piston rod 79a of the four-wheel drive 79 is returned to the neutral position accordingly. The control may be performed by interposing a spring.

Further, in the above embodiment, the case where the steering stability is ensured by the rear wheel steering system when the control system of the variable damping force shock absorber is abnormal has been described. However, the present invention is not limited to this. In a vehicle equipped with the device, the drive distribution on the front wheel side may be increased. Further, in the above embodiment,
The case where the yaw rate feedback control of the above-described equation (3) is performed in the rear wheel steering control is described.

Furthermore, in the above-described embodiment, the case where the control is performed by applying the microcomputer 56 has been described. However, the present invention is not limited to this, and the integration for integrating the outputs of the zero-cross detector and the vertical acceleration sensor 51i. An electronic circuit such as a device, a differentiating circuit for differentiating the output of the stroke sensor 52i, and a function generator may be combined.

In the above embodiment, the case where the potentiometer is used as the stroke sensor has been described. However, the present invention is not limited to this. The ultrasonic distance sensor for detecting the relative distance between the vehicle body and the road surface, the detection coil Any relative displacement detection means such as a displacement sensor that detects displacement by impedance change or inductance change using the above method can be applied.

Further, in the above embodiment, the vertical acceleration sensors 51FL to 51FL are located at the respective wheels 1FL to 1RR of the vehicle body 2.
Although the case where the RR is provided has been described, any one of the vertical acceleration sensors may be omitted, and the vertical acceleration at the omitted position may be estimated from the values of the other vertical acceleration sensors. Furthermore, in the above embodiment, the case where the step motors 41FL to 41RR are controlled by open loop has been described. However, the present invention is not limited to this, and the rotation angle of the step motors is detected by an encoder or the like, and this is fed back to perform closed loop control. You may make it.

[0063]

As explained above, according to the first aspect of the present invention,
According to the vehicle characteristic control device for a wheel steering vehicle, the front wheel side and the rear
When one of the wheel side damping force control systems becomes abnormal
In addition, the left and right damping force variable shock
By fixing the bushover to the high damping force state, the left and right
It is possible to secure steering stability by suppressing changes in wheel load.
The effect that can be obtained is obtained.

According to the vehicle characteristic control device for a four-wheel steering vehicle according to the second aspect, an abnormality occurs in the four-wheel steering control system.
The vehicle returns to the two-wheel steering state and the damping force
Steerability by controlling the variable shock absorber to the high damping force side
The effect is that the qualitative characteristics can be improved and sudden changes in vehicle characteristics can be suppressed.
can get.

[0065]

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a basic configuration of the present invention.

FIG. 2 is a schematic configuration diagram showing one embodiment of the present invention.

FIG. 3 is a partially sectional front view showing an example of a variable damping force shock absorber.

FIG. 4 is an enlarged sectional view showing a damping force adjusting mechanism in a maximum damping force state when the vehicle body is lifted.

FIGS. 5A and 5B are enlarged cross-sectional views showing a damping force adjusting mechanism in an intermediate damping force state when the vehicle body is lifted, wherein FIG. 5A shows a hydraulic oil path on the extension side and FIG.

FIGS. 6A and 6B are enlarged cross-sectional views showing a damping force adjustment mechanism when the vehicle body does not fluctuate, wherein FIG. 6A shows a hydraulic oil path on the extension side and FIG.

FIGS. 7A and 7B are enlarged cross-sectional views showing a damping force adjusting mechanism in a state of maximum damping force when the vehicle body descends, wherein FIG. 7A shows a hydraulic oil path on the extension side and FIG.

FIG. 8 is an explanatory diagram showing a damping force characteristic with respect to a step angle of a variable damping force shock absorber.

FIG. 9 is a block diagram illustrating an example of a controller.

FIG. 10 is a flowchart illustrating an example of a damping force control processing procedure of a controller.

FIG. 11 is a flowchart illustrating an example of a steering control processing procedure of a controller.

FIG. 12 is a flowchart illustrating an example of a control gain setting processing procedure of the controller.

FIG. 13 is a characteristic diagram showing a target yaw rate map showing a relationship between a detected steering angle, a detected vehicle speed, and a target yaw rate.

[Explanation of symbols]

 1FL to 1RR Wheel 2 Body 3FL to 3RR Damping force variable shock absorber 4 Controller T1 to T3 Expansion side flow path C1 to C4 Pressure side flow path 41FL to 41RR Step motor 51FL to 51RR Vertical acceleration sensor 52FL to 52RR Stroke sensor 53 Vehicle speed sensor 54S Steering Angle sensor 54R Rear wheel steering angle sensor 55 Yaw rate sensor 56 Microcomputer 59FL-59RR Motor drive circuit 76 Steering wheel 79 Rear wheel auxiliary steering cylinder 85 Servo valve

Claims (2)

(57) [Claims] 1. A suspension having a variable damping force shock absorber, an auxiliary steering device for auxiliary steering of at least a rear wheel, and damping force control means for controlling a damping force of the variable damping force shock absorber in accordance with a vertical movement of a vehicle body. When,
A vehicle characteristic control device for a four-wheel steering vehicle including a steering control means for controlling the auxiliary steering device in accordance with a steering angle or the like, wherein an abnormal state of a control system including a front wheel side damping force variable shock absorber is detected. 1 abnormal state detecting means, second abnormal state detecting means for detecting an abnormal state of a control system including a rear-wheel-side variable damping force shock absorber, and abnormal state of a control system including a rear-wheel auxiliary steering device. Third abnormal state detecting means for detecting, the first abnormal state detecting means,
When an abnormality is detected in any of the abnormal state detecting means and the third abnormal state detecting means comprises an abnormality control processing means for compensating the vehicle characteristics in the rest of the control system, the abnormality control process
The means comprises a first abnormal state detecting means and a second abnormal state detecting means.
When an abnormality is detected by any of the
Variable shock absorber of the control system with high damping force
And the yaw rate control
Of the motor to a high control gain.
A vehicle characteristic control device for a four-wheel steering vehicle, characterized in that: 2. A shock absorber having a variable damping force.
Suspension and at least rear wheel assist steering
Steering device and damping of variable damping force shock absorber
Damping force control means for controlling the force according to the vertical movement of the vehicle body,
Steering control for controlling the auxiliary steering device according to a steering angle or the like
Characteristic control device for a four-wheel steering vehicle comprising:
Control including variable front wheel shock absorber
First abnormal state detecting means for detecting an abnormal state of the system;
Differences in the control system including the variable damping force shock absorber on the wheel side
Second abnormal state detecting means for detecting a normal state;
A third abnormality detecting an abnormal state of the control system including the auxiliary steering device.
A normal state detecting means, the first abnormal state detecting means,
Any one of the abnormal state detecting means and the third abnormal state detecting means
When the abnormality is detected by the
Abnormality control processing means for compensating, and the abnormality control processing
Means for detecting an abnormality by the third abnormal state detecting means
At the same time, the control of the steering
And rear wheel side damping force damping force of variable shock absorber
Japanese that is configured to control the high damping force side
A vehicle characteristic control device for a four-wheel steering vehicle.