JP3180581B2 - Suspension 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 suspension control device for predictively controlling an actuator interposed between a wheel to be controlled and a vehicle body based on detected road surface information.

[0002]

2. Description of the Related Art As a conventional suspension control device, there is one described in, for example, JP-A-61-135811 and JP-A-61-166715. Suspension control device described in JP-A-61-135811 (hereinafter referred to as a first conventional example)
Is provided with a wheel that is rotationally driven along a road surface, and a spindle mechanism that supports the wheel and the vehicle body at a predetermined stroke. A detection unit which is disposed in front of the wheel to be controlled and which is constituted by a non-contact type sensor for detecting the unevenness of the road surface; And a valve drive mechanism for exciting an electromagnetic valve so as to inject or discharge hydraulic pressure to or from the spindle mechanism according to the command.

A suspension control device described in Japanese Patent Application Laid-Open No. Sho 61-166715 (hereinafter referred to as a second conventional example) is a suspension control device in which a rear wheel is a wheel to be controlled. Front wheel acceleration detecting means for detecting acceleration in a vertical direction at least to the road surface applied to the front wheel; determining means for determining whether or not the acceleration detected by the front wheel acceleration detecting means is outside a predetermined range; When the acceleration is determined to be out of the predetermined range, a rear wheel suspension characteristic changing means for changing a rear wheel suspension characteristic, for example, an air spring constant or the like, is provided.

[0004]

However, in the above-described conventional suspension control apparatus, the first conventional example uses a non-contact type sensor, such as an ultrasonic sensor or an optical sensor, to drive the target wheel. Although the suspension control is performed by obtaining the road surface information in front, non-contact sensors such as the ultrasonic sensor and the optical sensor are expensive, which leads to an increase in the cost of the control device.

Further, the above-mentioned non-contact type sensor has dust, mud,
Errors tend to occur due to water droplets, snow pools, and the like, which may cause inaccurate suspension control on the target wheel side. As a result, the ride comfort may not be improved to the intended ride comfort, or conversely, may cause extra vibration in some cases. In the second conventional example,
The non-contact type sensor as described above is used because it detects the unevenness of the road surface at the front wheel position by detecting the unsprung motion of the front wheel and controls the suspension of the rear wheel based on the detected value. I haven't. However, when this control is adopted, only the vibration on the rear wheel side is reduced, and the vibration on the front wheel side remains unchanged. For this reason, the riding comfort in the back seat is improved, but the riding comfort in the front seat is not as improved as in the back seat. Further, in this control, the pitching behavior of the vehicle is increased, and the occupant may feel discomfort.

At this time, it is conceivable to use the conventional control means as described above to detect, for example, unsprung motion of the front wheel and to execute suspension control of the front wheel itself according to the detected value. However, there is a problem in that the operation time is delayed and the response of the actuator system is delayed. That is, when the rear wheel side is controlled by the road surface information detected on the front wheel side, the delay of the control system is compensated by setting the information delay time shorter than the wheel base passage time of the target road surface. can do. However, in the case of controlling the front wheels on the basis of the road surface information of the front wheels and controlling the rear wheels on the basis of the road surface information of the rear wheels, the delay of the control system cannot be compensated. For this reason, the phase lag of the control force particularly in a high-frequency range becomes large, which results in that the vibration cannot be sufficiently suppressed or unnecessary vibration is caused.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to effectively control a suspension on a wheel based on road surface information on the wheel.

[0008]

[0009]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The suspension control device according to claim 1 of the present invention is an actuator that is interposed between a wheel and a vehicle body and generates a control force capable of controlling a vertical stroke between the wheel and the vehicle body by a control signal. A unsprung motion estimating means for estimating a vibration input transmitted from the road surface to the suspension; Transmission force calculating means for calculating each vibration input, and a vibration input value obtained by subjecting a vibration input value for a spring element to a low-pass filter processing based on each calculated value of the transmission force calculation means, and a vibration for the damping element. Control means for supplying to the actuator a control signal for canceling a vibration input obtained as a sum with an input value.

A suspension control device according to a second aspect of the present invention is provided between a wheel and a vehicle body and has a control force capable of controlling a vertical stroke between the wheel and the vehicle body by a control signal. The generated actuator, unsprung motion estimating means for estimating a vibration input transmitted from the road surface to the suspension, and a vehicle body from unsprung through a spring element and a damping element of the suspension based on the estimated value of the unsprung motion estimating means. A transmission force calculating means for calculating each vibration input transmitted to the actuator, and a control means for supplying a control force for canceling the vibration input to the actuator based on each vibration input value calculated by the transmission force calculation means. The control means includes a control unit that calculates a low value of the vibration input value of the spring element by multiplying the vibration input value of the damping element by a control gain smaller than 1. It is characterized by supplying a control signal to cancel the vibration input value obtained as a sum of the vibration input value after the scan filter.

Further, with respect to the configuration described in 請 Motomeko 2, The invention described in claim 3, the control gain is changed according to the control gain for the vibration input of the damping element content in the vibration state of the vehicle It is characterized in that variable means is provided. A suspension control device according to claim 4.
Is mounted between the wheels and the vehicle body and controlled by control signals.
A control force capable of controlling the vertical stroke between the wheel and the vehicle body
Actuator generated, from road surface to suspension
Unsprung motion estimating means for estimating the transmitted vibration input;
Based on the estimated value of the unsprung motion estimating means, the suspension
Transmitted from the unsprung part to the vehicle body through the spring element and damping element
Transmission force calculating means for calculating each vibration input to be reached;
Based on each calculation value of the attainment force calculation means,
After multiplying the dynamic input value by a control gain smaller than 1.
As the sum of the vibration input value and the vibration input value for the above spring element
The control signal for canceling the obtained vibration input is
And control means for supplying the data to the damping element.
The control gain for the vibration input depends on the vibration state of the vehicle.
Characterized by the provision of variable control gain means for changing
I have. Further, in contrast to the configuration described in claim 1 or claim 2 , the invention described in claim 5 provides a cutoff frequency change that changes the cutoff frequency of the low-pass filter processing according to the vibration state of the vehicle. It is characterized in that means are provided.

[0012]

According to the present invention, a vibration input transmitted from a road surface to a suspension via a wheel is estimated as road surface information on a target wheel, and a vibration input transmitted to a vehicle body via a suspension is calculated from the estimated value. The control means calculates a control force for canceling the actual vibration input transmitted to the vehicle body based on the calculated vibration input, and reduces the vibration input to the vehicle body by generating the calculated control force by the actuator. To control.

At this time, since the suspension of the target wheel is controlled based on the road surface information of the target wheel, the influence of the calculation time of the control means and the response delay of the actuator as described above becomes a problem. . In order to confirm the effect of the response delay, the actuator is driven by the hydraulic system and the cutoff frequency 6
It was subjected to a simulation based on the assumption that with a temporary delay in the H _Z, to give the results shown in FIG. 10.

FIG. 10 is a diagram showing a transmission characteristic of a vertical change of the vehicle body with respect to a road surface change. A dotted line indicates a case where the suspension control is not performed, and a solid line indicates a case where the suspension control is performed. Thus, the control still having the temporary delay, 5～6H _Z or more frequency bands characteristic than "no control" in (under resonance frequency range spring) is deteriorated and also, the frequency band of 1～2H _Z vicinity It can be seen that the characteristics are improved in the (spring-spring resonance frequency range).

[0015] However, high-frequency vibration region for generally high human sensitivity, without reducing the effect of the area of 5H _Z following frequency bands, it is necessary to prevent an adverse effect on 6H _Z or more frequency bands. Therefore, of the vibration inputs estimated to be transmitted to the vehicle body via the suspension, the vibration suppression control of only the vibration input of the spring element is performed, and the vibration suppression control of only the vibration input of the damping element is performed. As a result, the results indicated by broken lines and alternate long and short dash lines in FIG. 10 were obtained.

[0016] As will now be seen, in order not to drop the control effect in 5H _Z following areas counteracts the vibration input of the spring element content is essential, the damping element to remove only the adverse effects of a high-frequency region It is understood that only the control force for the minute needs to be weakened. This is a natural conclusion considering that the spring component is the dominant force in the low frequency range and the damping component is the dominant force in the high frequency range.

[0017]

[0018] The description of the operation of the invention described in 請 Motomeko 1. When the simulation was performed by changing the control gain for the vibration input value of the estimated damping element between 0 and 1, the result as shown in FIG. 12 was obtained.

[0019] As can be seen from FIG. 12, as the control gain approaches 0 from 1, it is possible to reduce the adverse effects of at 6~10H _Z (unsprung resonance frequency region), 1~5H _Z (sprung The control effect in the resonance frequency range) is reduced. However, compared to the case where the suspension control as shown in FIG. 11 is not performed, the control effect near the sprung resonance region is sufficiently maintained even when the control gain becomes zero, and the control effect in the high frequency region is reduced. The adverse effects can be almost eliminated.

Therefore, for example, if the vibration level in the sprung resonance frequency region is large, the control gain is made closer to 1, and the control gain is changed according to the vibration state of the vehicle, so that fine suspension control is performed. . Next, the operation of the invention described in claim 2 will be described.
The basic control according to the present invention is the same as that of the first aspect of the present invention. As the road surface information on the target wheel, a vibration input transmitted from the road surface to the suspension via the wheel is estimated, and the suspension is determined from the estimated value. The control unit calculates a vibration input transmitted to the vehicle body through the control unit, calculates a control force for canceling an actual vibration input transmitted to the vehicle body based on the calculated vibration input, and calculates the calculated control force. The vibration generated by the actuator is controlled to reduce the vibration input to the vehicle body.

At this time, based on the simulation result shown in FIG. 10, control is performed so that both the vibration input to the vehicle body via the estimated spring element and the vibration input to the vehicle body via the damping element are canceled. Rather than controlling to cancel only the vibration input on the damping element side,
It can be seen that the control characteristic is improved for the vibration component in the frequency range above the vicinity of 2.2H _Z. That is, 2.
For damping of the vehicle body in the frequency range above the vicinity 2H _Z, it is understood that the control for the vibration input of the estimated the spring element side is adversely affected reversed.

In view of the above, according to the second aspect of the present invention, a low-pass filter process is performed on the estimated vibration input input to the vehicle body from the spring element, so that high-frequency components causing the adverse effect are cut off. Further, the adverse effect in the high frequency region due to the response delay of the control system is suppressed without lowering the control effect in the sprung resonance frequency region. Next, the operation of the invention described in claim 3 will be described.

According to the second aspect of the present invention, the low-pass filter processing suppresses the adverse effect in the high frequency region due to the response delay of the control system. At this time, the cut-off frequency of the low-pass filter processing is reduced. In order to confirm the effect due to the change in, the simulation was performed by changing the cutoff frequency of the low-pass filter, and the result shown in FIG. 14 was obtained.

From these results, when the cutoff frequency is high (7 Hz), the effect of reducing the vibration of 1-2 Hz is large,
When the cut-off frequency is low (3 Hz),
It can be seen that the 7 Hz vibration reduction effect is large. In view of this, in the invention according to claim 3 , the cutoff frequency of the low-pass filter processing is changed according to the vehicle vibration state, for example, when the vibration in the frequency range of 1 to 2 Hz is large, the cutoff frequency is increased. As a result, fine suspension control is performed. Next, according to claim 4
The operation of the invention will be described. As mentioned above, 5Hz or less
In order to keep the control effect in the lower area, the spring element
Canceling the vibration input of
To eliminate only the adverse effects in the
It turns out that you only need to weaken your power. This is a low frequency
The force is dominated by the spring component in the high frequency range and the damping component in the high frequency
Is a natural conclusion. In view of this,
According to the fourth aspect of the present invention, the estimated attenuation component
Vibration input value was corrected to a value smaller than the estimated value
Later, to find the control force generated by the actuator
To reduce the adverse effects of high-frequency control,
Suspension at the wheel position based on road surface information at the wheel position
And it is possible to obtain a predetermined vibration suppression effect
Become. For example, set the control gain to 0.5, which is smaller than 1.
Fig. 11 shows the results of the simulation.
The above results were obtained in a high frequency range of 6 Hz or more.
It can be seen that the adverse effect of the control is reduced. Ma
In addition, changing the control gain according to the vehicle vibration state
Thus, fine suspension control is performed.

Next, the operation of the invention described in claim 5 will be described. The invention described in claim 5 obtains an effect obtained by combining the operation of the above-described invention of claim 2 and the operation of the invention of claim 4 . For example, when a simulation is performed with a control gain of 0.75 and a cut-off frequency of the low-pass filter processing of 3.0 Hz (when vibration reduction around 3 to 7 Hz is considered), a result as shown in FIG. 15 is obtained. And 8H while maintaining a sufficient control effect near the sprung resonance frequency as compared with “no control”.
It can be seen that the vibration peak near z is greatly reduced.

[0026]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention,
In the drawing, 10 indicates a vehicle body side member, 11FL to 11RR indicate front left to rear right wheels, and 12 indicates a suspension control device.

The suspension control device 12 includes a vehicle body-side member 10 and wheels 11FL to 11RR of wheels 11FL to 11RR.
Hydraulic cylinders 18FL to 18RR as actuators respectively interposed between the RR side member 14, pressure control valves 20FL to 20RR for individually adjusting the operating pressures of the hydraulic cylinders 18FL to 18RR, and pressure control valves 20FL Supply hydraulic fluid at a predetermined pressure to ~ 20RR
1S and the pressure control valves 20FL-2
A hydraulic source 22 for collecting return oil from the ORR through a return pipe 21R;
Accumulators 24F and 24R for accumulating pressure inserted in the supply pressure side pipe 21S between L to 20RR, and each wheel 11FL to
Stroke sensors 27FL to 27RR arranged in parallel with the hydraulic cylinders 18FL to 18RR of the 11RR and detecting relative displacement between the wheels 11FL to 11RR and the vehicle body;
Vertical acceleration sensors 28FL to 28RR for individually detecting the vertical acceleration of the vehicle body at positions corresponding to the wheels 11FL to 11RR, respectively, and vertical acceleration detection values Z _{GFL to} Z _GRR of the vertical acceleration sensors 28FL to 28RR. Each pressure control valve 20FL-2
0RR is actively controlled, and each sensor 27FL-27 is controlled.
And each wheel 11 based on the detected values of
Wheels 11F corresponding to the motion state of FL to 11RR
A controller 30 for individually preview controlling the output pressures of the pressure control valves 20FL to 20RR of L to 11RR.

Each of the hydraulic cylinders 18FL to 18RR has a cylinder tube 18a, and a lower pressure chamber LP is formed in the cylinder tube 18a by a piston 18c having an axial through hole.
A thrust is generated according to the pressure receiving area difference between the upper and lower surfaces of the piston 18c and the internal pressure. Then, the lower end of the cylinder tube 18a is attached to the wheel side member 14, and the piston rod 18
The upper end of b is attached to the vehicle body side member 10. Each of the pressure chambers LP is connected to an output port of each of the pressure control valves 20FL to 20RR via a hydraulic pipe 38. The pressure chambers L of the hydraulic cylinders 18FL to 18RR
Each of the Ps is connected via a throttle valve 32 to an accumulator 34 for absorbing unsprung vibration. A coil spring 36 having a relatively low spring constant and supporting a static load of the vehicle body is disposed between the upper and lower portions of each of the hydraulic cylinders 18FL to 18RR.

Each of the pressure control valves 20FL to 20RR includes a cylindrical valve housing having a spool slidably mounted therein and a proportional solenoid integrally provided with the cylindrical valve housing. It is composed of a port proportional electromagnetic pressure reducing valve (for example, one described in Japanese Patent Application Laid-Open No. 64-74111). Then, by adjusting the command current i (command value) supplied to the excitation coil of the proportional solenoid, the moving distance of the poppet housed in the valve housing,
That is, the position of the spool is controlled, and the hydraulic power source 22 is supplied through the supply port and the output port or the output port and the return port.
The hydraulic oil flowing between the hydraulic cylinders 18FL to 18RR can be controlled.

Here, the command current i (: i _{FL to} i _RR ) applied to the exciting coil and the pressure control valve 20FL (to 20R)
The relationship with the control pressure P output from the output port of R) is
As shown in FIG. 3, the minimum current value i _{MIN in} consideration of noise
Minimum control pressure P _MIN, and the linearly control pressure P increases in proportion to increasing the current value i from the state current value i, setting the hydraulic pressure source 22 when the maximum current value i _MAX when the highest control pressure P _MAX corresponding to line pressure. In FIG. 2, i _N is a neutral command current, and P _N is a neutral control pressure.

As shown in FIG. 4, each of the stroke sensors 27FL to 27RR has a neutral voltage of zero when the vehicle height coincides with a predetermined target vehicle height. When the vehicle height becomes higher than the target vehicle height, as shown in FIG. When the vehicle height is lower than the target vehicle height, the stroke detection values S _{FL to} S _RR are output as negative voltages corresponding to the deviation.

Vertical acceleration sensors 28FL-28RR
As shown in FIG. 5, when the vertical acceleration is zero, zero voltage is detected, when an upward acceleration is detected, a positive analog voltage corresponding to the acceleration value is detected, and a downward acceleration is detected. When it does, it is configured to output the vertical acceleration detection values Z _{GFL to} Z _GRR consisting of a negative analog voltage corresponding to the acceleration.

As shown in FIG. 2, the controller 30 detects stroke detection values S _FL -S _RR input from each of the stroke sensors 27FL-27RR and vehicle body up / down output from each of the vertical acceleration sensors 28FL-28RR. An A / D converter 43 that changes the detected direction acceleration values Z _{GFL to} Z _{GR R} into digital values, and an A / D converter 43
Microcomputer 44 to which the / D conversion output is input
And the pressure command values P _{FL to} P _RR output from the microcomputer 44 are supplied via the D / A converter 45 and are converted into drive currents i _{FL to} i _RR for the pressure control valves 20FL to 20RR. For example, it includes drive circuits 46FL to 46RR configured by floating type constant voltage circuits.

When the ignition key switch is turned on, the controller 30 is turned on and the initialization is performed. The microcomputer 44 includes at least an interface circuit 44a,
It has an arithmetic processing unit 44b and a storage unit 44c. The conversion output of the A / D converter 43 is input to the interface circuit 44a, and the pressure command value P _FL for each of the pressure control valves 20FL to 20RR from the arithmetic processing unit 44b is input.
ＰP _RR is output to the D / A converter 45.

Further, the arithmetic processing unit 44b performs processing to be described later.
And a predetermined sampling time T_S(Eg 2
0 msec), every corresponding wheel 11FL-11RR
Troke detection value S_FL~ S_RRAnd vehicle body vertical acceleration detection
Value Z_GFL~ Z_GRRAre read, and each wheel 11FL-11R
From road surface at R position to suspension via wheels
The transmitted unsprung input speed is (dX_FL/ Dt)-(d
X_RR/ Dt), and based on the estimated value, each wheel 1
Hydraulic syringe as 1FL-11RR actuator
Foreseeing control force U generated in the motors 18FL to 18RR_PFL~ U
_PRRAnd acceleration sensors 28FL-28R
Vertical acceleration detection value Z of each vehicle body from R _GFL~ Z_GRRTo
Integrated vehicle vertical velocity Z_VFL~ Z_VRRBased on sky
Active control system for each wheel with hook damper function
Control force is calculated, and the value obtained by adding both control forces is
Pressure command value P for force control valves 20FL to 20RR_FL~
P _RRTo the D / A converter 45.

The storage device 44c stores a program necessary for the arithmetic processing of the arithmetic processing device 44b in advance, and sequentially stores the arithmetic results required in the arithmetic process of the arithmetic processing device 44b. Next, the operation of the above embodiment will be described with reference to the flowchart of FIG.

The processing in FIG. 7 is performed for a predetermined sampling time T
_This is executed as a timer interrupt process every _S (for example, 20 msec). First, in step S1, each wheel 11FL-1FL
The stroke detection values S _{FL to} S _RR and the vehicle body vertical acceleration detection values Z _{GFL to} Z _GRR corresponding to 1RR are read, and the process _proceeds to step S2.

In step S2, each of the wheels 11F
Based on stroke detection values S _FL -S _RR and vehicle body vertical acceleration detection values Z _GFL -Z _GRR corresponding to L-11RR, wheels 11FL-11R that accurately follow the road surface shape.
The differential value of the road surface change of R, that is, the unsprung input speed (dX _FL /
dt) to (dX _RR / dt), and the process proceeds to step S3.

The process of estimating the unsprung input speed is performed by differentiating the stroke detection values S _{FL to} S _RR to obtain the stroke speed (d
To calculate S _FL / dt) ~ a (dS _RR / dt), the vehicle body vertical acceleration detected value Z _GFL to Z _GRR integrated differential value of the sprung displacement of _{(dY FL / dt) ~ (} dY RR / dt ) Is calculated. Next, by adding the stroke speed and the differential value of the sprung displacement, the differential value (dX _FL / dt) to (dX _RR / d) of the road surface displacement of each wheel that accurately follows the road surface shape.
t) is output.

That is, the stroke sensors 27FL to 27R
Since the stroke detection values S _{FL to} S _RR output from R represent the relative displacement between the unsprung and the unsprung, as represented by the following equations (1) to (4), the respective wheels 11FL to 11R
From the unsprung displacement X _{FL to} X _{RR of the} R, the sprung displacement Y _{FL of the} vehicle body
Y _RR is subtracted from each other. S _FL = X _FL -Y _FL (1) S _FR = X _FR -Y _FR (2) S _RL = X _RL -Y _RL (3) S _RR = X _RR -Y _RR (4) Accordingly, the stroke speed obtained by differentiating the stroke detection values S _{FL to} S _RR is a value obtained by subtracting the differential value of the sprung displacement from the differential value of the unsprung displacement. By adding the differential value of the sprung displacement obtained by adding Z _{GFL to} Z _GRR to the differential value of the sprung displacement, the differential value of the true road surface displacement (dX _FL / d) that offsets the differential value of the sprung displacement and follows the road surface displacement
t) to (dX _RR / dt).

In step S3, each of the calculated wheels 1
The unsprung input speeds of 1FL to 11RR are integrated to calculate unsprung displacements (road surface displacements) X _{FL to} X _RR. Based on the unsprung input speed and unsprung displacement, the following formula (5) is used to calculate (1)
2) Perform the calculations of the equations. Thereby, each wheel 1
At positions 1FL to 11RR, spring-side vibration inputs Fs _{FL to} Fs _RR transmitted to the vehicle body via a coil spring 36 or the like, which is a spring element of the suspension, and to a vehicle body via shock absorbers 18FL to 18RR which are damping elements. The transmitted damping-side vibration inputs Fd _{FL to} Fd _RR are calculated.

Fs _FL = K _FL · X _FL (5) Fs _FR = K _FR · X _FR (6) Fs _RL = K _RL · X _RL (7) Fs _RR = K _RR · X _RR · · · (8) Fd _FL = C _FL · (dX _FL / dt) · · · (9) Fd _FR = C _FR · (dX _FR / dt) · · · (10) Fd _RL = C _RL (DX _RL / dt) (11) Fd _RR = C _RR (dX _RR / dt) (12) Here, C _FL , C _FR , C _RL , and C _RR are each wheel. Represents the damping coefficients of the shock absorbers 18FL to 18RR corresponding to, and K _FL , K _FR , K _RL , and K _RR represent one wheel for each wheel.
It shows the spring constant of the suspension corresponding to 1FL to 11RR.

The estimation of the vibration inputs Fs _FL -Fd _RR will be described. In this embodiment, the individual wheels 11FL-1F
Since the suspension of 1RR is independently controlled, the motion model of each of the wheels 11FL to 11RR is as shown in FIG. Accordingly, the damping coefficients of the shock absorbers at the positions of the wheels 11FL to 11RR are represented by C _FL , C _FR , and C _FL .
_RL , C _RR and suspension spring constants are K _FL , K _FR , K
_Assuming that _RL and _KRR are used, the vibration input transmitted to the vehicle body via the damping element and the spring element is represented by the above equations (5) to (12).

Then, the process proceeds to step S4 to multiply the vibration input on each damping element side by a control gain α, and
Based on the expressions 3) to (16), each wheel 11FL to 11RR
The corresponding vibration input values F _{FL to} F _RR to be controlled are obtained. F _FL = Fs _FL + α · Fd _FL (13) F _FR = Fs _FR + α · Fd _FR (14) F _RL = Fs _RL + α · Fd _RL (15) F _RR = Fs _RR + Α · Fd _RR (16) Here, the control gain α is set to a value smaller than 1, for example, 0.5.

Then, according to the following equations (17) to (20), the preview control force U for canceling the unsprung vibration inputs F _{FL to} F _RR corresponding to the positions of the wheels 11 _FL to 11 _RR.
To calculate the _PFL ~U _{PRR. U PFL = -F FL ··· (17} ) U PFR = -F FR ··· (18) U PRL = -F RL ··· (19) U PRR = -F RR ··· (20) here , (11)-(16) and (17)-
Although the equation (20) and the other equations are different, they may be processed as one each.

Next, the process proceeds to step S5 to calculate the total control force according to the following equations (21) to (24). _{U FL = U N -K B ·} Z VFL + U PFL ··· (21) U FR = U N -K B · Z VFR + U PFR ··· (22) U RL = U N -K B · Z VRL + U in _{PRL ··· (23) U RR =} U N -K B · Z VRR + U PRR ··· (24) wherein, U _N represents the control force necessary to maintain the vehicle height to the target vehicle height, K _B is a bounce control gain.

Next, the process proceeds to step S6, in which values corresponding to the respective total control forces U _{FL to} U _RR calculated in step S5 are output to the D / A converter 45 as pressure command values P _{FL to} P _RR , respectively. Then, the timer interrupt processing ends and the program returns to the predetermined main program. Here, in the above configuration, the stroke sensors 27FL to 27RR, the vertical acceleration sensors 28FL to 28RR, and the processing of steps S1 to S2 in the arithmetic processing unit 44b constitute the unsprung estimation means. Further, the processing in step S3 constitutes a transmission force calculation unit.

Next, the operation of the suspension control device will be described.
Will be described. Now, keep the target vehicle height on a flat road
It is assumed that the vehicle is traveling straight ahead at a constant speed. In this state, the vehicle
Because the target vehicle height is maintained on a flat road,
Stroke sensors 27 arranged in 11FL to 11RR
Each stroke detection value S of FL to 27RR_FL~ S_RRIs almost zero
It has become. Further, no swing occurs in the vehicle body side member 10.
Therefore, the vertical acceleration sensors 28FL to 28RR
Speed detection value Z_GFL~ Z _GRRIs also substantially zero. others
The stroke differential value calculated by the arithmetic processing unit 44b
And the differential value of the sprung displacement is almost zero,
Upper speed Z_VFL~ Z_VRRIs also substantially zero.

[0049] Thus, in a state in which continuing the flat good road running, in the process of FIG. 7 is performed every predetermined sampling time T _S in the microcomputer 44, the unsprung input speed is zero is calculated in step S2 And the vibration inputs Fs _{FL to} Fd _RR calculated in step S3 also continue to be zero, so that the total control forces U _{FL to} U _RR calculated in step S5 are neutral pressure control forces for maintaining the target vehicle height. U _N only becomes a value corresponding, these drive circuits 4 through the interface circuit 44a and a D / a converter 45
Output to 6FL to 46RR.

The driving circuits 46FL to 46RR convert the currents into command currents i corresponding to the pressure command values P _{FL to} P _RR, and the pressure control valves 2 of the wheels 11FL to 11RR respectively.
0FL to 20RR. As a result, the neutral pressure required to maintain the target vehicle height from the pressure control valve is reduced by the hydraulic cylinders 18FL to 18R of the wheels 11FL to 11RR.
R, respectively, and these hydraulic cylinders 18FL-
At 18RR, a thrust for maintaining the stroke at the target vehicle height at each wheel position between the vehicle body-side member 10 and the wheel-side member 14 is generated.

In this straight road traveling state, for example, when the left and right front wheels 11FL and 11FR pass a so-called ramp step road having a step that rises stepwise at the same time, the left and right front wheels 11F and 11FR are stepped up by the front left and right wheels.
As a result, the stroke detection values S _{FL to} S _{RR of} the front wheel side stroke sensors 27FL to 27RR rapidly increase from zero in the positive direction, and an upward acceleration is applied to the front wheel side vehicle body side member 10. Occurs, left and right front wheel 1
1FL, 11FR vertical acceleration sensor 28FL-2
The acceleration detection values Z _{GFL to} Z _{GRR of} 8RR increase in the positive direction.

Then, these stroke detection values S_FL~ S
_RRAnd vertical acceleration detection value Z_GFL~ Z_GRRAnd the microphone
Computer 44
At 44, a predetermined process is performed. That is, at this point,
The unsprung input speed on the rear wheel side calculated in step S2 is zero.
Therefore, the rear wheels 11RL, 1 calculated in step S3
Vibration input Fs for 1RR_RL, Fs_RR, Fd_RL, Fd
_RRMaintains zero state. On the other hand, on the front wheel side,
Stroke detection value S_FL, S_FRAnd vertical acceleration
Detection value Z_GFL, Z _GFRBased on step S2, and
The preview control force on the front wheel side by the process of step S3
U_PFL, U_PFRIs calculated.

[0053] Thus, the general control force U _FL for the front wheel is calculated in step S5, U _FR is step run by vibration input _{Fs FL, Fs FR, Fd FL} , the neutral control force U _N in accordance with the Fd _FR The command value output from the front-wheel-side drive circuits 46FL and 46FR is accordingly reduced. Then, the pressure control valve 20FL, the control pressure P of the front wheel side outputted from 20FR is lowered from neutral pressure U _N, front side of the hydraulic cylinders 18FL, is reduced thrust 18FR, it has been, for the front wheel stroke decreases By doing so, the swing of the vehicle body side member 10 due to the front wheels 11FL and 11FR riding on the step is suppressed.

Further, when an upward acceleration is applied to the vehicle body-side member 10, in step S6, the detected acceleration values Z _{GFL -Z} G
Based on the sprung speeds Z _{VFL to} Z _VRR based on the _GRR, an active control force that suppresses the elevation of the vehicle body-side member 10 by generating a skyhook damper function is generated. Thus, the hydraulic pressure is controlled to be supplied to the hydraulic cylinders 18FL～18RR, vibration input Fs _FL ~Fd _RR in response to road irregularities, is canceled by the該予viewed control force U _PFL ~U _PRR. For this reason, the influence of the road surface unevenness is hardly transmitted to the vehicle body, and a good ride comfort is secured.

At this time, since the front wheels 11FL and 11FR are controlled on the basis of the road surface information detected by the front wheels 11FL and 11FR, there is a dead time in arithmetic processing and a delay in the actuator system, particularly a response delay in the hydraulic control valve. In addition, the estimated vibration input has a phase delay. However, in this embodiment, a small control gain α estimated attenuation side vibration input Fs _FL than 1, to reduce the Fs _FR, the preview control force U _PFL ~U _PRR on the basis of the damping side vibration input of the corrected since seeking, compared with the case of no control, 5H _Z less while maintaining sufficient damping effect on the (sprung resonance frequency range), kept small adverse effects in the high frequency range, the damping overall effect Can be obtained.

Further, when the vehicle runs and the rear wheel side passes through the step rising in the step-like manner, the rear wheels 11RL, 11RR bounce due to the stepping of the left and right rear wheels 11RL, 11RR. , Rear wheel 11RL, stroke sensor 27RL on the 11RR side, 2
The stroke detection values S _RL , S _{RR of} 7RR suddenly increase in the positive direction from zero, and an upward acceleration is generated in the vehicle body side member 10, and the acceleration detection of the vertical acceleration sensors 28RL, 28RR of the left and right rear wheels 11RL, 11RR. Value Z _GRL , Z _GRR
Increases in the positive direction.

In this manner, the same control as described above is performed, and the swing of the vehicle body is suppressed. The above control is performed independently for each of the wheels 11FL to 11RR. Therefore, even when each of the wheels 11FL to 11RR individually rides on the transient convex portion, the above control is performed independently. hand,
The swing of the vehicle body is suppressed. Also, wheels 11FL to 11R
When R temporarily falls into the concave portion, the control reverse to the above is performed to suppress the swinging of the vehicle body. Even when the vehicle runs, the wheels 11FL to 11RR are individually controlled, and the swing of the vehicle body is suppressed.

Further, the four wheels are individually and subject to the target wheel 11F.
Since the road surface information of L to 11RR is directly used and controlled, the front wheels 11FL, 11
Even if the trajectory of the rear wheels 11RL, 11RR deviates from the trajectory of the FR, it is possible to effectively suppress the vibration input to the vehicle body at each of the wheels 11FL to 11RR. As described above, in this embodiment, the rear wheels 11RL and 11RL can be used to detect road surface information without using an expensive non-contact type sensor.
Vibration can be effectively reduced not only on the RR side but also on the front wheels 11FL and 11FR according to road surface displacement.

Further, by controlling all four wheels, not only the rear seats but also the front seats are improved in riding comfort, and the occurrence of pitching behavior is suppressed, so that comfortable riding comfort is secured. In the above embodiment, the control gain α is set to the same value for the front and rear wheels 11FL to 11RR, for example, 0.5, but the control gain α is set to be equal to the front wheels 11FL and 11FR depending on the characteristics of the vehicle. Different control gain values may be set for the rear wheels 11RL and 11RR.

Further, in the above embodiment, the control gain α is described as being fixed, but may be variable. That is, as the control gain α approaches 1, instead of damping effect in 1~5H _Z (sprung resonance frequency range) is increased 6-10
Causes undesirable effects of H _Z (unsprung resonance frequency range), also 6-10 as control gain α approaches zero, instead of damping effect in 1~5H _Z (sprung resonance frequency range) is reduced
Adverse effects of H _Z (unsprung resonance frequency range) is reduced.

In consideration of this, the control gain α is set to 0
It is also possible to have two types of values between 1 and 1 and selectable by a switch (not shown), and the occupant may operate the switch according to the road surface condition, the running condition, and the occupant's preference. The value of the two-stage control gain α is
For example, it is set to 0.2 and 0.8. Alternatively, a knob (not shown) is provided instead of the switch (not shown), and the control gain is set to 0 to 0 by rotating the knob.
You may comprise so that it may change continuously between one.

In the above embodiment, the vehicle body vertical acceleration sensors 28FL to 28RR installed on the vehicle body side member 10 are provided.
Acceleration detection values Z _{GFL to} Z _GRR based on the strokes and stroke detection values S _FL based on the stroke sensors 27FL to 27RR.
By estimating the unsprung input speed by S _RR , the wheels 11FL ~
Although the vibration inputs F _{FL to} F _RR from the 11RR side are estimated, a vertical acceleration sensor is installed on the wheels 11FL to 11RR (unsprung side), and the unsprung force is detected by the acceleration detection value from the vertical acceleration sensor. The input speed and unsprung displacement (road surface displacement) may be calculated.

Further, in the above-described embodiment, the case where the active control of the suspension is performed only based on the vertical acceleration is described. However, the present invention is not limited to this. Alternatively, control signals for suppressing roll, pitch, and bounce based on the detected acceleration values may be calculated, and these may be added to or subtracted from the pressure command values P _{FL to} P _RR to perform total control.

Further, in the above embodiment, the case where the pressure control valves 20FL to 20RR are applied as the control valve has been described. However, the present invention is not limited to this, and other flow control type servo valves or the like may be applied. No problem. Further, in the above embodiment, the microcomputer 44 performs all the arithmetic processing for calculating the unsprung input speed and the like. However, the unsprung input speed is temporarily calculated by an analog circuit including an integrator and a differentiator. May be calculated and then input to the microcomputer 44 via the A / D converter 43. Further, the controller 30 may be configured by combining electronic circuits such as arithmetic circuits without using the microcomputer 44.

In the above embodiment, the working fluid is used as the working fluid.
The case where hydraulic oil was applied was described, but it is not limited to this.
Any fluid that is not compressed and has a low compressibility can be used.
Can be used. In the above embodiment, the actuator
When an active suspension is applied as an
However, the present invention is not limited to this.
Damping of suspensions such as variable force shock absorbers
It may be composed of something that can change the characteristics and spring characteristics.
No.

Next, a second embodiment will be described. The same members and the like as those in the first embodiment will be described with the same reference numerals. The configuration of the second embodiment has the same configuration as that of the first embodiment, and a control gain variable unit described below is added between the processing of step S3 and the processing of step S4 in the microcomputer. I'm just there.

This control gain varying means performs step S4
The processing for automatically selecting the control gain to be used in accordance with the vibration state of the vehicle is performed. That is, the vertical acceleration detection values Z _{GFL to} Z _{GRR for} each wheel input in step S1.
The in each PSD (power spectral den City) treating, the peak level value of the frequency band of 1~5H _Z (sprung resonance frequency range), 6～10H
A peak level value in a frequency band of _Z (unsprung resonance frequency range) is obtained, and peak level values Pl and Ph are calculated by multiplying both peak level values by predetermined weighting factors. The weight coefficients are, for example, 1 to 5 Hz _Z and 6 to 10 H
Human sensitivity is considered to vibration in _Z, when referenced to the sensitivity, generally, since the human sensitivity in vibration of 6～10H _Z than the vibration of 1～5H _Z is high, 6 to 1
The weight coefficient on the 0H _Z side is increased.

Next, the vibration in each frequency range is
Assuming that the level is Pl, the above Pl and Ph are compared, and Pl
(Spring resonance frequency range) is larger, α = a1
If Ph (unsprung resonance frequency range) is larger, α
= A2. This is performed for each wheel. The above a
1, a2 has a relationship of 0 ≦ a1 ≦ a2 ≦ 1, for example,
For example, a1 = 1 and a2 = 0 are set.

The other structure is the same as that of the first embodiment. This
In the second embodiment, the wheels 11FL-
Transmitted from the 11RR to the vehicle via the suspension
When controlling vibration input, vibration at each wheel position is
And the input of the unsprung resonance frequency range is determined to be large
In this case, a small value, for example, “0” is used as the control gain α.
Select the shock absorbers 18FL-18RR
Input Fd transmitted to the vehicle body via _FR ~ Fd _RR According to
The foreseeable control force is reduced, and the sprung resonance frequency range
The vibration damping effect for
The adverse effects of
The effect can be obtained.

On the other hand, when it is determined that the input in the sprung resonance frequency range is large, a large value, for example, “1” is set as the control gain, and the shock absorber 18FL is set.
Vibration input Fd _FR transmitted to vehicle body via 18RR
The control according to the Fd _RR is sufficiently performed, and the control effect on the sprung resonance frequency is increased. At this time, adverse effects in the unsprung resonance frequency range are also emphasized, but since the unsprung resonance frequency range component is small, vibration input transmitted to the vehicle body via the suspension as a whole is reduced.

As described above, according to this embodiment, the road information of the target wheel 11FL to 11RR is used for the wheel 11FL.
Even if the vibration suppression control of the FL to 11RR positions is performed, the optimal vibration suppression control can be automatically performed according to the vibration state of the vehicle body.
Other functions and effects are the same as those of the third embodiment. The control gain varying means in the above examples are not limited thereto, for example, with respect to the vertical acceleration detection value Z _GFL to Z _GRR entered, a band-pass filtering of 1~5H _Z 6~ performs bandpass filtering 10H _Z, taking the square integral value of the output of a constant time unit in both processing, further, compared after multiplied by the appropriate weighting factor to each determined either vibration level is greater Then, it may be determined which of the control gains α is used. At this time, the weighting factor is determined based on the above-described sensitivity of a person or the like.

In the above description of the calculation of the control gain α, one of the two gain values a1 and a2 is selected, but the control gain α is continuously changed between 0 and 1. You may comprise. For example, the acceleration detection value Z _GFL
The Z _GRR, by PSD treating, the peak level in the frequency band of 1~5H _Z (sprung resonance frequency range), 6-1
0H _Z obtains a peak level in the frequency band (unsprung resonance frequency range), each value given by multiplying the weight coefficient each peak level to a peak level of both Pl, calculates the Ph. Next, this is regarded as a vibration level in each frequency range, and each wheel position 11 is calculated based on the following equation (25).
The control gain α for FL to 11RR is determined.

Α = Pl / (Ph + Pl) (25) Based on the above equation (25), the control gain α approaches 1 as the peak level of the sprung resonance frequency region increases, and the unsprung resonance increases. As the peak level in the frequency range increases, the control gain α approaches zero. _{Alternatively,} for the input vertical acceleration detection values Z _{GFL to} Z _GRR ,
Perform bandpass filtering of band-pass filtering and 6～10H _Z of 5H _Z, taking the square integral value of the output of a constant time unit in both processes, the value obtained by multiplying an appropriate weighting factor to each, respectively Jl, Jh, which is regarded as the vibration level at each frequency,
The control gain α is determined based on the equation.

Α = Jl / (Jh + Jl) (26) Based on the above equation (26), the control gain α approaches 1 as the peak level of the sprung resonance frequency range increases, and the unsprung resonance increases. The control gain α approaches 0 as the peak level in the frequency range increases. Further, in the above two embodiments, the vibration level in the sprung resonance frequency range and the vibration level in the unsprung resonance frequency range are compared, and
The control gain α is changed by determining that the input of the sprung resonance frequency is large or the input of the sprung resonance frequency is large, but only the vibration level in one of the resonance frequency ranges is detected and the vibration level is detected. May be configured to change the control gain α according to the absolute change of the input value. Next, a suspension control device according to a third embodiment will be described. The same members and the like as in the first embodiment will be described with the same reference numerals.

The basic structure of the suspension control device according to the second embodiment is similar to that of the first embodiment.
As shown in FIG. 8, step S of the first embodiment in the arithmetic processing of the microcomputer 44 of the controller 30 is performed.
The only difference is the processing of step S14 corresponding to No. 4. In the second embodiment, in the processing of step S14 of the microcomputer 44, the vibration-side input Fd _{FL to} Fd
_The force corresponding to _RR is calculated as the cutoff frequency fc calculated above.
And calculates the predictive control force U _PFL ~U _PRR after performing the low pass filtering process in _{FL ~fc RR.}

[0076] That is, the processing procedure of the processing unit 44b in the microcomputer 44 of the microcomputer 44 of the second embodiment, it will be explained according to the flowchart of FIG. 8, a predetermined sampling time T _S (e.g., 20ms
ec) is executed as a timer interrupt process. First, in step S11, stroke detection values S _FL -S _RR and vehicle body vertical acceleration detection values Z _GFL -Z _GRR corresponding to the respective wheels 11FL-11RR are read, and step S12 is executed. Move to

In step S12, each wheel 11
Stroke detection values S _{FL to} S _RR corresponding to _{FL to 11 RR}
And the wheels 11FL to 11R that accurately follow the road surface shape based on the vehicle body vertical acceleration detection values Z _{GFL to} Z _GRR.
Estimating the differential value of the road surface change of R, that is, the unsprung input speed,
Move to step S13. The process of estimating the unsprung input speed is the same as the process of step 2 of the first embodiment.

Next, in step S13, the unsprung input speeds of the wheels 11FL to 11RR calculated above are integrated to calculate unsprung displacements (road surface displacements) X _{FL to} X _RR. (5) based on the lower displacement
The calculation of Expression (8) is performed from the expression. by this,
At the positions of the wheels 11FL to 11RR, spring-side vibration inputs Fs _{FL to} Fs _RR transmitted to the vehicle body via a coil spring 36, which is a spring element of the suspension, and to the vehicle body via shock absorbers 18FL to 18RR, which are damping elements. The transmitted damping-side vibration inputs Fd _{FL to} Fd _RR are calculated. The processing in step S13 is the same as the processing in step S3 in the first embodiment.

[0079] Then, the processing proceeds to step S14, on the basis of the following (27) to (39) below, with respect to the force on the spring side vibration input calculated above Fs _FL ~Fs _RR, predetermined cut-off frequency fc, for example, by implementing the low pass filter process with 4H _Z, it obtains the vibration input value to be controlled corresponding each wheel 11FL～11RR. F _FL = f (Fs _FL ) + Fd _FL (27) F _FR = f (Fs _FR ) + Fd _FR (28) F _RL = f (Fs _RL ) + Fd _RL (29) F _RR = F (Fs _RR ) + Fd _RR (30) Here, f represents a function representing a low-pass filter.

Next, according to the following equations (31) to (34), the preview control force U for canceling the unsprung vibration inputs F _{FL to} F _RR corresponding to the positions of the wheels 11 _FL to 11 _RR.
To calculate the _PFL ~U _{PRR. U PFL = -F FL ··· (31} ) U PFR = -F FR ··· (32) U PRL = -F RL ··· (33) U PRR = -F RR ··· (34) where , (27) to (30), and (31) to
Although described as an operation expression different from expression (34), one operation expression may be used.

Next, the process proceeds to step S15, where the first
The total control forces U _{FL to} U _RR are calculated according to equations (21) to (24) in step S5 of the embodiment. Next, the process proceeds to step S16, in which the control forces U _{FL to} U _RR calculated in step S15 are output to the D / A converter 45 as pressure command values P _{FL to} P _RR , respectively, and the timer interrupt process ends. To return to the predetermined program.

Next, the operation of the suspension control device will be described. Now, it is assumed that the vehicle is traveling straight ahead at a constant speed on a flat good road while maintaining the target vehicle height. In this state, since the vehicle is maintaining the target vehicle height on a flat good road, the stroke detection values S _{FL to} S _RR of the stroke sensers disposed on the wheels 11FL to 11RR are substantially zero. . Also,
Since the body-side member 10 does not swing, the acceleration detection values Z _GFL -Z of the vertical acceleration sensors 28FL-28RR are detected.
_{GRR is} also almost zero. Therefore, the arithmetic processing unit 44
Since the stroke differential value and the differential value of the sprung displacement calculated in b are substantially zero, the sprung speeds Z _{VFL to} Z _VRR
Is also substantially zero.

[0083] Thus, in a state in which continuing the flat good road traveling, a microcomputer 44, in the process of FIG. 8 to be carried out every predetermined sampling time T _S, the unsprung input speed calculated in step S12 Since the state becomes zero and the vibration inputs F _{FL to} F _RR calculated in step S13 also continue to be zero, the total control force U _{FL to} U _RR calculated in step S15 is the neutral pressure control force for maintaining the target vehicle height. U
_{N, which} are values corresponding to only _N. These values are transmitted via the interface circuit 44a and the D / A converter 45 to the drive circuit 46
Output to FL-46RR.

For this reason, the drive circuits 46FL to 46RR convert the currents into command currents i corresponding to the pressure command values P _{FL to} P _RR, and the pressure control valves 2 of the wheels 11FL to 11RR respectively.
0FL to 20RR. As a result, the neutral pressure required to maintain the target vehicle height from the pressure control valves 20FL to 20RR is increased by the hydraulic cylinder 1 of each wheel 11FL to 11RR.
8FL to 18RR.
FL to 18RR generate a thrust for maintaining the stroke between the vehicle body-side member 10 and the wheel-side member 14 at the target vehicle height.

When the vehicle is traveling straight on a good road, for example, when the front left and right wheels simultaneously pass the ramp step road, the front wheels 11FL and 11FR bounce due to the stepping of the front left and right wheels 11FL and 11FR. 11FL, 11FR side stroke sensor 27FL ~
The stroke detection values S _{FL to} S _RR of 27RR rapidly increase from zero in the positive direction, and an upward acceleration is generated in the vehicle body-side member 10, and the acceleration detection values of the vertical acceleration sensors 28FL, 28FR of the left and right front wheels 11FL, 11FR. Z _{GF L,} Z
_GFR increases in the positive direction.

Then, these stroke detection values S_FL~ S
_RRAnd vertical acceleration detection value Z_GFL~ Z_GRRAnd the microphone
Computer 44
At 44, a predetermined process is performed. That is, at this point,
On the rear wheel side, the unsprung input speed calculated in step S12
And the unsprung displacement are zero, and thus are calculated in step S13.
Input F to the rear wheels 11RL, 11RR_RL, F
_RRMaintains zero state. On the other hand, on the front wheel side,
Stroke detection value S_FL, S_FRAnd vertical acceleration
Detection value Z_GFL, Z _GFRBased on the front wheels 11FL, 11
FR's preview control force U_PFL, U_PFRIs calculated.

Thus, the total control forces U _FL , U _FL of the front wheels 11FL, 11FR calculated in step S14.
_FR is step run by vibration input F _FL, is lower than the neutral control force U _N according to F _FR, accordingly, the front wheels 11F
The command values output from the drive circuits 46FL, 46FR on the L, 11FR side are reduced, whereby the pressure control valve 20F
L, the front wheels 11FL outputted from 20FR, control pressure P 11FR side is lower than the neutral pressure U _N, the front wheels 11FL,
The thrust of the hydraulic cylinders 18FL to 18RR on the 11FR side is reduced, and the stroke of the front wheels 11FL and 11FR is reduced, so that the swing of the vehicle body side member 10 due to the front wheels 11FL and 11FR riding on a step is suppressed.

Further, when an upward acceleration is applied to the vehicle body-side member 10, in step S6, the detected acceleration values Z _{GFL to} Z _GFL -Z
Based on the sprung speeds Z _{VFL to} Z _VRR based on the _GRR, an active control force that suppresses the elevation of the vehicle body-side member 10 by generating a skyhook damper function is generated. At this time, the front wheels 11F
Front wheel 11F based on road surface information detected by L, 11FR
Since L and 11FR are controlled, a phase delay occurs due to a calculation processing time and a delay of the actuator system, particularly a response delay of the hydraulic control valve. In view of the fact that this phase delay is remarkable in the high frequency region, in the present embodiment, in step S14, the coil spring 36, which is a spring element, is used.
Through out the spring-side vibration input which is estimated to be inputted to the vehicle body side, by cutting a high frequency component by a low-pass filtering to suppress the adverse effect of the high frequency of the control force of the preview control force U _PFL ~U _PRR since high frequency components, for example, it is possible to lower the vibration peaks of the vibration of the vehicle body around with 8H _Z, it is possible to suppress the unsteady steps sensitive due to vibration in the vicinity 3~8H _Z.

The other structures, operations and effects are the same as those of the first embodiment. In the above embodiment, the cutoff frequency fc of the low-pass filter processing is described as being constant, but may be variable. That is, as the cut-off frequency fc is lowered, the damping effect in the frequency range near 1～2H _Z instead of damping effect at frequencies above the vicinity of 2.2H _Z increases decreases. Further, as the cut-off frequency fc is close to zero, instead of damping effect at frequencies above the vicinity of 2.2H _Z becomes smaller damping effect in the frequency range near 1～2H _Z increases.

In consideration of this, there are two kinds of values as the cutoff frequency fc, and one of the cutoff frequencies fc can be selected in advance by a switch (not shown).
The occupant may change the state by operating the switch according to the road surface state or the running state, and further according to the occupant's preference. The value of the cut-off frequency of the second stage is set to, for example, 3H _Z and 7H _Z like. Alternatively, a knob (not shown) is provided in place of the switch (not shown),
By rotating the knob, the cutoff frequency becomes 3
May be configured to steplessly vary between ~7H _Z.

Next, a fourth embodiment will be described. The same members and the like as those in the third embodiment will be described with the same reference numerals. The configuration of the fourth embodiment has the same configuration as that of the third embodiment, and a cut-off frequency variable unit described below is added between the processing of step S13 and the processing of step S14 in the microcomputer. It is just that.

The cut-off frequency varying means performs a process for selecting a cut-off frequency to be applied to the low-pass filter processing in step S14. That is, step S
The vertical acceleration detected value Z _GFL to Z _GRR entered in 11 by PSD treated, determined with the peak level value of the frequency band of 1～2H _Z, the peak level value of the frequency band of 3～7H _Z , Respectively, by multiplying the respective peak levels by a predetermined weighting coefficient to calculate corrected peak level values Pl and Ph. The weighting factors, for example 1～5H _Z and 6-1
Human sensitivity is considered to vibration at 0H _Z, when referenced to the sensitivity, generally, than 1~2H _Z 3
Since the human sensitivity at high ~7H _Z, a large weighting coefficient 3～7H _Z side. In addition, the width is more of 4~7H _Z is 4
Since it is twice as large, it is necessary to further weight about 4: 1.

Next, this is regarded as the vibration level in each frequency range, and the above Pl and Ph are compared.
The greater the better the (1~2H _Z), and fc = 7H _Z,
The greater the direction of Ph (3 to 7), and fc = 3H _Z. Next, the process proceeds to step S15, where the force of canceling the vibration input from the unsprung state is reduced by the step S1.
The low-pass filter processing is performed at the cutoff frequency fc calculated in step 4 to estimate the vibration input Fs _FR .
Each control force U after removing the high frequency component to Fs _RR
To calculate the _PFL ~U _PRR.

In this embodiment, in step S14,
If the vibration input of 3～7H _Z is determined to be larger, the
The cutoff frequency fc is set to a small value, and
Control effect is lowered relative to the vibration of the H _Z but, 3~8H _Z
The adverse effects in the vibration range are also kept small. On the other hand, 1-2
When the input of the H _Z region is determined to be larger, the cut-off frequency fc is set to a large value, the control effect on vibration range of 1～2H _Z increases. Although adverse effect on the vibration range of 3～8H _Z is highlighted, the vibration frequency component of said 3～8H _Z vibration input that is transmitted to the vehicle body through the suspension as a whole is smaller is reduced.

As described above, according to the present embodiment, even when the vibration control of the target wheel is performed based on the road surface information of the target wheel, the optimum vibration control is automatically performed in accordance with the vibration state of the vehicle body. Becomes possible. Other configurations, operations and effects are the same as those of the third embodiment. The means for calculating the cutoff frequency to be processed by the cutoff frequency varying means in the fourth embodiment is not limited to this. For example, for the input vertical acceleration detection values Z _{GFL to} Z _GRR , 1-2H
The band pass filter processing of _{Z and} the band pass filter processing of 3 to 7 Hz _Z are performed, the square integral value of the output in a fixed time unit in both processes is obtained, and each is multiplied by an appropriate weighting factor and compared. The cutoff frequency fc may be determined by determining whether the vibration level is large.

In the calculation of the cutoff frequency fc, one of the two values has been described.
The cutoff frequency fc may be configured to continuously change according to the vehicle vibration state. For example, by subjecting the acceleration detection values Z _{GFL to} Z _GRR to PSD processing, 1-2H _Z
And peak level in the frequency band, obtains the peak level in the frequency band of 3～7H _Z, the peak level Pl after correction respectively multiplied by a predetermined weighting factor to the peak level of both, to calculate the Ph. Next, this is regarded as the vibration level in each frequency range, and the cutoff frequency fc is determined based on the following equation (35).

[0097] fc = (3 · Ph + 7 · Pl) / (Ph + Pl) ··· (35) Based on the above (35), the cut-off frequency fc as towards the peak level of 1～2H _Z region increases 3
Approaches H _Z, the cut-off frequency fc as towards the peak level of 3～7H _Z range is increased closer to 7H _{Z. Alternatively} , the input vertical acceleration detection values Z _{GFL to} Z _GRR
Against, 3 and band-pass filtering 1～2H _Z
Performs bandpass filtering 7H _Z, taking the square integral value of the output of a constant time unit in both processes, the value obtained by multiplying an appropriate weighting factor to each, respectively Jl, and Jh, which at each frequency Considering the vibration level, the cut-off frequency fc _FL based on the following equation (36)
~ Fc _RR is determined.

[0098] fc = (3 · Jh + 7 · Jl) / (Jh + Jl) ··· (36) Based on the above expression (36), the cut-off frequency fc as towards the peak level of 1～2H _Z region increases 7
Approaches H _Z, the cut-off frequency fc as towards the peak level of 3～7H _Z range is increased closer to 3H _Z. In the above embodiment, by comparing the vibration level of the vibration level and 3～7H _Z zone 1～2H _Z range, relatively,
Input 1～2H _Z is large, or, although by changing the cut-off frequency fc is determined that a large input of 1～2H _Z, by detecting only the vibration level of one frequency band, the vibration level May be configured to change the cutoff frequency fc according to the absolute change of the input value.

Further, in the first and second embodiments, the vibration gains Fd _{FL to} Fd _RR estimated to be input to the vehicle body via the damping element of the suspension are multiplied by the control gain α smaller than 1. after obtains the preview control force U _PFL ~U _PRR counteract vibration input F _FL to F _RR to be input to the vehicle body from the road surface through the suspension, also in the third and fourth embodiments, the spring element of the suspension Vibration input Fs _{FL to} Fs _RR estimated to be input to the vehicle body via
After a low-pass filter process is applied to the vehicle from the road surface via a suspension via a vibration input F _FL ~
While seeking preview control force U _PFL ~U _PRR counteract F _RR, both processes may be performed simultaneously.

That is, the vibration inputs Fd _{FL to} Fd _RR estimated to be input to the vehicle body via the damping element of the suspension
Is multiplied by a control gain α smaller than 1, and a low-pass filter process is performed on the vibration inputs Fs _{FL to} Fs _RR estimated to be input to the vehicle body via the spring elements of the suspension. The sum of the vibration input and the spring-side vibration input is regarded as the vibration input input to the vehicle body from the road surface via the suspension, and the vibration inputs F _FL to F _FL
It may be obtained predictive control force U _PFL ~U _PRR counteract _RR.

In this case, both actions of both processes
Effect is exerted, as compared with the case of not carrying out the control, while sufficiently maintaining the damping effect near the sprung resonance frequency range, it is possible to suppress the vibration input of around 8H _Z. At this time, as described in the second embodiment and the fourth embodiment, the control gain α and the cutoff frequency fc are made variable according to the vibration state of the vehicle, and fine vibration reduction corresponding to the vibration state of the vehicle is performed. May be implemented.

Next, a fifth embodiment will be described. The same members as those in the first embodiment will be described with the same reference numerals. In all the above embodiments, the left and right front wheels 11F
L, 11FR and the left and right rear wheels 11RL, 11RR are individually subjected to suspension control at the wheels 11FL to 11RR based on information on the road surface positions at the wheels 11FL to 11RR.

On the other hand, in the fifth embodiment, the front wheels 11
For the suspension control for the FL and 11FR sides, the suspension control described in the first embodiment is performed, but for the rear wheels 11RL and 11RR, the front wheels 11
The suspension control is performed based on the road surface information detected on the FL, 11FR side. The basic configuration of the suspension control device of the fifth embodiment is the same as that of the first embodiment except that the processing by the controller 30 is different, and a vehicle speed sensor for detecting the vehicle speed is provided. The vehicle speed signal can be supplied to the controller 30. However, on the rear wheels 11RL and 11RR, the wheels 11
Since it is not necessary to detect a stroke between the RL and 11RR and the vehicle body, no stroke sensor is provided on the rear wheels 11RL and 11RR.

Next, the controller 3 in the fifth embodiment will be described.
0 will be described. The controller 30 is a front wheel 11F
L, 11FR side stroke sensors 27FL, 27FR
Detection values S _FL and S _FR input from the
Vertical acceleration sensor 28F at positions 1FL to 11RR
Body vertical acceleration detected value output from L~28RR Z _GFL ~Z _GRR and respectively changes the digital value A /
A D converter 43, a microcomputer 44 to which an A / D conversion output of the A / D converter 43 is input, and pressure command values P _{FL to} P _RR output from the microcomputer 44.
Are supplied via D / A conversion values, and are converted into drive currents i _{FL to} i _RR for the pressure control valves 20 _{FL to 20 RR.} I have.

The microcomputer 44 includes at least an interface circuit 44 a and an arithmetic processing unit 44.
b and a storage device 44c. The conversion output of the A / D converter 43 is input to the interface circuit 44a, and each pressure control valve 20F from the arithmetic processing unit 44b is input to the interface circuit 44a.
Pressure command values P _{FL to} P _RR for L to 20 _RR are output to D / A converter 45.

The arithmetic processing unit 44b performs processing to be described later.
And a predetermined sampling time T _S (Eg 2
0 msec), the stroke detection value S _FL ~ S _RR And on the body
Reading the downward acceleration detection, the front wheels 11FL, 11F
Fineness of the road surface displacement transmitted to the vehicle body from the unsprung position at the R position
The vibration input of the front wheels 11FL and 11FR is
Each front wheel 11FL is estimated based on the estimated value.
Hydraulic cylinder 18 as an actuator of 11RR
Foreseeing control force U generated at FL to 18RR _PFL ~ U _PRR To
Calculate.

At the same time, the differential value of the road surface displacement is detected as the vehicle speed.
Between the front and rear wheels 11RL, 11RR calculated based on the values.
A predetermined number of stages formed in the storage device 44c together with the extension time τ
While sequentially shifting to the storage area corresponding to the shift register.
The delay time τ is sampled when shifting.
Time T_SAre sequentially subtracted and stored, and the delay time τ is
Based on the differential value of the road surface displacement that has reached zero, the rear wheels 11RL,
Hydraulic cylinder 18 as actuator on 11RR side
Foreseeing control force U generated by RL and 18RR_PRL,U _PRRAct
Calculate. Furthermore, the degree at each wheel 11FL-11RR position
Vertical direction of each vehicle body from acceleration sensors 28FL-28RR
Acceleration detection value Z_GFL~ Z_GRRVehicle body vertical speed Z
_VFL~ Z_VRRDemonstrate skyhook damper function based on
For active control for each of the wheels 11FL to 11RR
Calculate the force and add the two control forces to each pressure control valve 2.
Pressure command value P for 0FL to 20RR_FL~ P_RRAs
Output to the D / A converter 45.

The storage device 44c stores a program necessary for the arithmetic processing of the arithmetic processing device 44b in advance, and sequentially shifts the differential value of the road surface displacement to be read every predetermined sampling time T _S together with the delay time τ. While a shift register area capable of storing a predetermined number is provided.
It is memorable.

Next, the operation of the above embodiment will be described with reference to the flowchart of FIG. The processing in FIG. 9 is performed for a predetermined sampling time T _S (for example, 20 msec).
It is executed as a timer interrupt process for each timer. First, in step S21, each stroke detection value S _FL , S _FR corresponding to each front wheel 11FL, 11FR and the vehicle vertical acceleration detection value are read, and the current vehicle speed detection value detected by the vehicle speed sensor is read. S22
Move to

In step S22, each of the front wheels 11
Stroke detection values S _FL , S _FR corresponding to FL, 11FR
And the front wheels 11FL, 11F that accurately follow the road surface shape based on the vehicle vertical acceleration detection values Z _GFL , Z _GFR.
The differential value of the road surface change at the R position, that is, the unsprung input speed is estimated, and the process proceeds to step S23. The process of estimating the unsprung input speed is performed by differentiating the stroke detection values S _FL and S _FR to calculate the stroke speed, and integrating the vehicle body vertical acceleration detection values Z _GFL and Z _GFR to differentiate the sprung displacement. Calculate the value. Next, by adding the stroke speed and the differential value of the sprung displacement, the differential value of the road surface displacement at each of the front wheels 11FL and 11FR that accurately follows the road surface shape is output.

In step S23, each of the front wheels calculated above is calculated.
Integrates the unsprung input speed of 11FL and 11FR and unsprung
Displacement (road displacement) X_FL, X_FRAnd calculate the above
Based on the force velocity and the unsprung displacement, the following equation (37)
The calculation of the equation (40) is performed respectively. This allows
Of the suspension at the positions of the wheels 11FL and 11FR.
Transmitted to the vehicle body via the coil spring, which is a spring element
Spring-side vibration input Fs _FL, Fs_FR, And the damping element
Damping side transmitted to the vehicle body via the shock absorber
Vibration input Fd_FL, Fd_FRIs calculated.

Fs _FL = K _FL · X _FL (37) Fs _FR = K _FR · X _FR (38) Fd _FL = C _FL · (dX _FL / dt) (39) Fd _FR = C _FR · (dX _FR / dt) (40) where C _FL , C _FR , C _RL , and C _RR represent the damping coefficient of the shock absorber corresponding to each wheel, respectively, and K _FL , K
_FR , K _RL , and K _RR each represent a spring constant of a suspension corresponding to each wheel.

Then, the process proceeds to step S24 to multiply the vibration input on the damping element side at each front wheel position by the control gain α, and to perform the vibration to be controlled corresponding to each front wheel based on the following equations (41) and (42). Find the input value. F _FL = Fs _FL + α · Fd _FL (41) F _FR = Fs _FR + α · Fd _FR (42) Here, the control gain α is a value smaller than 1 such as 0.05. Is set.

Next, the process proceeds to step s25, where the front wheels 11FL, 11FL,
Vibration input F _FL , F from unsprung corresponding to 11FR position
To calculate the foreseeable control force U _PFL ~U _PRR to cancel the _{FR. U PFL = -F FL ··· (43} ) U PFR = -F FR ··· (44) , where the description, (41), and (42) Formula (43),
Although equation (44) and equation (4) are described as different arithmetic equations, each may be one arithmetic equation.

Then, the flow shifts to step S26, where the following equation (45) is calculated based on the read vehicle speed detection value V, and the rear wheels 11RL and 11RR reach the road surface on which the front wheels 11FL and 11FR have passed. The delay time τ until the calculation is performed is calculated. τ = (L / V) −τ _S (45) where L indicates a wheel base, τ _S is a delay time of the control system, and a response delay of the hydraulic system and the controller 30
Is represented by an added value such as a dead time.

[0116] Then, the processing proceeds to step 27, unit time T _s per made in deviation from the current vehicle speed detection value V (n) and the sampling time T _S only before the last vehicle speed detection value V (n-1) Of the wheel base L
Is divided by the change speed ΔV to calculate a delay time correction value Δτ. Next, the process proceeds to step S28, in which the differential value (unsprung input speed) and the delay time τ of the calculated road surface displacement are stored at the head position of the shift register area formed in the storage device 44c, and stored up to the previous time. The differential value of the road surface change and the delay time τ are sequentially shifted. At this time, when shifting the delay time τ, the sampling time T _S and the calculated delay time correction value Δτ are updated from the delay time τ at each shift position and stored as updated new delay times τ.

Next, the process proceeds to step S29 to read out the differential value of the oldest road surface change stored in the shift register area, that is, the differential value of the road surface change in which the delay time τ has become zero. The value and the delay time τ corresponding thereto are deleted from the shift register area. Then, step S
30, the road surface change is estimated by integrating the differential value of the road surface change read in step S29. Based on the differential value of the road surface change and the road surface change, the following equation (46) and (4) are used.
The vibration inputs F _RL and F _RR from the rear wheels 11 _RL and 11 _RR that will be generated on the rear wheels 11 _RL and 11 _RR are calculated based on the calculation of the equation 7).

F _RL = C _RL · (dX _RL / dt) + K _RL · X _RL (46) F _RR = C _RR · (dX _RR / dt) + K _RR · X _RR (47) And C _RL and C _RR are the respective rear wheels 11RL and 11RL, respectively.
Represents the damping coefficient of the shock absorber corresponding to RR,
K _RL and K _RR represent the spring constants of the suspensions corresponding to the rear wheels 11RL and 11RR, respectively.

[0119] Further, the following equation (48) and (49) by executing calculation of equation, the rear wheels 11RL, preview control force U _PRL for the pressure control valve 20FL~20RR the 11RR side, U
Calculate the _PRR . U _PRL = −F _RL (48) U _PRR = −F _RR (49) Here, for the sake of explanation, equations (46) and (47) and (48),
Equation (49) is described as another arithmetic expression, but may be one arithmetic expression.

Then, the flow shifts to step S31, where the wheels 11FL to 11FL are calculated according to the following equations (50) to (53).
The total control force U _{FL to} U _RR for 11RR is calculated. _{U FL = U N -K B ·} Z VFL + U PFL ··· (50) U FR = U N -K B · Z VFR + U PFR ··· (51) U RL = U N -K B · Z VRL + U _{PRL ··· (52) U RR =} U N -K B · Z VRR + U PRR ··· (53) wherein, U _N represents the control force necessary to maintain the vehicle height to the target vehicle height, K _B is a bounce control gain.

Next, the flow shifts to step S32, where the above
Each control force U calculated in step S31_FL~ U_RRThe pressure finger
Price P_FL~ P_RROutput to the D / A converter 45 as
The timer interrupt processing is terminated and the specified program
Return to system. Next, the operation of the suspension control device is described.
Explain the work. Now, maintain the target vehicle height on a flat road
It is assumed that the vehicle is traveling straight ahead at a constant speed. In this state, the vehicle
Is maintaining the target vehicle height on a flat, good road.
Stroke sensor 2 disposed on wheels 11FL and 11FR
7FL, 27FR stroke detection value S_FL, S_FRIs almost zero
It has become. Further, no swing occurs in the vehicle body side member 10.
Therefore, the vertical acceleration sensors 28FL to 28RR
Speed detection value Z_GFL~ Z_{GR R}Is also substantially zero. others
The stroke differential value calculated by the arithmetic processing unit 44b
And the differential value of the sprung displacement is almost zero,
Upper speed Z_VFL, Z _VFRIs also substantially zero.

[0122] Thus, in a state in which continuing the flat good road traveling, a microcomputer 44, in the process of FIG. 9 is performed every predetermined sampling time T _S, the unsprung input speed calculated in step S22 The state becomes zero, and the vibration inputs F _FL and F _FR calculated in step S23 also remain in the state of zero. For this reason, the differential value of the road surface displacement after the elapse of the delay time τ calculated in step S26 is also zero, and the rear wheels 11RL,
11RR side of preview control force U _PRL, U _PRR also becomes zero, whereas sprung speed Z _VFL, since Z _VFR is also at zero, the overall control force U _FL ~U _RR calculated in step S31 maintained at the target vehicle height to become a value corresponding only to the neutral pressure control force U _N, these interface circuits 44a and D / a converter 4
5 to the drive circuits 46FL to 46RR.

For this reason, each of the driving circuits 46FL to 46RR
Is converted into a command current i corresponding to the pressure command values P _{FL to} P _RR and supplied to the pressure control valves 20FL to 20RR of the wheels 11FL to 11RR, respectively. As a result, the neutral pressure required to maintain the target vehicle height from the pressure control valve is increased by the hydraulic cylinders 18FL to 18R of the wheels 11FL to 11RR.
R, respectively, and these hydraulic cylinders 18FL-
At 18RR, a thrust for maintaining the stroke between the vehicle body side member 10 and the wheel side member 14 at the target vehicle height is generated.

When the left and right front wheels 11FL and 11FR simultaneously pass on a ramp step road in the straight running state on the good road, the front wheels 11FL and 11FR bounce due to the stepping of the left and right front wheels 11FL and 11FR, whereby the front wheels 11FL and 11FR bounce. stroke sensor 27FL arranged on the front wheel side, the stroke detection value S _FL of 27FR, with S _FR increases rapidly in a positive direction from zero, the front wheel vehicle body member 1
0, an upward acceleration occurs, and the left and right front wheels 11FL, 11
The acceleration detection values Z _GFL and Z _{GFR of the} FR vertical acceleration sensors 28FL and 28FR increase in the positive direction.

The stroke detection values S _FL , S
_{The FR} and the vertical acceleration detection values Z _GFL and Z _GFR are input to the microcomputer 44, and the microcomputer 44 performs predetermined processing. That is, by executing the processing from step S21 to step S25, which is the same processing as step S1 to step 5 in the first embodiment, the detected stroke detection value is applied to the front wheels 11FL and 11FR. Based on S _FL , S _FR and the vertical acceleration detection values Z _GFL , Z _GFR , the preview control force _UPFL ,
_UPFR is calculated.

Further, in step S26, the front wheel 1
The rear wheels 11RL, 11
Calculate the delay time τ until RR arrives, store this and the differential value of road surface displacement in the head area of the shift register area, and sequentially calculate the differential value of zero road surface displacement and the delay time τ up to the previous time. Shift one by one. At this time, a value obtained by subtracting the sampling time T _S and the delay time correction value Δτ calculated in step S27 from each delay time τ is updated as a new delay time τ.

At this point, the data is stored in the shift register area.
The differential value of each road surface displacement up to the last time is zero.
Then, the rear wheels 11RL and 11R calculated in step S30
Preview control force U for R_PRL,U_PRRMaintains zero state
I do. As a result, the front wheels calculated in step S31
11FL, 11FR total control force U_FL, U_FRBut the step
Vibration input F by riding_FL, F_FRNeutral control force according to
U_NAnd accordingly, the front wheels 11FL, 1
Output from the drive circuits 46FL to 46RR on the 1FR side
The command value decreases, and as a result, the pressure control valves 20FL to 20FL
Control of front wheels 11FL and 11FR output from 0RR
Pressure P is neutral pressure P _NLower than the front wheels 11FL, 11
Thrust of hydraulic cylinders 18FL and 18FR on FR side decreases.
And the stroke of the front wheels 11FL and 11FR decreases.
Before the skyhook damper function is exhibited
Car body side member by stepping on wheels 11FL and 11FR
The swing of 10 is suppressed.

After that, when the front wheels 11FL, 11FR have passed through the ramp step road, the front wheels 11FL, 11FR are again turned on.
For 1FR, the overall control force U _FL to maintain the target vehicle height,
To return to the value of U _FR. However, the rear wheels 11RL, 11RR
At the time when the delay time τ calculated in step S26 becomes zero, that is, when the rear wheels 11RL and 11RR pass through the ramp step road,
The differential value of the road surface change when the front wheels 11FL and 11FR climb over a step is read, and based on these, the rear wheels 11R and 11FR are read.
L, preview control force U _PRL for 11RR, since U _PRR is calculated, can be affected by the road surface irregularities with little transmitted to the vehicle body, to ensure a good riding comfort.

In addition, when a vertical acceleration is applied to the vehicle body-side member 10 on the rear wheels 11RL and 11RR, the acceleration is detected by the vertical acceleration sensors 28FL to 28RR on the rear wheels 11RL and 11RR. Wheel 11R
The sprung speeds Z _{VRL and} Z _VRR at the L and 11RR positions are calculated, and an active control force for suppressing the elevation of the vehicle body-side member 10 by exerting a skyhook damper function is exerted, whereby the pressure control valve 20RL _, 20RR is controlled, the hydraulic pressure supplied to the hydraulic cylinders 18RL, 18RR is controlled, and the swing of the vehicle body is suppressed.

In the fifth embodiment, step S2
In the processing of 4, when calculating the vibration input to be controlled on the front wheels 11FL and 11FR side, based on the processing of the first embodiment, a fixed control gain smaller than 1 is applied to the vibration input Fd _FL . Although Fd _RR is multiplied, the control gain may be variably controlled according to the vibration state of the vehicle body based on the processing of the second embodiment. Further, based on the third or fourth embodiment, a predetermined low-pass filter process is performed on the vibration input transmitted to the vehicle body via the estimated spring element of the suspension to further control the front wheels. You may make it improve.

In the fifth embodiment, the rear wheels 11RL, 1RL are controlled to control the skyhook damper function.
Vertical acceleration sensors 28FL-28RR on 1RR side
However, when the control of the skyhook damper function is not performed, it is not necessary to provide the vertical acceleration sensors 28RL, 28RR on the rear wheels 11RL, 11RR side. As described above, the cost of the suspension control device is reduced as compared with the above-described first or second embodiment, because the stroke sensors 27RL and 27RR and the vertical acceleration sensors 28RL and 28RR are not required on the rear wheels 11RL and 11RR. I do.

In all of the above embodiments, four vertical acceleration sensors 28FL to 28RR are provided for each wheel.
However, three vertical direction sensors are disposed at arbitrary positions that are not aligned with each other with respect to the vehicle, and each of the three vertical direction sensors is detected by the detected values from the three vertical direction acceleration sensors. The vertical acceleration of the wheel position may be estimated.

[0133]

As described above, according to the suspension control device of the present invention, based on the road surface information of the target wheel position, the vibration input from the target wheel to the vehicle body via the suspension can be effectively performed. There is an effect that reduction can be achieved. As a result, each suspension control for all four wheels of the front and rear wheels is controlled without using expensive non-contact type sensors, and by controlling the vibration input input to the vehicle body from under the spring, so that dust, Vibration is stably reduced without errors due to mud, water drops, snow pools, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of a controller according to a first embodiment of the present invention.

FIG. 3 is a characteristic diagram illustrating a relationship between a control current and a command current of the pressure control valve according to the embodiment of the present invention.

FIG. 4 is a characteristic diagram showing output characteristics of the stroke sensor according to the embodiment of the present invention.

FIG. 5 is a characteristic diagram showing output characteristics of the vertical acceleration sensor according to the embodiment of the present invention.

FIG. 6 is an explanatory view showing a vehicle model having one degree of freedom per wheel.

FIG. 7 is a flowchart showing a processing procedure of the microcomputer of the first embodiment according to the present invention.

FIG. 8 is a flowchart showing a processing procedure of a microcomputer according to a third embodiment of the present invention.

FIG. 9 is a flowchart showing a processing procedure of a microcomputer according to a fifth embodiment of the present invention.

FIG. 10 is a characteristic diagram showing a transmission characteristic to a vehicle body with respect to a road surface change when there is no countermeasure for a response delay.

FIG. 11 is a characteristic diagram showing a transmission characteristic to a vehicle body with respect to a road surface change when a control gain smaller than zero is set.

FIG. 12 is a characteristic diagram showing a transmission characteristic to a vehicle body with respect to a road surface change when a control gain is changed.

FIG. 13 illustrates a case where a low-pass filter process is performed.
FIG. 4 is a characteristic diagram illustrating transmission characteristics to a vehicle body with respect to a road surface change.

FIG. 14 is a characteristic diagram showing a transmission characteristic to a vehicle body with respect to a road surface change when a cutoff frequency of a low-pass filter is changed.

FIG. 15 is a characteristic diagram showing a transmission characteristic to a vehicle body with respect to a road surface change when a control gain is set and low-pass filter processing is performed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Body-side member 11FL-11RR Wheel 18FL-18RR Hydraulic cylinder 20FL-20RR Pressure control valve 22 Hydraulic source 27FL-27RR Stroke sensor 28FL-28RR Vertical acceleration sensor 30 Controller 44 Microcomputer 46FL-46RR Control valve drive circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-319066 (JP, A) JP-A-4-201615 (JP, A) JP-A-63-64810 (JP, A) JP-A-61-1986 166715 (JP, A) JP-A-61-135811 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60G 17/015

Claims (5)

(57) [Claims] An actuator which is interposed between a wheel and a vehicle body and generates a control force capable of controlling a vertical stroke between the wheel and the vehicle body by a control signal, and estimates a vibration input transmitted from a road surface to a suspension. Unsprung motion estimating means, and transmission force calculating means for calculating each vibration input transmitted from the unsprung to the vehicle body through the spring element and the damping element of the suspension based on the estimated value of the unsprung motion estimating means, A control for canceling a vibration input obtained as a sum of a vibration input value obtained by subjecting a vibration input value for a spring element to a low-pass filter process and a vibration input value for the damping element based on each calculated value of the transmission force calculating means. And a control means for supplying a signal to the actuator. 2. An actuator interposed between a wheel and a vehicle body for generating a control force capable of controlling a vertical stroke between the wheel and the vehicle body according to a control signal, and estimating a vibration input transmitted from a road surface to a suspension. Unsprung motion estimating means, and transmission force calculating means for calculating each vibration input transmitted from the unsprung to the vehicle body through the spring element and the damping element of the suspension based on the estimated value of the unsprung motion estimating means, Control means for supplying a control force for canceling the vibration input to the actuator based on each vibration input value calculated by the transmission force calculation means, wherein the control means sets the vibration input value for the damping element to On the other hand, the vibration input value obtained as the sum of the vibration input value after multiplication by a control gain smaller than 1 and the vibration input value after low-pass filtering of the vibration input value for the spring element. Suspension control unit and supplying a control signal to cancel the value. 3. A suspension control system as claimed in 請 Motomeko 2 characterized in that a control gain varying means for changing in accordance with the control gain for the vibration input of the damping element content in the vibration state of the vehicle. 4. A control signal interposed between a wheel and a vehicle body.
The vertical stroke between the wheel and the vehicle body can be controlled by
An actuator that generates control force and a suspension pen
Unsprung motion estimation to estimate the vibration input transmitted to the
Means based on the estimated value of the unsprung motion estimating means.
From unsprung through the spring and damping elements of the pension
Transmission force calculation means for calculating each vibration input transmitted to the vehicle body
If, based on each calculated value of the transmission force calculation means, the damping requirements
Multiply the primary vibration input value by a control gain smaller than 1.
Of the vibration input value after the
The control signal for canceling the vibration input obtained as a sum
And control means for supplying the control gain to the vibration input of the damping element.
Provided control gain variable means that changes according to the vibration state
A suspension control device, characterized in that: Wherein said low-pass filtered suspension controller according to cut-off frequency to claim 1 or claim 2, characterized in that a cut-off frequency changing means for changing in accordance with the vibration state of the vehicle .