JPH05319068A - Suspension control device - Google Patents

Abstract

PURPOSE:To provide a suspension control device which prevents a rapid change in comfortability near the boundary between a car speed for which expected control is possible and a car speed for which control is impossible by providing a control stop means which stops generating an expected control force when the determination results of a car speed determination means is outside the range of speed of the vehicle to be controlled. CONSTITUTION:A front road information detector 41 detects information about a road at the front by means of wheels and a car speed detection means 26 detects a car speed. A control means 44 then causes actuators 18RL, 18RR to generate an expected control force calculated based on the detected front road information delayed by the detected car speed detection value. In this case, a car speed determination means 44c in a control means 44 determines whether or not the car speed detection value of the car speed detection means 26 is within the range of speed of the vehicle to be controlled. If the car speed determination means 44c finds that the value is outside this range, a control stop means in the control means 44 stops generating an expected control force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects front road surface information indicating road surface displacement at a position in front of a wheel to be controlled, and based on this road surface information, a stroke of an actuator interposed between a vehicle body and a wheel to be controlled. The present invention relates to an improvement of a suspension control device for predictive control of a vehicle.

[0002]

2. Description of the Related Art As a conventional suspension control device for performing preview control, there is one disclosed in Japanese Patent Laid-Open No. 61-135811. This conventional example is a vehicle shock absorber including a wheel that is driven to rotate along a road surface and a spindle mechanism that supports the wheel and a vehicle body at a predetermined distance, and that drives the spindle mechanism according to the unevenness of the road surface. And a control unit for instructing expansion and contraction at the predetermined interval based on a signal of the detection unit and a traveling speed signal, the detection unit being configured in front of the wheel traveling and configured to detect the unevenness. And a valve drive mechanism that excites an electromagnetic valve so as to inject or discharge hydraulic pressure to the spindle mechanism according to the command.

[0003]

However, in the above-described conventional suspension control device, since the preview control is performed over the entire vehicle speed range, the vehicle speed is high, and the road surface unevenness in front of the control target wheel is prevented. Prediction control is not in time between the detection and the arrival of the wheels,
It may not be possible to perform accurate preview control, such as when the vehicle speed is too low and the time it takes for the wheels to reach the detected road surface irregularities is too long to hold the detected road surface information. When the predictive control cannot be performed correctly, or when the predictive control can be accurately performed, or vice versa, the riding comfort changes abruptly depending on the presence or absence of the predictive control at the boundary point, causing the passengers to feel uncomfortable. There was an unsolved problem of causing it.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above-mentioned conventional example, and specifies the control range, and changes the preview control force gently near the boundary of the specified control range. It is an object of the present invention to provide a suspension control device that improves ride comfort.

[0005]

In order to achieve the above object, a suspension control device according to a first aspect of the present invention is arranged between a wheel and a vehicle body as shown in the basic configuration diagram of FIG. An actuator that generates a control force capable of controlling a stroke between them by a signal, a front road surface information detection unit that detects road surface information in front of the wheel, a vehicle speed detection unit that detects a vehicle speed, and a front road surface information in the actuator. In the suspension control device, comprising: a control means for generating a preview control force calculated based on a value obtained by delaying the front road surface information of the detection means according to the vehicle speed detection value of the vehicle speed detection means, wherein the control means is Vehicle speed determination means for determining whether the vehicle speed detection value of the vehicle speed sensor is within the control target vehicle speed range, and the determination result of the vehicle speed determination means is outside the control target vehicle speed range. It is characterized in that said and a control stop means for stopping the generation of the preview control force Rutoki.

Here, when the vehicle speed changes from outside the control target range to within the control target range or vice versa, the control gain of the preview control force can be gradually changed according to the vehicle speed change or the elapsed time. In addition to being desirable, it is preferable to have a hysteresis characteristic in order to prevent hunting when the control gain changes.

[0007]

In the suspension control device according to the first aspect, when the vehicle speed determining means determines that the vehicle speed is out of the control target range, the control stopping means stops the generation of the preview control force, so that the vehicle is running at low speed and at high speed. The riding comfort is improved by avoiding the inaccurate preview control during traveling and performing the preview control only within the control target range where the characteristic preview control can be performed.

At this time, when the vehicle speed changes from outside the controlled range to within the controlled range or vice versa, by gradually increasing or decreasing the control gain with the change of the vehicle speed or the passage of time, A sudden change in the control force at the boundary between the preview control state and the non-preview control state is prevented, and further, by providing a hysteresis characteristic, hunting at the boundary is prevented.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic configuration diagram showing a first embodiment of the present invention, in which 10 is a vehicle body side member, 11FL to 11RR are front left to rear right wheels, and 12 is a suspension control device.

The suspension control device 12 includes hydraulic cylinders 18FL to 18RR as actuators which are respectively interposed between the vehicle body side member 10 and the wheel side members 14 of the wheels 11FL to 11RR, and the hydraulic cylinders 18FL to 18RR.
Pressure control valves 20FL to 20RR for individually adjusting the working pressure of
And a hydraulic pressure source 22 that supplies the pressure control valves 20FL to 20RR with hydraulic oil of a predetermined pressure via the supply side pipe 21S and collects the return oil from the pressure control valves 20FL to 20RR via the return side pipe 21R. An accumulator 24F, 24R for accumulating pressure, which is inserted in the supply pressure side pipe 21S between the hydraulic pressure source 22 and the pressure control valves 20FL to 20RR, a vehicle speed sensor 26 that detects a vehicle speed and outputs a pulse signal corresponding thereto. Stroke sensors 27FL and 27FR that are arranged in parallel with the front wheel side hydraulic cylinders 18FL and 18FR to detect relative displacement between the front wheels 11FL and 11FR and the vehicle body, and the up and down of the vehicle body at positions corresponding to the wheels 11FL to 11RR, respectively. Vertical acceleration sensors 28FL to 28RR for individually detecting the vertical acceleration, and vertical acceleration sensors 28FL
To 28RR, the respective pressure control valves 20FL to 20RR are actively controlled based on the vertical acceleration detection values Z _{GFL to} Z _GRR , and each sensor 26, 27FL, 27FR and 28FL to 28FR.
The controller 30 for predicting the output pressures of the rear wheel side pressure control valves 20RL and 20RR individually according to the motion state of the front wheels based on the detection value of

Each of the hydraulic cylinders 18FL to 18RR has a cylinder tube 18a.
A lower pressure chamber L separated by a piston 18c having an axial through hole is formed in 8a.
Thrust is generated according to the pressure difference between the upper and lower surfaces and the internal pressure.
The lower end of the cylinder tube 18a is the wheel-side member 1
4 and the upper end of the piston rod 18b is attached to the vehicle body side member 10. Further, each of the pressure chambers L has a pressure control valve 20FL to 20RR via a hydraulic pipe 38.
Connected to the output port of. Also, the hydraulic cylinder 1
Each of the pressure chambers L of 8FL to 18RR is connected to an accumulator 34 for absorbing unsprung vibration via a throttle valve 32. A coil spring 36, which has a relatively low spring constant and supports a static load of the vehicle body, is disposed between the upper and lower springs of each of the hydraulic cylinders 18FL to 18RR.

Each of the pressure control valves 20FL to 20RR has a conventionally known three-port proportional electromagnetic pressure reducing valve having a cylindrical valve housing in which a spool is slidably mounted and a proportional solenoid integrally provided therein. (For example, JP-A-64-7
No. 4111). Then, by adjusting the command current i (command value) supplied to the exciting coil of the proportional solenoid, the movement distance of the poppet accommodated in the valve housing, that is, the position of the spool is controlled, and the supply port and the output port or the output are controlled. The hydraulic oil flowing between the hydraulic power source 22 and the hydraulic cylinders 18FL to 18RR can be controlled via the port and the return port.

The relationship between the command current i (: i _{FL to} i _RR ) applied to the exciting coil and the control pressure P output from the output port of the pressure control valve 20FL (to 20 _RR ) is shown in FIG. As described above, when the minimum current value i _MIN taking noise into consideration, the minimum control pressure P _NIM is reached. When the current value i is increased from this state, the control pressure P increases linearly in proportion to the current value i, and the maximum control pressure P _NIM increases. When the current value is i _MAX , the maximum control pressure P _MAX corresponding to the set line pressure of the hydraulic power source 22 is obtained. This Figure 3
I _N is the neutral command current, and P _CN is the neutral control pressure.

As shown in FIG. 4, each of the stroke sensors 27FL and 27FR has a neutral voltage V _{S of} zero and a vehicle height higher than the target vehicle height when the vehicle height matches a preset target vehicle height. The stroke detection values H _FL and H _FR, which are a positive voltage corresponding to the deviation and a negative voltage corresponding to the deviation when the vehicle height becomes lower than the target vehicle height, are output.

As shown in FIG. 5, each of the vertical acceleration sensors 28FL to 28RL has a zero voltage when the vertical acceleration is zero, and a positive voltage corresponding to the acceleration value when the upward acceleration is detected. When the analog voltage and the downward acceleration are detected, the vertical acceleration detection values Z _{GFL to} Z _GRR , which are negative analog voltages corresponding to the acceleration value, are output.

The controller 30, as shown in FIG.
Stroke detection values S _FL and S _FR input from the stroke sensors 27 _FL and 27 _FR and the vertical acceleration sensor 28.
Acceleration sensor 28FL corresponding to the front wheel side of FL to 28RR
And 28FR vertical acceleration detection value Z output from 28FR
_{Based on the GFL} and Z _GFR , the vibration input estimation circuit 41 that outputs differential values x _1FL ′ and x _1FR ′ of the road surface displacement of the front wheels 11FL and 11FR that accurately follow the road surface shape, and the vertical acceleration sensors 28FL to 28FR The vertical acceleration detected values Z _{GFL to} Z _GFR are integrated to integrate the sprung speed Z _{VFL to} Z _VFL
For example, an integrator circuit 4 configured by a bandpass filter that calculates a _VRR that passes a frequency near the sprung resonance frequency.
2FL to 42RR, differential values x _0FL ′ and x _0FR ′ of the road surface displacement output from the vibration input estimation circuit 41, and the integration circuit 4
Sprung speed output from 2FL to 42RR Z _{VFL to} Z _VRR
A / D converters 43a to 43f for converting the data into digital values
And a microcomputer 44 to which the vehicle speed detection value V of the vehicle speed sensor 26 and the A / D conversion outputs of the A / D converters 43a to 43f are inputted, and pressure command values P _{FL to} P outputted from the microcomputer 44. _RR is D / A converter 45
It is supplied through FL to 45RR, and these are supplied to the pressure control valve 20.
A drive circuit 4 configured by, for example, a floating type constant voltage circuit for converting into drive currents i _{FL to} i _FR for _{FL to} 20 RR
It has 6FL-46FR.

Here, the vibration input estimating circuit 41 differentiates the stroke detection values S _FL and S _FR of the stroke sensors 27 _FL and 27 _FR, as shown in FIG.
Calculate _VFL and S _VFR , for example, 2 of unsprung resonance frequency
Differentiating circuits 41a and 41b configured by a high-pass filter having a cut-off frequency f _HC of about double, and vehicle body vertical acceleration detection values Z _GFL and Z _GFR of vertical acceleration sensors 28FL and 28FR are integrated to determine the sprung displacement. Differential value x
_FL ′ and x _FR ′ are calculated, for example, 1 on the sprung resonance frequency.
The stroke speed S output from the integrating circuits 41c and 41d and the differentiating circuits 41a and 41b, which are composed of low-pass filters having a cutoff frequency f _LC of about / 6.
And an adder 41e and 41f adds the _VFL and the differential value x _FL 'and x _FR' the sprung displacement output from the S _VFR and the integration circuit 41c and 41d, an adder 4
Front wheels 11 that accurately follow the road surface shape from 1e and 41f
Differential values of road displacement of FL and 11FR x _0FL ′ and x _0FR ′
Is output. That is, the stroke detection values S _FL and S output from the stroke sensors 27 FL and 27 _FR.
FR represents the relative displacement between the unsprung part and the unsprung part, as expressed by the following formulas (1) and (2).
It is a value obtained by subtracting the unsprung displacement x _FL and x _FR of the vehicle body from the unsprung displacement x _0FL and x _{0FR of 1FR} .

S _FL = x _0FL -x _FL (1) S _FR = x _0FR -x _FR (2) Therefore, the stroke detection values S _FL and S _FR are differentiated by the differentiation circuits 41a and 41b. The differentiated stroke velocities S _VFL and S _VFR are differential values x _0FL ′ and x _0FR ′ of the unsprung displacement, _respectively .
Since the differential values x _FL ′ and x _FR ′ of the sprung displacement are subtracted from these, these and the vertical acceleration detection values Z _GFL and Z
By adding the differential value of the integral of the sprung displacement of the _GFR x _FL 'and x _FR', the true road displacement offset to follows the road surface displacement a differential value x _FL sprung displacement 'and x _FR' It is possible to obtain the differential values x _0FL ′ and x _0FR ′ of.

The microcomputer 44 has at least an input side interface circuit 44a, an output side interface circuit 44b, an arithmetic processing unit 44c and a storage unit 44d. The input interface circuit 44a includes
The vehicle speed detection value V and the conversion outputs of the A / D converters 43a to 43f are input, and the pressure command values P _FL to the pressure control valves 20FL to 20RR are output from the output side interface circuit 44b.
P _RR is output to the D / A converters 45FL to 45RR. Further, the arithmetic processing unit 44c executes the processing of FIG. 7 described later, and at every predetermined sampling time T _S (for example, 20 msec), the vehicle speed detection value V, the differential value x _0FL ′ of the road surface displacement,
x _0FR ′ and vehicle body vertical speeds Z _{VFL to} Z _VRR are read to determine whether the vehicle speed detection value V is within the control target range. When the vehicle speed detection value V is within the control target range, the control gain G is set according to the vehicle speed. The delay time τ between the front and rear wheels is set and the differential values x _0FL ′, x _0FR ′ of the road surface displacement are calculated based on the vehicle speed detection value V.
Together with _R , they are stored in the storage device 44d while being sequentially shifted to a storage area corresponding to a predetermined number of stages of shift registers.
The delay time τ _R is stored while sequentially subtracting the sampling time T _S when shifting, and based on the differential values x _0FL ′, x _0FR ′ of the road surface displacement at which the delay time τ _R reaches zero and the control gain G. The predictive control forces U _RL and U _RR generated by the hydraulic cylinders 18RL and 18RR as actuators on the rear wheel side are calculated, and the skyhook is calculated based on the vehicle body vertical velocities Z _{VFL to} Z _VRR from the integrating circuits 42FL to 42RR. A control force for active control that exerts a damper function is calculated, and a value obtained by adding both control forces is output to the D / A converters 45FL to 45RR as a pressure command value for each pressure control valve 20FL to 20RR.

Further, the storage device 44d stores a program necessary for the arithmetic processing of the arithmetic processing device 44c in advance, and the differential values x _0FL ′, x _0FR ′ of the road surface displacement read at every predetermined sampling time T _S. Is formed along with the delay time τ _R , a shift register area for storing a predetermined number is formed, and a gain management map indicating the relationship between the vehicle speed detection value V and the control gain G is stored in advance. The calculation results required in the calculation process are sequentially stored. As shown in FIG. 8, the gain management map is set to “0” between the vehicle speed detection value V and the lower limit vehicle speed setting value _VL , and when the vehicle speed detection value V is equal to or higher than the lower limit vehicle speed setting value _VL , the vehicle speed detection value is set. It increases with an increase in V, saturates at a vehicle speed V _L1 reaching “1”, and then decreases with an increase in a vehicle speed detection value V from a vehicle speed V _H1 before the upper limit vehicle speed set value V _H , and then reaches an upper limit vehicle speed. set value V _H "0", and the is configured to continue the "0" exceeds the upper limit vehicle speed setting value V _H. At this time, the lower limit vehicle speed set value _VL side and the upper limit vehicle speed set value _VH side have different rates of change in the control gain with respect to the vehicle speed, and the control gain G changes from "0" to "1" or vice versa. The time required for this is set to be substantially equal on the low speed side and the high speed side.

Next, the operation of the above embodiment will be described with reference to the flowchart of FIG. 6 showing the processing procedure of the arithmetic processing unit 44c in the microcomputer 44. That is,
The process of FIG. 6 is performed at a predetermined sampling time T _S (for example, 20 ms
ec) is executed as a timer interrupt process. First, in step S1, the current vehicle speed detection value V (n) of the vehicle speed sensor 26 is read, and then the process proceeds to step S2 to detect the vehicle speed detection value V.
The control gain G is calculated by referring to the gain management map stored in advance in the storage device 44d based on (n), and then the process proceeds to step S3.

In step S3, the differential values x _0FL ′, x _0FR ′ of the road surface displacement from the vibration input estimation circuit 41 and the vehicle body vertical velocities Z _{VFL to} Z from the integration circuits 42FL to 42FR.
Reads the _VFR, then the process proceeds to step S4, the unit consisting of the side of 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) time T _S
The change speed ΔV per hit is calculated, and the wheel base L is divided by the change speed ΔV to calculate the delay time correction value Δτ.

Next, at step S5, the following equation (3) is calculated based on the detected vehicle speed value V, and the front wheel 11FL is calculated.
Then, the delay time τ _R until the rear wheels 11RL and 11RR reach the road surface where 11FR and 11FR have passed is calculated. τ _R = (L / V) -τ _S (3) where L is the wheelbase, τ _S is the delay time of the control system, and the response delay τ ₁ of the hydraulic system and the computation dead time of the controller It is represented by the sum of τ ₂ and the phase delay τ ₃ due to the filter.

Next, in step S6, the differential value x _0FL ′, x of the road surface displacement read in step S3 is read.
_0FR ′ and the delay time τ _R calculated in step S5 are stored at the head position of the shift register area formed in the storage device 44d, and the differential values x _0FL ′, x _{0FR of the} road surface displacement stored up to the previous time are stored. ′ And the delay time τ _R are sequentially shifted. At this time, regarding the delay time τ _R , when shifting, a new delay time τ is obtained by subtracting the sampling time T _S and the delay time correction value Δτ calculated in step S4 from the delay time τ _{R at} each shift position. Update as _R and store.

Next, in step S7, the oldest or delay time τ stored in the shift register area is set.
The differential values x _0FL ′, x _0FR ′ of the road surface displacement where _R becomes zero are read out, and the following equations (4) and (5) are calculated based on these, and the rear wheel pressure control valve 20RL is calculated. And the prediction control forces U _pRL and U _pRR for _{20 RR} are calculated, and the read differential values x _0FL ′, x _0FR ′ of the oldest road surface displacement and the delay time τ _{R corresponding} thereto are deleted from the shift register area.

U _pRL = − [C _p + {1 / (ω ₁ + s)} K _p ] x _0FL ′ ... (4) U _pRR = − [C _p + {1 / (ω ₁ + s)} K _p ] x _0FR ′ (5) where C _p is the damping force control gain, K _p is the spring force control gain, and ω ₁ is the control cutoff frequency f _C multiplied by 2π. And the damping coefficient C of the actual suspension
And C _p ≦ C, K _p ≦ K for the spring constant K, and ω ₁ ≧ 0.

Here, the reason why the _preview control forces U _pRL and U _pRR are calculated according to the above equations (4) and (5) is that they are active in the unsprung resonance frequency region as in the case of a normal active suspension. When the control is not performed and the vibration is suppressed mainly in the sprung resonance frequency region of 5 Hz or less, the motion model of one wheel has a spring element K and a damping element C on the road surface as shown in FIG.
It can be considered as a one-degree-of-freedom model in which the sprung mass M is arranged above these and the control element U in parallel, and the external force F acts on this sprung mass M. In FIG. 9, X ₀ is road surface displacement and X is sprung displacement.

The equation of motion of this one-wheel one-degree-of-freedom model can be expressed as M ″ X ₀ = C (X ₀ ′ −X ′) + K (X ₀ −X) −F + U (6) Solving this equation (6) for the sprung displacement X, Becomes

For example, in the equation (4), x _0FL ′ = s
Since x _0FL , this formula (4) is _expressed by ω ₁ = 0, C _p = C,
Substituting into equation (7) with K _p = K, equation (7) yields Becomes

If the estimation accuracy of the road surface displacement in this equation (8) is sufficiently high, then (X ₀ −x _0FL ) _≈0 . The effect of uneven road surface is hardly transmitted to the vehicle body,
A good ride quality can be obtained.

Then, the process proceeds to step S8 and the following (1
The total control forces U _{FL to} U _RR are calculated according to the equations (0) to (13). _{U FL = U N -K B ·} Z VFL ............ (10) U FR = U N -K B · Z VFR ............ (11) U RL = U N -K B · Z VRL + G · U _{pRL ............ (12) U RR =} U N -K B · Z VRR + G · U pRR ............ (13) wherein, U _N is control necessary to maintain the vehicle height to the target vehicle height Force, K _B is the bounce control gain, G is the step S2
It is the control gain calculated in.

Next, in step S9, the control forces U _{FL to} U _RR calculated in step S8 are output as pressure command values to the D / A converters 45 _{FL to} 45 _RR , respectively, and then a timer interrupt process is performed. Upon completion, the program returns to the predetermined main program. Here, the processing of FIG. 7 corresponds to the control means, and the gain management map corresponding to FIG. 8 and step S2.
The processing of step S8 corresponds to the vehicle speed determination means and the control stop means, respectively.

Therefore, if it is assumed that the vehicle has started running from the stopped state, the control gain G is "0" as shown in FIG. 8 until the vehicle speed detection value V reaches the lower limit vehicle speed set value _VL . In order to maintain the
1FR passes through a so-called ramp step road, which is a step in which the road surface rises stepwise, and the differential value x _0FL ′ and x _0FR ′ of the road surface displacement is negative from the vibration input estimation circuit 41 due to the stroke change of the suspension at that time. Even if the _preview control forces U _pRL and U _pRR are calculated after being input to the microcomputer 44 and being delayed by the delay time τ _R according to the vehicle speed, (12) in step S8. Since the control gain G is zero in the equations and (13), the _preview control forces U _pRL and U _pRR are treated as zero, which is based on the differential values x _0FL ′ and x _0FR ′ of the road displacement on the front wheel side. Preview control of the rear wheel side is stopped, the sprung speed Z _VFL to Z _VRR the vertical acceleration detection value Z _GFL to Z _GRR integrated over the integration circuit 42FL~42RR road irregularities passage when the vertical acceleration sensor 28 Body of the swing is suppressed by only brute active control force.

After that, when the vehicle speed detection value V increases and becomes equal to or higher than the lower limit vehicle speed setting value _VL , the control gain G gradually increases from "0" as the vehicle speed detection value V increases. When the front wheels 11FL and / or 11FR pass through the unevenness of the road surface during this period, the differential value x _0FL ′ and x of the road surface displacement accurately corresponding to the road surface shape is obtained from the vibration input estimation circuit 41.
_0FR 'is output, and in response thereto, the differential value _x0FL ' and _x0FR 'of the road surface displacement is _transferred to the front wheel 1 by the microcomputer 44.
Rear wheels 11RL and 11RR on the road where 1FL and 11FR have passed
There was a shift delay with time tau _R stored in the shift register at every sampling time T _S until it reaches the delay time due to the change of the delay time tau _R therefrom sampling time T _S and the vehicle speed for each shift position for each shift Correction value Δτ
Is updated as a new delay time τ _R , and the _preview control forces U _pRL and U _pRR are calculated based on the differential values x _0FL ′ and x _0FR ′ of the road surface displacement at which the delay time τ _R becomes zero. ..

Therefore, the rear wheels 11RL and 11RR are the front wheels 1.
When the vehicle reaches the road surface through which 1FL and / or 11FR has passed, the front wheels 11FL and 11FR read differential values x _0FL ′ and x _0FR ′ of the road surface displacement when the front wheels 11FL and 11FR pass through the uneven road surface, and the rear wheels are read based on these values. On the other hand, the _preview control forces U _pRL and U _pRR are calculated according to the equations (4) and (5), and are corrected to the _preview control force according to the control gain G at that time in step S8, and the pressure on the rear wheel side is corrected. It is output to the control valves 20RL and 20RR. As a result, the vehicle speed detection value V becomes the lower limit vehicle speed setting value V.
_In the transient state where _L is reached, the control gain G gradually increases in accordance with the vehicle speed detection value V, so that the preview control force for the rear wheels gradually increases, and it is possible to prevent the occupant from feeling uncomfortable. Meanwhile, the preview control can be started.

After that, when the vehicle speed detection value V reaches the vehicle speed set value V _L1 , the control gain G becomes "1".
As expressed by the equation (9), the influence of the road surface unevenness is hardly transmitted to the vehicle body, the optimum preview control is executed, and a good riding comfort can be secured. Moreover, when an upward acceleration is generated in the vehicle body side member 10 on the rear wheel side due to the step-up of the rear wheels 11RL and 11RR, this acceleration is detected by the vertical acceleration sensors 28RL and 28RR, and is integrated by the integrating circuits 42RL and 42RR. Integrated sprung speed Z _VRL
Since Z _VRR and Z _VRR are input to the microcomputer 44, an active control force that exerts the skyhook damper function and suppresses the rise of the vehicle body side member 10 is generated in step S8, which causes the pressure control valves 20RL and 20RR to operate. By being controlled, the hydraulic pressure supplied to the hydraulic cylinders 18RL and 18RR is controlled, and the swing of the vehicle body is suppressed.

After that, when the vehicle speed detection value V increases and reaches the vehicle speed V _H1 before the upper limit vehicle speed setting value V _H , the control gain increases as the vehicle speed detection value V increases, contrary to the above-described low speed operation. Since G gradually decreases, the preview control force is gradually decreased, and when the upper limit vehicle speed set value V _H is reached, the control gain G becomes zero and the preview control is stopped. In this case as well, the preview control force gradually decreases, so that the preview control can be stopped without giving the occupant a feeling of strangeness.

Next, a second embodiment of the present invention will be described with reference to FIG. This second embodiment is one in which the vehicle speed detected value so as to prevent hunting in the case of fluctuations in the vicinity of the lower limit vehicle speed setting value V _L and the upper limit vehicle speed detecting value V _H of the control target range. In the second embodiment, instead of the case where the control gain G is calculated by referring to the control gain management map in the processing of step S2 of FIG. 7 in the arithmetic processing unit 44c described above, the control gain calculation subroutine shown in FIG. Execute the process.

That is, in step S21, the vehicle speed detection value V (n) is the minimum vehicle speed V _{13 at} which the control gain G is always G _MAX.
If V (n) <V ₁₃ , it is determined whether the vehicle speed detection value V (n) is smaller than the previously read vehicle speed detection value V (n-1). It is determined whether it is large or not. This determination is to determine whether or not the vehicle is in an accelerating state. When V (n)> V (n-1), it is determined that the vehicle is in an accelerating state, and the process proceeds to step S23. Then, it is determined whether or not the current control gain G is equal to or higher than the acceleration function f _1a (V) represented by the following equation (15). This decision is
It is determined whether or not it is larger than the control gain G determined by the acceleration characteristic curve L _{1a in} FIG. 11, and G ≧ f _1a
If it is (V), it is judged that the deceleration state is reversed to the acceleration state, the processing is terminated without updating the control gain G, and the process proceeds to step S3 in FIG.
When <f _1a (V), it is determined that the acceleration state is continued, the process proceeds to step S24, and the control gain G is set.
After updating to the acceleration function f _1a (V) represented by the equation (15), the processing is terminated and the process proceeds to step S3 in FIG.

[0040]

[Equation 1]

On the other hand, the determination result of step S22 is V (n).
When ≤V (n-1), it is determined that the vehicle is in the deceleration state, the process proceeds to step S25, and the current control gain G
Is less than or equal to the deceleration function f _1d (V) represented by the following equation (16), and when G ≦ f _1d (V), it means that the acceleration state is reversed to the deceleration state. If it is determined that the control gain G is not updated and the process is terminated, the process proceeds to step S3 of FIG. 7, and if G> f _1d (V), it is determined that the deceleration state is continued, After shifting to S26, the control gain G is set to the deceleration function f _1d represented by the equation (16).
After updating to (V), the process ends and step S3 in FIG.
Move to.

[0042]

[Equation 2]

Further, the determination result of step S21 is V
When (n) ≧ V ₁₃ , the process proceeds to step S27, and it is determined whether or not the vehicle speed detection value V (n) exceeds the maximum vehicle speed V _{23 at} which the control gain G is always G _MAX, and V ( n) ≤
If V ₂₃ , the process proceeds to step S28 to set the control gain G to G _MAX , then the process ends, and the process proceeds to step S3 of FIG. 7. If V (n)> V ₂₃ , step S29 Move to.

In step S29, the vehicle speed detection value V
It is determined whether (n) is larger than the vehicle speed detection value V (n-1) read last time. This determination is to determine whether the vehicle is in an accelerating state or a decelerating state, and V (n)> V (n-
When it is 1), it is determined that the vehicle is in an accelerating state, the process proceeds to step S30, and it is determined whether the current control gain G is the acceleration function f _2a (V) or less represented by the following equation (17). , G
When ≦ f _2a (V), it is determined that the deceleration state is in the acceleration state, and the processing is terminated without updating the control gain and the process proceeds to step S3 in FIG.
When G> f _2a (V), it is determined that the acceleration state is continued, the process proceeds to step S31, and the control gain G is set to the acceleration function f _2a (V) represented by the equation (17). After updating, the process is terminated and the process proceeds to step S3 in FIG.

[0045]

[Equation 3]

Furthermore, when the result of the determination in step S29 is V (n) ≤V (n-1), it is determined that the vehicle is in a decelerating state, and the process proceeds to step S32, where the current control gain G is (18) below. It is determined whether or not the deceleration function f _2d (V) represented by the formula is greater than or equal to, and when G ≧ f _2d (V), it is determined that the acceleration state is reversed to the deceleration state, and the control gain is set. Without updating, the process is terminated and step S in FIG.
3 and when G <f _2d (V), it is determined that the deceleration state is continued and the process proceeds to step S33, where the control gain G is the deceleration function f _2d (V ), The process is terminated and the process proceeds to step S3 in FIG.

[0047]

[Equation 4]

According to the second embodiment, assuming that the vehicle starts and accelerates from the stopped state in which the control gain G is set to "0", the vehicle speed detection value V (n) is set to the set vehicle speed V. Until step ₁₁ is reached, step S21 to step S2
After step 2, the process proceeds to step S23, and since the function f _1a (V) is “0”, G ≧ f _1a (V), so the control gain G is not updated and the state of “0” is maintained. ..

When the vehicle speed exceeds the set vehicle speed V ₁₁ , the function f _1a (V) represented by the equation (15) increases as the vehicle speed detection value V (n) increases. G <
It is determined that f _1a (V), the control gain G is updated to the acceleration function f _1a (V) by increasing in step S24, and the control gain G is increased while continuing the acceleration state thereafter.
_When the vehicle speed detection value V (n) exceeds the set vehicle speed V ₁₃ by increasing in accordance with _{1a, the process} proceeds from step S21 to step S27 to step S28, and the control gain G is set to G _MAX .

Thereafter, when the vehicle decelerates, the vehicle speed detection value V
When (n) becomes less than the set vehicle speed V ₁₃ , step S2
From 1 to step S22, since it is in the deceleration state, it moves to step S25, and the deceleration function f calculated by the equation (16)
_{Since 1d} (V) is larger than the maximum gain G _MAX , G ≦ f
_The control gain G is not updated because it is determined to be _1d (V), but when the vehicle speed detection value V (n) becomes less than the set vehicle speed V ₁₂ , the function f _1d (V) becomes smaller than the maximum gain G _MAX. Since the value becomes a value, the control gain G is reduced by shifting from step S25 to step S26, and the control gain G is gradually reduced while continuing the deceleration state thereafter, and a hysteresis characteristic can be obtained.

On the other hand, the detected vehicle speed V (n) is equal to the set vehicle speed V _1-
When the deceleration state is reversed to the acceleration state in the state between V ₁₃ , the process proceeds from step S22 to step S23, and the deceleration function f _1d (V) at this time is always smaller than the current control gain G. Until the deceleration function f _1d (V) becomes less than the current control gain G, the control gain G is maintained at a constant value and then decreases. Conversely, when the acceleration state is changed to the deceleration state, the steps S22 to S2 are performed.
5, the acceleration function f _1a (V) at this time always becomes a value less than the control gain G, so the control gain G is kept until the acceleration function f _1a (V) becomes larger than the current control gain G. The value is maintained at a constant value and then increases, so that the hysteresis characteristic is exhibited and hunting due to a change in vehicle speed can be prevented.

Similarly, the detected vehicle speed V (n) is equal to the set vehicle speed V _23.
When it was also reversed to the deceleration state of the same accelerated conditions described above when a between ~V _2, the value is the control gain G to reach a vehicle speed lower than the current control gain G of the deceleration function f _2d (V) is constant The control gain is maintained and then decreased, and in the opposite case, the control gain is maintained at a constant value and then decreased until the value of the acceleration function f _2a (V) reaches a vehicle speed increasing from the current control gain G. Therefore, the hysteresis characteristic can be exhibited, and hunting due to vehicle speed fluctuation can be prevented.

In the above embodiment, the case where the control gain is changed according to the change in the vehicle speed detection value V has been described, but the present invention is not limited to this, and the vehicle speed detection value V (n) is the set vehicle speed. when from the state of less than V ₁ becomes set vehicle speeds V _{1 to} more, or the vehicle speed detection value V (n) is set vehicle speed V ₂
When the vehicle speed becomes equal to or lower than the set vehicle speed V ₂ from the state of exceeding, the value obtained by sequentially adding the predetermined value ΔG to the control gain G is updated as a new control gain every time the timer interrupt processing of FIG. 7 is executed. Then, as shown in FIG. 12, the control gain is increased to the maximum gain G _MAX with the lapse of time, and conversely, from the state where the vehicle speed detection value V (n) or the set vehicle speed V ₁₂ is exceeded, the set vehicle speed is V ₁₂ or less. when it becomes, or when the vehicle speed detection value V (n) is a state exceeding the set vehicle speed V ₂₂ from set vehicle speed V ₂₂ following states, each time the timer interrupt process of FIG. 7 is executed, sequentially A value obtained by subtracting the predetermined value ΔG from the control gain G may be updated as a new control gain, and the control gain may be decreased to zero with the passage of time. By increasing or decreasing the gain with the passage of time in this way, the control gain is not maintained in a low state when the predictive control is started at a vehicle speed near the lower and upper boundaries of the controlled vehicle speed range, and There is an advantage that the control effect can be sufficiently exerted, and conversely, even when the preview control is stopped, the control can be gently stopped.

Further, when the detected vehicle speed V (n) is outside the controlled vehicle speed range from the state where it is within the controlled vehicle speed range, calculation of the preview control force is stopped and, as shown in FIG. Each time the timer interrupt processing shown in FIG. 7 is executed _{, the preview} control force U _pRL, U _pRR at that time may be decreased by a predetermined value ΔU. In this case, when the vehicle speed is out of the control cancellation vehicle speed range. Therefore, the preview control force is reduced, so that the preview control can be gently stopped and the preview control state can be continued to some extent.

Furthermore, in each of the above embodiments, the case where the vibration input estimation circuit 41 having an analog circuit configuration is provided to calculate the differential values x _0FL ′ and x _0FR ′ of the road surface displacement has been described, but the present invention is not limited to this. Alternatively, the microcomputer 44 can perform digital processing, and the same applies to the integration circuits 42FL to 42FR. In each of the above embodiments, the microcomputer 4
4, the differential value x _0FL 'and x _0FR' the delay time tau _F of the road surface _{displacement,} and stores while sequentially shifted into the shift register region with tau _R, the delay time tau _F, tau _R is a road surface displacement becomes zero Based on the differential values x _0FL ′ and x _0FR ′, the _preview control force U
_Although the case where _pFL to U _pRR is calculated has been described, the prediction control force U _{pFL to} U _{pRR is} not limited to this, but the process corresponding to step S7 is performed in advance based on the differential values x _0FL ′ and x _0FR ′ of the road surface displacement. Is calculated and stored together with the delay times τ _{F and} τ _R in the shift register area while being shifted, and the _preview control forces U _{pFL to} U _pRR at which the delay times τ _{F and} τ _R become zero are _stored.
May be used to calculate the total control force U _{FL to} U _RR .

Further, in each of the above embodiments, the case where the vibration input estimation circuit 41 obtains the front road surface information corresponding to the road surface displacement from the motion information of the front wheels has been described, but the present invention is not limited to this. , Front wheels 11FL and 1
A non-contact type distance sensor such as an ultrasonic distance sensor or a laser distance sensor is arranged in front of 1FR, and the front wheels 11FL, 11FR and the rear wheels 11RL, 11RL, based on the detection values of this distance sensor.
You may make it predictive-control 11RR.

Furthermore, in the above embodiment, the case where the active control of the suspension is performed only on the basis of the vertical acceleration has been described, but the present invention is not limited to this, and other lateral acceleration sensors and longitudinal accelerations can be used. It is also possible to calculate a control signal for suppressing roll, pitch, and bounce based on the acceleration detection value of a sensor or the like, and add / subtract these control signals to the pressure command values P _{FL to} P _RR to perform total control.

Furthermore, in each of the above embodiments, the case where the pressure control valves 20FL to 20RR are applied as control valves has been described, but the present invention is not limited to this, and other flow rate control type servo valves and the like are applied. It is possible. Further, in each of the above-described embodiments, the case where the pressure control valves 20FL to 20RR are applied as control valves has been described, but the present invention is not limited to this, and other flow rate control type servo valves and the like can be applied. is there.

Further, in the above embodiment, the case where the controller 30 is constituted by the microcomputer 62 has been described, but the present invention is not limited to this, and it may be constituted by combining electronic circuits such as a shift register and an arithmetic circuit. Needless to say, you can. Furthermore, in the above embodiment, the case where the working oil is used as the working fluid has been described, but the working fluid is not limited to this, and any working fluid may be applied as long as the fluid has a low compression rate.

Furthermore, in the above embodiment, the case where the active suspension is applied as the actuator has been described, but the present invention is not limited to this.
Any actuator can be applied as long as it has a configuration capable of changing the damping characteristic and the spring characteristic of the suspension such as the variable damping force type shock absorber.

[0061]

As described above, according to the suspension control device of the first aspect, the actuator disposed between the wheel to be controlled and the vehicle body using the road surface information in front of the wheel to be controlled is used. When performing preview control, the control target vehicle speed range is set, and the preview control is configured to stop outside this control target vehicle speed range.Therefore, when the vehicle speed is too high and the preview control is not in time, or when the vehicle speed is too low, detection is performed. It is possible to stop the preview control in a state where the road surface information cannot be retained, and when the vehicle runs near the boundary between the uncontrollable vehicle speed and the controllable vehicle speed, The effect that it is possible to prevent a sudden change in riding comfort is obtained.

Further, according to the suspension control device of the second aspect, since the control gain is changed according to the vehicle speed, the preview control force can be gently increased or decreased near the boundary of the vehicle speed range to be controlled. The effect of not giving a feeling of strangeness to the passenger is obtained. Further, claim 3
According to the suspension control device of the present invention, since the control gain has a hysteresis characteristic near the boundary of the controlled vehicle speed range, it is possible to prevent hunting due to vehicle speed fluctuations near this boundary and ensure a good riding comfort. You can

Further, according to the suspension control device of the fourth aspect, when the determination result of the vehicle speed determination means is outside the controlled vehicle speed range to within the controlled vehicle speed range,
Since the control gain is increased with the passage of time, it is possible to gently increase or decrease the preview control force in the vicinity of the vehicle speed range boundary where control is performed, and when increasing the control gain, control is performed after a predetermined time has elapsed. Since the gain becomes large, it is possible to obtain the effect that the normal preview control can be performed even at the vehicle speed near the boundary.

According to the suspension control device of the fifth aspect, when the determination result of the vehicle speed determination means is out of the control target vehicle speed range from the control target vehicle speed range, the preview control force at that time is set to the time. The forecast control force can be gradually decreased when the vehicle speed falls outside the control target vehicle speed range, and the preview control force gradually decreases after the vehicle speed falls outside the control target vehicle speed range. As a result, the effect that the normal preview control state can be continued to some extent is obtained.

[Brief description of drawings]

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

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

FIG. 3 is a characteristic diagram showing a relationship of control pressure with respect to a command current of a pressure control valve.

FIG. 4 is a characteristic diagram showing an output characteristic of a stroke sensor.

FIG. 5 is a characteristic diagram showing an output characteristic of a vertical acceleration sensor.

FIG. 6 is a block diagram showing an example of a controller.

FIG. 7 is a flowchart showing an example of a processing procedure of a microcomputer.

FIG. 8 is a characteristic diagram showing a relationship between a vehicle speed detection value and a preview control gain.

FIG. 9 is an explanatory diagram showing a one-wheel one-degree-of-freedom model.

FIG. 10 is a flowchart showing an example of a processing procedure of the microcomputer showing the second embodiment of the present invention.

FIG. 11 is a characteristic diagram showing a relationship between a vehicle speed detection value and a preview control gain according to the second embodiment.

FIG. 12 is a characteristic diagram showing another example of the relationship between the vehicle speed detection value and the preview control gain.

FIG. 13 is a characteristic diagram showing still another example of the relationship between the vehicle speed detection value and the preview control gain.

[Explanation of symbols]

 10 Body side member 11FL-11RR Wheel 14 Wheel side member 18FL-18RR Hydraulic cylinder 20FL-20RR Pressure control valve 22 Hydraulic source 26 Vehicle speed sensor 27FL, 27FR Stroke sensor 28FL, 28FR Vertical acceleration sensor 30 Controller 41 Vibration input estimation circuit

Front Page Continuation (72) Inventor Yosuke Akatsu 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd.

Claims (5)

[Claims] 1. An actuator which is arranged between a wheel and a vehicle body and generates a control force capable of controlling a stroke between them by a control signal, and a front road surface information detecting means for detecting road surface information in front of the wheel. And a vehicle speed detecting means for detecting a vehicle speed, and a preview control force calculated on the actuator based on a value obtained by delaying the front road surface information of the front road surface information detecting means in accordance with the vehicle speed detection value of the vehicle speed detecting means. In the suspension control device including a control means for controlling the vehicle speed, the control means determines whether the vehicle speed detection value of the vehicle speed sensor is within a control target vehicle speed range, and a determination result of the vehicle speed determination means. And a control stopping means for stopping the generation of the preview control force when the vehicle speed is outside the control target vehicle speed range. 2. The suspension control according to claim 1, wherein the control means is configured to change the control gain according to the vehicle speed detection value at the boundary position within the control target vehicle speed range based on the determination result of the vehicle speed determination means. apparatus. 3. The suspension control device according to claim 2, wherein the control means is configured to give a hysteresis characteristic to a control gain at a boundary position within a control target vehicle speed range. 4. The control means is configured to increase the control gain with the passage of time when the determination result of the vehicle speed determination means is outside the controlled vehicle speed range to within the controlled vehicle speed range. Item 3. The suspension control device according to item 1. 5. The control means, when the determination result of the vehicle speed determination means is outside the controlled vehicle speed range from within the controlled vehicle speed range, reduces the preview control force at that time with the passage of time. The suspension control device according to claim 4, which is configured.