CN100482488C - Linear control of an automobile suspension - Google Patents
Linear control of an automobile suspension Download PDFInfo
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- CN100482488C CN100482488C CNB2004800263656A CN200480026365A CN100482488C CN 100482488 C CN100482488 C CN 100482488C CN B2004800263656 A CNB2004800263656 A CN B2004800263656A CN 200480026365 A CN200480026365 A CN 200480026365A CN 100482488 C CN100482488 C CN 100482488C
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Abstract
A vehicle suspension system that includes a cylinder (22), a rod (24) inserted within the cylinder, a piston (26) coupled to the rod and a piston valve (27) which has an input piston current. The suspension system further includes a base coupled to the cylinder, a base valve which (29) has an input base current, and a controller (33) coupled to the piston valve and the base valve. The controller is adapted to generate the input piston current and the input base current based on a generated virtual current.
Description
The cross reference of related application
It is the preceence of 60/502,044 U.S. Provisional Patent Application that the application requires in the application number that on September 11st, 2003 submitted to, at this in conjunction with its description as a reference.
Technical field
One embodiment of the present of invention relate to automobile suspension system.More specifically, one embodiment of the present of invention relate to the initiatively Linear Control of automobile suspension system.
Background technology
The traveling comfort of car and road handling are mainly determined by the damping force characteristics of bumper.The passive energy dissipation utensil has the fixing damping force characteristics by its designing institute decision.Yet, depend on road excitation, wish to regulate this characteristic to improve performance.Half initiatively and active suspension system can along with road profile change damper characteristics (as, by changing the throttling of one or two controllable current valve).Other advantage that active shock has is negative damping can be provided, and can produce wider power under low speed, thereby allows the performance of raising system potentially.
The theoretical linearity and the nonlinear technology of several use active suspension Control of Automobile are disclosed.These technology based on comprise lumped mass, Hookean spring and damper and be modeled as ideal force sources active shock linear physics car model and use the Linear Control strategy.Yet actual Automobile Dynamic is more complex, and active shock is not ideal force sources, but has complicated non-linear dynamic characteristic.As these results of actual hypothesis not, these prior art linear control methods are not suitable for practical application.
With non-linear control strategy, change gain scheduling and pusher, be applied to active suspension system, and only verify by analog system as linear dimensions.These controllers combine based on linearity or nonlinear physics car model and nonlinear physics damper model.These models have a large amount of parameters.The experimental identification of these model parameters is complicated (non-protruding optimization) problems.In addition, the design of above-mentioned gamma controller and adjusting are not simple and clear.In essence, owing to do not have available standard technique or Software tool, the use of nonlinear model and controller causes design very consuming time.At last, the realization of these controllers is for too complicated for the practical application in the car control system.
According to above, need to adopt the improved active suspension system of Linear Control.
Summary of the invention
One embodiment of the present of invention are vehicle suspension systems, and it comprises cylinder barrel, inserts connecting rod, piston that is connected with connecting rod in the cylinder barrel and the piston valve with input piston electric current.This suspension system also comprises and cylinder barrel bonded assembly base, the base valve with input base electric current and the controller that is connected with base valve with piston valve.Controller can produce input piston electric current and input base electric current according to the Watt current that is produced.
Description of drawings
Fig. 1 shows the passive energy dissipation device of prior art and according to the block diagram of the active shock of one embodiment of the present of invention;
Fig. 2 diagram has shown the operating range according to the active shock of one embodiment of the present of invention;
Fig. 3 shows the scheme drawing according to the bumper of one embodiment of the present of invention, and wherein bumper is connected with wheel with vehicle body;
Fig. 4 is the block diagram of signal that provides the input-output relation of one embodiment of the present of invention;
Fig. 5 diagram has shown the frequency response function of measuring and calculate according to depression of order multiinput-multioutput (" MIMO ") model (" FRF ");
Fig. 6 diagram has shown the FRF of the linear model of the property the taken advantage of probabilistic FRF that estimates and match;
Fig. 7 diagram shown the passive suspension that do not have control active suspension and adjusting, road is to the FRF of vehicle body acceleration and the FRF of tire force;
Fig. 8 is the block diagram of closed loop system;
Fig. 9 diagram has shown by the embodiment of the FRF of the linear controller of μ-comprehensively obtain and reduced order controller;
Figure 10 shows the Hankel singular value spectrum of controller and indicates the exponent number of selection.
The specific embodiment
One embodiment of the present of invention are active shock, and it comprises the controller based on the Watt current of acceleration calculation up or down of vehicle and wheel.Watt current is used to utilize the received current of better simply relatively linear technique calculating to bumper then.
An embodiment of active shock member of the present invention is designed to, and its open loop (do not have control) dynamic characteristics is suitable with the open loop dynamic characteristics of passive energy dissipation device that is similar automobile adjusting.The controller of the damping force characteristics by adjusting active shock according to road and further improve performance.
Fig. 1 illustrates the passive energy dissipation device 10 of prior art and according to the block diagram of the active shock 20 of one embodiment of the present of invention.Bumper 10 comprises cylinder barrel 12 that is filled with fluid and the connecting rod 14 that is connected with piston 16, and wherein piston 16 comprises provides the piston valve 15 of calibrating throttling.Connecting rod 14 moves into or shifts out cylinder barrel 12 caused volumes and changes, and is compensated by the fluid through base valve 17 inflows or outflow fuel accumulator 19.Produce the dumping force that acts on the piston 16 through the two pressure decay of base valve 17 and piston valve 15.
Be in operation, when connecting rod 24 moves up (positive speed), piston check valve 28 is closed and fluid is flowed through piston CVSA valve 27.Because the volume of the connecting rod 24 in cylinder barrel 22 reduces, force fluid to enter the cylinder barrel 22 through base check valve 30, thereby make the throttling of base CVSA valve 29 become inessential from fuel accumulator 31.
As shown in Figure 2, for positive speed, dumping force thereby main by the current i that is input to piston CVSA valve 27
PControl.Fig. 2 is the diagram of curves of dumping force to vibration velocity (rattle velocity).Vibration velocity is the relative velocity of connecting rod about cylinder barrel, wherein on the occasion of shifting out cylinder barrel corresponding to connecting rod.
When connecting rod 24 moved down (negative velocity), piston check valve 28 was opened, thereby makes the throttling of piston CVSA valve 27 become inessential.Because the volume of the connecting rod 24 in cylinder barrel 22 increases, so base check valve 30 is closed and fluid flows into the fuel accumulator 31 through base CVSA valve 29 from cylinder barrel 22.As shown in Figure 2, for negative velocity, dumping force thereby main by the current i that is input to base CVSA valve 29
bControl.
By comprising that further that bumper 20 is become is active with cylinder barrel 22 bonded assembly external hydraulic pump 32.The wider pressure decay that pump 32 produces through the CVSA valve, thus the dumping force scope that enlarges formed.
As described, Fig. 2 diagram has shown the operating range according to the active shock 20 of one embodiment of the present of invention.(be respectively i for the electric current that is input to base valve and piston valve
pAnd i
b) multiple combination, drawn dumping force as the function of vibration velocity.Work as i
b=i
p=i
-The time power-velocity curve of the being obtained regional dimidiation that can exert oneself.Remain on i by the electric current that will be input to piston valve
-, will be input to the electric current of base valve simultaneously from i
-Increase to i
+, and the first half of acquisition operating range.Remain on i by the electric current that will be input to base valve
-, will be input to the electric current of piston valve simultaneously from i
-Increase to i
+, and the latter half of acquisition operating range.
By only change the fact that one road current signal can cover whole enveloping surface at every turn, passed through to introduce manual signal i by embodiments of the invention
v(being called " Watt current ") and be used, wherein manual signal i
vFrom-1 to+1 changes, and corresponding with the particular combinations of following base valve and piston valve electric current:
This single Watt current has substituted the two-way primary current that is input to base valve and piston valve, as the incoming signal that is generated by controller 33.This replaces controller 33 is reduced to single output system from multiple output system, thereby has formed simpler and more direct design.
Fig. 3 shows the scheme drawing of bumper according to an embodiment of the invention, and wherein this bumper is connected with wheel 60 with vehicle body 62.From the angle of controlling Design, this is multiinput-multioutput (" MIMO ") system.The acceleration/accel a of vehicle body and wheel
bAnd a
wBe the output that can be used for the system of controller 33.The Watt current iv that is input to active shock is the input by the system of controller 33 calculating.The road displacement that is applied (road displacement) x
aAct in the system as external disturbance.
Fig. 4 is the graphic block diagram that provides the input/output relation of one embodiment of the present of invention.System dynamics is by 2 * 2 transitionmatrix G
2 * 2Expression, and controller 33 is by 1 * 2 transitionmatrix K
1 * 2Expression.
In one embodiment, can use frequency domain method to discern system dynamics of the present invention and uncertainty, this method comprises four steps: the suitable pumping signal of (1) design, (2) frequency response function of estimating system (" FRF "), (3) are discerned the parameter nominal model of these FRF and the uncertainty of (4) estimation model.
In order to discern the dynamic of this system, be input i in one embodiment
vAnd x
aDesigned pumping signal.Common Criteria in identification is to use the cooresponding pumping signal of actual excitation with system, so that the linear model of being discerned is the good approximation for the system of such excitation.
Be input to the control signal i of active shock
vEncourage by Gauss's frequency band limits white noise.Bandwidth is set to 50Hz, and it is higher than required closed-loop bandwidth fully.The selection of amplitude leyel make 2 σ boundaries of pumping signal corresponding to saturation level ± 1 to obtain good signal-to-noise.
Road displacement signal x
aEncourage by comprehensive (integrated) Gaussian white noise, its frequency spectrum is corresponding to the frequency spectrum of road at random.Measured output is the acceleration/accel a of vehicle body
bAcceleration/accel a with wheel
w
Excitation signals is applied to system simultaneously to be reached 300 seconds and samples with 1kHz.First resonance of system is the body mode of good damping, and estimates at 1.5Hz.The minimum frequency of heart that closes is roughly elected factor less than 5 as, thereby obtains the frequency resolution of 0.24Hz.Take off data is divided into 145 pieces with 4096 samples, and have 50% overlapping.Use H
1-estimation device estimation MIMO FRF matrix.Fig. 5 diagram shows the FRF (dotted line) of measurement and the FRF (solid line) that calculates according to depression of order MIMO model: from road displacement x
a(left side) and Watt current i
v(right side) is to vehicle body acceleration a
b(on) and wheel acceleration a
w(descending).
In one embodiment, adopt non-linear least square frequency domain method of identification, parameter transfer function (" TF ") matrix fitting is arrived on measured multiinput-multioutput frequency response function (MIMOFRF) matrix.Target be with simple accurate linear MIMO model fitting to measured MIMO FRF matrix.If the number of estimation model parameter (number of system's limit and transfer function zero) preferably, and can comprise and priori systematic knowledge based on the physics idea then can improve this optimized convergence.
By this system representation is served as reasons by spring and 3 lumped parameter models that mass constituted of damper bonded assembly (as shown in Figure 3), and obtain this information.For this purpose, suppose that the power of bumper and control current are proportional, thereby ignore the dynamic of active shock.These hypothesis show the linear model that has 6 rank, and it has described 3 system modes: body mode, wheel bounce mode and sleeve mode.The analysis of this lumped parameter model is also demonstrated two differentiators (at 0Hz two zero points) to be included in all 4 transfer functions.
In one embodiment, the single output of the single input in 6 rank (" SISO ") TF model is fitted to respectively on each FRF.3 complex poles of 3 system modes of expression are right, in theory should be consistent for all 4 SISO models.Yet because noise and non-linear, the limit of each model may be slightly different.In one embodiment, with these models in conjunction with the time adopted certain model reduction avoiding the bad optimization of condition in controlling Design, and reduce the complexity of controller.In order to finish this model reduction, the limit of 4 SISO TF is changed into the aviation value of the limit of the SISO model of being discerned.For the copolar point model that these are new is fitted on the measured FRF, in frequency domain, carry out the identification again at zero point.
Identification is the linear least-squares problem again, and it can not run into the problem of convergence.With by with 4 SISO models in conjunction with and the MIMO model that number obtained that do not reduce copolar point is compared, resulting depression of order MIMO model (on the least square meaning) only owes accurate slightly.
An embodiment of this system also includes the delay of 6ms, and it is by generations such as conduit under fluid pressure and motorized valves.Can lag behind and estimate above-mentioned delay according to being present in linear phase among all FRF.Can use 2 rank Pade to approach this delay is converted into a pair of complex pole and right-half plane zero point.These pole and zeros are added on the reduced-order model, thus generation parameter nominal model G as shown in Figure 4.
Nominal model G is the linear approximation to the dynamic characteristics modeling of the auto model that comprises embodiments of the invention.Sensor noise, non-linear and not the modeling high frequency dynamically caused the uncertainty of model.By 145 block datas are divided into 10 groups with 14 pieces, and the FRF matrix of a plurality of FRF that will measure and G compares, and can estimate these uncertainties.Relative mistake between these FRF is average, produce the property taken advantage of uncertainty
With
Linear model can be fitted on these uncertain estimated valves then.Fig. 6 diagram shows the FRF (solid line) of the linear model of the probabilistic FRF of the property taken advantage of (dotted line) of estimation and match.
Shown in the chart 110 of Fig. 6, with 12 rank model fittings on the property the taken advantage of uncertainty of vehicle body acceleration output.This uncertainty 0.5 and 10Hz between far below 100% (0dB).At the zero point of 12Hz place slight fading, make that uncertainty reaches peak value in this frequency relatively among the model G.
Shown in the chart 120 of Fig. 6, with 4 rank model fittings on the property the taken advantage of uncertainty of wheel acceleration output.This uncertainty 1 and 15Hz between be lower than 100% (0dB).
An embodiment of controller 33 is linear controllers, decay vehicle body acceleration near its frequency field body mode (1.5Hz), and in other frequency domain, do not amplify vehicle body acceleration or change tire force.The improvement that this has considered traveling comfort and has controlled characteristic.Can obtain robust performance by the uncertainty of considering estimated model.The standard passive energy dissipation device of suspension system adjusting for this reason can be used as reference, as shown in Figure 7, its diagram show the passive suspension (long and short dash line) that do not have control active suspension (solid line) and adjusting, road is to the FRF (chart 130) of vehicle body acceleration and the FRF (chart 140) of tire force.
The generalized object P that uses in the representative type Robust Controller Design comprises 2 class input and output: outside input and output, and controller input and output.The expected frequency composition of the frequency content of external input signal and external output signal is expressed by the frequency domain weighting function, so that expected performance can be expressed as the boundary of the H ∞ norm of augmentation object.
One embodiment of the present of invention have an outside input, promptly as the simulated roadway displacement x of not measuring disturbance variable
aThe representative type frequency content of road at random is comprehensive white noise, and it is by weighting function W
rSimulation.It has the lag compensator characteristic, has the slope of 20dB/decade in care frequency field, and has zero slope in low-frequency range and high band, sets forth necessary condition with the problem that satisfies perfect state-Space H ∞ controlling Design.
Use weighting function W
uWith the first external output signal z
uBe defined as weighting control input i
vWith W
uBe set to 1, show for all frequencies, 2 norms of control input all should be less than 1, thereby avoids control current i
vSupersaturation.
Use weighting function W
pWith the second external output signal z
pBe defined as weighting vehicle body acceleration signal a
bW
pBe bandpass filter, have near the cutoff frequency body mode resonance, make from W
rTo z
pSystem's amplitude greater than the amplitude in the frequency field of this resonance.This shows that controller should decay at the vehicle body acceleration of body mode resonance.The exact location of the cutoff frequency of this bandpass filter weight is the adjustment data in one embodiment of the present of invention.Increase the desired width of the frequency field of decay, infeasible up to this controlling Design problem.
Also by the property taken advantage of output uncertainty models
With
To system's augmentation.This has formed uncertain input
With
With output
With
By with weights W
r, W
u, W
p,
With
Absorb among the model G, obtain generalized object P, thereby produce block diagram as shown in Figure 8.
If the closed loop system of controller K shown in can stability diagram 8, it can obtain robust performance so.Because based on the structure singular value of closed loop system, so μ-Comprehensive Control design framework can be considered the structure of Δ-piece.Controller synthesis is based on the DK-method of iteration in one embodiment, and wherein the D-scaling function of alternation is suitable for approaching structure singular value (D-step), and designs H ∞ controller (K-step).
Fig. 9 diagram shows an embodiment (solid line) and the reduced order controller (dotted line) by μ-comprehensive controller 33 that obtains.The input of controller is the vehicle body acceleration a that measures
b(left side) and wheel acceleration a
w(right side), output are the Watt current i that is input to active shock
vThe exponent number of controller is 60, and it adds the exponent number of D yardstick (scalings) for the exponent number of augmentation object.
In one embodiment, the high exponent number of controller has several shortcomings of following summary:
Value conditions defective mode space matrix
The real-time processor overload
Excessive internal memory uses
So, in one embodiment, approach the exponent number that reduces controller by optimum Hankel.Figure 10 shows the Hankel singular value spectrum of controller and indicates selected exponent number: 14.Relatively the demonstrating of the FRF of depression of order and initial controller in Fig. 9, the higher frequency band more than 20Hz only has less deviation, and therefore there is not the deterioration of closed-loop characteristic in expection.
As disclosed, the controller that embodiment produced with active suspension of the present invention of linear Robust Controller Design technology, compare with the traveling comfort that is obtained by the passive energy dissipation device of regulating and can significantly improve traveling comfort: the decay near the vehicle body acceleration the body mode frequency has increased by 50%.Conversion from actual base valve electric current and piston valve electric current to the single channel Watt current makes alternative MIMO nonlinear Control design and uses SISO Linear Control technology.The handling of the passive energy dissipation device of handling that is obtained and adjusting is suitable.The peak value of tire force does not significantly increase.
This paper specifically illustrates and/or has illustrated several embodiments of the present invention.The boundary that it should be understood, however, that above explanation and appended claim has contained, and does not depart from the remodeling of the present invention and the variation of essence of the present invention and desired extent.
Claims (14)
1. vehicle suspension system, it comprises:
Cylinder barrel;
Insert the connecting rod in the described cylinder barrel;
The piston that is connected with described connecting rod;
With the piston valve that described piston is connected, wherein said piston valve has the input piston current i
p
The base that is connected with described cylinder barrel;
With the base valve that described base is connected, wherein said base valve has input base current i
bAnd
Controller, it is connected with described base valve with described piston valve, and described controller can be according to the Watt current i that is produced
vProduce described input piston electric current and described input base electric current,
Wherein produce described input piston electric current and described input base electric current by described Watt current according to following equation:
And i wherein
-Corresponding to the electric current that is associated with the minimum throttle position of described piston and base valve, i
+Corresponding to the electric current that is associated with the maximum throttle position of described piston and base valve.
2. vehicle suspension system as claimed in claim 1, wherein said piston valve and described base valve are the continuous variable semi-active valves of controllable current.
3. vehicle suspension system as claimed in claim 1, it also comprises the pump that is connected with described cylinder barrel.
4. vehicle suspension system as claimed in claim 1, its also comprise with described piston bonded assembly piston check valve and with described base bonded assembly base check valve.
5. vehicle suspension system as claimed in claim 1, wherein the normal acceleration according to vehicle and wheel produces described Watt current.
6. vehicle suspension system as claimed in claim 1 wherein produces described Watt current according to linear model.
7. the method for the active shock of a control vehicle, described bumper has controllable current piston valve and controllable current base valve, and described method comprises:
Receive the normal acceleration of described vehicle;
According to described acceleration calculation Watt current; With
According to described Watt current i
vCalculate the piston valve current i
pWith the base valve current i
b,
Wherein calculate described piston valve electric current and described base valve electric current according to following equation:
And i wherein
-Corresponding to the electric current that is associated with the minimum throttle position of described piston and base valve, i
+Corresponding to the electric current that is associated with the maximum throttle position of described piston and base valve.
8. method as claimed in claim 7 is wherein calculated described Watt current according to linear model.
9. method as claimed in claim 7 is wherein calculated described Watt current by μ-comprehensive Design controller.
10. method as claimed in claim 7, described controller also can be calculated described Watt current according to vertical wheel acceleration.
11. the controller of the active shock of a control vehicle, described bumper have controllable current piston valve and controllable current base valve, described controller is suitable for:
Receive the normal acceleration of described vehicle;
According to described acceleration calculation Watt current; With
According to described Watt current i
vCalculate the piston valve current i
pWith the base valve current i
b,
Wherein calculate described piston valve electric current and described base valve electric current according to following equation:
And i wherein
-Corresponding to the electric current that is associated with the minimum throttle position of described piston and base valve, i
+Corresponding to the electric current that is associated with the maximum throttle position of described piston and base valve.
12. controller as claimed in claim 11 wherein calculates described Watt current according to linear model.
13. controller as claimed in claim 11, it comprises μ-comprehensive Design.
14. controller as claimed in claim 11, described controller also can calculate described Watt current according to vertical wheel acceleration.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US50204403P | 2003-09-11 | 2003-09-11 | |
| US60/502,044 | 2003-09-11 | ||
| US10/861,373 | 2004-06-07 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1849226A CN1849226A (en) | 2006-10-18 |
| CN100482488C true CN100482488C (en) | 2009-04-29 |
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ID=37078391
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004800263656A Expired - Fee Related CN100482488C (en) | 2003-09-11 | 2004-09-09 | Linear control of an automobile suspension |
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| CN (1) | CN100482488C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6339919B2 (en) * | 2014-10-06 | 2018-06-06 | Ｋｙｂ株式会社 | Shock absorber |
| CN106286677B (en) * | 2016-09-30 | 2019-02-01 | 北京汽车股份有限公司 | Vehicle shock absorber and automobile |
| CN111457046B (en) * | 2020-04-26 | 2021-09-10 | 江苏大学 | Passive realization device for acceleration control |
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| CN1849226A (en) | 2006-10-18 |
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