CN105172511A - Automobile suspension shock absorber control system and method - Google Patents

Abstract

The invention discloses an automobile suspension shock absorber control system and method. The automobile suspension shock absorber control system comprises an automobile body vertical vibration acceleration sensor, a state observer, a controller and a magnetorheological shock absorber. The state observer can recognize and predict the running state of an automobile body and the running road condition only according to an automobile body vertical vibration acceleration sensor signal, and other on-board sensors are not needed. The controller adjusts the current value of an electromagnetic coil in a piston rod of the magnetorheological shock absorber in real time according to an estimated result of the state observer, and then real-time control over the performance of the magnetorheological shock absorber is achieved. The automobile suspension shock absorber control system has good working conditions all the time under various automobile conditions and road conditions, is suitable for various road and non-road vehicles, and is especially suitable for the high-end passenger automobile and new energy automobile market.

Description

A kind of shock absorber of automobile suspension control system and method

Technical field

The invention belongs to vehicle shock absorber technical field, be specifically related to the design of a kind of shock absorber of automobile suspension control system and method.

Background technology

Vehicle shock absorber is arranged between vehicle frame and vehicle bridge, and concussion when rebounding after being mainly used to suppress spring shock-absorbing and the impact from road surface, make vehicle return to rapidly normal motoring condition.

Liquid in magneto-rheological vibration damper piston is the soft grain suspending fluid of a kind of magnetic, utilize the change in the magnetic field of magnet coil in piston rod to control its rheological behavior, thus the dumping force that generation is swift in response, controllability is strong, the features such as dumping force is adjustable although magneto-rheological vibration damper has, compact conformation, but need outside to provide energy, in addition, the energy of vibration of vehicle dissipates with the form of heat by this shock absorber, and this does not meet energy-conservation theme.Realize the optimal control of magneto-rheological vibration damper, control system just needs the running state of grasp automobile in real time and travels traffic information, just needs more onboard sensor, which also limits the development of shock absorber.

In order to reduce onboard sensor quantity, improving riding comfort and the road-holding property of vehicle, just needing to design a kind of the shock absorber control system and the method that are easy to realization.

Summary of the invention

The object of the invention is the problem being difficult to realize closed loop control in order to solve magneto-rheological vibration damper in prior art, proposing a kind of shock absorber of automobile suspension control system and method.

Technical scheme of the present invention is: a kind of shock absorber of automobile suspension control system, comprises vehicle body Vertical Acceleration sensor, state observer, controller and magneto-rheological vibration damper; Controller, magneto-rheological vibration damper, vehicle body Vertical Acceleration sensor connect in turn, and vehicle body Vertical Acceleration sensor, controller, magneto-rheological vibration damper are connected with state observer respectively.

Preferably, vehicle body Vertical Acceleration sensor is used for the vertical vibration state of Real-time Collection automobile and sends it to state observer.

Preferably, the state observer current value be used in the automobile vertical vibration state that collects according to vehicle body Vertical Acceleration sensor and magneto-rheological vibration damper piston rod in magnet coil calculates the best guess value of motoring condition, and sends it to controller.

Preferably, the best guess value that controller is used for the motoring condition obtained according to state observer calculates the optimal current value of magnet coil in magneto-rheological vibration damper piston rod, and controls magnet coil in magneto-rheological vibration damper piston rod in real time and work with optimal current value.

Present invention also offers a kind of shock absorber of automobile suspension control method, comprise the following steps:

S1, system obtain calculating parameter;

S2, computing system continuous print equation of state;

The equation of state of S3, computing system discretization;

The best guess value of S4, calculating motoring condition;

S5, solution Buddhist nun Riccati equation;

S6, calculating export the optimal current value of magnet coil in magneto-rheological vibration damper piston rod.

Further, the calculating parameter in step S1 comprises equivalent mass, equivalent damping, the equivalent stiffness of piezoelectric patches, shock absorber screw spring rigidity, tire equivalent stiffness, the sprung weight of automobile, unsprung weight, the apparent viscosity (AV) of magnetic flow liquid, the piston effective length of magneto-rheological vibration damper, cylinder diameter, the piston diameter of axle, the gap between piston and cylinder body, coefficient of correction, the magnetorheological fluid damp coefficient of performance, system noise and observation noise.

Further, step S4 comprises step by step following:

S41, init state observer;

S42, calculation error covariance and state thereof;

S43, calculating kalman gain;

S44, calculating export the best guess value of motoring condition.

The invention has the beneficial effects as follows: shock absorber of automobile suspension control system provided by the invention identifies according to onboard sensor signal the running state of automobile and traveling road conditions and predicts, real-time closed-loop regulates the performance of magneto-rheological vibration damper, make magneto-rheological vibration damper under various vehicle condition and road conditions, have optimum service conditions, be applicable to different kinds of roads and off-the-road vehicle, be particularly useful for high-end manned vehicle and new-energy automobile market.

Accompanying drawing explanation

Fig. 1 is shock absorber of automobile suspension control system block diagram provided by the invention.

Fig. 2 is shock absorber of automobile suspension control method diagram of circuit provided by the invention.

Fig. 3 is the controlled object equivalent model sketch of shock absorber of automobile suspension control system provided by the invention.

Fig. 4 is the diagram of circuit step by step of step S4 in shock absorber of automobile suspension control method provided by the invention.

Detailed description of the invention

Below in conjunction with accompanying drawing, embodiments of the invention are further described.

The invention provides a kind of shock absorber of automobile suspension control system, as shown in Figure 1, comprise vehicle body Vertical Acceleration sensor, state observer, controller and magneto-rheological vibration damper; Controller, magneto-rheological vibration damper, vehicle body Vertical Acceleration sensor connect in turn, and vehicle body Vertical Acceleration sensor, controller, magneto-rheological vibration damper are connected with state observer respectively.

Wherein, vehicle body Vertical Acceleration sensor is used for the vertical vibration state y of Real-time Collection automobile and sends it to state observer.

State observer is used for the current value I in the automobile vertical vibration state y that collects according to vehicle body Vertical Acceleration sensor and magneto-rheological vibration damper piston rod in magnet coil ₀calculate the best guess value of motoring condition , and send it to controller.State observer only can identify and predict the running state of automobile and traveling road conditions according to vehicle body Vertical Acceleration sensor signal, and does not need other onboard sensor.

Controller is used for the best guess value of the motoring condition obtained according to state observer calculate the optimal current value I of magnet coil in magneto-rheological vibration damper piston rod, and in real-time control magneto-rheological vibration damper piston rod, magnet coil works with optimal current value.Externally-applied magnetic field is produced after magnet coil energising, under the influence of a magnetic field, the damping force characteristics of the magnetic flow liquid in magneto-rheological vibration damper changes, thus the dumping force that generation is swift in response, controllability is strong, to guarantee there is good service conditions under various vehicle condition and road conditions.

Present invention also offers a kind of shock absorber of automobile suspension control method, as shown in Figure 2, comprise the following steps:

S1, system obtain calculating parameter.

As shown in Figure 3, calculating parameter comprises equivalent mass m, equivalent damping η, the equivalent stiffness k of the piezoelectric patches in Fig. 3 to the controlled object equivalent model sketch of a kind of shock absorber of automobile suspension control system provided by the invention here ₁, shock absorber screw spring rigidity k ₂, tire equivalent stiffness k ₃, the sprung weight M of automobile ₁, unsprung weight M ₂.In addition, calculating parameter also comprises the apparent viscosity (AV) c of magnetic flow liquid, the piston effective length L of magneto-rheological vibration damper, cylinder diameter d ₁, piston diameter of axle d ₂, the gap h between piston and cylinder body, adjusted coefficient K ₀, magnetorheological fluid damp coefficient of performance K _i, system noise Q ^*with observation noise R ^*.

Wherein, system refers to a kind of shock absorber of automobile suspension control system provided by the invention.

S2, computing system continuous print equation of state.

According to the controlled object equivalent model of shock absorber of automobile suspension control system as shown in Figure 3, respectively with mass m, M ₁, M ₂for force analysis object, set up the oscillatory differential equation of system according to Newton's second law:

$m(\stackrel{\·\·}{u_1}+\stackrel{\·\·}{u_2}+\stackrel{\·\·}{u_3}+\stackrel{\·\·}{Y})+\mathrm{\η}\stackrel{\·}{u_1}+k_1{u}_1=0$

$M_1\left(\stackrel{\·\·}{u_2}+\stackrel{\·\·}{u_3}+\stackrel{\·\·}{Y}\right)+\frac{12{\mathrm{cLA}}_p^2}{{\mathrm{\πd}}_1{h}^3}\stackrel{\·}{u_2}+\frac{3K_0{K}_I{\mathrm{LA}}_p}{h}I\mathrm{sgn}\left(\stackrel{\·}{u_2}\right)+k_2{u}_2-\mathrm{\η}\stackrel{\·}{u_1}-k_1{u}_1=0---\left(1\right)$

$M_2\left(\stackrel{\·\·}{u_3}+\stackrel{\·\·}{Y}\right)+k_3{u}_3-\frac{12{\mathrm{cLA}}_p^2}{{\mathrm{\πd}}_1{h}^3}\stackrel{\·}{u_2}-\frac{3K_0{K}_I{\mathrm{LA}}_p}{h}I\mathrm{sgn}\left(\stackrel{\·}{u_2}\right)=0$

U in formula ₁, u ₂, u ₃, Y represents the deflection of the maximum defluxion of piezoelectric patches, shock absorber, the vertical deflection of tire, road roughness displacement input respectively; C is the apparent viscosity (AV) of magnetic flow liquid, and L is the piston effective length of magneto-rheological vibration damper, d ₁for cylinder diameter, d ₂for the piston diameter of axle, for the payload space of piston, h is the gap between piston and cylinder body, I be flow through magnet coil in magneto-rheological vibration damper piston rod electric current, K ₀for coefficient of correction, span is [0.8,1], K _ifor the magnetorheological fluid damp coefficient of performance.

State variable and the output variable of getting system are respectively $x={\left[\begin{array}{cccccc}{u}_1& \stackrel{\·}{u_1}& u_2& \stackrel{\·}{u_2}& u_3& \stackrel{\·}{u_3}\end{array}\right]}^T,y=\stackrel{\·\·}{u_2}+\stackrel{\·\·}{Y},$ Then can obtain system continuous print equation of state by formula (1) is:

$\stackrel{\·}{x}=Ax+BI+{\left[\begin{array}{cccccc}0& 0& 0& 0& 0& -\stackrel{\·\·}{Y}\end{array}\right]}^T,y=Cx+DI+\stackrel{\·\·}{Y}---\left(2\right)$

Wherein:

$A=\left[\begin{array}{cccccc}0& 1& 0& 0& 0& 0\\ -k_1(\frac{1}{m}+\frac{1}{M_1})& -\mathrm{\η}(\frac{1}{m}+\frac{1}{M_1})& \frac{k_2}{M_1}& \frac{12{\mathrm{cLA}}_p^2}{{\mathrm{\πM}}_1{d}_1{h}^3}& 0& 0\\ 0& 0& 0& 1& 0& 0\\ \frac{k_1}{M_1}& \frac{\mathrm{\η}}{M_1}& -\frac{k_2}{M_1}& -\frac{24{\mathrm{cLA}}_p^2}{{\mathrm{\πM}}_1{d}_1{h}^3}& \frac{k_3}{M_2}& 0\\ 0& 0& 0& 0& 0& 1\\ 0& 0& 0& \frac{12{\mathrm{cLA}}_p^2}{{\mathrm{\πM}}_2{d}_1{h}^3}& -\frac{k_3}{M_2}& 0\end{array}\right],B=K\left[\begin{array}{c}0\\ \frac{1}{M_1}\\ 0\\ -\frac{2}{M_1}\\ 0\\ \frac{1}{M_2}\end{array}\right]$

$C=\left[\begin{array}{cccccc}\frac{k_1}{M_1}& \frac{\mathrm{\η}}{M_1}& -\frac{k_2}{M_1}& -\frac{24{\mathrm{cLA}}_p^2}{{\mathrm{\πM}}_1{d}_1{h}^3}& \frac{k_3}{M_2}& 0\end{array}\right],D=-\frac{2K}{M_1},K=\frac{3K_0{K}_I{\mathrm{LA}}_{p}sgn\left(\stackrel{\·}{u_2}\right)}{h}$

The equation of state of S3, computing system discretization.

Kalman filtering is that a kind of equation of state of system that utilizes carries out the algorithm of best guess to state of the system, this algorithm take minimum mean square error as best estimate criterion, utilize the observed value of the estimated valve of previous moment and current time to upgrade the estimation to state variable, this algorithm makes to needing signal to be processed the estimation meeting minimum mean square error according to the system equation set up and observational equation.Because observed data comprises the impact of the Noise and Interference in system, so best guess also can regard filtering as.Design is estimated based on the running state of state observer to automobile of Kalman filtering, the quantity that can reduce onboard sensor, the robust performance improving control system, reduces costs.

The equation of state that can be obtained system discretization by formula (2) is:

x _k＝Fx _k-1+GI _k-1+w _k-1,y _k＝Cx _k+DI _k+v _k

(3)

F＝E+AT _s,G＝BT _s

Wherein x _kfor system kth (k=0,1,2 ...) state value in moment, I _kfor system kth (k=0,1,2 ...) moment flows through the electric current of magneto-rheological vibration damper magnet coil, T _sfor the sampling time, E is 6 rank identity matrixs.

The best guess value of S4, calculating motoring condition.

As shown in Figure 4, this step comprises step by step following:

S41, init state observer:

${\hat{x}}_0^{+}=E\left(x_0\right),P_0^{+}=E\left\{({\hat{x}}_0^{+}-x_0){({\hat{x}}_0^{+}-x_0)}^T\right\}---\left(4\right)$

X in formula ₀for motoring condition initial value initial value.

S42, calculation error covariance and state thereof:

$\begin{array}{c}{P}_k^{-}={\mathrm{FP}}_{k-1}^{+}{F}^T+Q_{k-1}^{*}\\ P_k^{+}=(E-K_{k}C)P_k^{-}\end{array}---\left(5\right)$

S43, calculating kalman gain:

$K_k=P_k^{-}{C}^T{({\mathrm{CP}}_k^{-}{C}^T+R_k^{*})}^{-1}---\left(6\right)$

S44, calculating export the best guess value of motoring condition:

${\hat{x}}_k^{+}={\hat{x}}_k^{-}+K_k(y_k-C{\hat{x}}_k^{-}-{\mathrm{DI}}_k)\mathrm{---}\left(7\right)$

In formula for kth (k=0,1,2 ...) moment time the updated value of motoring condition.

Then be kth (k=0,1,2 ...) moment time the best guess value of motoring condition.

S5, solution Buddhist nun Riccati equation:

PA+A ^TP-PBR ^-1B ^TP+Q＝0(8)

Wherein weight matrix Q and R is symmetric matrix, and Q is positive semidefinite matrix, and R is positive definite matrix.

Obtain unique steady-state solution P of Buddhist nun's Riccati equation thus.

S6, calculating export the optimal current value I of magnet coil in magneto-rheological vibration damper piston rod:

$I=-R^{-1}{B}^{T}P\hat{x}---\left(9\right)$

In formula be kth (k=0,1,2 ...) moment time the best guess value of motoring condition.

And then produce externally-applied magnetic field after magnet coil energising, under the influence of a magnetic field, the damping force characteristics of the magnetic flow liquid in magneto-rheological vibration damper changes, thus the dumping force that generation is swift in response, controllability is strong, to guarantee there is good service conditions under various vehicle condition and road conditions.

Those of ordinary skill in the art will appreciate that, embodiment described here is to help reader understanding's principle of the present invention, should be understood to that protection scope of the present invention is not limited to so special statement and embodiment.Those of ordinary skill in the art can make various other various concrete distortion and combination of not departing from essence of the present invention according to these technology enlightenment disclosed by the invention, and these distortion and combination are still in protection scope of the present invention.

Claims (7)

1. a shock absorber of automobile suspension control system, is characterized in that, comprises vehicle body Vertical Acceleration sensor, state observer, controller and magneto-rheological vibration damper; Described controller, magneto-rheological vibration damper, vehicle body Vertical Acceleration sensor connect in turn; Described vehicle body Vertical Acceleration sensor, controller, magneto-rheological vibration damper are connected with state observer respectively.

2. shock absorber of automobile suspension control system according to claim 1, is characterized in that, described vehicle body Vertical Acceleration sensor is used for the vertical vibration state of Real-time Collection automobile and sends it to state observer.

3. shock absorber of automobile suspension control system according to claim 2, it is characterized in that, the described state observer current value be used in the automobile vertical vibration state that collects according to vehicle body Vertical Acceleration sensor and magneto-rheological vibration damper piston rod in magnet coil calculates the best guess value of motoring condition, and sends it to controller.

4. shock absorber of automobile suspension control system according to claim 3, it is characterized in that, the best guess value that described controller is used for the motoring condition obtained according to state observer calculates the optimal current value of magnet coil in magneto-rheological vibration damper piston rod, and controls magnet coil in magneto-rheological vibration damper piston rod in real time and work with optimal current value.

5. a shock absorber of automobile suspension control method, is characterized in that, comprises the following steps:

S1, system obtain calculating parameter;

S2, computing system continuous print equation of state;

The equation of state of S3, computing system discretization;

The best guess value of S4, calculating motoring condition;

S5, solution Buddhist nun Riccati equation;

S6, calculating export the optimal current value of magnet coil in magneto-rheological vibration damper piston rod.

6. shock absorber of automobile suspension control method according to claim 5, it is characterized in that, calculating parameter in described step S1 comprises equivalent mass, equivalent damping, the equivalent stiffness of piezoelectric patches, shock absorber screw spring rigidity, tire equivalent stiffness, the sprung weight of automobile, unsprung weight, the apparent viscosity (AV) of magnetic flow liquid, the piston effective length of magneto-rheological vibration damper, cylinder diameter, the piston diameter of axle, gap between piston and cylinder body, coefficient of correction, the magnetorheological fluid damp coefficient of performance, system noise and observation noise.

7. shock absorber of automobile suspension control method according to claim 5, is characterized in that, described step S4 comprises step by step following:

S41, init state observer;

S42, calculation error covariance and state thereof;

S43, calculating kalman gain;

S44, calculating export the best guess value of motoring condition.