Robust Anti-jamming Control Of ECAS Body Height Regulation System

Compared with traditional suspensions,the uniqueness of air springs gives air suspensions more performance advantages.By adjusting the body height and realizing the adaptive control of damping,air suspensions can not only effectively improve the ride comfort,handling stability and driving safety of vehicles,but also increase the fuel economy of vehicles to some certain extent.Air suspensions have become one of the research hot-spots in the automotive engineering field.Vehicle body height adjustment and accompanying body attitude control,the two key parts in the design of electronically controlled air suspensions(ECAS)control system,are very important to realize the function of ECAS system and improve the system's adaptive ability.So the corresponding research has important academic significance and engineering application values in improving the overall research level of high-performance air suspension systems of China.An ECAS bus body height regulation system is selected as the research object in this paper.According to the requirements of body height adjustment and accompanying body attitude control,in-depth researches have been conducted on control system modeling,control strategies design,interference suppression and so on.The main research contents and achievements are as follows.A mathematical model which can accurately reflect the dynamic behavior of the ECAS body height regulation system is constructed.On the premise of sufficient study about the structural composition,operating principles and subsystems' coupling behaviors of ECAS body height regulation system,a nonlinear mechanism model of the single-wheel ECAS body height regulation system is established based on the thermodynamic theory of variable mass charging and venting system and Newton's law of motion.On this basis,a corresponding nonlinear mathematical model of full-car ECAS body height regulation system is established by considering the pitch angle and roll angle of the vehicle.Finally,the two models are simplified by dimension reduction so that they can be used in the control system.The ECAS body height robust finite-time control strategy is studied.In order to achieve better convergence performance,robust stability and anti-jamming ability,the robust finite-time control is applied to the ECAS body height regulation system,which is quite different from Lyapunov's asymptotically stable control.Firstly,according to the theory that three points can determine a plan,the ECAS body height adjustment strategy is designed.Secondly,based on precise linearization theory,non-singular coordinate transformations are carried out on the nonlinear models of the ECAS body height system to achieve corresponding linear forms.Then,on the basis of linearization,the finite-time controllers are designed to make robustness control on the single wheel ECAS body height and the full-car ECAS body height respectively.Finally,simulations are carried out.The simulation results show that the ECAS body height controllers based on the finite-time theory not only achieves faster control response speed to converge to the origin,but also has better robustness and anti-jamming performance under the conditions of constant interference,sinusoidal interference and random interference.The ECAS body height robust model predictive controller is studied.There are some problems of robust finite-time controllers,such as fractional power parameters' complex adjustment and unclear physical meaning,the difficulty to deal with input constraints,and so on.In order to dissolve these problems,the model predictive controller(MPC),which has the advantages of good control effects,strong robustness and low requirements on model accuracy,is applied to the ECAS body height control system.Firstly,on the basis of the third-order linear subsystem model obtained by precise feedback linearization,the model prediction controller of the linear system is obtained by deducing the prediction model and defining performance index function.By adjusting the weighted matrix of the performance function,the system can get different response speeds and steady accuracies.Secondly,in order to improve the anti-jamming ability of the controller,a nonlinear disturbance observer is designed to estimate the random road disturbance and realize adaptive feedforward compensation.Finally,it is verified by simulation that the MPC controller with disturbance observer can effectively adjust the ECAS body height and achieve better robustness and anti-jamming ability even under the influence of uncertainties such as imprecise models and interference.Real vehicle tests are conducted to verify the control performance of the system.Based on the D2 P rapid control prototype development platform,a control performance test system is constructed on a bus equipped with ECAS.The control effects of ECAS body height robust finite-time controller and model predictive controller are tested in this platform.The test results show that the two controllers can not only adjust the body height quickly,but also solve the overcharge and overdischarge problems of air springs.At the same time,the change range of pitch angle and roll angle is controllable,and their adjustment is fast and stable.It is proved that the two controllers effectively accomplish the vehicle height adjustment and accompanying body attitude control of ECAS system.Studies of the paper have shown that the research and design of ECAS system body height adjustment and accompanying body attitude control based on the robust finite-time controller and the robust model predictive controller is effective and significant,which can obviously improve the effectiveness of the body height adjustment,stability and anti-jamming performance.At the same time,the body attitude of the car during height adjustment can be kept stable,ensuring vehicle ride comfort and handling stability.In short,the research of this paper has great significance to improve the overall performance of ECAS system.