Research On Robust Control Of Magnetorheological Suspension For All Terrain Vehicle

All-terrain vehicle(ATV)is a special vehicle which designed for harsh environment and region.It has the characteristic of fast,maneuverability and flexible,and plays an important role in personnel transportation,equipment and logistics material support.Independent suspension structure with parallel spring and damper is mostly adopted in ATV.Due to the fixed parameters,this suspension cannot adapt to the changes of load and driving conditions,and the maneuvering performance and maximum off-road speed cannot meet the operational requirement.The intelligent suspension system based on magnetorheological material has the advantages of continuous and controllable damping,fast response and low energy consumption,and it can adaptively reduce the vibration transmitted from the road to the body/human vibration according to the changes of complex road,so it become an important direction of the development of ATV suspension system.The research on the MR suspension control system of ATV is at the initial stage,and there are still some problems to be solved in practical application,such as information acquisition,system parameter uncertainty and system delay.Firstly,the attitude identification of ATV is difficult because of the complex driving condition,and the accuracy of identification is affect by the noisy and abnormal value of signal.Secondly is the problem of the parameter uncertainty in the system model.The loading mass of ATV is related to the travel task,and the damping coefficient of MR damper is varied with the travel speed.Thirdly,there is time delay in the control system caused by actuator response,which will reduce or even worsen the control performance of the design controller.This paper focuses on the above three problems and the main contents are as follows:(1)The nonlinear model of the whole vehicle based on vehicle dynamics and the nonlinear model of the Carsim vehicle based on real vehicle test data are established respectively.The linearization conditions of the nonlinear model of the whole vehicle are determined according to the range of attitude changes of the ATV which driving on the off-road road.Based on the correlation analysis method,the influence of linear error on the linearized model is studied.The uncertain parameters and their ranges of the linear model of MR suspension of ATV are discussed.(2)In view of the phenomenon of high coupling degree of different motion modes of ATV which driving on off-road,a multi-sensor information fusion technology is proposed to realize the identification of driving conditions.Various characteristic sensors and their characteristic values associated with driving conditions are determined by the improved distance evaluation method,and the identification rules are designed.In view of the uncertain factors of sensor signals such as noise and outliers,the identification results based on characteristic values are fused by D-S synthesis rule,and the identification results were obtained based on the decision rules of feasible interval.On this basis,the identification method based on the feature layer fusion and the identification method based on the D-S evidence theory are compared and analyzed using the Carsim vehicle simulation platform(3)For the parameter uncertainty problem of viscosity coefficient of MR damper and loading mass,the norm bounded uncertain models is used to model the uncertainty parameter,and set the time-domain hard constraints and suspension system performance index as goal,a robust controller based on the Lyapunov stability theory and linear matrix inequality(LMI)technique is designed to guarantee system performance is less than the given value in the case of unknown bounded parameter perturbation.At the same time,a state observer based on filter is designed to estimate the state of the controller,which solves the problem of the observation accuracy is affected by the uncertainty model parameters and unknown disturbance.Finally,the control effect of the proposed algorithm is verified by Matlab/Simulink simulation.(4)Consider of the actuator delay,the MR suspension control system of ATV is equivalent to a time-delay system with bounded uncertain parameters.In order to reduce the conservatism of the controller,the time-delay dependent stability condition of the uncertain system with time delay is obtained based on the stability theory of Lyapunov-krasovskii,and the control gain of the controller is obtained by using the linear matrix inequality technology.At the same time,a state observer based on filter is designed for the uncertain system with time delay,the state can be accurately e estimated with all allowable uncertain parameters and time delay.Finally,the control effect of the proposed algorithm is verified by Matlab/Simulink simulation.(5)The hardware control system of the MR suspension of ATV is built,and the software code of the robust time-delay controller is written.Then,the real vehicle road control experiment with sprung mass parameter uncertainty and time delay of MR damper are carried out to verify the real-time control effect of the robust time-delay algorithm proposed in this paper.The research of this paper has important theoretical guiding significance and practical reference value for promoting the application of magnetorheological technology in military vehicles.