Design And Experiment Research On The Controller Of Magnetorheological Semi-active Suspension Based On Feedback Linearization Kalman Observer

With the rapid development of social economy and the increasing improvement of people's living standards,it is difficult for passive suspension to meet consumers' demands for the ride comfort and driving safety of vehicles.The semi-active suspension is able to adjust its working mode in real time according to the driving conditions of vehicles,so as to coordinate the contradictory relationship between ride comfort and driving safety.Also,it has the advantages of low cost,low energy consumption and simple control method,which make it has broad application prospects.The control algorithm is the ‘soul' of the semi-active suspension system.Suspension state variables need to be the control inputs for the control algorithm based on state feedback while some of these signals can hardly be directly measured by sensors.In addition,the engineering application of semi-active suspension is inseparable from the development of suspension controller.Most of the current research stays in the theoretical simulation stage,lacking a complete R & D process that combines control algorithms and controller design.To this end,this paper designs a control algorithm based on state observation for semi-active suspension,and develops a suspension controller after verifying its effectiveness offline.And the main research contents are as follows:Firstly,an accurate model of 1/4 nonlinear suspension system is constructed in consideration of the geometric nonlinearity of Mc Pherson suspension and the mechanical nonlinearity of magnetorheological damper.The 1/4 model consists of the dynamic model of Mc Pherson suspension,polynomial mathematical model of magnetorheological damper,and excitation models of continuous random pavement and long-slope convex pavement.Secondly,a hybrid damping control algorithm is designed based on the mapping relationship between vehicle driving conditions and dynamic performance requirements.The advantages and disadvantages of the method for obtaining the state variables required by the control algorithm are compared and analyzed.On this basis,a feedback linearization Kalman observer(FLKO)based on differential geometry theory is designed to obtain suspension state variables.Meanwhile,the semi-active suspension system including state observation is simulated and analyzed in Matlab/Simulink.The effectiveness of the control algorithm is verified offline,which lays a theoretical foundation for the development of the suspension controller based on V-cycle mode.Then,the development of the suspension ECU using the chip STM32F103VET6 as the MCU is completed,which includes the writing of C code of the control algorithm in application layer and driving program in lower layer and the production of PCB of ECU.And a simulation system is built to conduct hardware-in-the-loop tests on the ECU based on the x PC-Target platform.The test results show that the RMS deviation of suspension dynamic performance indexes between offline simulation and hardware-in-the-loop test is within 5%,which verifies the performances of reliability,real-time and functionality of the ECU.Finally,a 1/4 suspension measurement and control platform is developed based on the front suspension of a certain car.A bench test is carried out on the magnetorheological semiactive suspension ECU.The test results show that compared with passive suspension system,the magnetorheological semi-active suspension system can significantly improve dynamic performances of vehicles,thereby verifying the effectiveness and feasibility of the designed control algorithm and the developed suspension ECU.