Hierarchical Control Strategy For Semi-active Suspension With Magnetorheological Damper Of D Class

As the development of expressway network and vehicle technology, the need of riding comfort has also increased. In the meantime, the development of vehicle and related subject make it possible. As the product of multidisciplinary, magnetorheological damper brake the limit of passive suspension, which has the characteristic of quick response, wide force range, low power dissipation and simple construct. With those characteristics, magnetorheological damper could improve vehicle riding comfort signally, which has improtant theoretical significance and engineering application value. Now as for magnetorheological damper suspension, real vehicle engineering applications, more working conditions and effectiveness are top research, and the basic of this paper.Design of magnetorheological damper with applicition peripheral application circuit and control strategy are the two key technology for magnetorheological damper suspension. Combined with the coorperation project "FAW Semi-active Suspension System Research" of FAW Technology Center, in this paper, based on the feature of semi-active suspension and magnetorheological damper, design signal integral filter circuit for acceleator, circuit driver for MR damper, electronic control unit(ECU), and develop the control algorithm to improve riding comfort and attitude of vehicle body, through offline simulation and hardware in the loop(HIL), to test the effectiveness, the main research work is as follows:(1) Hardware circuit design:a) aiming at characteristic of sprung mass and unsprung mass vertical signal, design the signal integral filter circuit for acceleration, based on bode diagram and transfer function, analysis different circuit to choose the best one, and test with HIL; b) design the circuit driver based on BUCK for magnetorheological damper, through testing with HIL, the circuit driver has the characteristic of adjustable input voltage, widely circuit output range and good linearity; c) with Freescale chip, design the ECU which used for receiving signals and generating control signals;(2) Magnetorheological damper design and its characteristic test:using MTS test equipment for damping force-stroke characteristics and the damping force-velocity characteristics, reconstruct the form of damper modle and fitting parameter with Matlab Curve Fitting Tool, building damper model and inverse model;(3) Building simulation platform and develop control algorithm:a) simulation platform which contain whole vehicle, damper and controller with carsim and Matlab/Simulink; b) develop control algorithm with the aim of improving riding comfort and vehicle body attitude, this algorithm calculate the moment according longitudinal acceleration and lateral acceleration and its direction, in order to get better distribution, in this paper, calculating each damper force with the theory of equivalent damping coefficient;(4) Test with offline simulation and hardware in the loop:a) building condition used for testing riding comfort and attitude stability in Carsim, then make offline simulation and analysis; b) based the software platform before, rebuilding software paltform which contain dSPACE RTI and Carsim RT, at the same time, connecting the signal processing circuit, circuit driver and ECU to finish the HIL platform, after writing algorithm with C code through codewarrior to ECU, finish the HIL test.