Research On Semi-active Suspension With Robust Control

In order to improve riding comfort, specialists developed active and semi-active suspensions. The semi-active suspension can not only improve the riding performance greatly relative to the passive suspension but also can overcome the shortcomings of high cost in economic and fuel consumption coming with active suspension, which has been very hot in the automotive R&D field. This paper tries to design a new kind of semi-active suspension which should be simple to realize and can keep good performance however the parameters and the disturb change, that is to say, the new suspension must be robust.Firstly, a quarter car model of passive suspension is built. The analysis on body acceleration ,suspension dynamic displacement and tyre dynamic load of the model in amplitude-frequency properties ,roots of mean square and infinite norm were done.Secondly, semi-active quarter car model is built, robust controller is solved based on H_∞ control. Simulations are done in Matlab software, firstly the amplitude-frequency properties of passive and semi-active suspensions are compared, secondly the responses under the step excitation and white noise excitation are compared, then the robust performance when the parameters are changed are compared. The simulation results show the semi-active suspension developed can improve the riding comfort and the tyre dynamic load greatly, and the robust performance is better than the passive suspension.Thirdly , based on the above controller developed , the hardware and the software are designed. The whole system is based on a single microchip processor system. The accelerator measures the body acceleration , sends it to the amplifier to be amplified . Then the signal is sent to the A/D converter to be changed into digital data. At last the processor received the acceleration signal, then analysis it, give orders to control the actuator which is made up of a step motor and adjustable damper. In order to realize the above control process, functions of DP-51+ system are developed. The software for the system is developed in Keil C51 circumstances . When the program is finished, it is be written to the flash memory for hardware simulation. After being edited several times, the system can work in good performance.At last, the platform experiment is carried out , the excitation signal are respectively step , sine wave and the white noise. The SD380 is used to record the data. The data analysis results show: the designed controller can degrade the body vibration and the tyre dynamic load, the designing aim is reached.So we can reach the conclusions as: the controller based on H^ theory developed here has good riding comfort performance and robust performance ,and is easy to design the counterpart hardware; the controller designed reached the designing and real request.