The Automotive Semi-active Suspension State Monitoring System Design

With the development of automobile technology and the improvement of people’s living quality, people pay more and more attention to the parameters including driving comfort and stability of the car. The vehicle suspension is the force transmission device between the body and wheels, which affects driving comfort and handing stability of vehicles. The passive suspension parameters cannot be changed when it was produced. The vehicle active suspension damping controller can be adjusted automatically according to the road condition, which however is complex and expensive. Compared with the following suspensions mentioned, the damper of the semt-active suspension which based on the passive suspension is controlled. In the meanwhile, the performance of the semi-active suspension is closed to that of the active suspension. So the semi-active suspension has become the focus in the industry of automobile suspended frame.The heaven acceleration of the center of gravity of the body, the pitching acceleration, the roll angule acceleration, the dynamic deflection of suspension system and the vehicle dynamic tyre loads are the important parameters which affecting driving comfort and handing stability. The vehicle suspension performance depend on the accurately state parameters of automobile suspension. However the sensors boarded in the vehicle exist drift and error accumulation in the practical application environment. So there is bigger measurement in the measurement of vehicle suspension state parameters. In order to measure parameters of the vehicle suspension accurately, the vehicle state estimation algorithm play a great role in estimating the parameters of the vehicle suspension.This paper firstly introduces the theory and working principle which include coordinate system and state parameters of the vehicle suspension. The paper mainly introduces the system state forecast theory and the system state decoding theory. Microprocessor estimate the parameters of the vehicle suspension by using the algorithm. The state variables and observed variables are selected according to the distribution of the sensors in the vehicle. Signature the state equation and measurement equation of the automobile suspension system. Extended kalman filtering algorithm is used to estimate the parameters of the automobile suspension state. The simulation results verify the effectiveness of the proposed algorithm which is used to estimate the parameters of the vehicle suspension state. Secondly, the paper introduces the hardware and software design of the vehicle semi-active suspension state monitoring system. The paper respectively introduces the every modules of the hardware platform.The content of the software analyses the software realization of state monitoring system for the vehicle semi active suspension. In order to test the feasibility and reliability of the suspension state monitoring system, this paper has set up a embedded real-time testing platform and discussed the principle of a portable C code generated by the tool of Simulink/RTW in the platform of the windows. Finally, the paper set up automotive semi-active suspension state monitoring experiment system. And then, the paper introduces the realization of the vehicle suspension state estimation and calculation process in detail. In the meanwhile, the problems which include the libraries, cross compile tools as well as matching platform file format of the code migration and debugging are solved. Cross-platform transplantation and operation of the code is implemented.Results of the system test show that automotive semi-active suspension state monitoring system which consists of eight accelerometers and an inertial measurement unit(IMU) focus on OK6410 microprocessor and Linux 3.01 real-time operating system. The system can realize real-time calculating state data of vehicle suspension, which play a great role in improving the precision control of vehicle semi-active suspension damper.