Overloaded Flatbed Truck Steering System Of Fuzzy Pid Control Study

Heavy platform truck is a special kind of vehicles for transiting heavy equipment and components;It is widely used in the over loading area,such as conveying part of big ship,industrial mainframe and etc.As an important part of the heavy platform truck,the cyclical wheel group hydraulic system plays a key role in the aspect of carrying performance. The cyclical performance has a direct influence on flexibility, stability and economy. During the course of carrying and veering,the differernt bridges and wheel groups should cooperate with each other, and respond frequently.Firstly,based on the Principle of Ackeman Theory, the thesis discussed the cyclical performance of the heavy platform truck, described the relationship between the steering mode and turning, and built the mathematical model on the deflection angle of each cyclical wheel group under the respective steering mode. The deflection angle of each cyclical wheel group fulfilling the mathematical model is the basis of cooperation in steering of the heavy platform truck.Secondly, based on the method of the transfer function ,the dynamic equation of the heavy platform truck's steering system, which was a kind of proportional valve-controlling-cylinder hydraulic system ,was established.The controlling system adopted the fuzzy-PID strategy, the relevant controller was designed,and the simulation model of the steering system founded on the simulink function in the MATLAB was built. The results indicate that the steering wheel group under the fuzzy-PID controlling can respond quickly without the overshoot.Lastly, the experimental platform of proportional valve-controlling-cylinder hydraulic was built, the data collection and the controlling of the location of the hydraulic cylcinder was made real based on the process of VB6.0.The results of simulation and experiment indicate that fuzzy-PID strategy can improve the temporal response performance of steering wheel group ,compares with conventional PID strategy.And it have important theoretical significance and practical application value.