Research On Adaptive Control Strategy For Steering Gear System

Steering system mainly applies in the aerospace, military and other special occasions as high-precision position servo system. For steering gear control system usually with nonlinear and time-varying load characteristics and the precise dynamic model is difficult to establish, so, fuzzy adaptive control strategy is used to enhance adaptive control system.Compared with DSP control, the FPGA (Field Programmable Logic Array) control has High-speed computing, low power and highly integrated features. Taking the single shaft steering position servo system for engineering background, the dissertation researches on steering control system implemented by FPGA.Firstly, the paper analyzes the work principle of steering system, including BLDC(Brushless DC Motor), three-phase bridge driver menthod and position detection method. Then the mathematical model of the steering system is established. Based on the system model, three-loop control strategy with position loop, velocity loop and current loop is adopted. According to the different characteristics of each loop, the appropriate control algorithm is chosen.Secondly, for the steering system exist nonlinear factors, intelligent algorithms is introduced to traditional PID control. Fuzzy PID control strategy is applied to position loop regulators. As the steering gear system with time-variant, random noise and other factors, fixed rules of fuzzy control often seem inadequate. In order to compensate for this deficiency, adaptive methods are introduced to adjust fuzzy control rules in the process of self-adjustment. And build Matlab/Simulink simulation model to verify the performance of control algorithm.Thirdly, the servo system is devided into two parts: hardware and software. Hardware includes the power module, A/D conversion module and three-phase bridge driver module etc; designed soft modules includ the open-loop module,the current sampling module, PI algorith and fuzzy control module device ect. Simulate and verify the function of each module.Finally, from the aspect of system, FPGA design process is researched. And system test is finished on the FPGA platform, the results show that the system has good performances.