Study On Unconventional Synchronous Control Of Electro-hydraulic Servo System Under Bidirectional Loading

Hydraulic synchronous control is a very important technology in the industrial field. But because of the effects of the coupling between multi-cylinder systems and the variety of the load, make it more difficult to research the high precision synchronizing control technology. In the paper, the author have make a deep analysis, simulation and experimental research of unconventional synchronization control of an electro-hydraulic servo system. It is carried out on the bidirectional dynamic triaxial apparatus synchronous control system platform which is under the support of the Natural Science Foundation of China. The specific researches as follows:The mathematical model of the unconventional synchronization control of the dynamic triaxial apparatus under bidirectional loading is developed, and the research of the dynamic and static characteristics of the system is carried out to analyse the stability behavior and the dynamic performance. According to the analysis result, the author put forward the improvement and a revision of the scheme in order to make the system have a good dynamic performance.The theoretical research on the nonlinear friction of the unconventional synchronization system with single cylinder is done. The author mainly researches a control strategy of frictional compensation based on LuGre friction model, propose a kind of parameter identification method and design the state observer based on the LuGre model. Finally an experiment and simulink simulation is carried out, and the results shows that:the tracking error of the system with friction compensation is reduced by about50%than the system without friction compensation and have a good compensation effect. The results also verify that the friction compensation based on the LuGre model can reduce the effect of the friction of hydraulic system effectively.In consideration of the tracking accuracy and synchronous accuracy of the bidirectional excitation dynamic triaxial apparatus system, several control strategy is discussed:the phase error compensation strategy based on the iterative control theory; prevent integral saturated PID control method; non-linear varible gain PID control technology and cross-coupling control strategy. The control strategies are analysed particularly and several experiments are done. The results shows that:firstly, the design of the phase compensator based on iterative learning control algorithm can compensate the error effectively, the control method can be a reference of phase compensation and has practical engineering value; secondly, the tracking error of the system with non-linear varible gain PID controller is reduced by about50%than the system with conventional PID controller, and can improve the tracking accuracy and robustness of the system effectively; thirdly, by compared experiments, it shows that the synchronous error of the syestem with the compensation based on cross-coupling control strategy is reduced by about40%than the system with the compensation based on synchronized Master Command Approach control strategy, and can improve the synchronizaion performance of the double cylinder system effectively.