Electro-hydraulic Position Servo System Of Multi-cylinder Synchronous Control Method Study

Since strong coupling phenomenon among multi-channel hydraulic servo cylinder subsystems and the role of disturbance, as well as the complex of working conditions and load in multi-degree of freedom electro-hydraulic position servo system, high precision of multi-cylinder synchronous control has been a problem in hydraulic engineering. In this paper, according to the characteristics of nonlinear, time-varying, non-linear mathematical model of multi-cylinder synchronous system is established based on a large number of references at home and abroad, then three kinds of control strategies——PID, model reference fuzzy adaptive control and internal model control are applied to the four-cylinder synchronous control system, and a simulation study is carried out.PID controller is designed through the combination of "master-slave mode" and "equal mode". The largest running position cylinder serves as reference cylinder, Then, the position of the other three cylinders were compared with reference cylinder, the errors are used as the input of PID controller, thereby the speed of hydraulic cylinders are regulated with PID control algorithm. PID control simulation results show that a good balance State is maintained in less precision or small interference occasions. But for high-precision or strong interference occasions, PID control can not satisfy the control requirements.Aiming at the poor anti-interference problem of PID control four-cylinder synchronous system, model reference fuzzy adaptive control is proposed to four-cylinder synchronous system. The output of reference model is used as the desired output response, the error, which is the difference between expected output and the actual output, and its derivative serve as the inputs of fuzzy adaptive institution, the parameters of the PI controller are adjusted on-line according to fuzzy reasoning, so that the output of the controlled system tends to the reference model output. The simulation results show that the uncertainties of the system are overcome effectively, and dynamic performance and anti-interference ability of system are improved, so it achieves satisfactory control results.Pole-zero cancellation method is used for the design of internal model controller, the feedback controller is obtained according to the equivalent relationship between internal model control structure and the feedback control structure. Then the systems with interference, without interference, and with parameters changes are simulated respectively. The results show that the internal model control four-cylinder synchronization system is of good response speed and robustness, and only one parameter is adjusted, the relationship between parameter adjustment and dynamic quality or robustness is clearer.