Research On Hydraulic Control System Of Turning Device Of Turner

With the development of agricultural machinery towards automation and intellectualization,turner,as the core equipment of dynamic composting,has higher and higher quality requirements on the hydraulic system of turner in the market.The hydraulic system of the traditional turning device adopts the "constant displacement pump-constant displacement motor" loop,but there are some shortcomings,such as unable to adapt to bad working conditions,poor system adjustment ability,low efficiency,etc.Under this background,starting from the design of the hydraulic control system of the turning device,the closed loop of the pump motor is applied to the hydraulic system of the turning device,and the accumulator is added to the system to improve the pressure impact of the system.The simulation and test results show that the dynamic characteristics and robustness of the system are enhanced by introducing the motor speed correction controller into the system,and the control effect of the fuzzy self-tuning PID control is better than that of the PID control.This work has important academic value to improve the performance of the turning device,and has important engineering significance to promote the application of the pump motor closed loop.The detailed work and main conclusions of the paper are as follows:(1)Clarify the design requirements of the hydraulic system of the turning device,analyze the hydraulic system loop and speed control scheme,and determine that the system uses the "variable displacement pump-constant displacement motor" closed loop;Conduct detailed design and model selection for the system,and add cooler for the system through heating and heat dissipation calculation of the system to ensure the heat dissipation capacity of the system;The system is divided into several classic links,and the transfer functions of each link are established and integrated by force balance equation and flow continuity equation,so as to obtain the overall mathematical model of the system;Through the open loop Bode diagram of the system,the stability and controllability of the system are proved.(2)Through analyzing the dynamic characteristics of the system,it proves the necessity of introducing the motor speed correction controller into the system.Then,the deficiency of PID control is analyzed and studied,and the fuzzy self-tuning PID control is proposed for the system;The PID parameters are adjusted by Ziegler-Nichles method,and the fuzzy rules are studied to obtain the fuzzy rules table.The fuzzy control is realized by the Fuzzy Logic Designer module in MATLAB.(3)The physical model and control model of the system are established by using Hy Pneu-Simulink co-simulation platform.The main parameters of pump and motor are compared and studied by using two kinds of controllers.The simulation results show that the control effect of fuzzy self-tuning PID is better than that of PID control;To solve the pressure impact problem of the system,an accumulator is added to the system for improvement.Through orthogonal test and range analysis,the influence of the three main parameters of the accumulator on the pressure overshoot and adjustment time of the system is obtained: the inner diameter of the connecting pipeline>the pre-charge pressure>the accumulator volume,and the pressure overshoot of the optimized index parameters is reduced by 4.93%.(4)Based on the original test stand,the pump motor circuit test stand is designed,and the measurement and control system of the test stand is designed,so that the PID control and fuzzy self-tuning PID control can be realized in Lab VIEW;The dynamic response and robustness tests are conducted on the rotating speed of the motor.The test results are consistent with the simulation results,and the reliability of the simulation results is verified.