Variable Load Electro-Hydraulic Servo Control Technology Research

L Low-speed big torque control system plays an important part in modern life, and it is widely used in engineering machinery, mining machinery, and civil-military important construction equipment as well as among high-loaded hydraulic lathe. In these systems, the simple low-speed big torque hydraulic pressure motor could meet the need of design and use well. But with the development of modern society, a variety of new design requirements come into being with respect to different extreme working conditions——more secure, more convenient, more environmental etc. As to low-speed big torque control, it should not only reach higher speed modulating and bigger torque revolving requirements, but it is also required that the equipment can achieve certain long-range control and higher control accuracy.A design analysis of the variable load electro-hydraulic servo control technology research plan of certain company is given in this thesis. The drive shaft's movement characteristics and control law is researched, if given the motion track, displacement curve, load curve, the rotation inertia curve etc. boundary conditions; the digital control scheme used to establish electro-hydraulic servo drive and positioning is studied; the mathematical model and system simulation is conducted; According to the analysis results, electro-hydraulic servo system design scheme is optimized, and the key components technical parameters is determined based on Rexroth's hydraulic manual, digital control algorithm is formulated, the driver, the positioning control, system digital and other technologies are resolved and verified.The design methods of this thesis are:hydraulic system schematic diagram is designed; Based on the analysis of technical data provided by the company, the maximum torque in the system design is determined, and then the required hydraulic motor displacement, speed reducer, and type of hydraulic pump are worked out., then the matched dynamo, oil and hydraulic servo valve type are chosen; displacement transducer and is picked out according to the angular speed of the system; demodulator which modulates alternating current into direct current is selected.According to the selected device type, the feedback performance of hydraulic servo system is analyzed, and the dynamic feedback equation and system steady-state model of hydraulic servo system is obtained.Based on system's steady-state model, the PLC control system is drawn up, PLC control system is analyzed, and PID correction design is given based on analysis of the design parameters of the PLC.According to above concluded servo system model, the MATLAB/simulink simulation is carried out; the open-loop transfer function and the steady-state error of the designed system are worked out. Based on control system, PID correction design is conducted, and then the conclusion is reached.