| Under the same conditions,the electro-hydraulic servo control system has advantages such as large output force/torque,fast dynamic response,precise control precision and more compact structure compared with electric or pneumatic control systems.This makes electrohydraulic servo control systems widely used in the industry.With the continuous research and use of electro-hydraulic servo technology in engineering,the industry has put forward more stringent requirements on its performance indicators and costs such as instantaneous flow,positioning accuracy and dynamic response.Under the premise that the research progress of large-flow servo valve is not ideal and the price is expensive,this paper proposes a method of parallel control of large flow with dead zone proportional valve and the servo valve with low flow high frequency response.The method solves the problem that the system cannot balance high-precision positioning control,high dynamic following response and large instantaneous flow fast moving at low cost,and an adaptive robust control(ARC)algorithm based on dynamic allocation of traffic is designed for the system.The main research contents are as follows:(1)Perform mathematical modeling and model analysis of the dual valve control cylinder system according to the theory of single valve control cylinder.At the same time,the flow balance equation of the double valve control cylinder is derived.And the actual parameters of the components in the system and the theoretical parameters in the equation are calculated.(2)In order to solve the problem of redundant flow in parallel systems,a dynamic traffic allocation strategy is proposed according to different operating conditions of the system.And through the flow-signal relationship of the offline identification valve,the flow distribution strategy is converted into a control signal distribution strategy.On the basis of considering the dynamic distribution of flow,in order to solve the nonlinear,unknown parameters and unknown modeling of the control system,based on the flow balance equation of the dual valve control system,the ARC algorithm of the control system is designed and derived.(3)In order to more effectively reflect the proportional valve dead zone and low frequency response characteristics,and the influence of the nonlinearity of the hydraulic system on the control performance of the system.The AMESim software and Simulink software were used to jointly simulate the dual valve parallel system and the two types of single proportional valve PID control systems.It can be seen that the double valve parallel control system compares the tracking accuracy of the single proportional valve PID control system.In the step signal,the maximum deviation of the steady state is reduced by 93.7%,and the response time is reduced by 13.3%;in the ramp signal,the maximum steady-state deviation is reduced by 99.79%;in the sinusoidal signal,the phase difference is reduced by 95% and the amplitude deviation is reduced by 91.4%.(4)The overall structure and control system of the testing machine were built,and the control program and operation interface were written by VS software.Under the sinusoidal tracking curve,it is verified that the tracking accuracy of the dual valve control is improved compared with the single proportional valve PID control system,the phase difference is reduced by 80%,the amplitude deviation is reduced by 78.96%,which verifies the effectiveness of the control algorithm designed in this paper. |
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