Method for performing position servo driving on electro-hydraulic proportional valve based on hybrid control

Abstract

The invention discloses a method for performing position servo driving on an electro-hydraulic proportional valve based on hybrid control in order to increase control accuracy and response speed of the electro-hydraulic proportional valve in position servo occasions. The method is characterized in that a hybrid control method based on PID and sliding mode variable structure algorithms is adopted according to position servo driving of the electro-hydraulic proportional valve, namely a PID controller is utilized to improve position instruction control accuracy of a proportional valve servo system when the system is in a steady state, a sliding mode variable structure nonlinear controller is utilized to improve instruction response and disturbance inhibiting ability of the system when an instruction of the system changes severely and disturbance is large, online identification is performed on the system through a recursive least square algorithm, system parameters are updated, and design of the PID and sliding mode variable structure controllers is performed in real time. The method has the advantages of being high in response speed and steady accuracy, strong in robustness and capable of effectively compensating nonlinear links in the proportional valve, and can be used for improving driving accuracy of the proportional valve.

Description

technical field [0001] The invention relates to a position servo driving method of an electro-hydraulic proportional valve. Background technique [0002] The electro-hydraulic proportional valve position servo drive system is an electro-hydraulic proportional position servo control system using electro-hydraulic proportional valves as actuators. Compared with ordinary electro-hydraulic servo control systems, it has the advantages of low price, energy saving, strong oil pollution resistance, Reliable work, convenient maintenance, high power density and other characteristics, it is very suitable for the industrial field, and has been widely used in automatic hydraulic equipment. However, the electro-hydraulic proportional valve position servo drive system uses a proportional valve as the actuator. Compared with the servo valve, the proportional valve has a lower bandwidth and has a nonlinear link of a neutral dead zone. A certain drift will occur due to other reasons, these f...

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Problems solved by technology

However, for the nonlinear link of the neutral dead zone of the proportional valve, the PID controller can only perform simple compensation, and the control accuracy cannot be guaranteed. For the drift of the system parameters due to factors such as temperature and pressure, the traditional PID controller The parameters are fixed, and parameter compensation cannot be performed, and the control accuracy and stability margin of the system cannot be guaranteed

Therefore, compared with the electro-hydraulic servo position drive system, the traditional electro-hydraulic proportional valve position servo system using PID controller has poor control accuracy and low system bandwidth.

This is mainly due to two reasons: one is that the proportional valve has a neutral dead zone, which is essentially a nonlinear system, while the PID controller is a linear controller, and it is difficult to achieve high control accuracy for a nonlinear system; the other is that the control system During the running process, the system model parameters will drift to a certain extent due to reasons such as temperature and pressure. There are no effective measures in the PID algorithm to correct and compensate for such parameter drift. If the parameter drift is too large, the controller does not perform corresponding adjustments. Parameter adjustment will lead to lower system control accuracy and even instability.

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