Research On Synchronous Control Of Distributed Electro-hydraulic Servo System With Communication Delay

In large-scale projects,due to the large amount of work and the need for large driving force,it is an inevitable trend to drive large loads with electro-hydraulic servo system.In recent years,with the progress of technology and the improvement of engineering task requirements,the limitations of single electro-hydraulic servo actuator are gradually revealed,that is,it is unable to drive complex structure or high-quality machinery,while multiple electro-hydraulic servo actuators can get better results by cooperating and working together,so as to meet the industrial needs.In practical application scenarios,multiple electro-hydraulic servo actuators are often distributed driven,and in the distributed system,there is a certain time delay in the communication between each node.With the advent of industry 4.0 and intelligent manufacturing era,various fields have higher and higher requirements for the control accuracy and robustness of distributed electro-hydraulic servo system collaborative control.This thesis combines distributed electro-hydraulic servo system with multi-agent system theory,and uses nonlinear control methods such as feedback linearization and backstepping control to focus on the synchronous control of distributed electro-hydraulic servo system with communication delay,model load disturbance or parameter uncertainty.The research work of this thesis mainly includes the following aspects:1.Based on the analysis of the physical characteristics of electro-hydraulic servo system,the nonlinear mathematical model of electro-hydraulic servo system is established.For the nonlinear model,two schemes of linearization and backstepping control are adopted.2.For the linearization method,one scheme is to linearize the electro-hydraulic servo system model by using the feedback linearization method,design the state feedback through the Lie derivative,and construct homeomorphic mapping to complete the linearization of the model;Another scheme is to restrict the nonlinear term in the model to a linear term according to the Lipschitz condition.A disturbance observer is designed for load disturbance or parameter uncertainty,and based on the existence of communication delay,a control law is designed for all nodes in the distributed electro-hydraulic servo system to achieve consensus.The stability of the system is analyzed by Lyapunov stability theory,and the controller feedback matrix is obtained by solving linear matrix inequality.It is proved that the system is stable,and the error of three state variables of distributed electro-hydraulic servo system are uniformly bounded.Finally,the feasibility of the algorithm is verified by simulation.3.According to the backstepping control method,this thesis deliberate the consensus of distributed electro-hydraulic servo system.Aiming at the parameter uncertainty of the model itself,a terminal sliding mode disturbance observer is designed.Considering the existence of communication delay,by designing the virtual control quantity,finally iteratively design the backstepping control law to achieve consensus.By constructing the Lyapunov energy function and Lyapunov Krasovskii function for stability analysis,it is proved that the system is stable,and the error of three state variables of distributed electro-hydraulic servo system are uniformly bounded.Finally,the feasibility of the algorithm is verified by simulation.4.On the experimental platform of three node distributed electro-hydraulic servo actuator,the algorithm of feedback linearization and backstepping control designed in this thesis is experimentally verified.Experiments verify the rationality and effectiveness of the consistency control algorithm designed in this thesis.