Design Of Remote Monitoring System For Three-tank And Research On Decoupling Control Algorithms

Three-tank system is an experimental device which can be used to study the parameters control of liquid level,temperature and flow.It can be combined into many control loops and validate many control algorithms.Many control objects in industrial field can be abstracted into three-tank control model,which has important value in scientific research,teaching and industrial control fields.In order to give full play to the advantages of remote experiment and solve the coupling problem of multivariable system in industrial field,the research work is carried out from two aspects:the design of remote experiment control system for three-tank and the research of decoupling control algorithm.The main research contents are as follows:(1)According to the functional requirements of remote monitoring system for three-tank,the structure of data monitoring software and database are designed in detail.TCP/IP protocol is used to realize the communication between local terminal and data center server,XML format is used to transmit and receive data packets,and network programming technology is used to realize the real-time monitoring and experimental information display of the three-tank experimental platform.(2)Taking double-input-double-output three-tank as the research object,the process and method of establishing mathematical model are elaborated.The structural expression of mechanism model of three-tank is obtained by mechanism modeling method,and the controller model of three-tank is established by parameter identification method.(3)The structure and principle of multivariable control system are described,and the source of coupling of multivariable control system is analyzed.The principles of feedforward compensation decoupling,diagonal matrix decoupling and feedback compensation decoupling are compared and analyzed.According to the relative gain matrix of the model,the coupling of the three-tank control system is analyzed,and the feed-forward compensation decoupling controller model is established and simulated with the tool of MATLAB/Simulink.The feed-forward compensation decoupling control algorithm is applied to the three-tank test-bed and compared with the simple double-loop PID experiment.The results show that the feedforward compensation decoupling control algorithm can realize the decoupling function of the coupled system and improve the rapidity and stability of the system.(4)Analyzing the principle of the fuzzy control algorithm,using the advantage that the fuzzy control algorithm does not depend too much on the precise mathematical model,and combining the structural characteristics of the double-tank,the model of the fuzzy decoupling controller is established.The model of fuzzy decoupling liquid level controller is simulated,and then the fuzzy decoupling control algorithm is applied to the three-tank experimental platform,and the disturbance test is carried out.By comparing with the feedforward compensation decoupling control experiment,it is proved that the fuzzy decoupling control algorithm has stronger stability,response characteristics and robustness.The research of three-tank control algorithm shows that decoupling control algorithm has important practical value in multivariable control system.Compared with feed-forward compensation decoupling control algorithm,fuzzy decoupling control algorithm can further improve the performance of control system.