Sliding Mode Backstepping And Model-free Adaptive Coordinated Control Of A Dual-tank Liquid Level Syste

In the field of industrial process control,the two-tank liquid level system has the characteristics of strong nonlinearity and model uncertainty,and there are the effects of external disturbance and parameter perturbation.Therefore,in order to realize the rapid,stable and accurate control of the two-tank liquid level system in industrial process,completely different controllers are designed from the perspective of system model and data drive respectively,and the collaborative optimization control between the two kinds of controllers is realized through coordinated control strategy.The research contents of this paper are as follows1.An adaptive sliding mode control method based on disturbance observer is designed.For the two-tank liquid level system with external disturbance,an adaptive sliding mode approach law is adopted to improve the dynamic performance and control precision of the system,and reduce chattering,the disturbance of the system is estimated by nonlinear disturbance observer.The experimental results show that the proposed control method has higher control accuracy and stronger anti-interference ability than other traditional control methods.2.A coordinated control strategy based on PID and model-free adaptive was designed for the two-tank liquid level system with strong nonlinearity and difficulty in establishing accurate mathematical model in practical industrial process.PID controller plays an important role in the initial dynamic stage of the system,and ensures the response speed while obtaining the system I/O data.MIMO model-free adaptive terminal sliding mode controller plays an important role,which improves the control accuracy of the system.The design of the controller only depends on the I/O data and compact format dynamic linearization technology of the system.The coordination control between PID controller and model-free adaptive terminal sliding mode controller is realized by this strategy,which is independent of the system mathematical model and the initial value of pseudo partial derivative in model-free control method is not needed.Simulation results verify the effectiveness of the proposed control strategy.3.A coordinated control scheme for two-tank liquid level system based on backstepping and data-driven is designed,and the generalized disturbance is considered.Firstly,the integral backstepping controller is derived according to the system mathematical model.Secondly,after designing the data-driven discrete sliding mode controller,the discrete extended state observer is introduced to estimate the generalized disturbance of the system.The data-driven control has nothing to do with the mathematical model of the liquid level system,but only depends on the system I/O measurement data.A coordinated control scheme based on error Gaussian function is adopted.In the initial dynamic stage of the system,backstepping control ensures that the liquid level system can immediately start normal operation and obtain a large amount of I/O measurement data,and there is no need to study and select the initial value of pseudo partial derivative.The simulation results show that when the coordinated control scheme based on backstepping and data-driven is adopted,the system has good steady-state and dynamic performance and strong robustness.To sum up,on the basis of studying the control method based on the system mathematical model and the model-free adaptive control method based on the system I/O data,the coordinated control scheme of two-tank liquid level system based on model-based control method and model-free adaptive control method is designed.Not only the precise control and disturbance suppression of the liquid level system are realized,but also the better dynamic and steady performance is obtained.In addition,the I/O measurement data are fully utilized,and the control method based on system model simplifies the process of giving accurate initial value in model-free adaptive control.