Research On Sliding Mode Predictive Control For Discrete Time-delay Systems

The phenomenon of time-delay generally exists in practical applications such as electric power and machinery.Therefore,the discussion and analysis of the time-delay system has received continuous attention from relevant scholars.The traditional sliding mode control method has a good effect on solving the problem of time delay.However,there are many related research results in the continuous system,while the comprehensive analysis results for the discrete controlled object are relatively few.Because of the complexity of discrete-time system analysis and the time-delay phenomenon in the actual system,it not only makes the design of sliding mode control algorithm more difficult,but also makes the closed-loop system difficult to have the desired dynamic performance.In this paper,sliding mode control algorithm and predictive control algorithm are combined to further improve the performance of discrete-time systems with time-delay.The specific research contents are as follows:1)In order to improve the robust performance of the SISO constant-time discrete system under colored noise interference and ensure the stability of the closed-loop system,the implicit generalized predictive self-tuning control algorithm is introduced into the sliding mode control by designing the sliding mode prediction algorithm.Unbiased estimation is performed to ensure the stability and strong robustness of the system,which further reduces the convergence time of the system output and suppresses chattering.2)In order to improve the performance of discrete-time systems with time-varying state delays,parameter perturbations and linear disturbances,and reduce the conservatism of state delays,the double power function is introduced into the reference trajectory.The sliding mode predictive control algorithm is designed by using the global sliding mode surface.Based on multi-step feedback correction and rolling optimization technology,the optimal control law of the system without constraints is obtained,Thus,the stability of the closed-loop system is guaranteed and the upper bound of the state delay is improved,thechattering problem of the sliding mode is alleviated,and the convergence speed of the system is accelerated.Simulation results show the feasibility and superiority of the proposed algorithm.3)For discrete time-delay systems with nonlinear disturbances and parameter perturbations,a sliding mode prediction algorithm is designed to study the tracking control of the system output.First,the tracking error and state delay are used to design the sliding mode prediction model.The Lyapunov function is used to prove the stability of the ideal sliding mode,and the reference trajectory is designed to ensure that the sliding motion moves in the quasi-sliding mode.Finally,the particle swarm optimization algorithm is used to optimize the rolling mode.Process improvement.The effectiveness and superiority of this algorithm are verified by simulation.