| With the increasing complexity of the research objects in actual projects,nonlinear problems inevitably exist in the controlled objects,which makes the study of nonlinear systems receive extensive attention.By virtue of its strong robustness,insensitive to external disturbances,high response,simple design and physical application,the sliding mode control has been extensively applied in the control of nonlinear systems and exhibits excellent control effects.Therefore,this paper mainly focuses on the sliding mode control problem of nonlinear systems with the characteristics of nonlinear actuator failures,multi-time-scale phenomena,random jumps.The main research content is shown below:1.For a class of nonlinear semi-Markov jump systems,the problem of the finite-time asynchronous sliding mode control is studied.The main purpose is to design an asynchronous sliding mode controller to ensure that the closed-loop system is mean-square finite-time bounded via the event-triggered mechanism.Considering that the system modal information cannot be fully measured by the controller in real-time,the asynchronous control method is applied to the design of the controller immediately.In addition,an event-triggered mechanism is introduced,which determines whether data transmission should be performed according to a threshold condition to reduce the burden of communication transmission.Then,with the help of the mode-dependent Lyapunov function and the finite time theory,sufficient conditions are obtained to ensure the closed-loop system is mean-square finite-time bounded in the whole finite-time interval.Finally,a tunnel diode circuit model is utilized to illustrate the feasibility of the designed controller.2.Aiming at a class of nonlinear Tagaki-Sugeno fuzzy systems under the permanent magnet synchronous motor model,the problem of the memory-based fault-tolerant sliding mode control is investigated.The main purpose is to design a memory-based sliding mode controller under a fault-tolerant strategy to ensure that the closed-loop system is asymptotically stable while meeting an H_∞performance.Taking into account the possible actuator fault caused by environmental factors,a fault-tolerant control strategy is introduced to ensure the system performance when designing the controller.In addition,the memory parameters are introduced in the design of the sliding surface.Then,by means of the memory parameter-dependent Lyapunov functional and sliding mode control theory,sufficient conditions are obtained to ensure the existence of the aforementioned requirements and the feasible solution.Finally,the developed control strategy is applied to the permanent magnet synchronous motor model to verify its effectiveness.3.For a multi-time scale permanent magnet wind power model-based nonlinear systems,the sliding mode control problem is investigated via the disturbance observer.The main purpose is to design a disturbance observer-based sliding mode controller to guarantee the closed-loop system is asymptotically stable and satisfies a certain H_∞performance.In consideration of permanent magnet wind power systems with the multi-time scale phenomenon,adopting a singular perturbation method to model and analyze the target system,the improved perturbation parameter-dependent sliding mode surface is constructed.Then,through the perturbation parameter-dependent Lyapunov function and singularly perturbed method,sufficient conditions are obtained to ensure that the afore-mentioned requirements are satisfied.By solving the convex optimization problem,feasible solutions of the objective sliding mode controller are obtained.Finally,the effectiveness of the proposed method is verified by investigating a permanent magnet wind power system model with specific parameters. |
