Search

A dual fixed‐time terminal sliding mode control strategy is proposed to address the problems of magnetic coupling, end effects and unknown disturbances in linear synchronous motor maglev systems, which ensures that the system tracking trajectory achieves fixed‐time convergence and high accuracy. First, a fixed‐time integral terminal sliding mode surface is designed to obtain the desired dynamic properties and avoid the singularity problem. Second, based on the dynamic sliding mode theory, a second fixed‐time terminal sliding mode surface is designed to weaken the chattering problem in the controller by replacing the discontinuous switching signal with a continuous switching rule. The proposed controller is theoretically proved to be fixed‐time convergent and the convergence time is independent of the initial conditions by means of the Lyapunov function and the fixed‐time convergence theorem. Finally, simulations and experiments are carried out on a linear maglev experimental platform. Compared with the fixed‐time sliding mode control, the simulation and experimental results show that the proposed strategy improves the tracking accuracy by 37.5%, the convergence speed by 33.3%, and the robustness by 42.1%, which has the advantages of fast convergence speed, strong robustness, and weak chattering. [ABSTRACT FROM AUTHOR]

This study aims to build a novel tracking control algorithm using a finite-time disturbance observer which obtains fast convergence within a predetermined amount of time and strong stability for a class of second-order nonlinear systems. Firstly, a nonlinear sliding mode manifold with fast finite-time convergence is introduced. Then, according to the designed manifold for the guarantee of finite-time convergence and robustness stabilization, a nonlinear control algorithm based on theory of finite-time control is developed. Specifically, the information of the lumped uncertainty was achieved by a new finite-time Disturbance Observer (DO). Thanks to the synthetic advantages of the above techniques, the designed controller marked with powerful features including a practical design, fast convergence rate, high precision, a convergence of the control errors in finite-time, along with impressive small chattering in the control actions. Furthermore, the control proposal also eliminates the necessity of the upper boundary of the uncertainties affecting the system and its finite settling time can be estimated in advance by designating the appropriate design parameters. The finite-time stability of the proposed DO, sliding surface, and control algorithm has been fully confirmed by Lyapunov principle. Trajectory tracking simulation for a 3-DOF manipulator and trajectory tracking experiment for a Maglev System (MLS) has been performed under different operating conditions using MATLAB/SIMULINK to testify the effectiveness and feasibility of the suggested strategy.

For practical maglev systems, the mutual effects among the bulk superconductor and the permanent magnet are primarily investigated to provide useful implications for the design. This paper proposed a general simulation method to demonstrate the electromagnetic behaviors of a levitation system. The basics properties including the distributions of the induced current and the levitation/guidance force of a bulk superconductor have been calculated while moving in the nonuniform magnetic field generated by a permanent magnet guideway. This numerical method is based on solving the partial differential equations time dependently and adapted to the commercial finite element software COMSOL Multiphysics 5.3. It is worth mentioning that relative movements are solved to simulate more real test scenarios with the moving mesh and automatic remeshing in COMSOL. Simulation results are intuitive for the generation of electromagnetic behaviors and show a good consistency with previous experimental data. We conclude that this simulation method can be a powerful tool for researchers and engineers to investigate analogous problems with a greater level of flexibility and expandability. [ABSTRACT FROM AUTHOR]

This paper deals with the design, construction, and especially the testing of a new magnetic levitation (maglev) train driven by an air-cored tubular linear induction motor. The proposed new design topology uses only one force-generating system (motor) to produce the three forces required in a maglev system: propulsion, levitation, and guidance, whereas classical maglev trains use separate motors or permanent magnets to produce each of these forces. Moreover, the system eliminates the need for control of the levitation and guidance forces. This paper presents a condensed design guideline, simply explains the implementation process of a laboratory-scale prototype, shows in detail the experimental test results—including the low-damping problem—and then addresses the advantages of the proposed system over existing maglev systems. [ABSTRACT FROM PUBLISHER]