This paper presents a novel fixed-time dynamic surface control (DSC) scheme for permanent magnet linear synchronous motors subject to external disturbances. Without employing the fractional power terms or complicated switching strategy to build the control law, a smooth fixed-time dynamic surface control scheme is proposed in this paper, which overcomes the potential singularity problem and explosion of the complexity issue often encountered in the fixed-time back-stepping design. To weaken the influence of external disturbances, a modified fixed-time convergence disturbance observer (FTDO) is explored to compensate the normal fixed-time DSC laws, thus largely improving the robustness of the proposed control scheme. The highlights of our design can be shown as threefold. First, it is free of the fractional powers items yet fixed-time convergence property. Second, it increases the robustness of the normal control design by constructing new FTDO. Third, it avoid the explosion of the complexity problem by virtue of modified fixed-time filters. The stability of the proposed control scheme is analyzed using the Lyapunov technique. Simulation results are given to illustrate the effectiveness of the proposed controller.

PMLSM，fixed-time dynamic surface control，disturbance observer