Disturbance employment-based sliding mode control for 4-DOF tower crane systems

Abstract

To improve the transient control performance and to guarantee the satisfactory robustness simultaneously, in this paper, a disturbance employment-based sliding mode control (DESMC) method is designed for 4-DOF tower crane systems. To this aim, a nonlinear disturbance observer is first designed, based on which, the pros and cons of disturbance effects on the tower crane system are defined by a well-designed disturbance effect indicator (DEI). Then, the DESMC method is systematically proposed and discussed, based on the estimated disturbance and the introduced DEI. The stability and state convergence analysis are implemented by Lyapunov techniques without any linearization operation. It is shown that, except bad effects, system disturbance has potential good effects on transient control performance improvement, and hence, it is essential to introduce these beneficial effects into controller design. As far as we know, the designed DESMC method yields the first observation-based control without any linearization operation to the original 4-DOF tower crane dynamic model and achieves the first control method making full use of beneficial disturbance effects on crane systems. Several simulation results are presented to validate the effectiveness and robustness of the designed DESMC method.