Experimental Application of Time-Varying Sliding Modes for Hoisting Crane Position Control with Constraints

In this paper we propose the robust sliding mode control strategy for the position control of a hoisting crane. The strategy employs the time-varying switching lines. Two alternative solutions are presented - for the line shifted with a constant velocity and for the line moving with a constant deceleration. Line parameters are optimally synthesized using the ITAE criterion, taking simultaneously into account additional constraints imposed on the velocity and acceleration of the payload motion dynamics. By appropriate design of the switching lines the proposed control law gives non-oscillatory convergence of the regulation error in a closed-loop system with guarantee of constraints preservation during the whole regulation process. Theoretical considerations are verified by the experimental tests conducted on the laboratory scale hoisting crane system.