Abstract
An Adaptive switching control scheme is proposed for a planar gantry crane. The length of the crane cable is subject to change in different operating conditions. Based on this control scheme, the control to the planar gantry crane can be switched among several controllers, each designed for a different fixed-length nominal model. Each “fixed-length controller” consists of double loops, one of which is a state feedback controller, and another one is a nonlinear controller aimed to compensate the unknown friction. An “unknown-input observer” is designed to estimate the state variables in order to avoid the influence of the unknown friction. The stability of each “fixed-length controller” is guaranteed by Lyapunov's direct method. Experimental results are presented to demonstrate the effectiveness of the proposed control scheme.
