A study of the tracking control of an transfer crane using nonholonomic constraint

The automation of container cranes is one of the significant factors of global competitiveness, by improving the celerity of distribution processing in container terminals. Most container terminals operate with Rubber-Tired Gantry Crane (RTGC) type container cranes. However, the RTGC displays various uncertainties, including slips and scarcities of air pressure of tires during tracking mode, and position error during suspension, and therefore it is difficult to secure reliability for the automation level, and systematic research developments remain in inadequate status. First, the problem of tracking control that tracks the route determined at the yard with high speed and accuracy must be solved, to achieve automation of the RTGC. Since it is virtually impossible to use the steering unit of the RTGC, there exist constraints of having to perform tracking control through the speed control of both drive units. Thus, the RTGC is a system with nonholonomic constraint, as the typical nonlinear system driven by tires. In this study, the nonholonomic system is applied to conduct the overall system modeling, through kinematic modeling and dynamic modeling of the RTGC. Furthermore, the sliding mode control technique is applied as one of the discontinuous time invariant control techniques, for the purpose of simultaneously accomplishing system stabilization, and overcoming model uncertainties. The gains of sliding planes will be analytically found by using the LMI technique, and performance of the proposed control unit will be confirmed through the experiment.