Trajectory tracking of car-like mobile robots using mixed H2/H∞ decentralized variable structure control

In this paper, a mixed H₂/H_∞ decentralized variable structure control for car-like mobile robot (CLMR) was developed. Under no uncertain condition, a linear discrete-time dynamic model for steering and translation subsystem was individually achieved by the recursive least-squares parameter estimation. Then the H₂-norm of output error and weighted control input was minimized to obtain a control such that smaller energy consumption with bounded tracking error was assured. In addition, the H_∞-norm of weighted sensitivity between output disturbance (caused by the interactions among subsystems, modeling error, and external load) and output error was minimized to attenuate the effect of output disturbance. For further improving system performance, a switching control for every subsystem was designed. The experiment of CLMR for tracking an "S" trajectory was carried out to evaluate the usefulness of the proposed control system.