On-line adaptive control for minimizing slippage error while mobile platform and manipulator operate simultaneously for robotics mobile manipulation

Mecanum wheels can apply a flexible mobility to a mobile robot, in this paper, a mobile manipulation robot is designed with combination of a Mecanum wheeled mobile platform and a 7-degrees of freedom (DoF) robot manipulator. Due to the mechanism of Omni-directional mobility, the Mecanum wheeled robot suffers with slip errors on the free rollers, these errors may be reduced with additional sensors and appropriate feedback control. However, while the mobile platform and the manipulator operate simultaneously, the displacement of the center of gravity of the whole robot increases the complexity to the motion control. To solve this problem, we analyze and model the effect of inconsistency of slippage errors caused by the unbalance of normal force on the wheels, and propose an on-line adaption slippage model for the Mecanum vehicle to generate a better control system to reduce these errors. We proof the effectiveness by using our proposed adaption model and on-line compensation control with experiments.