Compensation of discrete contact state errors in multi-fingered manipulation

This article embeds the control problem of multi-fingered robotic manipulation in the framework of hybrid discrete-continuous dynamical systems. A hybrid discrete-continuous control architecture enables a hand to robustly manipulate objects. The paper focuses on the ability of the hybrid controller to compensate for errors in the discrete contact state of the manipulation system. Such deviations of the actual contact situation of fingers in the systems from the desired one may degrade the performance of task execution or even cause instability of the grasp. An active contact search and a following grasp stabilization sequence corrects the contact state and allows for further regrasping tasks. Results of dynamic simulations with a four-fingered hand manipulating a sample object demonstrate the robustness improvement in grasping control as achieved by the proposed approach for discrete error compensation.