NONHOLONOMIC BEHAVIOR IN REDUNDANT ROBOTS UNDER KINEMATIC CONTROL

We analyze the behavior of redundant robots when the joint motion is g enerated by inverting task velocity commands through a kinematic contr ol scheme. Depending on the chosen inversion scheme, the robot motion is subject to differential constraints that may or may not be integrab le. Accordingly, we give a classification in terms of holonomic, parti ally nonholonomic, and completely nonholonomic behavior, pointing out also the relationship with the so-called cyclicity property, This gene ral classification is illustrated by means of several examples. When t he kinematic control scheme is nonholonomic, the whole configuration s pace of the robot is accessible by a proper choice of the task input c ommands. Under this assumption, we address the joint reconfiguration p roblem, namely the design of end-effector velocity commands that drive the robot to a desired joint configuration. To solve this problem, it is possible to borrow existing methods for motion planning of nonholo nomic mechanical systems, such as the sinusoidal steering technique fo r chained-form systems.