Stability compensation of a mobile manipulator by manipulator motion: Feasibility and planning

In order for a mobile manipulator to move stably (not overturn) and execute the given motions of the end-effector and the vehicle simultaneously, a manipulator must have redundancy. By using this redundancy, it is possible to perform tasks at an optimal manipulation configuration when the robot is stable, and recovering the systems's stability when the robot is unstable. The ability to recover stability by this manipulator compensation motion is limited. Thus in order to ensure the feasibility of stability compensation, the task plan or vehicle motion must be within this ability. In this paper, first the concept of stability compensation range by static posture change is proposed. Then, within the stability compensation range, the compensation motion of a redundant manipulator considering the manipulation configuration and the system stability is derived, given the motions of the end-effector and the vehicle. Finally, the effectiveness of this method is illustrated by simulation experiments.