Bounded Self-motion of Functional Redundant Robots

In this paper, we consider a problem how to exploit a task
space motion for lower-priority tasks when the end-effector motion allows
some deviation of the motion for the primary task. Using a common
redundancy resolution methods, the self-motion is only possible in the
null-space. Therefore, we propose a novel combination of controllers in
two spaces: in the task space and in the reduced task space, where DOFs
corresponding to spatial directions allowing the deviations are excluded.
The motion generated by the controller in the reduced task space is
mapped into the main task and by properly selecting the controller
parameters the resulting motion does not violate the constraints. To
demonstrate the effectiveness of the proposed control we show simulation
examples where motion in a constraint region is used to avoid joint
limits.