KINEMATIC INSTABILITY OF KINEMATICALLY CONSTRAINED MANIPULATORS UNDER PURE FORCE CONTROL

In this paper, we consider the problem of force control for kinematically constrained manipulators (KCMs). In particular, we show that the force component selection is not appropriate in general to solve the force control problem for KCMs. Moreover, by formulating the problem in the joint space, we show how to properly design a stable force controller for KCMs subject to arbitrary external forces applied to their end-effector. Experimental results with a kinematically constrained laparoscopic comanipulator illustrate these propositions.