Force/motion control of constrained manipulators without velocity measurements

In this paper the authors deal with the problem of force/tracking control of constrained manipulators without velocity measurements interacting with an infinitely stiff environment. They use a reduced-order model for which the coordinate space is restricted to a subset R where the Jacobian constraint is guaranteed to be nonsingular. In contrast to other similar approaches, the authors do not assume that the generalized trajectories belong to the subset /spl Omega/ all the time, thus our contribution is to prove that if the trajectories start within the subset /spl Omega/ they remain in it. Furthermore, we prove uniform asymptotic stability considering only position and force measurements.