Recovering model consistence for force and velocity measures in robot hybrid control

Hybrid Control for robots in contact with the environment is intended to separately impose end-effector motion and contact force along different directions, determined on the base of an available environment model. Since measured forces and velocities in practice do not agree exactly with the model, some filtering procedure is required for recovering consistence, before the control phase. In this paper some issues are discussed on the filtering process, addressed as the resolution of an algebraic overdetermined linear system, solvable approximately by means of weighted pseudoinversion. A basic issue is shown to be the choice of the weight matrix that, if properly defined, allows to overcome the theoretical difficulties recently pointed out by some authors. Examples clarify the developed theory.