Tracking Controller Using Normalized Quasi-velocities

In this paper a tracking controller expressed in terms of the normalized quasi-velocities (NQV) for rigid manipulators is proposed. These quasi-velocities introduced by Jain and Rodriguez, IEEE Trans. Robot. Autom., 11:571–584, 1995] are utilized here in order to reveal some useful features which are observable if we track a desired quasi-velocity trajectory. The presented controller in terms of NQV is exponentially convergent. Moreover, some geometrical interpretation of the normalized quasi-variables based on Riemannian geometry is given. It is shown that the controller can be helpful for evaluation and reduction of dynamical couplings existing in the system. As a result it is helpful at the design step of manipulators. The control strategy was tested in simulation on two 3 d.o.f. spatial manipulators.