Robust noncollocated passive models of a flexible link with uncertain payload and joint inertia

In Proc. IEEE Conf. on Control Applications, Alaska, p. 971-975, Saad et al. used the passivity to control a noncollocated output consisting of the angle of rotation at the hub augmented with a weighted value of the angle of rotation of the link´s extremity. They proposed a technique for determining the closest output to the tip resulting in a passive transfer function. In this paper we extend their work to include robustness relative to the payload variation and joint inertia. We show in particular that for a particular choice of the proposed output, the transfer function is passive for all admissible values of the payload mass