Almost-global tracking of the unactuated joint in a pendubot
This work addresses the challenging problem of global tracking for underactuated systems, which is important for robotics and control theory, but the results are theoretical and not yet validated experimentally.
The paper presents a control law for almost-global asymptotic tracking of a smooth reference trajectory for the unactuated joint in a pendubot, and generalizes the scheme to n-link underactuated systems with at least as many actuators as unactuated degrees of freedom.
Tracking the unactuated configuration variable in an underactuated system, in a global sense, has not received much attention. Here we present a scheme to do so for a pendubot - a two link robot actuated only at the first link. We propose a control law for almost-global asymptotic tracking (AGAT) of a smooth reference trajectory for the unactuated second joint of the pendubot. The control law achieves almost-global tracking for any smooth reference trajectory specified for the unactuated joint. Further, we generalize the proposed scheme to an n-link system with as many (or more) degrees of actuation than unactuation, and show that the result holds.