Output-feedback global tracking control of robot manipulators with flexible joints

Abstract

International audienceWe present a controller for flexible-joint robots without link velocity measurement. Our main result consists in a simple controller of the type proportional-derivative plus feedforward and a series of cascaded filters; the control design is reminiscent of classical backstepping control. To avoid the assumption that link velocities, accelerations and jerks are measured, we use approximate differentiation. The originality of our work lays in establishing uniform global asymptotic stability for the closed-loop system

A Separation Principle for Underactuated Lossless Lagrangian Systems

“…In this paper we extend the results of [18], [19] by assuming that the integrators' variables are not measured. We establish a separation principle for the same class of systems and we prove uniform global asymptotic stability of the origin.…”

“…The obvious disadvantage of the controller (10) is that it relies on the measurement of ξ i for all i ≤ m -see [19]. For instance, in the case of flexible-joint robots, this includes motor velocities.…”

“…Yet, it is assumed that each integrator variable is measured. In [19] we presented a controller for flexible-joint robots which ensures uniform global asymptotic stability for the closed-loop system under the assumption that joint, but not link velocities, are measured.…”

Robust adaptive output feedback tracking control for flexible-joint robot manipulators based on singularly perturbed decoupling

“…It is a typical method for almost all of the previous literatures 6,7,17 to focus on (15) to design the fast control law. Differently, in this paper, we will change the form of the fast system (15) by substituting (14) into it:…”

“…Output feedback control, as a technique to make the whole closed-loop system with only measurements of outputs, has aroused some interests in tracking control for flexible-joint robot manipulators. 14−18 Loría and Avila-Becerril developed an output feedback tracking (OFT) controller using back-stepping strategy, 14 in which approximate differentiation was applied to eliminate the link velocity, acceleration and jerk measurements. As presented, the position output feedback was only achieved for the links but not available for the joint motors.…”