A new trajectory control of a flexible-link robot based on a distributed-parameter dynamic model

Abstract

The objective of this study is to develop a new trajectory-tracking control method, free from the so-called spillover instability, for a flexible-link robot. Based on a distributed-parameter dynamic model (a partial differential equation), a new moment-feedback trajectory-tracking control scheme is designed for a one-link flexible robot having a payload at the free end, in which zero geometric boundary conditions at the hub end and non-zero dynamic boundary conditions at the free end are taken into account. The proposed control is then extended to an adaptive scheme to cope with parametric uncertainties. The proposed control is stable for trajectory-tracking control and asymptotically stable at desired goal positions, which is proven by using the Lyapunov stability theorem. In addition, the proposed trajectory-tracking control, based on a distributed-parameter dynamic model, does not have the spillover problem. Furthermore, the control performance is guaranteed regardless of the magnitude of desired angle of rotation, which does not require any additional actuators such as piezoelectric actuators on the link and boundary force or moment actuators at the free end. The effectiveness of the proposed control has been shown by experiments.

Acknowledgements

The flexible-link robot was designed and built by Seniors Roxsana Mehrabadi, Julien Prevost and Katherine Mills under the supervision of the author and Mr Del Segura as a senior project of the Department of Mechanical Engineering in the Spring semester, 2002. The real-time programming and experiments were performed by Mr Yi Liang and Mr Julien Prevost under the supervision of the author. The author greatly acknowledges their efforts and contributions for this study.