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Mathematical Problems in Engineering
Volume 2015, Article ID 574874, 11 pages
http://dx.doi.org/10.1155/2015/574874
Research Article

Four-Channel Teleoperation with Time-Varying Delays and Disturbance Observers

1Higher Technical School of Industrial Engineering, University of Vigo, 36310 Vigo, Spain
2Higher Technical School of Computer Engineering, University of Vigo, 32004 Orense, Spain

Received 3 June 2015; Revised 17 July 2015; Accepted 26 July 2015

Academic Editor: Yuqiang Wu

Copyright © 2015 Emma Delgado et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper addresses the robust stability of teleoperated systems under the four-channel architecture, affected by time-varying communication delays and using disturbance observers. It is based on our previous work which provides a framework for robust stability against delays with bounded variation and a bounded time-derivative, using structured singular values (SSV). The main new feature here is the inclusion of disturbance observers (DOBs). The DOB concept is well-documented and relevant to many applications, since only position (but not force) measurements are usually available. In this paper, we adapt two DOBs (master and slave) to our generic framework, by representing them as stable, fast filters affected by the uncertainty in the plant modelling. Our main result is an SSV test to verify robust stability. The simulation results confirm the usefulness of this approach.