Teleoperation in the presence of varying time delays and sandwich linearity in actuators

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Hashemzadeh F., Hassanzadeh I., Tavakoli M.

Automatica, vol.49, no.9, pp.2813-2821, 2013 (SCI-Expanded) identifier

  • Publication Type: Article / Abstract
  • Volume: 49 Issue: 9
  • Publication Date: 2013
  • Doi Number: 10.1016/j.automatica.2013.05.012
  • Journal Name: Automatica
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.2813-2821
  • Keywords: Actuator saturation, Asymptotic stability, Nonlinear teleoperation, Sandwich linearity, Varying time delay
  • Istanbul Technical University Affiliated: No


In this paper, a novel control scheme is proposed to guarantee global asymptotic stability of bilateral teleoperation systems that are subjected to time-varying time delays in their communication channel and sandwich linearity in their actuators. This extends prior art concerning control of nonlinear bilateral teleoperation systems under time-varying time delays to the case where the local and the remote robots' control signals pass through saturation or similar nonlinearities that belong to a class of systems we name sandwich linear systems. Our proposed controller is similar to the proportional plus damping (P+D) controller with the difference that it takes into account the actuator saturation at the outset of control design and alters the proportional term by passing it through a nonlinear function; thus, we call the proposed method as nonlinear proportional plus damping (nP+D). The asymptotic stability of the closed-loop system is established using a Lyapunov-Krasovskii functional under conditions on the controller parameters, the actuator saturation characteristics, and the maximum values of the time-varying time delays. To show the effectiveness of the proposed method, it is simulated on a variable-delay teleoperation system comprising a pair of planar 2-DOF robots subjected to actuator saturation. Furthermore, the controller is experimentally validated on a pair of 3-DOF PHANToM Premium 1.5A robots, which have limited actuation capacity, that form a teleoperation system with a varying-delay communication channel. © 2013 Elsevier Ltd. All rights reserved.