Stability of Bilateral Teleoperation Systems: Effect of Sampled-data Control and Non-passivity or Strict-Passivity of Terminations

• Author / Creator

  Jazayeri Moghadas, Seyed Ali

• A bilateral teleoperation system comprises a human operator, a teleoperator, and an environment. The teleoperator consists of a master, a slave, their controllers, and a communication channel. Since the models of the terminations namely the human operator and the environment are unknown and/or time-varying, passivity or absolute stability of the teleoperator is considered for ensuring the stability. This stability analysis typically relies on two assumptions: (a) the system is continuous-time, and (b) the terminations are passive. This dissertation studies the stability implications of violation of either assumption.

  The stability of a bilateral teleoperation system may be jeopardized by controller discretization due to energy-distilling effects of a zero-order-hold. In this dissertation, a tool is developed to analyze the passivity of the sampled-data teleoperator. In the passivity framework, the teleoperation system is guaranteed to be passive and, therefore, stable for any passive and otherwise arbitrary terminations. Sufficient conditions for teleoperator passivity are derived when teleoperation controllers operate in discrete-time. The criterion is verified through simulations and experiments.

  A less conservative approach to guaranteeing the coupled system's stability is teleoperator's absolute stability. This dissertation proposes a novel approach to analyzing the absolute stability of a bilateral teleoperation system consisting of discrete-time controllers and continuous-time master, slave, operator, and environment. The resulting condition has been verified via experiments.

  In the passivity and absolute stability analyses, the exact models for the teleoperator's terminations are not available. To make the stability analysis independent of the termination models, it is typically assumed that they are passive but otherwise arbitrary. However, the assumption of passivity of the terminations is less than accurate and may be violated in practice. Using Mobius transformations, we develop a new stability analysis tool for investigating the stability of a two-port network when coupled to an input strictly-passive, an output strictly-passive, an input non-passive, or a disc-like non-passive termination. Simulations and experiments are reported.

• Subjects / Keywords

  • Strict-passivity
  • Bilateral Teleoperation Systems
  • Stability of Teleoperation
  • Non-passivity
  • Absolute Stability
  • Discrete-time Control
  • Sampled-data Control
  • Teleoperation Passivity

• Graduation date

  Fall 2013

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R37M0466G

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.