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Nonlinear Bilateral Adaptive Impedance Control with Applications in Medical Robotics

Sharifi, Mojtaba | 2016

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 49184 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Salarieh, Hassan; Behzadipour, Saeed; Tavakoli, Mahdi
  7. Abstract:
  8. In recent years, teleoperation systems have been widely used in bio-medical applications such as minimally invasive telesurgery, telerehabilitation and telesonography, and also for outer space exploration and radioactive material management. In bilateral teleoperation systems, the human operator applies force on the master robot to control the position of the slave robot in order to perform a task in a remote environment. A nonlinear robust adaptive bilateral impedance control strategy is proposed in this research to provide the absolute stability of multi-DOF teleoperation systems with communication delays. Using this controller, instead of conventional position tracking (synchronization) and force tracking (force reflection) performances, certain impedances in the nonlinear teleoperation systems are controlled. Also, it is shown that the proposed bilateral impedance controller guarantees the teleoperation system’s absolute stability in the presence of constant time delays in addition to the force and position tracking performance. This is important because previous nonlinear adaptive bilateral controllers for multi-DOF teleoperation systems, with the position and force tracking objectives, did not guarantee the absolute stability when time delays were included in the communication channel. The proposed controller realizes two desired (or reference) impedance models for the master and slave robots using a new nonlinear robust version of the Model Reference Adaptive Control (MRAC) scheme. In addition, using the Lyapunov stability theorem, the tracking performance of the master and slave robots and the robustness of the proposed controller against parametric and bounded unstructured modeling (non-parametric) uncertainties are proven. The performance of the proposed nonlinear bilateral controller is investigated by performing some experiments on nonlinear multi-DOF telerobots in soft and hard contact scenarios with and without communication delays. The proposed bilateral control strategy is employed in different applications of medical robotics. Four scenarios of the tele-rehabilitation for patients with disabilities, the tele-surgery of beating-heart and the tele-echography of moving organs are experimentally tested using this bilateral impedance controller. It is shown that previous force-position controllers cannot (or can hardly) be used in some cases of the above-mentioned medical applications. However, by different adjustments of the impedance models in the proposed strategy can achieve the desired objectives in different applications. Finally, the proposed controller is extended for trilateral systems to provide a cooperation between two human operators (interacting with two master robots) in order to perform a task by the slave robot on the environment. Thus, the trilateral nonlinear version of the Model Reference Adaptive Impedance Control (MRAIC) scheme is developed. The applications of this trilateral teleoperation system are the robotic surgey with two (e.g. experienced and amateur) surgeons, two-handed surgery and mirror therapy of the disabled limb using the healthy limb of the patient
  9. Keywords:
  10. Model Reference Adaptive Control ; Teleoperation System ; Lyapunov Stability ; Absolute Stability ; Robotic Telesurgery ; Bilateral Adoptive Impedance Control ; Tele-rehabilitation ; Tele-sonography

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