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Lookup NU author(s): Dr Michael Lau
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Nonlinear friction in tendon-sheath mechanism (TSM) introduces difficulties in predicting the end-effector force inside the human body during surgical procedures. This brings a critical challenge for surgical robots that need high fidelity in haptic devices. This paper presents a new friction model for a TSM in surgical robots. The model considers the TSM as an element disregarding the tendon sheath curvature and permits an arbitrary configuration of sheath. It allows for the accurate modelling of friction force at both sliding and presliding regimes. Unlike existing approaches in the literature, the model employs not only velocity but also acceleration information. It is also able to capture separate hysteresis branches in the large displacement using a unique differential equation. Transition between the two regimes is smooth. To validate the approach, an experimental setup is developed to measure the tensions at both ends of the TSM. The model parameters are identified and experimentally validated using an optimization method and different types of input signals. It assures an accurate prediction of nonlinear hysteresis behaviour of TSM, especially at near zero velocities. This model can be used to provide an estimate of the friction force in a haptic feedback device to the surgeons.
Author(s): Do TN, Tjahjowidodo T, Lau MWS, Phee SJ
Publication type: Article
Publication status: Published
Journal: Mechanism and Machine Theory
Print publication date: 01/03/2015
Online publication date: 22/11/2014
Acceptance date: 08/11/2014
ISSN (print): 0094-114X
ISSN (electronic): 1873-3999
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