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UBC Theses and Dissertations

Haptic teleoperation with impedance control based on learned inverse dynamics with application in homecare robotics Tufail, Muhammad

Abstract

Bilateral teleoperation allows a human operator to interact with a remote environment using the superior actuation and sensing skills of a robot and the unmatched cognitive skills of a human operator. It has shown promising results in applications such as telemedicine, telesurgery, and access to hazardous or remote environments. In all of these applications, the robot has to co-exist with humans and other delicate objects in the environment and therefore has to behave in a compliant (“soft”) manner. Moreover, in order to improve the task performance, the interaction force must be fed back to the operator to feel. In this backdrop, the present thesis focuses on the application of bilateral teleoperation in a homecare environment. In view of the underlying challenges involved with bilateral teleoperation, this dissertation focuses on the development of a complete teleoperation system that can effectively perform in real-time. A primary objective here is to use the impedance control approach to design local controllers for master and slave manipulators where the dynamic relationship between the applied forces and the resulting positions of the manipulators during interaction, is controlled. Impedance control requires the identification of the robot inverse dynamic model that can be computed in real-time and can adapt to changes in the actual dynamics of the robot. A complete data-driven learning-based technique called Locally Weighted Projection Regression (LWPR) is therefore used, which does not assume any a-priori knowledge of the inertial parameters of the robot. Performance of the system is improved by using online estimation of impedance of the unknown environment with which the slave manipulator interacts. A method of admittance control is designed. This method overcomes the shortcomings of the standard impedance control, as observed during experimentation. In the end, a method is developed to improve the transparency and position synchronization of the popular approach of wave-variables, which ensures stability under time delay that is induced by the communication channel during the exchange of information between the master and the slave ends. The effectiveness of the present developments is validated in an environment of homecare robotics, through simulation and experimentation, and the results are discussed.

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License

Attribution-NonCommercial-NoDerivs 2.5 Canada

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