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UBC Theses and Dissertations

On the development of a heart motion compensation system on the da Vinci research kit for minimally invasive surgery on the beating heart Ruszkowski, Angelica

Abstract

This thesis describes the development of a heart motion compensation system on the da Vinci Research Kit for coronary artery bypass surgery. With this teleoperation robotic platform, minimally invasive surgery on a beating heart could be performed on an already clinically prevalent system. Semi-automation of the slave manipulators of the robot is introduced as they track the surface of the beating heart. The surgeons' regular teleoperation commands are superimposed on the automated trajectory. To achieve a virtually stabilized environment, a novel concept of maintaining the camera fixed relative to the heart target is proposed. The preliminary research question is whether the robot is capable of tracking the highly dynamic heart motion. System identification was performed on the seven degree of freedom da Vinci slave manipulators, and an open loop controller was developed. The controller is based on spectral line decomposition and the assumption of a periodic trajectory. It successfully commanded the slave manipulators to track an actual three dimensional heart trajectory with submillimetre error. Experiments were conducted with expert robotic users to evaluate surgeons’ ability to perform tasks on a moving target emulating the beating heart, with very promising outcomes. The number of missed targets decreased from 37% to 13% when compensation was enabled, the number of hit targets increased from 26% to 41%, and completion time decreased. A second generation system was developed which includes real time motion measurement commanding the robot. Results from user studies with expert surgeons performing bimanual suturing on moving targets with the new system support the motion compensation. They also show the significance of motion measurement errors. As an added safety, a virtual fixture was implemented to protect the heart from accidental collisions with the instrument tips. User studies were conducted to validate the efficacy of the fixture. To expedite controller development, an interface was developed between Matlab Simulink and the C++ code that runs the da Vinci Research Kit. This allows on-the-fly testing of controllers which could be designed and developed in the convenient Simulink environment. Future work will be include closed loop control, improved experiment design, and the incorporation of electrocardiogram signals.

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Attribution-NonCommercial-NoDerivs 2.5 Canada

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