Abstract-Performing surgery on fast-moving heart structures while the heart is freely beating is next to impossible. Nevertheless, the ability to do this would greatly benefit patients. By controlling a teleoperated robot to continuously follow the heart's motion, the heart can be made to appear stationary. The surgeon will then be able to operate on a seemingly stationary heart when in reality it is freely beating. The heart's motion is measured from ultrasound images and thus involves a non-negligible delay due to image acquisition and processing, estimated to be 150 ms that, if not compensated for, can cause the teleoperated robot's end-effector (i.e., the surgical tool) to collide with and puncture the heart. This research proposes the use of a Smith predictor to compensate for this time delay in calculating the reference position for the teleoperated robot. The results suggest that heart motion tracking is improved as the introduction of the Smith predictor significantly decreases the mean absolute error, which is the error in making the distance between the robot's endeffector and the heart follow the surgeon's motion, and the mean integrated square error.

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Abstract-Beating-heart surgery is not currently possible for most surgical procedures as it requires superhuman skill to manually track the heart's motion while performing a surgical task. However, if a surgical tool could track the motion of the point of interest (POI) on the heart, then, with respect to the surgical tool tip the POI would appear stationary. Such a system can be created with a teleoperated surgical robot that is controlled to track the combination of the heart's and the surgeon's motion, as input through a separate user console. To develop such a system, the motion of the heart is found in ultrasound images where the image acquisition introduces delays of approximately 40 ms and image processing further increases this delay. Directly using this delayed position measurement in the feedback control loop can lead to instability and poor tracking. The generalized predictive controller used in this work compensates for this time delay despite large disturbances with velocities up to 210 mm/s and accelerations up to 3800 mm/s 2 caused by the moving heart.

Surgery on a freely beating-heart is extremely difficult as the surgeon must perform the procedure while following the heart's fast motion. However, by controlling a teleoperated robot to continuously follow the heart's motion, the surgeon can operate on a seemingly stationary heart. The heart's motion is calculated from ultrasound images and thus involves a non-negligible delay estimated to be 100 ms that, if not compensated for, can cause the robot end-effector (i.e., the surgical tool) to collide with and puncture the heart. This research proposes the use of a Smith predictor to compensate for this time delay. The results suggest that this improves heart motion tracking as the mean absolute error, the difference between the surgeon's motion and the distance between the heart and surgical tool, and the mean integrated square error decreased.

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