Feedback Control of a Patient-Mounted Telerobot using Electro-magnetic Tracking of Needle Angle

The Robopsy device is a lightweight, largely plastic telerobot (shown below in Fig. 1A) that affixes directly to a patient’s chest to pivot the needle in two degrees of freedom about a skin insertion point [1]. This is accomplished via two motor-actuated concentric, crossed and partially nested hoops. A medical image-based interface converts doctor clicks on the DICOM images to motor commands that align the needle along the desired trajectory and subsequently insert it. [2]. The kinematic equations to determine the motor commands to align the current needle trajectory with its desired trajectory are outlined.