High-Performance Continuous Hydraulic Motor for MR Safe Robotic Teleoperation

Magnetic resonance imaging (MRI) guided intervention has drawn increasing attention over the last decade. It is accredited to the capability of monitoring any physiological change of soft tissue with the high-contrast MR images. This also gives rise to the demand for precise tele-manipulation of interventional instruments. However, there is still lack of choices of MR safe actuators that provide high-fidelity robot manipulation. In this letter, we present a three-cylinder hydraulic motor using rolling-diaphragm-sealed cylinders, which can provide continuous bidirectional rotation with unlimited range. Both kinematics and dynamics models of the presented motor were studied, which facilitate its overall design optimization and position/torque control. Motor performance, such as step response, frequency response, and accuracy, were experimentally evaluated. We also integrate the motor into our catheter robot prototype designed for intra-operative MRI-guided cardiac electrophysiology (EP), which can provide full degree-of-freedom and precise manipulation of a standard EP catheter.