Hydraulically-actuated compliant revolute joint for medical robotic systems based on multimaterial additive manufacturing

In this paper, an active compliant revolute joint actuated by hydraulic energy is developed. The joint is made of polymer for integration in medical robotic systems, even in a challenging environment such as Magnetic Resonance Imaging (MRI). The use of multimaterial additive manufacturing allows us to develop two original aspects. First, a new seal design is proposed to build miniature hydraulic cylinders embedded in the active joint, with low level of friction. Second, a rack-and-pinion mechanism is being integrated to a compliant revolute joint to obtain a high level of compactness. Design and experimental assessment of the hydraulic cylinder and the compliant joint with embedded rack-and-pinion are presented, as well as an illustration in the context of needle manipulation with passive teleoperation.