Design Strategy for a Surgical Manipulator based on a Compliant Mechanism : Rigidity and Range of Motion: Finding the Optimized Balance Compliant mechanisms have drawn the attention recently in developing surgical robotic manipulators for minimally invasive surgery (MIS) owing to their capabilities in making miniaturized, simple, dexterous mechanical structures. Robotically assisted MIS demands instruments with higher precision, higher output force and a higher range of motion (ROM) for better performances. On the other hand, because of the behaviour of the elastic elements, compromising these factors is challenging. In a compliant mechanism, the rigidity of the elastic element determines the precision and output force. In this paper, we study the behaviour of rigidity and the ROM of elastic elements using previously developed surgical robotic forceps based on a compliant mechanism. To tackle this problem, we studied the variation of ROM of the compliant mechanism at different rigidity values of the compliant structure by changing its thickness. The results showed the linear relationship between the ROM and the rigidity of a compliant mechanical manipulator, suggesting the optimized balance point in this tradeoff.

Closed Loop Control of a Continuum Surgical Manipulator for Improved Absolute Positioning Accuracy Robotic assistance in MIS (Minimally Invasive Surgery) has attracted worldwide attention in the past decades. Even though majority of the implemented robotic surgical manipulators have articulated structures, continuum structures have been more widely applied due to their advantages of intraabdominal dexterity and safe interaction with anatomy. However, absolute positioning accuracy of a continuum surgical manipulator can be low due to its nonlinear bending behaviors under different loads and unmodeled manufacturing clearance. This paper hence presents a proofofconcept investigation of closed loop control scheme for improving the manipulatorxe2x80x99s absolute positioning accuracy. System descriptions, kinematics modeling and experimental validations are reported in detail to demonstrate the effectiveness of the proposed control scheme.