Kinematic Analysis and Design of a Six-Degrees of Freedom 3-RRPS Mechanism for Bone Reduction Surgery

Robot-assisted bone reduction surgery consists in using robots to reposition the bone fragments into their original place prior to fracture healing. This study presents the application of a 3-RRPS augmented tripod mechanism with six degrees-of-freedom for longitudinal bone reduction surgery. First, the inverse and forward kinematic models of the mechanism are investigated. Particularly, the forward kinematic is solved by applying Sylvester's dialytic method. Second, the velocity model is studied and its singular configurations are identified. The workspace of the 3-RRPS mechanism is then outlined and compared with the Stewart platform, which is a classical mechanism for the targeted application. The results show that this mechanism provides a larger workspace, especially its rotation angle about the vertical axis, which is an important aspect in the bone reduction. A series of simulations on the numerical and graphic software is performed to verify the entire analysis of the parallel mechanism. A physiguide and mscadams software are used to carry out a simulation of a real case of femur fracture reduction using the proposed mechanism to validate its suitability. Finally, a robotic prototype based on the mechanism is manufactured and experimented using an artificial bone model to evaluate the feasibility of the mechanism.