Type synthesis of novel 1R, 2R, 1R1T, and 2R1T hybrid RCM mechanisms based on topological arrangement and modular design method

Remote center motion (RCM) mechanisms play a significant role in minimally invasive surgery (MIS) to provide geometric constraints to the surgical tool motion. To satisfy the rapid diversified development of the surgical robot in various environment, especially in the head coil, MRI room or other enclosed confined space, this paper focuses on the type synthesis of hybrid-RCM mechanisms using the topological arrangement and modular design method (TAMD). Firstly, the concepts of TAMD are proposed systematically for type synthesis of general hybrid mechanisms. Secondly, TAMD is applied towards the type synthesis of RCM mechanisms to generate their topological arrangement and motion characteristic relationships. Thirdly, main module and secondary modules are designed for RCM mechanisms of four different motions (i.e., 1R, 2R, 1R1T, and 2R1T) based on the proposed topological arrangement. Numerous novel 1R, 2R, 1R1T, and 2R1T RCM mechanisms are then proposed by assembling these main and secondary modules. Finally, one typical case for each motion of RCM mechanisms is taken as an example to validate its motion capability.