This paper reports the evaluation, optimization, and verification of five different design proposals for the wrist system of a new microsurgery robot. The robot targets three main types of Ear Nose and Throat (ENT) surgeries. These surgeries require a compact design and configuration synthesis to decrease collisions, provide high precision and stiffness, and accommodate the clinical requirements of each surgery type. The system is composed of two 6 DOF active robots, each composed of a 3 DOF linear stage and a 3 DOF rotary wrist mechanism. The linear stage uses a 3 DOF parallel design to increase the accuracy and stiffness of the whole system while minimizing size and weight. However, to remain compact, this parallel mechanism introduces the problem of limited linear range of motion.
Five different kinematic arrangements have been considered, and the evaluation and optimization of these configurations is discussed in detail. The main parameters considered in the evaluation include the range of motion of each DOF, the required linear movement to implement a virtual remote center of motion (RCM), and the environment occupation near the surgical tool. The optimal design of the wrist mechanism was determined by evaluating each design with respect to these parameters, and comparing the results.
A prototype of the resulting optimal kinematic arrangement was mounted on a 3 DOF linear robot to verify the results of this optimization process. A series of verification experiments was performed. These experiments successfully verified the validity of the selected design.