Tendon-Driven Detachable End-Effector Mechanism for Minimally Invasive Surgery (MIS) Instruments

Innovation in minimally invasive surgical technologies can have a substantial increase in the number of surgeries performed and the patient outcome. Based on the survey done among 100 laparoscopic surgeons throughout India, the need for highly articulated surgical instruments for laparoscopy was put forth irrespective of the experience of the surgeon. The present innovation is directed toward an end-effector mechanism that provides the wristed motion with no singularity in roll, pitch, and yaw. Besides, the end-effector is detachable, making it interchangeable and cost lowering. To obtain the desired yaw and pitch motions, various concepts were analyzed, and the best mechanism in terms of manufacturability, innovation potential, and various design constraints was selected to be tendon-driven rolling joint end-effector mechanism. In this mechanism, each disk is configured to rotate in at least one degree of freedom or DoF for each neighboring disk, which gives either yaw or pitch motion. To control the movements of the disk elements, actuation cables or tendon elements are used to manipulate the end-effector. Each link is in contact with the neighboring disk with a revolute joint. The kinematic model is developed for the novel end-effector using the D-H parameter convention to get the position and orientation of the tip in the fixed reference frame. The end-effector is characterized in terms of instrument workspace and surgical workspace, which is compared with the existing instrument workspace using MATLAB.