Easy Grasp: A novel hybrid-driven manual medical instrument for laparoscopic surgery

A novel compact manual instrument for laparoscopic surgery, Easy Grasp, is proposed and the prototype is developed. It is a hybridization of cable and link drives. The instrument conforms to the ergonomic engineering and it can realize roll, pitch, and yaw motions. Owing to the parallelograms and universal joints, the motions outside the abdomen can be mapped to the end-effector motions inside the abdomen exactly. The workspace of the wrist-like joint is a submanifold of special orthogonal group and is evaluated by the matrix exponential parameterization. The structure of the instrument is designed optimally on the basis of the kinematic analysis together with the global condition index. The instrument can not only satisfy the needs of basic tasks, but also be used to accomplish difficult tasks such as suturing and knot-tying. Experimental results show that the instrument works as well as commercial products. The ease of use will make the instrument effective in laparoscopic surgery. The structure of the instrument is a prototype for other manual instruments and provides a framework for instrument design.