A robotic case study: Optimal design for laparoscopic positioning stands

A positioning stand can help a surgeon with positioning and locking endoscopic tools, thereby avoiding the need for an assistant surgeon. The kinematic configuration of the positioning stand is comprised of two main parts: the arm (for positioning), and the wrist (for orienting the tool). The main requirement of the wrist is to perform spherical movements around the incision point. A concentric multilink spherical joint design has been developed for the wrist mechanism. The size synthesis is performed to minimize the overall size of the wrist, and also to maximize its range of angular movements. The type synthesis of the positioning arm has led to the use of a SCARA configuration as a balanced and easily moved arm configuration. The size synthesis of the arm is carried our with the goal of minimizing its overall dimensions, based on the arm's reachable workspace and manipulability. The integration of the wrist and arm is performed by optimizing the orientation of the wrist in such a way that the interference between the wrist and the workspace of the surgeon is minimized.