Task-specific evaluation of kinematic designs for instruments in minimally invasive robotic surgery

In minimally invasive robotic surgery, slender instruments are used that provide additional degrees of freedom inside the human body. Kinematic limitations due to the instrument could endanger the secure execution of a surgical task. Numerous design alternatives are proposed in literature whereas few work is done that evaluates the performance of these instruments objectively. This paper presents a new method to evaluate alternative designs of instrument kinematics with respect to their ability to perform surgical tasks. Two specific criteria are set up accounting for the limited space during a minimally invasive intervention as well as for the ability to execute the desired task. The evaluation is based on task specific reference trajectories which are recorded in one orientation. During robotic surgery, arbitrary orientations of this area can occur. The method is able to handle this by rotating the acquired reference trajectories within software. The presented method is independent from the setup, i.e. the relative position and orientation of the area of interest with respect to the trocar location. Four different examples demonstrate the application of the method to show its usefulness.