Kinematic Analysis in Robot Assisted Femur Fracture Reduction: Fuzzy Logic Approach

Abstract

Femur fracture is a frequently occurred injury and usually treated by surgeries. In order to overcome problems involved in the surgeries and improve the surgical operation efficiency, researches on automated or semi-automated robot-assisted surgery have been carried out, but very few literatures have reported the realigning motion planning of bone fragment, like velocity planning and acceleration planning. Fuzzy logic, using linguistic rules to manipulate and implement human knowledge, is deemed as an efficient approach to deal with large variability and overcome difficulties of modeling complex environment that is difficult to express using mathematical equations. In this paper, bone fragment is reconstructed based on CT images. Two fuzzy logic controllers are proposed to deal with acceleration planning. The controllers use linguistic rules to coordinate the inputs about obstacles, such as soft tissues, nerves and arteries, so that acceleration for bone fragment reduction can be obtained. Fuzzy controller one evaluates risk of trauma that is induced by bone fragment motion and fuzzy controller two computes acceleration based on the risk of trauma and reduction path. Velocity is computed according to the acceleration. Simulation results have shown that the risk of trauma increases when the bone segment is approaching obstacles, and at the same time, bone fragment velocity reduces smoothly. This is exactly what is desired in bone fragment reduction.