Design of a superelastic alloy actuator for a minimally invasive surgical manipulator

Abstract

The purpose of this research is to investigate and develop actuators for a minimally invasive surgical manipulator using a Superelastic Alloy (SEA) as the active element. The actuator, an SEA tube, is designed to take advantage of the transformational psuedoelasticity property found in near equiatomic Ni-Ti alloys. The characteristics of SEA as an actuator are illustrated, with an emphasis on the concept of temperature dependency of stress and strain. This concept is used to develop a theory to control the motion of the individual active elements. With an elevation of temperature comes a change in the resistance that is repeatable but not completely explained to date. This change provides an ideal way to measure temperature for feedback by indirectly measuring resistance. Our design will integrate a series of actuators and a structural skeleton into a manipulator that is intrinsically simple, capable of exerting large forces, compact in size and extremely dexterous.