Abstract: In order to make the invasive surgery more successful and more safe, a guiding robot is developed to control the active catheter in the invasive surgery. It moves in the manner of a snake utilizing a multi-joint mechanism driven by several shape memory alloy (SMA) actuators. In view of the mechanism and principle of the guiding robot driven by SMA actuators, a method to estimate the measure parameters of the bias spring is presented. At the same time, the kinematics analysis of the guiding robot is also accomplished by using the large deflection theory. Precondition of the known bending angle and orientation of the guiding robot, the SMA actuators’ displacement and output force are deduced via integral transform and the accurate coordinates of the center in the guiding robot’s front are gotten. Furthermore, the expressions for the calculation on the dimension parameters of the SMA actuators are deduced together with an integrated design theory for the guiding robot. A guiding robot prototype is designed by using the theory presented. With the help of a vascular model, the guiding robot-based invasive surgery is simulated. The research results provide integrated mathematic model for the design and analysis of the guiding robot and also perfect the design method and theory.

Key words: Active catheter, Large deflection theory, Minimally invasive surgery, Shape memory alloy