Development of anti-twist mechanism for continuum manipulator and modeling focusing on bending stiffness

Abstract

This paper proposes a new mechanism and a modeling method for continuum manipulators. The new mechanism is an anti-twist mechanism. Continuum manipulators have the merit of flexibility. However flexibility causes unexpected motions such as twisting under heavy loads. The proposed mechanism avoids only twist motion without affecting the other two bending motions. The mechanism is composed of 3 plastic parts. The effect of the proposed mechanism is verified by the experiments. The modeling method for continuum manipulators are used for inverse kinematics. It will make the motion of the tip more precise. Continuum manipulator has a nonlinear relationship between the input wire length and output manipulator configuration. A new model which uses minimum total potential energy principle is proposed. The validity of the proposed model is examined by comparison of the experimental results while the bending stiffness is changed. Both proposed new mechanism and model will make the continuum manipulator motion better.