Dynamics of Tendon Actuated Continuum Robots by Cosserat Rod Theory

Abstract

Continuum robots bio-inspired from elephant trunk or snake are widely researched due to its curvilinear path following capabilities in restricted environment. Tendon actuation is one of the direct approaches to bend such continuous structures with high force generation ability. This paper focuses on developing kinematic and dynamic model for tendon actuated robot based on cosserat rod theory with piecewise constant curvature method. Representing rotational configuration of such robots using quaternions instead of traditional Euler angles eliminates singularity in modeling and ensures unique positioning of end effector even for large relative rotations. The actuation model developed incorporates general loading on element with piecewise constant curvature and is applicable for robots with any number of discs, tendons and configuration of tendons. This model accurately predicts bending, torsion, shear and extension of robot which is validated with standard benchmark problems of two, three dimensional co-rotational as well as curved beams subjected to nonlinear external load.