Six-DoF Pose Estimation for a Tendon-Driven Continuum Mechanism Without a Deformation Model

Abstract

In recent years, the application of continuum mech- anisms increased as they provide high dexterity, consume a low amount of space, and handle unforeseen collisions with ease. Typi- cally, a deformation model of the continuum is applied to compute task space poses from actuator variables. However, simple models usually lack accuracy, whereas accurate models are computation- ally demanding. This letter deals with the pose estimation problem for a continuum mechanism based on length sensors without using a deformation model. A subset of the sensors belongs to the actuating tendons with a fixed routing, whereas the rest of the length sensors can be placed freely. Two major issues are discussed. At first, a sensor placement strategy based on the coupling matrix is derived and discussed, which improves the observability for static pose estimation. Second, the feasibility of a sensor fusion between an inertial measurement unit and the length sensors to enhance the pose estimation is presented. Both investigations are done experi- mentally on DAVID. By placing the additional sensors correctly, the maximum estimation error can be lowered by 50% in comparison to poorly placed sensors.