Open-loop Position Controller for Tendon-driven Soft Continuum Manipulators

Abstract

Soft continuum manipulators possess exceptional capabilities for gentle and non-destructive exploration and inspection of complex environments, replicating the natural flexibility observed in living organisms. These manipulators, in combination with precise position control, prove to be ideal for delicate and high-risk environment exploration. Various actuation methods, including tendon-driven systems, are discussed in the literature. Tendon-driven actuation is preferred due to its reduced dimensions, flexible nature and ease of control. When utilizing geometric methods such as Constant Curvature (CC) models for soft robots, it is imperative to establish additional models that connect curve parameters with actuator variables. This work introduces an actuation function for multi-section tendon-driven soft robots with an open-loop position controller. This model establishes a correlation between curvature variables and tendon displacement lengths, accommodating any number of tendons per section. The proposed method demonstrates an average position error of 22.78% of the total length of the manipulator for a configuration with one actuated section employing three tendons and 20.80% for one with four tendons. In the case of a setup with two actuated sections, each section containing three and four tendons, the model exhibits an average error of 15.64%.