A stiffness control method for a cable-driven continuum robot with spring backbones

Abstract

Various types of robotic manipulators have been utilized to assist human beings in performing different tasks. Along with the developments in robotics, more challenging tasks are expected to be accomplished such as exploration through nonlinear paths and manipulation in confined spaces, where conventional rigid robots are no longer capable. Therefore, inspired by biological systems such as snakes, octopus and elephant trunks, various continuum robots have been developed. Due to the flexible and continuous structure of the continuum robots, the modelling of robot configuration in loaded conditions is more difficult than the conventional robots. Therefore, the control over robot interaction to the environment remains a challenge in the current state of art. In this thesis, the author proposes an equilibrium-based stiffness control method for a cable-driven continuum robot with spring backbones. The method utilizes the robot position inputs to calculate the desired actuation forces. By controlling the actuation forces, the resultant manipulation force is achieved based on the equilibrium conditions. The proposed method is implemented in simulations via MATLAB/Simulink and the results are analysed. The significances of the proposed framework include the novelty for control of continuum robots with variable backbone lengths, the utilization of marker positions to determine the robot configurations to eliminates limitations of the sensorial technology, and the capability of further extension to other direct force control methods.