A Self-Decoupling Three-Segment Continuum Flexible Robot Based on Stiffness Difference

The coupling effect of the flexible robotic arm with multiple degrees of freedom greatly increases the control complexity. For flexible endoscopic robots that manipulate an endoscope or other necessary channels like gas detection channel, its performance, like adaptability to tortuous paths, simplicity of control, and compactness of size are essential. Currently, there is a tradeoff between multiple-degree of freedom (DOF) and control accuracy of continuum robots. In this article, a self-decoupling continuum robot with multiple stiffness was proposed. Based on the difference in stiffness among segments, the proposed robotic arm can well realize the independent operation of each DOF. Using stiffness analysis and kinematics calculation, the optimal self-decoupling structure model of the robot was determined. With finite element analysis and experimental verification, the control error of the proposed robotic arm is less than 2.5%. The coupling error among segments is less than 6.7%, and the ratio of absolute maximum error to the length of the robotic arm is less than 1.4%.