Abstract: This paper presents a continuum manipulator inspired by the anatomical characteristics of the elephant trunk. Specifically, the manipulator mimics the conoid profile of the elephant trunk, which helps to enhance its strength. The design features two concentric parts: inner pneumatically actuated bellows and an outer tendon-driven helical spring. The tendons control the omnidirectional bending of the manipulator, while the fusion of the pneumatic bellows with the tendon-driven spring results in an antagonistic actuation mechanism that provides the manipulator with variable stiffness and extensibility. This paper presents a new design for extensible manipulator and analyzes its stiffness and motion characteristics. Experimental results are consistent with theoretical analysis, thereby demonstrating the validity of the theoretical approach and the versatile practical mechanical properties of the continuum manipulator. The impressive extensibility and variable stiffness of the manipulator were further demonstrated by performing a pin-hole assembly task.

Key words: Bioinspired robots, Continuum robots, Soft robotics, Variable stiffness