A Small-Scale Untethered Tensegrity Robot With High Velocity and Multi Locomotion Modes

Tensegrity mobile robots are well-appraised for their high stiffness-to-mass ratio and superior structural compliance. However, traditional untethered tensegrity mobile robots usually have low velocity due to the large actuation force required by coupling effects among stiff struts and soft cables. This also leads to the drawback of bulky volume and heavy mass of the robots. In addition, the existing tensegrity mobile robots have very limited locomotion modes, resulting in weak multi-terrain adaptability of the robots. In this letter, we report a small-scale untethered tensegrity robot with high velocity and multi-locomotion modes. Clustered tensegrity structure and modular concept are adopted to design the tensegrity robot, which endows the robot to achieve high velocity multi-locomotion within a small scale (length, 11 cm; width, 9 cm; height, 5.5 cm for each module) and light weight (160 g for each module). In order to analysis kinematic characteristics of different locomotion modes of the robot quantitatively, kinematic modelling is conducted, and driving laws of motors and displacements (and velocities) of the robot can be obtained theoretically. On this basis, a prototype is manufactured, and experimental results show that the robot can achieve a velocity up to 222.1 BL/min, which is the smallest and fastest untethered tensegrity mobile robot reported so far. Meanwhile, our tensegrity robot is demonstrated to achieve five locomotion modes effectively in terms of earthworm-like, inchworm-like, tumbling, rolling and hybrid locomotion, and can be used in multi-terrain environments benefit from the multi-locomotion modes.