A four-prism tensegrity robot using a rolling gait for locomotion

Since the twenty-first century, research on tensegrity structures has been extended from the field of architecture to robotics, considering their promising environmental adaptability and safe human-machine interactivity. Tensegrity robots usually utilize strut-cable coupled dynamics to achieve crawling or rolling movement. Whereas, when it comes to a simple structure, e.g., the Four-Prism Tensegrity Robot (FPTR), its rolling locomotion has been challenging to realize. Therefore, this paper presents a design method utilizing the structural deformation of the FPTR to achieve steerable rolling locomotion. To investigate the parameter-selection process and the possible deformation of the FPTR, kinematic, static, and dynamic models are built and relevant simulations are implemented. Then this paper proposes four basic rolling steps of the FPTR and one specific control pattern allowing for going straight and turning left/right. A robotic prototype is further developed to validate the reliability of the model and the feasibility of the FPTR's steerable rolling gait. It eventually proves that even the prismatic single-unit tensegrity robot is qualified to make use of its structural deformation to achieve controllable and steerable rolling locomotion.