Development of Pneumatically Driven Tensegrity Manipulator without Mechanical Springs

This paper reports a tensegrity manipulator driven by 40 pneumatic cylinders without mechanical springs. In general, tensegrity robots use mechanical springs to achieve a stable/curved tensegrity structure, and this is true even when a component extends/retracts with an actuator. The stiffness of the mechanical spring should be high to increase the stiffness of the entire structure and improve the control response, but low to deform the structure. This fact means that the introduction of mechanical springs causes serious trade-offs in its design and control. In this study, we use pneumatic actuators not only for active deformation but also for passive. In this paper, we introduce the design and control system and then show the difference in response characteristics between the case with and without a spring, demonstrating the importance of the approach without a mechanical spring.