A Tensegrity-Inspired Compliant 3-DOF Compliant Joint

Our Tensegrity-Inspired Compliant Three degree-of-freedom (DOF) robotic joint adds omnidirectional compliance to robotic limbs while reducing sprung mass through base mounted actuation. This enables a robotic limb which is safer to operate alongside humans and fragile equipment while still capable of generating quick movements and large forces if required. Unlike many other soft robotic systems which leverage continuously soft materials, our joint is simpler to model with low order dynamic systems and has a host of embedded sensing which provide ample information of its position and velocity. We first discuss geometry selection and optimization to maximize the theoretical configuration space of the joint. We then show several of our mechatronic design solutions, which are easily generalized to a multitude of cable-driven mechanisms, and demonstrate the performance of these mechanisms within the context of our hardware prototype. We then present results on the controllable stiffness of our physical prototype. Finally, we demonstrate the strength of our prototype which is capable of lifting a 7 kg mass at a distance of 0.95 meters from the joint.