Development of a Bipedal Hopping Robot With Morphable Inertial Tail for Agile Locomotion

Abstract

Animals often use their external appendages (such as tails, limbs) to achieve spectacular maneuverability, energy efficient locomotion, and robust stabilization to large perturbations, which may not be easily attained in the existing legged robots. Their appendages, particularly, the tails are very compact, light, highly dexterous with a large range of motion (RoM). Animals can also curl and straighten up their tails in less than one-tenth of a second to facilitate rapid adjustment for the moment of inertia (IoM) and the center of mass (CoM). Most of the existing robotic tail designs still lack dexterity, output force, dynamic response as compared to their biological counterparts. The objective of this research is to create a viable and compact solution to adjust the tail IoM rapidly and effectively for the enhancement of robot agility. We design and build a novel 3-DoF morphable inertial tail based on a spherical linkage mechanism, incorporated with a spring-load telescopic tube to realize a wider range of inertial adjustment ability. We also develop a dynamic model and propose motion controllers to study the tail-inspired dynamic locomotion. Simulation and initial experimental results demonstrate the effectiveness of the proposed mechanical design and controllers to enhance more agile locomotion using the swinging tail.