Design and Development of Bipedal Hopping Robot

Abstract

Legged robots represent a class of ground robots that make use of articulated linkages to move about. In juxtaposition to wheeled robots, legged robots can exploit discontinuous pathways and isolated footholds, thereby increasing their reachability. Legged locomotion in animals is also highly energy efficient in addition to being dexterous and agile. Legged locomotion is fundamentally periodic in nature with well-defined flight and stance phases in each gait cycle; this cyclic nature is exploited to increase energy efficiency in all legged creatures. These advantages make legged locomotion and design of legged robots an interesting field with promising benefits. In this report, a bipedal legged robot based on the hind legs of Felidae family (cats, cheetahs, pumas etc.) is presented with a focus on energy recovery through springs attached at bioinspired locations distal to the knee, representing various energy storage elements in animals. A robust mechanical assembly with serial leg linkages is designed and structurally analyzed for reduced mass and leg inertia. Several motor placements have been qualitatively studied in the design phase and their merits and demerits are evaluated based on design goals. In the initial stages after manufacturing, experiments on constrained hopping-in-place motion were investigated and the effects of springs observed on energy recovery and efficiency. Several open and closed loop actuation strategies were also developed and observed in practice. Experiments may be further extended to study the effects of springs on unconstrained planar walking (in the sagittal plane) and running motion in addition to study of the influence of passive dynamics dictated by the leg design on static and dynamic stability