In Search of Efficient Walking Robots

With the recent conflicts in Afghanistan and Iraq, it is increasingly evident that the demands of warfare are changing and the need for innovative mobility systems is growing. In the rough, unstructured terrain that the soldiers encounter, they have reverted to using mules and donkeys to move stealthily and quickly. In light of the growing need for autonomous systems, the Army is looking at the possibility of legged mobility options such as gasoline powered quadrupeds to traverse the off-road terrain. As technology advances, the era of military bipeds may well be in sight. However, current bipedal robotic technology is far too inefficient for battlefield use. Much of this inefficiency stems from actuated control of each limb's motion throughout the entire gait cycle. An alternative approach is to exploit the passive pendular dynamics of legs and legged bodies for energy savings. This paper compares and contrasts fully-actuated walking with passive walking. Simulations of passive and quasi-passive walking are analyzed to evaluate their stability regions and their initial responses on uneven terrain functions are compared.