Abstracts Engineering

Control of running in a quadruped robot with actuation only at the hips

by Joseph Sarkis

Over the last few decades, much research effort has been focused on legged robots to mimic human or animal behaviors. The main motivation for this research is the fact that the majority of the earth's land mass is inaccessible to wheeled vehicles. It is therefore necessary to develop robots which can deal with a variety of terrain and overcome obstacles – legged locomotion seems to be the answer. With a new class of four-legged robots – the SCOUT class – maximum mechanical simplicity is achieved with only one actuated degree of freedom per leg. This platform with stiff legs has already been proven by Anca Cocosco to be capable of stable walking with a set of control algorithms based on controlled momentum transfer. By adding compliance in the legs and changing the control strategy to one that resembles Raibert's three-part controller, it has become possible to achieve running gaits in SCOUT-I and SCOUT-II. This will be demonstrated through simulations using the Working Model [8] software package. This thesis demonstrates that with a very simple mechanical design, simple control strategy, and only one actuated degree of freedom per leg, stable running is possible in SCOUT-II, and this for a variety of speeds and under different initial conditions. This research, along with other research on walking and stair-climbing presently being conducted at the Ambulatory Robotics Laboratory, will pave the way for robots that are inexpensive and of simple mechanical design, yet highly mobile and functional.