Gait Studies for a Power and Control Autonomous Legged Microrobot

Abstract

The confluence of new materials, manufacturing techniques, and small-scale electronics allows robots to not only become smaller, but also have increased degrees of freedom and functionality. One approach for the creation of new microrobots is to turn to insects, which have evolved over millions of years, to see how they excel at their small scales. Prior to this thesis, the Harvard Ambulatory MicroRobot (HAMR) was designed to be a platform inspired by legged insects that can be used for applications such as search and rescue and confined environment monitoring and exploration. Despite its small form factor (4.5 centimeters long and 1.43 grams), HAMR has four legs and eight independently actuated degrees of freedom. The result is an excellent platform to explore new designs, control architectures, and scale-effects of legged microrobots. This thesis describes many of the underlying principles for the operation of HAMR and investigates new facets of its performance. First, Chapter 2 gives an overview of small-scale legged robots, actuation, and scale effects. Chapter 3 describes the current HAMR platform used for the experiments in this thesis. Chapters 4 and 5 discuss gait evaluation, comparisons to biology, and gait selection techniques which result in speeds up to 21 body lengths per second. Chapter 6 presents a new control scheme for high speed turning, lateral maneuvers, and path following. Finally, Chapter 7 presents HAMR-F, an untethered version of HAMR that weighs only 2.79g and can perform closed-loop heading control.