Behavior and Adaptability of a Six-Legged Walking System with Highly Distributed Control

Abstract

A situated, moderately complex kinematic system—here an 18-degree-of-freedom six-legged walking system—can show a variety of behaviors, even when controlled by a relatively simple controller. Therefore, a detailed quantitative study of the behavior of such a system is necessary to achieve an understanding of its properties. This “artificial ethology” is applied to a controller with a decentralized structure that uses essential design characteristics of its biological model, the stick insect. The system takes advantage of recurrent connections that establish a loop through the environment. Despite its completely reactive nature, the system can adapt to unpredictable external conditions with no need for specific reprogramming. Leg trajectories are always adapted such that mechanical stress is reduced. This even holds true for special situations like, for example, walking over obstacles, stumbling, or walking with partially or totally amputated legs. Similarities and important discrepancies between the model's behavior and the walking behavior of stick insects are discussed.