A comparison of three insect-inspired locomotion controllers

This paper compares three insect inspired controllers which were implemented on an autonomous hexapod robot There is a growing interest in using insect locomotion schemes to control walking robots Researchers interest in insect based controllers ranges from understanding the biological basis of locomotion control in insects Cruse Full Dean to building real time walking machines which require relatively little computational power Ferrell Donner Brooks Beer Chiel Several models for insect locomotion exist and robotics re searchers tend to adopt one approach and experiment with it In contrast this paper o ers a comparison of three insect inspired controllers all of which were implemented and tested on the same autonomous hexapod robot Some of the controllers used re ex based mechanisms whereas others used pattern based mecha nisms Re exive controllers exploit sensory stimulus and response reactions to produce leg motion and gait coordination In contrast pattern based controllers depend more upon pre programmed patterns of behavior which may be in uenced by external events Typically these pre programmed patterns of behavior are implemented using central pattern generators CPGs In this work we compare gait coordination performance of three controllers on at terrain We extend the comparison to include leg loading considerations disabled leg compensation and externally applied leg perturbations We discuss the di erences between controllers with respect to inconsistent leg retraction velocities leg design issues sensing requirements and computational issues The robot performed quite di erently under varying experimental conditions depending upon which controller was used We found that controller performance was the most sensitive to robot design parameters For our case we had the most success with pattern based mechanisms given the leg design of our robot and its limitations in controlling the retraction velocity of its legs The pattern based mechanisms allowed the robot to remain stable over a variety of gaits while the robot was subjected to loading the legs disabling a leg and physically disturbing the legs The re exive mechanisms were less successful at maintaining stability when the robot s legs were increasingly disrupted