Control Strategies for a Multi-Legged Hopping Robot

This paper presents locomotion control strategies for a novel, multi-legged hopping robot named ldquorobotic all-terrain surveyorrdquo (RATS). This conceptual robot has a spherical body roughly the size of a soccer ball, with 12 legs equally distributed over its surface. The legs are linear pneumatic actuators (1-DOF), oriented such that their axes of motion are normal to the surface of the body. While the 12-legged robot is still in design, we have experimented with a planar 5-legged prototype to study the control problem in a simpler form. Our control solutions overcame the constraint that the legs are at a fixed orientation with respect to the body by inducing the body to roll. This approach allows the legs to be positioned sequentially at a desired angle with respect to the ground surface, exploiting the symmetric configuration of the system. Successful gaits for running and jumping over obstacles based on the rolling concept are presented in this work. Physical experiments with the 5-legged device validate the control approaches and demonstrate the performance of the system and its potential for the future.