Fully interconnected, linear control for limit cycle walking

Limit cycle walkers are a class of bipeds that achieve stable locomotion without enforcing full controllability throughout the gait cycle. Although limit cycle walkers produce more natural-looking and efficient gaits than bipeds that are based on other control principles such as zero moment point walking, they cannot yet achieve the stability and versatility of human locomotion. One open question is the degree of complexity required in the control algorithm to ensure reliable terrain adaptation and disturbance rejection. The present study applies a fully interconnected, linear controller to a two-dimensional, five-link walking model, achieving stable and efficient locomotion over unpredictable terrain (slopes varying between 2° and 7° and step-downs varying between 0 and 25% leg length). The results indicate that elaborate control principles are not necessarily required for stable bipedal walking.