How do the compliant legs affect walking stability

Abstract

The dynamics of walking can be achieved by using the compliant legs. Understanding the compliant mechanisms during walking would improve the design of assistive devices for humans. We studied how and the extent to which the compliant legs would affect the passive stability of walking. From the biomechanics of human walking, we built three 2D models with compliant legs of different leg structures. The three models had the same performance during constant-average-speed walking. We then perturbed these models by changing the elevation of the ground. We found that the compliant legs from different structures provided passive stability to resist perturbation from the ground. The SLIP model can maintain stability in a broader range of perturbation magnitude than the SSEG or STSM. By splicing legs from pure models with two identical legs to create hybrid models, we found the passive stability of hybrid models can be inherited from the pure models. The mechanical properties of the leg properties hence determine the passive stability. Understanding the passive stability from the compliant mechanism of legged locomotion helps to improve the design and control of powered prostheses and legged robots.