Shoe-Like Unpowered Exoskeleton With Energy Harvesting for Enhanced Walking Economy

The development of an exoskeleton to enhance walking efficiency and reduce energy consumption is crucial. However, current designs face challenges such as excessive weight, conspicuous appearance, and power constraints, limiting real-world applications. This study explored the energy conversion mechanism in gait analysis, leading to the development of a walking-phase sensing trigger combined with springs as an unpowered energy-harvesting device. This device captures and stores negative mechanical energy during walking, releasing it during the push-off phase to assist propulsion. The proposed design integrates a single-slider crank mechanism, ratchet, and springs, creating an innovative, unpowered shoe-like exoskeleton. Its shoe-like appearance enhances concealment for users. Walking experiments evaluated the exoskeleton's effectiveness under varying spring stiffness conditions. The results showed a significant 7.77%±1.49% (mean ± s.e.m.) reduction in energy expenditure when wearing the exoskeleton during level walking. Furthermore, heartbeat and plantar flexor muscle activity decreased, and no significant interferences were observed in walking similarity, step length, or frequency. In slope walking, although the assistive effect was reduced compared to level walking, the device did not increase overall physical exertion. Notably, metabolic cost and heart rate remained lower than the baseline, while muscle activity outcomes varied, with reductions observed in some muscles and increases in others. These findings support the proposed device's effectiveness on level terrain while also highlighting its limitations on inclined surfaces.