Unobtrusive integration of magnetic generator systems into common footwear

Abstract

A power generating system was designed to passively harness some of the kinetic energy available during walking. The system included a rotary arm extending down from the sole, which ultimately drove a pair of small electrical generators through a stepped-up gearbox. A one-way clutch mechanism was used to transmit torque to the gearbox. This allowed for additional spin following the initial impact of a step, also preventing lockup due to rotary inertia in the gears. The entire generator system was designed to fit in the heel of a standard running shoe, with the rotary arm compressing once during each heel strike. The final system produced a peak power of 1.61 Watts during the heel strike and an average power of 58.1 mW across the entire gait. To maximize power transfer, an ideal load was determined for the two DC generators connected in series. While the average power generated was below the desired 250 mW, initial calculations show this level can eventually be reached or exceeded with the addition of a flywheel to each generator shaft, or a spring to store more energy from the heel-strike.