Simulation and evaluation of a body energy harvesting device for arm and leg swing motions

Body energy harvesting (BEH), especially for wearable devices, is an emerging and promising technology to improve the battery capacity and to avoid regular maintenance in terms of energy supply. A broad application of BEH increases sustainability and thus offers an advantage from an environmental point of view. We present a light weight BEH device for non-resonant arm and leg swing motions. The design was kept as simple and robust as possible and is based on an electrical generator. The generator is moved by an oscillating mass, which was previously simulated in a model, so that in this generator model, the kinetic energy is optimally transformed into electrical energy. Additionally, an ultra-low voltage power conditioning circuit, based on a step-up converter, was adapted to the BEH generator. The BEH generator and the power conditioning circuit were evaluated in a real test setup for arm and leg movements during walking and jogging with the BEH device worn on the wrist or ankle. An effective power of ∼11.3 mW was generated. This provides a constant voltage to charge a battery or supercapacitor.