Study of the energy scavenging by piezoelectric transducers on the knee during a gait

摘要

Converting the mechanical energy of human body to electrical energy became promising alternative to ensure power supply of nomadic devices. This approach has great potential innovation and respect for environmental issue and falls under the termed of renewable energy. In this work, the design and simulation of a transducer that can convert the mechanical availed energy due to knee flexion during gait cycle into electrical energy are studied. This transducer consists of bimorph piezoelectric cantilever beam with a tip mass at the end. This beam is designed to be positioned in the back side of knee to transfer the mechanical excitation due the knee flexions. Using Comsol Multiphysics, simulations were performed to expose the output power that can generate since a single transducer and two transducers although phases of walking cycle. In full stride at naturel walking speed of l m/s has a frequency of IHZ (two steps per second) the maximum power that can be stored is 36 mW from a single transducer at 10° angle of knee flexion. This value was observed decrease to 2. 5mW at loading response phase of two transducers. The level of power attained with two transducers is lower than single transducer in each angle of knee flexion. This evaluation of output energy demonstrates that energy harvesting from knee motion during walking can supply autonomous systems.