We’ve seen Pavegen’s energy-harvesting tiles turning up in a variety of places to harvest some of the kinetic energy generated while walking or running over them. But a team of students at Rice University has put the shoe on the other foot with PediPower – a prototype device that attaches to a shoe to harvest energy generated when the heel hits the ground.
Challenged by Houston-based company Cameron International to create a device that harvests energy from human activity, a Rice engineering student team calling themselves the “Agitation Squad” decided to create a shoe-mounted generator. After studying the force distribution across the bottom of the foot resulting from each footfall, they decided to focus on the heel. This is because, unless running, the heel is the first part of the foot to make contact with the ground, and gravity does much of the work.
The PediPower prototype devices feature an arm attached around the heel of the shoe that hits the ground first and levers up as the foot comes down. The arm is attached to a gearbox so that with every step, the gears turn slightly to drive a motor mounted on the side of the shoe. This generates electricity that is sent through wires via a voltage regulator to a belt-mounted battery pack.
Benchtop tests have seen the prototypes yield an average of 400 milliwatts, with slightly less power generated in actual walking tests because the lever arm doesn’t travel as far. The team is considering ways to maximize the potential foot power of the device, with harvesting energy from the ball of the foot as well as the heel one possibility.
In their current form, the prototype devices are too big and unwieldy for general day-to-day wear, but the team is expecting another group of students to pick up the project later in the year. It is hoped they will be able to refine the prototype, shrinking the size while increasing the power output.
The team’s hope is that eventually PediPower will be released as a commercial product to provide power to mobile phones and other portable devices. However, with Cameron International working with the Texas Heart Institute on a new generation of artificial heart pumps, the students hope their work could also find applications there.
The “Agitation Squad” gives an overview of the PediPower device in the following video.
Source: Rice University