CAD Model

Included here are pictures of the 2D and 3D CAD models created for the individual components and assemblies in our project using AutoCAD and Creo Parametric 2.0:

Structure

The profile of the device is comprised of two structural components. These components, affectionately referred to as the 'Drumstick' and 'Thigh' combine at a hinge parallel to the knee, creating what is essentially an imitation of the human leg. Due to material constraints, it was decided that these portions of the device would be cut out of a polycarbonate sheet using a laser. For this reason we created the additional 2D models.

The Thigh

The Drumstick

The Completed Leg Assembly

2D Model of Leg Layers, Pawl, and Spacers

Gear Assembly

Gears are used in the design to create a favorable mechanical advantage and increase the angular velocity of the generator. To get it just right, we had to design our own gears in Creo after doing many calculations to determine the pitch angle, addendum, dedendum, depth height, etc for our gears. Additionally, we designed a pawl to drive our gears in only one direction.

A single 5:1 spur gear couple

(75 teeth on the large cylinder, 15 on the small)

4 gears lined up (3 pairings) yields a

mechanical advantage of 125:1

Updated Gears using less material

A Gear Pawl dictates the direction of motion in our gear chain

The Gear and Pawl Assembly

Generator

Our generator consists of a flywheel (containing strong magnets) spinning over top a circular plate (containing copper coils) connected with a ball bearing assembly. According to Faraday's Law of Induction, this will produce a current in the coils, powering our battery.

The Flywheel as seen from the front (shallow holes for magnets)

The Flywheel as seen from the back (shelled to reduce material cost)

The Coil Plate (deep pegged holes for copper coils, and 

a central peg for the ball bearing assembly)

The Coil Plate as seen from underneath (shelled to reduce materials cost)

Assembled Flywheel, Coil Plate, and Ball Bearing

The Whole Shebang

Fully assembled, the mechanical portion of the device is a mighty beast. Due to material constraints, the gears and generator had to be altered to use less volume. The perforations in the gears won't affect the performance since they will never be under much force, but they certainly give it a new aesthetic.