Comfort accounts for fit, weight, and cushioning. Safety accounts for ground reaction force, fit, weight, and stability. Comfort is defined as the ability of the cushioning material to deform and conform to body shape so that pressure concentration is avoided and can be measured using Support Factor, which is equal to (65%IFD / 25% IFD). Indentation Force Deflection (IFD) is a measure of the load bearing capacity or the firmness. IFD is generally measured as 25%IFD and 65% IFD. X% IFD refers to the load required to compress the test sample by X% of its original thickness. For example, 25% IFD is the load required to compress say, a 40mm thick test sample to 30 mm thickness. The higher the 25%IFD, the firmer the surface feels. High 25% IFD values indicate a stiff or board-like surface. Low-density foams will have low 65% IFD values and hence will tend to bottom-out and will not support the load. High 65% IFD values on the other hand, resist bottoming-out of the foam14. So the higher the Support Factor, the more comfortable the shoe is. The safety and ergonomics of the shoe is determined according to the US F2913-11 standard15. This device shall be reusable and have the capacity to be used daily. It should be able to be used daily for up to 16 hours/day for up to six months. This amount of time was chosen because it is said that running shoes should be retired after use over 300 to 500 …show more content…
The system first and foremost must be reliable. As one of the most commonly identified user need, reliability and accuracy are critical for a successful project. One differentiator between this product and products on the market is its longevity. Without needing to be frequently recharged, this product can be seamlessly integrated into the user’s life as long as the parts do not require maintenance. To accomplish this, the processing and communication systems must be both well-protected and well-connected. For protection, there shall be a protective case containing the processing and communication systems that is able to withstand up to 220lbs. It shall function within the expected error under such forces. Finally, the computer components of the system shall be power-efficient so that the system runs for at least six months. When not transmitting, the processor shall be in an idle mode that uses very little