I continued to wear the fitbit for a second week in a row to increase the amount of data points available (and also because it has become an easy habit).
Challenge question answers:
How large is my average stride? 2 ft. 3.9 inches (139612 steps, 111.3719 miles which is 60044.1072ft.)
How many calories per stride? 0.27049 calories (Kcal) per step (37763 calories / 139612 steps)
Graph and data shown below:
In response to “Biomechanical Energy Harvesting: Generating Electricity During Walking with Minimal User Effort,” (J. M. Donelan, Q. Li, V. Naing, J. A. Hoffer, D. J. Weber, and A. D. Kuo, Science, vol. 319, no. 5864, pp. 807 -810, Feb. 2008.)
It’s impressive and rather smart that they follow the regenerative braking example, since as shown in the charts they gain energy while assisting the deceleration required to take the next step. I would like to see the results for a second model built with the refined more-efficient gearbox they make reference to in the article. While the examples they mention of power usage in article (powering cellphones, prosthetics, and third world electrical applications), I wonder how the efficiency of the system will change when they need to add some way of utilizing and storing the power. If they plan to interface with already available devices, they will need transformers, regulators, etc which all add additional weight, however negligible it may be. Also, the inefficiency of longterm power storage is well documented, so I wonder if this device would help to trickle charge batteries or if the idea is more to continuous power distribution.