[Moved] I want to create a very cheap sports bracelet

[easygo]

I want to create a prototype of a very basic sports tracking bracelet. With this bracelet, all I need to know is how many calories I've spent while moving (dancing, running, football, etc).

My initial hypothesis is I need the following elements:

accelerometer
small memory for stocking running stats
USB connector for transferring data
is a small battery necessary?
would I need a gyroscope?


This would all be integrated into a silicon bracelet.

What would be the cheapest way to prototype this thing?
How much do you think it would cost me?
Maybe I am too optimistic and it's actually much harder than this?
In terms of design, I was thinking of somehing as simple as this:



but adding the additional elements.

 

[barry]

You would, at the very least, need a three-axis accelerometer, a small microprocessor, of course a power source, and USB or some other link (wireless?).

If you swing your arm up, you'll get the same acceleration as if you jump up, and that's a pretty big difference in work performed. How will you deal with that?