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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
HughB
We know extraction of steps from acc is difficult and best way to improve is test against a set of known results - as you did with stepcount.c
We also know that ground truth data is needed for that but difficult to come by (counting steps is cumbersome and other devices might not be reliable).
So what about the following idea (new or already discussed?): strap another bangle1/2 or puck at ankle.
That gives us
a) a file from wich step count should be extractable much more reliable since foot has much stronger and clearer pattern and much less distractions (other movements done with arm)
There could be a special ankle algorithm, but using the same one should work also I think especially if bangle2 for both would be used.
b) real ground truth, in that we know both recordings do have exactly the same step count (even if we do not know the count, we do have an error measure to minimize from the difference)
So far I have recorded two such pairs. Both times bangle2 (b2) at wrist and bangle1 (b1) over ankle. Additionaly I had a Mi3 band for comparison.
I have not done much analysis yet due to time limitations, but thought I post it here anyway in case anybody is interested to follow the idea or look into the files.