Creating a Coordinate System

rpierson

I am trying to use sensors (accelerometers and gyros), at
multiple locations, to create a coordinate system.  Our objective is to generate an alignment
system which could be used to align, and measure, two bones.  I am able to calculate displacement but am
having trouble processing the data into a coordinate system.  Do you know how I could do this?  Has it been done before?

Guarneri

Hi rpierson,

When tackling a problem like this, it's good to figure out what kind of data we can get from our sensors. In this case, accelerometer provides us an absolute position relative to gravity (provided the device is stationary) as well as relative directions when moving. Gyroscopes provide relative rotational speed data. 

This means that creating a coordinate system is going to be somewhat difficult, since most of the data is relative to each other. The one piece of "absolute" data you have to calibrate your system is your position relative to gravity when still. A good idea to try is calibrate your two bones as accurately as possible using your position relatively to gravity, then calculate their new coordinates using relative displacement data that you gather using your accelerometer and gyro.

Thanks,

Yu