Optical Mouse as Angular Position Sensor

There's a lot more noise in this system than in the original posters. He can control the features passing across the camera's field of view, and the direction is limited to two.

I think I'd bet on that one. In fact, if I ever get around to the hobby that never was, I might try using it for the encoder on that telescope I may never actually build.

CA

At agilent's site, navigate to: Home > Products & Services > Semiconductor Products Home > Motion Control Design Center > Product Selection Results: Reflective Optical SMT

If encoding a 1 dimensional surface is all that is required.

The optical mouse has a 16 x 16 pixel camera inside it. It takes images (maybe 1500 fps?) and does a 2-D correlation between one image and the next. From this calculation, the maximum in the x and y correlations gives the displacement of the mouse between the two image captures. The algorithm works well on random surfaces having sufficient contrast. On the other hand, one can envision surfaces with patterns where the correlation algorithm gets "confused." For example, consider a surface with an "egg carton" pattern. Depending on the pitch of the peaks and valleys of the egg carton as well as the mouse velocity and camera resolution, the correlation may indicate the mouse didn't move between image captures. Crank up Matlab and compute the autocorrelation of a sinusoidal function, and you'll see what I mean - no unique maximum. Its a manifestation of aliasing.

There is almost no chance this will happen when using the mouse on the average surface.