This the second semester I've used computer based labs with motion detectors.
I haven't had any problems (except for a bad ULI box). When you say the detect
ors don't work, do you mean that they don't record any motion or that the graph
s look bad. I learned the hard way that the motion detectors are very sensitiv
e. Students standing and moving nearby can make a mess out of the graphs.
Remember, the motion detectors act very much like bats - the first thing that
the waves bounce off of is the first (and only) thing they see. It's important
to have them aligned well with the carts (or person) and have no extraneous
motion or objects nearby. HOpe this helps.