Motor Analysis

The FLL team that I mentor has several hundred motors, both the new and the old
ones. This wealth of motors got me thinking "Well, out of that size a sample,
there's gotta be two that are perfectly matched, and some that are close. I
should analyze all of them..." So, I built a simple little test mount to run
them in. It has a rotation sensor connected to the motor by the double bevel
gears, using the friction cross-over pins to simulate a load. That...was the
easy part. The part that I thought would be easy (the code) isn't. What I tried
to do is run the motor at power levels 1-5 forward, while recording the sensor
data as data points. Then, I run the motor in reverse, power levels 1-5, while
datalogging the rotation sensor data. This process is repeated three times. What
I wanted all of that to do is calculate the loaded RPM of the motor at each
power level, as a useful and fair method of motor comparison. It doesn't. The
problems I think I ran into:
*integer math
*no absolute value function
*unfamiliarity with Robolab's Investigator section

Is what I'm trying to do a reasonable thing to want to do with an RCX and some
free time? Is it possible? Has anyone else ever done things like this before?

Any and all help will be much appreciated, and I can email code if you let me
know. Also can post pictures of rig if needed.

Andrew Meyer