Subject:
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RCX Motor Diagnostic Test
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 2 May 2007 01:23:37 GMT
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Viewed:
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4363 times
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Hello. I’ve been thinking for a while about the best way to test a large
quantity of motors in a short period of time. The reason behind this is I mentor
an FLL team, and we recently acquired somewhere in the vicinity of 50-100 motors
from a now-defunct middle school’s classroom MINDSTORMS set. Because we have so
many motors now, I’d like to run a diagnostic on each of them to set up a motor
matching spreadsheet for the kids.
The test currently runs the motor at the five ROBOLAB power levels in each
direction three to five times, recording the number of counts from a rotation
sensor for each test. The current setup is a motor connected to a small (12t)
double conic bevel gear which meshes into a large (36t?) double conic bevel gear
with a cross peg with friction as its turning axle. This gear in turn meshes
with another 12t double conic bevel gear connected to the rotation sensor. Thus,
the motor is tested with a little load to produce actual speed variations. (PWM
will eventually produce the same top speed for any power level/duty cycle if the
motor has no load, due to the rotor acting as a flywheel)
The problem I am having is that I would like this to record the data into the
computer somehow, so I can transfer it to Excel. ROBOLAB is supposed to do that,
but I am having trouble getting it to do it easily.
In summary, I would like ideas on these two basic things: ÂÂ
1. Using the rotation sensor to measure axle speed. ÂÂ
2. Collecting and transmitting data from RCX to computer, preferably with
ROBOLAB but I can work with other languages.
If anyone has ideas on the following more advanced things, I would appreciate
them greatly: ÂÂ
3. Using the rotation sensor/other sensor to measure torque
for each data point. (this may require the redesign of test apparatus) ÂÂ
4.
Using the RCX to calculate averages before exporting data to the computer. ÂÂ
5. Having the data directly entered into an Excel spreadsheet. ÂÂ
6. Using the
new power level block (-100 to 100) and data from the sensor to draw a speed vs.
power level and/or torque vs. power level curve.
Thank you in advance for any suggestions, ÂÂ
Andrew Meyer
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Message has 2 Replies:
 | | Re: RCX Motor Diagnostic Test
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| Just a few general remarks on your setup/questions. There's a nice setup shown on Philo's page from when he compared the different LEGO motors, including some data sheets - maybe this is the type of data sheet you'd like to get? link: (URL) using a (...) (17 years ago, 2-May-07, to lugnet.robotics)
| | | Re: RCX Motor Diagnostic Test
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| (...) So ultimately you want as many matched pairs of motors as possible? I'm not at all sure why you need Robolab for this. 1) Set up all motors with identical loads (identical weights on strings hanging from pulleys, for example). 2) Power all (...) (17 years ago, 2-May-07, to lugnet.robotics)
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