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 Robotics / 27072
27071  |  27073
Subject: 
Re: RCX Motor Diagnostic Test
Newsgroups: 
lugnet.robotics
Date: 
Wed, 2 May 2007 08:00:19 GMT
Original-From: 
linmix <linmix@gmail.comNOMORESPAM>
Viewed: 
4582 times
  
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:
http://www.philohome.com/motors/motorcomp.htm

By using a similar setup and attaching different weights you may get a
more complete picture of torque differences between motors (if they exist).

The datalogging utility in RoboLab provides different types of graphs to
analyse the data gathered. Do you really need an Excel spread sheet?

Finally, visual inspection will tell you if all your motors are of the
same kind. The part number is printed on the bottom of each motor (71427
vesrion 1 and 2 or 43362). This will allow you do an initial sorting
since they are a little different - again see Philo's page for more details.

linmix

Andrew G. Meyer wrote:
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: ¬
1. Using the rotation sensor to measure axle speed. ¬
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: ¬ 3. Using the rotation sensor/other sensor to measure torque
for each data point. (this may require the redesign of test apparatus) ¬ 4.
Using the RCX to calculate averages before exporting data to the computer.
¬
5. Having the data directly entered into an Excel spreadsheet. ¬ 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, ¬
Andrew Meyer





Message is in Reply To:
  RCX Motor Diagnostic Test
 
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 (...) (18 years ago, 2-May-07, to lugnet.robotics, FTX)

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