Thanks everyone for such rapid and thoughtful suggestions. For those
interested, we reinstalled the Fanthom driver and NXT firmware update, and
re wrote and recompiled the program from scratch. The robot was still
behaving erratically. This is not a traction issue based on observation as
well as replacement of our treads with new ones. Eliminating our parallel
move blocks and using motor blocks as suggested by Mike (below) seems to
have solved the problem.
Mike:
Thanks for the suggestion and test code. It seems to have solved our
"ghost". We will incorporate motor blocks into our erratic main programs at
our next meeting and see if it solves our intermittent problems as well.
Hope to run into you to thank you in person.
Sincerely,
Bob Henshaw
Team Dynamite
From: Michael Brown [mailto:[log in to unmask]]
Sent: Tuesday, October 23, 2012 9:20 PM
To: Bob and Ann Henshaw
Subject: Re: [VADCFLL-L] looking for help with erratic robot behavior
Instead of using move blocks in parralell programing use motor blocks and
uncheck wait for completion so that both blocks execute at the same time..
Slow down your turns for accurate turns. see attached.
--
Michael Brown
Coach Team 4773
Waffle Bacon Bots!
"What we learn is more important than what we win."
On Tue, Oct 23, 2012 at 9:11 PM, Bob and Ann Henshaw <[log in to unmask]>
wrote:
Here is a simple program where the robot moves, stops on a line, executes a
2 motor 90 degree spin, and moves forward. At the end, it suddenly lurches
to the right, despite the stop block.
Thanks for looking at it!
Bob
From: Glenn Roberts [mailto:[log in to unmask]]
Sent: Tuesday, October 23, 2012 7:54 PM
To: 'Bob and Ann Henshaw'; [log in to unmask]
Subject: RE: [VADCFLL-L] looking for help with erratic robot behavior
My gut says there's a subtle bug in your software. Not sure, is there any
way to share an NXT program with this email group so others can look at it?
From: First Lego League in Virginia and DC
[mailto:[log in to unmask]] On Behalf Of Bob and Ann Henshaw
Sent: Tuesday, October 23, 2012 7:16 PM
To: [log in to unmask]
Subject: [VADCFLL-L] looking for help with erratic robot behavior
I am a 5 year veteran home based coach with a 2nd year team of 10 year olds.
We are working with a Mindstorms NXT system that we purchased new last year,
with a fully recharged battery. We are experiencing several intermittent
erratic behaviors (listed below) that is driving our team crazy. Please let
us know if you have any debugging suggestions.
Observed behaviors:
1. After completing a planned series of instructions, with the last
instruction having 2 wheels turning equally (straight line), the robot
suddenly makes an additional turn (one motor, rotating robot about 30 -
40degrees). This occurs even after deleting the program, recompiling and
redownloading it, and even after adding an all motor stop block to the
program. Our team is referring to this as a ghost and are convinced that the
robot is now haunted, just to get us in the Halloween mood.
2. The robot, using a two wheeled turn (one motor going forward, one
going backward) intermittently turns too far or too short. Programming is
being done in rotations for both motors. Because both motors are running
together, I can't tell if it is related to the problem above. This occurs
about 1 in 5 runs.
I do not think that this is a cable issue, as we are not seeing anything
beyond the usual minor navigation errors due to lineup, wrinkles in the mat,
etc. That leaves the motors and the NXT itself. Could this be a bad servo
motor and if so, is there any way to test them?
Appreciate your suggestions!
Sincerely,
Bob Henshaw
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