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First Lego League in Virginia and DC

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Subject:
From:
Fredrik Nyman <[log in to unmask]>
Reply To:
Fredrik Nyman <[log in to unmask]>
Date:
Fri, 14 Nov 2014 10:50:18 -0500
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Lego motors are inherently imprecise, so it is perfectly normal for one
motor to run slightly faster than another.

You may find this article helpful:
http://www.techbrick.com/Lego/TechBrick/TechTips/NXTCalibration/

(NXT article, but just as valid for the EV3).


On Fri, Nov 14, 2014 at 10:40 AM, Neelam Kadam <[log in to unmask]> wrote:

> Our team's robot is well balanced for the most part but has a couple more
> pieces on the left side. It has two large motors driving the two wheels.
> When testing it to see how straight it goes, it was veering slightly to the
> right consistently. We just switched the ports to which the two motors are
> connected and now it is going straight. Can anyone explain what might be
> the reason?
>
> Thanks
> Neelam
>
>
>
> On Tue, Nov 11, 2014 at 7:55 AM, Neelam Kadam <[log in to unmask]> wrote:
>
>> Thanks! That is a great idea! We were thinking of doing it indirectly by
>> moving into the "zone" past the other lines using rotations and then start
>> the sensing but your way is much simpler.
>>
>> On Tue, Nov 11, 2014 at 7:52 AM, Anant Narayanan <
>> [log in to unmask]> wrote:
>>
>>> You can use the motor rotation sensor to restrict comparison analysis to
>>> "in zone"
>>>
>>> If B Motor Rotations are between x and y AND color is GREEN  or YELLOW,
>>> etc.
>>>
>>> Good luck.
>>>
>>> Anant Narayanan
>>>
>>>
>>>
>>> *---------------------------------------------------------- Anant S
>>> Narayanan Founder & Executive Director*
>>>
>>> *McLean Robotics Institute*
>>>
>>>
>>>
>>> * McLean VA 22102 202-421-3826 <202-421-3826> (cell)
>>> [log in to unmask] <[log in to unmask]>
>>> -----------------------------------------------------------*
>>>
>>> On Tue, Nov 11, 2014 at 7:49 AM, Neelam Kadam <[log in to unmask]> wrote:
>>>
>>>> That is what we do to get around the problem. But does not always work
>>>> because of other color lines in the way.
>>>>
>>>> On Tue, Nov 11, 2014 at 7:46 AM, Anant Narayanan <
>>>> [log in to unmask]> wrote:
>>>>
>>>>> One of our teams faced this problem at the competition, but didn't
>>>>> take an extra color sensor.  One of the kids remarked that a green mat line
>>>>> looked a tad yellow.  I think the mat colors were matched to the sensors,
>>>>> but  there may be production variations between mats ... one more issue to
>>>>> worry about, besides imperfect tables :-)
>>>>>
>>>>> Our senior team fixed a similar problem with red, which the color
>>>>> sensor was sometimes reading as brown (using the port view on the brick),
>>>>> by making the comparison test "red" or "brown" -- I hope you know that you
>>>>> can test for multiple colors by making multiple checkbox selections on the
>>>>> EV3 color sensor block.  This may be another option.  In Mindstorms NXT, we
>>>>> had "inside range" and "outside range" sliders.
>>>>>
>>>>> Best,
>>>>> Nari
>>>>>
>>>>>
>>>>>
>>>>> *---------------------------------------------------------- Anant S
>>>>> Narayanan Founder & Executive Director*
>>>>>
>>>>> *McLean Robotics Institute*
>>>>>
>>>>>
>>>>>
>>>>> * McLean VA 22102 202-421-3826 <202-421-3826> (cell)
>>>>> [log in to unmask] <[log in to unmask]>
>>>>> -----------------------------------------------------------*
>>>>>
>>>>> ---------- Forwarded message ----------
>>>>> From: Amy Nichols <[log in to unmask]>
>>>>> Date: Mon, Nov 10, 2014 at 6:30 PM
>>>>> Subject: Re: [VADCFLL-L] Thank you!
>>>>> To: [log in to unmask]
>>>>>
>>>>>
>>>>> Jill...
>>>>>
>>>>> That was exactly our the trouble we had.  The color sensor read the
>>>>> black, white, and red, but would not read the green.  The kids thought
>>>>> calibrating the sensor would help, but nothing they tried worked, until
>>>>> they replaced the sensor with another. As soon as they did that it worked
>>>>> fine.  I don't know if each sensor has it's own sensitivity or if the one
>>>>> they had been using all season was just worn out.  My son said he's going
>>>>> to take the replaced one and try it again at home, just to see what
>>>>> happens. It's interesting that your team also experienced the same thing!
>>>>>
>>>>> Amy
>>>>>
>>>>>
>>>>>   On Monday, November 10, 2014 6:24 PM, Jill Hamilton <
>>>>> [log in to unmask]> wrote:
>>>>>
>>>>>
>>>>>  Amy, thanks for sharing.  We found this too.  Our EV3 color sensor
>>>>> wouldn’t read green.  We realized it was too close to the table.  I am
>>>>> curious what you learned during the competition that helped.
>>>>>
>>>>> Thanks
>>>>> Jill Hamilton
>>>>> Coach of Cyborg Piñata 3335
>>>>> Coach of the Mechanical Manatees
>>>>> Coach of the Electric Pineapples
>>>>>
>>>>>  *From:* First Lego League in Virginia and DC [mailto:
>>>>> [log in to unmask]] *On Behalf Of *Amy Nichols
>>>>> *Sent:* Sunday, November 09, 2014 10:15 AM
>>>>> *To:* [log in to unmask]
>>>>> *Subject:* [VADCFLL-L] Thank you!
>>>>>
>>>>>  I want to offer a huge thank you from The Ruling Robot Falcons to
>>>>> Karen Berger and all the organizers, judges, referees, and volunteers that
>>>>> helped put on the regional tournament in Newport News yesterday.  Our kids
>>>>> had such a fun time and I appreciate all the work that was put into it!  I
>>>>> think the referees were cheering for all the kids as much as the coaches
>>>>> were!  Thank you all!
>>>>>
>>>>>  I also want to add a note about real Gracious Professionalism that
>>>>> happened for our team yesterday.  When we arrived at the school yesterday
>>>>> and our kids ran their robot on the practice boards, they discovered that
>>>>> nothing on their robot worked.  All their missions were dependent on the
>>>>> color sensor, which had was only randomly seeing certain colors.  They
>>>>> tried everything they could think of to fix it, but then got the idea to
>>>>> see if the other teams that had EV3's could help.  So they went around the
>>>>> room asking other teams if they had any ideas or knew how to calibrate a
>>>>> color sensor (one of the things they thought perhaps was wrong).   The
>>>>> other teams all stopped what they were doing to help our kids try to
>>>>> problem solve and help think of what could be wrong.  It was very apparent
>>>>> that these kids were not just there to win a tournament...but they really
>>>>> loved being there and wanted to help.  This just made me love FIRST/FLL
>>>>> even more than I already did, and realize just how great this organization
>>>>> is!
>>>>>
>>>>>  Thank you all!
>>>>>   ------------------------------
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