I would also recommend looking closely at the wheels. Turn the robot upside
down as the drive wheels spin. Do they spin at the same speed? (Painters
tape is your friend). If not, one wheel is probably pushed too tight
against the motor. Do they seem to wobble? If so, a tire is probably not
properly attached to the wheel.
If you are using the caster ball that comes with the EV3 I would also
recommend that you take it out of the plastic mount and check both for
dirt.
On Oct 29, 2013 12:51 PM, "Mandy Wilson" <[log in to unmask]> wrote:

> There are a number of factors that cause this including but not limited to:
> ****
>
> ** **
>
> **1)      **Changes to the robot.  It’s amazing how one beam in a
> different place can change the way the robot works****
>
> **2)      **Line up issues.  Line the robot up 2 degrees to the left
> different at base and that translates to many degrees off several turns
> later****
>
> **3)      **Battery issues.  As the battery is fuller or less, power
> changes which can change how your robot reacts****
>
> **4)      **Friction.  If the wheels get a better grip on the mat one
> time versus another or are pushing something heavy which changes your
> friction, then that will change the way your robot reacts each time.****
>
> **5)      **Reset motors.   Sometimes the motors are still counting from
> a prior step and it messes up future steps.****
>
> ** **
>
> The Gyro sensor has improved our team’s consistency this year and is a
> HUGE improvement on the robot because it helps counteract some of these
> other factors.  However, due to line up and friction issues, the robot is
> still inconsistent.****
>
> ** **
>
> Good luck!****
>
> ** **
>
> Mandy Wilson****
>
> ** **
>
> *From:* First Lego League in Virginia and DC [mailto:
> [log in to unmask]] *On Behalf Of *Tonya Lapham
> *Sent:* Tuesday, October 29, 2013 12:34 PM
> *To:* [log in to unmask]
> *Subject:* [VADCFLL-L] Robot consistancy****
>
> ** **
>
> Hello,****
>
> ** **
>
> I seem to have this trouble each year.  The robot will be doing just fine.
>  Then suddenly the programs that were working fine now are not working the
> way they were programmed.  And it seem to happen about the same time during
> the tournament season, only it is with a different set of kids each time.
>  Any suggestions on how to trouble shoot these issues?
> ****
>
> ** **
>
> --
> Thank you!!****
>
> Tonya Lapham****
>
> Coach****
>
> Seismic Wave****
>
> ** **
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