I should also have said (between #1 and #2) that anything touching the mat on the "C" side would cause the behavior as well.

And, that I believe that a defective "C" motor is unlikely - only mentioned because it is possible.

What does your drive train look like (simple wheels, simple treads, or a complex mechanism) and what contact with the mat is there besides the drive mechanism. 

One year the team didn't do a good job of setting the height of attachments (or initial placement), so they dragged a lot, but with no constancy. As a result, they never knew which way the robot would go because the controller frequently couldn't compensate (and they had a pretty simple drive mechanism) - they ran into alot of stuff and subsequently didn't score well.

Brian

Sent from my iPhone

On Nov 1, 2013, at 9:37 AM, Rahman Rasulzada <[log in to unmask]> wrote:

> <Presentation1.jpg>
> Here is the what we are having problem
> 
> 
> On Fri, Nov 1, 2013 at 8:30 AM, Rahman Rasulzada <[log in to unmask]> wrote:
>> Hello folks , 
>> 
>> We are  having a trouble with new Ev3 large motors. Robot wheels not going straight however they put same values (rotation or degrees) but robot degree values change automatically... My students reset , and updated firmware but still having same issue. Motor values keep change ........
>>  
>> Any suggestion ? Really appreciated
>> 
>> 
>> -- 
>> _________________________
>> best regard,
>>  
>> Rahman Rasulzada 
>> Pinnacle Academy ,
>> IT Manager & Computer Teacher
>> School Website 
>> Personal Website
>> Computer Classroom Website
> 
> 
> 
> -- 
> _________________________
> best regard,
>  
> Rahman Rasulzada 
> Pinnacle Academy ,
> IT Manager & Computer Teacher
> School Website 
> Personal Website
> Computer Classroom Website
> 
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