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servo jumps at start of match 
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Joined: Tue Jan 05, 2010 8:32 pm
Posts: 2
Post servo jumps at start of match
We have a ball holder attached to a servo. The idea is to lift the back of the ball holder to release extra balls at the end of the match. The good news is that it works great. The bad news is that the servo often jumps at the very start of the autonomous mode for no apparent reason.

We tried telling the servo to go to zero during the special "initialization" phase, but that didn't seem to help.

Does anyone know how to make the servo sit still?

We want the servo to stay at zero until a specific button is pushed.

Is there some kind of hardware or software solution?

thanks,
Mark


Wed Jan 06, 2010 9:55 am
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Expert

Joined: Mon Oct 27, 2008 9:59 pm
Posts: 137
Post Re: servo jumps at start of match
Honestly, it sounds like you most likely have a coding error. The servos are pretty good at going where they are told to go.
If you want to attach or post your code (using the code tags), I think we would be able to help more.


Wed Jan 06, 2010 10:44 am
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Joined: Tue Jan 05, 2010 8:32 pm
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Post Re: servo jumps at start of match
It turns out this was a hardware problem.

The "zero" position was not where the unit stayed when it was at rest.
The jump was the servo getting from its overextended rest location to the "zero" position.

The solution was to put a long screw through the bottom of the ball holder to press against another component and lift it up about 1/4 inch. Now the servo rest position is even with the "zero" position.


Wed Jan 06, 2010 11:12 pm
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Joined: Mon Oct 27, 2008 9:59 pm
Posts: 137
Post Re: servo jumps at start of match
You can position the horn on the servos in any orientation so that you get an ideal range of movement relative to the rest of the robot (including where "zero" is in terms of whatever you've connected to the servo.

Also, I don't believe the servo will jump to zero if you set it's target to the desired starting/rest position correctly in the beginning for your program.

I may be misreading your post, but if you're using a screw to physically block the servo from going where it is trying to go, you're likely to end up needing a new servo when you strip the gears in the one you're stressing. Hopefully you used the screw to just adjust the location/orientation of the servo (I believe that is what you did).


Thu Jan 07, 2010 1:57 pm
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