Thread: RoboStars 'Mini-Arm' Control Device
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Unread 23-06-2002, 22:28
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#0047 (ChiefDelphi)
  
Join Date: May 2001
Location: Pontiac, MI
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Re: RoboStars 'Mini-Arm' Control Device
Posted by Chris.   [PICTURE: SAME | NEW | HELP]


Coach on team #308, Walled Lake Monster, from Walled Lake Schools and TRW Automotive Electronics.

Posted on 3/21/2000 6:02 AM MST


In Reply to: RoboStars 'Mini-Arm' Control Device posted by Steve Kalemkiewicz on 3/20/2000 6:03 PM MST:



: I was wondering if anyone had a picture of RoboStars' (#308) 'Mini-Arm' Control Device. I'm curious how the mini-arm stays in position after the controler lets go of it. Any other info that could be provided would be helpful.

: Thanks

: -S Kalemkiewicz

I don't have any pictures yet. There was a picture of us in the Detroit Free Press on Monday, March 13 and you can see the 'Mini-Arm' controller. I'll try to scan the picture and post it.

It stays in position by building some static friction into the system. We used some rubberized nuts so we could tighten the joints just enough so that the mini-arm would stay in place if you let go of it, but it is still easy to move.

The controller works using a simple proportional feeback control loop. We have potentiometers on the robot arm and on the mini-arm. When there is a difference between the potentiometers of the two arms, the controller multiplies this difference by a gain and this value is sent to the speed controllers on the arm motors. (Almost any engineer on your team could explain this in more detail if you asked.)

We used this type of control since we are using a double jointed arm. If we used joysticks it would be next to impossible to control (if we could control it, it would be sloppy at best). The mini-arm allows for extremely easy and accurate control. In fact, we rely on fast and accurate control since we only hold one ball. Our philosophy is that if we could do it fast enough, we don't need to hold multiple balls (we've done a good job so far - we scored 21 pts. one match by ourselves (and won) when our partner couldn't move their robot). Shown below is a picture of the robot. I will post the free press picture shortly.

If you're going to Chicago, feel free to stop by our pit and have a close look.

- Chris






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