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Re: [SeattleRobotics] Re: nbot wall following

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  • Paul J. Ste. Marie
    ... I think that might have been similar one of my first attempts that did work well. The Maxbotix sensors I m using have a fairly narrow beam, and the problem
    Message 1 of 8 , Jun 20, 2012
      On 6/19/2012 11:25 AM, dpa_io wrote:

      > close range: turn SLIGHTLY away from the wall middle range: do
      > nothing (dead zone) far range: turn SLIGHTLY toward the wall out of
      > range: turn AGGRESSIVELY towards the wall

      I think that might have been similar one of my first attempts that did
      work well. The Maxbotix sensors I'm using have a fairly narrow beam, and
      the problem I ran into is that turning either towards or away from the
      wall causes the apparent distance to increase (1/cos theta). That
      didn't play well with straight proportional control (turn rate
      proportional to distance error), and PID was just a mess.

      Somehow the math needs to look at the rate of approach/retreat and the
      current turn rate and feed that into the PID. The other thing may be to
      use the derivative of the PID output as the turn rate.

      Other things I've considered are using two side sensors or putting the
      sensor on a servo and scanning left/right to locate the closest direction.

      -- Paul
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