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Control Theory Question

  1. Apr 15, 2010 #1
    In most systems there is some sort of damping, but is it possible to develop a controller that works efficiently in a system with no damping? For example, imagine tracking the position of a linear cart moving on a track with no friction. Would it be possible to design a controller to supply a force to the cart at the start, turn off, and then apply a force when needed in the opposite direction to bring the car to a complete stop with little to zero overshoot? This somewhat resembles a critically damped controller, except for the middle part when no force is applied and the car is coasting without the effect of friction. If anyone knows any websites or books that would help it would be greatly appreciated, thanks!
  2. jcsd
  3. Apr 15, 2010 #2
    The problem here is that there is no such system that lacks damping. Also, why would you have a controller supply a force, turn off, and turn on again? That's not how controllers work. A controller is turned on, and it says on, providing feedback to stabilize the system. Also, your controller will be designed to add artificial damping because a zero damping system is on the verge of instability (i.e., bad).
  4. Apr 15, 2010 #3
    The scenario I was thinking of is satellite attitude control. I would think that a rotating satellite would continue to rotate if it were sufficiently high enough (perhaps GEO orbit) with negligible effects from solar wind and cosmic rays-at least on the time period that we would care about (hours or days)
  5. Apr 15, 2010 #4
    Good observation! But again, it appears to me that you would still want damping in the system for stability in the form of thrust augmentation.
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