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How does ArduIMU and IMU in general work?

Posted by scott on March 17, 2010 at 8:39am
Something has been somewhat confusing to me. No matter where I look, I cant find a straight explanation as to how autonomous aircraft stabilize themselves. I know the Ardupilot uses thermopile sensors. Do real drone aircraft use thermal horizon sensors? I know gyros are commonplace though. As for the IMU, I realize since its internal and gyro based, there has to be some drift. How is the drift reduced to the point where it can be used to fly an aircraft? It it used in conjunction with other sensors to get more points of reference then mix itself in with programming? Somewhat like being able to auto recalibrate in flight? Or is it kind of like a traditional model aircraft gyro, where it just stabilizes flight against unwanted movement. How much of an improvement in stability can an ArduIMU offer over just thermal sensors? I will not be using them anytime soon, I think they are not yet implemented fully as for the open code, but I am just curious. Are there any other sensors commonly used in UAV type aircraft in general?

I wish I could find a good overall guide or explanation for UAV stabilization.

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Replies

  • Developer
    Doug Weibel March 18, 2010 at 9:21am
    With the new firmware you use either ArduIMU or the thermopiles, not both. In terms of ease of use it may be a toss up. Both have their own issues. With the IMU you have to be concerned with vibration...
  • Developer
    Ryan Beall March 17, 2010 at 8:47am
    In short IMU's use complicated attitude estimation algorithms that are pretty math entensive. The general idea is to blend or complement two sensors together to get the best of both worlds. Gyro's drift and accelerometers are noisy but thy can both be used to determine attitude. The accelerometers keep the gyro drift stabalized.

    Then once you have a stable attitude solution, you use that to keep the wings level using a negative feedback loop of the error. IE: if you want to keep the wings level and they are not then move the ailerons to correct in the opposite direction
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