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RC plane auto pilot — Parallax Forums

RC plane auto pilot

TKR182TKR182 Posts: 9
edited 2011-09-23 04:33 in Accessories
We are doing a school project in our engineering design and development class. Our idea is to build a auto pilot feature for a rc plane using an accelerometer and a PLC. We were wondering what equipment we would need, such as radio trancievers and recievers.

Comments

  • SRLMSRLM Posts: 5,045
    edited 2011-09-20 10:38
    http://diydrones.com/

    At a very minimum, you'll need either an IMU or 4 IR thermometers to make an autopilot that can even keep a plane level.
  • W9GFOW9GFO Posts: 4,010
    edited 2011-09-20 11:29
    Not necessarily. There are many airplanes available that are dynamically stable. That is, that they are self leveling. In particular the two channel RC gliders. The Gentle Lady is a decades old example, I built one in the mid '80s.
  • sylvie369sylvie369 Posts: 1,622
    edited 2011-09-20 13:52
    W9GFO wrote: »
    Not necessarily. There are many airplanes available that are dynamically stable. That is, that they are self leveling. In particular the two channel RC gliders. The Gentle Lady is a decades old example, I built one in the mid '80s.

    I recently built a similar plane, a SIG Riser, from a bag of balsa sticks, and after careful balancing, it flew beautifully hands-off on the very first flight. If the group working on this project is new to RC, I'd strongly suggest starting with a plane that has that characteristic. You'll save a lot of pain and expense.
  • alex123alex123 Posts: 102
    edited 2011-09-21 08:19
    An accelerometer may not be enough to keep the RC plane level. You'd need a gyro. The big disadvantage of an accelerometer is its sensitivity to... acceleration. It will gave you a good reading of a rotation angle only if the position is changing very slowly (~0 acceleration). Sudden or jerky changes (due to wind) of your plane orientation will cause an invalid data sent from your accelerometer.
    Gyros don't have this problem but gyros have a position drift issue therefore you need an accelerometer to correct for that.

    There is this neat gyro + accelerometer + compass board that I just bought for my home project:

    http://www.pololu.com/catalog/product/1264
  • alex123alex123 Posts: 102
    edited 2011-09-21 08:45
    I agree with sylvie369. Buy some light plane that can be fixed easily. The chances are during the initial testing you'll crash quite often.

    Also, to tweak your PID loop parameters you may need a better communication with your on-board PLD controller than just a PWM radio. You may want to think up front about some additional RF link to it. Zigbee or WiFi...

    On the other hand you may want to think of building a wind tunnel. This way the loop parameters can be tweaked through a wire. Several years ago I've seen a really simple wind tunnel design that used CPU fans. It was just a matrix of 25 fans powered from a benchtop power supply. Changing the power supply voltage will give you different plane speeds. Just a thought.
    Good luck!
  • TKR182TKR182 Posts: 9
    edited 2011-09-21 10:01
    We do actually have a wind tunnel at school and we were going to use it for our testing. And thank you for the suggestions, you probably just saved us a lot of time!
  • Tom CTom C Posts: 461
    edited 2011-09-23 04:33
    TKR182 wrote: »
    We are doing a school project in our engineering design and development class. Our idea is to build a auto pilot feature for a rc plane using an accelerometer and a PLC. We were wondering what equipment we would need, such as radio trancievers and recievers.
    TKR182,
    Here is everything that you have ever wanted to know about autopilots: http://www.diydrones.com/
    Hope this helps.
    Regards,
    TCIII
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