To start, I want to thank you all for such a great site! I came here about a year ago and never quite got over how fun it would be to build my own UAV, so I'm finally going to try it.

Ideally the UAV would be able to receive some simple commands (fly to this location, raise altitude to this much, etc) and eventually carry a camera (something like this after being modified a bit, which will take pictures at the specified coordinates. Ideally the plane would just be stable, slow, and easy to control.

My current plan is to use the Easy Star body (most likely I will be suffering from some crashes, so foam is very good) with most of the suggested mods for it (faster motor, slower prop, etc). I'm currently planning on using the Arduino Duemilanove for the main controller on the plane (mainly for it's low cost and ability to output a lot of PWM signals easily and get inputs from lots of digital and analog sources). I'm planning on doing the coding myself, just because that should make it far more interesting. For sensors, I am going to try to use Sparkfun's pressure sensor and maybe their small 5 DoF gyroscopic and accelerometer board, along with a GPS (I haven't decided on the model yet).

One thing I'm not too sure about is what I will do for controlling it by radio. I am thinking about using these radio modules for their relatively low price and high power output, and then have some sort of setting on the plane to switch from auto-pilot to controlled directly from the radio. It seems to me that a lot of you have a failsafe backup computer as well as the radio control, to make sure that nothing can go horribly wrong, but I'm not sure how necessary this is, and I don't plan on flying the plane too far from where it takes off. I also don't know if something like those radios would be suitable for controlling the plane in real time. I would have a base station set up with a computer to control it and send it signals, as well as monitor the batteries and all that. I am also thinking about having some sort of failsafe system, where the plane will deploy a parachute if it is losing altitude too fast, the batteries somehow get lower than they should, or to help make it land without too much complicated control.

Some questions I have for you guys are: is there any reason I should use the IMU I listed instead of a thermopile? what should I look for in a GPS? do you think that radio would make sense for communicating with a UAV? does anyone know if a parachute system makes sense?

Any other thoughts or comments are greatly appreciated!

Views: 115

3D Robotics
Comment by Chris Anderson on November 7, 2008 at 10:45pm
Why do your own radio instead of just using off the shelf RC? It seems to add a lot of complexity for no obvious benefit. As for a GPS, an EM406 is easy to work with and there's lots of Arduino code available for it.
Comment by Tyler Nighswander on November 7, 2008 at 11:01pm
Choosing radio modules seemed to be cheaper (about $160 for the pair (although of course that doesn't factor in the other circuitry each would need to be fully functional)), more versatile (it's not really limited to finite channels, just bandwidth, and can easily send data back and forth between the plane and ground), and have longer range (each module goes up to 1W power which should be good for more than a mile at 915MHz). I guess I figured that since I wasn't really going to try using the plane as an RC plane, I didn't need to get bogged down with all of the extras that come with RC systems.

I don't really know too much about the radios on the standard RC systems though, so maybe I should look into that more. Do the lower end ones allow you to send/receive raw data to/from the plane?

3D Robotics
Comment by Chris Anderson on November 7, 2008 at 11:09pm
No, they're just one way. If you're a great programmer I can now (see my latest post) see that advantages of a DIY radio system, but all the other aspects of a autopilot are so challenging it just seemed like just one more thing to worry about and debug on an otherwise maxed out Arduino.
Comment by Tyler Nighswander on November 7, 2008 at 11:19pm
haha Funny how that timing worked out. I'll read up to see how they did their radio system. I was considering using the same module but I don't really trust it for long ranges.
I was hoping that maybe because the decoding of the radio messages should be pretty simple, it wouldn't tax the Arduino too much, but I guess it might be worth while using two controllers to minimize the load with the GPS, radio, and stabilizing if I try to do that myself.
Thanks for the helpful input!


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