Collision avoidance

How can I detect a tree, human or vertical post from 10ft away?

hmm...

Some people at MIT used a kinect camera to 'see' what is in front of it. You could try that if you wanted, but you may be like me and not be able to write code that well... :~

The laser and camera thing would be a good idea, or if you used an LDR, mounted on top of the laser, you could detect the varying light intensity as it bounces of the object. You would probably have to put a 'tunnel' around the LDR, so external light doesn't affect it. The only reason I am not saying camera is that, correct me if I am wrong, the arduino cannot process images at a fast rate. That combined with the rest of the code could lead to a very slow program.

The arduino can process a serial JPG image. Or a Raspberry Pi can much faster. Can you think of a better way instead of a laser to avoid a collision?

I would suggest using a raspberry pi to process the images because I think that the laser and camera will be rotating around 360 degrees. This means that there will be a lot of images to process in one revolution. Unless you plan to have to camera and laser fixed forward, so the quadcopter knows what's in front of it...

You have seen this approach?

http://www.youtube.com/embed/TIpqxsVDgVs?rel=0&wmode=opaque

I'd be wary of relying on ultrasound in the presence of large volumes of whooshy air and spinny things.

No, only 90 degrees, 1 image. I have found a laser dot before years ago for a different project, in an image.

Great solution! Unfortunately we have already designed the hardware.

Unless you are worried about something hunting you, you only need to be aware of potential obsticles in the path of your present vector. Ignoring climb and dive, for the moment. that leaves fore, aft, right, and left. If you had a emmiter/detector of some sort (say ultra-sonic, shouldn't have a problem, if you stay away from the props) mounted on a gimbal under the bird, and with a 360 degree horizontal rotation. Tie the gimbal vector into your heading change and that should warn you of anything in your potential path (no idea how to guarantee adequare response times). Vector the gimbal down for descent, that takes care of dive. Vector up front for ascent and, if the props don't cause a problem, that handles climb. I really like the bump and go cage idea. I could 'a used that lots of times........ Hardware is already designed?? change the design.....