Wednesday, November 17, 2010

UGV Autopilot Revisited

We have been working on lots of projects lately, mostly about the UAVs again. Only two hands and all, the last parking lot test that we ran were successful in clear areas. If you just wanted a clear circuit, our simple guidance system was good about being repeatable around 20mph. However, we want to get more in the low end in this, so that we can handle cornering better. The avoidance model is where we are looking for some help.

We are trying to get a working optical flow system to work at these speeds. You can get a working system at low frame rates, but we will need to increase our computing capacity to get it to work successfully at these speeds. Our issue we think, is in the matrix inversions. The determinant terms are making too many things blow up by divisions of small numbers. 

We are looking for anyone with experience getting an effective Kalman filter to work on Android. We have a few older phones, bhat we think would be a good platform for doing 2d control. Yes, I am mixing discussions a bit. If we can better estimate the net acceleration, it would help debug our optical flow system. We are having to bracket our responses so that the AI does not jerk the wheel. This seems to be an  issue. If optical flow can be used to manage the jerk, I think that we can even have moving obstacles in the scene and still reacquire the path with no issue.

It seems to be that the vectors estimated with Kalman divides by zero and runs a huge acceleration and that ruins the math for several iterations. Then the ringing dies out and the system cam go on, by that time we are either running for the hills because a dog liked the truck or because something blew across the scene. I have to find the math error. 

Contour 1080p HD helmet cam

So far so good with the helmet cam. We have been playing with its high frequency stabilization technology. This is pretty effective at taking the jelly and jam out of the motor shakes. Which is a good sign, it is effective at taking out suspension bob when riding a bike, but low frequency motion it can only do so much with. If you move the camera 3" it can't take the shake out of that. You would not really expect it to.

At night, or in low-light conditions it gives a pretty good picture until it is hard to see. Once you break that threshold it is too dim as well. It does have a pretty good sensor, it can pick up even small changes in brightness well and does well with edges.

At the moment, I have yet to get virtual dub to open a quicktime movie. None of the plugins that have been found work. Although I am loathe to say it, it may be better to just go the Quicktime Pro route. Legendary fail of customer support is always a reason why Mr. Jobs' overpriced fanboi kit rarely graces my workspace. It may be a necessary evil this time. Especially, if it can automatically export all of the movie's frames in one drop.

I am not done testing the camera, but so far I recommend it. For the money, it is very usable, rugged and has a functional output that is good for tv viewing. Reliving past exploits are always a great way to kill  time while you lie to yourself about  how good you were.