Visual Odometry to Estimate Position without GPS??

Hi all,
Just wondering if anyone knows of alternatives to getting position information without GPS? I have an indoor helicopter which I have
autonomously hovering, but it starts to drift because of drafts or the IMU is not perfectly positioned (i.e. it's not exactly parallel to the ground). Double integrating accelerometer data is prone to error accumulation so that's not an option.
The only thing I can think of doing (excluding indoor GPS) is to point a camera down towards the ground and use some sort of visual odometry algorithm. If anyone else has any other ideas, I'd appreciate it.
If someone thinks visual odometry will work, I'd appreciate any advice on the fastest way to successful implementation.
Thanks in advance! -weg22
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<snip>
You might have a good idea there. Look at the optical mouse on any computer. It uses a small cell count CCD camera chip. They typically have something like an 18x18 cell array. That sounds wimpy but look at this project link:
http://www.contrib.andrew.cmu.edu/~ttrutna/16-264/Vision_Project/
I have a feeling that you could do something significant with this.
Cheers!
Sir Charles W. Shults III, K.B.B. Xenotech Research 321-206-1840
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Sir Charles W. Shults III wrote:

Or you can buy a miniaturized commercial version here: http://www.helicommand.com/home_en.html I was impressed that this idea went to market so quickly. It would be nice if we could modify these devices to do full-featured odometry (e.g. combine them with range sensors).
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message de ...

Thanks for this interesting link.. Fred
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snipped-for-privacy@drexel.edu wrote:

Directional ultrasonic rangefinders, with different frequencies?
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You might also find some interesting ideas, if nothing else, by Googling on "localization robotics". I stumbled upon "localization" on the Evolution Robotics website, and this group filled me in on what it meant. Sounds like the same sorta thing you need. Here's the Evolution link, just to get started: http://www.evolution.com/products/northstar/works.masn
Good luck ! JCDeen
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snipped-for-privacy@drexel.edu wrote:

If the indoor area you are flying in is rather small, you could place a planar visual target (with multiple easily detectable features) on the floor, and use something techniques like homography to obtain vehicle position and orientation. You might even be able to autonomously land a helicopter using this approach!.
Try the following papers for a good description. You don't have to implement the control approach presented in these papers if you don't need to. You can definitely do the visual position estimation part:
See PDF of my paper from: http://www.ces.clemson.edu/ece/crb/students/vilas/projects/landing/index.htm
A good paper on helicopter control using ground visual targets: O. Shakernia, Y. Ma, T. J. Koo, and S. Sastry, Landing an Unmanned Air Vehicle: Vision Based Motion Estimation and Nonlinear Control, Asian Journal of Control, Vol. 1, No. 3, pp. 128145, 1999
Vilas
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