Re: [Paparazzi-devel] RE: distance measurement for landing.

[Gareth Roberts]

Hmm, it's a British thing, we all learn about it as children.  
The Dam Busters was a project to destroy 3 German dams during world war
2.  They did this using round bombs that looked like barrels, which were
spun so they skipped like stones to get over the anti-torpedo
nets...quite incredible, but they discovered they needed to be a certain
height above the water for it to work, so they had two spotlights (nose
and nail) angled inward so that at the right height the two beams would
converge, so the pilots knew exactly what height to fly at (18 metres in
a heavy bomber in the dark over water...).
http://en.wikipedia.org/wiki/Operation_Chastise

As for the Gumstix, I'm working on a project at the moment using a
BeagleBoard (similar idea, bit more powerful I think) and a couple of
webcams to do some stereo ranging/optical flow work on a helicopter.
I'm sure it's possible to lift all the stuff, if you are lifting a
powerful linux sbc we may as well run the whole stack on it, which I
think is an excellent idea anyway (especially with the availability of
RT arm linux kernels).  Make the tiny into a simple IO device instead.
It's just that its quite a complex layer of hardware to implement what
should be a fairly simple sensor.

There must be something out there people :).
I saw a fantastic paper at EMAV by a guy using optical mouse sensors for
altitude control and object avoidance.  From what I remember, the return
from the sensors depends both on how high you are and how fast you are
going.  Wonder how accurate that would be, because we already know how
fast we are going...

--G

On Fri, 2009-11-13 at 09:38 +0100, address@hidden wrote:
> On Thu, 12 Nov 2009 15:54:13 +0000, Gareth Roberts
> <address@hidden>
> wrote:
> > Catches with the laser?  You'd probably need to lift an SBC
> > (gumstix/beagleboard), although you might get away with a CMUCam.  Not
> 
> Well, we already have Paparazzi running on a Gumstix Verdex and it
> does have a header to directly interface CCD-chips including working
> V4L-drivers.
> 
> > sure of the range, especially in bright sunlight over non-reflective
> > surfaces, like grass.  The ham radio one looks more promising, but
> > difficult and heavy.  Incidentally, I looked at the laser range-finder
> > idea quite a while ago after I saw a documentary on the Dam Busters!
> 
> Never heard of them. Do you have any pointers to this documentary?
> 
> Marcus
> 
> 
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