This is not real automatic landing system so much as
it is an automatic flaring system.
Sharp makes a GP2DO2 solid state distance measuring sensor
that
can be
interfaced to the PICAXE It measures distances from 4
inches to 32
inches
with high rez. It uses the same principle the British Dam
Busters
use in WW II to destroy German dams. It measure the angle the
sensor
sees looking at a spot of infra red light reflected off the
runway surface.
You set up a decent rate of a couple hundred feet per minute
and let the auto flare unit take over at 32 inches. You
might also
want to monitor the air speed so it does not flare after
stall :)
The rest is software.
If you have a PIXAXE auto pilot altitude hold
you already have most of what you need. The idea here is mount
the sensor on the main landing gear axle and measure the
distance
100 times a second and control the elevator to flare
the airplane. If anyone is interested in this let me know
and I will upload info from a book I have on interfacing
PICs.
This could be handy for landing sea planes on glassy surfaces
or land planes at night.
Paul Lamar ...No rotor no motor.
Paul,
Your spies must have been hanging around my hangar. I have
actually
done what you're suggesting, but used the R144-GP2Y0A02YK sensor,
available from Acroname. Its range is 8" - 60", which provides 50%
greater range. Unfortunately, I haven't flown yet so I can't
say how
well it works. I have monocular vision, so judging distances
(close
up)
is a bit of a challenge. I ran across these sensors and
decided to buy
one and see what I could do with it. While it doesn't have a
perfectly
linear output, I felt it was good enough to provide a signal for
landing
purposes. (I never considered using a PICAXE controller.) I
hooked the
R144-GP2Y0A02YK sensor up to a 0-5v digital A/F gauge, the one
with
colored led's. I tried it out by hanging it out of the window
of my
truck while traveling down the highway at 65mph. I was
concerned that
speeds of 70-80 mph might degrade the signal. It seemed to do
the job
quite well. So, I built it into my left gear leg fairing and
mounted
the A/F gauge in my panel.
I'll let the group know how well it works in a month or two.
Mark S.
Lancair ES, N/A 20B
------------------------------------------------------
Great minds work alike :)
--
Paul Lamar ...No rotor no motor.
Using the truck to test the sensor is slick. In fact, do like Rutan
and
one could build a flying model and attach it to the truck on an arm.
Manually fly it off the ground several feet and then engage the autoland
system. Better to wreck a model than risk the real airplane.
BTW non-stereo vision is fairly common - even among pilots. Just be
sure to look as far down the runway as possible - improves the ability
to see change in distance above the ground based on angle.. Even normal
vision pilots do this...
Matt-
An RC model would work without the truck.
Fix it so the elevator servo is switched to the PIXAXE
control when it comes time to flare.
Paul Lamar ...No rotor no motor.
My initial idea was also an RC model, but I decided that might
unnecessarily constrain the prototype to being light weight and having
to interface the electronics/packaging with the servo. If I were doing
it, I'd start with a ground based vehicle and then transition to
something flyable, and then to a real airplane. Each step sounds like
it might be fun.
Regards,
Matt-
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.