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UAV Autonomous Unmanned Aerial Vehicles > Any one runing with laser altimeter?
 
 
ZOOM_BR
Heliman
Location: Goiania,GO - BRAZIL

My Posts This: Topic  Forum		Any one runing with laser altimeter on VTOL auto-landing?

I would like to hear your experiments.
02-21-2009 08:45 PM
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LoopZilla
Heliman
Location: Melbourne, FL

My Posts This: Topic  Forum		Laser altimeter

A laser altimeter works fine until the ground surface becomes reflective. Just picture a dirt field with a puddle of water in the landing zone. When the laser gets over the water, weird things happen.

That effect can be minimized in your computations, if you filter out excessive variations and constantly compare to other known, but less accurate, values (GPS or pressure HAG).

However, I have found that rate of decent is the best way to handle landing in most any environment, and it doesn't take more hardware. It does take a lot of programming and platform specific integration.

However, I do have laser rangefinders on board, but more for targeting purposes.

Later!

LoopZilla
02-27-2009 02:26 PM
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RChelisrock
Heliman
Location: Virginia

My Posts This: Topic  Forum		Laser range finders can be very effective for landing - but you have to get the "pricey" ones. You get what you pay for - if you use one that is a few hundred dollars then expect to get low performance under the kind of conditions encountered by a VTOL UAV.

I have used one that is made in Germany - it is very accurate whether point it at a tree, bushes, grass, pavement, etc.

Of course - as was stated above, it will not work with water. The technology is improving rapidly and I was very impressed with the performance of this system.
05-01-2009 01:02 PM
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DKNguyen
Senior Heliman
Location: Alberta, Canada

My Posts This: Topic  Forum		Maybe everyone's cost ceiling here is much higher than mine so I don't even consider laser altimeters...but don't they cost at least ten thousand dollars?
06-22-2009 09:05 PM
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just4fun2
Senior Heliman
Location: torrance

My Posts This: Topic  Forum		where do you find these laser alt.??

anyone try hacking automotive car back up sensor for sensing distance to landing or low level flight? the guys at eagletree are very helpfull with adding on sensors.
09-01-2009 04:08 AM
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LoopZilla
Heliman
Location: Melbourne, FL

My Posts This: Topic  Forum		Aerius Photonics (http://aeriusphotonics.com/prod_ultralight.html). Have used this one in the past, and it is a great unit.

Sonar systems will work for very flat and level terrain following, but you must be well within the 'death' zone to have them work.

Plus, imagine flying over tall grass or brush on your approach to a landing zone.

I have been struggling with this issue for some time, and I think I am going to go the route of image based rectification.

If anyone is familiar with 'Canesta' imaging, then the idea will become apparent (http://canesta.com/products-and-tec.../camera-modules). I have used this in the past with ground robots, and you can actually see in 3D (depth displayed as varying colors). However, the image resolution was very poor at the time, but may still work perfectly to know altitude, and more importantly, if you are landing on top of an object.

LoopZilla
09-01-2009 04:25 AM
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zozie
Senior Heliman
Location: Mississauga, Ontario, Canada

My Posts This: Topic  Forum		Anyone ever thought of using an ultrasonic range finder?
Just an idea. Works well for short range (6-10M) and refelctive surfaces are not an issue.

No honey I got that used.... MAAC#73745
09-01-2009 11:55 AM
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