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

[gisela.noci]

Have tried this type of sensor - useless - does not work at all over grass,
nor over desert gravel/sand mix. Ok over tarmac runway, up to maybe 2meters
- not really a reliable option at all - really needs good surface
reflectivity

I do autoland using ultrasonic sensors - 4 Murata MA40B8S transducers pulsed
in parallel with 55volts Peak to Peak, and 1 MA40B8R as receiver sensor, in
an own designed circuit. This works very well, giving 8 meter reliable
detection over almost any bad terrain, except tall grass ( tall = more than
500mm). Over Tarmac range is about 13meters. Uses a PIC processor. 

You need LOTS of TX energy, hence 4 transducers hammered at the max voltage.
The LV-MAXSONAR EZ series are as useless - just not enough energy for
surfaces with low reflectivity. 

 I am working on a UWB radar ranger, which is really the answer - 2 watts
power consumption will give range from 200mm to 1200meters, the hassle is
antenna space needed - will not work on your average flying wing type A/C,
but great on a 60 size trainer or similar.

Don't waste your money on the Infra Red route...
Joe

-----Original Message-----
From: address@hidden
[mailto:address@hidden
] On Behalf Of Chris
Sent: Friday, November 06, 2009 7:42 PM
To: address@hidden
Subject: [Paparazzi-devel] distance measurement for landing.

Hi.
I would like to hear any opinions on those sensors:
http://www.acroname.com/robotics/parts/R302-GP2Y0A700K0F.html
and
http://www.acroname.com/robotics/parts/R144-GP2Y0A02YK.html
They look interesting and i am tempted to try and add them to the paparazzi.
Which one should you choose?
Chris



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