I'm trying to see if it's possible to measure wind speed.I would like to measure the wind's speed because I want to try autonomous landing.Do you know of any on-board system that could measure it?I think that I could use some anemometers in ground and send it to the UAV, but it's complex, and not very useful...
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i don't know what you have already set up in your plane...
but I think (newbie) that if you could get the speed of your aircraft with respect to the wind
and also get the speed of your aircraft using GPS, then (aircraft_speed - gps_speed) should
be approximately the wind_speed...
If you know your ground speed and true heading i.e. (GPS) and your air speed and the orientation of the aircraft with respect to true north i.e. (compass minus your local magnetic declination). The difference of these two vectors is the wind speed and direction. This is not so complex, the only, possibly, new sensors are airspeed and compass and some computing power. None of this is to hard to do.
Our UAV's that we use in the Army don't even have Auto Land with the exception of the Raven, and that is even a controlled crash. Raven Pilots go through a week of training and most of it is emphasized on using the sensors. Most Raven Pilots don't get to fly too often, so when they do, they rely heavily on the Auto Pilot to do it, and Landing is pretty Push-Button. The Bigger UAV's whose Pilots have a dedicated MOS, or Job Title of UAV Pilot, Land their birds Manually. I've shown our UAV operators how to land the Raven manually, and have taught them to bring them in a lot smoother than the Auto Land Feature does. Just my 2 cents
If you hold a constant pitch and a constant RPM, aren't you assured that your airplane will always settle into a constant airspeed and sink rate, regardless of wind?
I have developed my own glide/navigation software for gliders, determining wind speed is (obviously) a critical function. I know of several ways:
1. With GPS only, wind direction and speed can be determined by flying one or more circles at constant airspeed, then looking at how the GPS reported ground speed changes during the circle. When you are flying directly upwind, ground speed is lowest, when you are flying directly downwind the ground speed is highest. With a little more math you can get a decent approximation.
2. Again, with GPS only, fly two or more circles with constant bank and airspeed, calculating the center of each circle as you go. The center of the circle will (more or less) drift at the wind speed and direction.
3. If you have GPS, calibrated airspeed, pressure altitude, and outside air temperature, convert airspeed to true airspeed, then look at the difference between airspeed and GPS ground speed on three or more distinct headings. Add trigonometry and stir.
4. Finally, if you have GPS, calibrated airspeed, pressure altitude, outside air temperature, and a calibrated electronic compass, you have achieved nirvana, you can calculate wind speed and direction while flying in a straight line. The main issue is that it is very difficult to get sufficient accuracy and resolution out of the compass to get more than a rough approximation.
Most glider pilots fly with software (either firmware embedded in a flight computer, or on a PDA) that uses variations of 1, 2, or 3. 4 is a bit less common. The results of any method are usually "good enough" for our purposes.
Be aware that local wind speed and direction can change drastically as you descend below 200 feet above ground level, due to obstructions, trees, friction with the ground, etc.
thanks for the replies!
I was thinking on some way of knowing how the wind is moving in the landing area.
I know there's a way (desired direction - Real direction (GPS) ), but I would like to know if there's something more reliable...
Hi Paco
For auto land ??? If you want to control the speed of the model you nead ( air speed ).
Air speed is very inportant for your plane AIR SPEED is the deference betwen Dynamic and static air pressure.
You nead pitot tube and sensor MPX5050 and then you have to calbrate your airspeed ......
Is in my future plans to start airspeed sensor ....At the moment am checking witch sensors are arround the market .
I htink for auto land you ( airspeed , Altitude , )
Good luck
Stefanos (sory if my english are not good ! ! )
Replies
but I think (newbie) that if you could get the speed of your aircraft with respect to the wind
and also get the speed of your aircraft using GPS, then (aircraft_speed - gps_speed) should
be approximately the wind_speed...
-aludra
1. With GPS only, wind direction and speed can be determined by flying one or more circles at constant airspeed, then looking at how the GPS reported ground speed changes during the circle. When you are flying directly upwind, ground speed is lowest, when you are flying directly downwind the ground speed is highest. With a little more math you can get a decent approximation.
2. Again, with GPS only, fly two or more circles with constant bank and airspeed, calculating the center of each circle as you go. The center of the circle will (more or less) drift at the wind speed and direction.
3. If you have GPS, calibrated airspeed, pressure altitude, and outside air temperature, convert airspeed to true airspeed, then look at the difference between airspeed and GPS ground speed on three or more distinct headings. Add trigonometry and stir.
4. Finally, if you have GPS, calibrated airspeed, pressure altitude, outside air temperature, and a calibrated electronic compass, you have achieved nirvana, you can calculate wind speed and direction while flying in a straight line. The main issue is that it is very difficult to get sufficient accuracy and resolution out of the compass to get more than a rough approximation.
Most glider pilots fly with software (either firmware embedded in a flight computer, or on a PDA) that uses variations of 1, 2, or 3. 4 is a bit less common. The results of any method are usually "good enough" for our purposes.
Be aware that local wind speed and direction can change drastically as you descend below 200 feet above ground level, due to obstructions, trees, friction with the ground, etc.
I was thinking on some way of knowing how the wind is moving in the landing area.
I know there's a way (desired direction - Real direction (GPS) ), but I would like to know if there's something more reliable...
Do you have a preference for an autoland sensor? I know micropilot makes a sensor as others
For auto land ??? If you want to control the speed of the model you nead ( air speed ).
Air speed is very inportant for your plane AIR SPEED is the deference betwen Dynamic and static air pressure.
You nead pitot tube and sensor MPX5050 and then you have to calbrate your airspeed ......
Is in my future plans to start airspeed sensor ....At the moment am checking witch sensors are arround the market .
I htink for auto land you ( airspeed , Altitude , )
Good luck
Stefanos (sory if my english are not good ! ! )