Active Stabilization
This is a will ardupilot do that question. I've just built out my own telemetry system that uses GPS, GMRS radios and an arduino board. I've not built out ardupilot yet.
I plan to have a powered glider and I'd like it to be stabilized but not guided.
I'd like to do this based on flight time and I'd like to vary the desired angle of the nose relative to the horizon. while I'm on the subject... an Angle of attack gauge would be really cool for ardupilot.
Anyway... During the first few minutes of the flight while the glider is powered I'd like the nose held up xx degrees above the horizon. After this time period has passed I'd like to have ardupilot hold the nose at a lower angle that will be close to best glide. I think it's possible to mount two sets of sensors set to show level at the appropriate angle relative to the horizon but this seems clunky at best.
Hopefully my question makes sense and thanks!
I plan to have a powered glider and I'd like it to be stabilized but not guided.
I'd like to do this based on flight time and I'd like to vary the desired angle of the nose relative to the horizon. while I'm on the subject... an Angle of attack gauge would be really cool for ardupilot.
Anyway... During the first few minutes of the flight while the glider is powered I'd like the nose held up xx degrees above the horizon. After this time period has passed I'd like to have ardupilot hold the nose at a lower angle that will be close to best glide. I think it's possible to mount two sets of sensors set to show level at the appropriate angle relative to the horizon but this seems clunky at best.
Hopefully my question makes sense and thanks!
Replies to This Discussion
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Permalink Reply by Morli on -
It makes sense but you need to read the wiki for both Ardupilot and UAV dev board(UDB) a lot. You will be surprised to see where things have reached now. While you are at it , look at the software GCS too. Good luck.
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Permalink Reply by Donny on -
Yes... I probably just need to tinker with it. I was hoping to just get a quick yes Ardupilot can do that answer. I'm confident I can figure out how on my own.
This reminds me of trying to find community support for the gumstix computers.
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ModeratorPermalink Reply by Chris Anderson on -
Yes, ArduPilot (with ArduIMU) or ArduPilot Mega can do that. You'll have to tweak the code a bit, but it's not hard.
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Permalink Reply by Donny on
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Cool. Thanks. I think I'll just get the ardupilot board. I happen to have the two axis thermopile sensors Can you buy the Y sensor separately by chance somewhere?
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ModeratorPermalink Reply by Chris Anderson on -
I don't think you can reliably set a specific angle off level with the thermopiles. They're designed as levelers, not for accurate bank or pitch angle. (Depends on calibration, etc). That's why I recommended using it with ArduIMU, which does give exact angles.
But if you just want approximate angles, the thermopiles are okay. You can't buy the Z (which is what I think you meant) separately, but you can use just the XY if you go through a calibration process on the ground before flight.
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Permalink Reply by Donny on
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I did mean the Z sensor. My concer with the ArduIMU is that is uses gyros in place of thermopile sensors. My glider will be launched from a high altitude balloon. This means the glider will not be motionless when ardupilot is powered on. It's not clear to me if this is a problem but with traditional gyros I have used this would be a major problem as the gyro would never calibrate to level.
I also wonder if the pressure sensors would even be sensitive enough at extremely low air pressures.
That combined with the fact that I can't really have a UAV beyond line of sight left me thinking what was the simplest way to actively 'stabilize' (not guide) the glider for a short flight. Imprecise horizon angles would probably work fine so long as I could reliably get within a few degrees of a given angle relative to the horizon.
It does sound like I'll need that Z sensor if I use thermopiles to properly orient the XY sensor at altitude.
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ModeratorPermalink Reply by Chris Anderson on -
Good point. If you can't power on the IMU on the ground, you will indeed be better off with thermopiles (which were actually designed by NASA to work in space!). And yes, in your application you will need a Z. I'm afraid we only sell them in matched sets.
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Permalink Reply by Donny on
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Very helpful, Thanks. I'm planning to buy this glider for the flight and I suppose I'll tackle ardupilot in the coming weeks. I'm doing a flight test on the new arduino based telemetry system in the next week or two so I'll want to verify that works as expected prior to going on to the next phase.
The ArduIMU would be ideal as I could use it to run my custom telemetry system but won't work because of the gyros. In the end it's probably best to have independent systems for telemetry and stabilization anyway.
http://www.skykingrcproducts.com/rcplanes/slope_planes/brian_courti...
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Permalink Reply by bGatti on -
I suspect that you would find airspeed to be a sufficient indicator of "angle of attack".
if you target an ideal cruising speed, and pull up when faster or drop the nose when slower, you should be able to use the existing airspeed indicator to hold an attack angle. A two-sensor solution might react more quickly?
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Permalink Reply by Michael Zaffuto on -
An AoA sensor was previously discussed briefly and resulted in this link to Charles River's Albatross
This is his schematic: http://www.charlesriverrc.org/articles/asfwpp/lelke_alb1electronics...
This is his AoA Sensor: http://www.charlesriverrc.org/articles/asfwpp/lelke_launch.htm
Pressing "Back" and "Next" on his site will reveal additional info.
His AoA sensor is a low friction vane with magnets exciting a HoneyWell 91SS12 Hall Effect sensor
providing an analog output voltage to represent angle of attack.
It wouldn't be too much work to replace his PIC microcontroller with this sites autopilot hardware
(of which has a lot of goodies that would be useful).
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