A.T.V. Autonomous Thermalling Vehicle

"Cruise control" for an e-glider.

I am building an e-glider that is controlled normally until you release the sticks. Then the autopilot kicks in and keeps the model around and starts looking for thermals or starts the motor when the glider is too low. No waypoints, its all about finding thermals.

 

Here is a video of my first long autonomous flight.
 

Untitled from Glider UAV on Vimeo.

 

Why an ATV?
- Wider search area
- More control (confidence) when further out
- Longer flight times, more searching
- Less effort / concentration
- More time to look around to find thermals (e.g. birds)
- Safety (failure transmitter / receiver)
- More efficient turning
- More efficient use of motor
- More options for trimming, mixing, speed, engine power
- Documenting flights, instructive

The unit can navigate in an circular area of 400 m in diameter. The model remains between 100 and 300 m altitude, using the engine if needed. The pilot can fly model until one releases the controls. In case of problems, including failure of the transmitter, the unit automatically land in the middle of the area.
An on-board camera allows video from the cockpit to be viewed after the flight. On the ground, I have a receiver that displays information about altitude, climb rate, airspeed etc. The data is also stored for later processing.

My goal is to develop techniques to have an e-glider autonomous fly as long and efficiently as possible. It is a challenge to make the electronics as small and simple as possible. My first goal was to have 100 m gain in a single autonomous flight using thermals, and I did.

I named my project ATV, which stands for Autonomous Thermalling Vehicle (and because I think the ESA variant is a wonderful piece of technology).

Height
The unit starts with the electric motor. It then climbs to 200m, then the engine is switched off while full throttle is still given on the transmitter. When the unit has dropped to 100m, this suppression of the engine will be lifted, and the engine will start again.

Navigation
Through four parameters, a semi circular area is defined within which the unit should remain. Once the aircraft is outside this area turns will be used to automatically bring it back in the area. It will only be flown within visual range.

Thermals
When the unit reaches 200 m, the motor will turn off and it will search for thermals. Only if there is good reception of the RC controller and GPS receiver is good and the height is between 100 and 300, there a right turn will be started as soon as rising air is detected.

Currently I fly with a Reichard Champion and a Topmodel CZ Fantasy . These models are just big enough for all the electronics to fit, and have decent performance. The heart of the autopilot is a micro-controller of Microchip, the PIC18F2550.
For the GPS receiver I have a GPS SkyTraq with updates every 1 second.
To measure the altitude and airspeed I use the VAT / VAM 300 with VAT GS by ELV.
I use an FMA CoPilot for stabilization.
I have two XBEEPRO modules for telemetry, which also supports a beep vario on the ground.

GliderUAV

Tags: atv, glider, thermalling, uav

Views: 2157

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Replies to This Discussion


3D RoboticsPermalink Reply by Chris Anderson on April 18, 2011 at 2:13pm
Sounds interesting. Got a link to a site with more info?
Permalink Reply by GliderUAV on April 20, 2011 at 3:56am

Chris,

I don't have a website but I added some more information. Just let me know if you want more.

 

GliderUAV

 

Permalink Reply by YureZzZ on April 22, 2011 at 4:54am
Hey I'm working on thermalling as well. We might learn some ideas from each other. PM me if you're interested.

DeveloperPermalink Reply by Mark Colwell on April 22, 2011 at 7:20am

Kudos for ATV,  You nailed it!

What type of cover material is used on piggy back pod? Is it IR clear?  Do you have holes for CP thermopile sensors? Very tight install looks great, Will you post auto pilot  and vario code ?  I would like to add a thermal seeker mode to ArduPilotMega. 

Permalink Reply by GliderUAV on April 22, 2011 at 9:29am

Thanks Mark,

 

Glad you like it.

The covermaterial is transparant shrink wrap for DIY battery packs. And you're right, i had to make holes in it, but i coverthose with magnetron foil, which is thin enough.

I haven't posted my code yet, but i might. It's in Jal v2,0 so its won't be very portable.

 

This is the method I currently use. It is known in the Netherlands glider-community as the "270 degrees method":
         -- devide the circle in eight sectors
         -- start thermal turn if not started and climbrate is above threshold but decreasing
         -- measure and store climbrate per sector passed (270 degrees)
         -- determine the best climb sector
         -- exit thermal 2 sectors before best climb sector
         -- fly straight on for 3 sec.
         -- this causes leveling off and flying to the better part of the thermal
         -- there a new cycle will start if rising air is found again
         -- all actions are monitored with a timer, so they cannot run for too long
         -- when only 1 sector has positive climbrate, the plane will head there
         -- when all sectors are below ThermalThreshold10 climbrate, turning stops

Good luck with your Megaproject, it would be great to have APM with thermalling.

 

Greetz,

GliderUAV


DeveloperPermalink Reply by Mark Colwell on April 22, 2011 at 9:38am

Thanks for your 270° method algorithm, This may be a bit more than I can handle but, time will tell.  

What is magnetron foil?

Permalink Reply by GliderUAV on April 23, 2011 at 12:03am
That's a plastic film used in microwave-ovens.

DeveloperPermalink Reply by Doug Weibel on April 22, 2011 at 9:02am
Nice project!

ModeratorPermalink Reply by Gary Mortimer on April 22, 2011 at 11:00am
Yep I think this was the one we all watched closely http://soaring.goosetechnologies.com/ I have been watching full size soaring today and was thinking yet again how wonderful it would be to send something off and watch it float around whilst sat under a tree!
Permalink Reply by GliderUAV on April 23, 2011 at 2:42am

Gary,

I watched that too.

 

Here is my list of favorites;

- Nasa Autonomous Soaring Project UAV Cloud Swift (http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=471)
- Dan Edwards - Aloft (http://soaring.goosetechnologies.com/)
- Staffan Kjerrström (http://hem.passagen.se/skj/engelska/NEWS2005.HTM)
- Andrea Salvatore http://diydrones.com/profiles/blogs/705844:BlogPost:31255

Great stuff. Thanks for inspiring me.

 

GliderUAV

Permalink Reply by by.charly on April 22, 2011 at 12:09pm

Very interesting project!

Estaré pendiente de tus futuras publicaciones.

Permalink Reply by Ritchie on April 22, 2011 at 2:35pm
Very interesting. Nice little project and clear concise goals. Please bring your thought to light here as I'm sure many will want to help you in this endeavour. Also a pic of your airframe would inspire imaginations :)

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