This is a fork of ArduPlane made by Pete Brawell that supports thermal soaring.
we work on paper of peregrine falcon thermal soaring strategy in http://www.technologyreview.com/view/421901/peregrine-falcons-inspire-new-thermal-soaring-strategy-for-uavs/. with Pete's thermal mode decribe after ( many thanks to him , he's a great guy!), we cannibalized a flight mode (stabilize) , mod it, to implementet falcon's strategy. We also add Reichmann rule (partially) in which when you're in thermal you decrease roll angle to increase vertical lift, and when the last stops go away.
It's an alpha release to test very well.
This is a highly experimental version of ArduPlane based one ArduPlan v2.68. This version of ArduPlane as of now (January 21, 2013) has only been simulator tested in X-Plane. I'll update this document as more testing (eventually live) is complete
I have modified it to have a basic "soaring" or thermal mode. This is primarily intended for sailplane pilots who want an autonomous soaring. As of this initial Alpha release, the software has only been tested in X-Plane v10. The results are promising. I've been able to fly a several 30KM tasks with an electric sailplane model in varying soaring conditions ranging from strong thermals extending to 10,000 feet to a relatively modest day where thermals are sparse and top out at only 3000 feet. More testing however needs to be done.
I envision this software used in two modes, at least as I'm conceptualizing it at this point. One mode is soaring assist whereby a fly-by-wire mode (FBW-A in this case) is modified with a thermal hunting mode based on rate-of-climb. When the ROC exceeds a variable parameter, the aircraft goes into CIRCLE mode. This is simplistic. It can probably be enhanced, but it seems to work surprisingly well.
The other mode is full autonomous soaring from way point to way point. In this mode, I've modified the AUTO mode to contain the same thermal hunting algorithm explained above. In this mode, a flight is planned and uploaded via the APM flight planner and the flight is autonomously flown from way point to way point.
More information here: ArduPlane / DIYDrones website Specifically take a look at the ArduPlane manual.
I've modified two internal flight modes for to enable soaring:
FLY By Wire 'A' I've modified this mode to incorporate a thermal hunting mode based on rate of climb.
Auto Similarly, I've added the same thermal hunting algorithm allowing the plane to fly a planned mission, stopping along the way to circle if ArduPilot senses a rate of climb above the specified value.
I've included only the source code in this repository. You'll have to be familiar with Arduino programming and the Arduino environment to compile and upload the code. Good documentation can again be found on the DIYDrones.com website.
To compile for simulation verses real hardware, see APM_Config.h. There you will find the appropriate #define to turn on / off the hardware in loop (HIL) simulation.
Once the software is compiled and uploaded, connect via the mission planner. You'll notice two new parameters on the advanced parameters page:
SOAR_ACTIVE (0=Soaring disabled and 1=Soaring enabled) THERMAL_VSPEED (thermal speed in m/s that triggers thermal mode)
"SOAR_ACTIVE" is pretty straight forward. "THERMAL_VSPEED" takes a little tuning and is driven by the thermal strength. If you set this value too low, you'll find yourself constantly circling. Set it too low and you'll not stop enough to thermal. You can set the thermal activity in X-Plane by setting it in the "Environment->Weather" menu setting. For initial experimentation, try the following:
In APM Mission Planner: SOAR_ACTIVE 1 (soaring mode enabled) THERMAL_VSPEED (between 2-3 m/s) Don't forget to write parameters to the AP
In X-Plane Environment=>Weather=>Thermal tops = 3500' Environment=>Weather=>Thermal coverage = 10% Environment=>Weather=>Thermal strength = 350' fpm
This should allow you to fly a 30KM or so triangle. I haven't played with downloading real weather or seeing how different winds affect the simulation
- Develop a damper for thermal enter and thermal exit
- Integrate a thermal band, e.g. if you're higher than X feet, don't stop to thermal.
- Intelligent inter-thermal speeds based on lift and / or aircraft polar
- Smarter thermal centering