Podcast Episode 17 - Curtis Olson on simulators

iTunes links
AAC: http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=33...
MP3: http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=33...

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MP3: http://feeds.feedburner.com/diydronesmp3

Curtis explains some of the many uses of simulators including how a closed loop hardware-in-the-loop system works.


Curtis' profile on DIY Drones: http://diydrones.com/profile/CurtOlson


Flight Gear: http://www.flightgear.org/


Airframe modeling webpage mentioned during the show: http://jsbsim.sourceforge.net/aeromatic.html

Views: 157

Comment by David Ankers on February 23, 2010 at 3:17am
As people might be aware, OpenPilot was announced on the previous DIYDrones PodCast and we are looking for someone to create a Quad model for Flight Gear, this PodCast was very timely as we are currently talking about Hardware in the loop simulations.

Maybe there is a Quad Rotor model already? Any thoughts anyone, would this be possible? I have flown Helis in FlightGear a while ago so it does support rotary aircraft.

We are planning to use the the USB port on OpenPilot to interface with the PC running the sim if possible.

3D Robotics
Comment by Chris Anderson on February 23, 2010 at 7:11am
Here is FMS, the open source RC airplane simulator that automatik was asking about. There are loads of RC aircraft models available for it in the "PAR" file format. Is there any way to convert them to use with FlightGear?
Comment by Curt Olson on February 23, 2010 at 8:59am
Here is a link to the book I briefly mentioned in the interview. Chapters 6 & 7 discuss kalman filtering. Included in the book is a DVD that contains a matlab implementation of a 15 state kalman filter.

http://www.gnssapplications.org/index.html

Title : GNSS Applications And Methods
Editors: Scott Gleason - Demoz Gebre-Egziabher
ISBN-13: 978-1-59693-329-3

Demoz Gebre is an Aerospace Engineeering professor at the University of Minnesota and I have worked with him and his group on a couple different UAV projects over the years.
Comment by Curt Olson on February 23, 2010 at 9:05am
Here is a "sneak peak" at FlightGear v2.0 which is *very* close to being released:

http://www.xs4all.nl/~dtalsma/fgfs2.0/
Comment by David Ankers on February 23, 2010 at 9:58pm
.nl ? Bent u Nederlander? How come a lot of the UAV cool people seem to be Dutch or come from Belgium.
Comment by passunca on February 24, 2010 at 3:05am
nice podcast, I do like the idea to use flight gear as a platform for testing our autopilots. I think using having a setup with two ardupilots is useful but I think we need a complete software solution as well.
What I would like to have is a Ardupilot Emulator/Wrapper that could be used to connect with Flight Gear or any other simulator. What do you guys thinks, is it worth the work?
Comment by Curt Olson on February 24, 2010 at 5:45am
Durk who posted those screenshots is Dutch. We have a few key FlightGear developers who are Dutch (or Dutch now residing in other countries.)
Comment by Curt Olson on February 24, 2010 at 5:49am
Pedro: just my 2 cents here ... I think a full ardupilot emulator would be a huge amount of work if it doesn't already exist. I think you might have better luck compiling the ardupilot code natively for the PC and then adding whatever wrappers/hooks are needed to talk to FlightGear (or your favorite flight simulator.)

The other thing to consider is that autopilot firmware is often very timing critical. Kalman filters and PID controllers are very sensitive to the update rate. This might limit what you could do on a single PC when it gets loaded down with several things running at the same time.
Comment by Curt Olson on February 24, 2010 at 9:04am
Here is a video I made recently of a hardware in the loop test with FlightGear. FlightGear was sending simulated sensor data (gyro, accelerometer, and gps) to the external AP hardware. The hardware was computing a kalman filter estimate of the location and attitude and using that as the input for the autopilot PID stages. The final control surface commands were sent back to FlightGear to actually flight the simulator. The external autopilot was programmed to fly a simple figure 8 pattern over and over again. In FlightGear you can setup an aircraft to drop trajectory markers so you can see the repeatability of your pattern in 3d. You can also emit a smoke trail which is more for fun, or simulating and exploding lipo or something. :-)

http://www.youtube.com/watch?v=yIDQq93cpco
Comment by passunca on February 24, 2010 at 9:55am
Agree, the wrapper is a quicker and easier way to go. It could be used to do mission play back based on the data logged by autopilot (or Ground Station). but it could have a lot more potential uses.
A emulator is a huge undertaking and I have only found this "solution". I don't know if it has any use for this propose, I haven't tested it yet.

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