Re: [Flightgear-devel] Nasal: airportinfo() question
On Monday, May 09, 2011 11:41:53 AM Curtis Olson wrote: Ultimately, what I'd like to do for my project is have an auto-land gui button that will pop up a list of nearby airports. The user selects the one they want and then a list of runways pops up, perhaps ranked based on the prevailing wind conditions. Then when the destination is chosen, the aircraft flies to the airport, enters the downwind pattern, base, final, lands at exactly the target spot. (Maybe with just a little randomization so we don't wear out the concrete always hitting the exact same spot every time.) Curt and all, this is fairly exactly what I am tasked to do for a research project. We have code to create optimal (I put that in quotes as that obviously lies in the eye of the beholder) trajectories, taking some dynamic limitations into account. We would love to test this code in realistic cockpit scenarios, replicating -- in a perfect world -- for example, the Hudson River landing. Looking for an interface between emergency path planning and the pilot (Curt's auto-land gui) we decided that hacking/altering the CDU would be a reasonable attempt as pilots are familiar with the instrument and how to use it. (That is the reason why I wrote a Nasal based CDU for FlightGear based upon Gijs great work.) So what I would like to ask of you, i.e. people who have toyed around with this idea (or read about it, know about it), is to kindly give me some pointers on where I could learn about current developments in this area or where I could learn about the C/C++ code/api to the navdata base and the route manager. Having written the CDU in Nasal I believe to have a fairly good grasp on the language, however I would prefer to write this lower level stuff in C++. Not only because I believe that I/we will need the computational benefit, but also as this might make it easier to contribute more of the code (as a potential closed source library) to more interested parties - although I do promise to try to get as much of my/our work to be open sourced. I am looking forward to hearing from you with pointers to documentation, examples, helpful source files - all that good stuff that could get me up to speed quickly (as I haven't touched the C code of FG yet.) Regards, Claus -- Claus Christmann, M.S. Graduate Research Assistant Georgia Institute of Technology 270 Ferst Dr NW Atlanta, GA 30332-0150 http://uav.ae.gatech.edu -- Achieve unprecedented app performance and reliability What every C/C++ and Fortran developer should know. Learn how Intel has extended the reach of its next-generation tools to help boost performance applications - inlcuding clusters. http://p.sf.net/sfu/intel-dev2devmay ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Nasal: airportinfo() question
On Wed, May 11, 2011 at 8:04 AM, Claus Christmann wrote: Curt and all, this is fairly exactly what I am tasked to do for a research project. We have code to create optimal (I put that in quotes as that obviously lies in the eye of the beholder) trajectories, taking some dynamic limitations into account. We would love to test this code in realistic cockpit scenarios, replicating -- in a perfect world -- for example, the Hudson River landing. Looking for an interface between emergency path planning and the pilot (Curt's auto-land gui) we decided that hacking/altering the CDU would be a reasonable attempt as pilots are familiar with the instrument and how to use it. (That is the reason why I wrote a Nasal based CDU for FlightGear based upon Gijs great work.) So what I would like to ask of you, i.e. people who have toyed around with this idea (or read about it, know about it), is to kindly give me some pointers on where I could learn about current developments in this area or where I could learn about the C/C++ code/api to the navdata base and the route manager. Having written the CDU in Nasal I believe to have a fairly good grasp on the language, however I would prefer to write this lower level stuff in C++. Not only because I believe that I/we will need the computational benefit, but also as this might make it easier to contribute more of the code (as a potential closed source library) to more interested parties - although I do promise to try to get as much of my/our work to be open sourced. I am looking forward to hearing from you with pointers to documentation, examples, helpful source files - all that good stuff that could get me up to speed quickly (as I haven't touched the C code of FG yet.) Hi Claus, So far I've been prototyping all my trajectory planning and management in nasal, but I will eventually migrate that over to C/C++ so I can run on a real embedded computer on a real UAS. I'm glad you put optimal in quotes. :-) There are so many *different* things you could optimize for and all it takes would be 1 or 2 seconds late entering a turn, or a few degrees off on your bank angle, a slight mis-estimate of physics or speed, or a slight mis-estimate of wind and you could come up short of the runway. If you build in too much margin for safety and have slight errors in the opposite direction you could end up overrunning your target landing spot. FlightGear is an awesome tool for testing all this out though ... the proof is in the pudding so to speak, and these are exactly the sorts of challenges that are perfect for testing in a flight simulator. In my case I'm focused more on plotting a landing trajectory that looks and feels intelligent, looks direct, looks solid (the safe ultimate completion of the maneuver is never in doubt) :-) and doesn't waste a ton of extra time or energy. If you know *exactly* the logic that will give you the optimal result, then going straight to C++ is probably fine. For myself, I'm thinking this through as I go, testing different ideas, and observing the results ... so in my case prototyping the logic in nasal is a really great step. I've added trajectory markers and smoke to my UAV model so I can visualize the absolute flight path and see it relative to the wind as well. It's quite a nice tool for exposing suboptimal strategies and for understanding what needs to be fixed and why. I have also been playing with different wind vectors and different amounts of turbulence. I've found that with real uav flight, I never achieve the rock solid perfect results I can see in the sim, even with the exact same flight control code. But if I turn on just a little bit of turbulence, what I see in the sim seems to really align with the results I see in real life. A simulation is a great tool, but at the end of the day, it needs to correlate with reality in certain important ways. Best regards, Curt. -- Curtis Olson: http://www.atiak.com - http://aem.umn.edu/~uav/ http://www.flightgear.org - http://gallinazo.flightgear.org -- Achieve unprecedented app performance and reliability What every C/C++ and Fortran developer should know. Learn how Intel has extended the reach of its next-generation tools to help boost performance applications - inlcuding clusters. http://p.sf.net/sfu/intel-dev2devmay___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
[Flightgear-devel] Nasal: airportinfo() question
Hi, I see that for Nasal scripts we can call airportinfo() to get the name and runway info for the closest airport. We can also call airportinfo(ID) to get the details of a specific airport. However, what I don't see is a way to request a list of the n closest airports (or the airports within a specified radius of my current location.) Is this (or something similar) possible to do within nasal? I'm playing around with an auto-land script and sometimes when you are flying in an area with several airports near by, the airport that is technically the closest to you, might not be the one you are interested in. Thanks, Curt. -- Curtis Olson: http://www.atiak.com - http://aem.umn.edu/~uav/ http://www.flightgear.org - http://gallinazo.flightgear.org -- WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Nasal: airportinfo() question
It does appear that the FGPositioned interface offers everything we would need. I don't know about optimization issues, but it can return a list of all the airports within a certain radius of your current location (or any arbitrary location.) I also see a function that will sort by distance. Then if the user selects a specific airport, airportinfo() already has the functionality to return all the airport details. I see that the current airportinfo() function calls FGAirport class methods which are wrappers around the FGPositioned classes. I'm not sure exactly why that is unless it's related to finding the right instance of the database. I haven't dug too deeply into the code. Martin is right, we could probably slap something together pretty quickly, but it might make more sense for James or someone else more familiar with this code to put together a solid sensible structure and make sure all the pieces tie together in a logical consistent manner. That's probably not me, at least not this week. Perhaps in the future if this is still an open issue and the need rises up higher on my priority list, I'll dig in and make an attempt. Ultimately, what I'd like to do for my project is have an auto-land gui button that will pop up a list of nearby airports. The user selects the one they want and then a list of runways pops up, perhaps ranked based on the prevailing wind conditions. Then when the destination is chosen, the aircraft flies to the airport, enters the downwind pattern, base, final, lands at exactly the target spot. (Maybe with just a little randomization so we don't wear out the concrete always hitting the exact same spot every time.) Best regards, Curt. On Mon, May 9, 2011 at 9:10 AM, Scott wrote: James Turner and I had a bit of a e.mail conversation about this some time ago. My (non-existant) C++ skills aren't up to writing anything, but James thought everything was in the underlying code, and shouldn't be too difficult to expose to Nasal. I've had three disk failure since that time, so I've lost the e.mail thread, but we did define quite a few wishlist functions. BTW I didn't know you could get the closest airport, that is still quite handy for some scenarios, but getting all airports within a radius of a specified geo-coord is even more useful. Scott. On Monday 09 May 2011 23:45:04 Curtis Olson wrote: Hi, I see that for Nasal scripts we can call airportinfo() to get the name and runway info for the closest airport. We can also call airportinfo(ID) to get the details of a specific airport. However, what I don't see is a way to request a list of the n closest airports (or the airports within a specified radius of my current location.) Is this (or something similar) possible to do within nasal? I'm playing around with an auto-land script and sometimes when you are flying in an area with several airports near by, the airport that is technically the closest to you, might not be the one you are interested in. Thanks, Curt. -- WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Curtis Olson: http://www.atiak.com - http://aem.umn.edu/~uav/ http://www.flightgear.org - http://gallinazo.flightgear.org -- WhatsUp Gold - Download Free Network Management Software The most intuitive, comprehensive, and cost-effective network management toolset available today. Delivers lowest initial acquisition cost and overall TCO of any competing solution. http://p.sf.net/sfu/whatsupgold-sd___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
