[Flightgear-users] fgfs as a Ground Control System?
Hi Folks, I am looking forward to something and would want input from all you Flightgear users and developers. If i have not mentioned before, I am a mechanical engineer and an aero-modeler. I have also been a electronics hobbyist since my childhood. I set out to combine my abilities in these areas. Apart from just plain simple model flying i decided to do something more and built some avionics with sensors to put onto my model aircrafts. The embedded software is nearing completion and i am currently working to the communication part of it. Now what follows is the interesting part to me... I would like to use FLightGear as the Ground Control System (GCS) for my aircraft thus throwing it into the class of mini UAV's. My current thoughts supports an ASCII mode and a binary mode of communication. The ASCII mode is much like NMEA protocol. This is the part that i have finished developing (ASCII is easy for debugging ;-)). I am yet to implement the binary mode of communication. In using FlightGear as a GCS, i would like to receive any inputs from fellow users and developers. How complicated would it be to do this. My current thoughts are as follows; I start flightgear with --fdm=external (or NULL; What is the difference?) and set it to receive a generic protocol over the serial port and at say, 4Hz. The generic protocol is suitably written to accept 6 degree of freedom information from my device. Simultaneously, i would like to transmit control surface information which my device will receive and accordingly control the servos onboard. While this just might work, i want to do better than this and hence plan accordingly. I would like to extend the protocol to be more configurable, and interactive. Further, I have video being streamed from onboard the aircraft in an analog form. To convert this i use a TV tuner and interface it with the computer. I got myself an external Pinnacle PCTV USB2 tuner so i can use with a laptop, but unfortunately cant get it to work on linux where i do my development. Anyway, assuming that i get the drivers configured right, i would like to get the video too into FlightGear be it running on any platform. Here is my estimate of what needs to be done to achieve all of this through FlightGear. 1) Add another protocol under Network which can communicate with my hardware and read/modify internal properties appropriately. I will have to add more property values for this device. 2) Add menu items that provide user interface with the hardware. This may not be very difficult as from what i recollect reading, FlightGear provides facility for adding menus etc.? 3) Add parameters to the Headsup Display. This again i remember reading as configurable? 4) Embed a small window where live video is displayed. Preferably it should be possible toggle full screen live Video and embed FlightGears native Scenery display. I should also be able to save the video synchronized with all other property values. I suppose the major challenge is with the 4th point while the rest are relatively easy. Correct me if i am wrong. Another important thing is the FDM. What should i use? I am unable to send all data set in the --native protocol from onboard. Is there a possibility that i fly with the FDM running locally and i only update values that i can? I am not a C++ programmer but a C programmer in the embedded world. I am just stepping into C++ with FlightGear. Any advise,suggestions or guidance that helps is most welcome. FlightGear is truly an amazing piece of work with huge potential. I just want to add one more possibility. Does anybody already use it for such a purpose? -- Cheers! Kitts ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-users] fgfs as a Ground Control System?
Kitts wrote: I am looking forward to something and would want input from all you Flightgear users and developers. If i have not mentioned before, I am a mechanical engineer and an aero-modeler. I have also been a electronics hobbyist since my childhood. I set out to combine my abilities in these areas. Apart from just plain simple model flying i decided to do something more and built some avionics with sensors to put onto my model aircrafts. The embedded software is nearing completion and i am currently working to the communication part of it. Now what follows is the interesting part to me... Hi Kitts, I think there are at least a few others involved in FlightGear that are doing or have plans of doing similar things ... myself included. I actually have two projects in the works. One through the University of Minnesta where I assembled the airframe and am now the chief test pilot (http://www.flightgear.org/~curt/Models/Construction/Rascal110/) and the second is my home project where I have to figure out everything myself (http://www.flightgear.org/~curt/Models/Current/EGN-1/) Do you have any sort of web site for your project or pictures or details of exactly what you are doing? As my own projects progress, I'm becoming increasingly interested in this stuff. I would like to use FLightGear as the Ground Control System (GCS) for my aircraft thus throwing it into the class of mini UAV's. My current thoughts supports an ASCII mode and a binary mode of communication. The ASCII mode is much like NMEA protocol. This is the part that i have finished developing (ASCII is easy for debugging ;-)). I am yet to implement the binary mode of communication. I think this sort of thing is very doable. If you have a gps onboard and can transmit that data to your ground station, that get's you pretty far. You can compute estimates for a lot of the parameters that aren't available directly from the gps. If you pass this data to FlightGear, then you immediately have a system that provides a live synthetic view from the perspective of your UAV. You can also adapt or create a 2d panel which would give you a set of live gauges ... heading, altitude, velocity, rate of climb (est), attitude (est). You could do this as old style steam gauges, you could do it as a hud, or even possibly a modern looking glass cockpit, or all of the above. In using FlightGear as a GCS, i would like to receive any inputs from fellow users and developers. How complicated would it be to do this. My current thoughts are as follows; I start flightgear with --fdm=external (or NULL; What is the difference?) --fdm=null is the proper form, --fdm=external is the same thing and is there for historical reasons. and set it to receive a generic protocol over the serial port and at say, 4Hz. The generic protocol is suitably written to accept 6 degree of freedom information from my device. Simultaneously, i would like to transmit control surface information which my device will receive and accordingly control the servos onboard. Ahh, ok, so you want to live dangerously! This I think is doable, although I'd be a bit worried about latencies and lags and the PIO's that might result if you aren't careful. If it was me, I'd at least make the system self stable (IR co-pilot, or something gyro based) so that I wouldn't have to manually keep the wings level or hold a particular pitch or speed. The ground station could send higher level commands like fly to such and such waypoint, or hold such and such heading and altitude ... While this just might work, i want to do better than this and hence plan accordingly. I would like to extend the protocol to be more configurable, and interactive. There has been discussion of implimenting an xml configurable binary format. That doesn't help you if you want to adjust the fields in real time, but I'm not sure you want to add that kind of complexity to a system where a very small bug can ruin your day/week/month. Further, I have video being streamed from onboard the aircraft in an analog form. To convert this i use a TV tuner and interface it with the computer. I got myself an external Pinnacle PCTV USB2 tuner so i can use with a laptop, but unfortunately cant get it to work on linux where i do my development. Anyway, assuming that i get the drivers configured right, i would like to get the video too into FlightGear be it running on any platform. Someone mentioned that they were working on integrating a live video stream into FlightGear. Perhaps you can search the archives, or perhaps they will speak up. I got the impression that they managed to get something working, but that it might have been kind of a hack job specific to their particular needs. No code was submitted to the project that I'm aware of. Here is my estimate of what needs to be done to achieve all of this through FlightGear. 1) Add another protocol
Re: [Flightgear-users] fgfs as a Ground Control System?
On Tuesday 21 Jun 2005 9:08 pm IST, Curtis L. Olson wrote: CL Kitts wrote: CL CL I am looking forward to something and would want input from all you CL Flightgear users and developers. CL CL If i have not mentioned before, I am a mechanical engineer and an CL aero-modeler. I have also been a electronics hobbyist since my childhood. I CL set out to combine my abilities in these areas. CL CL Apart from just plain simple model flying i decided to do something more and CL built some avionics with sensors to put onto my model aircrafts. The CL embedded software is nearing completion and i am currently working to the CL communication part of it. Now what follows is the interesting part to me... CL CL CL CL Hi Kitts, CL CL I think there are at least a few others involved in FlightGear that are CL doing or have plans of doing similar things ... myself included. I CL actually have two projects in the works. One through the University of CL Minnesta where I assembled the airframe and am now the chief test pilot CL (http://www.flightgear.org/~curt/Models/Construction/Rascal110/) and the CL second is my home project where I have to figure out everything myself CL (http://www.flightgear.org/~curt/Models/Current/EGN-1/) Wow! this is some neat work... i too would like to get a web page up and going where i shall publish all the crazy things i do! :-) CL Do you have any sort of web site for your project or pictures or details CL of exactly what you are doing? As my own projects progress, I'm CL becoming increasingly interested in this stuff. I do not have any website but i can mail you with all details and pictures that you might be interested in. This indeed is very interesting work. Unfortunately, where i live, necessary equipment is not easily available, which restricts or delays much of my progress. CL I would like to use FLightGear as the Ground Control System (GCS) for my CL aircraft thus throwing it into the class of mini UAV's. My current thoughts CL supports an ASCII mode and a binary mode of communication. The ASCII mode CL is much like NMEA protocol. This is the part that i have finished CL developing (ASCII is easy for debugging ;-)). I am yet to implement the CL binary mode of communication. CL CL CL CL I think this sort of thing is very doable. If you have a gps onboard CL and can transmit that data to your ground station, that get's you pretty CL far. You can compute estimates for a lot of the parameters that aren't CL available directly from the gps. If you pass this data to FlightGear, This is pretty much what i want to do. I have a GPS onboard but i do not send data as is received from the GPS but format it and generate packets of data to my interest and send it. The data rate is however, low at a maximum of 4Hz for Position (GPS) and about 10Hz for orientation. This causes Flightgear to not produce a smooth view. I was wondering if there could be a way to extrapolate data and correct it as new data is received. This i understand can be pretty bad if error of extrapolation was large. This could be lessened by flying in FlightGear, an aircraft model similar in performance with the real one. CL then you immediately have a system that provides a live synthetic view CL from the perspective of your UAV. You can also adapt or create a 2d CL panel which would give you a set of live gauges ... heading, altitude, CL velocity, rate of climb (est), attitude (est). You could do this as old CL style steam gauges, you could do it as a hud, or even possibly a modern CL looking glass cockpit, or all of the above. I would prefer a glass cockpit display with HUD as i find it most comfortable to read. But i need analog control and hence a Joystick and never a Keyboard! :-) CL In using FlightGear as a GCS, i would like to receive any inputs from fellow CL users and developers. How complicated would it be to do this. My current CL thoughts are as follows; CL CL I start flightgear with --fdm=external (or NULL; What is the difference?) CL CL CL CL --fdm=null is the proper form, --fdm=external is the same thing and is CL there for historical reasons. Hmmm... Thought so. I found no difference using either. CL and set it to receive a generic protocol over the serial port and at say, CL 4Hz. The generic protocol is suitably written to accept 6 degree of freedom CL information from my device. CL CL Simultaneously, i would like to transmit control surface information which CL my device will receive and accordingly control the servos onboard. CL CL CL CL Ahh, ok, so you want to live dangerously! This I think is doable, CL although I'd be a bit worried about latencies and lags and the PIO's PIO's? CL that might result if you aren't careful. If it was me, I'd at least CL make the system self stable (IR co-pilot, or something gyro based) so CL that I wouldn't have to manually keep the wings level or hold a CL particular
Re: [Flightgear-users] fgfs as a Ground Control System?
Kitts wrote: PIO's? Pilot induced oscillations ... CL I would just run with --fdm=null and pass in the CL data that you do have. Optionally you can compute estimates for things CL you don't have just to make the display prettier. Optionally i can compute? How? Is it not the FDM that does all that computation? The thing you have to remember about the FDM's is that they are self contained units that maintain their own internal state. They aren't setup to have their internal values overridden by an external source, and there are issues and problems doing that. For instance if you estimate some sequence of positions over a second or two, but you were hit with a gust and ended up a long ways off from the estimate, now you plug those new values into the FDM, it sees a huge distance travelled compaired to the estimate in a very short time frame, and might generate huge forces that could ripple through the future calculates and throw your estimates off even further. You almost need a way to check point the calculations so you can backup to the last known good value when your next good data arrives. It's not trivial, there are a ton of pitfalls, and our FDM's aren't setup to be able to do that. Having said that, I don't think any of these things are insurmountable, and there might even be easy solutions to many of the challenges, but you'd have to go dig into the flight model code with a certain level of understanding of what you are doing and what you hope to accomplish before you are going to have any success with this approach. I have used 3 devices till date to achieve wireless link. I have used RF modules from Linx (http://www.linxtechnologies.com/index.php?section=productscategory=rf_modulessubcategory=es_series), BIM1 modules from Radiometrix (http://www.radiometrix.co.uk/products/bim1.htm) and XStream radio modems from maxstream (http://www.maxstream.net/products/xstream/module/9xstream.php). Of the three, the maxstream module is what i currently use as it has provided me with the most reliable link and longest range. I have however, had reasonably good success with the BIM1 modules. It however requires robust error checking algorithms for reliable use. These have the advantage of being light weight and giving pretty good range. Where can I find a price or someone selling the maxstream module? I'm must be missing the link, or do they not sell to individuals? Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-users] fgfs as a Ground Control System?
Curtis L. Olson wrote: Kitts wrote: CL I would just run with --fdm=null and pass in the CL data that you do have. Optionally you can compute estimates for things CL you don't have just to make the display prettier. Optionally i can compute? How? Is it not the FDM that does all that computation? The thing you have to remember about the FDM's is that they are self contained units that maintain their own internal state. They aren't setup to have their internal values overridden by an external source, and there are issues and problems doing that. It might be an idea to extend the ACMS FDM, it takes some inputs (I have to lookup which ones, but I think it's at least lat, lon, speed and direction) and continues to fly until the next update. Erik ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-users] fgfs as a Ground Control System?
On Wednesday 22 Jun 2005 12:27 am IST, Curtis L. Olson wrote: CL Kitts wrote: CL CL PIO's? CL CL CL CL Pilot induced oscillations ... Oh! ok. Yeah this happens all the time when i use the keyboard in the simulator! :-) CL CL I would just run with --fdm=null and pass in the CL CL data that you do have. Optionally you can compute estimates for things CL CL you don't have just to make the display prettier. CL CL Optionally i can compute? How? Is it not the FDM that does all that CL computation? CL CL CL CL The thing you have to remember about the FDM's is that they are self CL contained units that maintain their own internal state. They aren't CL setup to have their internal values overridden by an external source, CL and there are issues and problems doing that. For instance if you CL estimate some sequence of positions over a second or two, but you were CL hit with a gust and ended up a long ways off from the estimate, now you CL plug those new values into the FDM, it sees a huge distance travelled CL compaired to the estimate in a very short time frame, and might generate CL huge forces that could ripple through the future calculates and throw CL your estimates off even further. CL CL You almost need a way to check point the calculations so you can backup CL to the last known good value when your next good data arrives. CL CL It's not trivial, there are a ton of pitfalls, and our FDM's aren't CL setup to be able to do that. CL CL Having said that, I don't think any of these things are insurmountable, CL and there might even be easy solutions to many of the challenges, but CL you'd have to go dig into the flight model code with a certain level of CL understanding of what you are doing and what you hope to accomplish CL before you are going to have any success with this approach. Hmmm... Maybe not right away but as a future thing. For the near future ill stick to --fdm=NULL :-) CL I have used 3 devices till date to achieve wireless link. I have used RF CL modules from Linx CL (http://www.linxtechnologies.com/index.php?section=productscategory=rf_modulessubcategory=es_series), CL BIM1 modules from Radiometrix CL (http://www.radiometrix.co.uk/products/bim1.htm) and XStream radio modems CL from maxstream CL (http://www.maxstream.net/products/xstream/module/9xstream.php). CL CL Of the three, the maxstream module is what i currently use as it has CL provided me with the most reliable link and longest range. I have however, CL had reasonably good success with the BIM1 modules. It however requires CL robust error checking algorithms for reliable use. These have the advantage CL of being light weight and giving pretty good range. CL CL CL CL Where can I find a price or someone selling the maxstream module? I'm CL must be missing the link, or do they not sell to individuals? Price is available on Digikey. Search for Xstream and follow that link RF Transmitters/REceivers. There are plenty of variants available in 2 frequencies. Here is one such variant http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=195594Row=517830Site=US -- Cheers! Kitts ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-users] fgfs as a Ground Control System?
Kitts, Your idea is an interesting one, and I would be interested is hearing about anything that comes of it. I am working on a UAV project at Virginia Commonwealth University where we have made use of FlightGear for test purposes to fly our plane, hardware in the loop, on the simulator. Essentially, we wrote an application that would forward control positions from the on-board flight control system received in telemetry into flight gear, and we would use the position and velocity data from the flight gear FDM to generate fake GPS reports that we sent to the plane in place of the GPS receiver. I did consider using Flight Gear as a feed back tool while we were actually in flight, but we didn't really have the time or the right sensor information. We are using the same Co-Pilot system Curtis is using in his project and GPS for navigation, so we don't have any real attitude (pitch, roll, yaw) information, and we only get position and velocity updates once per second. We are working towards a system with rate gyros and barometric altitude/airspeed sensors, and may consider integrating flight gear further with our ground control station. I do intend to create a website and publish a couple of papers about the project, but I am waiting until after the competition we are preparing for (in 2 weeks) before doing so. I will drop a note on the list about it when it is available in case anyone wants to take a look. -Jeff ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-users] fgfs as a Ground Control System?
On Wednesday 22 Jun 2005 1:35 am IST, Jeff McBride wrote: JM Kitts, JM JM Your idea is an interesting one, and I would be interested is hearing JM about anything that comes of it. Thanks. Much has been done on the onboard side of this project. Soon i will have to concentrate on the Ground Control part of it which is the challenge for me. I need to gather a good understanding of the internals of FlightGear and improve my programming skills in C++. I just know that it is logically possible to do what i have in mind and set forth to do it. JM I am working on a UAV project at Virginia Commonwealth University where JM we have made use of FlightGear for test purposes to fly our plane, JM hardware in the loop, on the simulator. Essentially, we wrote an JM application that would forward control positions from the on-board JM flight control system received in telemetry into flight gear, and we JM would use the position and velocity data from the flight gear FDM to JM generate fake GPS reports that we sent to the plane in place of the JM GPS receiver. How well does this work considering that real world weather conditions are very different from those in the simulator? Control surface responses are never similar? JM I did consider using Flight Gear as a feed back tool while we were JM actually in flight, but we didn't really have the time or the right JM sensor information. We are using the same Co-Pilot system Curtis is JM using in his project and GPS for navigation, so we don't have any real JM attitude (pitch, roll, yaw) information, and we only get position and JM velocity updates once per second. We are working towards a system with JM rate gyros and barometric altitude/airspeed sensors, and may consider JM integrating flight gear further with our ground control station. JM JM I do intend to create a website and publish a couple of papers about the JM project, but I am waiting until after the competition we are preparing JM for (in 2 weeks) before doing so. I will drop a note on the list about JM it when it is available in case anyone wants to take a look. I, for one, would sure like to look at it. Looking at others work can spark new ideas and put them into perspective... -- Cheers! Kitts ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
