Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
Am Montag, den 03.12.2007, 00:29 +0100 schrieb STenyaK (Bruno Gonzalez): Ok, thanks. I've thinked a bit more about this whole idea and, since i was planning to code Motorsport as a library instead of as a standalon executable, maybe Motorsport can be used from FlightGear, instead of being coded inside it. It looks like FG already uses several different physics engines depending on the planes (am i right?), so it would be a matter of adding another one for land vehicles. How does that sound? This sounds good to me, I would really appreciate a car FDM. Especially, if it can interact with the aircraft (towing or pushback, or even load cars into aircraft). Your project would benefit from the worldwide scenery (e.g for the Rallye Paris Dakar) and multiplayer capability. On 12/1/07, Detlef Faber [EMAIL PROTECTED] wrote: Am Samstag, den 01.12.2007, 18:39 +0100 schrieb STenyaK (Bruno Gonzalez): I'm unable to find the Jeep or any other car that were mentioned.. haven't searched much though. Try this: http://sol2500.net/flightgear/jeep.zip It should work with 0.9.10, but you will not have different ground properties like the FlightGear CVS version has. Quick question: by ground reactions you mean collision detection and response? Are there no plane-to-plane collisions currently, only basic plane-to-ground? And is the ground a generic trimesh or a heightmap? On 12/1/07, Jon S. Berndt [EMAIL PROTECTED] wrote: GWMobile wrote: Just to help you. X-plane simulates springs and tires and has an open interface. People have built cars for x-plane. The roads suck though. I think it would be great if fgear did this too. Ground reactions have been a hot topic for a while. It sounds like Andy has got something really nice for YASim, and I hope to get time to look at that code at some point very soon. Obviously, people look at simulations differently, and there are a lot of sims out there that serve different purposes. To the dismay of some here, we haven't paid so much attention to ground reactions with JSBSim. First and foremost is because I don't have the time I once did. Second, it's because my own focus is more on the GNC aspects, and overall sim architecture, as well as other things. At some point, I hope to revisit the ground reactions code. Jon - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
On 12/3/07, Detlef Faber [EMAIL PROTECTED] wrote: Am Montag, den 03.12.2007, 00:29 +0100 schrieb STenyaK (Bruno Gonzalez): It looks like FG already uses several different physics engines depending on the planes (am i right?), so it would be a matter of adding another one for land vehicles. This sounds good to me, I would really appreciate a car FDM. Especially, if it can interact with the aircraft (towing or pushback, or even load cars into aircraft). I'm not sure what FDM means, couldnt' find a good explanation. It looks like it's what i call a physics engine. Are there any existing examples of several FDMs interacting with each other? Planes colliding with other planes, or their turbulences affecting the other, etc.? An FDM that uses Motorsport physics could be easily created, but the interaction between several FDMs is another issue... Your project would benefit from the worldwide scenery (e.g for the Rallye Paris Dakar) and multiplayer capability. I'm still not sure if that kind of features would be included in the Motorsport core, or provided by a third party program (such as FG), we're still in the design stages of the project. -- Saludos, Bruno González ___ Msn/Jabber: stenyak AT gmail.com ICQ: 153709484 http://www.stenyak.com - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
On Dec 3, 2007 6:23 AM, STenyaK (Bruno Gonzalez) wrote: I'm not sure what FDM means, couldnt' find a good explanation. FDM is the acronym we use for flight dynamics model. Conceptually, a physics engine engine covers much of the same ground. If I were to get really nitpicky, perhaps I could say that the flight dynamics model contains a physics engine + additional speciallized code to model the dynamics of flight. It looks like it's what i call a physics engine. Are there any existing examples of several FDMs interacting with each other? Planes colliding with other planes, or their turbulences affecting the other, etc.? So far in the flightgear project we have not addressed aircraft/vehicles affecting each other. Our philosophy is that we are modeling a friendly airspace so collisions with other aircraft should never ... at least for those that take their simming seriously and start somewhere other than the default location. It would be interesting to model turbulence affects from one aircraft/vehicle onto another, but to do this in a generic and physically correct way, might be far beyond the scope of what we can accomplish with finite compute power. Maybe we could build in some interesting heuristics/hacks though that could be fun. In the world of aviation we have wake turbulence, formation flying (and air to air refueling, aero towing, etc.) An FDM that uses Motorsport physics could be easily created, but the interaction between several FDMs is another issue... The FlightGear FDM interface was originally designed so it is relatively straight forward to drop in another physics engine. (sorry to mix terms there.) :-) I'm still not sure if that kind of features would be included in the Motorsport core, or provided by a third party program (such as FG), we're still in the design stages of the project. I've always thought it would be fun to wind through an interesting mountain region for a hundred miles or so of realistic roadway with real terrain, etc. The driving sims I've seen have either stuck with specific race tracks or very small areas with lots of detail, or larger areas with very sparse detail. Algorithmically it would be possible to create large areas with pretty nice detail. I've been dabbling in some of that recently, but it's really hard stuff. Intersections are hard to deal with, the complexity and polygon count of detailed roadways are hard to handle, and creating realistic surfaces from noisy SRTM data is also a difficult thing to do. But there are some tantalizing ideas that wouldn't be all that hard. If you added some attributes to your road data base, you could start dropping in things like mile markers, street lights, other regularly spaced signs, mail boxes, guard rails, jerzey barrier. My problem is that I have way more good ideas than I have time. Well at least I think they are good ideas. :-) Curt. -- Curtis Olson: http://baron.flightgear.org/~curt/ Unique text: 2f585eeea02e2c79d7b1d8c4963bae2d - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
On 12/03/2007 08:32 AM, Curtis Olson wrote: An FDM that uses Motorsport physics could be easily created, but the interaction between several FDMs is another issue... Consider the PBY Catalina or other amphibian: -- When it's in the air, it's an aircraft. -- When it's on the water, it's a boat. -- When it's on land, it's a vehicle. I don't recommend it, but these could be treated as three separate problems, with three separate dynamics models ... but what we really need is a unified dynamics model that can handle all three cases in a consistent way. Obviously air loads *and* tire loads are important for cars. Ditto for aircraft on the ground. Obviously you need to model the air *and* the water for sailboats. And while an amphibian is crawling out of the water onto land, it is in all three worlds at once. I don't much care what you call it. -- On this list heretofore, it has usually been called the flight dynamics model (FDM). -- In the world of boats, it is called the fluid dynamics model (again FDM). -- As soon as we have tires on pavement, those names are no longer apt. -- You can also have a structural dynamics model. Alternatives include plain old Dynamics Model (DM or DyMo) or of course Physics Engine (PhEng). Beware that there is a huge legacy here; there are nearly ten thousand mentions of the term FDM in the flightgear file tree, so even though the term isn't apt, it is going to remain with us for quite a while. In the interests of backward compatibility, it might be simplest to declare that FDM stands for Fine Dynamics Model (as in RTFM == Read the Fine Manual), and declare that the ideal FDM should include air, water, tires, and mechanical interactions. Going forward, Physics Engine' is as good a name as any, and is consistent with usage in the rest of the modeling community. - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
On 12/3/07, Curtis Olson [EMAIL PROTECTED] wrote: On Dec 3, 2007 6:23 AM, STenyaK (Bruno Gonzalez) wrote: I'm not sure what FDM means, couldnt' find a good explanation. FDM is the acronym we use for flight dynamics model. Conceptually, a physics engine engine covers much of the same ground. If I were to get really nitpicky, perhaps I could say that the flight dynamics model contains a physics engine + additional speciallized code to model the dynamics of flight. Ok, it's what i thought. Personally, i call physics engine to everything that models real world physics, no matter if they have to deal with air, water, terrain, outter space or whatever. But I'm not interested in the naming each community gives to it, just in its meaning :-) So far in the flightgear project we have not addressed aircraft/vehicles affecting each other. Our philosophy is that we are modeling a friendly airspace so collisions with other aircraft should never ... at least for those that take their simming seriously and start somewhere other than the default location. It would be interesting to model turbulence affects from one aircraft/vehicle onto another, but to do this in a generic and physically correct way, might be far beyond the scope of what we can accomplish with finite compute power. Maybe we could build in some interesting heuristics/hacks though that could be fun. In the world of aviation we have wake turbulence, formation flying (and air to air refueling, aero towing, etc.) In the world of racesims, car-to-car collisions are pretty important and common, as is car-to-track collision (both driving surface, walls, tire piles, sand, cones, etc). I'm not a physics expert, in fact i'm crap at maths and physics (compared to many people), so it's not my intention to even try to merge 2 physics engines together, when i can barely create one of them myself :-) By merging, i mean the mentioned idea of allowing a car to tow a plane, each of which would have its own FDM. My intention is to provide a good framework where knowledgeable people can contribute code to. That has been the case of several university students, one of which added drivetrain physics to the old version of Motorsport. Another one coded genetic-evolutive AI that drived around tracks. Also i've been approached by people working for the DARPA Challenge, in order to use Motorsport for the last urban challenge project. I'm good at computers and programming, so that's what i try to contribute with. For example, P2P distribution of contents, streaming of gEarth or WorldWind or FlightGear terrain data... Well, the kind of things that i know how to code. The FlightGear FDM interface was originally designed so it is relatively straight forward to drop in another physics engine. (sorry to mix terms there.) :-) Good, since the Motorsport remake is also planned to be easy to drop into other games/programs/simulators. I've always thought it would be fun to wind through an interesting mountain region for a hundred miles or so of realistic roadway with real terrain, etc. The driving sims I've seen have either stuck with specific race tracks or very small areas with lots of detail, or larger areas with very sparse detail. Algorithmically it would be possible to create large areas with pretty nice detail. I've been dabbling in some of that recently, but it's really hard stuff. Intersections are hard to deal with, the complexity and polygon count of detailed roadways are hard to handle, and creating realistic surfaces from noisy SRTM data is also a difficult thing to do. But there are some tantalizing ideas that wouldn't be all that hard. If you added some attributes to your road data base, you could start dropping in things like mile markers, street lights, other regularly spaced signs, mail boxes, guard rails, jerzey barrier. My problem is that I have way more good ideas than I have time. Well at least I think they are good ideas. :-) The problem is that heaps of detail are needed in order to make it enjoyable or realistic. The air is reasonably constant, so if i'm not mistaken, there's not much need to model differences in pressures or temperatures or things like that. Plus you have 6 degrees of freedom to play with. In the case of cars, you're limited to following a road (with the occasional jumps, which are interesting if taking gyroscopic effects into account), and so the driving surface needs good detail or it'll be boring to drive. Potholes, camber, different leves of adherence in different places, materials, weather conditions, temperatures, etc. I've also thought about automatic generation of roads (i implemented a 4D-Stunts track loader in the old Motorsport as a first approach), but there's still a long way to go before any result is good enough. I'll only concentrate on allowing data streaming for now, procedural roads will still wait for some years (unless someone steps in and codes it sooner, of course).
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
Ok, thanks. I've thinked a bit more about this whole idea and, since i was planning to code Motorsport as a library instead of as a standalon executable, maybe Motorsport can be used from FlightGear, instead of being coded inside it. It looks like FG already uses several different physics engines depending on the planes (am i right?), so it would be a matter of adding another one for land vehicles. How does that sound? On 12/1/07, Detlef Faber [EMAIL PROTECTED] wrote: Am Samstag, den 01.12.2007, 18:39 +0100 schrieb STenyaK (Bruno Gonzalez): I'm unable to find the Jeep or any other car that were mentioned.. haven't searched much though. Try this: http://sol2500.net/flightgear/jeep.zip It should work with 0.9.10, but you will not have different ground properties like the FlightGear CVS version has. Quick question: by ground reactions you mean collision detection and response? Are there no plane-to-plane collisions currently, only basic plane-to-ground? And is the ground a generic trimesh or a heightmap? On 12/1/07, Jon S. Berndt [EMAIL PROTECTED] wrote: GWMobile wrote: Just to help you. X-plane simulates springs and tires and has an open interface. People have built cars for x-plane. The roads suck though. I think it would be great if fgear did this too. Ground reactions have been a hot topic for a while. It sounds like Andy has got something really nice for YASim, and I hope to get time to look at that code at some point very soon. Obviously, people look at simulations differently, and there are a lot of sims out there that serve different purposes. To the dismay of some here, we haven't paid so much attention to ground reactions with JSBSim. First and foremost is because I don't have the time I once did. Second, it's because my own focus is more on the GNC aspects, and overall sim architecture, as well as other things. At some point, I hope to revisit the ground reactions code. Jon - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Saludos, Bruno González ___ Msn/Jabber: stenyak AT gmail.com ICQ: 153709484 http://www.stenyak.com - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
Just to help you. X-plane simulates springs and tires and has an open interface. People have built cars for x-plane. The roads suck though. I think it would be great if fgear did this too. On Fri, 30 Nov 2007 5:39 pm, STenyaK (Bruno Gonzalez) wrote: I'm not familiar with the suspension geometry of planes, but i *guess* it can be modelled as a series of bodies, joints, springs and dampers, together with the tire model. Planes tires are pretty big, so they're an important part of the suspension process in landings too (and braking.. planes have brakes on their wheels too, not just reversing engines rotation + flaps, right?), not so much in take offs. You simply simulate a couple of bodies linked together through joints, and the springs and dampers must be present too (depends on the physics engine of choice, the spring rates and dampening values are part of the joints properties, or a separate entity). As for the tires, that's probably the biggest issue i'll have to deal with in my simulator, but i think a simple approximation will be enough for plane landings. I was hoping fligh gear simulated all those entity types i've mentioned, since that's what i could reuse for the physics of Motorsport. However, if it does not, then both projects are in need of using a third party physics engine that does it, such as ODE, Bullet, Physsim, etc. (unless you want to code it yourself, but i'm not a physicsist nor a mathematician, and i don't have enough spare time to learn enough, so i try to reuse physics code as much as possible. which is one of the reasons i'm looking into using FG). On 12/1/07, Jon S. Berndt [EMAIL PROTECTED] wrote: Hi all, I'm the main developer of Motorsport ( www.motorsport-sim.org ), a wheeled vehicles simulator (aimed at racing cars, but not necessarily exclusively focused on that). I'm rewriting the sim from scratch, and while i'm at it, i'm reconsidering my choices of third party libraries to use. I've been told that FlighGear people were interested in including a car simulation on it too, so that's why i'm seding this email :-) I am particularly interested in how you model suspension/ground reactions. Jon Jon S. Berndt Development Coordinator JSBSim Project www.JSBSim.org - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Saludos, Bruno González ___ Msn/Jabber: stenyak AT gmail.com ICQ: 153709484 http://www.stenyak.com - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel www.GlobalBoiling.com for daily images about hurricanes, globalwarming and the melting poles. www.ElectricQuakes.com daily solar and earthquake images. - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
Ralf Gerlich wrote: It's probably a good idea to note here that Mathias Fröhlich's OpenFDM is based on such a multibody concept. http://openfdm.berlios.net/ Sorry, don't know how I got to that URL. That's http://developer.berlios.de/projects/openfdm/ of course. Cheers, Ralf - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
STenyaK (Bruno Gonzalez) wrote: I'm not familiar with the suspension geometry of planes, but i *guess* it can be modelled as a series of bodies, joints, springs and dampers, together with the tire model. [SNIP] You simply simulate a couple of bodies linked together through joints, and the springs and dampers must be present too (depends on the physics engine of choice, the spring rates and dampening values are part of the joints properties, or a separate entity). As for the tires, that's probably the biggest issue i'll have to deal with in my simulator, but i think a simple approximation will be enough for plane landings. It's probably a good idea to note here that Mathias Fröhlich's OpenFDM is based on such a multibody concept. http://openfdm.berlios.net/ Cheers, Ralf - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
It was fine when I checked. Had screenshots of the sim. Looked pretty good! On Fri, 30 Nov 2007 6:28 pm, STenyaK (Bruno Gonzalez) wrote: On 12/1/07, Arnt Karlsen [EMAIL PROTECTED] wrote: ..check your site, Bruno. On your Wiki page, I get refs to Britney sex, old man sex, free mature, cheerleaders nude etc, I'm the one using Links right now browsing your site. I know, but thanks anyway. With the remake of Motorsport, I'm also migrating the whole website to a set of web software that's less of a pain in the a. to maintain :) The wiki is temporarilly migrated to the Topics section of motorsport.stenyak.com/tracker. -- Saludos, Bruno González ___ Msn/Jabber: stenyak AT gmail.com ICQ: 153709484 http://www.stenyak.com - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel www.GlobalBoiling.com for daily images about hurricanes, globalwarming and the melting poles. www.ElectricQuakes.com daily solar and earthquake images. - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
Am Freitag, den 30.11.2007, 23:04 -0600 schrieb Curtis Olson: On Nov 30, 2007 10:11 PM, Jon S. Berndt wrote: Some of the engineering sims I use at work (space shuttle) have very detailed models of landing gear and tire spinup, etc. Of course, we don't ever see power trains driving the wheels (at least we don't in JSBSim). There are some simplifications made in our gear model that suffice for modeling what planes do. However, out of curiosity, I am interested to see how ground reactions are modeled for autos - particularly for the case when the vehicle is at rest. I am familiar with Pacejka's magic formula, etc. It can be a complicated problem, so it's useful and interesting to see how others approach the problem. I think it's worth pointing out that in FlightGear cvs we have models of a jeep and of a snowplow (truck). The dynamics are based on YAsim and the wheel/suspension modeling seems to work really well. I was actually very impressed at the sorts of things that YAsim does ... Andy cooked a little bit of physics magic in there some how! Things I notice when playing around with the snowplow: - The suspension at each tire is modeled independently. - The suspension reacts to surface properties ... like smooth pavement, rougher grass, etc. - If you drive into a lake or ocean you sink. - If you drive off a bridge you dive end over end pretty realistically. - When you corner, the individual suspension elements seem to react correctly. The front outside tire seems to dig in as you turn sharper and sharper. - As you corner more and more sharply, you need more power to maintain the same speed. - If you turn too sharply, you can actually roll the vehicle ... and visually, it looks very realistic. - The vehicle reacts to wind. - There is great interaction between the larger vehicle/body dynamics, the individual suspension components, and the surface. The vehicle reacts correctly to slopes and change in terrain. I caught one view where I was driving over the edge of some detailed road I created for a day job project and there was a lot of slope/surface variation in the triangle mesh. Watching this big truck barrel over that with the body and suspension all working together ... visually it looked right on. I wish I would have been able to capture that particular sequence as a movie, but it's one of those sorts of fleeting things and it's difficult to reproduce the exact same sequence of speed, vehicle path, and view point. - So then if you poke around our aircraft fleet, you find a catalina and a beaver on amphibs ... you can literally take off on wheels, retract them, and land on the pontoons, take off and land back on wheels. Oh, and there's a few helicopters available too. So I'm not saying everything is perfect, but it's a pretty darn good little general purpose physics engine. I fully agree, I was surprised when I modeled the Jeep how well the gears and suspension work. What's missing right now is a proper simulation of transmission and gearshift (it's a jet engine right now). IMHO YaSim is a good base to implement any kind of ground/water vehicle FDM. I would also comment that my day job (well until my contract expires in June) [sniff, hand me another box of kleenex ... actually more like break out the champaign] :-) involves taking care of a very expensive commercial driving simulator. In my best estimation, the YAsim based snowplow captures or models many more dynamics effects at a much better detail level and realism than this big fancy driving simulator we use for human factors research. (And we spent close to $250k when it was first installed and probably a couple more $100k in the subsequent years on improved hardware and software.) I think a person could do a lot worse than looking over Andy's shoulder to see how he took care of the gear/suspension/wheel dynamics portion of YAsim ... it's really pretty darn good. Now I'm going to guess he's not modeling things like tire flex and some of the really subtle details some people get into ... there's always room to nitpick anything. I don't bring this up to nitpick, but to fend off the potential nitpickers in advance. :-) Regards, Curt. -- Curtis Olson: http://baron.flightgear.org/~curt/ Unique text: 2f585eeea02e2c79d7b1d8c4963bae2d - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
Sounds like fg is ready to be a road sim then! On Fri, 30 Nov 2007 9:18 pm, Jon S. Berndt wrote: I think it's worth pointing out that in FlightGear cvs we have models of a jeep and of a snowplow (truck). The dynamics are based on YAsim and the wheel/suspension modeling seems to work really well. I was actually very impressed at the sorts of things that YAsim does ... Andy cooked a little bit of physics magic in there some how! Things I notice when playing around with the snowplow: - The suspension at each tire is modeled independently. - The suspension reacts to surface properties ... like smooth pavement, rougher grass, etc. - If you drive into a lake or ocean you sink. - If you drive off a bridge you dive end over end pretty realistically. - When you corner, the individual suspension elements seem to react correctly. The front outside tire seems to dig in as you turn sharper and sharper. - As you corner more and more sharply, you need more power to maintain the same speed. - If you turn too sharply, you can actually roll the vehicle ... and visually, it looks very realistic. - The vehicle reacts to wind. - There is great interaction between the larger vehicle/body dynamics, the individual suspension components, and the surface. The vehicle reacts correctly to slopes and change in terrain. I caught Sounds like a good topic for a technical paper. The next AIAA Modeling and Sim conference is in Honolulu. J Jon www.GlobalBoiling.com for daily images about hurricanes, globalwarming and the melting poles. www.ElectricQuakes.com daily solar and earthquake images. - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
GWMobile wrote: Just to help you. X-plane simulates springs and tires and has an open interface. People have built cars for x-plane. The roads suck though. I think it would be great if fgear did this too. Ground reactions have been a hot topic for a while. It sounds like Andy has got something really nice for YASim, and I hope to get time to look at that code at some point very soon. Obviously, people look at simulations differently, and there are a lot of sims out there that serve different purposes. To the dismay of some here, we haven't paid so much attention to ground reactions with JSBSim. First and foremost is because I don't have the time I once did. Second, it's because my own focus is more on the GNC aspects, and overall sim architecture, as well as other things. At some point, I hope to revisit the ground reactions code. Jon - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
I'm unable to find the Jeep or any other car that were mentioned.. haven't searched much though. Quick question: by ground reactions you mean collision detection and response? Are there no plane-to-plane collisions currently, only basic plane-to-ground? And is the ground a generic trimesh or a heightmap? On 12/1/07, Jon S. Berndt [EMAIL PROTECTED] wrote: GWMobile wrote: Just to help you. X-plane simulates springs and tires and has an open interface. People have built cars for x-plane. The roads suck though. I think it would be great if fgear did this too. Ground reactions have been a hot topic for a while. It sounds like Andy has got something really nice for YASim, and I hope to get time to look at that code at some point very soon. Obviously, people look at simulations differently, and there are a lot of sims out there that serve different purposes. To the dismay of some here, we haven't paid so much attention to ground reactions with JSBSim. First and foremost is because I don't have the time I once did. Second, it's because my own focus is more on the GNC aspects, and overall sim architecture, as well as other things. At some point, I hope to revisit the ground reactions code. Jon - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Saludos, Bruno González ___ Msn/Jabber: stenyak AT gmail.com ICQ: 153709484 http://www.stenyak.com - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
Am Samstag, den 01.12.2007, 18:39 +0100 schrieb STenyaK (Bruno Gonzalez): I'm unable to find the Jeep or any other car that were mentioned.. haven't searched much though. Try this: http://sol2500.net/flightgear/jeep.zip It should work with 0.9.10, but you will not have different ground properties like the FlightGear CVS version has. Quick question: by ground reactions you mean collision detection and response? Are there no plane-to-plane collisions currently, only basic plane-to-ground? And is the ground a generic trimesh or a heightmap? On 12/1/07, Jon S. Berndt [EMAIL PROTECTED] wrote: GWMobile wrote: Just to help you. X-plane simulates springs and tires and has an open interface. People have built cars for x-plane. The roads suck though. I think it would be great if fgear did this too. Ground reactions have been a hot topic for a while. It sounds like Andy has got something really nice for YASim, and I hope to get time to look at that code at some point very soon. Obviously, people look at simulations differently, and there are a lot of sims out there that serve different purposes. To the dismay of some here, we haven't paid so much attention to ground reactions with JSBSim. First and foremost is because I don't have the time I once did. Second, it's because my own focus is more on the GNC aspects, and overall sim architecture, as well as other things. At some point, I hope to revisit the ground reactions code. Jon - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
Hi all, I'm the main developer of Motorsport ( www.motorsport-sim.org ), a wheeled vehicles simulator (aimed at racing cars, but not necessarily exclusively focused on that). I'm rewriting the sim from scratch, and while i'm at it, i'm reconsidering my choices of third party libraries to use. I've been told that FlighGear people were interested in including a car simulation on it too, so that's why i'm seding this email :-) I am particularly interested in how you model suspension/ground reactions. Jon Jon S. Berndt Development Coordinator JSBSim Project www.JSBSim.org - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
On Sat, 1 Dec 2007 00:45:05 +0100, STenyaK wrote in message [EMAIL PROTECTED]: (please excuse me if this is not the correct place to ask this) Hi all, I'm the main developer of Motorsport ( www.motorsport-sim.org ) ..check your site, Bruno. On your Wiki page, I get refs to Britney sex, old man sex, free mature, cheerleaders nude etc, I'm the one using Links right now browsing your site. -- ..med vennlig hilsen = with Kind Regards from Arnt... ;o) ...with a number of polar bear hunters in his ancestry... Scenarios always come in sets of three: best case, worst case, and just in case. - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
I'm not familiar with the suspension geometry of planes, but i *guess* it can be modelled as a series of bodies, joints, springs and dampers, together with the tire model. Planes tires are pretty big, so they're an important part of the suspension process in landings too (and braking.. planes have brakes on their wheels too, not just reversing engines rotation + flaps, right?), not so much in take offs. You simply simulate a couple of bodies linked together through joints, and the springs and dampers must be present too (depends on the physics engine of choice, the spring rates and dampening values are part of the joints properties, or a separate entity). As for the tires, that's probably the biggest issue i'll have to deal with in my simulator, but i think a simple approximation will be enough for plane landings. I was hoping fligh gear simulated all those entity types i've mentioned, since that's what i could reuse for the physics of Motorsport. However, if it does not, then both projects are in need of using a third party physics engine that does it, such as ODE, Bullet, Physsim, etc. (unless you want to code it yourself, but i'm not a physicsist nor a mathematician, and i don't have enough spare time to learn enough, so i try to reuse physics code as much as possible. which is one of the reasons i'm looking into using FG). On 12/1/07, Jon S. Berndt [EMAIL PROTECTED] wrote: Hi all, I'm the main developer of Motorsport ( www.motorsport-sim.org ), a wheeled vehicles simulator (aimed at racing cars, but not necessarily exclusively focused on that). I'm rewriting the sim from scratch, and while i'm at it, i'm reconsidering my choices of third party libraries to use. I've been told that FlighGear people were interested in including a car simulation on it too, so that's why i'm seding this email :-) I am particularly interested in how you model suspension/ground reactions. Jon Jon S. Berndt Development Coordinator JSBSim Project www.JSBSim.org - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel -- Saludos, Bruno González ___ Msn/Jabber: stenyak AT gmail.com ICQ: 153709484 http://www.stenyak.com - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
I'm not familiar with the suspension geometry of planes, but i *guess* it can be modelled as a series of bodies, joints, springs and dampers, together with the tire model. Planes tires are pretty big, so they're an important part of the suspension process in landings too (and braking.. planes have brakes on their wheels too, not just reversing engines rotation + flaps, right?), not so much in take offs. Some of the engineering sims I use at work (space shuttle) have very detailed models of landing gear and tire spinup, etc. Of course, we don't ever see power trains driving the wheels (at least we don't in JSBSim). There are some simplifications made in our gear model that suffice for modeling what planes do. However, out of curiosity, I am interested to see how ground reactions are modeled for autos - particularly for the case when the vehicle is at rest. I am familiar with Pacejka's magic formula, etc. It can be a complicated problem, so it's useful and interesting to see how others approach the problem. Jon - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
On Nov 30, 2007 10:11 PM, Jon S. Berndt wrote: Some of the engineering sims I use at work (space shuttle) have very detailed models of landing gear and tire spinup, etc. Of course, we don't ever see power trains driving the wheels (at least we don't in JSBSim). There are some simplifications made in our gear model that suffice for modeling what planes do. However, out of curiosity, I am interested to see how ground reactions are modeled for autos - particularly for the case when the vehicle is at rest. I am familiar with Pacejka's magic formula, etc. It can be a complicated problem, so it's useful and interesting to see how others approach the problem. I think it's worth pointing out that in FlightGear cvs we have models of a jeep and of a snowplow (truck). The dynamics are based on YAsim and the wheel/suspension modeling seems to work really well. I was actually very impressed at the sorts of things that YAsim does ... Andy cooked a little bit of physics magic in there some how! Things I notice when playing around with the snowplow: - The suspension at each tire is modeled independently. - The suspension reacts to surface properties ... like smooth pavement, rougher grass, etc. - If you drive into a lake or ocean you sink. - If you drive off a bridge you dive end over end pretty realistically. - When you corner, the individual suspension elements seem to react correctly. The front outside tire seems to dig in as you turn sharper and sharper. - As you corner more and more sharply, you need more power to maintain the same speed. - If you turn too sharply, you can actually roll the vehicle ... and visually, it looks very realistic. - The vehicle reacts to wind. - There is great interaction between the larger vehicle/body dynamics, the individual suspension components, and the surface. The vehicle reacts correctly to slopes and change in terrain. I caught one view where I was driving over the edge of some detailed road I created for a day job project and there was a lot of slope/surface variation in the triangle mesh. Watching this big truck barrel over that with the body and suspension all working together ... visually it looked right on. I wish I would have been able to capture that particular sequence as a movie, but it's one of those sorts of fleeting things and it's difficult to reproduce the exact same sequence of speed, vehicle path, and view point. - So then if you poke around our aircraft fleet, you find a catalina and a beaver on amphibs ... you can literally take off on wheels, retract them, and land on the pontoons, take off and land back on wheels. Oh, and there's a few helicopters available too. So I'm not saying everything is perfect, but it's a pretty darn good little general purpose physics engine. I would also comment that my day job (well until my contract expires in June) [sniff, hand me another box of kleenex ... actually more like break out the champaign] :-) involves taking care of a very expensive commercial driving simulator. In my best estimation, the YAsim based snowplow captures or models many more dynamics effects at a much better detail level and realism than this big fancy driving simulator we use for human factors research. (And we spent close to $250k when it was first installed and probably a couple more $100k in the subsequent years on improved hardware and software.) I think a person could do a lot worse than looking over Andy's shoulder to see how he took care of the gear/suspension/wheel dynamics portion of YAsim ... it's really pretty darn good. Now I'm going to guess he's not modeling things like tire flex and some of the really subtle details some people get into ... there's always room to nitpick anything. I don't bring this up to nitpick, but to fend off the potential nitpickers in advance. :-) Regards, Curt. -- Curtis Olson: http://baron.flightgear.org/~curt/ Unique text: 2f585eeea02e2c79d7b1d8c4963bae2d - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
Re: [Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
On 12/1/07, Arnt Karlsen [EMAIL PROTECTED] wrote: ..check your site, Bruno. On your Wiki page, I get refs to Britney sex, old man sex, free mature, cheerleaders nude etc, I'm the one using Links right now browsing your site. I know, but thanks anyway. With the remake of Motorsport, I'm also migrating the whole website to a set of web software that's less of a pain in the a. to maintain :) The wiki is temporarilly migrated to the Topics section of motorsport.stenyak.com/tracker. -- Saludos, Bruno González ___ Msn/Jabber: stenyak AT gmail.com ICQ: 153709484 http://www.stenyak.com - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
[Flightgear-devel] Modifying/Contributing with a wheeled vehicle simulator
(please excuse me if this is not the correct place to ask this) Hi all, I'm the main developer of Motorsport ( www.motorsport-sim.org ), a wheeled vehicles simulator (aimed at racing cars, but not necessarily exclusively focused on that). I'm rewriting the sim from scratch, and while i'm at it, i'm reconsidering my choices of third party libraries to use. I've been told that FlighGear people were interested in including a car simulation on it too, so that's why i'm seding this email :-) If possible, I'd like to get some questions asked (sorted by importance, more or less): - Well, of course the first one is: are you really interested on a possible contribution/modification of flight gear like this? - What does the FG physics engine currently feature?: - Types of collision shapes (meshes, spheres, boxes...) - Automatic computation of their masses/inertia tensors? - Constraints between different rigid bodies (prismatic, revolute, fixed, ... joints). - Aerodynamics simulation... how does it handle it when near the ground? · http://en.wikipedia.org/wiki/Ground_effect_in_cars · http://en.wikipedia.org/wiki/Diffuser_(automotive) - turbulences produced behind bodies (smoke angel in planes, but i'm more interested in reduced drag to other cars, the so-called slipstreaming effect). · and of course, effect of wind on regular car body shapes and wings (close to the main body, or up to about 1 meter above it).. are aero properties calculated on the fly based on a given shape trimesh, like IIRC X-Plane does? Leaving physics aside... - Adaptability of the FG game engine to smaller scoped objects. Will there be problems in increasing ground textures resolution? If needed, will I be able to see a screw in 3D, or maybe the FG LOD system can't be tweaked for that due to design? Etc. - Possibility to add an arbitrary number of inputs (car door lever attached to joystick axis #2, upshift paddle attached to mouse button #1, etc.) and outputs (telemetry of cars, on-screen display of G-forces on the center of mass of the vehicle, relative angles of gas/brake/clutch pedals, engine rpm output to a secondary screen, ...). - Possibility to make those inputs clickable in the render window (click-n-drag the gear shift lever with the mouse, or pull a door handle, or whatever). - Possibility of detaching visualization/sounds from the physic simulation? Those are the main questions i can think about. Sorry for the long list, feel free to only reply a few of them, there's no hurry... Thanks a lot for your time (whether you managed to read everything or not ;-) Regards, -- Saludos, Bruno González ___ Msn/Jabber: stenyak AT gmail.com ICQ: 153709484 http://www.stenyak.com - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
