The online racing simulator
assists and realism in LFS
(122 posts, started )
Quote from atlantian :wow, Lego, sweet, so are u saying that LFSTweak would just screw up the physics if you use it for something minor as trimming a few pounds off?

No, I'm saying that you wouldn't be able to use it on-line if you changed the weight of the car, it would be considered cheating and would get you banned if you did.

Quote from jayhawk :That is a lovely set. Perfect gearing for Fern Bay. I love it!

Thanks, and yes my gearing is that close in my Miata. 60 mph at about 4000 rpms 5th gear, good gas mileage on the surface streets, but not so much on the freeways, specially when I'm going 80+ mph(which is every time I go on the freeway).
Yeah, force sensing as well as force feedback in the wheel, pedals, and shifter would be nice, but probably too expensive for most players.

Maybe Tristan could comment on steering response and movement (how fast is possible) in the Reynard versus the steering wheel he uses for LFS.
Ah, it's the bi-yearly thread from JeffR and corresponding show down.

It's like the first daffodil of spring.

I have no intention of involving myself in this thread, other than to provide inane comments... Oh bugger.
Quote from the_angry_angel :Ah, it's the bi-yearly thread from JeffR and corresponding show down.

Every now and then I need to test out my flame proof suit, so I post here.

____________________
Quote from rich uk :I'm in a loving and meaningfull relationship (and have been in for over 2 years )

Animals and/or blowup dolls don't count.
Quote from JeffR :The most valuable point made here was the issue with the "magic" formula. I've always thought that interpolation of table data has always been the way to go, since tables are how real world data is sampled. I seem to recall Todd Wasson coming up with his own tire phsyics model, but don't remember if he mentioned any specifics, other that weaknesses in the "magic" formula. It's very rare that a curve fit and resulting equation with a few variables is ever going to be as accurate as a table with dozens or hundreds of sampled points.

Real world data is TAKEN in samples, but OCCURS like an equation (i.e. not discreet points). Whilst accurately taken data (of which virtually none is available in the public domain) would be best at those points, interpolation isn't necessarily accurate between them, and as soon as you go out of the measured 'zone' the whole model falls to pieces. With an equation based system (that most modern sims are heading towards anyway), if it's accurate then you get realistic behaviour in more situations. That's my take. I've yet to drive a decent feeling table based sim. Or fly one (X-Plane reference).
Quote from tristancliffe :Real world data is taken in samples, but occurs like an equation (i.e. not discreet points).

Few things in the real world occur like an equation (technically a small set of differential equations). For this discussion, one issue is hysteresis. Near the cricital slip angle, the reaction depends on the path, whether the crictial slip angle was approached from a smaller or a larger angle.

http://en.wikipedia.org/wiki/Hysteresis

The issue mentioned by GT5 developers is that the "magic" formula didn't work. Hysteresis is one of the reasons it doesn't work.

A table based approach will always work if there are enough tables and the tables are large enough, and cover all the state transitions. Considering the amount of memory available in a typical PC, there's not a significant restriction on table size. Higher order equations can be used for interpolation, resulting in a combination of table and equation based process, essentially the table is a very large set of equations.

The main issue in either case is obtaining the data. The quality of the output depends on the quality of the input (sampled data).

Most real world simulations use a combination of tables and equations. Ballistics is a classic example. The first usage of computers was to interpolate data to create tables for mortars, back during WW2.
Quote from JeffR :The issue mentioned by Forza developers is that the "magic" formula didn't work. Hysteresis is one of the reasons it doesn't work.

Fixed. As if Polyphony knows what a slip curve is.
Quote from JeffR :
I'll probably be buying a wheel and pedal set soon, maybe a G25. Recommendations welcome here. I had two issues with the Momo racing wheel and pedals. Pedal pressure was too light, especially for my clumsly left foot if I try to left foot brake (I left foot brake in my wife's car, which is an automatic, just because I wanted to learn how to do this). The other issue with the Momo wheel is the motor inertia prevents fast wheel movments, no matter how small, which is an issue when at the limits.

Before the G25 came out, I remember reading one of the Logitech guys saying that one of the problems they had with one-motor wheels is that the wheel could only be turned so fast and if it was turned any quicker it would burn the motor out. So they used FF resistance to prevent the wheel from turning too quickly.

With the two-motor FF in the G25, that is no longer a problem. I can crank the wheel back and forth as fast as I am physically able, and there is not a hint of resistance from the motors.
Quote from MRSisson :With the two-motor FF in the G25, that is no longer a problem. I can crank the wheel back and forth as fast as I am physically able, and there is not a hint of resistance from the motors.

Thanks for the info, that's what I was looking for.

A larger motor with less gearing would do the trick, the ultimate being a direct drive servo / inductive motor, although if the torque was too high, it could break the wrists of a player if the control function went bad.

Quote from Ball Bearing Turbo :
Quote :The issue mentioned by Forza developers is that the "magic" formula didn't work. Hysteresis is one of the reasons it doesn't work.

Fixed. As if Polyphony knows what a slip curve is.

I fixed my previous post. Real world physics is usually quite complicated, and the closer a simulation gets to reality, the more complex things get. For racing sims, just getting the data can be tough. Aerodynamics is fairly well known subject, but the high end programs that accurately model it are fairly expensive. Apparently some companies are releasing tire behavior data now. I'm not sure where chassis data is going to come from. All of this stuff requires extensive tables and equations to do a proper job.

I have the impression that aircraft design software (aerodynamics, frame dynamics, engine properties) has gone well beyond what is available for racing cars, probably due to the difference in budget when designing an Airbus 380 versus a Ferrari Formula 1 car.

In the case of real racing cars, simulation software hasn't reached the point that it can be trusted, so they toss a car into a wind tunnel and see what happens, gather telemetry while the cars are running on a track, and make adjustments as required. Despite all of this, design problems still occur, leading to problems like the Mercedes Lemans car that did 2 1/2 back flips with a 1/2 twist (the 1/2 twist allowing a wheels down landing was fortunate, as the driver was uninjured):

mercfly.wmv
Apparently it is very much harder to make a driving sim than a flight sim - a long but interesting watch here
Well, that's obvious. Flight Sims, with reasonably flight models, have been around for MANY YEARS. Car sims with reasonable driving models have only been around for a couple of days in comparison.
Darn someone found the video I had been searching for but yes it is much harder to simulate a car rather then an airplane for many reasons and that video does have a rather fair amount of neat/useful information if you are a nut like I am.

EDIT: Flight sims have been around for many year BECAUSE they are easier to make and are less computational, meaning in the 1980's computers could run the flight sims, where they couldn't begin to think about running a driving sim - watch that video if you haven't.
Quote from Polyracer :Apparently it is very much harder to make a driving sim than a flight sim - a long but interesting watch here

Not sure I agree.

Modeling airflow and it's effects on the aircraft in real time must be harder than trying to model tire behaviour. Every part of an aircraft's exterior shape affects the way it flies. There's no way any consumer level sim will take that into account (at least I don't think so). My experience only comes from flying RC stuff, but the subtle aerodynamic touches that you can do to tweak a plane's handling are many, and most aren't intuitive.

A car sim is largely concentrated around tire physics (yes?). Well a flight sim should be concentrated around fluid dynamics. Which is harder?

In that sense stuff like the MS Flight Sim series aren't any better than the likes of GT5. All show and no go.
Fluid dynamics adhere to formulae much better than tyres do.

The only flight sim on the market which takes into account the airflow over each part of the aircraft is X-plane, MSFS uses many canned routines and most of the air file has to be fudged to get things to fly right, most high end addons bypass the MS air files completely.

Tyre physics are a black art ATM, they just don't adhere to a certain forumla all the time, which makes it harder to simulate.
#115 - Woz
Quote from Mattesa :Not sure I agree.

Modeling airflow and it's effects on the aircraft in real time must be harder than trying to model tire behaviour. Every part of an aircraft's exterior shape affects the way it flies. There's no way any consumer level sim will take that into account (at least I don't think so). My experience only comes from flying RC stuff, but the subtle aerodynamic touches that you can do to tweak a plane's handling are many, and most aren't intuitive.

A car sim is largely concentrated around tire physics (yes?). Well a flight sim should be concentrated around fluid dynamics. Which is harder?

In that sense stuff like the MS Flight Sim series aren't any better than the likes of GT5. All show and no go.

Air is far simpler. I worked on zero hour (Means zero hour real flight time) sims over 20 years ago. The aviation industry felt they were good enough back them to drop someone into the co pilot after training then all the extra fluid dynamic stuff does not add too much more to a flight model when the planes are big enough.

BTW, these were £10,000,000+ full motion military and commercial jobs. I was mostly on the 747 and 737s.

Tyre interaction is far more subtle and to make matters worse is the most vital part of the simulation as the 4 tiny patches is what determines if it drives right or not.
Quote :G25

Looked into these, and they cost $250(USA) or more. Small aerobatic RC helicopters on the otherhand, such as the AXE CP and the Blade CP+ are selling for $200(USA) in my area so I may buy one of these. These helis are aerobatic enough to do inverted hovers. I've made my choice now where to spend my gaming / hobby money next.

Quote :flight sims versus car sims

Neither of these has to be that accurate if they are only used for basic skills. As I stated before, the software used to design aircraft (and air foils) is much more sophisticated. Aerodynamics at mach .6 or higher gets really complicated (affects commercial aircraft), and tables are used in addition to formulas as part of the algorithms used in such software, and also in the software for ballistics, which go up to mach 4.5 for bullets, higher still for missles. Fluid dyanmics is very complicated when dealing with turbulent flow, and again tables are used.
Quote from JeffR :Looked into these, and they cost $250(USA) or more. Small aerobatic RC helicopters on the otherhand, such as the AXE CP and the Blade CP+ are selling for $200(USA) in my area so I may buy one of these. These helis are aerobatic enough to do inverted hovers. I've made my choice now where to spend my gaming / hobby money next.

You get what you pay for. Here you go Jeff, here's $13,000 worth of (3) helicopters for you. Don't mess around with that small stuff.......

Quote from Jakg :Although NR2003 sells for an inflated price in the US it can be had for a fiver on eBay here.

That's an initial "low-ball" bid price, not the final bid it sold for. The buy it now price is 39.99 pounds, or almost $80(USA), so the UK prices for NR2003 are about the same as they are in the USA (otherwise I'd be buying from the UK and selling in the USA as a side business).

Quote from mrodgers :You get what you pay for. Here you go Jeff, here's $13,000 worth of (3) helicopters for you. Don't mess around with that small stuff.

Must be similar to the Raptor 90 with all upgrades, similar to the one used in this video (the action starts about 25 seconds into the video).

rcheli.wmv

Those type of helis are out of my league. If I go beyond the Blade CP+, the next one will be a Blade 400, $480(USA). Considering how often the experts crash those things, it's an expensive hobby. For now, all my rc heli stunts will remain in the RealFlight rc simulator.
OK, I'm new to LFS and as many people in this thread have asked for people with single-axis-pedals to stand up and be counted, well, here I am... I for one would like to think that having a cheapo steering wheel holds me at no distict disadvantage to those with super leather-stitched ones. On the flipside, I definitely don't want to be at an advantage to drivers who use more realistic controllers and would certainly expect them to achieve better times, but not to the extent that other drivers fall by the wayside. I think it's up to the developers to find a balance, which regrettably takes time and resource.

Speaking of developers, I noticed a few (dare I say elitist?) posters consider the total realism of this sim to be the topmost priority even if it loses paying punters. If I was the developers I would be concerned with limiting my market in this way, and I think the elitists should be too - after all, if the coppers don't keep rolling in then there is unlikely to be any further development! IMO, these few concessions could help keep the money coming in and make a better product for everyone.

Maybe I'll buy a G25 in the future (and probably change my opinion!) but at the moment I have better things for my wife to spend my money on.
The developers aren't doing it for the money and thats one of the main things that got me interested in the paying for it was that it was one of the closest things I can get without buying a $3000 car and $100 track days to mess around at the limits. I don't think they will care to keep it as real as possible as thats (AFAIK) the direction they want to go in the first place.

As far as single axis controllers I don't know what to say, you can find all the information in this thread, and they are very old although a few are still kicking around here and there. They are by far better then keyboard and mouse, but its the slightest disadvantage in some cars. It will be more noticable as the overall driving speed and acceleration of the cars increases: IE the GTRs and SS's will be more noticable if you don't blip the throttle then say the UF1, XFG and XRG which are all lower powered and you won't lockup the wheels from not blipping (as badly anyway, drop 2 or 3 gears and it can still happen)
Quote from blackbird04217 :The developers aren't doing it for the money

Even if money is not their primary goal (which I agree it most likely isn't), money is still an important factor in the development of a product like this. If it wasn't, LFS would be free. I suspect their phasing of releases is a deliberate move to ensure revenue is continually available to support development - a model I completely buy into and one of the reasons I was drawn to LFS in the first place. My point is, without this funding there is a strong chance the development would cease, which is bad for everyone.

Quote :As far as single axis controllers I don't know what to say, you can find all the information in this thread, and they are very old although a few are still kicking around here and there. They are by far better then keyboard and mouse, but its the slightest disadvantage in some cars. It will be more noticable as the overall driving speed and acceleration of the cars increases: IE the GTRs and SS's will be more noticable if you don't blip the throttle then say the UF1, XFG and XRG which are all lower powered and you won't lockup the wheels from not blipping (as badly anyway, drop 2 or 3 gears and it can still happen)

Thanks for the advice - I'm OK with this (I think) as long as the races don't become unplayable or uncompetitive due to the hardware limitation, which is what JeffR appeared to be suggesting in the original post - maybe I misinterpreted.
Quote from buggle52 :Even if money is not their primary goal (which I agree it most likely isn't), money is still an important factor in the development of a product like this. If it wasn't, LFS would be free. I suspect their phasing of releases is a deliberate move to ensure revenue is continually available to support development - a model I completely buy into and one of the reasons I was drawn to LFS in the first place. My point is, without this funding there is a strong chance the development would cease, which is bad for everyone.

I didn't say money isn't important. It is important because it allows the developers to continue on LFS without getting other jobs. But I think they will receive enough support from those die hard realism fans, otherwise they probably would have waited a bit longer before releasing some of the improvements such as clutch heat, stalling and removing the helpers... But yes- it is important that we continue to support them and their decisions.

assists and realism in LFS
(122 posts, started )
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