View Full Version : AWD system in Shift 2
jury1111111111
5 April 11, 19:20
Hello everybody! :)
So far I'm not a proud owner of the new Shift 2, so I want to ask you lot a question: How does the all-wheel-drive system work in shift2? Is the torque bias locked to 50:50 like in shift1, or is it dependant on the car (like 80:20 for Lamborghini Gallardo), or is it even adjustable?
Thanks in advance for your response,
cheers!
No change whatsoever, it's exactly the same as Shift - 50:50 - take it or leave it. Guess they couldn't be bothered.
There's a thingy called Visco Electronic Lock.
The descriptions says that if you slide the bar to one side you will get more power and to the other side you will get more maneuverability or something.
Now i have no idea what the hell that means and i bet the one who made it like that didn't have any idea of what he was doing.
This should be something like a centre differential with adjustable torque bias.Or something like that.
So yeah i think the torque bias is fixed again.
It's exactly the same as Shift. The so called Pump setting, also called Visco Electronic Lock in the game, was used both on 4WD cars as well as some of the Ferraris to simulate the E-Diff (an maybe some other cars as well, not sure whether intentionally or just by mistake). The regular Power/Coast/Preload settings are commented in the chassis files saying these settings are not implemented for 4WD, meanin the Pump setting is the only differential setting which affects a 4WD car. As to how exactly it affects a 4WD car's torque distribution is unclear though, as it only takes a torque threshold as input, there's no other setting that would say how much torque is being redirected to which end of the car or what the static, dynamic, min, or max torque distribution values would be.
It's exactly the same as Shift. The so called Pump setting, also called Visco Electronic Lock in the game, was used both on 4WD cars as well as some of the Ferraris to simulate the E-Diff (an maybe some other cars as well, not sure whether intentionally or just by mistake).
right :thumbup:
lock it on the GT-R to 100% and you can do donuts and it's more stable in corners. 0% drives like a lancer without viscous or maybe snow mode on newer models...
The regular Power/Coast/Preload settings are commented in the chassis files saying these settings are not implemented for 4WD, meanin the Pump setting is the only differential setting which affects a 4WD car. As to how exactly it affects a 4WD car's torque distribution is unclear though, as it only takes a torque threshold as input, there's no other setting that would say how much torque is being redirected to which end of the car or what the static, dynamic, min, or max torque distribution values would be.
- the comments like // or ; are usually skipped to the next line by any program
so there's no influence on physics whatever you write
- your right there no way to display the differential mapping
according to the file 300 value read as nM maximum would equal around 30-70 maximum torque distribution on the GT-R. or depending on the mapping 70-30.
jury1111111111
6 April 11, 16:26
Thank you very much for your responses!
So if I understand you well, you tell me that the torque distribution is adjustable via the Visco Electronic Lock, but how it really affects the bias is unclear, right?
Shame that Shift 2 can't simulate proper torque distribution like rFactor (there it wa even adjustable!)... Even in Shift 1 I was looking forward to drifting the Audi R8 or the Lambo Gallardo, which we all know are quite good dancers on the track, but.... :( It wasn't really possible. The only way I could drift the 4x4 cars was to set a very high tire pressure at the rear + some adjustments meant to provide the rear of the car with less traction. It worked for drifting, but then the cars didn't have enough grip...
just BTW, could you lot find out how the visco electronic lock affects the car via the telemetry system? Maybe you will be able to compare tyre loads during hard acceleration in low gears... I wonder what the result will be :)
- the comments like // or ; are usually skipped to the next line by any program
so there's no influence on physics whatever you write
- your right there no way to display the differential mapping.
you must have gotten something wrong about what I said. I didn't say the settings themselves were commented out, I was referring to the fact that the comment next to them explicitely states (not implemented for four-wheel drive)which means the physics engine does not use those settings in case of a 4WD car, leaving the pump setting the only one affecting a 4WD car. It is unclear though as to how it is used for a 4WD, i.e. is it being used as a center diff, or as front/center/rear since no other diff settings are being used, according to the text in the comment
according to the file 300 value read as nM maximum would equal around 30-70 maximum torque distribution on the GT-R. or depending on the mapping 70-30.
Again, there's a comment saying at 100% pump diff setting, the torque redirected per wheelspeed difference in radians/sec (roughly 1.2kph) - since it mentions wheelspeed difference it doesn't sound like it's referring to a center diff, but who knows, maybe it works as such if WheelDrive=FOUR (=input/output shaft difference in angular velocity) and as a standard axle diff (=wheelspeed difference in angular velocity) if it's not a 4WD car. Anyway, the 4WD system looks like some hack rather than a fully thought out implementation, I just don't see a possibility to reproduce a modern 4WD car's handling this way. It would require different settings for all three differentials, including different gear ratios for front and rear axle differentials and a lot of settings for the center differential to specify static, dynamic, and min/max torque distribution limits.
you must have gotten something wrong about what I said. I didn't say the settings themselves were commented out, I was referring to the fact that the comment next to them explicitely states (not implemented for four-wheel drive)which means the physics engine does not use those settings in case of a 4WD car, leaving the pump setting the only one affecting a 4WD car. It is unclear though as to how it is used for a 4WD, i.e. is it being used as a center diff, or as front/center/rear since no other diff settings are being used, according to the text in the comment
and i said if something explicitely states something in the comments it gets ignored by the program anyway.
Again, there's a comment saying at 100% pump diff setting, the torque redirected per wheelspeed difference in radians/sec (roughly 1.2kph) - since it mentions wheelspeed difference it doesn't sound like it's referring to a center diff, but who knows, maybe it works as such if WheelDrive=FOUR (=input/output shaft difference in angular velocity) and as a standard axle diff (=wheelspeed difference in angular velocity) if it's not a 4WD car.
- see above
- there's no 'physical' difference between center or global differential. you don't place a differential in the center of the car and then make it act. similar to engine for example, in the end its placement is only globally set in weight (and inertia)
- yeah differential only works on powered wheels (although TC, ABS and so on sometime work in a similar way affecting all wheels on RWD cars)
Anyway, the 4WD system looks like some hack rather than a fully thought out implementation, I just don't see a possibility to reproduce a modern 4WD car's handling this way. It would require different settings for all three differentials, including different gear ratios for front and rear axle differentials and a lot of settings for the center differential to specify static, dynamic, and min/max torque distribution limits.
- viscous and speed is the heart of a differential, basically your not doing more in some modern AWD road cars then adjusting the viscous / speed setting while the general mapping is fixed
which in tuning -> test almost works on-the-fly (just have to enter the set-up menu)
- yep
TUNDRA_schumacher
7 April 11, 02:20
Out of all the AWD's (that's what they are.....4WD is for trucks) I like the Lancia the best, and the Audi TT 2nd. My wife owns an AWD and they both drive and handle a lot like her car does.
Hagane007
7 April 11, 03:16
Only the AWD vehicles are drive-able for me... Unless I throttle really softly with RWDs...
the AWD cars in the game are good at default. but once u start moding them they become this super cars that can brake the laws of physics. its ridiculous. the lamborghini fully modded is the fastest car in the game up to now from what ive seen you can just drive like a maniac and still have control over it. i dont like them AWD car behavior on the game
Out of all the AWD's (that's what they are.....4WD is for trucks) I
You sir just gave me a really good laugh... Can I quote you and put that on a t-shirt?
Please tell me how you define the difference between AWD and 4WD as long as the vehicle in question only has 4 wheels total? Also, I guess the game simulates "trucks" then, because the setting in the chassis file is called WheelDrive=FOUR? Which is what the setting is called in rFactor as well? You know, rFactor, the game famous for simulating the largest variety of trucks ever? (hint: irony)
You do know there are trucks with 6 and even 8 wheel drive (3 and 4 driven axles respectively), don't you? So you'd call those 4WD too, because... they are "trucks", right? FYI: I know there's a language problem here because americans generally call all pickups, suvs and offroad vehicles "trucks", but still, I'd be more then curious to learn how you differentiate between AWD and 4WD in case of a vehicle with no more than 4 wheels, whether the vehicle is something you call a "truck" or not?
4WD have locked front/rear bias which makes a lot of drag on turning/high speed.. AWD uses viscous coupling or electronic distribution such as haldex which uses clutches to enable the other set of wheels with a variable bias thus reducing drag.
at least this is what I believe
as for the game, I dont think they wouldve implemented the sort of electronic distribution modern cars have, I dont think they even take into account the drivetrain drag force of a 4WD when turning, making the 4WD feel like AWD
my guess, and from my phys-x SDK experience, they are just setting rotational torque of each wheel and not relying on any feedback to alter the torque on the other wheels, this would be the simplest method and would reproduce the 4-wheel drift these cars are known for... who would be the wiser?
Only the AWD vehicles are drive-able for me... Unless I throttle really softly with RWDs...
Well, yes, that's exactly what you should do with a powerful RWD vehicle. If you're not using TC and SC already, enable those to get used to RWD, maybe also reduce acceleration sensitivity to avoid spinning out under acceleration. As you learn to control RWD cars you'll see how fun it is to drive one, and how rewarding it is to master one.
the AWD cars in the game are good at default. but once u start moding them they become this super cars that can brake the laws of physics. its ridiculous. the lamborghini fully modded is the fastest car in the game up to now from what ive seen you can just drive like a maniac and still have control over it. i dont like them AWD car behavior on the game
That's exactly the problem. They are too good. Because of that they get pretty boring after a short time, there's just no satisfaction in driving one - just hop into any one at any time and drive it like a maniac right away... boring. Problem number 2 is they understeer and don't reflect the behaviour of their real-life counterparts.
4WD have locked front/rear bias which makes a lot of drag on turning/high speed.. AWD uses viscous coupling or electronic distribution such as haldex which uses clutches to enable the other set of wheels.
No, you cannot say that in general.
Older "AWD" cars (80's and 90's) also had/have locked torque bias.
And not everything that says "AWD" or "4WD" or whatever we call it, has a viscous coupling at the center, one of the most famous systems is Audi's quattro which uses a mechanical Torsen center diff. The smaller Volkswagen group cars with transversely mounted engines do indeed use the Haldex clutch, but those are not always-on AWD either, usually only the front axle is driven with the rear being connected only when deemed necessary.
Personally I don't care whether people call it AWD or 4WD, but the claim "they're AWD, because 4WD is for trucks" was just hilarious at that point. :D
as for the game, I dont think they wouldve implemented the sort of electronic distribution modern cars have, I dont think they even take into account the drivetrain drag force of a 4WD when turning, making the 4WD feel like AWD
my guess, and from my phys-x SDK experience, they are just setting rotational torque of each wheel and not relying on any feedback to alter the torque on the other wheels, this would be the simplest method and would reproduce the 4-wheel drift these cars are known for... who would be the wiser?
Well that's my point - the implementation, as it appears from the settings available in the chassis file, is overly simple and therefore cannot simulate a modern AWD/4WD street- or sportscar with enough accuracy to make it feel in-game as it does in real life - as opposed to FWD/RWD cars for which there is a reasonable amount of settings to simulate that one differential these cars have. That the actual data used hardly has anything to do with the real car's characteristics is another matter altogether, at least getting power and coast settings right is easy even for someone just searching the internet for a couple of hours, for a developer claiming to have excellent connections to the car manufacturers it should be an non-issue (I'm still talking about FWD/RWD cars here, so I'm getting a bit off-topic, sorry for that)
But correct data is not what Shift is known for, unfortunately. To be fair though, there is a lot of generic data in other ISI-based games and mods as well, and still those are being celebrated to this day as being the pinnacle of accurate car simulation.
TUNDRA_schumacher
7 April 11, 13:16
Generally, the terms 4WD( Four-Wheel Drive) and AWD ( All Wheel Drive) both describe vehicles in which engine power is transmitted to all four wheels, unlike normal vehicles in which only two wheels receive torque from the engine.
Although 4WD and AWD sounds similar, there are some functional and design differences between both systems. The term 4WD describes a drive system in which the engine’s power can be switched between two speed ranges and transmitted to all four wheels. AWD drive system lacks the two speed transfer feature. By having this feature 4WD is considered superior to AWD.
Another key difference found between today’s AWD and 4WD vehicles is, how engine power is shared between front and rear wheels. Under normal driving, AWD vehicles deliver 90 percent of its engine power to the front wheels. Additional engine power is diverted to rear wheels via viscous coupling, only when the front wheels start to slip. On the other hand, usually a 4WD transmits almost all of its engine power to the rear wheels. The second speed option available in 4WD allows to split the engine power equally between front and rear wheels
:-P
the AWD cars in the game are good at default. but once u start moding them they become this super cars that can brake the laws of physics. its ridiculous. the lamborghini fully modded is the fastest car in the game up to now from what ive seen you can just drive like a maniac and still have control over it. i dont like them AWD car behavior on the game
uhm AWD dominated all racing series were they were allowed (some 20 years ago for GT racing and so on)? still are fast track cars. not to mention rally.
really you don't got a point there. and imagine how much AWD systems improved compared to 20 years ago.
still of course people are obsessed for RWD sports and racing cars for good reasons i agree so far :thumbup:
4WD have locked front/rear bias which makes a lot of drag on turning/high speed.. AWD uses viscous coupling or electronic distribution such as haldex which uses clutches to enable the other set of wheels with a variable bias thus reducing drag.
at least this is what I believe
as for the game, I dont think they wouldve implemented the sort of electronic distribution modern cars have, I dont think they even take into account the drivetrain drag force of a 4WD when turning, making the 4WD feel like AWD
my guess, and from my phys-x SDK experience, they are just setting rotational torque of each wheel and not relying on any feedback to alter the torque on the other wheels, this would be the simplest method and would reproduce the 4-wheel drift these cars are known for... who would be the wiser?
- 1. is exactly what viscous e-lock does ingame. you just can't map it in set-up. of course you don't use clutches you can only try to simulate the same lock in different driving situations.
- nothing except collision utilizes physx
@jury1111111111: i dunno what to look at in telemetry, load and camber thrust doesn't seem that greatly affected, compared to for example driving in an oval track where you easily can spot the track camber affecting the car. it's similar to Live for Speed where you can map fixed torque bias plus some viscous amount (20nM / rad max on the RB4)
Generally, the terms 4WD( Four-Wheel Drive) and AWD ( All Wheel Drive) both describe vehicles in which engine power is transmitted to all four wheels, unlike normal vehicles in which only two wheels receive torque from the engine.
Although 4WD and AWD sounds similar, there are some functional and design differences between both systems. The term 4WD describes a drive system in which the engine’s power can be switched between two speed ranges and transmitted to all four wheels. AWD drive system lacks the two speed transfer feature. By having this feature 4WD is considered superior to AWD.
I've never heard of anything like this, so I checked with good old Wiki P. before replying here - and it says Manufacturers often use these terms interchangeably, and the English word all is obviously equivalent to the word four when referring to a set of four wheels - which is what I said before even reading that. There also another interesting thing, pointed out in a nice box with a border and icon and all: The examples and perspective in this article deal primarily with North America and do not represent a worldwide view of the subject. Please improve this article and discuss the issue on the talk page. (December 2010) - so let's close this due to regional and language differences... but I'm still curious as to how you would describe a truck or other type of offroad vehicle with 3 or 4 driven axles ;)
And your description of 4WD is not superior to AWD in general, it can be superior to AWD in heavy off-road conditions, which isn't exactly what Shift is aimed at.
Another key difference found between today’s AWD and 4WD vehicles is, how engine power is shared between front and rear wheels. Under normal driving, AWD vehicles deliver 90 percent of its engine power to the front wheels. Additional engine power is diverted to rear wheels via viscous coupling, only when the front wheels start to slip. On the other hand, usually a 4WD transmits almost all of its engine power to the rear wheels. The second speed option available in 4WD allows to split the engine power equally between front and rear wheels
:-P
Ok, this just blew my mind. I'm sorry man, but this is as wrong as it gets. Where in the world did you pick this up? Please cite at least one source! How did you ever conclude that an "AWD" delivers power to the front wheels primarily? So Audi R8s, Porsche Turbos and Carrera 4s, Lamborghinis and Bentley Continentals, to name but a few, are 90% FWD cars or what? All these cars default to around 80% rear torque distribution with both axles permanently driven (ok, the Continental only has a 60% rear bias). What you're talking about is a limited (and relatively new) case of "AWD" - the clutch type "AWD" (Haldex Traction is a widely known manufacturer of such systems) but this neither a typical, nor a true AWD or 4WD system, and also these types of systems are used only on slower cars, small SUVs or crossovers, not (high) performance cars (the Audi A3 and TT are two such cars also found in Shift - not that the game would actually simulate this type of clutch for them).
What you said does not apply to either viscous or mechanical type differential AWD cars where both the static and dynamic torque distribution is determined by the differential, not by the fact that it's an "AWD" or "4WD" according to what you called them. "4WD" according to your description refers to an off-road vehicle ("truck"), which doesn't need rear wheel drive, it needs both axles to be driven since it needs to navigate difficult terrain where anything is possible. As for how that differential is set up, that's determined by the vehicle's intended purpose (extreme off-road vehicle, high-performance road car, rally car for a mix of off-road and on-road, etc.)
Also the second "speed" you mention doesn't have to do with torque distribution, but with gear reduction, so the vehicle can move very slowly in extreme terrain but still access the torque provided in the engine's higher rev range. Otherwise it would either be starved of torque at low speeds, or it would have to move at high speeds to be able to use the torque, but high speeds are usually not possible in difficult off-road environments.
TUNDRA_schumacher
7 April 11, 20:38
I just posted the first thing I found on google just to screw with you guys
http://www.differencebetween.net/technology/difference-between-awd-and-4wd/
http://forum.falloutstudios.net/style_emoticons/cncre/GoogleSmiley.gif
http://www.youtube.com/watch?v=BBhSsl1wU4U
I did understand that in american english 4WD mainly refers to offroad vehicles, and I can understand now why you said 4WD was for trucks. I also understand now why you insist on a 4WD having a reduction gear, it's because off road vehicles do have one, but I hope you do realize that it's neither required or otherwise linked to 4WD drivetrain technology, nor is it useful in any form for street, sport or racecars. Obviously "4WD" and "trucks" does not necessarily mean the same thing all around the world, even though it's in english, and I don't share your view, but I'm ok with it and can understand it.
But the rest of your post is way off. I see now where you got it (copied it ;)) from... well, forget it, it's bullshit, I'm sorry. Find one person on this forum who shares the same views. If you really care about facts, think a little bit for yourself instead of just copying stuff from the first result google spits out. I could go on and on about various cars starting with the 70's into the present day sportcars and supercars I already mentioned proving those claims wrong. And I'm neither a drivetrain engineer, nor particularly interested in AWD/4WD, I just like cars in general and like to understand how things work, rather then pick a google result and post it in a forum as if it were my own view with regard that matter.
I don't mean to be subjective, but all websites called "what is that" and "what's it about", "how does it work", "answers to everything" and such are pretty much useless because they are only meant to attract visitors and generate revenue through the ads posted on the site, since most people search for information using exactly those expressions and are lured to the respective sites. The information posted on those sites is superficial, unverified, and often plain wrong or outdated. I never even consider such sites when searching for technical information. There's plenty of sites and forums specialized in various aspects of automotive technology with people having the experience and skills to point out how something works and provide trustworthy sources of information for backing up their claims. Hell, wikipedia is a million times better, even though you shouldn't bet your house on what it says either, but it's a good starting point in most cases and also provides references to more specialized sources of information.
TUNDRA_schumacher
8 April 11, 12:05
I did understand that in american english 4WD mainly refers to offroad vehicles, and I can understand now why you said 4WD was for trucks. I also understand now why you insist on a 4WD having a reduction gear, it's because off road vehicles do have one, but I hope you do realize that it's neither required or otherwise linked to 4WD drivetrain technology, nor is it useful in any form for street, sport or racecars. Obviously "4WD" and "trucks" does not necessarily mean the same thing all around the world, even though it's in english, and I don't share your view, but I'm ok with it and can understand it.
But the rest of your post is way off. I see now where you got it (copied it ;)) from... well, forget it, it's bullshit, I'm sorry. Find one person on this forum who shares the same views. If you really care about facts, think a little bit for yourself instead of just copying stuff from the first result google spits out. I could go on and on about various cars starting with the 70's into the present day sportcars and supercars I already mentioned proving those claims wrong. And I'm neither a drivetrain engineer, nor particularly interested in AWD/4WD, I just like cars in general and like to understand how things work, rather then pick a google result and post it in a forum as if it were my own view with regard that matter.
I don't mean to be subjective, but all websites called "what is that" and "what's it about", "how does it work", "answers to everything" and such are pretty much useless because they are only meant to attract visitors and generate revenue through the ads posted on the site, since most people search for information using exactly those expressions and are lured to the respective sites. The information posted on those sites is superficial, unverified, and often plain wrong or outdated. I never even consider such sites when searching for technical information. There's plenty of sites and forums specialized in various aspects of automotive technology with people having the experience and skills to point out how something works and provide trustworthy sources of information for backing up their claims. Hell, wikipedia is a million times better, even though you shouldn't bet your house on what it says either, but it's a good starting point in most cases and also provides references to more specialized sources of information.
I did say I just posted the first thing I found to make yer head explode........and it obviously worked :mrgreen:
for me naming isn't really imported. where's a difference between all wheels and 4 wheels powered on a 4 wheeled vehicle. i don't get it... :der:
of course the military thing 2x4, 4x4, 4x6 and so on still makes sense as one value describes the powered wheels, and the other the wheels in total.
let's get back to topic :thumbup:
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