The implamentation of "flat-spots" into the game engine

First thing first, this is not a justification why flat spot simulation should be in beamng.drive but rather an in-depth discussion on the implementing the mechanic into the game. Everyone already knows this feature is desired amongst the community.


Basic layout

1. A brief explanation of “Flat-Spots”

2. How does the game simulate tyres

3. What does the “Flat-Spot” simulation need to achieve

4. How can it be achieved


Flat spots

For those who do not know, flat spots appear after locking the breaks for any reason on tarmac. Locking the breaks causes a large amount of rubber to be worn out on one small area on the tyre causing it to become unbalanced. At speeds this rattles the suspension and lowers grip on effect tyres under breaking which can make it even worse.





Current tyre model

This is a model of a tyre jbeam I made on desmos



The lines on the picture represent beams and the dots are nodes. The green beams make up the rim and should not move. The orange beams simulate both the tyre wall and the internal pressures. They are set to a certain length and can be compressed and apply an extending force relative to pressure in the tyre. Importantly they can not be extended longer than the set length or the tyre will burst. They also control the thickness of the tyre profile. The purple beams are the same as the orange beams but they simulate the tread. The outer nodes are what contact the ground. Importantly they have two important values mass and grip.

Where is a picture showing the different forces between the beams. (red is compressional and blue is torsional)





Requirements for mechanic

For the mechanic to work it needs to for fill the following requirements

1. Tyre disbalancement

2. Tyre bump

3. Loss of grip



Implementation

The important part is that all the factors are accounted for. So firstly different tyre compounds will ware out at different rates. Also contact area needs to be accounted for. Because different tyres have different treads of different widths it is easy just to rap it all up into one value that includes all tyre related properties which the tyre coefficient or Co will be. Next the further the skid goes for the more rubber will come off so it will be expressed as d for distance. Lastly the more load the tyre is under the more also will come off which will be expressed as F.

Since the outer nodes have a mass, the mass can be reduced to create the disbalance. The formula doesn’t need to be practically complicated just where M = the total mass of the node and M0 is the initial mass of the node (M=M0-CoFd). A very simular equation could be used for the for the bump of the tyre just using a different coefficient. The adjustment would be easy, just lower the set length of the orange beams. also the grip can be adjusted using a curve biased on the changing compounds through the tyre.

sorry I needed to rush at the end there, it's like 5am for me and knowing myself, if I don't finish it now it probably won't ever be finished. anyway let me know what you think, I don't know why I did this to myself.

 

reducing the mass of the nodes seems like quite an elegant solution, come to think of it. of course, they would probably need to modify the core physics engine to allow for the active alteration of node weights, but it would open opportunities for other things, like changing the mass of a fuel tank as it drains.

 

That is already implemented. Your car will get slightly lighter as your fuel tank drains. If they are going to do flat spot simulation, I imagine they would wait until tire thermals are finished.

 

I imagine the biggest difficulty of the mechanic would be finding who far the node traveled while sliding, this is not something that is supported by the game engine yet. The only way I think it could be done is by measuring the speed of the node as it is in contact with the ground and then dividing the average by the time of the slide. Maybe an interval. The problem is that there may be a slight performance impact of the system.

 

@estama You know whats what with these things always a good reliable source but I suspect the entire flat spot argument is going to be added sometime but cannot confirm anything yet

 

Speaking of tire wear/thermals, is that being given attention yet or is it simply "on the list" still?