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crankyoldmanSo I got my tire model to work. And I figured that in the spirit of actually understanding what's going on, I'd share the fuckyeahawesome that is my tire model.
Now what the hell do I mean by 'tire model'? Well, when you're trying to figure out the handling on a vehicle (how it turns and reacts to turning input) you need to know how the tires will react to shit. And unless you're in fairy land, they're going to slip a little.
If you've got a car, think about doing donuts in the parking lot. Or just turning really fast. There's a bit of skid, eh? Moreso if you're bike dependent like me (though I find the skids fun unless I'm going to be run over). Friction is crazy stuff!
Since simulations are just a fancy dancey way of saying, "taking equations and seeing if they hold up to the real world" my tire model is basically some equations that tell you how much lateral force is being put on each tire.
What's lateral force?
That. You are traveling in one direction, and there's a force being applied perpendicular to you. It's like you're running down a hall with someone running beside you pushing at your side (or pulling). Like that.
Why does lateral force matter? Well, that's where the slipping happens when you turn a car! As a passenger in one you feel it; you're sitting on the left side of a bus, it makes a right turn and you get pushed into the window a little, right? The lateral force of the tire to the ground keeps the vehicle making that turn like the window keeps you from flying out of the bus.
Anyway, so two major factors (variables) go into the model; slip angle and the weight on the tire. The slip angle is just a nifty geometric variable for the angle between where the tire is pointing and where the vehicle is going, in reference to the tire's slight mooshing.
Like so. Cause tires moosh! They aren't perfect!
The next is the weight. For this particular model, the weight is constant for a range of slip angles. This is a good thing. It's much more complicated if the weight changes (and probably means the kids are jumping around in the car! STOP IT. XD). But we still want to know what it'll do for different weights, cause that's useful.
The really neat thing is this effect isn't constant, but it does have a nifty graphical relationship.
Whoa ho ho, isn't that NEAT LOOKING? Anyway, how to read that! Each line is one constant weight on a tire. The slip angle and lateral force change for that weight, naturally. So if you pick a point on any of the lines, you'll have the lateral force at that slip angle and weight! COOL HUH?
...I'm way too excited about this. XD
Edit: Graph translation: if the slip angle is big (i.e. you're sliding a little to the side), it takes more force to keep it in a turn. The factor of the force is also dependent on how heavy of a vehicle you have; this is why large vehicles make wider turns!
Now what the hell do I mean by 'tire model'? Well, when you're trying to figure out the handling on a vehicle (how it turns and reacts to turning input) you need to know how the tires will react to shit. And unless you're in fairy land, they're going to slip a little.
If you've got a car, think about doing donuts in the parking lot. Or just turning really fast. There's a bit of skid, eh? Moreso if you're bike dependent like me (though I find the skids fun unless I'm going to be run over). Friction is crazy stuff!
Since simulations are just a fancy dancey way of saying, "taking equations and seeing if they hold up to the real world" my tire model is basically some equations that tell you how much lateral force is being put on each tire.
What's lateral force?
That. You are traveling in one direction, and there's a force being applied perpendicular to you. It's like you're running down a hall with someone running beside you pushing at your side (or pulling). Like that.
Why does lateral force matter? Well, that's where the slipping happens when you turn a car! As a passenger in one you feel it; you're sitting on the left side of a bus, it makes a right turn and you get pushed into the window a little, right? The lateral force of the tire to the ground keeps the vehicle making that turn like the window keeps you from flying out of the bus.
Anyway, so two major factors (variables) go into the model; slip angle and the weight on the tire. The slip angle is just a nifty geometric variable for the angle between where the tire is pointing and where the vehicle is going, in reference to the tire's slight mooshing.
Like so. Cause tires moosh! They aren't perfect!
The next is the weight. For this particular model, the weight is constant for a range of slip angles. This is a good thing. It's much more complicated if the weight changes (and probably means the kids are jumping around in the car! STOP IT. XD). But we still want to know what it'll do for different weights, cause that's useful.
The really neat thing is this effect isn't constant, but it does have a nifty graphical relationship.
Whoa ho ho, isn't that NEAT LOOKING? Anyway, how to read that! Each line is one constant weight on a tire. The slip angle and lateral force change for that weight, naturally. So if you pick a point on any of the lines, you'll have the lateral force at that slip angle and weight! COOL HUH?
...I'm way too excited about this. XD
Edit: Graph translation: if the slip angle is big (i.e. you're sliding a little to the side), it takes more force to keep it in a turn. The factor of the force is also dependent on how heavy of a vehicle you have; this is why large vehicles make wider turns!