# A simple physics model for vehicles on different surfaces?

1. Jul 16, 2015

### electrodruid

Hi,
Just to let you know my level of knowledge/ability, I studied a degree that included some dynamics, but that was nearly 15 years ago, so I'm rusty. I'm a games programmer, and I tend to understand code (or things that can be translated into code) more easily than hardcore maths equations, but I'll take any help I can get.

So, I'm trying to figure out how to build a way to simulate different vehicles moving along different kinds of tracks. The simulation will be non-interactive, so it's not like a standard driving game where the player controls the acceleration, etc. So, to begin with, let's imagine two cars doing a straight drag race on tarmac.

What I want is to be able to input some basic stats about each car (I guess stuff like horsepower, weight, torque, etc. - but I'm open to suggestions about what will best fit the model). The output should be some kind of curve or function which describes the car's movement along the track: a car that accelerates quickly but has a limit on its top speed might lose against a car with a slower acceleration provided that the track is long enough to allow it to overtake, for example. What's the simplest way you can think of for generating this kind of output from a given set of inputs?

Ultimately I also want to factor in environmental stuff like the surface type, weather etc: Given two otherwise identical cars on a wet road surface, the one with the slick tyres will beat the one with normal weather tyres. Four wheel drive vehicles will do better than 2 wheel drive on a hilly dirt track. A powerful drag racer will beat almost anything on tarmac but will likely run into problems on dirt/sand.

For bonus points, consider tracks with corners. Again, I'm not looking for a completely realistic model, but perhaps something that takes into account that a vehicle with higher mass will presumably need to decelerate more to take sharp corners than a lighter vehicle.

Um, so this sounds like a lot - sorry! At this point I'm just looking for some pointers - suggestions as to suitable input parameters, and suitable ways to have those interact to produce a distance over time curve that will probably not be particularly physically accurate but will be a suitable "quick and dirty" way of showing how well a car with a given set of characteristics will perform on a given track. Any suggestions?

2. Jul 16, 2015

### Dr. Courtney

The key issue is the coefficient of friction under different surface conditions.

3. Jul 19, 2015

### abdullahi abass

Its a lot. I'll advice you to start with a model that has some basic functions then add more and more until it gets to your desired complexity. Say, you can start by defining the car's mass(M), force of the engine(F), frictional force(Fr), length of track, the rate at which air resistance increases with speed(ß)[in order to determine the maximum velocity ]. I'll try to work? on a function with these variables that would define the car's motion.

4. Jul 25, 2015

### Shreyas Samudra

how know everything !
only thing i would like to suggest is carefully incorporate the torque factor, because sometimes having incorporated it excessively controlling car becomes very difficult , turning becomes very problematic as in GTA IV