Algobox - Realistic Tires (ABS works on these)

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Realistic Tires (ABS works on these)

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Author: The Linkage

Group: Technical

Filesize: 18.76 kB

Date added: 2017-03-15

Rating: 5.6

Downloads: 1366

Comments: 4

Ratings: 2

Times favored: 0

Made with: Algodoo v2.1.0

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The main thing I disliked about Algodoo's cars for some time was the absence of dynamic friction. A.K.A if your car's wheel was NOT slipping and at the verge of locking vs if it was locked will yield the same braking distance, and acceleration. This is obviously not like that irl. so I became obsessed with dynamic friction and finally decided it was time to do this thing. I thought it would be hell to make... but it took 5 minutes

go figure

Basically calculates speed based on angVel like a real car, then uses the real vel to compare, and if the |difference| between the two is higher than 1, then the wheel gets a big decrease on friction - from 1 to 0.5 (changeable ofc)

To do the test HOLD the keys (nothing bad will happen if you don't anyways!)
W to accelerate, S to brake

Use the grid as a speed reference

Last edited at 2017/03/19 14:24:06 by The Linkage

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WyattTheMarbleRacer

2017/03/15 23:41:41

Pretty Cool

s_noonan

2017/03/16 23:19:18

Nice work. I changed the code to:

vCalc := _abs(radius * angVel);
vAbs := math.vec.len(vel);
vAbs > 0.01 ? {
r := vCalc / vAbs;
r < 0.99 || r > 1.01 ? {
_dyna = true;
friction = 0.5;
color = [1, 0.3, 0.3, 1]
} : {
_dyna = false;
friction = 1;
color = [0.3, 0.3, 0.3, 1]
}
} : {
_dyna = false;
friction = 1;
color = [0.3, 0.3, 0.3, 1]
}

This code takes into account hills by calculating the total velocity. It defaults to no slipping below 0.01 m/s, otherwise tires go red on 1% slippage.

Last edited at 2017/03/16 23:26:34 by s_noonan

The Linkage

2017/03/17 00:28:50

I didn't want to do that because the wheels would lose traction if they go up suddenly (like a bump on the road: the velocity would be added but the wheel's velocity would be the same) or if they are in the air (but this probably would make them slip if you keep accelerating in the air anyways). But I think I'll do some tests anyways

s_noonan

2017/03/17 22:45:37

I agree with your observation that a step velocity change will be perceived as slippage.

Other than that, both of our approaches are similar. My limits are based off of the velocity ratio while yours are based off of velocity difference. At any rate, I like your use of "math.toInt(vCalc - vAbs) == 0". That is a concise way of setting bidirectional limits without having to worry about either velocity being close to, or equal to, zero. As you probably know, you could scale that line of code like "math.toInt(10.0 * (vCalc - vAbs)) == 0" to set tighter limits.