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suspension of a car

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What sort of movment does the car suspension allow to the wheels?

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Well, if you're looking for an equation, you can simulate it fairly easily as a simple spring plus a rather large retardant force. Something like:

a = max(abs(k*y) - f, 0) * -sgn(y)

Where a is the acceleration, k is the spring coefficient (decrease for a car that tends to bottom out), f is the frictional constant (decrease to make the car bounce a lot), and y is the displacement from the car's resting position. You can throw in gravity, too, if you want, but alternatively you can just consider it as represented by an offset resting position.

How appropriate. You fight like a cow.

[edited by - sneftel on November 6, 2003 3:16:57 AM]

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Does the car suspension goes up and down on one axis? or does it do a part of a circle with a certain radius?

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yeah, up and down. The movements outside the axis is transfered directly to the wheel.

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You can model the suspension as a spring with a damper... The force exerted by the spring-damper on the car is:

F = k x + c dx/dt

where

k = the spring constant (higher value = stiffer spring)
c = the damping constant (higher value = more damping, will stop the car from bouncing up and down as much)

x = the distance from the equilibrium position
dx/dt = change in distance with respect to time (i.e. the velocity of the car relative to the wheel)

This is the most realistic way to do it as far as i know... The way i was taught to do it on my Mechanical Engineering course in any case.

once you have the force you''ll need to find the center of mass of the car, and figure out how that force is going to affect the car (i.e. make it rotate + move).

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I think it should be a circular movment around a radius, otherwise the distance betwen the wheels will change and thats really bad.

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hmm, the distance between one wheel and another wheel? or the distance between the wheel and the car?

the distance between the wheel and the car does change, thats the whole point of suspension... if the distance didn''t change then the wheel would be rigidly fixed to the car and you wouldn''t have any suspension at all...

you''ll want to model it as a simple up and down movement... i don''t know what u mean about a circular motion

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Suspesion has one degree of freedom. (up/down movement)

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all motor vehicle shock absorbers are set at inclined angles.

They point inwards and up.

Normal sedans and coupes are at around 5 degrees.

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