2009-03-02 17:21:22 UTC
Hi Martin, I'm probably just confusing myself as usual but I'm having trouble with modelling different inertias in a multi-body system like a car.
Currently I have a simplified model - there's one inertia tensor and mass of the whole car - i.e. the sprung plus unsprung masses.
Road forces (i.e. on the tyres) are split between verticle and horizontal components. The horizontal components act on the whole car object for accelerating and turning. The verticle components act only on the wheels and thus effect the suspension forces.
The verticle suspension forces (in the spring-dampers) act on the car body and the wheels (naturally they push the wheels down to the road and keep the body up).
Although this methid works a treat and feels about right, the thing is the suspension is trying to accelerate the inertia mass of the whole car, which isn't quite correct...I think the suspension should work on just the car body inertia but, I can't figure out how to have two inertia systems working on the one object.
Obviously, all external forces work on the whole car inertia mass but the 'internal' suspension forces work only between the wheels and the body.
Is there a better or more correct way to model this type of multi-body system?
