Physics Programs

ID #1042

What is the difference between the three accelerations (Fwd Acc, Lat Acc, Vert Acc) and u-dot, v-dot, and w-dot displayed in Key Results?

u-dot, v-dot and w-dot are the vehicle-fixed accelerations (Fwd Acc, Lat Acc, Vert Acc) transformed to the earth-fixed (inertial) reference system.

The equations of motion (F=ma) are calculated in the vehicle-fixed reference system. But this may be a rotating reference system, so there is a transformation required to calculate the accelerations in an inertial (non-rotating) reference system. u-dot, v-dot and w-dot are the results of that transformation. u-dot, v-dot and w-dot are required because they are the accelerations that are integrated to calculate earth-fixed velocities and positions. They otherwise have no physical meaning.

For example, when a vehicle is cornering, the occupants feel the lateral acceleration (Lat Acc), NOT v-dot!

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Last update: 2011-08-22 20:19
Author: EDC
Revision: 1.0

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