05. Tracking 3D Dynamics Overview
Nd787 C3 L4 A04 Tracking 3D Dynamics Overview V1
More about p,q,r
These "body rate" variables p,q,r can be a little confusing. A few things to note about them:
1. The "p" has nothing to do with pitch!
And r has nothing to do with roll!
These three letters were just chosen because they occur sequentially in the alphabet, just like x, y, and z. In fact, p gives the angular rotation rate about the x-axis (in the body frame), q gives the rotation rate about the y-axis (body frame) and r gives the rotation rate about the z-axis (again, in the body frame).
2. They aren't the same as the Euler angle rates of change \dot{\phi}, \dot{\theta}, \dot{\psi}.
While both of these give some sort of angular rate of change, the body rates are calculated in the body frame of the vehicle while the Euler angles are expressed in the world frame.
3. They really are body RATES!
Even though they don't have dots over them. This means that \dot{p}, \dot{q}, \dot{r} actually express rotational accelerations.