# Calculating angle from body-fixed moments on a ridig body

1. Jun 22, 2012

### Larsen1000

Hello everyone

I have some problems figuring out the correct way to calculate my rigid body angle based its local moment. I am working in R3 space.

I have the rigid body local rotational acceleration expressed as a function of distance to fulfill a rigid body constraint:

AlphaL = F(x,z) * l(x,z) I

I want to find a way to updating my rotation matrix in each iteration expressed by the equation for rotational acceleration equation.

My first thought was to numerically integrate the local angular acceleration to get the local angular velocity. To get the angles I am using the the directional cosine matrix to update the rotation matrix.

Am I thinking correctly?