# Coordinate System

## Global Frame

The global frame is such that the x,y origin is at the pinger, and z=0 is at the surface. Positive z is up. Yaw is relative to magnetic north. Pitch and Roll are relative to the gravity vector.

## Axes

• X+ - front of the sub
• Y+ - left of the sub
• Z+ - above the sub

## Rotations

• Yaw+ - Counterclockwise around Z+ axis (this is opposite of magnetic) (Yaw Left positive)
• Roll+ - Counterclockwise around X+ axis (Roll Right is positive)
• Pitch+ - Counterclockwise around Y+ axis (Pitch Down is positive)

## TF Frames

• world - Global frame defined above
• cobalt - The frame defining the sub's orientation relative to the world frame based upon the localization node output.
• cobalt_sim - The frame defining the sub's orientation relative to the world frame based upon Gazebo's output.

### TF Graph

A visual representation of the TF tree will be placed here in future.