Thanks a lot for your reply. I think it has pointed me to some resources I did not previously find.
I have a vehicle model dynamics and kinematics equations. Given certain actuator forces, the equations will be able to solve the velocities and pose of the AUV. This is similar to what GAZEBO does, but GAZEBO’s output is significantly different from my model, so I was keen on replacing it.
I think one way is to model my vehicle as an actor, and use my vehicle model to publish the velocities and pose to GAZEBO instead.
If you don’t mind me asking more questions, do you happen to know if it’s possible to publish a rostopic that GAZEBO can take in to update an actor’s pose? Also, if a sensor can be attached to an actor / be defined as an actor.