IMU and ultrasound sensor fussion for the underwater vehicle loclization

edit

HI

I would like to add some sensor feedback in order to perform a vary basic controller on an underwater robot..So I would like now to use the fusion of the IMU and the ultrasound sensor pointing down (to the sea bottom) to get some localization (so to know the distance the vehicle traveled) when i apply force to the actuator( velocity) in one direction. So the vehicle move just straight forward ,and I would like to know the distance traveled. So is it EKF a solution for such thing or I have to model own sensor fission?

At the moment the robot is simulated in gazebo with virtual sensors (such as IMU, ultrasound, camera, Pressure) . So i just want to check the simulation.

Any help?