Simulate a AUV in SimuNEX

[leebissessar5]

An AUV (Autonomous Underwater Vehicle) is a class of UUVs (Unmanned Underwater Vehicles) that can be considered an underwater counterpart of an UAV (Unmanned Aerial Vehicle). As they operate underwater, they experience a multitude of environmental forces such as drag, lift, buoyancy, and added mass.

Added mass is a unique force that acts on the acceleration of the moving body. Since the magnitude can vary across DOF, the simplest way to implement an acceleration-based force is by using a mass matrix $M$ and operating the physics engine in acceleration force mode by using the formula: $a = M^{-1} \times F$, where $F$ is the 6DOF applied force and $a$ is the 6DOF acceleration.

New to SimuNEX is the implementation of control surfaces such as fins which allow for movement underwater along with propulsion. Just like the PropellerFunction, an equivalent FinFunction would be implemented for fin dynamics as a MotorLoad object.

TODO

• [x] Implement drag forces (linear, quadratic, cross-drag etc) (see 5028e87)
• [x] Implement buoyancy (see 222f3c5)
• [x] Implement fin forces (see 576f66c)
• [x] Implement added mass forces (see 3f073b9)

[leebissessar5]

All AUV forces have been implemented and tested! Will close with an associated PR.