We loved your 3-thruster build! Thanks for using our components and the ArduSub control system. I’ve been working with the software team to overhaul that documentation, so if you have recommendations, I would love to hear them while I continue working on it.
You’re right, we haven’t described the pros/cons for each frame type yet. It feels like it would be a white paper in and of itself. Much of the discussion on underwater vehicle physics and thruster placement is described in The ROV Manual. Generally, less thrusters = a cheaper vehicle, more thrusters = more maneuverability. That’s the tradeoff.
Simple-3 Frame: Simplest and cheapest frame design. Without a “heading hold”, the vehicle will yaw due to the torque and bite from the vertical thruster. Not really much of a problem with ArduSub as heading hold is engaged in either Stabilize or Depth Hold modes. No strafing capabilities.
Simple-4 Frame: Adds an additional vertical thruster spinning in the opposite direction. The vehicle will not yaw when moving diving or surfacing and will stabilize in the roll direction. No strafing capabilities.
Vectored: Changes the horizontal thruster configuration so that movement in any direction in the horizontal plane is possible.