T200 Thruster Configuration

General Discussion
2

Hi @Tamim, sounds like an interesting project :slight_smile:

This will depend on tether thickness+weight, the smoothness of the outer jacket material, and what it’s against (e.g. floating in water should have less drag than if it’s against the edges of the tunnel).

That depends mostly on the shape, and motion speed. Depending on the precision requirements of your use-case it may be worth doing some fluid dynamics simulations to determine the most drag-inducing areas and smooth them out where possible.

Sorry, not sure what you mean here. It’s not clear which thruster(s) you’re referring to, or which direction you would be moving them ‘along the yellow panel’.

Distance between thrusters is mostly important for efficient rotation (away from the center of mass → more rotation torque from the same thrust), along with whether they can interfere with each other (if they’re very close together they can "steal each other’s water’’ in a sense, or you could have one changing the direction of the flow from another one, which reduces the resultant force in the desired direction).

That’s reasonably simple to do, but depends a lot on your configuration. See our T200 technical details for information about the performance depending on thruster supply voltage, forward/reverse thrust levels, power usage for a given voltage and control signal, and other relevant information.

The force caused by a single thruster (assuming an unrestricted water flow in and out) can be represented as below:

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where

\begin{align} \color{blue}F_{\uparrow} &= F_T \cdot \cos({\theta})\\ \color{red}F_{\leftarrow} &= F_T \cdot \sin({\theta}) \end{align}

and F_T is the thrust as specified in the technical details, for your operating power and control signal.

When you have mirrored thrusters left to right the horizontal thrust forces will cancel out when you’re going forwards, so you’ll have a net forwards thrust unless you have more drag going one direction than the other (depends on your ROV shape and balance).

Also take care to consider the propellers you’re using - if your propellers are mirrored between the front and back then your thrust forces will be from 4x forward and 4x reverse thrusters, but you may wish to set up the propellers so that all 8 thrusters are using ‘forward thrust’ when the ROV is going forwards. and ‘reverse thrust’ when the ROV is going backwards, which would make going forwards faster than going backwards.

Have a look at these two threads - they go into quite a bit of detail: