BlueROV2 Heavy Configuration Water Current Speed

Hello, I can’t seem to find the speed of water current that the BlueROV2 Heavy Configuration is rated to handle. I was wonder if their is a max speed and if different gains would effect that. We are looking to deploy ours in a river soon and want to make sure it can handle it and fight against the current to get back to us. Thank you

Hi @ssicari,

We don’t seem to have any public data for the heavy config speed limitations, so I’ve asked internally and will get back to you if we have any data from internal testing.

That said, the standard BlueROV2 is specified to have a maximum forward speed of 1.5 m/s[1], and given the heavy configuration has the same forward thrusters but a slightly larger cross-section its maximum speed will be below that. Note that “maximum forward speed” assumes only forward motion is being commanded, so if you’re trying to also command rotation or transverse/vertical translation then the maximum forward speed will be lower.

In short, yes.

The maximum speed occurs when the applied thrust in a direction is equal to the drag force resisting that motion. The gain scales down the pilot inputs, which reduces the thrust applied, and accordingly limits the achievable speeds.

It’s worth noting that:

  1. gain linearly scales the input commands from the operator
    • e.g. 75% gain reduces a 100% input to a 75% input
  2. drag scales with speed squared, not linearly/proportionally
    • 2x thrust only results in ~41% extra speed
  3. the T200 thrust response is not quite quadratic to its ESC inputs[2]
    • e.g. 75% input may be slightly faster than 75% of the maximum speed

  1. There is some internal disagreement about this value, so I’m hoping to get an updated one, once we’ve had a chance to do some testing. One person thinks the max forward speed may be more like 1 m/s than 1.5 m/s. ↩︎

    • ESC inputs are flight controller outputs
    • in manual mode, operator inputs are mapped almost directly to flight controller outputs, just with the pilot gain applied, and split out to the thrusters using the vehicle frame contribution factors

Hi @ssicari -
When operating a BlueROV2 in a fish pen, with a 1KW power over tether system (Outland), I’ve been able to overcome currents of up to 1 m/s in the past (at full power.) I hope that anecdotal report is helpful!

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Thank you for letting me know!