Willian asked me to draw up a quick schematic for you:
Using Aux pins 1 and 2, you should be able to control opening/closing with a joystick button mapped to
, and rotating left/right with a joystick button mapped to
. Momentary means that each press sends a short burst, which should help to provide relatively precise control over its movements.
Note that the example ESC that Willian linked to seems to only be rated to 2-3 LiPo batteries in series, and has a supply voltage range of 6-12.6V (at least according to the image), whereas the BlueROV2 uses a 4S battery (nominally 16V), and you’ve said your gripper requires 14-18V, which is the range for a 4S battery. Accordingly, you’ll likely need to find a different one that accepts the higher voltage level (it may help to search for something like
brushed ESC 4S.
Without knowing which gripper you’re using and what it’s set up to do, we’re a bit concerned that you haven’t mentioned limits or end-stops. Assuming it is effectively just two DC motors, with no in-built limits to stop over-rotation or opening/closing beyond the limits of the mechanism, you’ll have to be quite careful when operating it to make sure you stay within its operating range.