Q. 

Took the ROV out for a test dive. Any attempts to engage Station keeping or to turn on pitch hold or roll hold caused the ROV to perform backflips. Can you give your advice?

 

A.

The issue could be caused by a falsely configured DVL.

How to set the roll and pitch mount angles in Mobula:

  • Make sure to input the mounting offset angles in the Mobula Config program otherwise the velocities will be rotated falsely.


     Figure 1: Mobula Config with DVL mount angles

How to test it:

  • Open Mobula and add a dashboard with live data for velocity x y and z
  • Move the ROV with a joystick.
  • Expected: The velocity dashboard values are working as expected (see table below) and station keeping works.

    Forward movement
    		Only positive x values
    Backward
    		Only negative x
    Starboard
    		Only positive y
    Port
    		Only negative y
    Down 
    		Only positive z
    UpOnly negative z