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.

If it is possible to have Heading hold working, it relates most likely to the incorrect setup of the vertical thrusters.

The thrusters direction has to be setup correctly in order for the controllers to work.
Some manufacturer tend to come with different default settings so the thrusters sometimes do not spin in the direction they should. In this case you need to go and change the thruster rotation direction in the Mobula software.


How to set the thruster rotation direction in Mobula:

  • Open the Thruster properties.
    Here you find the configuration options for each thruster, eg Thruster 3 Clockwise.
    Set the rotation direction properly.

    Figure 1: Heavy frame with Thruster properties.
     
  • The Thruster order for the heavy frame is (where h is horizontal and v is vertical):

    Thruster 1hstbd front
    Thruster 2hport front
    Thruster 3hstbd back
    Thruster 4hport back 
    Thruster 5vstbd front 
    Thruster 6vport front
    Thruster 7vstbd back 
    Thruster 8vport back


 

How to test it:

  • When the ROV is on the surface, use the joystick and attempt to dive.
  • Expected: All four vertical thrusters should push the water up.