Thrusters not working

[rune (Rune Andrè Hansen)]

Hi
The thrusters on our Bluerov heavy topside powered ROV suddenly stopped working today during a job.
There is a audible ticking sound and when I feel some of the thrusters I can feel some small vibrations in the thruster motor when the ticking sound comes.
When starting the system there is no “startup” sound from the thrusters, but when powering off the system, the sounds comes briefly from the thrusters.

Have any of you encountered something like this?

-Rune-

[EliotBR (Eliot)]

Hi @rune,

Apologies for the delay on getting to this.

@rune

The thrusters on our Bluerov heavy topside powered ROV suddenly stopped working today during a job.
There is a audible ticking sound and when I feel some of the thrusters I can feel some small vibrations in the thruster motor when the ticking sound comes.

If the thrusters stopped working without changing any parameters or software configuration then my main thoughts would be around

• power supply
  • perhaps there’s a short somewhere, or a leak causing corrosion and accordingly some extra resistance
• something caught in the thrusters
  • if the vehicle has been driven through some fishing line or material has built up inside the thrusters, although it’s surprising that all thrusters are apparently not working
• damaged thrusters
  • again, it seems odd if this happened to all thrusters at exactly the same time

@rune

When starting the system there is no “startup” sound from the thrusters, but when powering off the system, the sounds comes briefly from the thrusters.

That’s very confusing. The ESCs audibly vibrate the thrusters on startup to indicate that all three motor phases are detected, and then make a couple of longer sounds to indicate that they’re receiving a valid (1100-1900us pulse-duration) and neutral (1500us pulse-duration) PWM signal. If any of the first three beeps aren’t occurring for a thruster then there’s an issue with its connection to its ESC - perhaps the cable is damaged, or the ESCs aren’t getting power when the system is turned on. If the last two beeps aren’t occurring then there’s an issue with the signal being sent to the ESC.

It doesn’t seem likely for this to occur for multiple thrusters simultaneously unless there’s some kind of system-wide electrical issue (like no power), but then it doesn’t make sense for things to suddenly briefly work when the system is being turned off.

It may be helpful to know which specific sounds the thrusters are (and aren’t) making at each point of the process.