Losing connection at high throttle

Blue Robotics Software QGroundControl
1

when i using a lot of my thrusters at high speeds (like going forward and up at max speeds) my rov loses connection. it quickly regains the connection but i have to re arm it and that becomes cumbersome when i am trying to move under water. it this because of the high amount of current coming into the rov when i use all my motors. is it becuase my power supply only provides 14 volts and 30 amps? is this a problem with the fathom X and the fact that it is directly connected to my power and not through a buck converter. are there solutions to prevent this from happening.

1 Like
2

Yes, this is likely it. The total power draw of the ROV can easily exceed that. Each thruster can pull up to 25A, so if you consider all 6/8 of them, that easily exceeds 30A.
You can try lowering the pilot gain a lot, but you should consider changing the power supply.

3

would this be the only reason for losing the connection. my team members are saying that it is the fault of the fathom x. im defending it because it is a robust piece of technology but of would love to get the opinion of an engineer to clarify.

4

It all depends on how low your voltage gets. The regulator on the Fathom X is probably starving before the UBEC powering RPI+Pixhawk, which drops the connection and causes it to disarm before the voltage drops enough for these two lose power.

5

we reserved the UBEC to power the Pi and the pixhawk,not the fathom x. we are powering the fathom x by directly connecting it to our power distribution block which power everything on the rov like the escs/thrusters

6

2 things I have used on my surface powered system to eliminate this problem:

  1. Added a 5V switching regulator which allows me to drop to around 6.5V input in conjunction with 2 Farads of backup capacitors and an ultra low dropout regulator for the FathomX (actually the LX200V20 module directly). The Raspberry Pi, Pixhawk, and LX200V20 are all run from the caps which give about 5 seconds of operation even after power is removed.
  2. Change the pilot gain settings so the system will not disable or the voltage drop below 7V even at Maximum full stick command. Find this max gain via experimentation, then set you min and number of steps to give you an appropriate range.

Can I ask what power supply you’re running? Will it increase current and the output drops to maintain maximum output power?