HELLO.
When i use joystick to control the two thrusters that can make ROV move forward，QGC shows lost manual control.
It look likes that this two thrusters can only get the signal one time，i can not control these constantly.Because after moving button，the rotational speed of the two thrusters almost do not change,and a few seconds later,the QGC shows lost manual control.The QGC disarmed itself.Well,other thrusters can work normally.
So what is problem,the two thruster used to work normally.Must i replace these with two new thrusters？
It seams that you have power issue that restart your companion or the Pixhawk.
Are you powering your ROV from the surface?
Yes,i use switching power supply to powder my thrusters，it output 48VDC.
I notice that my companion or Pixhawk does not restart.Because the QGC just show’lost manual control’,then disarm my ROV,i can arm it after this.
I think the power is enough,because i make the thruster rotated in the air.The current should be low.
Hi @Richard1, a few questions:
- What thrusters are you using, and are they rated to this voltage?
T200 Thrusters are only rated to 20V, so I assume you’re using something custom / from elsewhere?
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Do the telemetry and video stream continue, or does everything cut out?
If the video stream continues then it’s at least not a Companion computer restart issue, and if the telemetry continues then it’s possibly a Pixhawk issue but not one caused by restarting. -
How is the Pixhawk powered? Does it have a direct regulated connection from the main power supply, or is it only powered via the Companion computer USB connection?
- Were you using all the thrusters at the same time when testing in the air? What about when it cut out while in the water?
Power availability depends on the supply capacity compared to everything that’s drawing power, and if several thrusters are operating at the same time that can use a lot more power than one thruster at a time, which may cause the control electronics to not have enough power.
How long it takes to recover from the “lost manual control” until you can arm it back again?
You can keep pinging you companion computer with running this command in the terminal “ping 192.168.2.2 -t” to check if raspberry pi suffered from a power lose.
I use other thrusters and make the ROV by myself.
I think the telemetry and video stream continue.I use 5VDC power supply to power pi,the Pixhawk is powered by pi with usb interface.
I do not use all thrusters to test.My power is enough if i do not use all thrusters at the same time.
Well,after several days,i test my ROV again.The problem is gone.All thrusters can work normally.And QGC do not show ‘lost manual control’.That is wired.Because i change nothing.
Ok 
It’s recommended to supply the Pixhawk directly from a 5V power supply, because the Raspberry Pi may not be able to provide sufficient power to it, especially if there are also other USB peripherals connected.
Glad it’s working now then at least
If it happens again my main suspicion would be Pixhawk powering, but feel free to post follow-ups if you’re not able to get it working consistently.