Hello.
I have one problem on my bluerov
4 motor spins when pixhawk is armed. I have tried to tune this in RC 1,2,3,4,5,6 settings, by chaging zero point. But when i change zero setting in RC 1,2 (noting happen). My ps4 controll is calibrated. I don’t have bluerov esc, i have cheap esc bidirectional from ebay.
My questione is. RC 1,2,3,4,5,6 mean channels like rx rc receiver or? I tink i need to find the settings in qgroundcontrol for zeroing the thruster, but where?
Hi @Fjosen, welcome to the forum 
The messages that get sent in are RC Inputs, the first 6 of which correspond to vehicle motion axes. The RC Outputs correspond to the PWM values sent to the Pixhawk outputs (you can check them with the SERVO_OUTPUT_RAW message in the MAVLink inspector). You can read more about the RC Inputs/Outputs here.
Are you using the ArduSub firmware on your Pixhawk, or something else? I expect any bi-directional ESCs that take PWM input should have a 1500 us pulse-width as their zero/stopping point, so this behaviour seems odd unless you’re in a controlled flight mode (e.g. not manual mode), or you’re not using ArduSub.
I use ardusub and qgc. Manual mode.
But where can i adjust zero for eatch thruster channel?
Thanks.
As far as I’m aware that’s not a feature that exists in ArduSub at this stage.
It’s possible it’s a joystick drift issue though - you may have some luck enabling and calibrating deadbands for your controller
Hello! I know this post was from a long time ago, but I wanted to check in and see if you ever resolved the issue. I have a similar problem happening on my system. I’m using a pixhawk to control 3 T200 thrusters, and two of them are immediately spinning when armed despite there being no joystick input.
Hi @fishbot -
Welcome to the forums!
Are you in manual mode? On the pwm outputs page in BlueOS what numerical values do you see next to the 3 channels the running thrusters are connected to?
Hi @fishbot, welcome to the forums 
To better understand your setup (and narrow down the cause of the problem):
- Are you using Blue Robotics Basic ESCs?
- If not, are your ESCs programmed to be bidirectional?
- Are you arming in manual mode, or a stabilising/automatic mode (which is expected to run the vertical thrusters when the vehicle is not perfectly level)?
- Which ArduSub version are you running?
- Which control station software are you using (Cockpit? QGroundControl?), and which version of it?
- Have you adjusted the default joystick axis mappings in that software?
Thank you! Yes, I am in manual mode. I am actually using QGroundControl to configure the Pixhawk and test the joystick control. Using that software, I can see pwm values of: motor 1=1500; motor 2=1900; motor 3=1100. The thrusters jump to this immediately after arming.
Edit: Another relevant detail is that I am using a Simple ROV-3 frame.
Thank you!
- Yes, I am using the Basic ESCs that came with the T200s.
- I am arming in manual mode through QGroundControl.
- I flashed the most recent stable ChibiOS Ardusub build onto the pixhawk.
- QGroundControl, version 5.0.8 64bit.
- I have not adjusted the default joystick mappings. I ran through the calibration using a logitech controller, but this issue occurs even when the controller is physically disconnected.
Thank you both for the quick replies to this old thread!
Hi @fishbot -
Have you calibrated your motion sensors?
Is the vehicle running BlueOS on a Raspberry Pi connected to your pixhawk?
Your thruster values suggest the vehicle is not running thruster 1, and thruster 2 and 3 are pegged running in opposite directions!
You’re also using a newer version of QGC then Blue Robotics has tested with / recommends - see the Technical Reference for links to QGC 4.2.8, or give Cockpit a try!
For deployment, we have a Raspberry Pi 5 running Raspberry Pi OS and sending pymavlink scripts to the Pixhawk (version 6c). My team is using this system for academic robotics research and we figured this would be the easiest way to incorporate our algorithms.
As for the thrusters, yes! That is what we are seeing. For some reason, arming in QGC immediately sends thrusters 2 and 3 into max and min thrust, respectively, and keeps thruster 1 at neutral.
Thank you for the recommendation about QGC. I think I might give the older version or Cockpit a try to see if that fixes it.
Another important note: I was not having this issue with a previous Pixhawk I was using. I am not sure exactly how, but the old Pixhawk burned out recently while I was manipulating it with the power still on, which I had not noticed. I was not having these issues with the old Pixhawk I was running. I swore I reconfigured this new Pixhawk the same way I did the one before, but something about this Pixhawk, or maybe the way I set it up, is causing this issue.
Edit: Sorry, I realized I forgot to answer one of your questions. I calibrated the built in gyro and accelerometer.
Hi @fishbot -
I think you’d find running BlueOS on the Pi would make many things much easier! Another improvement is running the autopilot on the Pi, as using lua scripts with a Navigator would be easier to develop for (and is not (yet) possible with external autopilots.) This guide alludes to some of the advantages, as does the overall intro to BlueOS.
It’s worth checking your parameters to make sure your trim is properly set for those channels, as well as the servo function for them. You could also review a log file to check that the joystick isn’t sending strange values as Eliot mentioned, for the RC input / output. Sharing a .BIN or .tlog file in general would help us debug what is going on!
Hi everyone, I resolved the issue in a very embarrassing way… Just had to reboot my laptop 
Posting more details for anyone else who comes across this issue:
I totally wiped the pixhawk, then reflashed it with ardusub chibios, recalibrated my accelerometer and compass (not gyro, I misspoke in an earlier post), and changed only the few parameters I needed to get it to work, based on what was working a week ago with my old pixhawk. I then tried arming it and, to my surprise, all 3 of the thrusters went off instead of just 2. I poked through the settings and realized that I had forgotten to change the frame to Simple ROV-3, so I did. Then I armed again and only thrusters 2 and 3 went off! So it seemed like this might have been an issue with QGroundControl sending some extra signals during the arming process. At this point I rebooted my laptop and tried again, and the problem went away! I am not sure if this is exactly what was going on, since I also now seem to have some issue where the pixhawk only can communicate to QGroundControl if I connect it to certain ports on a new USB extender I just got for my laptop, whereas previously I could just plug it in directly to one of my XPS 13’s USB-C ports and could connect QGC to the pixhawk with no issue. But this seems like it has more to do with my laptop than with my vehicle, so I’ll troubleshoot that at another time.
Thank you both for your help @tony-white and @EliotBR !