Just want to share my experience with you guys. When testing the new build in depth hold and stab mode, the ROV flippet along the pitch axis and acted really crazy. The reason for this was because the way I had designed the frame and installed the horisontal thrusters. Since the thrusters have more bollard pull in one direction (fwd) then it has in he aft direction I decided to rotate the aft thrusters 180 deg, and then invert the propeller in the motor settings. That obviosly did not not work and the result was the flipping. We rotated the thrusters back according to its originally design and everything works out as it should. Its kinda sad because I wanted all the horisontal thrusteres to face the same way in order to have most bollard pull moving forward.
Hi @SDI -
What you describe should absolutely be possible! Generally, if an ROV drives ok in Manual mode but goes nuts in Stabilize mode, you either have the autopilot orientation set incorrectly, or the direction of some thrusters set wrong, which confuses the autopilot. Flipping the thrusters back around, and letting the automatic motor-direction test run (from QGC or BlueOS Vehicle setup), with the vehicle floating in water, should get things working correctly!
The ROV operated just fine in manual mode, but went all acrobatic on sugar in stab mode. We checked the propellers rotation and all of them pushed the right way. We the proceeded to perform the automatic, in water automatic motor-direction test run (from QGC) The program inverted 2 thrusters for some reason. After this exercise the ROV did not perform well in manual mode and still flipped in stab mode. That’s when we turned the thrusters according to the heavy set-up figure and it all worked fine. Got me thinkin that somewhere in the code it will be “to much” if you have the thruster in the “wrong direction” and the propeller inverted. I will have a look at the other ROV and see how those thrusters are set (T200) but I know way back then when I made the first one I also wanted the max bollard pull forward.
Sidenote: Starbord aft propeller sometimes don’t want to stop spinning, even if we unarm the ROV. It rotates just enough to slowly yaw the ROV. We have to stop it by doing a soft restart in BlueOS.
Hi @SDI -
The thruster directions are frame dependent, based on the thruster matrix. It should be possible to achieve what you want, unless you were putting the thrusters at an angle the frame type didn’t expect.
If one prop won’t stop spinning, you can adjust the servo_trim parameter for that # thruster, by moving it slightly lower or higher you should be able to eliminate the issue…
Thank you. The thrusters are vectored according to original Heavy Config. Changing the output in the matrix was a neat solution.