Depth hold issue

Not sure if this is the correct location for this topic, but here we go.

During testing of the ROV I have ran into a rather peculiar issue. When pressing dive mode for depth hold the ROV sits perfectly still…down to 8 meters or so. Deeper than that, if I press depth hold,it will return to 8 meters before holding the depth. I tried to reboot and did the same again: Went down to 10,5m - 11m and pressed depth hold. The ROV immediately ascended to 8 meters and stopped. Any suggestion on how to solve his anyone ?

Are you able to ascend and descend freely between 0~8 meters? Do you have the GeoFence option checked on the safety page?

Jacob
No problem do dive deeper in stabilize mode and manual mode. When pressing the depth hold button the ROV returns to 8msw and stays there. Pressing the depth hold anywhere between 0-8msw works fine, the ROV then stays exactly where it should…just not below 8msw. The depth fence is set to -100 - report only

Uncheck the depth fence option, and you should be good to go.

I just fixed a bug in QGroundControl this morning where the Max depth value in that field was not set correctly, your maximum depth was probably set to the default of 10 meters.

If you do want to set the maximum depth in software set the following parameters:
FENCE_ENABLE: Enabled
FENCE_TYPE: Altitude
FENCE_ACTION: Warn Only
FENCE_ALT_MIN: -100m or whatever limit you want
FENCE_MARGIN: 0, or added buffer to stay away from limit

Note that the limit is only enforced in depth hold mode.

Thanks Jacob
I had the settings like you describe but the issue still remains. One more thing: When in flight mode, is the pilot suppose to be able to still adjust the depth with the stick, without having to go out of depth hold mode? I am not able to do so when in depth mode, but I would sure like to. ?

Yes, this is the intended behavior. It sounds like something else is wrong. Can you please email support@bluerobotics.com so we may resolve this quickly. We can post the resolution here.

Oystein purchased his ROV before December of 2016, and was running an old version of ArduSub. His issues have been solved by updating the ArduSub firmware on the Pixhawk.

Hi Gentlemen, I’m having trouble on the depth hold mode as well. When I activate the depth hold mode, the BR2 starts shaking on the Roll axis. Depth hold mode seems to work in a very wide range of about a meter or so. I’m still in the phase of pool testing. My BR2 is brand new, all other modes seems to be working fine. I’ve already tried to decrease roll gain, but no changes were noticed. I thank you in advance for your support!

@Inglez You need to make sure your motor directions correspond to the defaults in the Software Setup

When you pull the right joystick down (to descend) then the vertical thrusters should be pushing air upwards (as if the ROV was diving). If this is incorrect, then the vertical motor directions will need to be reversed.

Use the motor calibrating set-up menu. if you change direction manually in mot. control then it still might not be ok.

Thank you for the response. I’m understanding that the calibration setup menu is this one, correct?

That is correct. Make sure the air flows the same way as the water should do during operation. Lets hear about the result.

I’ve just checked the configuration again and it is correct. Pushing the lever down, the ROV dives deeper into the water. Motors 1,2 and 5 are “reversed” so that everything works fine.

At initial setup, number 6 was reversed and number five was not. So it was working in the opposite of the lever command. After reversing number 5 and uncheck number 6, it follows the command lever, although the behavior is just exactly the same in the water. It rolls quite fast from one side to the other, in a short amplitude, and depth is not hold.

Just as additional information, when it is in the water, it sits quiet and well balanced.

Checking other threads, I found about “Roll stability issues” and tried reducing the ATC_RAT_RLL and ATC_ANG_RLL_P (I’ve tried reducing them individually and simultaneously. Nothing changed.

Following another tip I’ve found in the forum, I’ve reset ATC_RAT_RLL and ATC_ANG_RLL_P values to original and I’m reversing motors 5 and 6 in the frame. Is this a way to go? Any other suggestion?

Bests!

Just finished testing after motor 5 & 6 switch. It was definitely NOT the way to go. BR2 started spinning after “depth hold” mode was set.
Now I’m back with previous setup.

Strange. I had the exact same issue. Everything worked in manual mode but went limbo in depth hold mode. I solved the problem by adjusting the motors in the. How is your horizon ? Is the pixhawk set to Roll90? Can you share a short video with the rov in the water operating in manual and then switch to stab mode and further into depth hold ?

Horizon looks ok. Pixhawk is set to Roll90. All calibrations are green lighted. (Calibrated 3 times already because the behavior of the BR2 really looked strange. No changes were noticed…)

Here is the link to the video.

Hello Raphael,

At first this looks like PID issues. Try resetting to the default parameters.

Are you running Ardusub 3.5.4? There were significant changes in depth hold froom 3.5.3 to 3.5.4.

Also, how is the ROV behaving in stabilize?

I’ll reset to the default parameters. To make sure we track down the issue more precisely, I’ll do one modification at a time, so we’ll end up with a precise conclusion .

FYI, I ran all updates when seting up the BR2, but I’ll do them again if step 1 does not solve the issue.

Btw, what exactly mean PID?

Come back to you later.

Just check in QGC summary what is the version of Ardusub:

Proportional-Integral-Derivative Controllers.
It is the code/math actually trying to control the ROV. ATC_RAT_RLL and ATC_ANG_RLL_P are some of the gains of these controllers.

I’ll be around!