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Trouble with Lights, Gripper, and Gimbal

Hi there,
So in essence, every aspect of the robot except for the thrusters does not work. We tested and determined that power is going through everything, but when plugged into the pixhawk, nothing seems to work. I’m completely lost as to what’s goin on. When we try to map the Newton Subsea Gripper Buttons, the option for “servo_n_min_momentary” and “servo_n_max_momentary” do not appear. Does anyone have any solutions?

Not sure what you mean by this. I’m assuming you’ve used a multimeter to determine that your power/ground wires are correct. It sounds like you’re using QGroundControl to control your ROV - have you made sure you’ve plugged in the wires for your accessories correctly, and that QGC has them mapped correctly (e.g. lights channel → the pixhawk output port you’ve actually plugged them in to)?

More generally, what operating system is your computer using, what ardusub, companion, and QGC versions are you using, and what have you done so far to set up the connections and test them, which has lead you to determine that they don’t work?

The fact that the thrusters are working would imply that the QGC, the pixhawk, the companion computer, and your ESCs are all working to some degree, which is a good start. You haven’t mentioned the camera, so not sure if that is or isn’t working. By the ‘gimbal’ do you mean the servo that tilts the camera up and down, or have you got a custom setup that does something different/more advanced?

My best guess with the information so far is that you haven’t specified the ports for your components correctly, but there are several other possible hardware and software issues that could potentially be the issue. Without further information/testing from your side it’s not possible for us to specify what the solution is, because we don’t know enough to know what the actual issue is.

Hi thank you for responding.
Let me answer some of your questions:

  • Yes we used a multimeter to ensure that power and ground are correct.
  • We are using QGroundControl to operate the vehicle
  • We made sure and repetitively checked that the wires are sent to the right outputs, and when assigning the appropriate ports to the lights they would still not activate.
  • We are using the latest version of Windows 10 on the computer and the versions of QGC, pixhawk, and Ardusub are up to date by the documentation provided by Blue Robotics.
  • The camera stream works perfectly
  • The gimbal does refer to a servo that we have mounted to the front of the enclosure. We only use a 3 output servo. while it is getting power and has moved before, we cannot seem to control it by controller or other means. It does however initialize upon startup
    How do I specify ports for the Grippers as I cannot see any of the parameters to configure such a thing. Additionally, the lights do not seem to deliver any sort of output even though they are receiving power. If you have a solution, could you please detail the process to which we can fix it?

Check this parameter: BRD_PWM_COUNT: It sets how many Aux ports can be used for PWM.

Also can you tell us what Aux ports on the Pix you have the camera tilt servo, gripper, and lights PWM leads plugged into.

I will try to check that parameter when I work on it in a few days.

  • The grippers are in aux 1 and 3

  • 2 lights are merged to one wire into port 7

  • Gimbal is in port 8

But we typically change these around to test.

I will check back in on Thursday with an update.


Changing the BRD_PWM_COUNT from 4 to 6 didn’t seem to help as much as we expected. Here are visuals to illustrate the problem at hand.

For the gripper, there is no button assignment for the “servo_n_min_momentary” and “servo_n_max_momentary.”

The issue with the gimbal and lights have been resolved (simple hardware difficulties). The grippers are powered but we cannot control them.

If you click and drag on that button assignment menu you can access the remaining options. You can also try typing ‘s’ when you open it to jump to one of the options that starts with ‘s’. At the very least there should be options for ‘servo_n_inc’ and ‘servo_n_dec’ and a few others. Let us know if that still doesn’t display the momentary options :slight_smile:

Glad to hear those have been sorted out - always good to make progress :slight_smile:

Hopefully fixed soon!

We finally fixed it after months of difficulties. Similar to what you said, we changed the BTNn_FUNCTION in the advanced settings for the parameters tab to the value corresponding to servo_inc and servo_dec, as highlighted in the parameters documentation (as ours were in aux 1 and 3, these values were 61, 62, 71, and 72 for opening and closing). While it did say that these were unknown parameters in the button assignment page, it did end up working. Thank you all for your help!! Wouldn’t have done it without you.

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Glad you’ve managed to sort out the last of the issues - now you get to have fun using your ROV! :smiley:

Thanks for posting the solution that worked for you - hopefully others will find it useful later on :slight_smile: