PX4 Community Q&A: July 26, 2023

July 26, 2023

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  • Community Announcement
  • Community Q&A
  • General Discussions

:loudspeaker: Community Announcement

A.1 :

:people_holding_hands: Community Q&A (No deep technical discussions)

:exclamation: Guideline for asking a Question

  1. Specify what you are trying to achieve
  2. Specify what environment / platform you are using
  3. Prepare a Link or Document to help understand if possible
  4. First, ask the question on Discord or create a Github Issue!
  5. If you take over 5 minutes for the question, please continue in Discord or a Github Issue.

Q.1 : ICMA & BMI sensor data clipping - Peter

ICM sensor data are clipping out a lot, could it be filtered somehow?

  • Currently clipping at around 16G
  • BMI sensor isn’t clipping.


  • Some settings for the sensors have changed, may be realted to the result
  • You can reduce the priority of the IMU that’s clipping to make it secondary, not primary, then:
  • We could make it to have only the IMU that is actually being used to complain about clipping.
  • Could be even better to place Flight Controller on the outskirt of the frame to reduce vibration on it.
  • There also could be hardware hitting the Flight Controller, causing high acceleration
  • Check out clip count that is logged, and if it is a sustained clipping, and not sporatic, it could cause flyaway

Q.2: ICM chip question - Peter

ICM42649 chip does it exist?


  • Probably ICM 20649, and could be a typo

Q.3: CI improvement PR

Q.4: EKF2 recent updates summary - SLGRobotics

There was a lot of activity around EKF2 lately. Could you provide a birds eye view of problems and solutions related to that? Thanks!
I meant Github checkins in Main of course

Q.5: ROS2 - How to integrate custom uORB message

px4 messages repository getting updated via CI is time consuming, is there way to bypass this?


  • In the future, we want to have the PX4 be built via colcon itself, so we don’t have to sync these message definitions
  • Can replace message folder with symbolic link as workaround.

Q.6: Parameter save location customization

Having a FC with multiple locations of storage location use case.

  • Configuring parameter storage location via parameters isn’t ideal
  • We can rather place the symbol in the KConfig
  • The location should be set at compile time, not run time, so KConfig would be better option?
  • Currently parameters, waypoints, logging are ones we are discussing about.

Action Items:

  • Peter can create draft PR on using KConfig instead

Q.7: Plans for dropping Gazebo classic - slgrobotics

Are there plans to drop support for gazebo-classic? What is the long term plan for simulation?


  • After Ubuntu 20.04, it will be discontinued, so we will have to make the new Gazebo as the main development
  • After few tweaks, new Gazebo should be as usable / better as the classic Gazebo.
  • Timeline wise, we won’t be dropping classic Gazebo any time soon, so you can just use the new Gazebo (it’s a choice)!
  • Please try the new Gazebo, it’s fairly good :yum:Gazebo Simulation | PX4 User Guide (main)

Q.8: Estimation of wind in EKF2 without airspeed sensor - Junwoo

Is it possible to have wind estimate without airspeed sensor?

Currently it is assuming no side slip, and then tries to guess the wind speed. Should work only when plane is doing quite a lot of turns and wind is somewhat constant.

Q.9: ScheduledWorkItem vs WorkItem module stop behavior

Having a new module written as child class of WorkItem, instead of ScheduledWorkItem, results in a module when being stopped (via NSH), to not exit properly

Also, having the bool init() function defined in the header file of the module class results in error:

error: bit-field ‘bool MyModule::init()’ has non-integral type ‘bool (MyModule::)()’"

So it seems like there may be some issues in how I constructed the module, but no clue for now :person_shrugging:

Q.10: Pegasus simulator minimal setup to run - Andrew

Currently the requirement is quite high end, is there way to run it on low power environment / laptop? Would like to test on 4-core CPU.


  • This is quite NVIDIA specific, but still could be interesting to get it supported
  • In Academia people are utilizing this simulator more nowadays for Reinforcement Learning (also for Hardware testing)
  • Figuring out plugins for GPS, etc would be a consideration too.
  • We could use this as a ROS2 bridge example as well

Action Item: Jay and Daniel will keep it in mind and get in touch with the simulator authors in the future.

:thinking: General Discussions

D.1 :

Not sure if I can join, I will be driving during the meeting time.
Just if you could share comments on this, I appreciate it: Fix CI for deprecated set-output by farhangnaderi · Pull Request #21848 · PX4/PX4-Autopilot · GitHub