PX4 Community Q&A: June 21, 2023

June 21, 2023

Join us


  • Community Announcement
  • Community Q&A
  • General Discussions

:loudspeaker: Community Announcement

A.1: v1.14 Release update

  • We have couple of release blockers, after resolved we will have release candidate
  • If you have a drone to contribute, it would be helpful to get more testings!
  • Perhaps v1.14 release features showcase event? (release party)
  • E.g. new actuators setup QGC workflow

: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: HITL with Tiltrotor bug report - Darrens

  • Works in SITL, but in HITL the motor ouptut is too low for some reason
  • Standard VTOL works fine in HITL, but tiltrotor isn’t.


  • MAVLink interface for HITL is quite jenky. Why is HITL necessary?
  • To debug, first debug what the output of actuator goes through for mavlink ↔ sitl gazebo. Then, check what’s the pipeline for HITL for motor outputs
  • Check: Control allocator setup / simulator_mavlink for SITL and mavlink module for HITL
  • Make sure to figure out how the tiltrotor VTOL SITL is working fine, and where HITL differs from SITL for that.

Q.2: Offboard causing drone to flip in v1.13.3 - Aiswarya

Flight log: https://review.px4.io/plot_app?log=e3878cb0-6fe4-4ee4-9108-58cf4f388f52

Our drone was accepting mavros commands for arming, takeoff, etc but when I set the mode to offboard the drone immediately flipped and started behaving in an unstable way. I was publishing local position z value before I switched to offboard mode. We are using our quad with pixhawk 6x fc and px4.

  • Offboard setpoint is local position message
  • Have tried takeoff and landing, and works

Another log: https://review.px4.io/plot_app?log=011ffcda-4444-42a0-a443-dab8b8ed2325


  • When the motor directions were all switched, as soon as yaw control is induced, it may cause a flip. So check motor directions! - Mark
  • Perhaps the position setpoint was too aggressive, and maybe current offboard control can’t handle that - Daniel
  • Try out manual mode and apply aggressive inputs, and make sure vehicle can track the attitude/rate well. Issue may be from rate controller.

Analysis from Matthias:

Try to find the rate control issue in Stabilized/Manual mode by flying aggressively. If found try to tune such that it does not get unstable in this case.

When switching to offboard initialize the setpoint with the current vehicle state and then start moving it gently when you were able to take over.

Q.3: QGC Herelink telmetry not working with Cube Orange - SJ

Is there any work being done to update QGC Herelink Radio telemetry . I am currently on a Beta 1 update version and things are not working as required with the CUBE Orange

  • Herelink has their own fork based on 5.12 Qt, but it’s likely very outdated
  • Ramon also pinged cubepilot team, will get back with answer

:thinking: General Discussions


  • For lawnmower application
  • int data type for altitude limits precision to around 10 centimeters!

Suggestions from SLG robotics:

  • Rename lattitude to lat_deg, to make search through code better and make unit more explicit


  • If we change the data type, let’s change the naming as well, to always catch these migration cases in e.g. Flight Review
  • Change altitude members into float (achieve 0.1m precision), and rename to append unit

D.2: Switching External vision ↔ GNSS Fusion - Farhang

Currently in internal development with Ascend Engineering. Is it useful for PX4 in general?