Magnetometer system rotates with an incorrect angle

[gmsanchez]

Environment

• OS Version

Ubuntu 24.04 on a Docker container

• Source or binary build?

Binary
---
echo $ROS_DISTRO 
jazzy
---
gz sim --version          
Gazebo Sim, version 8.5.0
Copyright (C) 2018 Open Source Robotics Foundation.
Released under the Apache 2.0 License.

Description

According to NOAA Magnetic Field Calculators the magnetic field intensity for my location is

• North comp: 17,510.2 nT
• East comp: -3,045.2 nT
• Vertical Comp : -13,553.1 nT

• Expected behavior: After setting the spherical_coordinates to a latitude and longitude of my region, I expect the Magnetometer system to follow the rotations of the link it is attached to. For example, if I start a simulation with the magnetometer sensor initial pose of <pose>0 0 0 0 0 0</pose>, it is equivalent to say that the x axis is pointing to the North, the y axis is pointing to the East and the magnetic field message should read

magnetic_field:
  x: 0.17961739003658295
  y: -0.031671393662691116
  z: -0.12302243709564209

as it does, because the Magnetometer system uses a NED reference frame. If that sensor is rotated in Gazebo 90° anti-clockwise by modifying the pose to <pose>0 0 0 0 0 1.570796</pose>, now the x axis ends pointing West, y axis pointing to the North and the magnetic field should read

magnetic_field:
  x: 0.031671393662691116
  y: 0.17961739003658295
  z: -0.12302243709564209

• Actual behavior: It seems that the Magnetometer system rotates in the opposite way, making the x, y and z readings not accurate. When I rotate the model 90° anti-clockwise in Gazebo, setting the pose to <pose>0 0 0 0 0 1.570796</pose>, the magnetic field measurements I get are

magnetic_field:
  x: -0.031671334964643014
  y: -0.1796174003866232
  z: -0.12302243709564209

Which correspond to a rotation of -90°. I think that the rotation angle in Gazebo reference frame should be transformed from ENU to NED before using it for the magnetic field calculation.

Steps to reproduce

1. Create a ROS workspace
2. Download the test code from magnetometer_demos into the src folder of the workspace
3. Run ros2 launch magnetometer_demos magnetometer.launch.py
4. Edit simple_mag.world on lines 92 to 95. Leave one of them without any comments
5. Run colcon build to update the workspace
6. Check the magnetometer topic

gz topic -e -t /magnetometer
ros2 topic echo /magnetometer

Please let me know if you need any modification to the provided code of if I am missing something.