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septentrio-gnss / septentrio_gnss_driver

ROS 1 & 2 driver for Septentrio GNSS & INS receivers
BSD 3-Clause "New" or "Revised" License
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Angular velocities on topic `/twist_ins` all zero #105

Open abaeyens-imod opened 8 months ago

abaeyens-imod commented 8 months ago

Issue description

The angular velocities published on the topic /twist_ins are all zeros even when the platform is rotating and angular velocities are being published on the the /imu topic.

Nodes that currently want to observe both angular and linear velocity have to subscribe to two topics (/twist_ins and /imu) instead of only /twist_ins.

Steps to reproduce the issue

  1. Setup Septentrio hardware and launch Septentrio ROS node.
  2. Look at the values of /twist_ins/twist/twist/angular/x.

What's the expected result?

The angular velocities in the geometry_msgs/msg/TwistWithCovarianceStamped message are the best available estimates for the platform's angular velocity. This can be just the gyro measurements, like published on /imu, though preferably these measurements are already corrected (e.g. bias correction). They are expressed in the frame stated in the frame_id of this message.

What's the actual result?

They are always zero.

Additional details / screenshot

Graph created while moving around, time axis on the horizontal: image

Version

Compiled septentro_gnss_driver from source, branch ros2, HEAD commit 207c37bc.

Thank you in advance for your time. In case there's any setting we missed, or more information is required, please share.

thomasemter commented 8 months ago

The SBi does not report the bias corrected or estimated angular velocities. We would have to use raw IMU measurements what I would rather not do, since they might be misleading due to their bias. It is always possible to pull these from the /imu message.