I’m developing a ROS2 node that reads GPS and IMU data from a file and publishes it using various ROS2 topics (e.g., sensor_msgs::msg::NavSatFix, geometry_msgs::msg::PoseWithCovarianceStamped, and sensor_msgs::msg::Imu). The node works correctly when it first starts: the data seems accurate, and the pose behaves as expected. However, after a few seconds, the published data begins to drift out of bounds, and the system starts displaying incorrect positions.

Problem Description:

Expected Behavior: The GPS and pose data should remain accurate and within the expected area throughout the runtime.
Actual Behavior: Initially, the object/vehicle is correctly positioned and appears to turn around as expected. After a few seconds, the position data starts to drift, and the object/vehicle eventually moves outside the expected bounds.
Environment: ROS2, using a combination of GPS and IMU data for navigation and localization.

Code Overview:
Below is a simplified version of my node. The full node reads from a file, converts latitude/longitude to UTM coordinates, and publishes GPS, pose, and IMU data to the respective topics.

Troubleshooting Attempted:

Time Synchronization: Ensured the time difference (time – last_time) and the ROS time are correctly calculated.

Loop Delays: Checked the loop’s processing time and reduced the sleep duration to avoid timing issues.

Coordinate Conversion: Verified that the UTM conversion is accurate and that the local coordinates are calculated relative to a correct origin.

Covariance Settings: Reviewed the covariance values to ensure they accurately represent sensor uncertainties.

Specific Questions:

• Why does the system appear to function correctly at the beginning but starts drifting out of bounds after a few seconds?
• Could there be a cumulative timing or precision error in my loop that’s causing this drift? How can I mitigate it?
• What are some best practices to ensure the GPS and pose data remain accurate over time when processing and publishing data in a loop like this?

Additional Context:

• The problem seems to be time-related, as the drift occurs gradually after the node has been running for a few seconds.
• I’m using standard ROS2 tools and libraries, with the GPS data being simulated from a pre-recorded dataset.
• Any insights or suggestions on how to debug or resolve this issue would be greatly appreciated!