rotational offset between odometry/gps and odometry/filtered

[oskarmue]

Hi, for the odometry/filtered I use the ekf_node in order to fuse a lidar_odometry source and imu data. Then I use odometry/filtered together with the imu/data for the navsat_transform node. It all seems to work fine, except that the Position from odometry/gps seems to have a roational offset from the Position calculated from lidar and imu (see image below, white is odometry/gps and red is odometry/filtered). Are there certain parameters in order to correct that? (they are both in the same odom frame)

`

this is my param file

` ekf_filter_node: ros__parameters: frequency: 30.0 sensor_timeout: 2.0 two_d_mode: false transform_time_offset: 0.0 transform_timeout: 0.0 print_diagnostics: true debug: false

map_frame: map
odom_frame: odom
base_link_frame: base_link
world_frame: odom

odom0: /lidarslam_odometry
odom0_config: [true, true, true,
              false, false, false,
              false, false, false,
              false, false, false,
              false, false, false]
odom0_queue_size: 10
odom0_differential: false
odom0_relative: true

imu0: imu/data
imu0_config: [false, false, false,
              true,  true,  true,
              false, false, false,
              true,  true,  true,
              true,  true,  true]

imu0_nodelay: false
imu0_differential: false
imu0_relative: true
imu0_queue_size: 5
imu0_pose_rejection_threshold: 0.8                 # Note the difference in parameter names
imu0_twist_rejection_threshold: 0.8                #
imu0_linear_acceleration_rejection_threshold: 0.8  #

imu0_remove_gravitational_acceleration: true

use_control: false

navsat_node: ros__parameters: frequency: 30.0 delay: 3.0 magnetic_declination_radians: 0.058 #0.04256444
yaw_offset: 0.0 zero_altitude: false broadcast_cartesian_transform: false

broadcast_utm_transform_as_parent_frame: false

publish_filtered_gps: false
use_odometry_yaw: false
wait_for_datum: false`

[oskarmue]

Could the reason for that be a magnetic field, that is influencing the imu and therefore the direction of the east is not measured correctly?

[ayrton04]

Thanks for the question. However, all questions should be directed to answers.ros.org or robotics.stackexchange.com.