Robot_localization configuration (GPS, IMU, Odometry)

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Hello,

I try to use the robot_localization package for a project where we have the following sensors:

• IMU

• Odometry by wheel encoders

• GPS

After I have read the robot_localization documentation and seen the ROSCON presentation of Tom Moore I have the following setup:

• ekf localization node with input of navsat_transform_node (odometry/gps), IMU and odom

• navsat_transform node with input from ekf localization node (odometry/filtered) and IMU

My frame configuration is the following:

• odom_frame: odom

• base_link_frame: base_link

• world_frame: odom

I have read in the "ekf_template.yaml" of the robot_localization package that I should set the world_frame to map when fusing a global absolute position and get the odom->base_link transform from somewhere else (another estimation node for example but I shouldn't fuse global data there).

In my configuration I am using the global position in both nodes (input for navsat_transform_node and the output of the node into ekf_localization_node)

Do I need to create a second ekf_localization_node with just continous data input and use the data output of this node as input into the first ekf_localization_node which just fuses two odometry sources (from navsat_transform_node and second ekf_localization_node) then?

Is the output of the first ekf_localization_node or the navsat_transform_node the most reliable then to use the pose for distance measuring or calculation of circle radius for example?

Thank you guys in advance!

EDIT:

We have the following configuration for ekf_localization_node (at the moment):

frequency: 30

sensor_timeout: 0.1

two_d_mode: false

transform_time_offset: 0.0

transform_timeout: 0.0

print_diagnostics: true

debug: false

debug_out_file: robot_localization_debug.txt

publish_tf: true

publish_acceleration: false

odom_frame: odom            # Defaults to "odom" if unspecified
base_link_frame: base_link  # Defaults to "base_link" if unspecified
world_frame: odom           # Defaults to the value of odom_frame if unspecified

odom0: /odom

odom0_config: [false,  false,  false,
               false, false, false,
               true, true, false,
               false, false, true,
               false, false, false]

odom0_queue_size: 2

odom0_nodelay: false

odom0_differential: false

odom0_relative: false

odom0_pose_rejection_threshold: 5
odom0_twist_rejection_threshold: 1

odom1: /odometry/gps
odom1_config: [true, true, true,
               false, false, false,
               false, false, false,
               false, false, false,
               false, false, false]

odom1_differential: false

odom1_relative: true

odom1_queue_size: 2

odom1_pose_rejection_threshold: 2

odom1_twist_rejection_threshold: 0.2

odom1_nodelay: false


imu0: /imu/data
imu0_config: [false, false, false,
              false,  false, true,
              false, false, false,
              false, false, true,
              true, false, false]
imu0_nodelay: false

imu0_differential: false

imu0_relative: true

imu0_queue_size: 5

imu0_pose_rejection_threshold: 0.8               

imu0_twist_rejection_threshold: 0.8

imu0_linear_acceleration_rejection_threshold: 0.8  

imu0_remove_gravitational_acceleration: true

use_control: false

stamped_control: false

control_timeout: 0.2

control_config: [true, false, false, false, false, true]

acceleration_limits: [1.3, 0.0, 0.0, 0.0, 0.0, 3.4]

deceleration_limits: [1.3, 0.0, 0.0, 0.0, 0.0, 4.5]

acceleration_gains: [0.8, 0.0, 0.0, 0.0, 0.0, 0.9]

deceleration_gains: [1.0, 0.0, 0.0, 0.0, 0.0, 1.0]

process_noise_covariance: [0.05, 0,    0,    0,    0,    0,    0,     0,     0,    0,    0,    0,    0,    0,    0,
                           0,    0.05, 0,    0,    0,    0,    0,     0,     0,    0,    0,    0,    0,    0,    0,
                           0,    0,    0.06, 0,    0,    0,    0,     0,     0,    0,    0,    0,    0,    0,    0,
                           0,    0,    0,    0.03 ...