robot_localization package ros

edit

I am trying to use the robot localization package of ros to fuse the data coming from imu (on imu topic), wheel encoder (computed odometry on /odom topic) and a RTK GPS (differential gps on topic /odom_gps). The data coming from this differential gps is not lot/long coordinates. They are the relative position from the base station which is at a certain distance from the robot. Since this differential gps is giving data in the NED frame, I am publishing this data using odometry message. And all the positions and orientations are with respect to this base station frame.

Now since I have 2 odoms and 1 imu to fuse, I need 2 tf's, that is one from baselink to odom_gps and the other from baselink to odom. Only then it will be fused by the filter correctly. I am not able to do this since it gives warning/error of having 2 parents for 1 child (baselink).

Please can someone suggest the correct way to do this.

This is my config file:

#Configuation for robot odometry EKF

frequency: 30

two_d_mode: true

publish_tf: true

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


#the odom0 configuration
odom0: /odom_gps
odom0_config: [true, true, false,
 false, false, false,
 false,  false,  false,
 false, false, false,
 false, false, false] 
odom0_differential: false


#  odom1 configuration
odom1: /odom
odom1_config: [true, true, false,
 false, false, true,
 true,  true,  false,
 false, false, true,
 false, false, false]
odom1_differential: true


# imu0 configuration
imu0: /imu
imu0_config: [false, false, false,
 false, false, false,
 false,  false,  false,
 false, false, true,   #angular velocity about z
 true, false, false]  #linear accleration along x
imu0_differential: false

process_noise_covariance: [0, 0,    0,    0,    0,    0,    0,     0,     0,    0,    0,    0,    0,    0,    0,
                            0,    0, 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, 0,    0,    0,     0,     0,    0,    0,    0,    0,    0,    0,
                            0,    0,    0,    0,    0.03, 0,    0,     0,     0,    0,    0,    0,    0,    0,    0,
                            0,    0,    0,    0,    0,    1e-9, 0,     0,     0,    0,    0,    0,    0,    0,    0,
                            0,    0,    0,    0,    0,    0,    0.025, 0,     0,    0,    0,    0,    0,    0,    0,
                            0,    0,    0,    0,    0,    0,    0,     0.025, 0,    0,    0,    0,    0,    0,    0,
                            0,    0,    0,    0,    0,    0,    0,     0,     0.04, 0,    0,    0,    0,    0,    0,
                            0,    0,    0,    0,    0,    0,    0,     0,     0,    0.01, 0,    0,    0,    0,    0,
                            0,    0,    0,    0,    0,    0,    0,     0,     0,    0,    0.01, 0,    0,    0,    0,
                            0,    0,    0,    0,    0,    0,    0,     0,     0,    0,    0,    0.02, 0,    0,    0,
                            0,    0,    0,    0,    0,    0,    0,     0,     0,    0,    0,    0,    0.01, 0,    0,
                            0,    0,    0,    0,    0,    0,    0,     0,     0,    0,    0,    0,    0,    0.01, 0,
                            0,    0,    0,    0,    0,    0,    0,     0,     0 ...