How to use the gmapping SLAM Algorithm correctly?

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Hello everyone,

I am using gmapping to map my environment in RVIZ. Herefore I am using two sensors - one on the front left side and the other on the rear right side - for my mobile robot. The problem is that the mapping starts from the center of the mobile robot and not from the specified sensors, although the sensor data are merged correctly. Do you have any idea to fix the problem?

After loading my mobile robot in gazebo. I am launching the following launch.file to use the gmapping slam algoritm:

<launch>
  <arg name="slam_methods" default="gmapping" doc="slam type [gmapping, cartographer, hector, karto, frontier_exploration]"/>
  <arg name="configuration_basename" default="robot_lds_2d_gazebo.lua"/>
  <arg name="open_rviz" default="true"/>

  <!-- SLAM: Gmapping, Cartographer, Hector, Karto, Frontier_exploration, RTAB-Map -->
   <include file="$(find robot_slam)/launch/robot_$(arg slam_methods).launch">
    <arg name="configuration_basename" value="$(arg configuration_basename)"/>
  </include> 

  <!-- rviz -->
  <group if="$(arg open_rviz)">
    <node pkg="rviz" type="rviz" name="rviz" required="true"
          args="-d $(find robot_slam)/rviz/robot_gmapping.rviz">
    </node>
  </group>
</launch>

the robot_lds_2d_gazebo.lua configuration file:

include "map_builder.lua"
include "trajectory_builder.lua"

options = {
  map_builder = MAP_BUILDER,
  trajectory_builder = TRAJECTORY_BUILDER,
  map_frame = "map",
  tracking_frame = "base_footprint",
  published_frame = "base_link",
  odom_frame = "odom",
  provide_odom_frame = false,
  publish_frame_projected_to_2d = false,
  use_odometry = true,
  use_nav_sat = false,
  use_landmarks = false,
  num_laser_scans = 2,
  num_multi_echo_laser_scans = 0,
  num_subdivisions_per_laser_scan = 1,
  num_point_clouds = 0,
  lookup_transform_timeout_sec = 0.2,
  submap_publish_period_sec = 0.3,
  pose_publish_period_sec = 5e-3,
  trajectory_publish_period_sec = 30e-3,
  rangefinder_sampling_ratio = 1.,
  odometry_sampling_ratio = 1.,
  fixed_frame_pose_sampling_ratio = 1.,
  imu_sampling_ratio = 1.,
  landmarks_sampling_ratio = 1.,
}


MAP_BUILDER.use_trajectory_builder_2d = true
TRAJECTORY_BUILDER_2D.min_range = 0.1
TRAJECTORY_BUILDER_2D.max_range = 10.0
TRAJECTORY_BUILDER_2D.missing_data_ray_length = 3.
TRAJECTORY_BUILDER_2D.use_imu_data = true
TRAJECTORY_BUILDER_2D.use_online_correlative_scan_matching = true
TRAJECTORY_BUILDER_2D.motion_filter.max_angle_radians = math.rad(0.1)

POSE_GRAPH.constraint_builder.min_score = 0.65
POSE_GRAPH.constraint_builder.global_localization_min_score = 0.7

return options

my robot_gmapping.launch file:

<launch>
  <!-- Arguments -->
  <arg name="set_base_frame" default="base_link"/>
  <arg name="set_odom_frame" default="odom"/>
  <arg name="set_map_frame"  default="map"/>

  <!-- Gmapping -->
  <node pkg="gmapping" type="slam_gmapping" name="robot_slam_gmapping" output="screen">
    <param name="base_frame" value="$(arg set_base_frame)"/>
    <param name="odom_frame" value="$(arg set_odom_frame)"/>
    <param name="map_frame"  value="$(arg set_map_frame)"/>
    <rosparam command="load" file="$(find robot_slam)/config/gmapping_params.yaml" />
  </node>
</launch>

gmapping_params.yaml:

map_update_interval: 2.0
maxUrange: 10.0
sigma: 0.05
kernelSize: 1
lstep: 0.05
astep: 0.05
iterations: 5
lsigma: 0.075
ogain: 3.0
lskip: 0
minimumScore: 50
srr: 0.1
srt: 0.2
str: 0.1
stt: 0.2
linearUpdate: 1.0
angularUpdate: 0.2
temporalUpdate: 0.5
resampleThreshold: 0.5
particles: 100
xmin: -10.0
ymin: -10.0
xmax: 10.0
ymax: 10.0
delta: 0.05
llsamplerange: 0.01
llsamplestep: 0.01
lasamplerange: 0.005
lasamplestep: 0.005

Thanks in advance! I appreciate your help!