Welcome to MicroROS Robot repository

Robot state estimation

Note: The virtual machine needs to be in the same LAN as the car, and the ROS_DOMAIN_ID needs to be consistent. You can check [Must read before use] to set the IP and ROS_DOMAIN_ID on the board.

1、Program function description

After the program is started, it will subscribe to imu and odom data, filter out part of the imu data, and then fuse it with the odom data. Finally, a fused odom data will be output to estimate the status of the robot. This data is mostly used in mapping and navigation. .

2、Start and connect to the agent

Taking the supporting virtual machine as an example, enter the following command to start the agent:

sudo docker run -it --rm -v /dev:/dev -v /dev/shm:/dev/shm --privileged --net=host microros/micro-ros-agent:humble udp4 --port 8090 -v4

Then, turn on the car switch and wait for the car to connect to the agent. The connection is successful, as shown in the figure below.

3、starting program

Terminal input，

xxxxxxxxxx
ros2 launch yahboomcar_bringup yahboomcar_bringup_launch.py

Enter the following command to view the communication diagram between nodes，

xxxxxxxxxx
ros2 run rqt_graph rqt_graph

If it is not displayed at first, select [Nodes/Topics(all)], and then click the refresh button in the upper left corner.

The fused node is /ekf_filter_node. You can query the relevant information of this node and input it through the terminal.

xxxxxxxxxx
ros2 node info /ekf_filter_node

Combined with the node communication diagram above, it can be seen that the node subscribes to /imu/data and /odom_raw data, and then publishes a /odom data.

4、Parse launch file

launch file location (taking the supporting virtual machine as an example):

xxxxxxxxxx
/home/yahboom/yahboomcar_ws/src/yahboomcar_bringup/launch

yahboomcar_bringup_launch.py

​x
from ament_index_python.packages import get_package_share_path

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch.conditions import IfCondition, UnlessCondition
from launch.substitutions import Command, LaunchConfiguration

from launch_ros.actions import Node
from launch_ros.parameter_descriptions import ParameterValue

import os
from ament_index_python.packages import get_package_share_directory

from launch.actions import IncludeLaunchDescription
from launch.launch_description_sources import PythonLaunchDescriptionSource

print("---------------------robot_type = x3---------------------")
def generate_launch_description():
    imu_filter_config = os.path.join(              
        get_package_share_directory('yahboomcar_bringup'),
        'param',
        'imu_filter_param.yaml'
    ) 

    imu_filter_node = IncludeLaunchDescription(
        PythonLaunchDescriptionSource([os.path.join(
            get_package_share_directory('imu_filter_madgwick'), 'launch'),
            '/imu_filter.launch.py'])
    )
    
    ekf_node = IncludeLaunchDescription(
        PythonLaunchDescriptionSource([os.path.join(
            get_package_share_directory('robot_localization'), 'launch'),
            '/ekf.launch.py'])
    )
     
    description_launch = IncludeLaunchDescription(
        PythonLaunchDescriptionSource([os.path.join(
        get_package_share_directory('yahboomcar_description'), 'launch'),
         '/description_launch.py'])
    )   
    
    base_link_to_imu_tf_node = Node(
     package='tf2_ros',
     executable='static_transform_publisher',
     name='base_link_to_base_imu',
     arguments=['-0.002999', '-0.0030001','0.031701','0','0','0','base_link','imu_frame']
    ) 
    
    return LaunchDescription([
        imu_filter_node,
        ekf_node,
        base_link_to_imu_tf_node,
        description_launch
    ])

The launch file starts the following nodes:

• imu_filter_node：Filter imu data nodes, mainly filter some imu data;

• ekf_node：The fusion node mainly fuses odom data and filtered imu data.

• base_link_to_imu_tf_node：Release a static change, mainly to release the pose transformation of the imu module and the car.

• description_launch：Load the URDF model.