Launch files

Their are 2 major launch files that we need to run:

1. bringup.launch

This launch file is configuring and launching a set of nodes for a robotic system running on ROS (Robot Operating System).

The nodes launched in this file are:

  • ydlidar_ros/X2L.launch: Launches the driver for a YDLIDAR X2L lidar sensor. (Raspberry Pi)

  • joint_state_publisher: Publishes joint states for the robot. (Master)

  • robot_state_publisher: Publishes the transform tree for the robot. (Master)

  • imu_node.py: Reads IMU data from an MPU6050 sensor. (Raspberry Pi)

  • tf_broadcaster_imu.py: Broadcasts the transform of the IMU sensor. (Master)

  • serial_node.py: Establishes a serial communication link with an ESP8266 board running the firmware for the robot. (Raspberry Pi)

  • twist_to_pwm.py: Converts twist messages into PWM signals to control the motors of the robot. (Master)

  • esp_diff_tf.py: Calculates the odometry and publishes it as a transform. (Master)

  • joy_node: Reads input from a joystick or gamepad. (Master)

  • robot_pose_ekf: Uses sensor data to estimate the pose of the robot using an Extended Kalman Filter. (Master)

  • rviz: Launches the RViz visualization tool to visualize the robot and its environment. (Master)

The launch file also sets various parameters and remaps topics to ensure that the nodes communicate correctly with each other.

Note

Before every node, we must specify the name of the machine (master or slave), and by default, it will run on the master.

2. X2L.launch

  • This is a ROS launch file that launches the ydlidar_node node from the ydlidar_ros package on a remote machine with IP address ip_of_machine and username username_of_machine(pi).

  • The launch file sets several parameters for the LIDAR sensor, such as the serial port and baudrate used to communicate with it, the frame ID to use for publishing data, and the angle and range limits of the sensor.