EPMC Sample Bot

This is a minimal sample robot for testing and learning how to use the EPMC module to setup base control for a mobile robot.

Feel free to adopt it in building your own mobile base control with ROS2

Working with the Hardware

Note

You can test this on RaspberryPi or a devPC

Prerequisite Dependencies

• install the libserial-dev package on the Raspberry Pi 4b machine or on your Dev PC

  sudo apt-get update
  sudo apt install libserial-dev

Create ROS Workspace And Download the packages

• create your ROS Workspace in the home directory

• download and setup the epmc_hardware_interface ros2 package (if you don't have it)

  cd ~/<your-ros-ws>/src
  git clone https://github.com/robocre8/epmc_hardware_interface.git

• cd into the src folder of your ROS Workspace and download the demo_bot packages

  cd ~/<your-ros-ws>/src
  git clone https://github.com/robocre8/epmc_sample_bot.git

• cd into the root directory of your ROS Workspace and run rosdep to install all necessary ros package dependencies

  cd ~/<your-ros-ws>/
  rosdep install --from-paths src --ignore-src -r -y

• build your ROS Workspace

  cd ~/<your-ros-ws>/
  colcon build --symlink-install

  OR

  cd ~/<your-ros-ws>/
  colcon build --symlink-install --parallel-workers 2

Check EPMC USB PORT Values (You can skip this if you already know how to do this)

• check the serial port the connected sensors and motor controller

  The best way to select the right serial port (if you are using multiple serial device) is to select by path

  ls /dev/ttyA*

• go to the epmc_sample_bot_description/urdf/ros2_control.xacro file and change the port parameter to the port value gotten

• you can also edit other parameters like the command_interface min and max velocity parameter, etc.

view robot

• View robot

  source ~/<your-ros-ws>/install/setup.bash
  ros2 launch epmc_sample_bot_description rsp.launch.py use_joint_state_pub:=true

• on Your dev-PC, open rviz2 in a differnt terminal to vizualize the robot

Run Robot

• Open a new terminal and start the epmc_sample_bot_base

  source ~/<your-ros-ws>/install/setup.bash
  ros2 launch epmc_sample_bot_base robot.launch.py

Note

If any error occurs, unplug the USB HUB from the Raspberry Pi Port and plug it back. Everything should now work.

• on Your dev-PC, open rviz2 in a differnt terminal to vizualize the robot

• control the robot via teleop

Note

your teleop should publish Stamped velocity on the /cmd_vel topic

• you can use the arrow_key_teleop_drive package