How to Send a Simulated Robot to Goal Locations Using ROS

16e-post-office-1

In this tutorial, I will show you how to send a simulated robot (in Gazebo) to goal locations using ROS.

Real-World Applications

This project has a number of real-world applications: 


  • Indoor and Outdoor Delivery Robots
  • Room Service Robots
  • Robot Vacuums
  • Order Fulfillment
  • Manufacturing
  • Factories

Our robot will exist in a world that contains a post office and three houses. The use case for this simulated robot would be picking up packages at a post office and delivering them to houses in a neighborhood. 

Let’s get started!

Prerequisites

Getting Started

In our Gazebo environment, we have four main goal locations we would like to send our robot.

  • 1 – House 1
  • 2 – House 2
  • 3 – House 3
  • 4 – Post Office

Open a new terminal window, and launch the robot in Gazebo.

roslaunch mobile_manipulator mobile_manipulator_gazebo.launch

Then in another terminal window, type:

roslaunch mobile_manipulator mobile_manipulator_move_base.launch

Make a note of the X and Y coordinates of each desired goal location. I use the RViz Point Publish button to accomplish this. When you click that button, you can see the coordinate values by typing the following command in a terminal:

ros topic echo /clicked_point 

I want to have an X, Y coordinate for the following four goal locations in the world.

1 = House 1 (-15.04, -7.42, 0.0)

2 = House 2 (-14.25, 20.02, 0.0)

3 = House 3 (7.35, 20.17, 0.0)

4 = Post Office (12.12, -8.41, 0.0)

You notice how I numbered the goal locations above. That was intentional. I want to be able to type a number into a terminal window and have the robot navigate to that location.

For example, if I type 4, the robot will move to the post office. If I type 2, the robot will go to house 2.

Write the Code

Now let’s write some C++.

Open a terminal window.

roscd mobile_manipulator/src
gedit send_goals.cpp

Add this code.

Save the file, and close it.

Compile the Code

Now open a new terminal window, and type the following command:

roscd mobile_manipulator
gedit CMakeLists.txt

Go to the bottom of the file.

Add the following lines.

INCLUDE_DIRECTORIES(/usr/local/lib)
LINK_DIRECTORIES(/usr/local/lib)
 
add_executable(send_goals src/send_goals.cpp)
target_link_libraries(send_goals ${catkin_LIBRARIES})
cd ~/catkin_ws/

Compile the package.

catkin_make --only-pkg-with-deps mobile_manipulator

Run the Code

Open a new terminal window, and launch the robot in Gazebo.

roslaunch mobile_manipulator mobile_manipulator_gazebo.launch

Then in another terminal window, type:

roslaunch mobile_manipulator mobile_manipulator_move_base.launch

Open another terminal to launch the send_goals node.

rosrun mobile_manipulator send_goals
16b-send-goals

Follow the prompt to send your goal to the ROS Navigation Stack.

16c-post-office
16d-post-office-goal
16e-post-office-2
16f-reached-goal

To see the node graph (which shows what ROS nodes are running to make all this magic happen), type:

rqt_graph

If the robot is having trouble reaching the goal, you can adjust the xy_goal_tolerance (in meters) and the yaw_goal_tolerance (in radians) parameters inside the base_local_planner_params.yaml file, which is located in my ~/catkin_ws/src/mobile_manipulator/param folder.

That’s it. Keep building!