Please ask about problems and questions regarding this tutorial on answers.ros.org. Don't forget to include in your question the link to this page, the versions of your OS & ROS, and also add appropriate tags.

Running a realtime Cartesian controller

Introduction

In this tutorial we will run the controller created in the previous tutorial. This tutorial uses the gazebo simulator environment to run the controller, so you'll need some knowledge of gazebo. If you have never heard about gazebo, check out this tutorial first.

Starting the pr2 in Gazebo

So, let's get gazebo running first:

  $ rosmake pr2_gazebo
  $ roslaunch gazebo_worlds empty_world.launch

You should see an empty gazebo world.

Now let's create a pr2 robot inside this world:

  $ roslaunch pr2_gazebo pr2.launch

And your simulation world should look like this.

Configuring the Controller

The first step to running a controller is laying out its configuration on the parameter server. As explained in the tutorial about running a joint space controller, we can create a yaml file to do this. Create a file called cart_controller.yaml:

  my_tutorial_controller_cart:
    type: MyControllerCart
    root_name: torso_lift_link
    tip_name: r_gripper_tool_frame

And also create a launch file for this controller, in a file called my_controller_cart.launch:

<launch>
   <rosparam file="$(find my_controller_cart_pkg)/cart_controller.yaml" command="load" />

   <node pkg="pr2_controller_manager" type="spawner" args="my_tutorial_controller_cart" name="my_controller_cart_spawner" />
</launch>

Running the Controller

Before moving on we need to check if our controller got registered to the controller manager. To get the list of registered controllers, type:

  $ rosrun pr2_controller_manager pr2_controller_manager list-types

Look in the output for our controller MyControllerCart. If it's there you're ready to load and start it.

Running

If everything looks good, let's try to run our controller:

  $ roslaunch my_controller_cart.launch

You should see: "Loaded my_tutorial_controller". We can confirm that the controller is loaded with :

  $ rosrun pr2_controller_manager pr2_controller_manager list

The right arm of the pr2 should start moving in a pretty nice Cartesian circle!