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I try to follow a tutorial in the "Programming Robots with ROS" book. In this tutorial I want to show and move my own robot model in Gazebo. The URDF description loads correctly in Gazebo, the model is shown. Then I extended the URDF by dynamics and ros_control. When I launch the configuration, there are errors from gazebo_ros_control, that my controller could not be loaded.

controller type 'position_controllers/JointTrajectoryController' does not exist.
In the Doc of JointTrajectoryController http://wiki.ros.org/joint_trajectory_controller in the minimal description, position interface is written, that
type: "position_controllers/JointTrajectoryController"
should be used.

In my case this leads to the above error.

My controller definition:

arm_controller:
type: "position_controllers/JointTrajectoryController"
joints:
- hip
- shoulder
- elbow
- wrist

rosservice call controller_manager/list_controller_types
types: 
  - diff_drive_controller/DiffDriveController
  - joint_state_controller/JointStateController
  - position_controllers/JointGroupPositionController
  - position_controllers/JointPositionController
base_classes: 
  - controller_interface::ControllerBase
  - controller_interface::ControllerBase
  - controller_interface::ControllerBase
  - controller_interface::ControllerBase 

There it shows position_controllers only with JointPositionController. In this case my arm_controller is not found.


My Environment:

  • Ubuntu focal

  • ROS - noetic

    Which is the correct way to follow, to bring my robot to life? rostopic list should show my arm_controller. But it is not loaded.


Originally posted by GUENNI on ROS Answers with karma: 56 on 2020-06-14

Post score: 1


Original comments

Comment by GUENNI on 2020-06-15:
Think I got it to work. I changed JointTrajectoryController to JointGroupPositionController. /arm_controller is now loaded and a topic /arm_controller/command is visible. Now I must see, how I can get functionality of the JointTrajectoryController.

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1 Answer 1

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Thank you xibeisiber. Your answer helped me. Only I had to install ros-noetic-joint-trajectory-controller. This one was not automatically installed.


Originally posted by GUENNI with karma: 56 on 2020-06-15

This answer was ACCEPTED on the original site

Post score: 1

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