QUIZ - my Gurdy always fall

Course Support URDF for Robot Modeling
1

Hello everyone,

I am working on the Quiz trying to spawn the Gurdy robot. I have followed the class and done the my_mira_description package successfully, but I am not being able to understand what am I missing in order to spawn Gurdy, when it appears in the gazebo simulation it falls apart. I have even tried with the original gurdy.urdf file, in gurdy_description package, but the same happens.

Here you can find my code:

As asked in the quiz, the main launch file is spawn_gurdy.launch

2

Are you publishing the tf? Are the controllers running?

3

I think I am, somewhere within the spawn_gurdy.launch, I call gurdy_control.launch which is the following launch file:

<launch>
    <!-- Load joint controller configurations from YAML file to parameter server -->
    <rosparam file="$(find my_gurdy_description)/config/gurdy_controller.yaml" 
                command="load"/>

    <node name="controller_spawner" 
            pkg="controller_manager" 
            type="spawner" 
            respawn="false"
            output="screen" 
            ns="/gurdy" 
            args="head_upperlegM1_joint_position_controller 
                head_upperlegM2_joint_position_controller 
                head_upperlegM3_joint_position_controller 
                upperlegM1_lowerlegM1_joint_position_controller 
                upperlegM2_lowerlegM2_joint_position_controller 
                upperlegM3_lowerlegM3_joint_position_controller 
                joint_state_controller --shutdown-timeout 3"/>

    <node name="robot_state_publisher" 
            pkg="robot_state_publisher" 
            type="robot_state_publisher"
            respawn="false" 
            output="screen">
        <remap from="/joint_states" to="/gurdy/joint_states" />
    </node>

</launch>

When I do rostopic list I see only the following related to gurdy:
/gurdy/imu/data
/gurdy/joint_states

So I guess the controllers might be missing? Yet I am not really understanding why, I have double checked the gurdy_controller.yaml file

5

can you check whether tf and joint_states are properly published? Do you get values there?

Also you might wanna try pausing the simulation first, then spawning it.

6

No, I do not get any values either in tf or joint_states.

7

I did some changes to reorganize my repository, now the code is here:

8

Hi @soffx27,
I dove deep into it and eventually figured it out. The issue lies with the namespace. I got it to work by removing it, how to properly add it, you gonna have to figure out, but this is at least a working startingpoint.

new gurdy_control.launch

<?xml version="1.0" encoding="UTF-8"?>
<launch>
    <!-- Load joint controller configurations from YAML file to parameter server -->
    <rosparam file="$(find my_gurdy_description)/config/gurdy_controller.yaml" command="load" />

    <!-- load the controllers -->

    <node name="controller_spawner" 
            pkg="controller_manager" 
            type="spawner" 
            respawn="false"
            output="screen"
            args="head_upperlegM1_joint_position_controller 
            head_upperlegM2_joint_position_controller 
            head_upperlegM3_joint_position_controller 
            upperlegM1_lowerlegM1_joint_position_controller 
            upperlegM2_lowerlegM2_joint_position_controller 
            upperlegM3_lowerlegM3_joint_position_controller 
            joint_state_controller --shutdown-timeout 3"/>

    <!-- convert joint states to TF transforms for rviz, etc -->
    <node name="robot_state_publisher" 
            pkg="robot_state_publisher" 
            type="robot_state_publisher"
            respawn="false" 
            output="screen">
    </node>
</launch>

new gurdy_controller.yaml

joint_state_controller:
  type: joint_state_controller/JointStateController
  publish_rate: 50

# Position Controllers ---------------------------------------
head_upperlegM1_joint_position_controller:
  type: effort_controllers/JointPositionController
  joint: head_upperlegM1_joint
  pid: {p: 3.0, i: 1.0, d: 0.0}

head_upperlegM2_joint_position_controller:
  type: effort_controllers/JointPositionController
  joint: head_upperlegM2_joint
  pid: {p: 3.0, i: 1.0, d: 0.0}

head_upperlegM3_joint_position_controller:
  type: effort_controllers/JointPositionController
  joint: head_upperlegM3_joint
  pid: {p: 3.0, i: 1.0, d: 0.0}

upperlegM1_lowerlegM1_joint_position_controller:
  type: effort_controllers/JointPositionController
  joint: upperlegM1_lowerlegM1_joint
  pid: {p: 3.0, i: 1.0, d: 0.0}

upperlegM2_lowerlegM2_joint_position_controller:
  type: effort_controllers/JointPositionController
  joint: upperlegM2_lowerlegM2_joint
  pid: {p: 3.0, i: 1.0, d: 0.0}

upperlegM3_lowerlegM3_joint_position_controller:
  type: effort_controllers/JointPositionController
  joint: upperlegM3_lowerlegM3_joint
  pid: {p: 3.0, i: 1.0, d: 0.0}
9

Simon, hi,

Thank you very much! It works that way…
Now I’ll try to figure out why the ns is wrong.

Best regards

1 Like