EDIT2: I have forked the gazebo_ros_demos package to try a velocity control on the rrbot simple robot.

Here is the link to my repo: https://github.com/Arn-O/gazeborosdemos.git

I have changed something in the configuration files.

VelocityJointInterface and no longer EffortJointInterface:

  <transmission name="tran2">
    <type>transmission_interface/SimpleTransmission</type>
    <joint name="joint2"/>
    <actuator name="motor2">
      <hardwareInterface>VelocityJointInterface</hardwareInterface>
      <mechanicalReduction>1</mechanicalReduction>
    </actuator>
  </transmission>

\velocitycontrollers and no longer \effortcontrollers:

rrbot:
  joint1_position_controller:
    type: effort_controllers/JointPositionController
    joint: joint1
    pid: {p: 100.0, i: 0.01, d: 10.0}
  joint2_velocity_controller:
    type: velocity_controllers/JointVelocityController
    joint: joint2
    pid: {p: 100.0, i: 0.01, d: 10.0}

The robot does not explode with this configuration, but I do not have the expected effect. The joint2 is not animated.

EDIT: this is related to the velocity controller. I had another issue before the upgrade, see answer.

Hello.

I have upgraded the source code of the package required for the installation of Gazebo 1.9 and ROS, and now my robot blows up when I launch the controllers. (EDIT: it is fine without the velocity controllers).

Before the controllers:

After:

It looks like everything has collapsed to the origin point of my robot, like if there were no joints.

It was working fine before the update (expect the velocity controller). (EDIT: I had the usse described in the following answer).

Any idea?

Thx in advance!

EDIT: additional details.

Here is the definition of the elements of my robot related to this topic.

...
<joint name="wheel_joint_fl" type="continuous">
  <axis xyz="0 1 0"/>
  <limit effort="${wheel_joint_effort}" velocity="${wheel_joint_velocity}"/>
  <origin xyz="${wheel_offset_x} ${wheel_offset_y} ${wheel_offset_z}" rpy="0 0 0"/>
  <parent link="caster_link_fl"/>
  <dynamics damping="${wheel_joint_damping}" friction="${wheel_joint_friction}"/>
  <safety_controller k_velocity="${wheel_joint_safety_k_velocity}"/>
  <child link="wheel_link_fl"/>
</joint>
...

Definition of the transmission:

...
<transmission name="wheel_trans_fl">
  <type>transmission_interface/SimpleTransmission</type>
  <joint name="wheel_joint_fl"/>
  <actuator name="wheel_motor_fl">
    <hardwareInterface>EffortJointInterface</hardwareInterface>
    <mechanicalReduction>${wheel_mechanical_reduction}</mechanicalReduction>
  </actuator>
</transmission>
...

Launch file for the controllers:

...  
<node name="controller_spawner" pkg="controller_manager"
    type="spawner" respawn="false" output="screen"
    ns="/youbot" args="--namespace=/youbot
        wheel_joint_fl_velocity_controller
        wheel_joint_fr_velocity_controller
        wheel_joint_bl_velocity_controller
        wheel_joint_br_velocity_controller
        caster_joint_fl_position_controller
        caster_joint_fr_position_controller
        caster_joint_bl_position_controller
        caster_joint_br_position_controller
        arm_joint_1_position_controller
        arm_joint_2_position_controller
        arm_joint_3_position_controller
        arm_joint_4_position_controller
        arm_joint_5_position_controller
        gripper_finger_joint_l_position_controller
        gripper_finger_joint_r_position_controller" />

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

And parameters of the controllers:

youbot:
  wheel_joint_fl_velocity_controller:
    type: effort_controllers/JointVelocityController
    joint:  wheel_joint_fl
    pid: {p: 100.0, i: 0.01, d: 10.0}
  wheel_joint_fr_velocity_controller:
    type: effort_controllers/JointVelocityController
    joint:  wheel_joint_fr
    pid: {p: 100.0, i: 0.01, d: 10.0}
  wheel_joint_bl_velocity_controller:
    type: effort_controllers/JointVelocityController
    joint:  wheel_joint_bl
    pid: {p: 100.0, i: 0.01, d: 10.0}
  wheel_joint_br_velocity_controller:
    type: effort_controllers/JointVelocityController
    joint:  wheel_joint_br
    pid: {p: 100.0, i: 0.01, d: 10.0}
    ...

I have no error message when the bug is triggered. I do not know if there is a useful log somewhere.

I can create a simple rrbot like with a velocity controller to investigate the point (the tutorial has been very helpful).