msunardi/timmy2-gazebo-ros

Robot model for gazebo and ROS control

Timmy2 Gazebo ROS

A set of ROS packages for simulating the Timmy2 robot (based on HROS-1 robot) in Gazebo and Rviz.

There are two ROS packages in this project: timmy2_description and timmy2_control.

timmy2_description

This package mainly contains the model of Timmy2 written in URDF/Xacro format.

The 3D meshes of Timmy2 were made using Blender 2.79 and exported to .dae (Collada) format.

The current model of Timmy2 is described in the urdf/timmy3.urd.xacro file, and uses the meshes located in the meshes2/ directory.

Fig. 1: Timmy2 in Gazebo

Fig. 2: Timmy2 in Rviz

Fig. 3: Timmy2 in Rviz with Joint State Publisher GUI

Current state/issues

• To run all (Gazebo, Rviz, Joint State Publisher) run:

  $ roslaunch timmy2_description timmy_description.launch

  This will load the timmy3.urdf.xacro model and launch Gazebo. Additionally, it will launch (i.e. <include ...> the timmy2_control/timmy2_control.launch file (see details below)

• The current Timmy2 model has a twist DOF at the elbow. The original HROS-1-based model does not have this DOF. Use the timmy2.urdf.xacro in the launch file for this original model.

  <!--timmy_description.launch-->
  ...
  <arg name="model" default="$(find timmy2_description)/urdf/timmy2.urdf.xacro"/>
  ...

• Cannot use both the joint_state_publisher and Gazebo simulation. When Gazebo is running, robot_state_publisher which connects Gazebo to ROS will continuously publish a stream of output of the physics simulation in Gazebo to /timmy2/joint_state topic (JointState type) which will override any values published by joint_state_publisher.

  The effects of joint_state_publisher can be seen briefly in Rviz, but will quickly revert to the state reflected in Gazebo.

  joint_state_publisher currently has no effect to the model in Gazebo.

• The model can be moved using two other methods: directly publishing to a joint topic from the Terminal or using rqt_gui (see below)

• Currently, it's best to choose either: a) use Gazebo and move the model using direct topic publishing or rqt_gui OR b) use only joint_state_publisher and disconnect Gazebo simulation. See below for instructions/commands.

timmy2_control

This package contains configurations for/to:

• spawn joint controllers (from controller_manager package)

  • This is used to connect ROS with Gazebo (i.e. so publishing joint position from ROS will be reflected in Gazebo, and vice versa)

• launch joint_state_publisher

  • This is for manual control of each joint via slider bars (GUI).

• launch robot_state_publisher

  • From Gazebo tutorial

  ...listens to /joint_states messages from the joint_state_controller then publishes the transforms to /tf. This allows you to see your simulated robot in Rviz as well as do other tasks.

• launch Rviz

Instructions/How-To's

Launch everything

$ roslaunch timmy2_description timmy_description.launch

NOTE: The current configuration tries to make joint_state_publisher and Gazebo work at the same time. This is achieved by commenting the remap argument for robot_state_publisher in timmy2_control/launch/timmy2_control.launch

<!-- Joint state publisher GUI -->
<param name="use_gui" value="${arg gui}"/>
<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher">
    <rosparam param="source_list">["timmy2/joint_states"]</rosparam>
</node>

<!-- 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">
    <!--remap from="/joint_states" to="/timmy2/joint_states" /-->
</node>

Turn off Gazebo and Use joint_state_publisher GUI

1. Comment the rosparam line for joint_state_publisher in timmy2_control/launch/timmy2_control.launch

<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher">
   <!--rosparam param="source_list">["timmy2/joint_states"]</rosparam-->
</node>

2. Launch everything (see above)

Only Use Gazebo as Control

WARNING: joint_state_publisher will not work.

1. Uncomment rospoaram line for joint_state_publisher and remap for robot_state_publisher in timmy2_control/launch/timmy2_control.launch

   <!-- Joint state publisher GUI -->
   <param name="use_gui" value="${arg gui}"/>
   <node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher">
       <rosparam param="source_list">["timmy2/joint_states"]</rosparam>
   </node>
   
   <!-- 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">
       <remap from="/joint_states" to="/timmy2/joint_states" />
   </node>

2. Launch everything (see above)

Publish Joint Positions

1. Launch everything

   $ roslaunch timmy2_description timmy_description.launch
   

2. In a new Terminal

   $ rostopic pub -1 /timmy2/right_elbow_position_controller/command std_msgs/Float64 "data: 1.5"

   Change right_elbow_position_controller to any other joint topics i.e. <joint_name>_position_controller/command and give data some value (Float64, in radians).

Move Model using rqt_gui

1. Launch everything

   $ roslaunch timmy2_description timmy_description.launch
   

2. In a new Terminal

   $ rosrun rqt_gui rqt_gui
   

3. Open a Message Publisher panel

4. Press the green PLUS button to add a new message to publish

5. Click the checkbox to make the message active

6. Choose the topic to publish to e.g. /timmy2/right_elbow_position_controller/command

7. Make sure the type is correct: std_msgs/Float64

8. Choose a rate to publish the message (50 or 100Hz is good)

9. In the Expressions field, enter a value or a math expression.

• i is the default variable of time.
• Cyclic expressions using sin or cos will create cyclic motions. e.g. 1.5*sin(i*100)
• Expressions are assumed to follow Python expressions (i.e. as if you were to write the expression in Python). See Fig 4 below.

Fig. 4: Moving Timmy2 model using rqt_gui