Lab 2: Modelling and visualization of manipulator¶

Scope¶

This laboratory consist of three parts:

• A short introduction.
• Reading and following URDF tutorials: http://wiki.ros.org/urdf/Tutorials
• Writing your own ROS package.

Detailed description for URDF tutorials:¶

• Building a Visual Robot Model with URDF from Scratch: tutorial_urdf_1.pdf
  • For your convenience add your URDF files in urdf directory of package beginners_tutorials, the one created during the first laboratory.
  • In next sections create new URDF files according to roslaunch files.
  • The final version of r2d2 has different gripper.
• Building a Movable Robot Model with URDF: tutorial_urdf_2.pdf
  • Continue creating new URDF files.
• Adding Physical and Collision Properties to a URDF Model
  • You can omit this section, as we do not use model of dynamics and friction.
• Using Xacro to Clean Up a URDF File
  • The practical example in this section is not working properly.
• Understanding the PR2 Robot Description
  • You can omit this section.
• Create your own urdf file: tutorial_urdf_6.pdf
  • Create new URDF files.
  • ROS Kinetic is newer than ROS Hydro
• Parse a urdf file
  • Copy URDF file from beginners_tutorials package
• Using the robot state publisher on your own robot
  • This section is unclear and can be omited.
• Start using the KDL parser
  • You can omit this section.
• Using urdf with robot_state_publisher
  • This section shows a method to move the model of robot written in URDF file.

The task:¶

• Create a new package in your repository created in the previous laboratory.
• Create a program (can be a ROS node) that calculates rotation parameters (RPY or quaternion), compatible with URDF format, from DH parameters.
  • You may find KDL documentation useful: http://wiki.ros.org/kdl
• Create URDF file for a robot with given parameters expressed in Denavit-Hartenberg notation
  • You can create base for the robot with arbitrarily chosen height.
  • Add a tool with no internal degrees of freedom
  • Parameters (e.g. length of a link) should be read from ROS parameter server
• At first, treat all joints as fixed.
• Create a roslaunch file and visualize the robot in RVIZ using robot_state_publisher.
  
• Create second URDF file with moveable joints
• Create second roslaunch file that runs joint_state_publisher to move joints.
  • Both roslaunch files should be executed in separate terminals. The first one runs RVIZ as long as the URDF file is unchanged. The second runs the rest of the system.
    
• Commit and push your work to GitHub.
• Add wiki page to your repository (the documentation). The page should contain description of source files, instruction for launching and description of tests.
  • Additionally, upload graph and description of structure of the system with communication mechanisms. Add a graph with structure of the manipulator.
  • Describe the tests. Use tools such as rqt_plot to plot changes of some variables in ROS topics (e.g. joint state, tf).
• Test the system and show it to the tutor.