Lab 5: Inverse kinematics¶

Scope:¶

This laboratory consists of two parts:

• A short introduction.
• Writing your own ROS package.

The task:¶

• Develop the system from the previous laboratory by either copying the package or modifying it.
• Create ROS node IKIN that calculates inverse kinematics (IK) of the manipulator.
• Create an analytical algorithm for IK without use of KDL.
• Ignore orientation of the end effector. In this task, only position (translation) is relevant.
• The node should use the same ROS parameters as previously implemented node DKIN.
• Commands for IKIN should be read from the node that interpolates trajectory in operational space.
• The calculated joint position should be sent to robot_state_publisher.
  • If IK cannot be solved, the node IKIN does not publish new position and it sends error information to ROS log.
• Compare two positions in RVIZ:
  • The one calculated by the node that interpolates trajectory in operational space.
  • Position calculated by robot_state_publisher.
    
• Send a number of commands to operational space interpolation node and check if they are executed properly.
  • In particular, the node ocmd commands motion of the end effector that follows rectangle and ellipse shape. Each motion should be executed periodically. The trajectory should be visualized as a streak in RVIZ. * Set such physical parameters of the manipulator (e.g. lengths of links) that the desired example motion is possible.
• Each example motion should be executed successfully for any initial configuration of the robot.
  • You can set the initial position using the method from the previous laboratory (i.e. interpolation in joint space).
  • Chose such solution for IK that the robot does not make any discontinuous motions.
    • Do not add any limits in joint space.
• Additionally:
  • Take into account limits of IK for the workspace of the robot.
    • If IK cannot be solved, the node should not publish new position and it should send error information to ROS log.
• Add wiki page to your repository (the documentation). The page should contain description of source files, instruction for launching and description of tests.
  • On all graphs of structure of the system topics and services should be shown differently.
  • The plots generated with rqt_plot should prove compatibility of poses of end effector calculated in different streams with the position calculated by interpolator (with and without IK).
• Use separate roslaunch files for:
  • roscore and RVIZ (it should be running until URDF file is modified).
  • The rest of the system.
• Test the system and show it to the tutor.