Skip to content

Latest commit

 

History

History
130 lines (96 loc) · 8.35 KB

README.md

File metadata and controls

130 lines (96 loc) · 8.35 KB
Raw

Preliminaries: Package Organization

This package groups all the ROS code of the Comau driver.
The following table lists the libraries and nodes provided by the package.

comau_driver/
comau_driver/comau_trajectory (README)
comau_driver/comau_joint_streamer (README)
comau_driver/comau_joint_trajectory_action (README)
comau_driver/comau_motion_feedback (README)
comau_driver/comau_robot_status (README)

Libraries Description
comau_trajectory It provides the class JointTrajectoryInterface. It is the message handler that relays joint trajectories to the robot controller.
comau_joint_streamer It provides the class ComauJointTrajectoryStreamer. it is the message handler that streams joint trajectories to the robot controller.
comau_joint_trajectory_action It provides the class ComauJointTrajectoryAction. It is the TrajcetoryActionServer.
comau_motion_feedback It provides the class MotionFeedbackComau. It is the message handler that receives the motion feedback from the robot.
Nodes Description
comau_joint_streamer_node It handles the trajectory loading and the dispatching of the points to the robot controller.
comau_joint_trajectory_action_node It handles the trajectory action server.
comau_motion_feedback_node It handles the robot feedback and the trajectory execution status
Actions Type Description
/joint_trajectory_action control_msgs::FollowJointTrajectory Standard action. Used to load a standardized trajectory and send it to the robot controller
/comau_joint_trajectory_action comau_msgs::ComauJointTrajectory Customized action. Used to load a full description trajectory and send it to the robot controller
Services Type Description
/start_motion industrial_msgs::StartMotion Send to the robot the start motion command. It trigger the start of a new trajectory, or a previous stopped trajectory
/stop_motion industrial_msgs::StopMotion Send to the robot the stop motion command, the motion can be resumed calling /start_motion
/cancel_motion industrial_msgs::StopMotion Send to the robot the cancel motion command, the motion cannot be resumed and the trajectory on the controller is deleted
/joint_path_command comau_msgs::CmdJointTrjComau Load a new trajectory and send it to the robot controller
/reload_trj _industrial_msgs::StartMotion Re-send the previously loaded trajectory to the robot controller
Topics Type Description
/joint_states sensor_msgs::JointState ROS-I standard feedback
/motion_feedback comau_msgs::MotionFeedbackComau Feedback with some additional information (doc here)
/comau_trajectory_sts std_msgs::Int32 Status of the trajectory (doc here)

Usage Notes

  1. Driver Architecture: The driver architecture is both a "streamer" and a "downloader" as defined at http://wiki.ros.org/Industrial/supported_hardware.

  2. Starting the Motion Execution: The start_motion command is given by the user (on purpose, for sake of security), otherwise the robot will not start the movement.

  • The start_motion is a ROS-service provided by comau_joint_streamer_node (class JointTrajectoryInterface, declaration in comau_joint_trajectory_interface.h). The ROS-service start_motion is of type industrial_msgs::StartMotion. The callback start_motion in the COMAU Robot Controller is declared in ../PDL_programs/Single_Arm/ROS_COMAU_motion.pdl

  • The service start_motion can be called before the trajectory download is finished. A thread on the ROS side sends the points of the trajectory, and the robot movement is allowed also during the trajectory download (whether unprocessed points are still in the circular buffer).

  1. Trajectory Processing: The ROS-node stores the trajectory in a queue (no fixed capacity, and therefore the trajectory length is not limited), while the the trajectory on the robot controller side is stored in a circular buffer of capacity of 200 points.
  • The ROS-node and the COMAU robot controller communicate through a TCP/IP connection.
  • The ROS-node extracts one point at time from the trajectory queue.
  • The ROS-node keeps sending the point to the COMAU robot controller as long as the circular buffer in the robot controller is not completely full.
  • The movement interpolation is always a Cartesian Linear movement (extension to joint movement asap).
  • The MOVEFLY command from COMAU is used to interpolate the sequence of points.
  • The movement on the last trajectory point is a simple MOVE command from COMAU interpolator.
  • The linear speed value to reach each point is mandatory and have to be set by the user in the trajectory definition.
  1. Robot State Monitoring: the comau_driver can be used just to online monitor the robot state.
  • The robot positions are in joints coordinates (in degrees, with COMAU conventions).
  • When a parallogram robot is used (e.g. NJ220), the joint values correspond to the joint vaules of the URDF kinematics. Pay attention that the actual values in COMAU Joint Convention are therefore different due to the coupling of the kinematics of joint 2 and 3
  1. Configuration: The configuration files (YAML) could be different for each robot. Therefore, they are stored in the available comau_ROBOTNAME_support packages.
  • The IP address of the robot controller is loaded in the param server in launching the driver execution

Warning: Sometimes, when the ROS part of the driver crashes unexpectedly, the internal mutex is not canceled from the memory, hence it must be done manually before restarting the driver.
To do so, type rm /dev/shm/sem.jnt_trj_shared_mtx in a command shell.

Launch driver

The package provides a launch file, launch/comau_driver.launch

The launch file loads the generic version of comau_driver (while the proper configurations are loaded by each specific robot implementation, see comau_robots).
Therefore, it is strongly suggeste to launch comau_ns16hand_driver.launch or comau_nj220hand_driver.launch or other specific robot launch files

Usage:
comau_driver.launch robot_ip:=<value> joint_names_config_file:=<value> [only_monitoring:=<true|false>]

Arguments:

  • robot_ip: is the address of the robot controller (check ping before)
  • joint_names_config_file: yaml file with the joint names (check that the names list is equivalent to the set in the URDF)
  • only_monitoring: if true, the driver allows just the monitoring of the robot data

Defaults provided:

  • only_monitoring = false

Example of Usage

A example of usage of the ROS-I Comau driver is in comau_driver/test.

The trajectory used in the example is defined in the config file comau_driver/test/example_trj.yaml that has to be load in the parameter server before running the code.

Usage:
rosparam load comau_driver/test/example_trj.yaml
rosrun comau_driver comau_action_client_trj_test
or
rosrun comau_driver standard_action_client_trj_test

WARNING!

  • The example trajectory is made for a Comanu NS16-Hand robot with a free workspace!
    Change the joint positions if you have a different robot or some constraints on robot movements.

Trajectory points are sent using a parallel thread which doesn't interfere with the main program execution.
The comau_trajectory_sts topic is available to check the status of the trajectory execution.

IMPORTANT!

  • For safety reasons, the start_motion command is not given automatically.

  • To start the motion call the service start_motion manually in the command shell.
    rosservice call /start_motion {}

  • To cancel the motion call the service cancel_motion manually in the command shell.
    rosservice call /cancel_motion {}

  • To stop the motion call the service stop_motion manually in the command shell.
    rosservice call /stop_motion {}