denso_arm_control

Denso arm controller for ROS using the b-CAP protocol. This code has been tested with the 6-axis Denso VS050 and Denso controller RC8. The compilation has been verified using catkin-tools in a ROS Kinetic (Ubuntu 16) and ROS Noetic (Ubuntu 20) environments.

Prerequisites

Prerequisities included in this repository;

• TRAC-IK
• realtime_scheduler_interface

Prerequisities not included in this repository and you need to install independently.

sudo apt install ros-noetic-geometry-msgs liborocos-kdl-dev ros-noetic-kdl-parser ros-noetic-eigen-conversions ros-noetic-dynamic-reconfigure ros-noetic-ros-control ros-noetic-joint-limits-interface ros-noetic-actionlib ros-noetic-controller-manager qt5-default 

ROS nodes:

This package includes the following nodes:

• denso_arm_control: contains the low-level controller that handles the b-CAP protocol communication with RC8. It uses a ros-control implementation. It contains the following topics:

  • /position_controller/command : (Subscriber) Receives the joint position command
  • /joint_states : (Publisher) Publishes the current robot joint positions

• denso_arm_gui: contains the graphical user interface to start the robot control.

• denso_arm_planner: contains a high-level planner. It requires the TRAC-IK library and the Reflexxes TypeII motion planner (both are contained in this repository). It requires a URDF model loaded in the ROS parameter server to solve the IK. It provides two ROS Action servers:

  • /FollowJoint : Action that receives a sensor_msgs/JointState goal and generates a smooth joint trajectory to the desired goal by using the Reflexxes library
  • /FollowTool : Action that receives a geometry_msgs/Pose goal, solve the IK by using TRAC-IK and generates a smooth joint trajectory to the desired goal by using the Reflexxes library

• denso_arm_example: contains a ROS Action client to generate sample commands for the /FollowJoint action server and the /FollowTool action server. Use it as a base to create your own robot controller.

Launch file

The launch file located in /launch/denso_arm_contro.launch allows to enable and dsiable the execution of the ROS nodes. It also allows configuration of the follwoing parameters:

• prefix : It appends a prefix to the topics and server names. Useful if you are using more than one robot.
• name : String robot identifier. Useful if using more than one robot.
• robot_identifier: Numerical robot identifier. Useful if using more than one robot.
• robot_ip: IP address of the robot. Make sure the local compute and the robot are in the same network (ifconfig: to check yout current IP address; ping robot_ip_address: to verify your PC is in the same network as the robot)
• robot_sim: Defines if you are using the robot simulator or the real robot. By default is set to True, if you will use the real robot change it to False. Recommendation: Try the controller with the simulation first.
• thread_sampling_time_nsec: control loop time expressed in nanoseconds.
• robot_description: URDF file path. Required for the denso_arm_planner node.
• robot_config.yaml: Robot configuration file path with joint and velocity limits. Required for the denso_arm_control node. Modify it according to your robot configuration.
• pos_control.yaml: Controller configuration file. Require for the denso_arm_control node. Defined for a 6-DOF robot.
• controller_spawner: Initializes the controller manager required for the ros-control package.

URDF file

A URDF file for the Denso VS050 robot is located in /urdf/vs050.urdf. The URDF file is needed for the TRAC-IK and the simualtion environment setup. To generate your own URDF file you can follow this guide. Additionally, if you have the CAD model of the robot, the Solidworks URDF Exporter add-in will be quite useful.

GUI

This package includes a GUI developed with QT (soure code located in /src/qt/).

• Sequence for activation is:
  1. Connect: Establish a connection with the robot.
  2. Motor On : Activates the robot motors (Make sure you are in a safe environment).
  3. Slave Mode: Start the Slave mode for joint position command.
• Sequence for desactivation follows the inverse order:
  1. Slave Mode: It will release the slave mode.
  2. Motor Off: It will stop the motors
  3. Disconnect: It will disconnect the robot

Dynamic reconfigure

The node denso_arm_planner allows you to modify the maximum join velocity and maximum joint acceleration online through the dynamic reconfigure package. The absolute maximum velocity is set to 200 deg/s and the absolut maximum acceleration is set to 50deg/sec2. By default the maximum velocity and acceleration is set to 50% of the absolute maximum. You can modify this parameter by executing (after launching the denso_arm_planner node):

rosrun rqt_reconfigure rqt_reconfigure

The slider varies from 1% to 100%.

Simulation

The package includes a simulation environment of the VS050 implemented with CoppeliaSim located in:

 ./sim/vs050.ttt

The simulation model contains the the following ROS topics for communication with denso_arm_control:

• Subscriber:

  • /sim/joint/cmd: Receives a joint position command to control the robot

• Publishers:

  • /sim/joint/state: Publishes the current joint states
  • /sim/tool: Publishes the current tool frame pose

• CoppeliaSim: The simulation environment has created using CoppeliaSim v4.1. It uses the ROS plugin that requires ROS to be launched before initializing CoppleiaSim (i.e. run roscore before launching CoppeliaSim)

Publications

This code has been used as the core controller for the following publications. For further references please follow the links:

• Colan, Jacinto, et al. "A Cooperative Human-Robot Interface for Constrained Manipulation in Robot-Assisted Endonasal Surgery." Applied Sciences 10.14 (2020): 4809.

• Colan, Jacinto, et al. "Optimization-Based Constrained Trajectory Generation for Robot-Assisted Stitching in Endonasal Surgery ." Robotics 10.1 (2021): 27.