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KemroX Custom Robot

With the drag&bot KemroX robot driver it is possible to display and control a self-defined kinematic which was created in KeStudio. The robot is controlled from drag&bot with the KemroX RcApi interface, while the displayed robot kinematic, meshes and settings can be configured by the user.

Prerequisites

This tutorial assumes

  • that you are familiar on how to use the drag&bot overlay system.
  • that you are familiar using git and that git installed on the target system.
  • that a valid URDF file with mesh files for each robot link does exist. Otherwise, it is not possible to show a robot model in drag&bot.

Setup

  1. Clone the dnb_kemrox_custom_robot ROS package into the drag&bot overlay.
  2. Add/Modify the files in the package for the robot to be integrated:

URDF File

The URDF (Unified Robot Description Format) file describes the kinematic of the robot. Here the chain of alternating links and joints is described. Each link is represented by one transformation (tf) frame, where a mesh is attached to. Later, when the joint values are received from the controller, these are applied to each joint and the displayed robot is placed in the corresponding position. In drag&bot the URDF file is almost exclusively used for displaying purposes. The following graph shows the chain of links and joints for a six-axis robot as it is used in drag&bot:

graph LR base_link(("base_link")) joint_1["joint_1"] link_1(("link_1")) joint_2["joint_2"] link_2(("link_2")) joint_3["joint_3"] link_3(("link_3")) joint_4["joint_4"] link_4(("link_4")) joint_5["joint_5"] link_5(("link_5")) joint_6["joint_6"] link_6(("link_6")) joint_fixed["joint_fixed"] ee_link(("ee_link")) base_link --> joint_1 joint_1 --> link_1 link_1 --> joint_2 joint_2 --> link_2 link_2 --> joint_3 joint_3 --> link_3 link_3 --> joint_4 joint_4 --> link_4 link_4 --> joint_5 joint_5 --> link_5 link_5 --> joint_6 joint_6 --> link_6 link_6 --> joint_fixed joint_fixed --> ee_link

By convention robot URDFs always start with the base_link frame/link and end with ee_link. The joints are named joint_1 to joint_6 for a six axes robot.

Adjust your URDF file to meet the naming conventions of the joint and link names and save it as custom_robot.urdf in the urdf/robot directory of the ROS package. You can use the existing file as a template when creating the URDF from scratch.

Mesh Files

The robots mesh files are placed in the meshes directory of the ROS package. Maybe you have to adjust the stated mesh paths in the URDF file respectively.

Module Config Files

The robots' module config file module_config/robot/kemrox_custom.yaml needs to be adjusted. Most of its parameters are for the drag&bot control panel and should already work. The joint limit parameters however might have to be adjusted. See the Control Panel interface how to configure the parameters for the control panel.

After all settings are configured, restart the robot system.

Setup for drag&bot Studio

  1. Select KemroX Custom Robot from the dropdown menu in the drag&bot Component Manger.
  2. Configure the parameter IP for your robot. It can be found in the KeStudio project, if unknown. By default, a KemroX robots IP address is 192.168.100.100.
  3. Configure the parameter Robot Name as the robot is named in the KeStudio project.
  4. Activate the option Use URDF and meshes, if these are configured in the ROS package described above. Deactivate the option otherwise to avoid loading of non-existent files.