The Jaco URDF model

This package contains the URDF model for the Kinova Jaco arm.

The following page describes:

• How to load up the existing URDF in Gazebo
• How to integrate the arm into your robot.

Notes

Experiments showed that the robot description in the kinova specs (see the documents in jaco_description/docs) did not match the robot hand perfectly: How the robot saw itself with an Xtion camera, did not match the model displayed in RViz. Some corrections were made to the parameters in order for it to match the real arm more closely.

These corrections can be found in the jaco.urdf.xacro file, searching for MODEL_FIX. (in the current version, some of the fixes are commented out however). The meshes around the finger bases are not well fitted for the new parameters. Designing new meshes it part of future work. See also README.ModelChanges.md for more details.

Jaco in Gazebo (without joint controllers)

You can load up the robot without joint controllers for test purposes, or as a starting point to integrate your own controllers.

The basic URDF file does not load the Gazebo joint controllers, so the arm will collapse after loading. The Jaco Gazebo tutorial includes instructions on how to load up the Jaco with constroller instead.

You can either

1. use the example launch file or
2. spawn the robot URDF separately

Option 1. Use example launch file to start gazebo and load robot

To launch gazebo and spawn the standalone arm from a single launch file:

roslaunch jaco_description jaco_standalone_gazebo.launch

And to launch the jaco arm mounted on a table:

roslaunch jaco_on_table jaco_on_table_gazebo.launch

Option 2. Spawn the robot into gazebo

You may also spawn the robot into an already running gazebo world.

The repository only offers the xacro files, so to spawn the Jaco, you will have to convert the urdf first:

rosrun xacro xacro --inorder <your-xacro-file>.xacro > <your-urdf-output-file>.urdf

Launch gazebo (with empty_world):

rosrun gazebo_ros gazebo

And spawn the arm only:

rosrun gazebo_ros spawn_model -file `rospack find jaco_description`/urdf/jaco_robot.urdf -urdf -x 0 -y 0 -z 0 -model jaco_robot

or the arm on the table:

rosrun gazebo_ros spawn_model -file `rospack find jaco_on_table`/urdf/jaco_on_table.urdf -urdf -x 0 -y 0 -z 0 -model jaco_on_table

Integrate the Jaco in your URDF

1. Create a new ros package

Create a new ROS package for your URDF that should include the Jaco arm (or go to the existing package) and add the following dependencies.

catkin_create_pkg <your-robot-name>_description xacro jaco_description

2. Create URDF

Create a folder "urdf" within this package. In this, create a top-level URDF YOUR_ROBOT.urdf.xacro based on the following frame (which is of course a template only):

	<?xml version="1.0"?>
	<robot name="<your-robot-name>" xmlns:xacro="http://ros.org/wiki/xacro">

		<!-- Included URDF Files -->
		<xacro:include filename="$(find <yourpackage>)/urdf/<your-robot-include>.urdf.xacro" />

		<link name="robot_base">
			<static>false</static>
		</link>
		
		<!-- Add your robot via a macro -->
		<xacro:your-robot-macro parent="robot_base"/>
		
		<!-- Add the JACO arm to the given parent link with the given transforms -->
	    <xacro:jaco_arm parent="link-on-your-robot"
                        mass_divider="2" finger_mass_divider="1">
	      <origin xyz="0 0 0" rpy="0 0 0" />
          <!-- set to true if you would like to add <transmission> tags -->
          <xacro:arg name="add_transmission_pos" default="true"/>
          <xacro:arg name="add_transmission_vel" default="true"/>
	    </xacro:jaco_arm>
	</robot>

The mass_divider parameters can be used to make the whole robot lighter or heavier. The origin tag is the transform used for the joint connecting arm_support_link with the jaco arm.

The important thing is to include the macro xacro:jaco_arm and declare the parent link as a link in your other robot to which you want to attach the arm (it do not have to be "robot_base" like in the example). The origin tag can be used to specify the transform of a fixed joint which will be created to connect the Jaco to your link.

The tags add_transmission_pos and add_transmission_vel can be set to true to include the <transmission> tags. There generally should be no harm in loading them even if you do not need them. Best take a look at the URDF for more details about this:

rosed jaco_description jaco.urdf.xacro

3. Create the launch file

Create a folder "launch" within the package and add a launch file to get up gazebo and/or the robot.

You may include the following convenience launch file from your own launch file:

rosed $(find jaco_description)/launch/jaco_gazebo.launch

There are a number of arguments which are documented within this file. For instance, you have to set your robot urdf as argument here. For an example, see this launch file which loads up just the Jaco arm:

rosed $(find jaco_description)/launch/jaco_standalone_gazebo.launch

4. (optional) Integrate the arm with MoveIt!

Please refer to the jaco_moveit wiki page and the Jaco MoveIt tutorial for instructions on how to set up the arm with MoveIt!.

5. (optional) Add gazebo plugins

The URDF files do not load gazebo plugins to control the joints. You can find examples for joint controllers along with examples on how to include them in the model in the package jaco_gazebo, also described on the jaco_gazebo wiki page.