Robotiq grippers on robot arm

[clint p]

Hello,

I am a ROS user and I'm working with a robotiq gripper attached to an sia5 motoman arm. It looks like this:

http://www.youtube.com/watch?v=TwXBoyqP__U&feature=youtu.be

I've got the arm working with just the articulated gripper model attached, but it doesn't open or close. I would like to have the gripper visually open and close in Rviz, similar to what Willow Garage did with their GraspIt! software: 

http://youtu.be/kZ3G0h7Gpo8?t=29s

Instead of editing the hell out of my urdf, I'd like to ask if gripper visualization (i'm talking about opening/closing too) in Rviz already exists.

Thanks!

[Shaun Edwards]

Cool video.

I'm pretty certain Willow Garage created a joint state publisher for the articulated urdf ( https://github.com/ros-industrial/robotiq/blob/groovy-devel/robotiq_s_model_visualization/cfg/s-model_articulated.urdf ).  The joint state publisher would publish the GraspIt defined joint positions when the object was grasped (at the end of the Willow Garage video).

Let me know if you need more info,

Shaun

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[clint p]

I'm not actually using GraspIt! with this robot. I just need a 3d visualization of the gripper when I send commands to the hardware via TCP modbus. Ideally I would like to get the actual joint values from the hardware after a command is sent (open gripper, close gripper, etc). Then I could use the joint values and update the model in rviz. I'm not sure if the robotiq stack has that kind of support, though...

I'm a ROS novice. Am I correct in saying that the joint state publisher exclusively publishes information about the robot model in ROS and not the actual hardware?

Thanks for the response, Shaun.

-Clint

[Brian O'Neil]

Hi Clint,

You can set up a joint state publisher to publish joint states from whatever source you want. The trick is that there is no easy way to get the hardware joint state of the robotiq gripper because it is underactuated. You can read the registers of the gripper, but you will only know the positions of the actuated joints. Something like GraspIt would be required to fill in the passive joints by modeling contact with the object.

--Brian

Brian O'Neil
Posdoctoral Research Associate
Nuclear Robotics Program

University of Texas at Austin

Phone: (480) 363-8963

[asif...@gmail.com]

Hi clint,

I am also working on a robotiq gripper attached to a UR10 arm and I am trying to integrate the gripper in by robot's URDF model visualise it in Rviz. Do you have a URDF model for the gripper which can serve the purpose?

Thanks

[clint p]

Hi there,

Sorry I'm late getting back to you. If you haven't got it already, all I did was modify the xacro file that came with the motoman package from ROS-I (I'm sure the UR10 arm has some xml that is similar). I added a fixed joint at the end of the xacro that meshes the robotiq xml (xacro in this case) with the end effector of my robot. 

Here's what I added:

  <xacro:s-model_articulated prefix=""/>

  <joint name="robot-hand" type="fixed" >

    <origin xyz="0.06 0 0" rpy="1.57 1.57 0"/>

    <parent link="${prefix}link_t" />

    <child link="${prefix}palm" />

  </joint>

  

</xacro:macro>

You may have to play around with the origin position and rpy to get it to look right. After that, I made a new xacro file that I could load from moveit's setup assistant:

<?xml version="1.0" ?>

<!-- 

s-model_articulated - articulated version of the robotiq s-model,

3 fingered gripper.                                                

-->

<robot name="s-model_articulated" xmlns:xacro="http://ros.org/wiki/xacro">

<xacro:include filename="$(find sia5d_config)/cfg/sia5d_robotiq_macro.xacro"/>

<xacro:sia5d prefix=""/>

</robot>

Hope it works out for you

-Clint

[heloise...@gmail.com]

Hi Shaun,

Hi use a robotiq gripper with a lwa arm and added the articulated model to the urdf. I added the passive joints to my srdf file for MoveIt but I have now a segmentation fault when I try to move the arm with MoveIt. When I send a goal from Rviz it is working well, but I can't run a node from my own. Any idea?

Thanks

Heloise