Trouble getting gripper interactive markers to show in RViz

[Patrick Goebel]

Hello,

I have a simple box-and-cylinder model of a 6-dof one-armed robot with gripper (URDF file attached) and no matter how I configure the arm and gripper planning groups in the setup assistant, I cannot get the interactive markers for the gripper to show up in RViz when running demo.launch.  The arm interactive markers show up and work perfectly so I'm not sure what to do to get the gripper working.  Note that the gripper has only one active finger joint with the other finger fixed.  And yes, I am selecting the gripper planning group in RViz.

The only clue I have is the following INFO output when launch demo.launch:

[ INFO] [1389543366.960775457]: No active joints or end effectors found for group ''. Make sure you have defined an end effector in your SRDF file and that kinematics.yaml is loaded in this node's namespace.

I have attached my SRDF and kinematics files as well.  And here is a screen shot with the right_gripper selected but with no interactive markers:



Thanks!
patrick

[Sam Pfeiffer]

Why should there be a interactive marker only for the gripper?

I don't have a marker either for my grippers (hands) in my robot. The only markers I have are the ones of the terminal element of a group (like, I have a group "right_arm" and the last element is "tool_link" where a "right_hand" is attached). I have markers for this "tool_link". I also have a "right_arm_grasping" now which has as last element "grasping_frame" which is a frame in the position where I want my grasped objects to be so I have this interactive marker centered in this grasping point. Maybe that is useful for you, it was for me.

[Patrick Goebel]

Thanks Sam,

For some reason I thought there would be an interactive marker for whichever group was selected, including the gripper group.  And with the gripper group selected in RViz, I figured you'd be able to move the finger using the interactive marker.  I vaguely remember this is the way it work in the old arm_navigation setup but I could be wrong.  And if doesn't work that way in MoveIt!, then I guess I'm OK.  However, I am still concerned by INFO message below that seems to indicate that something is wrong.

In the meantime, thanks for the tip regarding the grasping frame.  That will come in handy when I get to pick and place.

--patrick

On 01/12/2014 02:56 PM, Sam Pfeiffer wrote:

Why should there be a interactive marker only for the gripper?

I don't have a marker either for my grippers (hands) in my robot. The only markers I have are the ones of the terminal element of a group (like, I have a group "right_arm" and the last element is "tool_link" where a "right_hand" is attached). I have markers for this "tool_link". I also have a "right_arm_grasping" now which has as last element "grasping_frame" which is a frame in the position where I want my grasped objects to be so I have this interactive marker centered in this grasping point. Maybe that is useful for you, it was for me.

El domingo, 12 de enero de 2014 17:29:08 UTC+1, Patrick Goebel escribió:

Hello,

I have a simple box-and-cylinder model of a 6-dof one-armed robot with gripper (URDF file attached) and no matter how I configure the arm and gripper planning groups in the setup assistant, I cannot get the interactive markers for the gripper to show up in RViz when running demo.launch.  The arm interactive markers show up and work perfectly so I'm not sure what to do to get the gripper working.  Note that the gripper has only one active finger joint with the other finger fixed.  And yes, I am selecting the gripper planning group in RViz.

The only clue I have is the following INFO output when launch demo.launch:

[ INFO] [1389543366.960775457]: No active joints or end effectors found for group 'right_gripper'. Make sure you have defined an end effector in your SRDF file and that kinematics.yaml is loaded in this node's namespace.

[Michael Ferguson]

I don't think arm-navigation did the gripper marker, are you possibly thinking of the turtlebot_arm_interactive_marker package (which did have this feature)?

-Fergs

[Sam Pfeiffer]

Yeah I was thinking you were missing that feature from some move_arm application.

Update us if you find an easy way to move individual joints with markers please :) that was a handy tool indeed.

[Patrick Goebel]

Thanks Fergs. That could well be what I was thinking of. Also, I think
arm navigation had a mode where you could set joint angles
individually. So I guess my setup is OK.

--patrick

[Acorn (Nathan) Pooley]

Usually Moveit does not show interactive markers for the gripper (end effector) group.  When it shows interactive markers for an arm group it does so by looking for end effectors attached to the links in the group, and adds a marker for any such end effector it finds.  Since the end effector group does not have (yet another) end effector attached to it moveit does not add an interactive marker.

I think that if you define your gripper group as a chain (in setup assistant (recommended) or by editing the srdf file itself (if you understand the file format))  that moveit will add an interactive marker at the end of the chain (i.e. allow you to use it to move the gripper).  For this to work the gripper group has to be a chain: a single linear arrangement of link-join-link-join-link...   If your gripper is a single joint (e.g. with a hand link on one side and a finger link on the other) then this would also be considered a chain and should work.

I think this will work because moveit will add an interactive marker for a chain group if the group does not have any eef attached.  But I have not tried it so I don't know for sure.

-Acorn

---

From: moveit...@googlegroups.com [moveit...@googlegroups.com] on behalf of Patrick Goebel [pat...@pirobot.org]
Sent: Sunday, January 12, 2014 4:57 PM
To: moveit...@googlegroups.com
Subject: Re: Trouble getting gripper interactive markers to show in RViz

[Patrick Goebel]

Thanks Acorn,

I gave that a try and it didn't seem to result in an interactive marker on the gripper.  I also tried it with a pan-and-tilt head by defining a chain for the pan-and-tilt servos and camera and that also did not result in an interactive marker for the head.

--patrick

[Sachin Chitta]

Could you give it a try defining the group using a sequence of joints instead of a chain to define the group?

Sachin

[Patrick Goebel]

Hi Sachin,

Same result if I use a sequence of joints instead of a chain--no interactive marker when that group is selected in the Motion Planning display.

--patrick

[Patrick Goebel]

OK, I was able to get interactive markers on my robot's camera link by defining a head group with the servo and bracket joints and a camera group with just the camera link.  I then defined an end-effector for the camera group that attaches to the head group.

The only catch is that the interactive marker rotation controls don't properly line up with the pan and tilt joints.  The tilt control works fine, but the pan control tilts when you tilt the camera so it no longer lines up with the rotation plane of the pan joint so you can no longer pan the camera.  Hope that makes sense.

--patrick