Ask Your Question

Nash's profile - activity

2018-02-13 11:13:09 -0500 received badge  Guru (source)
2018-02-13 11:13:09 -0500 received badge  Great Answer (source)
2017-02-23 14:49:36 -0500 received badge  Popular Question (source)
2017-02-23 14:49:36 -0500 received badge  Famous Question (source)
2017-02-23 14:49:36 -0500 received badge  Notable Question (source)
2015-10-29 12:11:26 -0500 received badge  Good Answer (source)
2015-10-29 12:11:26 -0500 received badge  Enlightened (source)
2014-01-28 17:22:31 -0500 marked best answer Disabling the head from tracking the executed trajectory of the arm

When using the move_arm package, the head would track the arm moving along the collision-free trajectory it found. I was wondering if there was an option to switch this functionality off since it would be great if the head kept looking at the target and not have to abruptly monitor the arm once the trajectory is found.

Did anyone figure out how to solve this issue?

2014-01-28 17:22:24 -0500 marked best answer station running roscore cannot listen to rostopics from other stations

We have an issue communicating with rostopics and are looking for a work-around (or at least explanation of the issue).

Suppose station A is running roscore and station B has mapped its ros master uri to station A. Both station A and station B can see the full list of rostopics. If station B publishes a topic, station A can subscribe to it, but it never receives any messages (for instance 'rostopic echo <topic_name>' never has output). If station A subscribes to it, 'rostopic info' will show station A as a subscriber and station B as a publisher.

However, station A can publish messages to itself and can also receive service requests from station B.

Do you know why station A cannot receive messages from station B? Does this seem like a network issue or is this an inherent/intended ROS feature?

In response to mwise_wg, setting the ROS_IP of station A to itself didn't change the behavior. Same with setting ROS_HOSTNAME on station A to it's own name. roswtf returns "ERROR Could not contact the following nodes: * /rostopic_3179_1..." and "ERROR The following nodes should be connected but aren't:

2014-01-28 17:22:21 -0500 marked best answer Multiple solutions from IK solver?

Is it possible to obtain multiple IK solutions for all the joints of an arm from the IK Solver (pr2_right_arm_kinematics/get_ik) for one specific pose of a link (i.e. r_wrist_roll_link)?

2014-01-28 17:22:04 -0500 marked best answer Running several nodes under a "top" node

I have organized my code in such a way that when I run a "main" file, it calls methods in other classes, from other packages, to accomplish a task. I soon realized that the classes written, requires a rospy node so that it can communicate with ROS_MASTER. But I cannot initialize other nodes under the "main" node as i think ROS only allows one node to be initialized and not a node inside another.

Example: The classes in the other packages use SimpleActionClient/action client which uses the actionlib, that requires to initialize a node to publish messages and call services. I had only initialized a node for the "main" method. And since I cannot initialize any more nodes, the code does not really do anything

Any advice on how to resolve this issue? or any alternative ideas?


2014-01-28 17:22:02 -0500 marked best answer Waiting for action server when using SimpleActionClient

In my code, I have constructed a SimpleActionClient with the MoveArmAction interface to communicate with move_right_arm action. I have also launched the right_arm_navigation.launch file from pr2_3dnav, but the code does not get past the "move_arm.waitForServer()". It does not throw any errors and the terminal where I launched the right_arm_navigation.launch shows the same "Move arm action started" message before and after I ran my code. I tried reading the debugging messages from the rxconsole, but didnt get very far. We are currently using Diamondback on our PR2.

Does anyone have/had the same problem?



2013-05-05 11:19:41 -0500 received badge  Nice Answer (source)
2013-03-21 08:50:18 -0500 received badge  Nice Answer (source)
2013-03-06 15:52:09 -0500 commented answer OpenNI/NITE incompatible in Fuerte/Groovy on Precise

Thanks!, your suggestion of reinstalling Nite v1.5.2.21 worked!

2013-01-24 15:15:10 -0500 received badge  Taxonomist
2013-01-23 03:01:48 -0500 received badge  Nice Question (source)
2012-11-09 15:53:06 -0500 marked best answer service exception using tf listener in rospy

I get a service exception whenever I call lookupTransform for tf.TransformListner.

tf_listener = tf.TransformListener()        
tf_listener.waitForTransform( reference_link, end_effector_link, rospy.Time(), rospy.Duration(4.0))     
(posn, rotn) = tf_listener.lookupTransform(reference_link, end_effector_link, rospy.Time())

This is the service exception:

Exception in thread Thread-18:
Traceback (most recent call last):
  File "/usr/lib/python2.6/", line 532, in __bootstrap_inner
  File "/opt/ros/diamondback/stacks/geometry/tf/src/tf/", line 237, in run = rospy.Service('~tf_frames', FrameGraph, self.frame_graph_service)
  File "/opt/ros/diamondback/stacks/ros_comm/clients/rospy/src/rospy/impl/", line 682, in __init__
    get_service_manager().register(self.resolved_name, self)
  File "/opt/ros/diamondback/stacks/ros_comm/clients/rospy/src/rospy/", line 120, in register
    raise ServiceException(err)
ServiceException: service [/test_code_22488_1312164786316/tf_frames] already registered

The tf_listener is initialized within a python function definition. The output of the lookupTransform is otherwise fine (the position and rotation are correct and functional). I just want to get rid of the exception always printing out the screen about the service being already registered.

2012-09-12 05:09:24 -0500 received badge  Notable Question (source)
2012-09-12 05:09:24 -0500 received badge  Famous Question (source)
2012-09-06 12:17:50 -0500 received badge  Famous Question (source)
2012-09-06 12:17:50 -0500 received badge  Notable Question (source)
2012-09-06 01:15:57 -0500 received badge  Famous Question (source)
2012-09-06 01:15:57 -0500 received badge  Popular Question (source)
2012-09-06 01:15:57 -0500 received badge  Notable Question (source)
2012-08-26 21:18:33 -0500 received badge  Famous Question (source)
2012-08-26 21:18:33 -0500 received badge  Notable Question (source)
2012-08-24 02:41:19 -0500 received badge  Notable Question (source)
2012-08-24 02:41:19 -0500 received badge  Famous Question (source)
2012-08-20 01:28:01 -0500 received badge  Notable Question (source)
2012-08-20 01:28:01 -0500 received badge  Famous Question (source)
2012-08-03 12:20:00 -0500 commented answer why openni packages are outdated?

Thanks jbohren!, in addition to the above I had to re install the drivers. (similarly to this question: