cosmic_cow's profile - activity

Ubuntu 12.04, Fuerte

I'm doing some stuff with the Robonaut (r2) model in Gazebo. I'm using a couple of topics to get information about the world (specifically tf and model_states). The problem I'm having is when I go to initialize the listener:

rospy.init_node('listener', anonymous=True)

I'm using tf to get location information for parts of Robonaut (fingertips and whatnot). If this node initialization has already been run, when it hits this line for the second go-round, it breaks up the frame tree for the model, the robot goes limp, and I can no longer control it (or get useful information since most of the parent/child relationships have been broken). I've verified this by running

rosrun tf view_frames

before and after a second intialization and examining the output pdf. Many of the frames are simply gone, and you just end up with a bunch of individual two-element 'trees' (i.e. one parent node, one child).

I have no explanation for this behavior; my understanding is that ROS will just replace an old node if it gets initialized a second time. I could be very cautious in my code and ensure I only run this once in a main method or something, but since I've written separate classes and functions that retrieve information from topics, I'd like to be able to just check if it's been initialized and skip initialization if it has so that my code is more flexible and reusable. Is it possible to do this?

Thanks

Ubuntu 12.04 Fuerte

I'm trying to use 'rosservice call get_link_state ' or 'rosservice call gazebo/get_link_properties' to get information on Robonaut's positions in the world in Gazebo. The following show the results using either a valid or invalid link names with gazebo/get_link_properties:

colin@ubuntu:~$ rosservice call gazebo/get_link_properties /r2/right_index_distal
ERROR: service [/gazebo/get_link_properties] responded with an error:

colin@ubuntu:~$ rosservice call gazebo/get_link_properties /r2/rifgjdjg
ERROR: transport error completing service call: unable to receive data from sender, check sender's logs for details

get_link_state is a link in relation to something else (I just try 'world') and it gets the same "responded with an error:" message but, like the previous service call, without any useful information. Is there something I'm doing incorrectly?

I'm trying to model a simple hammer for use in Gazebo; I'm using ROS Fuerte in Ubuntu 12.04. It doesn't have to be terribly complicated, it's just to do some grasping stuff with the NASA Robonaut r2 model (which runs just fine). I've tried modeling a simple rectangle with a static joint to a cylinder in URDF, but I can't get anything to spawn. It either says it can't communicate or crashes Gazebo outright. I feel like I'm stumbling in the dark; there's precious little I can find for how to do object modeling for Gazebo, and any help would be greatly appreciated.