[ros-users] rospy and simulation time

[Patrick Doyle]

Hi Ken,
Thanks for the quick reply.  Even as I pasted the code into my email,
I was thinking "Gee, isn't there supposed to be the name of the code
somewhere in here?".  Oh well, they say that memory is the second
thing to go...

I added the following line:

rospy.init_node('test')

immediately following the the 2 import statements and ran the code again.

With pr2_empty_world.launch running, I ran the code.  It exited at
(simulated) t=5.

Then, when I ran it again, it exited immediately.... each time.
(Now _this_ is similar to the timeout issue I mentioned earler.)


Is that to be expected?  Did I miss something else?

--wpd


On Thu, Nov 4, 2010 at 5:18 PM, Ken Conley <kwc at willowgarage.com> wrote:
> Hi Patrick,
>
> rospy does obey simulation time, but you have to initialize a node
> (i.e. you need an init_node()). Only nodes can obey simulated time
> because you have to subscribe to a topic.
>
>  - Ken
>
> On Thu, Nov 4, 2010 at 1:58 PM, Patrick Doyle <wpdster at gmail.com> wrote:
>> Is it possible to make rospy use simulation time instead of wall-clock time?
>>
>> Consider the following program:
>>
>> #!/usr/bin/env python
>> import roslib; roslib.load_manifest('wpdtb')
>> import rospy
>>
>> print "About to sleep for 5 seconds..."
>> rospy.sleep(5)
>> print "done"
>>
>> I run this on a slow machine (i.e. one in which simulation time runs
>> slower than real time).  If I start up roscore in one window, and run
>> this in a second window, it exits after 5 seconds as expected.  If
>> instead I launch the PR2 simulator in one window:
>>
>> $ roslaunch pr2_gazabo pr2_empty_world.launch
>>
>> and run this in a second window, it still exits after about 5
>> wallclock seconds.  I thought the /use_sim_time parameter would have
>> made this wait 5 simulated seconds.
>>
>> I have similar problems with rospy.rate().  And I've given up all
>> together passing a Duration() timeout to wait_for_service().
>>
>> --wpd
>> _______________________________________________
>> ros-users mailing list
>> ros-users at code.ros.org
>> https://code.ros.org/mailman/listinfo/ros-users
>>
> _______________________________________________
> ros-users mailing list
> ros-users at code.ros.org
> https://code.ros.org/mailman/listinfo/ros-users
>