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How pr2_mechanism to use hard real-time mechanism?

asked 2011-09-30 03:42:20 -0600

sam gravatar image

pr2_mechanism doc says: The pr2_mechanism stack contains the infrastructure to control the PR2 robot in a hard realtime control loop.

When I using normal ubuntu not linux-rt,does pr2_mechanism will also make sure it can use hard real-time mechanism?

Or should I install linux-rt and install ROS on that kernel?

Thank you~

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answered 2011-09-30 04:53:52 -0600

joq gravatar image

Vanilla Linux kernels have provided good real-time performance for many years. For most robotics applications, the generic Ubuntu kernel should work fine.

If you observe performance problems with your robot running your specific mix of software, there are several kernel options you can try.

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Thank you~ But when I using normal ubuntu not linux-rt,does pr2_mechanism will also make sure it can use hard real-time mechanism? Or will it just no hard rt functionalities?
sam gravatar imagesam ( 2011-10-19 14:32:11 -0600 )edit
The vanilla Ubuntu kernel provides soft realtime, which is good enough for most robotics. It supports POSIX realtime scheduling. If you believe you need harder guarantees, you should first measure the jitter while running your actual hardware and software.
joq gravatar imagejoq ( 2011-10-19 15:32:36 -0600 )edit
Thank you for these information. And what's the answer of my question? Do pr2_mechanism have that ability or not? Yes or no?
sam gravatar imagesam ( 2011-10-20 04:19:03 -0600 )edit
I do not know the internal implementation of pr2_mechanism. Since it says it supports hard real-time, I suppose it must use real-time scheduling.
joq gravatar imagejoq ( 2011-10-20 04:37:17 -0600 )edit
Yes, pr2_mechanism allows you to run controllers in hard realtime.
Wim gravatar imageWim ( 2011-11-03 08:21:48 -0600 )edit

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Asked: 2011-09-30 03:42:20 -0600

Seen: 347 times

Last updated: Sep 30 '11