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Programming Robotics Technology Hardware

Needed: A LAMP Stack For Robotics 65

Posted by timothy
from the help-wanted-apply-through-the-usb-port dept.
waderoush writes "If you visit Menlo Park, CA-based Willow Garage, you'll meet a $400,000 humanoid robot called PR2 that has stereo vision, a pair of dextrous arms, and enough smarts to roam the building indepedently and even plug itself into the wall when it needs to recharge. But in a sense, PR2 is just a demo. The real action at Willow Garage is around ROS, the Robot Operating System, a free meta-operating system that's already being used by hundreds of roboticists around the world and may soon be handed over to an independent foundation analogous to the Apache Software Foundation. Brian Gerkey, Willow Garage's head of open source development, says 'What we need is a LAMP stack for robotics,' and hopes that ROS will jumpstart innovation in robotics in the same way Linux and other free software components provided the foundation for the Internet boom. Today's roboticists 'have to come at the problem with a very deep expertise in all aspects of robotics, from state estimation to planning to perception, which automatically limits the number of people capable of building new things,' Gerkey says. 'But by providing a basic toolset analogous to the LAMP stack, we can get to a point where all you need to know is how to write code and what you want your robot to do.'"
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Needed: A LAMP Stack For Robotics

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  • Linuxcnc + RTAI (Score:5, Interesting)

    by LuxuryYacht (229372) on Thursday March 29, 2012 @09:07AM (#39508851) Homepage

    Much of this is already in LinuxCNC
    http://www.linuxcnc.org/ [linuxcnc.org]

    It's mostly used by developers to control CNC machines but it also includes support for non-Cartesian motion systems provided via custom kinematics modules. Available architectures include hexapods (Stewart platforms and similar concepts) and systems with rotary joints to provide motion such as PUMA or SCARA robots.

    http://linuxcnc.org/docs/html/man/man9/kins.9.html [linuxcnc.org]
    http://linuxcnc.org/docs/html/motion_kinematics.html [linuxcnc.org]

    We've use it to control some pretty complex robotic systems.

  • There is - JAUS (Score:5, Interesting)

    by Animats (122034) on Thursday March 29, 2012 @09:56AM (#39509727) Homepage

    There is such a stack: Open JAUS. [openjaus.com] JAUS is the Joint Architecture for Unmanned Systems used by many military robotic and unmanned systems. It's somewhat dated, and has a more open-loop approach more suited to teleoperators than fully autonomous systems.

    Dealing with the time constraints in robotics rules out some of the approaches used in other software. Microsoft's Robotics Studio [microsoft.com] was built on a web-like approach, and it was a flop. Game programs tend to be tied to the display refresh rate, which isn't helpful in robotics. In robotic systems, there may be several subsystems with their own cyclic rate and processing delay, and they need to talk to each other. The inputs which have processing delays, like vision systems, produce outputs which represent the situation at some time in the past. Updates to the world model based on multiple sensors must all be synchronized to the time of the observation, not the time the data became available. This matters when you're moving fast. For slow robots, not so much. Many research robots are slow and pause a lot because they don't do this. That was the norm a few years ago, but it's not any more.

    Robotic systems tend to need hard real time control. That control can be quite complex, not just a simple servo loop. Inside the more advanced and agile robots, like BigDog, you tend to find QNX, not Linux. (Typical test for a hard real-time OS [tamu.edu]: hook up a square wave oscillator to an input, and a scope to an output. Put a high-priority program in the system which turns on the output when the input comes on. Watch the input to output delay on the scope. Load up the system with lower-priority tasks. If the input to output delay is ever substantially longer, (more than a few microseconds) the system is not hard real time. The "real time" variants of Linux have trouble getting down to 1ms, and 10ms of jitter is observed. In hard real time systems, 10us is more like it. Servo control in BigDog executes every 1ms, balance every 10ms.) However, as CPUs get faster, the limitations of Linux have become less of an issue.

The most exciting phrase to hear in science, the one that heralds new discoveries, is not "Eureka!" (I found it!) but "That's funny ..." -- Isaac Asimov

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