Distributed CNC Motion Control - Revision history

Aidan Williamson: category: torch table

2014-06-13T15:25:18Z

category: torch table

← Older revision		Revision as of 15:25, 13 June 2014
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			{{Template:Category=Torch Table}}
	= Centralized Motion Control =		= Centralized Motion Control =

ChuckH: /* OSE Implementation */

2013-09-03T03:13:26Z

OSE Implementation

← Older revision		Revision as of 03:13, 3 September 2013
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	* [http://www.ros.org/wiki/ ROS] (robot operating system) framework [http://opensourceecology.org/wiki/Industrial_Robot/Research_Development#Other_2]		* [http://www.ros.org/wiki/ ROS] (robot operating system) framework [http://opensourceecology.org/wiki/Industrial_Robot/Research_Development#Other_2]
			* Shop-wide communications [http://wiki.ros.org/sig/Multimaster ROS Multimaster]
	* [http://www.orocos.org/ Orocos] realtime software in nodes if appropriate		* [http://www.orocos.org/ Orocos] realtime software in nodes if appropriate
	* Distributed motion commands as PVT (position, velocity, time) messages		* Distributed motion commands as PVT (position, velocity, time) messages

ChuckH: /* OSE Implementation */

2013-08-29T03:49:18Z

OSE Implementation

← Older revision		Revision as of 03:49, 29 August 2013
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	(Possible techniques, to be expanded)		(Possible techniques, to be expanded)

	* [http://www.ros.org/wiki/ ROS] (robot operating system) framework		* [http://www.ros.org/wiki/ ROS] (robot operating system) framework [http://opensourceecology.org/wiki/Industrial_Robot/Research_Development#Other_2]
	* [http://www.orocos.org/ Orocos] realtime software in nodes if appropriate		* [http://www.orocos.org/ Orocos] realtime software in nodes if appropriate
	* Distributed motion commands as PVT (position, velocity, time) messages		* Distributed motion commands as PVT (position, velocity, time) messages

ChuckH: /* OSE Implementation */

2013-08-13T07:16:06Z

OSE Implementation

← Older revision		Revision as of 07:16, 13 August 2013
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	* [http://www.ros.org/wiki/ ROS] (robot operating system) framework		* [http://www.ros.org/wiki/ ROS] (robot operating system) framework
	* [http://www.orocos.org/ Orocos] software in nodes if appropriate		* [http://www.orocos.org/ Orocos] realtime software in nodes if appropriate
	* Distributed motion commands as PVT (position, velocity, time) messages		* Distributed motion commands as PVT (position, velocity, time) messages
	** semantics: "starting where you are now, at your current instantaneous velocity, arrive at absolute position P at absolute time T, moving at instantaneous velocity V when you arrive"		** semantics: "starting where you are now, at your current instantaneous velocity, arrive at absolute position P at absolute time T, moving at instantaneous velocity V when you arrive"

ChuckH: /* OSE Implementation */

2013-08-13T07:15:48Z

OSE Implementation

← Older revision		Revision as of 07:15, 13 August 2013
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	* [http://www.ros.org/wiki/ ROS] (robot operating system) framework		* [http://www.ros.org/wiki/ ROS] (robot operating system) framework
			* [http://www.orocos.org/ Orocos] software in nodes if appropriate
	* Distributed motion commands as PVT (position, velocity, time) messages		* Distributed motion commands as PVT (position, velocity, time) messages
	** semantics: "starting where you are now, at your current instantaneous velocity, arrive at absolute position P at absolute time T, moving at instantaneous velocity V when you arrive"		** semantics: "starting where you are now, at your current instantaneous velocity, arrive at absolute position P at absolute time T, moving at instantaneous velocity V when you arrive"

ChuckH: /* Distributed Motion Control Concept */

2013-08-13T07:12:06Z

Distributed Motion Control Concept

← Older revision		Revision as of 07:12, 13 August 2013
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	= Distributed Motion Control Concept =		= Distributed Motion Control Concept =

	Distributed motion control supports a modular design process in which new functions can be added with additional loosely-coupled processors, rather than being knitted into a single program. Modularity is appropriate for OSE designs.		Distributed motion control, in contrast to centralized control, supports a modular design process in which new functions can be added with additional loosely-coupled processors, rather than being knitted into a single program. Modularity is appropriate for OSE designs.

ChuckH: /* OSE Implementation */

2013-08-13T07:09:14Z

OSE Implementation

← Older revision		Revision as of 07:09, 13 August 2013
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	= OSE Implementation =		= OSE Implementation =

	~~We intend~~ to implement distributed CNC machine control in accordance with OSE principles.		How to implement distributed CNC machine control in accordance with OSE principles...

	(Possible techniques, to be expanded)		(Possible techniques, to be expanded)

ChuckH: /* Trajectory command distribution */

2013-08-13T07:08:12Z

Trajectory command distribution

← Older revision		Revision as of 07:08, 13 August 2013
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	== Trajectory command distribution ==		== Trajectory command distribution ==

	CNC machines are most commonly programmed in ''G-code''. Each "motion" line of a G-code program specifies a coordinated move of the entire machine (3, 4, or more axes), telling it to arrive at a target endpoint following a particular trajectory. Often the trajectory is simply a straight line, but there are standard G-code commands for circles, partial arcs, and helices.		CNC machines are most commonly programmed in ''[[G-code]]''. Each "motion" line of a G-code program specifies a coordinated move of the entire machine (3, 4, or more axes), telling it to arrive at a target endpoint following a particular trajectory. Often the trajectory is simply a straight line, but there are standard G-code commands for circles, partial arcs, and helices.

	In a distributed system, where (for example) one processor handles X,Y,Z motions of a milling machine frame and a different processor handles a "4th axis" rotary table, it is not enough to simply send the target endpoint information to the rotary-table processor. It must also know when to start moving, how fast to accelerate, and a few other parameters in order to assure its movement is precisely coordinated with the machine frame at every point in the move. The process of breaking up a single G-code motion command into individual axis commands for distribution to loosely-coupled motion processors can become somewhat tricky and bandwidth-intensive. Furthermore, there is no "industry standard" format for these distributed commands that is comparable to G-code itself.		In a distributed system, where (for example) one processor handles X,Y,Z motions of a milling machine frame and a different processor handles a "4th axis" rotary table, it is not enough to simply send the target endpoint information to the rotary-table processor. It must also know when to start moving, how fast to accelerate, and a few other parameters in order to assure its movement is precisely coordinated with the machine frame at every point in the move. The process of breaking up a single G-code motion command into individual axis commands for distribution to loosely-coupled motion processors can become somewhat tricky and bandwidth-intensive. Furthermore, there is no "industry standard" format for these distributed commands that is comparable to G-code itself.

ChuckH: /* Centralized Motion Control */

2013-08-13T07:05:29Z

Centralized Motion Control

← Older revision		Revision as of 07:05, 13 August 2013
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	= Centralized Motion Control =		= Centralized Motion Control =

	CNC tools like the [[CNC Torch Table]], [[HydraFabber]], etc. require precision synchronized multi-axis movement. Typically a central controller, such as [[CoolRAMPS]] or [[~~Open_Source_Stepper_Controller~~]], has the responsibility of generating synchronized step-and-direction commands on three axes, with rates up to about 20,000 pulses per second. As more axes and auxiliary functions are added to the machine, the hardware resources and software coordination required to maintain "hard real time" performance in the single central controller become a bottleneck.		CNC tools like the [[CNC Torch Table]], [[HydraFabber]], etc. require precision synchronized multi-axis movement. Typically a central controller, such as [[CoolRAMPS]] or [[Steppernug]], has the responsibility of generating synchronized step-and-direction commands on three axes, with rates up to about 20,000 pulses per second. As more axes and auxiliary functions are added to the machine, the hardware resources and software coordination required to maintain "hard real time" performance in the single central controller become a bottleneck.

	= Distributed Motion Control Concept =		= Distributed Motion Control Concept =

ChuckH: /* OSE Implementation */

2013-08-13T07:03:43Z

OSE Implementation

← Older revision		Revision as of 07:03, 13 August 2013
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	** usually implies cubic-spline interpolator		** usually implies cubic-spline interpolator
	* Lookahead trajectory planner to process G-code (see grbl? [http://wiki.linuxcnc.org/cgi-bin/wiki.pl?List_Of_CAM_References LinuxCNC CAM references]?)		* Lookahead trajectory planner to process G-code (see grbl? [http://wiki.linuxcnc.org/cgi-bin/wiki.pl?List_Of_CAM_References LinuxCNC CAM references]?)
	** convert arc G-codes to PVT		** convert line and arc G-codes to PVT
	** coalesce adjacent commands if accuracy ~~is maintained~~ (~~reducing~~ PVT command rate)		** coalesce adjacent commands if accuracy isn't compromised (reduces PVT command rate)