I think this could be done as a geared solution, if you could work from a phase locked (to 50hz) clock at some higher rate, and use that as the encoder signal, and the 50hz as a trigger to g76 with suitable parameters it would then be synchronised and have a flyback (gate the laser off then), or use g33 or play with the gearing that can be used with hobbing, see http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Hobbing (add any logic to suit).
Dave Caroline On 22/04/2014, Florian Rist <fr...@fs.tum.de> wrote: > Hi, > I'm facing a slightly unusual problem and before I head forward into the > wrong direction I'd like to hear what you think about it: > > I have to pan a laser scanner (a single rotary axis), so I thought about > using a BLDC (which I happen to have already), a MESA 7I39 BLDC > controller and a BeagleBone Black. > > So, first question: Can I hook up the 7I39 to a BeagleBone Black. Well > of course I can, but is this somehow supported already, so that it is > simple to do? Any other driver suggestions? > > The bigger problem is that I need to synchronise the motion with a high > 'frequency trigger' signal (about 50 Hz). The motion pattern needed is > cyclic an has to look something like his: > > 0. move to home position (0°) > 1. wait for low frequency trigger, a hardware or a software signal > 2. within say 10° accelerate and synchronises to the 50Hz trigger > so that the 10° position is reached 20ms after the last trigger > and at a given speed (specified in degree per trigger pulse, > not in seconds as the pulse rate of the trigger may change slightly) > 3. keep on moving at the give speed (in sync with the trigger) for 100° > 4. decelerate an move to a safe position > > 5. goto 1. and repeat the process in reverse direction > > > How could I use LiuxCNC/Machinekit to synchronise the motion to the > external trigger signal and ensure a specific position is reached at a > specific speed in sync with the trigger? > > The reason why I want this is to make sure the scanner captures lines at > the same angular positions. The trigger comes from the scanner an > indicates the start of a line capture. > > Unfortunately the scan process can not be trigger externally, this would > be much easier, but I only get a signal each time a scan line starts. > > Hmm, well. What do you think. Is LiuxCNC right for the job or not. > > > See you > Flo > > ------------------------------------------------------------------------------ > Start Your Social Network Today - Download eXo Platform > Build your Enterprise Intranet with eXo Platform Software > Java Based Open Source Intranet - Social, Extensible, Cloud Ready > Get Started Now And Turn Your Intranet Into A Collaboration Platform > http://p.sf.net/sfu/ExoPlatform > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Start Your Social Network Today - Download eXo Platform Build your Enterprise Intranet with eXo Platform Software Java Based Open Source Intranet - Social, Extensible, Cloud Ready Get Started Now And Turn Your Intranet Into A Collaboration Platform http://p.sf.net/sfu/ExoPlatform _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
