Well, I just figured out how to add an optical sensor without adding any moving mass. This is the Y axis I'm working on, which is carried by the X axis. If I home the X first, then I can use a fixed optical sensor to home the Y axis. It would not be possible to home Y unless X was already at its home position. I think that should be OK.
Neil On Sun, Jun 6, 2010 at 1:51 PM, Neil Baylis <neil.bay...@gmail.com> wrote: > Just wanted to point out that there are millions of inkjet printers and > plotters in operation right now that use this exact technique. It's > certainly practical. I think the reason they do it is to lower the cost. I > imagine it also improves reliability by eliminating failure-prone parts > (switches, connectors, etc). > > The reason I would do it is to lower the moving mass, as I'm attempting to > build a very agile machine, and every ounce counts. If it's too complicated > though, I'll rig up some optical sensor that can have low mass. On the other > axis, I already have a reflective optical sensor that adds no moving mass > and works well, but that's more difficult on this axis. > > Sam's point about the Integral term is important, and raises another > question: is it possible to alter the PID tuning parameters after the .ini > file has been read. I think the answer must be yes, because the calibration > tool in the GUI does this, but not having read the code yet, I don't know > how that works. But even assuming that's possible, I don't have a clear idea > of where I would need to hook into EMC to do what I want. > > Neil > > > On Sun, Jun 6, 2010 at 1:25 PM, Viesturs Lācis > <viesturs.la...@gmail.com>wrote: > >> Can You explain the reason, why would You want to do it this way? I >> think that such approach is breaking machine, it creates unnecesary >> loads and stresses to the construction of machine and simple switches >> are cheap and wiring them is easy. I think that it is trying to >> reinvent the wheel in some painful way. >> No offense, just my personal opinion :)) >> >> Viesturs >> >> 2010/6/6 sam sokolik <sa...@empirescreen.com>: >> > I could maybe see monitoring following error... When the servo hit the >> > limit - the error would increase. You could then use some logic that >> > says when the following error reaches a certain amount - trip the >> > 'virtual' limit switch. Maybe.. I could see lots of issues and as >> > gene says - you would want to limit the output to the servos. If you >> > have any I (in the pid) the pid loop will 'wind up' pretty quick sending >> > the servos to maximum. >> > >> > Big picture it seems possible... :) (but I am just thinking out loud) >> > >> > sam >> > >> > On 6/6/2010 11:09 AM, Neil Baylis wrote: >> >> Many printers& plotters do not use limit switches. Instead, they move >> the >> >> print head slowly towards the end stop until the motor stalls, and then >> back >> >> off from that point a certain distance and that's the home position or >> soft >> >> limit. >> >> >> >> What, roughly, do I need to do with EMC to get this behavior? >> >> >> >> Neil >> >> >> ------------------------------------------------------------------------------ >> >> ThinkGeek and WIRED's GeekDad team up for the Ultimate >> >> GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the >> >> lucky parental unit. See the prize list and enter to win: >> >> http://p.sf.net/sfu/thinkgeek-promo >> >> _______________________________________________ >> >> Emc-users mailing list >> >> Emc-users@lists.sourceforge.net >> >> https://lists.sourceforge.net/lists/listinfo/emc-users >> >> >> >> >> > >> > >> > >> ------------------------------------------------------------------------------ >> > ThinkGeek and WIRED's GeekDad team up for the Ultimate >> > GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the >> > lucky parental unit. See the prize list and enter to win: >> > http://p.sf.net/sfu/thinkgeek-promo >> > _______________________________________________ >> > Emc-users mailing list >> > Emc-users@lists.sourceforge.net >> > https://lists.sourceforge.net/lists/listinfo/emc-users >> > >> >> >> ------------------------------------------------------------------------------ >> ThinkGeek and WIRED's GeekDad team up for the Ultimate >> GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the >> lucky parental unit. See the prize list and enter to win: >> http://p.sf.net/sfu/thinkgeek-promo >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > > > > -- > http://www.pixpopuli.com > -- http://www.pixpopuli.com ------------------------------------------------------------------------------ ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
