On Fri, Mar 30, 2018 at 8:20 PM, Gene Heskett <ghesk...@shentel.net> wrote: > On Friday 30 March 2018 20:34:52 Chris Albertson wrote: >
> Just one question? Can you build this for less than you can buy it from > Mesa? Or Pico? If you time is worth a buck an hour, its a slim chance > of yes. Very slim. Otherwise get it from a supplier that supports us. The arm is not going to use MK or LCNC. I'm using that on the machine tools but this arm needs more flexibility than offered by any of the machine tool controllers. This is the high level control software I'll use if you are interested: https://moveit.ros.org/documentation/concepts/ This pulse generator will be part of the blue box called "robot controllers" The trouble with Mesa in this case is that I'd have to write a whole bunch of FPGA code to make it into what they call a "joint trajectory action server" I thought about using G-code for the robots but they need to do things like notice you have set a beer can on the table then plan motion around the can. This has to happen in real time, you can't code the motion in advance There is not much to build. A need to buy an ARM-M based board and than add a buffer chip to convert 3.3 volts to 5 volt TTL. Cot should be <$20 total but if one of these works I can build it for under $5 .ebay.com/itm/STM32F103C8T6 <https://www.ebay.com/itm/STM32F103C8T6-ARM-STM32-Minimum-System-Development-Board-Module-For-Arduino/162247218933?epid=532038167&hash=item25c6b016f5:g:ZXMAAOSwA3dYCJJd> Back to steps per second. If the carriage moves at 90ipm, that is 38 mm/sec, with a 5mm screw that means 8 turns per second. or 1600 full steps per second but perhaps you are doing 1/4 steps so it is 6400 steps/second. Your machine with software steps is doing about 8X slower? with no more then 800 steps/second. It looks like there is no need for more than 10K steps per second and half that might work. About jitter, if 3% of the period reduces torque and the fastest rate is 10KHz then only 3 uSec of jitter can be tolerated. > How many motors in your arm? The 7i90HD at less than $70, + 3 7i42TA's > at about 45$ ea, about $200, can handle 8 steppers. And have plenty of > gpio left to do lots of other things. Limited only by your imagination. > > -- > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > Genes Web page <http://geneslinuxbox.net:6309/gene> > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
