OK so here is what is required. The "joint action server" gets messages for up to 6 axis. The messages contain the velocities for each joint. Realistically it will not get more than abut 20 of these per second. Other types of messages are per joint acceleration limits and transformation matrixes. But this pulse generator lives at the "far end" of the chain and will only see the velocity commands. If there are more than 6-axis then two controlers are used.
Yes, it does seem like if I used an Ethernet based Mesa card I could just send the right data down the cable. I assume the protocol is documented. I will download the user manual tonight. I like the idea of using commodity hardware, things like develoment boards because they are made in huge quantities and sell for under about $15. Arduino clones, ARM boards and even these: STM32F103C8T6-ARM-STM32 <https://www.ebay.com/itm/STM32F103C8T6-ARM-STM32-Minimum-System-Development-Board-Module-For-Arduino/162247218933?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D50426%26meid%3D869812b6a2e240b28ff3d84ebf620d99%26pid%3D100675%26rk%3D1%26rkt%3D15%26mehot%3Dpp%26sd%3D162247218933%26itm%3D162247218933&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3Abef2b426-3507-11e8-8cdb-74dbd1800d52%7Cparentrq%3A7d12b9451620ad7985deace6ffff4a43%7Ciid%3A1> The higher level planning is done on much more powerful machine. I'm using an 18-core Intel Xeon. As a separate issue the server sends back the state of the joints. It can do this any way it likes including open loop, that is just sending back where it "thinks" the stepper is based on counting steps. Or there could be sensors in the joints or even accelerometers and gyros. On Sat, Mar 31, 2018 at 9:06 AM, andy pugh <bodge...@gmail.com> wrote: > On 31 March 2018 at 16:52, Chris Albertson <albertson.ch...@gmail.com> > wrote: > > > 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 > > Motion commands do not have to come from G-code. You can send > canonical motion commands independently from motion, or you can simply > set the step-generator input pin to the required position (in > engineering units) > The Mesa step-generators have built-in acceleration and velocity limits. > halcmd setp hm2_5i25.0.stepgen.00.position 123.456 > But you don't even need to use LinuxCNC at all, you can just write the > required positions directly to PCI registers or transfer them down an > ethernet cable. > > And then there is Mesa's own motion controller. > http://store.mesanet.com/index.php?route=product/ > product&path=65&product_id=163 > Free with any FPGA card (according to that page) > > This was just posted to the forums, might be relevant: > https://forum.linuxcnc.org/49-basic-configuration/34295- > rdl2-arduino-command-line-stepper-testing-utility#108162 > > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is > designed for the especial use of mechanical geniuses, daredevils and > lunatics." > — George Fitch, Atlanta Constitution Newspaper, 1916 > > ------------------------------------------------------------ > ------------------ > 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
