[Emc-users] Stepper Musings
Prompted by a query on the forums on the age-old question of using encoders with steppers, I started wondering about wierd and wonderful ways to make it work. The issue is that steppers just don't have the right characterstics to work in a servo loop, as trying to run them harder to recover a missed step will probably make things worse. So, I pondered the idea of using a PID with a unity feedforward term and a negative PGain, so that as long as there is no error the system works as a normal stepper setup, but if there is a missed step then the error * Pgain would back the velocity off a bit. I think the drawback of this is that there is nothing to claw the error back, though perhaps a slow I with a higher limit than the P might do it. Probably a more promising idea is to not attempt to recover position immediately, but to link the output of a PID to the motion.adaptive-feed pin, so that any missed steps result in the system backing-off the feedrate.You would probably want a slow-I PID as a separate component to claw back the missed steps once the feedrate has slowed enough. Any thoughts? -- atp Torque wrenches are for the obedience of fools and the guidance of wise men -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Stepper Musings
2010/11/29 andy pugh bodge...@gmail.com: You would probably want a slow-I PID as a separate component to claw back the missed steps once the feedrate has slowed enough. Any thoughts? If I understand correctly this concept, then in case of major losing of steps (motor stalled) following error would be triggered. It seems like a very promising idea to me! How difficult is the implementation part? Viesturs -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Stepper Musings
Unfortunately when a stepper looses synchronisation, one needs to 'stop' the motor for the poles to realign and then you can move the motor again. I cannot see how a motor travelling at a velocity near its maximum capable velocity can loose just a single step with out stopping altogether. Steppers with encoders could benefit when there are lots of short reversals, and a step (or many) might be lost when the motor cannot accelerate and decelerate due quickly enough. Your workpiece might still show evidence of missed steps but it is likely that it won't be ruined as the cutter will be machine away 'less' when it stops on a reversal. Clear as mud? I think (but I'm not sure) that the algorithm used on the Mesa card is a hardware step generator and that the delta frequency (commanded frequency versus the actual) is proportional to the error, as the error increases, the frequency can be increased to compensate. The following error will stop the machine if it becomes too great. The PID loop controls the actual frequency proportionally to the error. Greg - Original Message - From: andy pugh bodge...@gmail.com To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Sent: Monday, November 29, 2010 4:07 PM Subject: [Emc-users] Stepper Musings Prompted by a query on the forums on the age-old question of using encoders with steppers, I started wondering about wierd and wonderful ways to make it work. The issue is that steppers just don't have the right characterstics to work in a servo loop, as trying to run them harder to recover a missed step will probably make things worse. So, I pondered the idea of using a PID with a unity feedforward term and a negative PGain, so that as long as there is no error the system works as a normal stepper setup, but if there is a missed step then the error * Pgain would back the velocity off a bit. I think the drawback of this is that there is nothing to claw the error back, though perhaps a slow I with a higher limit than the P might do it. Probably a more promising idea is to not attempt to recover position immediately, but to link the output of a PID to the motion.adaptive-feed pin, so that any missed steps result in the system backing-off the feedrate.You would probably want a slow-I PID as a separate component to claw back the missed steps once the feedrate has slowed enough. Any thoughts? -- atp Torque wrenches are for the obedience of fools and the guidance of wise men -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.449 / Virus Database: 271.1.1/3275 - Release Date: 11/23/10 19:34:00 -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Stepper Musings
On 29 November 2010 15:20, Belli Button be...@iafrica.com wrote: Unfortunately when a stepper looses synchronisation, one needs to 'stop' the motor for the poles to realign and then you can move the motor again. I cannot see how a motor travelling at a velocity near its maximum capable velocity can loose just a single step with out stopping altogether. I think you are right about that, and tripping f-error is all you will get there (which is better than nothing). Where the scheme might work is in slow overload situations (I have heard my lathe missing steps on very slow feeds when trying to push too big a drill). In that case slowing the feed and recovering the steps might work (in the case I mentioned the drill did keep feeding, but the hole depth came out wrong and machine position was lost. -- atp Torque wrenches are for the obedience of fools and the guidance of wise men -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] OT: Coil Tying
Do you mean lacing cable harness? if so http://www.dairiki.org/hammond/cable-lacing-howto/ Dave Caroline On Mon, Nov 29, 2010 at 5:05 PM, Kirk Wallace kwall...@wallacecompany.com wrote: Does anyone have a link covering the old style of bunch tying wire coils? -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] OT: Coil Tying
or did you mean that wonderful african welder transformer that was posted recently, it had a lot of string in it especially the stack of bent E frames in the center tom3p On Mon, Nov 29, 2010 at 11:05 AM, Kirk Wallace kwall...@wallacecompany.com wrote: Does anyone have a link covering the old style of bunch tying wire coils? -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA or did you mean that wonderful african welder transformer that was posted recently? it had a lot of string in it especially the stack of bent E frames in the center and the copper coils wrapped around them but maybe the people using that technique dont have websites 'links' :) tom3p -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] Compile EMC2
Hello, folks! I have a question about compiling EMC2. I have EMC 2.4.3 installed on my PC in a regular way. I want to implement some changes in Axis GUI, so I got the source of EMC2 through GIT and did checkout v2.4.3. I have changed the /home/vie/emc2-dev/src/emc/usr_intf/axis/scripts/axis.py and now I want to compile EMC so that these changes would be reflected in the regular installation of EMC. If I will run these commands: $ cd src $ ./autogen.sh $ ./configure $ make EMC will be compiled with the default run in place option and I will have 2 separate EMCs. At least that is what happened the previous time I tried it. What am I missing here and how do I compile the changes of /home/vie/emc2-dev/src/emc/usr_intf/axis/scripts/axis.py into regular installation of EMC? Thank You in advance! Viesturs -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Compile EMC2
I think I've read here some weeks ago python is interpreted, not compiled, so you sould have nothing special to do to see your changes in axis, just quit and relaunch it. - Viesturs Lācis viesturs.la...@gmail.com a écrit : Hello, folks! I have a question about compiling EMC2. I have EMC 2.4.3 installed on my PC in a regular way. I want to implement some changes in Axis GUI, so I got the source of EMC2 through GIT and did checkout v2.4.3. I have changed the /home/vie/emc2-dev/src/emc/usr_intf/axis/scripts/axis.py and now I want to compile EMC so that these changes would be reflected in the regular installation of EMC. If I will run these commands: $ cd src $ ./autogen.sh $ ./configure $ make EMC will be compiled with the default run in place option and I will have 2 separate EMCs. At least that is what happened the previous time I tried it. What am I missing here and how do I compile the changes of /home/vie/emc2-dev/src/emc/usr_intf/axis/scripts/axis.py into regular installation of EMC? Thank You in advance! Viesturs -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- (\__/) (='.'=) Ceci est un petit lapin. Copiez/collez-le dans ()_() votre signature pour l'aider à dominer le monde -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Need help with USC servo mode.
Jon; I stumbled into the solution, responses below. On Sat, Nov 27, 2010 at 12:39 AM, Jon Elson el...@pico-systems.com wrote: Don Stanley wrote: Hi Jon and All; My configuration is: -D510MO computer -Ubuntu 10.04 Live Disk -EMC2 2.4.5 -USC with univstep reconfigured for mill. The USC works fine in non servo mode, (Switches down). When I switch to servo (switches up) none of the three servo axis will move. OK, this is not ALL switches up. Switch # 1 set to ON changes the first axis to be closed-loop. Switch #2 affect the second axis in this way, etc. Now, when you move the motor manually, you should see the DRO position display change on the screen. If it doesn't, then something is wrong with the encoder connection, probably. Note that switches 4-7 change the step/direction output to phase output. if you feed this to a microstepping drive step/dir, the moves would be constantly changing direction every 2nd (micro) step, and might appear to not be moving at all. I'm guessing that may be what you have done. If not, then we will have to investigate further. Other than making sure INPUT_SCALE has the right sign and scale factor for your encoder, nothing in your .ini file needs to change. (I believe I previously told you that input scale and output scale need to be the same. I think that's wrong, OUTPUT_SCALE needs to be either +1.0 or -1.0, whichever When the OUTPUT_SCALE is set to +1.0 I was getting 1 step output for each inch of travel. That was actually .04 inches of movement for 1 inch movement shown on the axis display. My drives need 125000 steps per inch of travel (25 steps on the knee). When I set the OUTPUT_SCALE to 125000 move starts became very rough and stalled the motors. I had to change the MAX_ACCELERATION = from 20 to 1 (or less) to get a top speed of 40 inches per minute (as opposed to 60 ipm in non servo mode). Does all this compute with you? Thanks Don sign doesn't cause a servo runaway.) Sorry about the confusion on this, not too many people use this feature. But, it does work, I use it to test out my Gecko interface board. On a 3-axis closed-loop machine, you want switches 1-3 on, 4-9 off, and 10 on for the first USC board. Jon -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] OT: Coil Tying
On Mon, 2010-11-29 at 17:18 +, Dave Caroline wrote: Do you mean lacing cable harness? if so http://www.dairiki.org/hammond/cable-lacing-howto/ Dave Caroline Thank you. That's what I had in mind. I thought it was more complicated, but I guess knot. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Stepper Musings
Date: Mon, 29 Nov 2010 15:54:22 + From: andy pugh bodge...@gmail.com Subject: Re: [Emc-users] Stepper Musings To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net On 29 November 2010 15:20, Belli Button be...@iafrica.com wrote: Unfortunately when a stepper looses synchronisation, one needs to 'stop' the motor for the poles to realign and then you can move the motor again. ?I cannot see how a motor travelling at a velocity near its maximum capable velocity can loose just a single step with out stopping altogether. I think you are right about that, and tripping f-error is all you will get there (which is better than nothing). Where the scheme might work is in slow overload situations (I have heard my lathe missing steps on very slow feeds when trying to push too big a drill). In that case slowing the feed and recovering the steps might work (in the case I mentioned the drill did keep feeding, but the hole depth came out wrong and machine position was lost. At first I was not really big on this but the more I think about it, the more I like it. I play with small, benchtop size machines, where inexpensive steppers and drives generally work well and cost half or less of what servos would. A pseudo-servo mechanism that simply tripped a fault when something bad started to happen would provide most if not all of the benefit that true servos would, at much less cost. It's not magic and won't make the machine more precise, but it would make it more fault-tolerant and that seems significant. It would also be a unique competitive edge that could bring a lot of users over to EMC2. Is this something that could be done just by wiring a few ~$50 encoders into a parport, or would you need more specialized IO hardware? -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] OT: Coil Tying
On Mon, 2010-11-29 at 11:32 -0800, Kirk Wallace wrote: On Mon, 2010-11-29 at 17:18 +, Dave Caroline wrote: Do you mean lacing cable harness? if so http://www.dairiki.org/hammond/cable-lacing-howto/ Dave Caroline Thank you. That's what I had in mind. I thought it was more complicated, but I guess knot. Getting the correct keywords returns a lot better results. Thanks again. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] OT: Coil Tying
On 29 November 2010 19:32, Kirk Wallace kwall...@wallacecompany.com wrote: Thank you. That's what I had in mind. I thought it was more complicated, but I guess knot. My EMC2 control box: http://picasaweb.google.com/bodgesoc/Gibbs#5438923441932523602 Looks like I guessed the right knot :-) -- atp Torque wrenches are for the obedience of fools and the guidance of wise men -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Stepper Musings
On Mon, 2010-11-29 at 14:43 -0500, Colin Kingsbury wrote: ... snip It's not magic and won't make the machine more precise, but it would make it more fault-tolerant and that seems significant. Maybe not tolerant, but it's nice to get a warning when a step or two are missed and otherwise is not obvious. ... snip Is this something that could be done just by wiring a few ~$50 encoders into a parport, or would you need more specialized IO hardware? The only problem I can think of is the parallel port speed limit. If one has high resolution encoders or fast axes, the encoder pulses can swamp the parport. The fix here is to go to a hardware counter. The least expensive that works I think is the Mesa 7i43P, which has other advantages too. But the cost adds up when one starts to tack on an improvement here and there. I would tend to make sure that the motors, pulleys, drivers and power supply are up to snuff to begin with. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] OT: Coil Tying
On 11/29/2010 2:53 PM, andy pugh wrote: On 29 November 2010 19:32, Kirk Wallacekwall...@wallacecompany.com wrote: Thank you. That's what I had in mind. I thought it was more complicated, but I guess knot. My EMC2 control box: http://picasaweb.google.com/bodgesoc/Gibbs#5438923441932523602 Looks like I guessed the right knot :-) A thing of beauty is a joy forever, Andy. Thanks for sharing. But...what's up with photo 54 of 56? Looks like there's a war story waiting to be told about that one. Regards, Kent -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] OT: Coil Tying
On 29 November 2010 21:33, Kent A. Reed knbr...@erols.com wrote: But...what's up with photo 54 of 56? Looks like there's a war story waiting to be told about that one. That's what I found when my cooker stopped working. A 3kW (13A) cooker wired though 1mm2 (7.5A) wire on a dedicated circuit with a 40A breaker. The earth wire on the rear side was loose, and fell out, Not that that matters as on the front side it was clamped to the insulation not the conductor anyway. You will also note that the neutral wire is not actually clamped in the (oversize) terminal block, but is actually loosely wedged down the side. All in all, I consider myself lucky to still have a house rather than a pile of cinders. -- atp Torque wrenches are for the obedience of fools and the guidance of wise men -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] OT: Coil Tying
On 11/29/2010 4:48 PM, andy pugh wrote: On 29 November 2010 21:33, Kent A. Reedknbr...@erols.com wrote: But...what's up with photo 54 of 56? Looks like there's a war story waiting to be told about that one. That's what I found when my cooker stopped working. A 3kW (13A) cooker wired though 1mm2 (7.5A) wire on a dedicated circuit with a 40A breaker. The earth wire on the rear side was loose, and fell out, Not that that matters as on the front side it was clamped to the insulation not the conductor anyway. You will also note that the neutral wire is not actually clamped in the (oversize) terminal block, but is actually loosely wedged down the side. All in all, I consider myself lucky to still have a house rather than a pile of cinders. To quote a colo(u)rful Aussie friend of mine, too right! The houses in the area we moved into when we came east were built in the early 1970s at a time when building codes were allowing the use of alumin(i)um wire in place of expensive copper wire. By dumb luck we chose to buy a home that had been properly wired, but not everyone was so lucky. Because of their current draw, cookers/stoves/ovens were a particular problem as aging, oxidized connections began to overheat. Then the heating/cooling cycles at the connections accelerated the problem by loosening up the screw connections. I personally know only one couple who have experienced a house fire, but I wouldn't wish it on my worst enemy. Regards, Kent -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Compile EMC2
First off, while we don't intend for there to be anything secret about building emc2 packages on Ubuntu 10.04 or 8.04, I still recommend that users who build their own use run-in-place. This is the easiest way to build your own version, the fastest to rebuild for small modifications, and it will never conflict with a packaged version. If there's some annoyance of run-in-place, perhaps we should talk about that. For instance, some users have been frustrated that with run-in-place there are no Applications entries by default. But in current versions you can create menu entries for a RIP EMC2 with make install-menus. I think this is undocumented so far, which is unfortunate, but the capability is there. Anyway, If you are on a version of Ubuntu that we build packages for, then you can build a .deb package of emc2 and then install it. Starting in the top director of a pristine copy of the emc2 source tree (not one where you've already built run-in-place), here are the steps to build a package: debian/update-dch-from-git # update debian/changelog from git history # (so it's best if you've git commited your # own local changes so they're listed in # changelog) # and then debian/configure -r# generate debian files for running kernel # or debian/configure sim # generate debian files for no-realtime # finally dpkg-buildpackage -B -ub If the dpkg-buildpackage step prompts you to install packages, then do so and run that step again. (dpkg-buildpackage builds the pdf documentation, which pulls in a lot of extra packages that are not necessary for an RIP build that doesn't build documentation. There are no plans to change this or make it optional. On Ubuntu 10.04, remember to install these packages with --no-install-recommends to reduce the number of extra packages to a minimum.) This will generate debian packages (*.deb) in the parent directory. You can install this package using 'dpkg -i' the emc2 and emc2-dev deb files. (the exact filenames depend on the emc2 version number, architecture, and sim vs rtai) If you leave the linuxcnc.org package repositories in your apt configuration, then some future release of emc2 may still appear as an updated version. For example, if you built the v2.4_branch today and installed that deb, then the next bugfix version will be a newer version and will replace your self-built version if you agree to it in the update manager. apt has ways to manage preferred versions of software; search the web to find them. These instructions may work for other debian-based distros, assuming that their naming conventions for the kernel and rtai packages are similar enough to the ones we've adopted on ubuntu. If you use a different distro, then learn how to make an emc2 package in cooperation with your OS's packaging system. For instance, a user has contributed a way to build emc2 for Arch Linux: http://neo-technical.wikispaces.com/emc2-arch I recommend to *NEVER* do a bare 'make install' with emc2. There is NO 'make uninstall' rule and we have no plans to add one--I firmly believe that installing/uninstalling software is a job for the OS's package manager, and that make uninstall is a fundamentally broken idea (and at any rate, it's not needed if the only use of 'make install' is to serve the OS package builder). If you do 'make install' on an Ubuntu system, the installation is different enough from the one you get with a package that any deb you install (or any deb you had already installed) will be subtly or not-so-subtly broken by the files installed by make install. Don't do this; use a package management system instead. (on the other hand, when building the package, there will be a 'make install DESTDIR=...' step that puts all the files in a location that the package manager will use to assemble the binary package) Jeff -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Need help with USC servo mode.
Don Stanley wrote: When the OUTPUT_SCALE is set to +1.0 I was getting 1 step output for each inch of travel. That was actually .04 inches of movement for 1 inch movement shown on the axis display. My drives need 125000 steps per inch of travel (25 steps on the knee). When I set the OUTPUT_SCALE to 125000 move starts became very rough and stalled the motors. I had to change the MAX_ACCELERATION = from 20 to 1 (or less) to get a top speed of 40 inches per minute (as opposed to 60 ipm in non servo mode). Does all this compute with you? UGH! It is embarrassing when I discover I know so little about the products I designed! Well, all I can use to excuse myself is that only a few users actually use the closed-loop stepper mode. So, I don't delve into it often enough to remember how it works. I sort of think I mentioned before that INPUT_SCALE should equal the encoder resolution, and OUTPUT_SCALE should equal the steps per unit resolution, but then I think I contradicted myself. Maybe I need to put definitive comments into the sample files so people know what to do. OK, now you probably have the scale factors right, and you will have to tune the servo response. You need to start up halscope from the machine menu, and then the calibration menu from the same main menu, and adjust the P, D and FF1 and FF2 settings for best response. Watch ppmc.0.encoder.00.delta (gives encoder velocity in raw count units per servo period) and set the scope to trigger off that channel. Then also add a trace for pid.0.error These two traces allow you to see how well it accelerates and follows the desired moves. See http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?PWM_Servo_Amplifiers for some help and sample pictures from this process. The above page was written for my PWM servo system, so some of the response may be just a little different, but the general process and the interpretation of the graphs should be quite similar. Jon -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Stepper Musings
Colin Kingsbury wrote: At first I was not really big on this but the more I think about it, the more I like it. I play with small, benchtop size machines, where inexpensive steppers and drives generally work well and cost half or less of what servos would. A pseudo-servo mechanism that simply tripped a fault when something bad started to happen would provide most if not all of the benefit that true servos would, at much less cost. It's not magic and won't make the machine more precise, but it would make it more fault-tolerant and that seems significant. It would also be a unique competitive edge that could bring a lot of users over to EMC2. Is this something that could be done just by wiring a few ~$50 encoders into a parport, or would you need more specialized IO hardware? Each encoder needs 2 pins, so it could be done with an extra parallel port. But, the software encoder has a speed limit. If you are running a 25 us (SERVO_PERIOD_NS = 25000) then you could keep up with encoders moving at about 40,000 counts/second, but should leave significant margin for noise and timing fluctuations. So, maybe 25,000 counts/sec is a good safety factor. Now, if you have low-res encoders with 200 lines/rev, that gives 800 counts/rev. That is a lot less than a microstepping drive on a stepper, so you really can't use it for closed-loop control, but you can use it for detection of positioning errors. Well, let's take a Sherline or Taig as an example, they have a 20 TPI leadscrew. So, 800 counts/rev * 20 TPI gives 16,000 counts/inch of motion. So, at the 25,000 counts/sec safe limit, this is 1.56 inches/second, or 93 IPM, which is probably excessive for one of those machines. On the other hand, if you wanted to use a 2000 line/rev encoder giving 8000 counts/rev, you would be limited to 9.3 IPM. So, you can do the calculation for the SERVO_PERIOD and the machine/ encoder combination and see if a hardware encoder counter is warranted. Jon -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Stepper Musings
On Mon, Nov 29, 2010 at 3:32 PM, Kirk Wallace kwall...@wallacecompany.com wrote: On Mon, 2010-11-29 at 14:43 -0500, Colin Kingsbury wrote: It's not magic and won't make the machine more precise, but it would make it more fault-tolerant and that seems significant. Maybe not tolerant, but it's nice to get a warning when a step or two are missed and otherwise is not obvious. I think it would be better than a warning---let's say you set an excessive feedrate; the tool will still cut some material on a failed step, so repeating it might finally bring the tool into the desired position. If an encoder provides a reliable feedback, it could result in a machine that misses steps but maintains precise position control. Of course there are situations when repeating the failed step sequence isn't going to improve anything (e.g. resonance). Even then, early indication of a following error lets the machine change the move parameters before the part is ruined. The main difficulty is conceptual: stepper motor systems were always based on number of steps being the control variable. With encoders in the mix, do we keep steps as the main control variable and use encoders as a cross-check and/or a failure detector, or do we switch to encoders as a primary feedback source, or do we switch between them depending on some criteria?? -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Changes to Axis
About changing Axis: The sources sits in /usr/bin/axis and /usr/share/axis/tcl/axis.tcl with images in /usr/share/axis/images. I created a copy called axis_w in /usr/bin and a copy called axis_w.tcl in /usr/share/axis/tcl and modified both these files, also the images in ../images, ie copied tool_run.gif to tool_run_w.gif. Other changes: 1. in .ini file DISPLAY variable now becomes axis_w instead of axis. 2. in axis_w the reference to axis.tcl is changed to axis_w.tcl 3. in axis_w.tcl the reference to images are changed, ie, tool_estop.gif to tool_estop_w.gif, etc. The last changes are only required if you change the images - I scaled them up from 24x24 pixels to 32x32 using GIMP. After a lot of up-sizing of parameters in axis and axis.tcl I now have a AXIS-GUI that is enlarged in all respects and can be used on a touch screen. In this way the original AXIS remains untouched and when you update EMC2 from time to time you do not over-write your own mods. I am not quite finished yet, but it works well on a high res screen. Rudy du Preez -- Increase Visibility of Your 3D Game App Earn a Chance To Win $500! Tap into the largest installed PC base get more eyes on your game by optimizing for Intel(R) Graphics Technology. Get started today with the Intel(R) Software Partner Program. Five $500 cash prizes are up for grabs. http://p.sf.net/sfu/intelisp-dev2dev ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
