Re: [Emc-users] Crackling motors using Beaglebone
I eventually managed to merge a few hal files and ini files to Change the stepgens etc to work in velocity mode. I have just connected up to the machine,and initial testing is excellent. Strange thing though ,i have not entered any deadband figures yet but the crackling seems to have gone. I will let you know how more in depth testing works out, but for now all is good. Can anyone tell me what the maximum figure is that i can set in the beaglebone for stepgen max velocity? At the moment my stepgen max velocity is 42 And the Max velocity is 35 At 1000 steps per mm I seem to remember it max's out at 45khz? On 24/02/14 17:22, Jeff wrote: Hi, I'm *guessing* that they are the older Geckos (non digital). The older drives had to have the DIR line stable for quite a time after the STEP pulse. I believe this was to manage the resonance compensation circuit. This makes me think the DIR line was not actually latched at the time of the STEP pulse. If this is the case, the external DIR line would play an active role in the direction the current is going to be going in the motor windings. Thus, at the start of each PWM cycle (about 20KHz) the DIR line would determine which direction the current should go (even in a stationary motor). As the DIR line changes, the standby current in the motor will be reversed. The rate of DIR reversal coupled with the 20KHz ends up giving a beat frequency in the audible range. Another guess would be that the actual noise signature would be where the drive stopped within the 10 microstep range. You could end up having 10 different crackling noise characteristics depending on which mic rostep you stopped at. While the noise might be annoying, I don't think (another guess) it would cause a problem for the drive as long as the correct DIR polarity is stable before the next STEP pulse comes in. Jeff Date: Sat, 22 Feb 2014 11:30:59 -0800 From: p...@mesanet.com To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone On Sat, 22 Feb 2014, Mark Tucker wrote: Date: Sat, 22 Feb 2014 19:20:57 + From: Mark Tucker m...@rmtucker.f2s.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? The internal stepgen position has a resolution of a small fraction of a step (1/1 of a step in Johns example) so it can hunt back and forth without emitting a step. As to why a step drive pays any attention to the dir signal without a step pulse I do not know, seems like a mistake to me. Peter Wallace Mesa Electronics -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Flow-based real-time traffic analytics software. Cisco certified tool. Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer Customize your own dashboards, set traffic alerts and generate reports. Network behavioral analysis security monitoring. All-in-one tool. http://pubads.g.doubleclick.net/gampad/clk?id=126839071iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Flow-based real-time traffic analytics software. Cisco certified tool. Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer Customize your own dashboards, set traffic alerts and generate reports. Network behavioral analysis security monitoring. All-in-one tool. http://pubads.g.doubleclick.net/gampad/clk?id=126839071iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
The maximum step frequency depends on your PRU task loop time, which depends on how many tasks you're actually running. By default, the PRU task loop is 10 uS, which means step pulses can be generated every 20 uS (one period high, one period low) minimum, which gives a 50 KHz maximum step frequency. You can dial the PRU task period down if you need higher frequencies and are not running lots of tasks. IIRC the default setup I was using for my 3D printer took about 1.5 uS to run the code (4 stepgens and 3 PWMs), so there's a lot of safety margin. On 2/26/2014 11:38 AM, Mark Tucker wrote: I eventually managed to merge a few hal files and ini files to Change the stepgens etc to work in velocity mode. I have just connected up to the machine,and initial testing is excellent. Strange thing though ,i have not entered any deadband figures yet but the crackling seems to have gone. I will let you know how more in depth testing works out, but for now all is good. Can anyone tell me what the maximum figure is that i can set in the beaglebone for stepgen max velocity? At the moment my stepgen max velocity is 42 And the Max velocity is 35 At 1000 steps per mm I seem to remember it max's out at 45khz? On 24/02/14 17:22, Jeff wrote: Hi, I'm *guessing* that they are the older Geckos (non digital). The older drives had to have the DIR line stable for quite a time after the STEP pulse. I believe this was to manage the resonance compensation circuit. This makes me think the DIR line was not actually latched at the time of the STEP pulse. If this is the case, the external DIR line would play an active role in the direction the current is going to be going in the motor windings. Thus, at the start of each PWM cycle (about 20KHz) the DIR line would determine which direction the current should go (even in a stationary motor). As the DIR line changes, the standby current in the motor will be reversed. The rate of DIR reversal coupled with the 20KHz ends up giving a beat frequency in the audible range. Another guess would be that the actual noise signature would be where the drive stopped within the 10 microstep range. You could end up having 10 different crackling noise characteristics depending on which m icrostep you stopped at. While the noise might be annoying, I don't think (another guess) it would cause a problem for the drive as long as the correct DIR polarity is stable before the next STEP pulse comes in. Jeff Date: Sat, 22 Feb 2014 11:30:59 -0800 From: p...@mesanet.com To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone On Sat, 22 Feb 2014, Mark Tucker wrote: Date: Sat, 22 Feb 2014 19:20:57 + From: Mark Tucker m...@rmtucker.f2s.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? The internal stepgen position has a resolution of a small fraction of a step (1/1 of a step in Johns example) so it can hunt back and forth without emitting a step. As to why a step drive pays any attention to the dir signal without a step pulse I do not know, seems like a mistake to me. Peter Wallace Mesa Electronics -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Flow-based real-time traffic analytics software. Cisco certified tool. Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer Customize your own dashboards, set traffic alerts and generate reports. Network behavioral analysis security monitoring. All-in-one tool. http://pubads.g.doubleclick.net/gampad/clk?id=126839071iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Hi, I'm *guessing* that they are the older Geckos (non digital). The older drives had to have the DIR line stable for quite a time after the STEP pulse. I believe this was to manage the resonance compensation circuit. This makes me think the DIR line was not actually latched at the time of the STEP pulse. If this is the case, the external DIR line would play an active role in the direction the current is going to be going in the motor windings. Thus, at the start of each PWM cycle (about 20KHz) the DIR line would determine which direction the current should go (even in a stationary motor). As the DIR line changes, the standby current in the motor will be reversed. The rate of DIR reversal coupled with the 20KHz ends up giving a beat frequency in the audible range. Another guess would be that the actual noise signature would be where the drive stopped within the 10 microstep range. You could end up having 10 different crackling noise characteristics depending on which microstep you stopped at. While the noise might be annoying, I don't think (another guess) it would cause a problem for the drive as long as the correct DIR polarity is stable before the next STEP pulse comes in. Jeff Date: Sat, 22 Feb 2014 11:30:59 -0800 From: p...@mesanet.com To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone On Sat, 22 Feb 2014, Mark Tucker wrote: Date: Sat, 22 Feb 2014 19:20:57 + From: Mark Tucker m...@rmtucker.f2s.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? The internal stepgen position has a resolution of a small fraction of a step (1/1 of a step in Johns example) so it can hunt back and forth without emitting a step. As to why a step drive pays any attention to the dir signal without a step pulse I do not know, seems like a mistake to me. Peter Wallace Mesa Electronics -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Flow-based real-time traffic analytics software. Cisco certified tool. Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer Customize your own dashboards, set traffic alerts and generate reports. Network behavioral analysis security monitoring. All-in-one tool. http://pubads.g.doubleclick.net/gampad/clk?id=126839071iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
You might try hanging a current probe on the output of the Gecko to see if it is switching between run current mode and standby current mode when the direction line is being toggled. It shouldn't cause any harm, just more power used. Ray --J. Ray Mitchell Jr. jrmitche...@gmail.com (818)324-7573 Normal people ... believe that if it ain't broke, don't fix it. Engineers believe that if it ain't broke, it doesn't have enough features yet. -- Scott Adams, creator of Dilbert comic strip On Sat, Feb 22, 2014 at 12:20 PM, Dave Cole linuxcncro...@gmail.com wrote: Damage the Gecko?? That is extremely unlikely. If it is not going into standby your motor might get hot, but if you have the Gecko properly heatsinked there should not be an issue with it. Dave On 2/22/2014 2:57 PM, Mark Tucker wrote: Thanks That seems to have nailed it for me now i can very clearly understand why no pulse is emitted on the pulse line. Well that brings us back to the question of who is going to fix the problem? Is there anyone else working on this other than charles that can maybe work around this using the stepgen velocity mode and deadband etc in Hal? I am a little worried about using it on a daily basis just in case it is damaging the Gecko. I will maybe see if i can get an explanation on one of the Geckodrive haunts. On 22/02/14 19:30, Peter C. Wallace wrote: On Sat, 22 Feb 2014, Mark Tucker wrote: Date: Sat, 22 Feb 2014 19:20:57 + From: Mark Tucker m...@rmtucker.f2s.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? The internal stepgen position has a resolution of a small fraction of a step (1/1 of a step in Johns example) so it can hunt back and forth without emitting a step. As to why a step drive pays any attention to the dir signal without a step pulse I do not know, seems like a mistake to me. Peter Wallace Mesa Electronics -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Ray As far as i know i have Standby Disabled on the gecko,but i will check On 23/02/14 15:07, jrmitchellj . wrote: You might try hanging a current probe on the output of the Gecko to see if it is switching between run current mode and standby current mode when the direction line is being toggled. It shouldn't cause any harm, just more power used. Ray --J. Ray Mitchell Jr. jrmitche...@gmail.com (818)324-7573 Normal people ... believe that if it ain't broke, don't fix it. Engineers believe that if it ain't broke, it doesn't have enough features yet. -- Scott Adams, creator of Dilbert comic strip On Sat, Feb 22, 2014 at 12:20 PM, Dave Cole linuxcncro...@gmail.com wrote: Damage the Gecko?? That is extremely unlikely. If it is not going into standby your motor might get hot, but if you have the Gecko properly heatsinked there should not be an issue with it. Dave On 2/22/2014 2:57 PM, Mark Tucker wrote: Thanks That seems to have nailed it for me now i can very clearly understand why no pulse is emitted on the pulse line. Well that brings us back to the question of who is going to fix the problem? Is there anyone else working on this other than charles that can maybe work around this using the stepgen velocity mode and deadband etc in Hal? I am a little worried about using it on a daily basis just in case it is damaging the Gecko. I will maybe see if i can get an explanation on one of the Geckodrive haunts. On 22/02/14 19:30, Peter C. Wallace wrote: On Sat, 22 Feb 2014, Mark Tucker wrote: Date: Sat, 22 Feb 2014 19:20:57 + From: Mark Tucker m...@rmtucker.f2s.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? The internal stepgen position has a resolution of a small fraction of a step (1/1 of a step in Johns example) so it can hunt back and forth without emitting a step. As to why a step drive pays any attention to the dir signal without a step pulse I do not know, seems like a mistake to me. Peter Wallace Mesa Electronics -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Peter The crackling is random and mainly after jog moves. The motors are Nema34 and running at 72v and approc 4amps. On 21/02/14 22:25, peter smith wrote: Mark What type of motors and voltage are you using, is the crackling random, or specifically after a certain type of move?? Regards Peter Smith On 21/02/14 16:55, Jon Elson wrote: On 02/21/2014 05:41 AM, Mark Tucker wrote: So it seems that the hal configuration has to be altered and the ini,just reading the sample pico configs. All i need now is someone to integrate this into the beaglebone/xylotex db25 configs. How is the deadband figure worked out,Trial and error? I should have said it in my first message, slightly more than 1/2 the step resolution suppresses the need to move if off by less than a single step. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
You can hear it on this video http://www.youtube.com/watch?v=aMA6B4n1bGA On 22/02/14 09:52, Mark Tucker wrote: Peter The crackling is random and mainly after jog moves. The motors are Nema34 and running at 72v and approc 4amps. On 21/02/14 22:25, peter smith wrote: Mark What type of motors and voltage are you using, is the crackling random, or specifically after a certain type of move?? Regards Peter Smith On 21/02/14 16:55, Jon Elson wrote: On 02/21/2014 05:41 AM, Mark Tucker wrote: So it seems that the hal configuration has to be altered and the ini,just reading the sample pico configs. All i need now is someone to integrate this into the beaglebone/xylotex db25 configs. How is the deadband figure worked out,Trial and error? I should have said it in my first message, slightly more than 1/2 the step resolution suppresses the need to move if off by less than a single step. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Note to those checking out the video. You will need to have the volume turned up high. The cracking occurs during most of the video and it sounds like an old fashioned Geiger counter ticking to me. Steve Stallings -Original Message- From: Mark Tucker [mailto:m...@rmtucker.f2s.com] Sent: Saturday, February 22, 2014 4:52 AM To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone Peter The crackling is random and mainly after jog moves. The motors are Nema34 and running at 72v and approc 4amps. On 21/02/14 22:25, peter smith wrote: Mark What type of motors and voltage are you using, is the crackling random, or specifically after a certain type of move?? Regards Peter Smith On 21/02/14 16:55, Jon Elson wrote: On 02/21/2014 05:41 AM, Mark Tucker wrote: So it seems that the hal configuration has to be altered and the ini,just reading the sample pico configs. All i need now is someone to integrate this into the beaglebone/xylotex db25 configs. How is the deadband figure worked out,Trial and error? I should have said it in my first message, slightly more than 1/2 the step resolution suppresses the need to move if off by less than a single step. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/41 40/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/41 40/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/41 40/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
I seem to remember there being a fix for this around v2.3 or something to stop the stepper motors hunting.which i assume must have been a parameter to set the tolerance for acceptable position. Does this not apply when using hardware generated pulses? I will have to leave the beaglebone on the bench until charles has time to sort this one out. I don't think it is doing any damage but it really does sound awful. On 22/02/14 15:08, Steve Stallings wrote: Note to those checking out the video. You will need to have the volume turned up high. The cracking occurs during most of the video and it sounds like an old fashioned Geiger counter ticking to me. Steve Stallings -Original Message- From: Mark Tucker [mailto:m...@rmtucker.f2s.com] Sent: Saturday, February 22, 2014 4:52 AM To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone Peter The crackling is random and mainly after jog moves. The motors are Nema34 and running at 72v and approc 4amps. On 21/02/14 22:25, peter smith wrote: Mark What type of motors and voltage are you using, is the crackling random, or specifically after a certain type of move?? Regards Peter Smith On 21/02/14 16:55, Jon Elson wrote: On 02/21/2014 05:41 AM, Mark Tucker wrote: So it seems that the hal configuration has to be altered and the ini,just reading the sample pico configs. All i need now is someone to integrate this into the beaglebone/xylotex db25 configs. How is the deadband figure worked out,Trial and error? I should have said it in my first message, slightly more than 1/2 the step resolution suppresses the need to move if off by less than a single step. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/41 40/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/41 40/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/41 40/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Are steps also being generated (back and forth) or is just the direction line toggling (w/ no steps)? On Sat, Feb 22, 2014 at 10:56 AM, Mark Tucker m...@rmtucker.f2s.com wrote: I seem to remember there being a fix for this around v2.3 or something to stop the stepper motors hunting.which i assume must have been a parameter to set the tolerance for acceptable position. Does this not apply when using hardware generated pulses? I will have to leave the beaglebone on the bench until charles has time to sort this one out. I don't think it is doing any damage but it really does sound awful. On 22/02/14 15:08, Steve Stallings wrote: Note to those checking out the video. You will need to have the volume turned up high. The cracking occurs during most of the video and it sounds like an old fashioned Geiger counter ticking to me. Steve Stallings -Original Message- From: Mark Tucker [mailto:m...@rmtucker.f2s.com] Sent: Saturday, February 22, 2014 4:52 AM To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone Peter The crackling is random and mainly after jog moves. The motors are Nema34 and running at 72v and approc 4amps. On 21/02/14 22:25, peter smith wrote: Mark What type of motors and voltage are you using, is the crackling random, or specifically after a certain type of move?? Regards Peter Smith On 21/02/14 16:55, Jon Elson wrote: On 02/21/2014 05:41 AM, Mark Tucker wrote: So it seems that the hal configuration has to be altered and the ini,just reading the sample pico configs. All i need now is someone to integrate this into the beaglebone/xylotex db25 configs. How is the deadband figure worked out,Trial and error? I should have said it in my first message, slightly more than 1/2 the step resolution suppresses the need to move if off by less than a single step. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/41 40/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/41 40/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/41 40/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Jumping in - I have had this with the MachineKit. No noise but as I had the 'scope on the signals I spotted the fidgeting Dir. I had no pulses on Step line, just Dir hunting. I was worried that it might stop the stepper drivers going to reduced current mode but with the ones I was using this was OK. Best wishes John Prentice -Original Message- From: Stephen Dubovsky [mailto:smdubov...@gmail.com] Sent: 22 February 2014 16:33 To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] Crackling motors using Beaglebone Are steps also being generated (back and forth) or is just the direction line toggling (w/ no steps)? On Sat, Feb 22, 2014 at 10:56 AM, Mark Tucker m...@rmtucker.f2s.com wrote: I seem to remember there being a fix for this around v2.3 or something to stop the stepper motors hunting.which i assume must have been a parameter to set the tolerance for acceptable position. Does this not apply when using hardware generated pulses? I will have to leave the beaglebone on the bench until charles has time to sort this one out. I don't think it is doing any damage but it really does sound awful. -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
John I don't suppose you are using Gecko's? As Jeff mentioned earlier it seems like a Gecko driver does not like the Dir line wiggled about in that fashion. Why it should make a noise beats me,but i can assure everyone that the drives are running without these noises on a pc setup and have been for many years. Also if the machine comes to a halt and the motor hunts because it is not in the exact position ie 1/2 step out,The step line would also be stepping to adjust the position. Or am i not grasping this? On 22/02/14 17:11, John Prentice (FS) wrote: Jumping in - I have had this with the MachineKit. No noise but as I had the 'scope on the signals I spotted the fidgeting Dir. I had no pulses on Step line, just Dir hunting. I was worried that it might stop the stepper drivers going to reduced current mode but with the ones I was using this was OK. Best wishes John Prentice -Original Message- From: Stephen Dubovsky [mailto:smdubov...@gmail.com] Sent: 22 February 2014 16:33 To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] Crackling motors using Beaglebone Are steps also being generated (back and forth) or is just the direction line toggling (w/ no steps)? On Sat, Feb 22, 2014 at 10:56 AM, Mark Tucker m...@rmtucker.f2s.com wrote: I seem to remember there being a fix for this around v2.3 or something to stop the stepper motors hunting.which i assume must have been a parameter to set the tolerance for acceptable position. Does this not apply when using hardware generated pulses? I will have to leave the beaglebone on the bench until charles has time to sort this one out. I don't think it is doing any damage but it really does sound awful. -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Some background on the hunting behavior of the dir line. It goes back to the implementation of the step generator. This applies specifically to the software step generator, but some of the FPGA based ones and perhaps the BBB PRU one use the same core algorithm and have the same behavior. Everything in the base thread of the step generator is based on integers. The way that the step generator works is that it has a fairly wide (32 to 48 bits) position accumulator. For example purposes, I'm going to pretend that it is a 9 digit wide decimal number - it can run from 0 to 999,999,999, then it rolls over back to zero. Every base period, the code adds a number to this position accumulator. The number is directly proportional to the desired step frequency. For my example, I'm going to pretend that the base period is 100uS, which means the addition happens 10,000 times per second. If I want a frequency of 1 step per second, I can add 1 every time. Since I'm adding 10,000 times per second, the accumulator will increase by 10,000 every second. But I only want one step per second. So the code generates a step only when the 5th digit of the accumulator changes. So when the accumulator rolls over from 9,999 to 10,000, it makes a step. It makes another step when it rolls from 19,999 to 20,000, and when it goes from 29,999 to 30,000. If the axis is moving the other way, it adds -1 every time, and generates a reverse step when it rolls from 30,000 down to 29,999, etc. If I want to generate 3827 steps per second, I simply add 3827 to the accumulator every 1/1th of a second. It will count something like: 0 3827 7654 11481 -- fifth digit changed, make a step 15208 19125 22962 -- fifth digit changed, make a step 26789 30616 -- fifth digit changed, make a step In that example, you can see that sometimes it steps after three base periods (300uS) and sometimes after only two (200uS). The desired period is actually 261.3uS (1/3827), but this algorithm will jump back and forth between 200uS and 300uS such that the average is exactly what we want. Basically, the position accumulator is split into two parts. The lower digits count fractions of a step (1/10,000s of a step in my example), and the higher digits count whole steps. The entire accumulator is used to close the position loop, so you can command a position that is between steps and the loop can still be satisfied. But depending on tuning, it might be hunting back and forth by a very small fraction of a step - maybe 1/100th of a step. As the position loop fiddles with the velocity to try to get to the exact position (down to 1/1th of a step), it will hunt back and forth, changing the velocity from a small negative value to positive and back. In some versions of the step generator, the direction bit comes straight from the sign of the velocity command, so it will change too. I think that the software step generator was tweaked a long time ago so that it doesn't change the direction bit unless it actually needs to because it is about to roll over and generate a real step. But it's been a long time and I'm not sure. I also have no idea if the FPGA based step generators (or the BBB PRU step generator) can do the same thing. John Kasunich (I wrote the original HAL software step generator) On Sat, Feb 22, 2014, at 01:08 PM, Mark Tucker wrote: John I don't suppose you are using Gecko's? As Jeff mentioned earlier it seems like a Gecko driver does not like the Dir line wiggled about in that fashion. Why it should make a noise beats me,but i can assure everyone that the drives are running without these noises on a pc setup and have been for many years. Also if the machine comes to a halt and the motor hunts because it is not in the exact position ie 1/2 step out,The step line would also be stepping to adjust the position. Or am i not grasping this? On 22/02/14 17:11, John Prentice (FS) wrote: Jumping in - I have had this with the MachineKit. No noise but as I had the 'scope on the signals I spotted the fidgeting Dir. I had no pulses on Step line, just Dir hunting. I was worried that it might stop the stepper drivers going to reduced current mode but with the ones I was using this was OK. Best wishes John Prentice -Original Message- From: Stephen Dubovsky [mailto:smdubov...@gmail.com] Sent: 22 February 2014 16:33 To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] Crackling motors using Beaglebone Are steps also being generated (back and forth) or is just the direction line toggling (w/ no steps)? On Sat, Feb 22, 2014 at 10:56 AM, Mark Tucker m...@rmtucker.f2s.com wrote: I seem to remember there being a fix for this around v2.3 or something to stop the stepper motors hunting.which i assume must have been a parameter to set the tolerance for acceptable position. Does this not apply when using hardware generated pulses? I will have to leave the beaglebone
Re: [Emc-users] Crackling motors using Beaglebone
Mark Not Geckos here but a Leadshine 3 phase stepper motor driver. I think John K has covered more bases than I ever could. In essence I see it as the accumulator counting up and down but not overflowing so a step never gets emitted but the sign of the error is changing so Dir follows this. Best wishes John Prentice -Original Message- From: Mark Tucker [mailto:m...@rmtucker.f2s.com] Sent: 22 February 2014 18:08 To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] Crackling motors using Beaglebone John I don't suppose you are using Gecko's? As Jeff mentioned earlier it seems like a Gecko driver does not like the Dir line wiggled about in that fashion. Why it should make a noise beats me,but i can assure everyone that the drives are running without these noises on a pc setup and have been for many years. Also if the machine comes to a halt and the motor hunts because it is not in the exact position ie 1/2 step out,The step line would also be stepping to adjust the position. Or am i not grasping this? -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? On 22/02/14 19:05, John Kasunich wrote: Some background on the hunting behavior of the dir line. It goes back to the implementation of the step generator. This applies specifically to the software step generator, but some of the FPGA based ones and perhaps the BBB PRU one use the same core algorithm and have the same behavior. Everything in the base thread of the step generator is based on integers. The way that the step generator works is that it has a fairly wide (32 to 48 bits) position accumulator. For example purposes, I'm going to pretend that it is a 9 digit wide decimal number - it can run from 0 to 999,999,999, then it rolls over back to zero. Every base period, the code adds a number to this position accumulator. The number is directly proportional to the desired step frequency. For my example, I'm going to pretend that the base period is 100uS, which means the addition happens 10,000 times per second. If I want a frequency of 1 step per second, I can add 1 every time. Since I'm adding 10,000 times per second, the accumulator will increase by 10,000 every second. But I only want one step per second. So the code generates a step only when the 5th digit of the accumulator changes. So when the accumulator rolls over from 9,999 to 10,000, it makes a step. It makes another step when it rolls from 19,999 to 20,000, and when it goes from 29,999 to 30,000. If the axis is moving the other way, it adds -1 every time, and generates a reverse step when it rolls from 30,000 down to 29,999, etc. If I want to generate 3827 steps per second, I simply add 3827 to the accumulator every 1/1th of a second. It will count something like: 0 3827 7654 11481 -- fifth digit changed, make a step 15208 19125 22962 -- fifth digit changed, make a step 26789 30616 -- fifth digit changed, make a step In that example, you can see that sometimes it steps after three base periods (300uS) and sometimes after only two (200uS). The desired period is actually 261.3uS (1/3827), but this algorithm will jump back and forth between 200uS and 300uS such that the average is exactly what we want. Basically, the position accumulator is split into two parts. The lower digits count fractions of a step (1/10,000s of a step in my example), and the higher digits count whole steps. The entire accumulator is used to close the position loop, so you can command a position that is between steps and the loop can still be satisfied. But depending on tuning, it might be hunting back and forth by a very small fraction of a step - maybe 1/100th of a step. As the position loop fiddles with the velocity to try to get to the exact position (down to 1/1th of a step), it will hunt back and forth, changing the velocity from a small negative value to positive and back. In some versions of the step generator, the direction bit comes straight from the sign of the velocity command, so it will change too. I think that the software step generator was tweaked a long time ago so that it doesn't change the direction bit unless it actually needs to because it is about to roll over and generate a real step. But it's been a long time and I'm not sure. I also have no idea if the FPGA based step generators (or the BBB PRU step generator) can do the same thing. John Kasunich (I wrote the original HAL software step generator) On Sat, Feb 22, 2014, at 01:08 PM, Mark Tucker wrote: John I don't suppose you are using Gecko's? As Jeff mentioned earlier it seems like a Gecko driver does not like the Dir line wiggled about in that fashion. Why it should make a noise beats me,but i can assure everyone that the drives are running without these noises on a pc setup and have been for many years. Also if the machine comes to a halt and the motor hunts because it is not in the exact position ie 1/2 step out,The step line would also be stepping to adjust the position. Or am i not grasping this? On 22/02/14 17:11, John Prentice (FS) wrote: Jumping in - I have had this with the MachineKit. No noise but as I had the 'scope on the signals I spotted the fidgeting Dir. I had no pulses on Step line, just Dir hunting. I was worried that it might stop the stepper drivers going to reduced current mode but with the ones I was using this was OK. Best wishes John Prentice -Original Message- From: Stephen Dubovsky [mailto:smdubov...@gmail.com] Sent: 22 February 2014 16:33 To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] Crackling motors using
Re: [Emc-users] Crackling motors using Beaglebone
On Sat, 22 Feb 2014, Mark Tucker wrote: Date: Sat, 22 Feb 2014 19:20:57 + From: Mark Tucker m...@rmtucker.f2s.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? The internal stepgen position has a resolution of a small fraction of a step (1/1 of a step in Johns example) so it can hunt back and forth without emitting a step. As to why a step drive pays any attention to the dir signal without a step pulse I do not know, seems like a mistake to me. Peter Wallace Mesa Electronics -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
On Sat, Feb 22, 2014, at 02:20 PM, Mark Tucker wrote: John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? Lets take my example of a 100uS base thread and an accumulator that makes a step every time the 5th digit changes. Suppose the position command is 324,556, and you start out somewhere below that, say 300,000. The velocity is positive, and a positive number is added to the accumulator 1 times a second. At some point, the accumulator passes 320,000, and the final step of the move is sent to the drive. There is still a small position error (4556 counts, or 0.4556 steps). The position loop will keep commanding a non-zero velocity until the accumulator reaches 324,556. It might overshoot a bit - maybe to 325,920. Then it starts going back down. It hunts around and hopefully settles down at 324,556. Maybe it never fully settles, but is bouncing around from 324,550 to 324,561 or so. But in any case, it never reaches 330,000, so it never sends another forward step. And it never gets as low as 320,000, so it doesn't send a reverse step. And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? That is a very good question, and depends on the design of the drive. -- John Kasunich jmkasun...@fastmail.fm -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Thanks That seems to have nailed it for me now i can very clearly understand why no pulse is emitted on the pulse line. Well that brings us back to the question of who is going to fix the problem? Is there anyone else working on this other than charles that can maybe work around this using the stepgen velocity mode and deadband etc in Hal? I am a little worried about using it on a daily basis just in case it is damaging the Gecko. I will maybe see if i can get an explanation on one of the Geckodrive haunts. On 22/02/14 19:30, Peter C. Wallace wrote: On Sat, 22 Feb 2014, Mark Tucker wrote: Date: Sat, 22 Feb 2014 19:20:57 + From: Mark Tucker m...@rmtucker.f2s.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? The internal stepgen position has a resolution of a small fraction of a step (1/1 of a step in Johns example) so it can hunt back and forth without emitting a step. As to why a step drive pays any attention to the dir signal without a step pulse I do not know, seems like a mistake to me. Peter Wallace Mesa Electronics -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
On Saturday 22 February 2014 14:59:52 John Kasunich did opine: On Sat, Feb 22, 2014, at 02:20 PM, Mark Tucker wrote: John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? Lets take my example of a 100uS base thread and an accumulator that makes a step every time the 5th digit changes. Suppose the position command is 324,556, and you start out somewhere below that, say 300,000. The velocity is positive, and a positive number is added to the accumulator 1 times a second. At some point, the accumulator passes 320,000, and the final step of the move is sent to the drive. There is still a small position error (4556 counts, or 0.4556 steps). The position loop will keep commanding a non-zero velocity until the accumulator reaches 324,556. It might overshoot a bit - maybe to 325,920. Then it starts going back down. It hunts around and hopefully settles down at 324,556. Maybe it never fully settles, but is bouncing around from 324,550 to 324,561 or so. But in any case, it never reaches 330,000, so it never sends another forward step. And it never gets as low as 320,000, so it doesn't send a reverse step. And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? That is a very good question, and depends on the design of the drive. I am with Peter on this, until a step is received by the driver, the state of the dir pin shouldn't mean squat, however if the fluttering sign is being propagated on to the output of the dir pin, it seems to me that the problem could be solved by not toggling the dir line until the NEXT loop WILL issue the step. The step timing should not be held back as that would confuse the TP, but it seems like we could detect the need for a step one pass through the thread hence, and use that to toggle the dir line. Maybe a hal calculated guard band value dependent of the instant speed might be needed to handle the transition from stopped to moving? How much more complex would that actually make the stepgen? Cheers, Gene -- 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 NOTICE: Will pay 100 USD for an HP-4815A defective but complete probe assembly. -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
On Sat, 22 Feb 2014, Mark Tucker wrote: Date: Sat, 22 Feb 2014 19:57:26 + From: Mark Tucker m...@rmtucker.f2s.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone Thanks That seems to have nailed it for me now i can very clearly understand why no pulse is emitted on the pulse line. Well that brings us back to the question of who is going to fix the problem? Is there anyone else working on this other than charles that can maybe work around this using the stepgen velocity mode and deadband etc in Hal? I am a little worried about using it on a daily basis just in case it is damaging the Gecko. I will maybe see if i can get an explanation on one of the Geckodrive haunts. I think for hardware stepgens (that have much better short term timing than the servo thread) using the stepgens in velocity mode and a PID loop like a normal servo is a better solution because PID tuning allows tuning around these problems: dithering when stopped, excessive velocity corrections caused by servo thread jitter, servothread/hardware timebase differences. Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Damage the Gecko?? That is extremely unlikely. If it is not going into standby your motor might get hot, but if you have the Gecko properly heatsinked there should not be an issue with it. Dave On 2/22/2014 2:57 PM, Mark Tucker wrote: Thanks That seems to have nailed it for me now i can very clearly understand why no pulse is emitted on the pulse line. Well that brings us back to the question of who is going to fix the problem? Is there anyone else working on this other than charles that can maybe work around this using the stepgen velocity mode and deadband etc in Hal? I am a little worried about using it on a daily basis just in case it is damaging the Gecko. I will maybe see if i can get an explanation on one of the Geckodrive haunts. On 22/02/14 19:30, Peter C. Wallace wrote: On Sat, 22 Feb 2014, Mark Tucker wrote: Date: Sat, 22 Feb 2014 19:20:57 + From: Mark Tucker m...@rmtucker.f2s.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone John Thank you so much for the insight of how that work and it explains a lot. But as you stated it would be hunting back and forth.Which i assume it would have to pulse the step line? And a number of people have scoped the outputs and only found the Dir line hunting back and forth,i wonder why it is not detected on the step line.? And if it is only the dir line,why would the motors make a noise at all? The internal stepgen position has a resolution of a small fraction of a step (1/1 of a step in Johns example) so it can hunt back and forth without emitting a step. As to why a step drive pays any attention to the dir signal without a step pulse I do not know, seems like a mistake to me. Peter Wallace Mesa Electronics -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
So it seems that the hal configuration has to be altered and the ini,just reading the sample pico configs. All i need now is someone to integrate this into the beaglebone/xylotex db25 configs. How is the deadband figure worked out,Trial and error? On 21/02/14 05:47, Jon Elson wrote: On 02/20/2014 12:01 PM, Charles Steinkuehler wrote: Peter's solution will work. I was going to add a dead-band to the PID control internal to the HAL component that talks to the PRU, but Peter's suggestion of pushing the PID outside the PRU driver and into HAL makes a lot more sense. I might mention that I have to use deadband with the Pico universal stepper controller, as it uses the traditional PID and the step generator is velocity only. This allows the board to be used with either open- or closed-loop stepper setups with minimal change. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
On 02/20/2014 11:47 PM, Jon Elson wrote: On 02/20/2014 12:01 PM, Charles Steinkuehler wrote: Peter's solution will work. I was going to add a dead-band to the PID control internal to the HAL component that talks to the PRU, but Peter's suggestion of pushing the PID outside the PRU driver and into HAL makes a lot more sense. I might mention that I have to use deadband with the Pico universal stepper controller, as it uses the traditional PID and the step generator is velocity only. This allows the board to be used with either open- or closed-loop stepper setups with minimal change. I meant to add, the reason is that otherwise there are positions that can be commanded in the G-code that are between discrete step positions, and the PID will endlessly hunt back and forth between the surrounding step positions if you don't give it a deadband. So, a deadband of slightly more than the step resolution seems to solve it. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
On 02/21/2014 05:41 AM, Mark Tucker wrote: So it seems that the hal configuration has to be altered and the ini,just reading the sample pico configs. All i need now is someone to integrate this into the beaglebone/xylotex db25 configs. How is the deadband figure worked out,Trial and error? I should have said it in my first message, slightly more than 1/2 the step resolution suppresses the need to move if off by less than a single step. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Mark What type of motors and voltage are you using, is the crackling random, or specifically after a certain type of move?? Regards Peter Smith On 21/02/14 16:55, Jon Elson wrote: On 02/21/2014 05:41 AM, Mark Tucker wrote: So it seems that the hal configuration has to be altered and the ini,just reading the sample pico configs. All i need now is someone to integrate this into the beaglebone/xylotex db25 configs. How is the deadband figure worked out,Trial and error? I should have said it in my first message, slightly more than 1/2 the step resolution suppresses the need to move if off by less than a single step. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Mark What type of motors and voltage are you using, is the crackling random, or specifically after a certain type of move?? Regards Peter Smith On 21/02/14 16:55, Jon Elson wrote: On 02/21/2014 05:41 AM, Mark Tucker wrote: So it seems that the hal configuration has to be altered and the ini,just reading the sample pico configs. All i need now is someone to integrate this into the beaglebone/xylotex db25 configs. How is the deadband figure worked out,Trial and error? I should have said it in my first message, slightly more than 1/2 the step resolution suppresses the need to move if off by less than a single step. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
On 2/20/2014 10:21 AM, Mark Tucker wrote: Ok i am not well enough conversed to explain this in detail,but i will try. Having recently been involved with the beaglebone/machinekit setup,i accidently came across a problem. I found that speradically the motors would make a noise like frying an egg after movement had finished. This after some investigation by Charles,Jeff pollard,and few others,was found to be the dir line hunting after a movement. This has turned out to be a known problem with the pru and the fact it is using position feedback and not velocity feedback. So the outcome after a few discussions was that the hal file needs changing to utilise the stepgen in velocity mode. Now i am at a complete loss how to do this,so is there anyone out there that can help? Charles is snowed under at the moment otherwise i am sure he would oblige. I will try attatching my hal file. I am sure there are others that will explain this better than me because of my limited knowledge. Peter Wallace provided the following excellent advice, which I forwarded to Mark. I'm a bit too busy to fiddle with the HAL code for a week or so, and was hoping someone might be able to help Mark get his HAL file sorted out: Quote from Peter: The current position mode driver code makes sense for a software implementation but suffers from some issues when used with a hardware stepgen (and since the PRU stepgen is a asynchronous (to servo thread) DDS it probably has the same issues) To do this you set the stepgen in velocity mode, and set a P of around 50 and a FF1 of 1.000. The nice thing about this is you can now use the PID comps facilites to fix a number of deficiencies in the built in position mode code: 1. Setting the PID comps maxerror to some small value makes the stepgen avoid large corrections based on the servo thread jitter in sampling the stepgens position (effectively slew limiting the corrections) this make sense for hardware or PRU based system where the stepgen DDS is a better timing reference to short term timing than the servo thread. 2. Setting the PID comps dead zone stops the toggling 3. A tiny bit of FF2 can be used to compensate for the delay between sampling the stepgen position and writing the new DDS rate In my testing, if you have any significant servo thread jitter, using a servo type config like this results in much better stepgen performance the the built in position mode controller freeby.mesanet.com/7i76e.zip has an example servo mode stepgen setup -- Charles Steinkuehler char...@steinkuehler.net signature.asc Description: OpenPGP digital signature -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Mark, when this happens, have you tried unplugging the step and dir(everything but enable) from the beaglebone to verify that it isn't just coming from microstepping on the driver itself? I know I've experienced similar crackling sounds on some stepper drivers that was completely isolated from input from step/dir source. On Thu, Feb 20, 2014 at 10:21 AM, Mark Tucker m...@rmtucker.f2s.com wrote: Ok i am not well enough conversed to explain this in detail,but i will try. Having recently been involved with the beaglebone/machinekit setup,i accidently came across a problem. I found that speradically the motors would make a noise like frying an egg after movement had finished. This after some investigation by Charles,Jeff pollard,and few others,was found to be the dir line hunting after a movement. This has turned out to be a known problem with the pru and the fact it is using position feedback and not velocity feedback. So the outcome after a few discussions was that the hal file needs changing to utilise the stepgen in velocity mode. Now i am at a complete loss how to do this,so is there anyone out there that can help? Charles is snowed under at the moment otherwise i am sure he would oblige. I will try attatching my hal file. I am sure there are others that will explain this better than me because of my limited knowledge. -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Josiah Morgan, P.E. -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
The drivers have been working on mach3 for the last 5years with no problem,and also work no problem with linuxcnc on a pc. I believe jeff pollard has scoped the output on the dir line and it is clearly visible. On 20/02/14 16:43, Josiah Morgan wrote: Mark, when this happens, have you tried unplugging the step and dir(everything but enable) from the beaglebone to verify that it isn't just coming from microstepping on the driver itself? I know I've experienced similar crackling sounds on some stepper drivers that was completely isolated from input from step/dir source. On Thu, Feb 20, 2014 at 10:21 AM, Mark Tucker m...@rmtucker.f2s.com wrote: Ok i am not well enough conversed to explain this in detail,but i will try. Having recently been involved with the beaglebone/machinekit setup,i accidently came across a problem. I found that speradically the motors would make a noise like frying an egg after movement had finished. This after some investigation by Charles,Jeff pollard,and few others,was found to be the dir line hunting after a movement. This has turned out to be a known problem with the pru and the fact it is using position feedback and not velocity feedback. So the outcome after a few discussions was that the hal file needs changing to utilise the stepgen in velocity mode. Now i am at a complete loss how to do this,so is there anyone out there that can help? Charles is snowed under at the moment otherwise i am sure he would oblige. I will try attatching my hal file. I am sure there are others that will explain this better than me because of my limited knowledge. -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Hi, I looked at the DIR line on a bare beagle bone with no attachments. The DIR line can end up toggling after a move has stopped. But it does not *always* end up toggling after a move. Pressing the power button in AXIS clears the situation until a future move. The STEP line does remain inactive, so there is no unwanted movement. Mark is using Geckos which are optically isolated, so the chance of electrical noise contributing to the problem is unlikely. I've also noticed the problem with the Allegro A3977 drive chips. I'm not sure why either the Geckos or the A3977 would care about a toggling DIR line while STEP is inactive, but they do. Perhaps it is some kind of noise issue within the drive itself (i.e. not electrical in the wiring/grounding sense). In any case, the solution (when found) will be to stop the line from toggling at all. Hopefully Peter's suggestion of a different HAL configuration will work. Jeff Date: Thu, 20 Feb 2014 16:53:07 + From: m...@rmtucker.f2s.com To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone The drivers have been working on mach3 for the last 5years with no problem,and also work no problem with linuxcnc on a pc. I believe jeff pollard has scoped the output on the dir line and it is clearly visible. On 20/02/14 16:43, Josiah Morgan wrote: Mark, when this happens, have you tried unplugging the step and dir(everything but enable) from the beaglebone to verify that it isn't just coming from microstepping on the driver itself? I know I've experienced similar crackling sounds on some stepper drivers that was completely isolated from input from step/dir source. On Thu, Feb 20, 2014 at 10:21 AM, Mark Tucker m...@rmtucker.f2s.com wrote: Ok i am not well enough conversed to explain this in detail,but i will try. Having recently been involved with the beaglebone/machinekit setup,i accidently came across a problem. I found that speradically the motors would make a noise like frying an egg after movement had finished. This after some investigation by Charles,Jeff pollard,and few others,was found to be the dir line hunting after a movement. This has turned out to be a known problem with the pru and the fact it is using position feedback and not velocity feedback. So the outcome after a few discussions was that the hal file needs changing to utilise the stepgen in velocity mode. Now i am at a complete loss how to do this,so is there anyone out there that can help? Charles is snowed under at the moment otherwise i am sure he would oblige. I will try attatching my hal file. I am sure there are others that will explain this better than me because of my limited knowledge. -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Crackling motors using Beaglebone
Peter's solution will work. I was going to add a dead-band to the PID control internal to the HAL component that talks to the PRU, but Peter's suggestion of pushing the PID outside the PRU driver and into HAL makes a lot more sense. The existing HAL PID component is vastly more sophisticated than the PID inside the PRU driver, and pushing it out into HAL not only makes the configuration more unix and LinuxCNC like, but doesn't require any new code to implement. I just don't have time to play with HAL right now (I'm getting ready for a 100K run this weekend), and my test machine is currently in various pieces so I couldn't check things out even if I had time to make the change. I can probably get to it next week sometime, but I'm hoping someone will beat me to it. On 2/20/2014 11:19 AM, Jeff wrote: Hi, I looked at the DIR line on a bare beagle bone with no attachments. The DIR line can end up toggling after a move has stopped. But it does not *always* end up toggling after a move. Pressing the power button in AXIS clears the situation until a future move. The STEP line does remain inactive, so there is no unwanted movement. Mark is using Geckos which are optically isolated, so the chance of electrical noise contributing to the problem is unlikely. I've also noticed the problem with the Allegro A3977 drive chips. I'm not sure why either the Geckos or the A3977 would care about a toggling DIR line while STEP is inactive, but they do. Perhaps it is some kind of noise issue within the drive itself (i.e. not electrical in the wiring/grounding sense). In any case, the solution (when found) will be to stop the line from toggling at all. Hopefully Peter's suggestion of a different HAL configuration will work. Jeff Date: Thu, 20 Feb 2014 16:53:07 + From: m...@rmtucker.f2s.com To: emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Crackling motors using Beaglebone The drivers have been working on mach3 for the last 5years with no problem,and also work no problem with linuxcnc on a pc. I believe jeff pollard has scoped the output on the dir line and it is clearly visible. On 20/02/14 16:43, Josiah Morgan wrote: Mark, when this happens, have you tried unplugging the step and dir(everything but enable) from the beaglebone to verify that it isn't just coming from microstepping on the driver itself? I know I've experienced similar crackling sounds on some stepper drivers that was completely isolated from input from step/dir source. On Thu, Feb 20, 2014 at 10:21 AM, Mark Tucker m...@rmtucker.f2s.com wrote: Ok i am not well enough conversed to explain this in detail,but i will try. Having recently been involved with the beaglebone/machinekit setup,i accidently came across a problem. I found that speradically the motors would make a noise like frying an egg after movement had finished. This after some investigation by Charles,Jeff pollard,and few others,was found to be the dir line hunting after a movement. This has turned out to be a known problem with the pru and the fact it is using position feedback and not velocity feedback. So the outcome after a few discussions was that the hal file needs changing to utilise the stepgen in velocity mode. Now i am at a complete loss how to do this,so is there anyone out there that can help? Charles is snowed under at the moment otherwise i am sure he would oblige. I will try attatching my hal file. I am sure there are others that will explain this better than me because of my limited knowledge. -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https
Re: [Emc-users] Crackling motors using Beaglebone
On 02/20/2014 12:01 PM, Charles Steinkuehler wrote: Peter's solution will work. I was going to add a dead-band to the PID control internal to the HAL component that talks to the PRU, but Peter's suggestion of pushing the PID outside the PRU driver and into HAL makes a lot more sense. I might mention that I have to use deadband with the Pico universal stepper controller, as it uses the traditional PID and the step generator is velocity only. This allows the board to be used with either open- or closed-loop stepper setups with minimal change. Jon -- Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121054471iu=/4140/ostg.clktrk ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
