Re: [Emc-users] help with torch height control
Short reply is - the THCUD does not work for servo loops but is designed for stepper systems. You will have to look at rolling your own control and for servos that might take some doing. The general consensus is that you axis of a plasma. Most systems use a standalone THC system that drives the Z axis independently of the motion controller. Most of them use a stepper or a dc motor with position feedback. I am sure that you could put together a system that uses a PID loop in linuxcnc and use that to control the THC function. On 2015-01-12 13:49, lloyd wilson wrote: We are trying to adapt our Techno router (servo, not stepper) to use a plasma torch I'm having some difficulty understanding how to utilize the thcud hal component. Conceptually, it seems simple: the component sits between the axis and pid modules of the z axis and adds a correction to the commanded z height as dictated by the torch height controller. I've plumbed the thcud component into the system config files and built a simulator to mimic the thc box (up, down, arc OK inputs). All the IO appears to be working properly, but I see no altered Z heights when exercising the inputs. Some questions from reading the component documentation source: - the thcud component generates a position feedback value to be fed back to the motion component, but the 'normal' servo configuration sends position data from the encoder function to both the pid component and the motion component. What is the consequence of decoupling the two feedback inputs? - in the code, I don't see where either of the parameters (velocity_tol and correction_vel) are initialized. Is that somehow done behind the scenes? Or does it need to be done in the hal files? - Also, why is the velocity tolerance divided by 100 in the code? As I read the man page, the pyvcp spin box value should associate with the tolerance parameter, but the spin box input is already limited to a max of 1 - looks like it's taking a percentage of a percentage. At a more expedient level, can someone point me to a functional servo-based configuration that uses the thcud component? As always, upfront thanks for the help -ldw -- New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. vanity: www.gigenet.com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Regards /Groete Marius D. Liebenberg +27 82 698 3251 +27 12 743 6064 QQ 1767394877 -- New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. vanity: www.gigenet.com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] help with torch height control
On 2015-01-12 16:42, andy pugh wrote: On 12 January 2015 at 14:33, Marius Liebenberg mar...@mastercut.co.za wrote: he general consensus is that you dont use servos on the Z axis of a plasma. I am not part of that consensus. I see absolutely no reason to prefer any motor type over another in this application. Its not the motor type that is problematic but rather the control. I am in agreement that one could control the servo just as well if not better, it has just not been done on LCNC at his time. Most of the THC hardware out there is done for steppers or in the case of a standalone controller also a dc motor option. It is on my long list of things to do as I am moving my preference towards servos as they get more affordable all the time. :) What makes it problematic ids that one has to use Gcode and once the system is running you reference (the job zero) changes. This is opposite to normal behaviour and breaks the rules. Now one has to start creating cnc controller situations that are not realistic and is not catered for in the normal running of things. The most successful systems are indeed the standalone controllers that get simple signals from the motion controller and does its own thing from there onward. I am of the opinion that one can do the standalone controller in LCNC but just not part of the motion loop. -- Regards /Groete Marius D. Liebenberg +27 82 698 3251 +27 12 743 6064 QQ 1767394877 -- New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. vanity: www.gigenet.com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] help with torch height control
On 12 January 2015 at 14:33, Marius Liebenberg mar...@mastercut.co.za wrote: he general consensus is that you dont use servos on the Z axis of a plasma. I am not part of that consensus. I see absolutely no reason to prefer any motor type over another in this application. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. vanity: www.gigenet.com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] help with torch height control
sorry there are some words missing. This is what I meant to say. The general consensus is that you dont use servos on the Z axis of a plasma. On 2015-01-12 16:22, Marius Liebenberg wrote: Short reply is - the THCUD does not work for servo loops but is designed for stepper systems. You will have to look at rolling your own control and for servos that might take some doing. The general consensus is that you dont use servos on the Z axis of a plasma. Most systems use a standalone THC system that drives the Z axis independently of the motion controller. Most of them use a stepper or a dc motor with position feedback. I am sure that you could put together a system that uses a PID loop in linuxcnc and use that to control the THC function. On 2015-01-12 13:49, lloyd wilson wrote: We are trying to adapt our Techno router (servo, not stepper) to use a plasma torch I'm having some difficulty understanding how to utilize the thcud hal component. Conceptually, it seems simple: the component sits between the axis and pid modules of the z axis and adds a correction to the commanded z height as dictated by the torch height controller. I've plumbed the thcud component into the system config files and built a simulator to mimic the thc box (up, down, arc OK inputs). All the IO appears to be working properly, but I see no altered Z heights when exercising the inputs. Some questions from reading the component documentation source: - the thcud component generates a position feedback value to be fed back to the motion component, but the 'normal' servo configuration sends position data from the encoder function to both the pid component and the motion component. What is the consequence of decoupling the two feedback inputs? - in the code, I don't see where either of the parameters (velocity_tol and correction_vel) are initialized. Is that somehow done behind the scenes? Or does it need to be done in the hal files? - Also, why is the velocity tolerance divided by 100 in the code? As I read the man page, the pyvcp spin box value should associate with the tolerance parameter, but the spin box input is already limited to a max of 1 - looks like it's taking a percentage of a percentage. At a more expedient level, can someone point me to a functional servo-based configuration that uses the thcud component? As always, upfront thanks for the help -ldw -- New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. vanity: www.gigenet.com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Regards /Groete Marius D. Liebenberg +27 82 698 3251 +27 12 743 6064 QQ 1767394877 -- New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. vanity: www.gigenet.com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
[Emc-users] help with torch height control
We are trying to adapt our Techno router (servo, not stepper) to use a plasma torch I'm having some difficulty understanding how to utilize the thcud hal component. Conceptually, it seems simple: the component sits between the axis and pid modules of the z axis and adds a correction to the commanded z height as dictated by the torch height controller. I've plumbed the thcud component into the system config files and built a simulator to mimic the thc box (up, down, arc OK inputs). All the IO appears to be working properly, but I see no altered Z heights when exercising the inputs. Some questions from reading the component documentation source: - the thcud component generates a position feedback value to be fed back to the motion component, but the 'normal' servo configuration sends position data from the encoder function to both the pid component and the motion component. What is the consequence of decoupling the two feedback inputs? - in the code, I don't see where either of the parameters (velocity_tol and correction_vel) are initialized. Is that somehow done behind the scenes? Or does it need to be done in the hal files? - Also, why is the velocity tolerance divided by 100 in the code? As I read the man page, the pyvcp spin box value should associate with the tolerance parameter, but the spin box input is already limited to a max of 1 - looks like it's taking a percentage of a percentage. At a more expedient level, can someone point me to a functional servo-based configuration that uses the thcud component? As always, upfront thanks for the help -ldw -- New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. vanity: www.gigenet.com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] help with torch height control
On 12 January 2015 at 11:49, lloyd wilson llwilso...@rochester.rr.com wrote: built a simulator to mimic the thc box (up, down, arc OK inputs). All the IO appears to be working properly, but I see no altered Z heights when exercising the inputs. Where are you looking? You won't see any height change on the screen. If you put a halmeter on the PID position command you should see some activity. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. vanity: www.gigenet.com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] help with torch height control
On 12 January 2015 at 14:58, Marius Liebenberg mar...@mastercut.co.za wrote: Its not the motor type that is problematic but rather the control. I am in agreement that one could control the servo just as well if not better, it has just not been done on LCNC at his time The thcud component doesn't know or care whether it sits between motion and a stepgen or motion and a pid. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. vanity: www.gigenet.com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] help with torch height control
On 2015-01-12 17:33, andy pugh wrote: On 12 January 2015 at 14:58, Marius Liebenberg mar...@mastercut.co.za wrote: Its not the motor type that is problematic but rather the control. I am in agreement that one could control the servo just as well if not better, it has just not been done on LCNC at his time The thcud component doesn't know or care whether it sits between motion and a stepgen or motion and a pid. Agreed, but as soon as you touch the feedback of the pid loop you get funnies. It could be workable but it seems that most fellows have failed to apply it to servo systems. The process needs some lots of work :) -- Regards /Groete Marius D. Liebenberg +27 82 698 3251 +27 12 743 6064 QQ 1767394877 -- New Year. New Location. New Benefits. New Data Center in Ashburn, VA. GigeNET is offering a free month of service with a new server in Ashburn. Choose from 2 high performing configs, both with 100TB of bandwidth. Higher redundancy.Lower latency.Increased capacity.Completely compliant. www.gigenet.com ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
