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 > [email protected] > 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
