On Tue, Jul 8, 2014, at 10:30 AM, Viesturs Lācis wrote: > 2014-07-08 15:13 GMT+03:00 John Thornton <[email protected]>: > > And I might add that the thc component will only work with steppers due > > to the hijack/lying about position stuff. > > Only in it's current form. IMHO it is easy to adjust it for servos. > There was a servo motor on Z axis for my last plasma machine build and > what I did: > 1) adjusted thc component so that it exports calculated offset value > to a HAL pin; > 2) adjusted kinematics module: > a) added HAL pin, which was connected to thc.offset > b) adjusted forward and inverse kins calculations, so that joint.2 = > pos.x + thc.offset >
I believe Jeff Epler wrote a HAL component years ago to do just this. I'm not at a Linux box right now, but I think it might be called "offset". It adds a value to the outgoing position command, and subtracts the same value from the incoming position feedback. It is intended to be installed between motion and either the PID loop (servo) or the stepgen (stepper). The other half of the equation, accel and velocity limiting, also has a ready-made HAL component, limit3. The offset from the THC goes into limit3, and even if it instantly steps, the output of limit3 obeys acceleration and velocity limits. That output would then go to the offset block. -- John Kasunich [email protected] ------------------------------------------------------------------------------ Open source business process management suite built on Java and Eclipse Turn processes into business applications with Bonita BPM Community Edition Quickly connect people, data, and systems into organized workflows Winner of BOSSIE, CODIE, OW2 and Gartner awards http://p.sf.net/sfu/Bonitasoft _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
