Hello!
I've bought a CNC router in china fitted with the new Yaskawa 7 series (step + direction) servo drives. We installed our own cnc controller (Eding CNC) and are quite happy with the machine so far. I chose to install Eding myself so I can get to know my machine better and use software I am familiar with.

There is one problem with high speed routing: Overshooting.

So I downloaded Sigmawin+ and connected the X and Z axis of my machine, made backups of the setting and run the auto inertia and tuning procedure. For the X and Z axis I uses the autotuning without reference input and it worked nicely so far. The inertia was calculated and on that base the rest of the auto tuning was completed quite fast. Z axis inertia: 1% (ballscrew) X axis inertia: 67% (8:1 reducer and toothrack)

Now for the Y axis, that is a tandem bridge with 2 motors so I must use an external reference input (from Eding) so that the 2 motors are driven. Then auto tune y1 and then y2. There is a catch: I need the inertia load for the motor and the Sigma 7 can only calculate this without a external reference. But that is not possible because without an external reference only y1 would be moving.

How can I acquire the right inertia load or is it possible to let 2 servo's run in tandem in Sigmawin+ so that it can calculate the inertia load by itself?

Other option:
Just guesstimate?
  1. Calculate the weight of the x axis assembly (that has a known inertia ratio)
  2. Calculate the weight of the bridge (then you know the inertia ratio?)
  3. Add up the two for the total inertia ratio of the bridge and X axis assembly
  4. divide by 2 because there are 2 motor driving the bridge


Hoping to hear from you guys!