Messages

1

HiCON Motion Controller / Re: HiCON 7766 Linear Encoder vs. Easy Servo (Leadshine)

« on: April 17, 2018, 06:52:47 PM »

Thanks for the replies.

The reason for two loops is reliable coordinated motion. The outer loop manages the axis relative to desired position, and the inner loop manages the motor relative to commanded position. I realize that most conversions don't employ this.

In the case of the Leadshine drives, they're more like servos than open-loop steppers. The power-to-output is significantly more efficient as well. And cost per power (at accuracy) is significantly less than any servo system. So I'm going to stick with this.

VSI Support:
Can you expand on your statement? I'm not sure I fully understand this:

With closed-loop option, HiCON controller corrects any position error (eg ballscrew non-linearity error) at the start of the next move.  The correction does not happen on every control-loop cycle.

Can you please define the terms "Move" and "Control Cycle"? I want to be sure I'm interpreting correctly.

Thanks!

2

HiCON Motion Controller / Re: HiCON 7766 Linear Encoder vs. Easy Servo (Leadshine)

« on: April 15, 2018, 05:48:14 PM »

Here's another diagram showing my "case 2" wiring and loops

3

HiCON Motion Controller / Re: HiCON 7766 Linear Encoder vs. Easy Servo (Leadshine)

« on: April 15, 2018, 05:25:16 PM »

Here's a diagram showing my "Case 1" wiring from the above post.

4

HiCON Motion Controller / HiCON 7766 Linear Encoder vs. Easy Servo (Leadshine)

« on: April 15, 2018, 03:43:19 PM »

Hi

I'm weighing the pros and cons of closed loop operation with the 7766. Can you guys check my assumptions here?
I am planning Leadshine 3-phase AC Easy Servos in my machine setup, and am converting a Weiss 32.

Case 1: Employ absolute linear scales, feeding back to the 7766.
  - If I understand correctly, this should be the tightest loop possible, with the most accuracy and repeatability.
  - It should also effectively negate any ballscrew non-linearity, since the ballscrew would be "inside" the motion loop.
  - I suspect as a con that the resolution of the steppers is the limiting factor for accuracy, effectively degrading the scales.
  - I *think I lose the force vectoring function of the Easy Servos, since I presume I can't employ both loops simultaneously.

Case 2: Direct the Easy Servo Motor encoder feedback to the 7766.
  - This appears to be a HiCon supported configuration, and it looks like the breakout boards are compatible with the Leadshine drives.
  - This will require external drive mapping to correct non-linearity.
  - I'm confused about whether this allows the closed-loop force vectoring functions of the Leadshine to be used simultaneously to the 7766 closed loop functions.

Can you guys give me any advice?

Thanks
P