Positioning Mode (Point Table Methode) Using Servo

[Verdy Adelwin Mahmud 0]

Hi, I have a system using Mitsubishi servo MR-J4-350A-RJ. This servo is used to pull the printing paper. To set the pull, using the points table in the MR Configurator program.

What should I set in this servo?

[JRoss 84]

Not much information to go on here. You'll need to provide a lot more information about the application before you can expect any useful answers.

[Verdy Adelwin Mahmud 0]

Oke, I have information like this :

1. Servo Amplifier : MR-J4-350A-RJ
2. Servo Motor : HG-SR352
3. Roller : 695.5 mm
4. Pulley On roller : 3
5. Pulley On Servo Motor : 2
So, ratio pulley = 3 : 2

Servo is used to pull the paper.  This paper used to print labels.
I want to pull the servo in accordance with point table.

Example : I set target position on point table at 30mm (if set the mm). But now I used pulse
 

 

[Luke.S 8]

The J4 series have a 22 bit encoder. That's 4,194,304 pulses in one revolution of the motor.

The motor rotates 1.5 times for one rotation of the load. That's 6,291,456 pulses.

The load has a feed distance per one revolution of 3.14159..x695.5 = 2184.977691mm (assuming you gave us the roller diameter above). Therefore the number of pulses required to feed 1 mm is 6,291,456/2184.977691=2879.

Take your target feed value in mm from e.g. HMI and multiply it by 2879 (signed bin32) and send that to the drive.

[Verdy Adelwin Mahmud 0]

Hi Mr Luke.

I was a little correction.
Roller = 695.5mm, It's arround

Then, how do I get this value 3.14159 ?
That 's phi ?

 

Edited 13 Jun 2016 by Verdy Adelwin Mahmud
Wrong statement

[Luke.S 8]

Yes that is pi π.

The circumference of the roll is pi x roll diameter. The circumference = feed of one roll revolution.

Sorry if I misunderstand you but do you mean 695.5 is the circumference?

 

[Verdy Adelwin Mahmud 0]

17 hours ago, Luke.S said:

Yes that is pi π.

The circumference of the roll is pi x roll diameter. The circumference = feed of one roll revolution.

Sorry if I misunderstand you but do you mean 695.5 is the circumference?

 

Oke Thanks Mr.Luke.
Yes, the value 695.5 is the circumference...

So, the calculation is
6,291,456 / 695.5 = 9045.946800862689mm right?
 

[Luke.S 8]

Yes. ~9046 pulses are required to move 1mm. It might not actually work that way though. You might need to tune the drive to improve steady state error, the paper could slip on the roll etc.

[Verdy Adelwin Mahmud 0]

Hi, MR. Luke.
I need your help, please see my videos. I attach 3 part video.
This servo pull 49mm. The sign of the sensor does not correspond.

 

Part 1.mp4

[Verdy Adelwin Mahmud 0]

Just now, Verdy Adelwin Mahmud said:

Hi, MR. Luke.
I need your help, please see my videos. I attach 3 part video.
This servo pull 49mm. The sign of the sensor does not correspond.

 

Part 1.mp4

 

Part 2.mp4

[Verdy Adelwin Mahmud 0]

Just now, Verdy Adelwin Mahmud said:

 

Part 2.mp4

 

Part 3.mp4

[Verdy Adelwin Mahmud 0]

Please see the image..

[Luke.S 8]

Hi. What is the problem? The feed is too long? Too short? Or does it change every positioning operation?

[Verdy Adelwin Mahmud 0]

Mr. Luke,
I have two method.
First, not using sensor. This print using more colour (1-4 colour).
Second, using sensor. This print using 1 colour. Sensor mode is second printing from first method.

The first method, sometimes it change every positioning operation.
Example : I give two condition, bad and good. When the operation run.
I found the printouts like this : good, good, good, good, good, bad, bad, good, good, good, bad, good, good, good, bad, good, bad, good, good.
It's random between bad and good.

The second method using sensor, the feed is too long like my video.

I'm very confuse about this operation, I dont know there is a problem in the mechanical or servo program.
I hope you understand with my explanation.
 

[Luke.S 8]

It is possible that a small amount of steady state error (or droop pulse) is being built up over a few cycles. This will be small but eventually will be big enough that you get a "bad" feedback. You could try decreasing the speed of the positioning operation and see if that improves it. If so you need to tune the positioning loop to improve steady state error. Auto tuning might help. You can do this in MR Configurator and there are graphing functions to help you see the response.

Mechanically there may be backlash in the gears/pulley which can also be compensated for in MR Configurator. Is it being fed by a nip roll? The substrate might be slipping on the roll and you need to make sure there is good contact with the nip. There are other possibilities as well which should be discussed with the mechanical engineer.

Or there could be a small error in number of pulses per mm that was calculated.