Synchronizing 2 motors in phase and speed

[leitmotif]

Peter said
But this is easy to do if you know how and have the right tools

Isnt that the truth!!!! The learning curve to get there is to say least interesting.

I find it interesting that Damien has posted only twice (??) I would like to know what the process is to get better understanding of why the need.

 

[Manglemender]

I have done phase gearing in a PLC but it isn't well suited to the task, you really want a motion controller. Some drives can do phase gearing on their own such as the SSD690+ drives fitted with a system board. The ATV71 drives have a processor board that can be fitted - not sure if it can do phase gear and also not sure if it can be fitted to the ATV31.

Nick

 

[damianr]

Sorry for been not answering, I was ill at bed for the last 10 days. Thanx so much for all the tips. I will post more info on what im doing......And sorry if my english is not the best and been misunderstood

 

[damianr]

Here is the deal, hope this help…….
I have one machine, a packing one, that was done by other people. This one packs sugar, the small packs for a coffee shop
The other one, puts 12 packs in a box and then this box is closed and finished.
The first machine has its own motor and encoder for all the movements and control needs.
From this machine, the only information I have is a digital PLC Output that is in logical 1 from 0 to90º of its encoder and from 180 to 270º, the others 180º this output goes to logical 0.
On the second machine, MINE ONE, I would read that output on one of my inputs and do the maths to calculate speed, I know that in a T time, that motor has rotated 90º so I can calculate the speed.
Made something similar in MY PLC (with my encoder) to compare both windows of measurement and then I can take an action on MY motor, I cannot change speed of the first machine.
I have an analog output to control the ATV, and my idea is to change this value to reach main machine speed.
Synchro MUST be done in 720º (we call a 360º rotation of the packing machine a HIT, where all mechanical movements are done to have one pack at the output), so I have 2 hits to do the synchro.
They MUST be at the same speed because in MY machine I have some mechanical movements, not controlled with the PLC, that need to be in synchro with the main speed (that can be changed)
Phase synchro: Only thing I need is that them both get in phase, no matter if the first encoder is in 48º and the second in 150º, but what matters is that they have this values ALWAYS at some point of view (this is where I look for it in a window).
Hope this would be more clear for everyone, to try helping me
THANX A LOT TO ALL OF YOU GUYS!!!!!

 

[DickDV]

The phase synchronization requires at minimum an absolute encoder on both motors. Then a rotational position controller to synchronize the two motors in rotary position.

This is out of my league! Sounds like a servo job to me!

 

[Peter Nachtwey]

Easy

Phase synchro: Only thing I need is that them both get in phase, no matter if the first encoder is in 48º and the second in 150º, but what matters is that they have this values ALWAYS at some point of view (this is where I look for it in a window)

This is easy. We have an Advanced Gear Move command where the user specifies where the slave motor is to be in sync (TBD ), the gear ratio ( 1 to 1 ), gear ratio rate of change ( 0 ), the master target position, the master sync (TBD ) position, the master direction ( 0 ) and the slave direction ( 0 ). Now if you want the two motors to be geared 1 to 1 at 360˚ you enter 360˚ for both the master and the slave sync positions. The slave will travel from 48˚ to 360˚ at the same time the master travels from 150˚ to 360˚. The the first encoder is the master just change the two sync position parameters. As a rule the slave should move half as far as the master if the slave speed isn't to exceed the speed of the master.

Example:
Use the IEC Clutch by Distance command. If you know the slave can ramp up in 30˚ then you also know the master will travel 60˚ in the same time. In the Clutch by Distance command you specificy the gear ratio ( 1 to 1 ), the master and slave sync positions and the master start distance ( 60˚ ). After issuing this command the motion controller waits until the master is within 60˚ if its start position and then the slave starts to ramp up to its sync position while the master moves to its sync position.

In your case the slave is at 150˚ while ramp up to the master speed in 30˚ so the sync position is 180˚ for both the master and the slave. The master will move till it gets to 120˚ ( 180˚-60˚ ) and keep going but that will trigger the slave to ramp up from 150˚ to 180˚ degrees in the same time.

17 bit SSI encoders would be best. It is best to gear to high resolution masters.

 

[kamenges]

Originally posted by Peter Nachtwey:

This is easy.

...if you are using the right tools.

What Peter neglected to mention is that you won't be doing this kind of thing in an MicroLogix 1400. His example was based on using a controller that supports motion commands. You also need much better feedback than you currently have.

The moral of the story is you will very likely not be able to do what you are asking with the devices you have to work with.

Keith

 

[damianr]

Ok, I´m really thinking about opening a greengrocery instead of programming this machine