Resolution external encoder

We are revamping an older packaging machine (new plc, new drives).
At the end of the machine there is a belt that synchronises with a belt of another machine. A 1024 ppr TTL encoder is mounted on the external belt, we have no setpoint information of the external machine. The external belt is Always running at constant speed.The external belt is running at 366 mm/sec or 110 rpm.
This would lead us to 7.5 increments / ms.
Servocycle of our motion controller will be 2 or 3 ms (still to decide), this makes 15 to 22.5 increments per servocycle.
The slave belt will be synchronised in a 1 to 1 ratio with the master belt, so alse 366 mm/sec. In the old program the slave synchronised over a slave distance of 25 mm. This would lead to
an acceleration of 2679 mm/s² considering constant acceleration. There is also a mode where the slave has to catch in an then sychronises in a 2 to 1 ratio, but over the same slave distance. This would lead to 10716 mm/sec².
Our slave servomotor has a 20 singleturn encoder that is used for position control.
Is the resolution of the external encoder (1024ppr) sufficiënt for the gearing we want to accomplish here (stability)?
Thanks

Is it a 1024 line encoder, or a 256 line encoder? In other words, hoping your encoder input is quadrature. 1024 line encoder = 4096 PPR post quadrature.

Highland Controls said:

Is it a 1024 line encoder, or a 256 line encoder? In other words, hoping your encoder input is quadrature. 1024 line encoder = 4096 PPR post quadrature.

Click to expand...

It is 1024 ppr, so the motion controller sees 4096 increments per rotation. But the question was, is this enough for the given situation?

OK, I see that is accounted for in your math. What is a "20 singleturn encoder"?

20bit single turn encoder.

aand74 said:

Is the resolution of the external encoder (1024ppr) sufficiënt for the gearing we want to accomplish here (stability)?
Thanks

Click to expand...

Yes, but that depends on how you tune it and how much error you are willing to put up with between the slave and master.


Once the slave is in sync with the master everything should be OK but I don't think the ramps to sync speed will be pretty.


Much depends on the slave motion controller and what options it has for estimating the velocity of the master accurately.


If I were doing this I would use an alpha-beta-gamma filter to estimate the master's position, velocity and acceleration so that the slave can use them for feed forwards.


Ramping up gearing from 0 to 1 to 1 to 1 is best done if the chain rule is used. This was discussed a little in another recent thread.