Two encoders/motors one following the other.

[dave_nicnz]

Hey, i have a Omron CP1l with two encoders and am after some advice onn what commands to use for a simple follow me type motor control.

the primary motor is driven independently and we have attached a encoder to this, we then want tell our motor with a 0-10v output from plc how fast to go to maintain the same encoder pulses as the input encoder, matching encoder for encoder

Both motor are rotational/speed not linea if that make a differnce.

thanks in advance

 

[JoanM]

You are searching for a "Flying saw" sync it by speed or position depending on your needs.

I've never worked with Omron, but the concept will be the same.

Good luck!

 

[rdrast]

How much accuracy do you need?
For something simple, you can use a controller like a low end Contrex MTrim, for more accuracy and flexibility, Contrex has a higher end controller, the CX series, sounds like you might want a CX-1010 type.

If you need precise control always, you will probably have to look at a high end motion controller like an RMC-75 from Delta.

 

[osmanmom]

what type of application ?

 

[dave_nicnz]

hey, yeh a flying saw would be similar, the application is actually a rope like product being produced on one machine (spinning as it is extruded) and our machine will wind this onto a drum, so has to rotate the drum at the same speed as the rope is being made, and wind up keeping taut between the two machines(this is done mechanically as a function of the rotation) different size ropes rotate at different speeds, we have a binary switch input to the plc for the 8 sizes. accuracy is important as we dont want the product over or under twisting as its rolled onto a drum. (there is inch fwd and back buttons to compensate for minor adjustments)
at the moment i have 1 encoder "filling a bucket" and the other "emptying" with the "fullness of the bucket" being the 0-10v output to the dc speed drive.....
about to do a real life test so will see if its going to work.....

 

[rdrast]

Would not a simple dancer work for the takeup?

Use a loaded dancer (either weights or air) to set your product tension, and control the takeup drum speed via dancer position.

 

[dave_nicnz]

The take up is not the issue, (winding up the drum) the issue is rotating the entire drum(while its winding up) to match the speed of the rope twisting as it comes off the first machine. Thanks tho

 

[rdrast]

Ahhhh, okay, got you. Like a cabler. Then one of the Contrex devices should work fine as a controller for a reasonable cost, and easy programming.

 

[OkiePC]

I have seen an application like this (string spiral wrapping around extruded rubber coated steel tire bead wire ribbons) that was so simple and if scaled right, it was accurate enough for us. They wanted a strip every so many inches within about 1/2" and it would do that. It had an encoder something like 1000 ppr wired to a Wilkerson Instruments freq to voltage converter which was wired to the vfd controlling the spinning cage wrapping string around a strip of extruded rubber that varied in speed from zero to 400 fpm. There was not much to it, a start stop signal and a door switch to put it in auto mode, all hard wired, reliable and simple. The encoder was surface driven, and the converter was reliable and precise for a simple follower. It was originally wired to DC drives and we did go up a bit in HP with AC drives and got good performance, not perfect, if you need perfect, you need a motion controller, if you need electronic gearing exact position at all speeds, you need at least a good programmable drive with follower options.