Axis drives

I am learning about single and Multiple axis drives. I googled for books/ material online..no luck.

can someone tell where i can find related material. how to program single and multiple axis drives using PACs..when do i pick single axis drive and when do i pick multiple axis drive.

thanks all
- Fresh Grad

bioplc said:

when do i pick single axis drive and when do i pick multiple axis drive.

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Are you sure you really want to ask this question?

bioplc said:

when do i pick single axis drive and when do i pick multiple axis drive.

thanks all
- Fresh Grad

Click to expand...

I agree with Norm, but I will try to help.

1. Do you have a SINGLE motor or MULTIPLE motors?
2. If you have a SINGLE motor, do you every intend to have MULTIPLE motors?
3. Does upfront cost or incremental cost mean something to you?

Just my thoughts on the question.

ok,earlier question sounds too dumb...i rephrase my question...lets say i need only 3 axes servo drive for current project...do i have to keep future developments in mind???

Since this is a PLC forum, I'll talk about motion control modules that reside in a PLC. A single axis motion control module takes up one PLC slot and controls one servo axis. A dual axis motion control module takes up one PLC slot and can control two servo axes.

Advantage one for the multi-axis module: It uses up less physical space.

Details vary from one brand of PLC to another, but it's a pretty good bet that it's easier to slave one axis to another when both axes are controlled by the same module.

do i have to keep future developments in mind???

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No, you don't, but if you know the system is going to change in the future, you'd be foolish not to.

Steve covered the controller aspect pretty good. From the Drive perspective there are also considerations that can be had.

There are stand alone drives which take in the mains power and control a motor or two.

Then there are what I would call "bus-able" stand alone drives that can stand alone but can also have their DC busses connected with other drives. The advantage to this is that they can share regen capability or the ability to electrically brake overrunning loads. For instance vertical axes usually go into regen when quickly lowering loads. If you have a three axis system (X, Y, Z) but Y & Z don't have any regen you can handle as much regen as all three drives are capable of for the Z axis.

Each of the above has to have a power conversion section that rectifies the AC to make DC.

There are also systems with a main power supply that does the AC -> DC conversion and can have multiple drives hooked to its DC bus. The power supply is an extra component but then each drive is less expensive because it only need to have the motor driving circuits, not the AC->DC part. Some of these power supplies can actually put regenerated power back onto the mains supply lines and save energy vs. dumping the regen over a resister and making heat.

Recently, there are motors that have the drive built into them. These are generally smaller motors but then you can expand the system without adding anythign to the main electrical enclosure. Dunkermotoren has some small DC servo motors like that http://www.dunkermotoren.de/default.asp?lang=2

Bosch Rexroth has some AC servos that are a little larger with built in controllers. http://www.boschrexroth.com/busines...antriebstechnik_en/indradrive_mi_en/index.jsp

There is where you can have a truly expandable system...

<disclaimer> I work for a company that distributes both Dunkermotoren and Bosch Rexroth products</disclaimer>

bioplc said:

when do i pick single axis drive and when do i pick multiple axis drive.

Click to expand...

As stated above, it is cheaper to use a multi-axis system that multiple single axis sytems but do you have to move these axes simultaneously? If you have to do interpolation between axes to achieve the movement path you want (e.g. cutting at an angle or a radius on a CNC machine) then you have no choice but to go multi-axis.
Only time I could see an advantage from single axis systems would be if you were using one large control system to control several small machines. You would only lose the use of one machine while waiting for a drive to be repaired in that scenario.