Smart Steppers

[alexo]

The cheapest option for an accurate encoder is to purchase a small Mitsubishi servo motor off eBay. Some come with a 1 million line encoder. Cheap as chips compared with buying the encoder by itself and already nicely mounted in a precision enclosure. Works a charm.

Yeah, for the most part stepper are open loop units and if you're going to need closed loop servo's are a better choice for a number of reasons.  Servos do not need the holding torque as they have the encoder to know if it moved -- a stepper needs to have a fairly high holding torque so it knows it hasn't moved else it loses counts.  Holding torque requires more power and produces more heat.  Servo's are much smoother and quieter as well.

For position critical applications you might have two encoders: one on the motor to close the velocity loop and one on the load to close the position loop.


Brian


Brian

Stepper systems are superior to servos but for the case of highly variable heavy loads.

Yeah, no..

Show me any commercial robot that uses steppers versus AC or DC servos.  Steppers require more power on average and produce more heat and are noisier.  It what ways do you view steppers as superior?


Brian


brian

Well, there are MANY. Too many to bother mentioning.
Now, factor into your post my " but for the case of highly variable heavy loads".

[Mechatrommer]

with closed loop, holding torque current for stepper motor can be released, only engaged when motor position is changed, just like normal servo/dc motor. the superiority of stepper is it can be used as position control in open loop, given miss step can be prohibited... long story short... it can be googled...

[raptor1956]

The cheapest option for an accurate encoder is to purchase a small Mitsubishi servo motor off eBay. Some come with a 1 million line encoder. Cheap as chips compared with buying the encoder by itself and already nicely mounted in a precision enclosure. Works a charm.

Yeah, for the most part stepper are open loop units and if you're going to need closed loop servo's are a better choice for a number of reasons.  Servos do not need the holding torque as they have the encoder to know if it moved -- a stepper needs to have a fairly high holding torque so it knows it hasn't moved else it loses counts.  Holding torque requires more power and produces more heat.  Servo's are much smoother and quieter as well.

For position critical applications you might have two encoders: one on the motor to close the velocity loop and one on the load to close the position loop.


Brian

Stepper systems are superior to servos but for the case of highly variable heavy loads.

Yeah, no..

Show me any commercial robot that uses steppers versus AC or DC servos.  Steppers require more power on average and produce more heat and are noisier.  It what ways do you view steppers as superior?


Brian

Well, there are MANY. Too many to bother mentioning.
Now, factor into your post my " but for the case of highly variable heavy loads".

I posted a number of factors favoring servos so perhaps you could be so kind as to offer a few examples where steppers are superior?  Yes, if positioning is not as critical steppers are the way to go and I've designed a number of systems using steppers so I'm not biased against them.  If the op is looking to add an encoder it would suggest to me a concern that a stepper alone might lose position.  Again, in a positioning critical application servos smoke steppers! 

I await your list is reasons why steppers are superior...


Brian

[alexo]

I have been working on making stepper motors smart. That is adding a rotary encoder and then setting up the stepper motor as a closed loop servo.   The design is such that you can retro fit your existing stepper motors and upgrade your machine.

Many people are using the NEMA 17 units to fix their 3D printers from missing steps on long prints.  Others are using the NEMA 23 on CNC projects and industrial applications.

The way the system works is a magnet is glued (epoxy) to the back of the stepper motor shaft, then the PCB is bolted to the back of the stepper motor which senses the rotation angle of the magnet.  The Smart Stepper PCB has a motor driver, and a 48Mhz 32bit processor allowing full closed loop control. Once the PCB is attached you disconnect motor from machine and run through a calibration process. Then you interface the Smart Stepper to your existing controller using the step and direction pins (if you use step stick you can remove them from your controller).  At this point you select what microstepping you want and you are off and running. The motor should run quieter and will faster (if you increase speed on controller).   

The software allows you to select multiple modes of operation, from a simple PID mode which works for most people out of the box, or a positional PID which requires more tuning but gives better performance.  For other applications you can select velocity operational modes too.  Of course the software is all open source and you can  change it as you like. 

I have setup a website where you can get your smart stepper kit to upgrade your stepper motors here:
http://misfittech.net/smart-steppers/

Thanks
Trampas

Have you looked at things like these :

http://www.ebay.com/itm/Hybrid-NEMA23-Integrate-Closed-Loop-Stepper-Motor-Drive-2NM-Position-Encoder-36V-/121792648966?hash=item1c5b685706:g:aEoAAOSwqVBZYfN~


http://www.ebay.com/itm/NEMA23-3N-m-3phase-easy-servo-Closed-loop-stepper-motor-drive-kit-CNC-DC20-50V-/172690310642?epid=905996634&hash=item28352505f2:g:HAAAAOSwGJlZI9rx


They work very well.

[CM800]

The cheapest option for an accurate encoder is to purchase a small Mitsubishi servo motor off eBay. Some come with a 1 million line encoder. Cheap as chips compared with buying the encoder by itself and already nicely mounted in a precision enclosure. Works a charm.

Yeah, for the most part stepper are open loop units and if you're going to need closed loop servo's are a better choice for a number of reasons.  Servos do not need the holding torque as they have the encoder to know if it moved -- a stepper needs to have a fairly high holding torque so it knows it hasn't moved else it loses counts.  Holding torque requires more power and produces more heat.  Servo's are much smoother and quieter as well.

For position critical applications you might have two encoders: one on the motor to close the velocity loop and one on the load to close the position loop.


Brian

Stepper systems are superior to servos but for the case of highly variable heavy loads.

Yeah, no..

Show me any commercial robot that uses steppers versus AC or DC servos.  Steppers require more power on average and produce more heat and are noisier.  It what ways do you view steppers as superior?


Brian

Well, there are MANY. Too many to bother mentioning.
Now, factor into your post my " but for the case of highly variable heavy loads".

I posted a number of factors favoring servos so perhaps you could be so kind as to offer a few examples where steppers are superior?  Yes, if positioning is not as critical steppers are the way to go and I've designed a number of systems using steppers so I'm not biased against them.  If the op is looking to add an encoder it would suggest to me a concern that a stepper alone might lose position.  Again, in a positioning critical application servos smoke steppers! 

I await your list is reasons why steppers are superior...


Brian

I'll offer a bit of insight. I work as an engineer for a motion control distributor, selling, amongst other things, steppers and servos.

Steppers offer the advantage of being lower cost. They also have a higher torque-to-size ratio. If you need low speed, high torque, the cost saving is significant, considering a harmonic drive or planetary gearbox can cost several £££ for a decent quality one.

Naturally, steppers do have their downsides. They have huge issues with resonance. They are far from the most efficient motors and can often have bad documentation for speed / torque curve.

however, as said, they are -very- low cost compared to a good servo system. e.g.


Motor:
- 440mNm
- NEMA 17
- £22

Quality Drive:
- DMD556
- DSP anti-resonance auto-tuning
- 256 Microstepping
- £115

Vs:

Servo motor:
- £55-150

Drive:
- £200-400

Gearbox:
- 50-200


As you can see, the stepper will come out reasonably cheaper, expecially in volume.
Steppers are also plug and play, Servos can need some fine tuning.


I personally favour brushless servos where possible, They are noiseless, much smoother motion and you can get incredible accuracy.

I'm playing around with the concept of building myself a brushless linear motor X-Y-Z gantry for machining. I have my eyes on some nice linear motors and micron encoders sitting in a corner of the warehouse...

[alexo]

I'm not familiar with servos similar to a NEMA17. My usual suspects are between 1 and 4 Kw. Steppers when well matched to the application have very predictable performance, eliminate the need for gearboxes which are high wear items and with proper construction ( Kolmorgen ) and high performances drives are smoother than most servos. Expensive servo systems running pulse and direction will better steppers when used in the right applications. If you get going with your linear servos project I hope you'll keep us informed. I tried those a couple of times and I was never happy. Too much trouble for little performance gain.

[Mechatrommer]

i wonder if any dc/ac motor servo is capable of this speed and accuracy of stepper servo...

[CM800]

i wonder if any dc/ac motor servo is capable of this speed and accuracy of stepper servo...

I'm sorry, I had to take a 5 minute break from reading that just to laugh.

 

How exposed have you been to modern day motion control?

Here is a good application:

Die inspection machine in the semiconductor industry.

They had an encoder tracking at max 6,500,000 counts per second. Throughout all movements, it was within +/- 1 count.

High-end servo drives, such as ones from Elmo Motion Control you get PI current loop tuning with auto-tuning to kick you off.

You can tune position and veloicty with a sine-sweep through the entire operating bandwidth, then tune it live realtime, it even gives you a nichols plot to work with.

Check out this:

https://www.slideshare.net/elmomc2012/elmomc-servo-drive-for-top-performance


Now, mind telling me how a stepper system compares?



 

[alexo]

i wonder if any dc/ac motor servo is capable of this speed and accuracy of stepper servo...

I'm sorry, I had to take a 5 minute break from reading that just to laugh.

 

How exposed have you been to modern day motion control?

Here is a good application:

Die inspection machine in the semiconductor industry.

They had an encoder tracking at max 6,500,000 counts per second. Throughout all movements, it was within +/- 1 count.

High-end servo drives, such as ones from Elmo Motion Control you get PI current loop tuning with auto-tuning to kick you off.

You can tune position and veloicty with a sine-sweep through the entire operating bandwidth, then tune it live realtime, it even gives you a nichols plot to work with.

Check out this:

https://www.slideshare.net/elmomc2012/elmomc-servo-drive-for-top-performance


Now, mind telling me how a stepper system compares?



 

Never exemplify with an exception.
How many industrial milling machines / lathes have you retrofitted ?

[CM800]

Never exemplify with an exception.
How many industrial milling machines / lathes have you retrofitted ?

Not sure what you are talking about there.

I responded to this:

i wonder if any dc/ac motor servo is capable of this speed and accuracy of stepper servo...

To which I can definitely reply that Brushless AC Servos (Linear or Rotary) are superior in both speed and accuracy to stepper servos.

Cost and size benefit is something entirely different, it depends on the machine.

I also guarantee with the correct servo drive and brushless motor you can beat the performance of any stepper servo solution.

However I don't dispute that there can be gains in cost and size with stepper solutions. Though there are big drawbacks with resonant spots.

[alexo]

Never exemplify with an exception.
How many industrial milling machines / lathes have you retrofitted ?

Not sure what you are talking about there.

I responded to this:

i wonder if any dc/ac motor servo is capable of this speed and accuracy of stepper servo...

To which I can definitely reply that Brushless AC Servos (Linear or Rotary) are superior in both speed and accuracy to stepper servos.

Cost and size benefit is something entirely different, it depends on the machine.

I also guarantee with the correct servo drive and brushless motor you can beat the performance of any stepper servo solution.

However I don't dispute that there can be gains in cost and size with stepper solutions. Though there are big drawbacks with resonant spots.

You gave an example which involved a resolution of 4.8nm. That's not relevant. It's also pretty irrelevant to compare high performance servos like say, the Mitsubishi/Omron I commonly use with low cost steppers, the kind eBay is packed with. High performance steppers and drives have very low cogging, almost no resonance issues and have built in holding torque. Next time you retrofit a boring mill you'll see how handy holding torque is and how irritating is to convince a servo system to pretend to have it. In my experience servos cost 2-3 times more in parts only. The dynamic improvement is rarely taken advantage of. I better spend the money on decent ballscrews - those are making a big and very real difference.

[CM800]

Never exemplify with an exception.
How many industrial milling machines / lathes have you retrofitted ?

Not sure what you are talking about there.

I responded to this:

i wonder if any dc/ac motor servo is capable of this speed and accuracy of stepper servo...

To which I can definitely reply that Brushless AC Servos (Linear or Rotary) are superior in both speed and accuracy to stepper servos.

Cost and size benefit is something entirely different, it depends on the machine.

I also guarantee with the correct servo drive and brushless motor you can beat the performance of any stepper servo solution.

However I don't dispute that there can be gains in cost and size with stepper solutions. Though there are big drawbacks with resonant spots.

You gave an example which involved a resolution of 4.8nm. That's not relevant. It's also pretty irrelevant to compare high performance servos like say, the Mitsubishi/Omron I commonly use with low cost steppers, the kind eBay is packed with. High performance steppers and drives have very low cogging, almost no resonance issues and have built in holding torque. Next time you retrofit a boring mill you'll see how handy holding torque is and how irritating is to convince a servo system to pretend to have it. In my experience servos cost 2-3 times more in parts only. The dynamic improvement is rarely taken advantage of. I better spend the money on decent ballscrews - those are making a big and very real difference.

You bring up some good points however you can't seem to take note of WHAT I was responding to, even when I pointed it out once.

I was responding specifically to Speed and Accuracy as related to someone else's post.

You will find some servo drives much better then others. Yes, they are expensive, but with a good understanding of how to set them up, you can get incredible performance.

Don't forget that holding torque only guarantees within a step.

A high resolution encoder on a brushless motor allows it to provide less error with holding torque then a stepper motor.

Elmo drives for example allow gain scheduling for In motion, steady-state and stepping, to allow you to refine motion characteristics.

While I can't argue on cost. I can grantee a better performance using servo motors and drives. (Even better, linear servos)

There is a good reason why virtually all  high end machines use brushless rather then stepper.

You can argue cost all day, but brushless servos simply cannot be beaten in performance.

And FYI, Omeron and Mitsubishi barely hold a candle to Elmo in performance. It blows my mind just what their drives can achieve.

You'll find them used in many high end pick and place machines for example.

check out some of the stuff they can do with gantry [media]https://www.youtube.com/watch?v=Kjl0iyUCeJ8[/media]

Also, they arn't even that much more expensive then competitor drives.

[alexo]

All I can say is that you shouldn't rush to guarantee anything. When it comes to machine tools, retrofits in particular, a single scraped part as a result of improper servo algorithm can ( and often ) costs more than the entire motion system. For 30 years I keep seeing manufacturers advertising and pushing the latest, only to see them a couple of years down the line reverting to the old and trusted. A quick visit to practicalmachinist.com will inform you as to the amount of trouble people have with servos. They're great for certain applications and a pain in others. I know nothing about Elmo and their products. The YT video is cute CGI but there is absolutely nothing new there. Stuff Parker had 25 years ago. In particular when it comes to machine tools one quickly discovers how important is to keep away from the latest fad and stick with the old and trusted. And know. I wouldn't touch Elmo products with a barge pole.   That's because I can not afford to give them a try and discover they're busy that particular week.

Bottom line is this : for "light duty" applications like a 3d printer or the ubiquitous router steppers are 2-3 times cheaper and twice as good. And spending the money on good quality mechanicals for outweighs fancy motors. And another thing : the price of top performance machine tools has become so high that one can sometimes purchase 2-3 lesser units for the price of a single high perf one.  Lots of people wised up to this one.

Deep down dynamic performance is hard limited by the motors and I don't see anything new here for some ( many ) years by now. Quite the contrary, some of the fancy stuff has been dumbed down or downright disappeared. 20 years ago it seemed that linear motors will eat up anything else. Guess what ?

[alexo]

Here's an example :

http://www.ebay.com/itm/200W-servo-motor-drive-MSMJ022G1V-MADKT1507E-with-3m-cable-0-64Nm-3000rpm-brake-/201336979447?hash=item2ee09e7ff7:g:~aAAAOSweW5VOlwB

This is a fairly good system I used quite a few times. For common applications I can match it's abilities with a stepper for 1/5 of the price. I then use the leftover monies for proper ballscrews and you WILL see the difference in the quality of your circles. There is NO WAY to sort that out just by using servos as we don't know what and how much you are going to cut one day.

[CM800]

Linear motors never took off as far as they could as they were too expensive due to production methods. The cost is coming down dramatically these days.
They are nearly at the point where cost is equivalent to a well made ballscrew + motor.

You spend a lot of time talking about how you have problems with servos, but you keep talking about units that are so terrible I would clean my browser history after looking at.

Elmo have been manufacturing for a very long time, They have supplied over 3 million servo drives, a good number of them into military applications (anti-missile targeting systems, etc.)

I've seen first hand what you can actually do with a well made drive, and daaamn.

Most of the problems people have with servos really are with the cheap, shitty units like those from china or badly developed units from large manufacturers who's development team has been shrivelled up.

The cost isn't even that bad, especially for how much of an improvement they make to a system (heck, some of the clever uses of filters can be to help dampen vibration from bad mechanical design)

you're looking at around £500-£700 for the drive and £100-£200 for the motor, however that price drops down significantly for volume.

If you are scrapping parts with a servo system, that's a cock-up on your side.

[alexo]

Well, I'll have to move on as it doesn't seem we have similar requirements from servos or steppers. I'm talking factory floor equipment - 200GPB won't buy me the cables between the motor and the drive. In real life, most equipment can't take advantage of the performance of high end servos for too many reasons to mention here. I've no idea where your experience exactly rests but my some 80 or so retrofits taught me I must be very careful before jumping into the latest fad. And linear motors were WAY cheaper than servo+C3 ball screw 20 years ago. It was the horrible cogging and the holding torque issues which switched me off.    Bottom line is that the R&D teams of large machine tool manufacturers are surely cleverer than you and I put together and squared and they still manage to blunder grievously like EIGHTY percent of the time.

[CM800]

Well, I'll have to move on as it doesn't seem we have similar requirements from servos or steppers. I'm talking factory floor equipment - 200GPB won't buy me the cables between the motor and the drive. In real life, most equipment can't take advantage of the performance of high end servos for too many reasons to mention here. I've no idea where your experience exactly rests but my some 80 or so retrofits taught me I must be very careful before jumping into the latest fad. And linear motors were WAY cheaper than servo+C3 ball screw 20 years ago. It was the horrible cogging and the holding torque issues which switched me off.    Bottom line is that the R&D teams of large machine tool manufacturers are surely cleverer than you and I put together and squared and they still manage to blunder grievously like EIGHTY percent of the time.

I'm getting tired of this, but one more reply to your ill-thought out responses.

This is far from a 'latest fad' it's tried and tested units, there are over 3 million axis out there using these drives from this manufacturer alone.

Cogging is not an issue anymore these days, modern drives have anti-cogging calibration that is impressively functional.

I'd strongly suggest you try it before you knock it. Why not contact the Elmo representative in South Africa, they could give you a good rundown of just how much of a benefit these modern servos can add to application.

I only speak so highly of Elmo because I haven't seen a damn servo-drive better then what they have shown off.

You can't claim experience with apples and the ability to judge them simply because you have tried a lot of pares and oranges.


 

[thm_w]

I'm not sure adding $100 to a cheap 3d printer is very cost effective, but I have a skipping Y axis so I want to try a closed loop stepper.

What has been done to try to solve the problem though.
Have you tried: checking motor current, swapping motor drives, motor, checking for binding, etc.?
You might want to create a thread here or somewhere else to further investigate the issue first. Not that I would discourage getting a smart stepper to play with.

[alexo]

Well, I'll have to move on as it doesn't seem we have similar requirements from servos or steppers. I'm talking factory floor equipment - 200GPB won't buy me the cables between the motor and the drive. In real life, most equipment can't take advantage of the performance of high end servos for too many reasons to mention here. I've no idea where your experience exactly rests but my some 80 or so retrofits taught me I must be very careful before jumping into the latest fad. And linear motors were WAY cheaper than servo+C3 ball screw 20 years ago. It was the horrible cogging and the holding torque issues which switched me off.    Bottom line is that the R&D teams of large machine tool manufacturers are surely cleverer than you and I put together and squared and they still manage to blunder grievously like EIGHTY percent of the time.

I'm getting tired of this, but one more reply to your ill-thought out responses.

This is far from a 'latest fad' it's tried and tested units, there are over 3 million axis out there using these drives from this manufacturer alone.

Cogging is not an issue anymore these days, modern drives have anti-cogging calibration that is impressively functional.

I'd strongly suggest you try it before you knock it. Why not contact the Elmo representative in South Africa, they could give you a good rundown of just how much of a benefit these modern servos can add to application.

I only speak so highly of Elmo because I haven't seen a damn servo-drive better then what they have shown off.

You can't claim experience with apples and the ability to judge them simply because you have tried a lot of pares and oranges.


 

Well, it's clear to me now that you haven't seen many drives or actually used any. I looked over their site, couldn't find any documentation and even the installation manuals were password protected. There is practically NO technical information available - it's all vague talk about "performance". The general look of the drives / motors and CONNECTORS ( !) indicates a CHEAP product.
Take a look at the capabilities of a mid range drive like Omron/Mits/Panasonic R88D-KT series and then talk. Notice the 2Khz speed response. Looking over their marketing spiel I see absolutely no extra capability from Elmo drives/motors but I see a HUGE amount of stuff they don't do.

But in order to make you happy I'll get an Elmo drive and motor and test it against a Panasonic R88 drive and post the results here. That way we'll see what's the apples and what's the pears. Please PM me your contact details - if the Elmo loses, I'll send you the Invoice.

[rs20]

To the OP, just to be aware of some vaguely comparable things already in the market:

- Mechaduino
- Teknic Clearpath

And probably many more; above are just listed things that I actually personally have!

[CM800]

Well, I'll have to move on as it doesn't seem we have similar requirements from servos or steppers. I'm talking factory floor equipment - 200GPB won't buy me the cables between the motor and the drive. In real life, most equipment can't take advantage of the performance of high end servos for too many reasons to mention here. I've no idea where your experience exactly rests but my some 80 or so retrofits taught me I must be very careful before jumping into the latest fad. And linear motors were WAY cheaper than servo+C3 ball screw 20 years ago. It was the horrible cogging and the holding torque issues which switched me off.    Bottom line is that the R&D teams of large machine tool manufacturers are surely cleverer than you and I put together and squared and they still manage to blunder grievously like EIGHTY percent of the time.

I'm getting tired of this, but one more reply to your ill-thought out responses.

This is far from a 'latest fad' it's tried and tested units, there are over 3 million axis out there using these drives from this manufacturer alone.

Cogging is not an issue anymore these days, modern drives have anti-cogging calibration that is impressively functional.

I'd strongly suggest you try it before you knock it. Why not contact the Elmo representative in South Africa, they could give you a good rundown of just how much of a benefit these modern servos can add to application.

I only speak so highly of Elmo because I haven't seen a damn servo-drive better then what they have shown off.

You can't claim experience with apples and the ability to judge them simply because you have tried a lot of pares and oranges.


 

Well, it's clear to me now that you haven't seen many drives or actually used any. I looked over their site, couldn't find any documentation and even the installation manuals were password protected. There is practically NO technical information available - it's all vague talk about "performance". The general look of the drives / motors and CONNECTORS ( !) indicates a CHEAP product.
Take a look at the capabilities of a mid range drive like Omron/Mits/Panasonic R88D-KT series and then talk. Notice the 2Khz speed response. Looking over their marketing spiel I see absolutely no extra capability from Elmo drives/motors but I see a HUGE amount of stuff they don't do.

But in order to make you happy I'll get an Elmo drive and motor and test it against a Panasonic R88 drive and post the results here. That way we'll see what's the apples and what's the pears. Please PM me your contact details - if the Elmo loses, I'll send you the Invoice.

Amusing you say I haven't seen many drives or 'actually used any' considering my actual job is configuring, setting up and testing Servo drives. Selecting, installing and providing technical support for servo drives is there about half my job.


Also I'm pretty confused by you saying you see a 'huge' amount of things that the Elmo drives don't do. Mind pointing out some? 

A lot of the information is locked up with an account as it is propriatory information and they like to have some level of control as to who has access to it.

I'm more then happy to share with you some of the specs:

Current closed loop bandwidth exceeding 4kHz
Current / Torque Sampling rate: up to 25kHz
Velocity Sampling rate (up to 10kHz, can be increased to 16.67kHz)
Position Sampling rate (up to 10kHz, can be increased to 16.67kHz)
Electrical commutation frequency: up to 3kHz

S-curve profile smoothing

Cogging compensation

Duel Loop Operation supported by Autotuning

On the fly gain scheduling of current and velocity

Automatic Commutation alignment

Automatic motor phase sequencing

Advanced filtering (low pass, notch, lead/lag, general biquad)

Current loop gain scheduling to compensate for bus voltage variation

Gains and filter scheduling vs. position for mechanical coupling optimization, speed and position tracking errors

Velocity gain scheduling using high order filters.

Output compare repetition rate: 13kHz
Motion modes: PTP, ECAM, Follower, Duel Loop, Current follower
1us latancy on output compare.

Full encoder support (including several propriatory ones (ask and recieve from them)

I think that exceeds anything else you can suggest from other products.

Far from cheap, I've seen inside these drives, they are damn beautifully made, the power stage is on a custom ceramic substrate for some of the higher power ones.

they have developed their own ASIC gate-driver that allows extremely efficient switching

I can't disagree there are some things that sound like 'marketing wank' but I'll be damned it's all true.

Check out this drive, 4kW and only 22 grams...

http://www.elmomc.com/products/gold-twitter-servo-drive.htm

And yes, I called bullshit with them when I first saw it, but they actually show it running at full power on their stand at some exhabitions.


If you were in the UK, I'd be happy to organize sending you one of the servo drives and a motor to test it with, but South Africa doesn't have the best reptuation. Why not ask the local Elmo Sales office there if they could offer a demo kit to play with or something similar?


EDIT:

Here, I've uploaded this just for you:





It's not continuous, but it's the best demo you can do without a significantly large load, even then, it's quite a nice show considering the inertia of that huge motor and the size of the drive.


Another impressive feature I forgot to mention is that you can put drives in parallel for the same motor (you use a special cable between 2 of the output / input ports and use a duel wound motor) that way you can have a seriously small drive form factor. For example, one of the customers uses their HV Drums, 2x 65kW units running a 120kW duel wound motor.

[alexo]

Well, now that I find you work for them things are different. I won't compare with specific products anymore and I was getting ready to do just that. I think you have some idea how much people like me are being pestered by sales people trying to push product. Nothing wrong with that but for the fact they almost never seem to know what the product is used for by me. Most of my interest is 1 to 4Kw metal cutting machine tools. Wood chopping sometimes. That means most of the claimed features of new products are absolutely irrelevant. A CNC machine can work for many hours on an expensive mold and a single error could translate into a large loss. And errors happen all the time because the toolpath software is not foolproof. If you machine a mold for a say a car door then how fast the machine moves while cutting air or between tool changes is irrelevant. Reliability is everything. Dynamic performance is a big issue with lasers where forces and speeds are perfectly well known.

Elmo's idea to call their drives "Clarinet" , "Bassoon", Accordion and so on was stupid. My clients tend to fork out money for Yaskawa or Mitsubishi and at a push might be ok with products from a TV making company. Like Panasonic. This is reality. For me is counterproductive to push product from lesser known manufacturers and it'd take me a page to explain why in detail. One example : check how much 2nd hand stuff from Elmo is available "out there". Now compare with Panasonic or Yaskawa. That matters big time for me and many like me.

I couldn't discover Elmo's sales office in SA but anyhow, I would definitely not have the time to test their products. Nor would I be prepared to put up with the expense. The couple of figures you kindly supplied and some others I was forwarded by somebody in the US do not warrant the trouble. The fact they do not have product manuals freely available and sufficiently detailed is an alarm signal for me. Seen that before once or twice... It's a very bad policy - I'm not going to "discuss my needs" with their almost incompetent sales rep. It'll be a waste of time and I don't want to have my clients shortcircuited.   

The 22g and 4Kw drive is an impressive piece of engineering but what would I need it for The demo you kindly uploaded shows it works somehow. Not knowing what the peak power and duty cycle are there that might as well be a 400W drive. Might be 50W...

Powering one motor from two drives is interesting but again, nothing I could use it for. Never had an issue with the available space for a drive. This is a real niche application and given that a specially wound motor is needed I'd be hard pushed to even start imagining where this could be useful. And anything over 10Kw is completely out of my league.

[CM800]

Well, now that I find you work for them things are different. I won't compare with specific products anymore and I was getting ready to do just that. I think you have some idea how much people like me are being pestered by sales people trying to push product. Nothing wrong with that but for the fact they almost never seem to know what the product is used for by me. Most of my interest is 1 to 4Kw metal cutting machine tools. Wood chopping sometimes. That means most of the claimed features of new products are absolutely irrelevant. A CNC machine can work for many hours on an expensive mold and a single error could translate into a large loss. And errors happen all the time because the toolpath software is not foolproof. If you machine a mold for a say a car door then how fast the machine moves while cutting air or between tool changes is irrelevant. Reliability is everything. Dynamic performance is a big issue with lasers where forces and speeds are perfectly well known.

Elmo's idea to call their drives "Clarinet" , "Bassoon", Accordion and so on was stupid. My clients tend to fork out money for Yaskawa or Mitsubishi and at a push might be ok with products from a TV making company. Like Panasonic. This is reality. For me is counterproductive to push product from lesser known manufacturers and it'd take me a page to explain why in detail. One example : check how much 2nd hand stuff from Elmo is available "out there". Now compare with Panasonic or Yaskawa. That matters big time for me and many like me.

I couldn't discover Elmo's sales office in SA but anyhow, I would definitely not have the time to test their products. Nor would I be prepared to put up with the expense. The couple of figures you kindly supplied and some others I was forwarded by somebody in the US do not warrant the trouble. The fact they do not have product manuals freely available and sufficiently detailed is an alarm signal for me. Seen that before once or twice... It's a very bad policy - I'm not going to "discuss my needs" with their almost incompetent sales rep. It'll be a waste of time and I don't want to have my clients shortcircuited.   

The 22g and 4Kw drive is an impressive piece of engineering but what would I need it for The demo you kindly uploaded shows it works somehow. Not knowing what the peak power and duty cycle are there that might as well be a 400W drive. Might be 50W...

Powering one motor from two drives is interesting but again, nothing I could use it for. Never had an issue with the available space for a drive. This is a real niche application and given that a specially wound motor is needed I'd be hard pushed to even start imagining where this could be useful. And anything over 10Kw is completely out of my league.

Haha, no. I don't work for them...

Frankly they supply a lot to military applications and don't cater to small volume applications like retrofitting due to support requirements. Don't flatter yourself in thinking I'm some kind of salesman targeting you.

I provide technical support and do setup / integration work across 4-5 different servo drive manufacturers.

I'm not trying to sell it here, I think you got me wrong. I admit it sounds like I'm pushing the product a bit, but this entire conversation is more about -servo drives- then anything else. I'm only pointing out Elmo as they are damn impressive in performance and reliability.

For your information, we do see a lot of business in the twitters. They are used often in drones, robot arms and other compact machines.

Again, most of this stuff isn't even targeted at you, because there isn't much business in that area, but it is still useful when other drives simply don't give the performance available.

That said, I do agree they should put more of the information out on the public.

Drones and electric vehicles are a good example for a specially wound motor and need for extreme compactness. You want as much space as possible for extra batteries and want to drop weight a lot too.

If I actually was trying to push this product, I'd be going about it a very different way. Its amusing how hostile you seem to new technology. I take it you still use exclusively analogue scopes and resolvers? 

[Assafl]

There is an entirely underserved market for people with some experience with motor controllers: car parking systems.

In the building next to ours they installed a parking robot. 6 months it stood barren since a turnstile (on the robot) would not stop within the allowed angle. In discussing this with their support team they insisted that cars were "heavy" and therefore the servo was "unable" to position the cars correctly. They insisted the motor/drive pair was good and well specified and configured (yeah right).

They ended up welding a spring (and I assume some form of damping) that the turnstile would stop against.

Crappy systems.   


 

[CM800]

There is an entirely underserved market for people with some experience with motor controllers: car parking systems.

In the building next to ours they installed a parking robot. 6 months it stood barren since a turnstile (on the robot) would not stop within the allowed angle. In discussing this with their support team they insisted that cars were "heavy" and therefore the servo was "unable" to position the cars correctly. They insisted the motor/drive pair was good and well specified and configured (yeah right).

They ended up welding a spring (and I assume some form of damping) that the turnstile would stop against.

Crappy systems.   


 

That is rediculous... Someone can't design a system properly...

Interestingly enough, that was one of the examples the Elmo Sales guy showed us, they were using 2 65kW servos  to run a large motor, it was for going under cars, picking them up and putting them into their parking spots. Battery powered, it goes back to it's place and recharges when finished.