AC brushless servo motor with absolute encoder

[Yahoo1]

Does anybody know which manufacture has product which is AC brushless servo motor with absolute encoder. And usuaully how much more expensive is it compared with an AC motor with resolver or incremental encoder?

Thanks.

 

[jbartos]

Suggestion: Visit

http://www.thomasregister.com

and type Motors: Brushless Servo under Product or Service, which will return 55 companies to approach to

 

[blacksea]

Absolute encoders aren't supplied with AC brushless motors as a rule. Pls pay attention that resolver is absolute position sensor also with resolution up to 16 bit.
The price of absolute encoder is 5...10 times higher than standard incremental encoder with resolution up to 2000 CPR.

best regards,
leonid_gannel@hotmail.com

 

[byrddog]

Try Linde Corp headqtrs in Munich Germany, BYRDDOG

 

[avigodner]

what makes difference between absolute and incremental encoder is a need for initialization (phase search) for incremental one at power-up. More details can be found, for example, at

http://www.drbrushless.com

 

[EdDanzer]

Hi Yahoo1,
Is this question related to the machine that had the gear box problem?
One problem with absolute encoders is interfacing them with a control. The control you choose must be able to accept absolute encoders. With only limited experience, the only advantage to absolute encoders is that you don’t have to home the axis on start up. I have seen no evidence that greater accuracy can be obtained by feed back type, the mechanical constraints of the system seem to have a greater effect over time.

 

[Yahoo1]

Hi EdDanzer,

Actually, this is same machine related to the gear box problem, but not same issue.
Because the machine need to hold the pressure in pump and knows the position when the system loss power. So it is impossible to home the axis on start up. Now I have a solution to do it. But it is a better way if an absolute encoder is possible technically and economicaly.

The machanical problem in the gear box has been solved. Now the machine works fine.

Thank you everyone for the help you gave to me.

 

[SERVOCAM]

As said, it is not very common to have absolute encoders used. I would say 99.9% that I have ever worked on did not require absolute encoders. We normally do not use them, but can. It is that most systems can't accept the signal. We have a SSI Net interface to pull them in.

Is the system power loss due to E-Stop condidtion or bad power?

Most servo systems have the ability to keep control power alive while you dump the bus for the motor. This will keep the encoders live so when the system comes back on-line, you will still have position.

On this comment: "resolver is absolute position sensor" - true, but not multi-turn absolute. Absolute in 1 rev. I don't think there are multi-turn resolvers.



Cameron Anderson - Sales & Applications Engineer
Aerotech, Inc. -

http://www.aerotech.com

"Dedicated to the Science of Motion"

 

[EdDanzer]

You might consider an absolute linear scale. I think Newall make one as well as others. The distance of travel will have an effect on cost. Have you checked with the control people about accepting absolute feedback?
I have use Galil motion control products and there are optional features required to use absolute feedback.
Fagor CNC controls will not accept any absolute feedback.
Servocam, there are multi turn resolvers, just not commonly used.

 

[jbartos]

Suggestion: Encoders tend to have a good coverage on WEB. Visit

http://www.sick.de/de/products/categories/industrial/encoder/en.html

for:
Compared to incremental encoders, absolute encoders have one decisive advantage - they do not need a initialising reference -run.

http://www.encoder-interface.com/

for:
Inexpensive absolute encoders

etc. for more info