Need DIY controller to run AC servo without encoder

[Zzapp]

Hello to Everyone!

Total newb here and I'm not even sure what type of motor this is.

Actuator full view:
http://www.cnczone.com/forums/attach...d=362568&stc=1


Encoder.
http://www.cnczone.com/forums/attach...d=362570&stc=1


Motor:
http://www.cnczone.com/forums/attach...d=362566&stc=1


The actuator model is IS-MXM-10-100-200 and documentation from intelligentactuator.com. is not for the exact same model.
Link to operating manual: https://www.iai-robot.co.jp/data_dl/...E3708-13B).pdf

Anyway, it says "The actuator is driven by the AC servo control method" (page 20) so I only assume that this is AC servo. On page 63 the cable diagram is for 4 wires. Mine has 3 wires red, white, and black.

Question 1: What do the signals U, V, and W stand for?


I checked the motor with ohmmeter it shows 0.7 ohms for any pair.

Applying 3 volts DC it rotates for just a tiny fraction each time power is applied to any 2 terminals. To rotate the motor in one direction I found I have to switch pairs as shown in this table.
http://www.cnczone.com/forums/attach...d=362578&stc=1


I want to make the motor run first without worrying about the encoder which is for later.

Question 2: With some modification can I use stepper motor controller to run AC servo motor?


I assume the motor has 100 watts (Operating Manual page 13).

Question 3: What is the correct voltage for this motor?


As this is a home project I'm not willing spend a fortune on commercial controls. I would highly appreciate any help to find a DIY controller. Thank you.

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[awerby]

The driver/controller and cable set to run your AC servo is likely to cost more than your actuator did. These motors aren't generic; each one has its own control scheme. You're probably better off cost-wise in removing the motor and installing a brushed DC servo, or a stepper you can easily drive with a standard driver. But just for fun, you can contact intelligentactuator and ask them what they'd charge for their system.

[691175002]

The simplest solution is to swap the motor for a stepper.

You can run the servo with a suitable drive but it will be a PITA. You can get a used Parker VIX (Series AH/AE/IE/IH) off ebay for maybe $50 but configuring and wiring it to run a third party motor is not trivial. For example: Testing the Aerotech ATS125 | Everything Bends

The encoder is required to commutate the motor properly, so you cannot run them independently.

[unterhaus]

I'm really surprised you figured out to commutate the motor by yourself. Do you have the encoder pinout? I assume it has hall tracks

You could get started with the open source radio control brushless motor drives (called an ESC). RC brushless motors are driven open loop. Voltage isn't that important, but you don't want to over-current the motor, that's what makes the smoke come out. Open loop is also called "sensorless" Texas Instruments has a lot of app notes about motor control. That's a real rabbit hole though. I have driven a brushless motor open loop in the past. Startup is the tricky part.

[Zzapp]

Sorry for the late reply I had been googling a lot on the subject and conclusion is that you are both right about using stepper instead.

Not only are there tons of documentation on steppers (information overload!! ) but they are a lot simpler and parts are easy to get hold of.

Thanks for sharing your wise opinion you save me from a lot of trouble.

[Zzapp]

Do you have the encoder pinout? I assume it has hall tracks

Sorry I dont have. This thing is salvaged from a nearby factory and there's very limited documentation from online sources.

I don't think it's using hall sensors though I'm not really sure. I mean based on it having an encoder disk my best guess is that the 2 white components on the disk are optical sensors.

The disk itself is an amazing piece of work with very, very tiny slits and was probably used for accurate work in the factory. Here are some photos to compare the slits to a threaded needle:

http://www.cnczone.com/forums/attach...d=363550&stc=1

My lens has very thin depth of field so I took 2 close up shots:

http://www.cnczone.com/forums/attach...d=363552&stc=1

http://www.cnczone.com/forums/attach...d=363554&stc=1


Thanks for the link to Open-BLDC project I would very mush consider to use it in future project.

[unterhaus]

it probably has hall sensors. They are very cheap. Some encoders have a separate set of tracks that simulate Hall sensors, but it doesn't appear that yours does. Steppers are definitely easier.