position control

hi i need some web sites that can show the subject of position control of ac & dc motors accuracy or free books that i can download thanks alot

Google for servo motors or shaft encoders - servo motors may have position feedback and or speed feedback. Shaft encoded motors - sounds like what you want . . . have absolute position feedback/

Absolute position means just that - some digitally encoded signal tells you the position of the motor shaft at any angle within some specified resolution.

Stepper motors usually require a "home" position to initialize them on power up - go to a position, close a switch (interrupt a beam of light etc), then it knows where it starts from and can count to a position (easily the most common type of position encoding used today) If something physically interferes with their position they merrily go on not knowing where they are.

And - do you really want to know the position of the motor or what the motor is driving? Do you need uninterrupted 360 rotation of the driven device?

AC servos are practically extinct unless you are talking very large industrial motors with feedback on the driven mechanism (or consider a stepper motor an AC motor) Back in WWII they used them Look up synchros, selsyns, and servos.

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Hewants us to answer his homework for him.

Good Luck! Rich

I have been graduated from faculty of engineering i want to know difference between position control of ac $ dc motors to decide which is better. my motor is suppoosed to be used in a machine for examining diffrent luminares by measuring luminous intensity if you can help plz help thank you

What sort of power / torque / speed? Sounds more like a stepper motor function.

"I have been graduated from faculty of engineering"

Scary ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | |

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

so who will design the new stuff?

martin

I don't know. I'm considering retiring to a life of debauchery ;-)

...Jim Thompson

--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
|  Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
|  Phoenix, Arizona            Voice:(480)460-2350  |             |
|  E-mail Address at Website     Fax:(480)460-2142  |  Brass Rat  |
|       http://www.analog-innovations.com           |    1962     |
             
I love to cook with wine.      Sometimes I even put it in the food.

You'd prefer he write in his native language (Arabic, I'd guess)?

Try googling on "AC servomotor" and "DC servomotor".

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

It would help if you expressed your application a little better

". . .examining different luminares" (light source or reflector/diffuser, or combination etc.?) By measuring luminous intensity. Where does a motor come in to this? Mechanically chop the light source(s), direct the light from two sources into a photometer? Physically move the sources or detector?

The application will tell more about what to use than really general questions about servos. There's different conditions to consider - do you care about speed? How many different positions? How fast and how many degrees of accuracy do you need? Good chance the mechanical design will also come into this.

If you've been "graduated from faculty of engineering," was that electrical engineering? In what country? They don't cover this?

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Highly recommended!

Since so many US employees have been replaced by shaved monkeys (customer support, retail sales) why not continue the trend?