servo motors
servo motors
(OP)
Sorry if this sounds silly, but how does a servo motor actually work? I've seen them used in hundreds of applications but I don't know how they actually work. Again, sorry if it is a dumb question.
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RE: servo motors
RE: servo motors
The feedback on a servo motor is usally a encoder or resolver which is attached to the back of the motor rotor and produces a number of pulses or sine waves per revolution of the motor. You then command the controller to rotate the motor x pulses, which it does then holds that position until told otherwise. The type of voltage waveform mostly used is a constant amplitude square wave that is modulated by the pulse width(PWM). The algorithm (formula) used by the contoller has 3 basic factors. Proportional Gain which causes increases power in proportion to the position error, Integral Gain which increases over time and Derivative Gain which acts as a damper.
Servo motors are very high preformance motors with a built in feedback device.
If you go to different servo mfg websites they will usally have more detailed info. Some of the mfgs are Baldor, Allen Bradley, Yaskawa, Sanyo-Denki, Baumuller, Kollmorgen and pacsi.
Hope this helps
Barry
RE: servo motors
http://www.ctc-control.com/customer/elea...
for servo basics
RE: servo motors
http://www.ctc-control.com/customer/elea...
for PID and Servo
RE: servo motors
http://www.packagingdigest.com/articles/...
http://209.41.165.153/stepper/Tutorials/...
(for servo systems)
http://www.uoguelph.ca/~antoon/hobby/ser...
http://www.manufacturingcenter.com/dfx/a...
http://www.microcore.dk/index.php?page=w...
http://www-csl.cs.colorado.edu/LegoRobot...
http://www.icspat.com/papers/460mfi.pdf
(for Robust Optimal Servo Controller)
etc. for more info
RE: servo motors
http://www.ctc-control.com/customer/elea...
for servo basics
http://www.ctc-control.com/customer/elea...
for PID and Servo
http://www.packagingdigest.com/articles/...
http://209.41.165.153/stepper/Tutorials/...
(for servo systems)
http://www.uoguelph.ca/~antoon/hobby/ser...
http://www.manufacturingcenter.com/dfx/a...
http://www.microcore.dk/index.php?page=w...
http://www-csl.cs.colorado.edu/LegoRobot...
http://www.icspat.com/papers/460mfi.pdf
(for Robust Optimal Servo Controller)
etc. for more info
Servo hardware is available over
http://www.thomasregister.com
and type Servo Systems under Product or Service, which will return 139 companies to approach to
Alternately,
type Motors: Servo that will return 232 companies to approach to
and
type Drives: Servo that will return 146 companies to approach to
RE: servo motors
RE: servo motors
Is it a brushed servo, if so make sure power polarity is correct. Also check polarity of +/-10 position command signal if applicable.
RE: servo motors
RE: servo motors
That the motor is compatable with the drive. Unless the feedback is clocked the way the drive expects it to be it won't work.
If this is an old DC servo with a tach it need to be the right polarity also.
Barry
RE: servo motors
Furhter details, a brushless drive, resolver.
As I said, I found a command in the controller for direction (MD), then slept on it last night and went in this morning, looked again at the application code and jumping out at me was XR=0 -- Resolver direction ! changed this and hey presto!
Tried the drive and it ran 1/4 speed, spent all day messing with tweeks to the application before working out new resolver is 14-bit, the old one was 12-bit !
Changed resolver settings in initialisation routine and it runs like a dream!