Go Down

Topic: Servo motors (Read 1 time) previous topic - next topic

aerosam

Hi

Here is a total newbie question.
I am getting totally confused with the jargon surrounding motors.
1)The RC servo community seems to refer to servos as devices that can maintain a particular angle, but not capable of continuous rotation.
But i believe servos such as
http://www.beckhoff.com/english.asp?drive_technology/default.htm, are capable of continuous rotation. So what is a servo??
2)If i want to maintain very precise rpm control(make rpm change as i wish for example like a sine wave), would i use a servo or a DC motor?
3)If i want to maintain a precise angle and change the angle as i desire, would i use a servo?
4)What is the difference between a motor drive and a motor controller?
5)Can i convert a DC/AC motor to a servo using feedback control with pwm signals generated by the Arduino and a suitable motor controller and encoder.
3)Can i control the above Beckhoff servo using an Arduino? Do i need to buy the Drive from them?

Sorry for all the basic questions, but i can't seem to find an answer anywhere. The sales-reps just confuse me with more terminology.

Thanks
Sam

aerosam

Thanks, that clears up quite a few issues.

This is what i want to do
1)Build a disk whose rpm varies smoothly(like a sine-wave). It could be shifted by a DC value if the motor can't rotate in the reverse direction.
2)Place the Ardu-imu on this disk and log the rotation angle as measured by the encoder and as measured by the imu.

This way i will know how accurate the Ardu-imu is.
I don't need high rpm's.
60 would probably be the peak rpm.
To do this should i buy a "servo" motor like Beckhoff or a plain vanilla DC motor and try to control it's speed using pwm's from the Arduino and a motor controller?

Regds
Sam

AWOL

#2
Mar 31, 2011, 09:49 pm Last Edit: Mar 31, 2011, 09:55 pm by AWOL Reason: 1
Quote
60 would probably be the peak rpm

If you could go as low as 45, an old-fashioned record deck could be a cheap alternative.
(A really old one could do 33, 45 and 78!)
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

aerosam

Hi

@KE7GKP
Why do you say, that the test system has lower reliability than the Ardu-IMU?
Shouldn't the accuracy of the test system be determined by the least count of the encoder?
I want to also modify some of the code on the IMU and check the results, to see if it gives a more accurate result.
Won't a stepper motor have backlash error?

@AWOL
Unfortunately i threw away my record player about 3 yrs ago. So how do i achieve such low rpm's

Thanks
Sam

aerosam

Quote

Your description of the test method seems open-loop. There was no explanation of how to correlate the Ardu-IMU data with the turntable position / speed / orientation.  For that matter, how do you even know the instantaneous information about the turntable?  And how do you get the data from a spinning Ardu-IMU?


Sorry for not being clearer.
I have an Xbee shield that will sit on the Ardu-imu on the rotating disk, that will act as the transmitter.
Another Arduino will sit on the ground with an Xbee shield(reciever) and a Datalogger shield.
This stationary Arduino will log the encoder signal and the Ardu-imu data with time-stamps. This way i will have correlation between rpm of the rotating disk and the imu data.
Therefore as long as my encoder is accurate, i can treat it as a benchmark to evaluate the imu.

Thanks
Sam

Valalvax

Just a minor correction: A motor drive is a electronic system that controls the speed and direction of a motor (as well as numerous other things)

I assume that a motor controller is the exact same thing, just a different term for it.

Go Up
 


Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

Arduino
via Egeo 16
Torino, 10131
Italy