Putting robotics at your service™

Free shipping on orders over $200

dc motor

Print view Share :
Previous topicNext topic

Page 1 of 1 [ 7 posts ]

Rookie ( offline )
Posts: 30
Posted: 2009-05-18 10:48 
 Post subject: dc motor
hi everybody
Is there anyone here to work with planetary dc gear motor?
According to my project that is about industrial robot. I need a motor with more accuracy in comparison with servo motor because I need to change the angular position with less than 1 degree. I also need to control the velocity and acceleration that I couldn't control them by servo motor (If I am wrong please help me), so I decide to by planetary dc gear motor.
I have some question about it;
I am familiar with servo motor and I worked with servo controller SSC-32.
Actually I don't know what is the main deference between motor controller and servo controller and I also don't know how can program the motor by motor controller. Is it easy or not in comparison between servo.

I have some more questions and I will ask later.
Thanks in advance
edris


User avatar
Guru ( offline )
Posts: 4127
Posted: 2009-05-18 13:44 
 Post subject: Re: dc motor
The "planetary" part doesn't matter. What you are looking for is a geared DC servo motor with a shaft encoder. You'll need to drive the motor with a PID-controlled amp (driver). There are packaged servo drivers available.

http://www.jrkerr.com/

Is an example of just such a servo controller. You can even buy one of his servo control chips. You'll also need to add an amp, like an LMD18245.

http://www.fromorbit.com/content/lmd18245-arrive-digi-key

The SSC-32 is intended for R/C servo motors (all that stuff is actually inside the R/C servo package).

Alan KM6VV

edsafavi wrote:
hi everybody
Is there anyone here to work with planetary dc gear motor?
According to my project that is about industrial robot. I need a motor with more accuracy in comparison with servo motor because I need to change the angular position with less than 1 degree. I also need to control the velocity and acceleration that I couldn't control them by servo motor (If I am wrong please help me), so I decide to by planetary dc gear motor.
I have some question about it;
I am familiar with servo motor and I worked with servo controller SSC-32.
Actually I don't know what is the main deference between motor controller and servo controller and I also don't know how can program the motor by motor controller. Is it easy or not in comparison between servo.

I have some more questions and I will ask later.
Thanks in advance
edris

_________________
Visit:
http://groups.yahoo.com/group/SherlineCNC/
http://tech.groups.yahoo.com/group/HexapodRobotIK/


Rookie ( offline )
Posts: 30
Posted: 2009-05-28 07:57 
 Post subject: Re: dc motor
what are the differences between the Dc motor that is used in RC servos and the motors below?
http://www.lynxmotion.com/Product.aspx? ... egoryID=11

or

http://www.lynxmotion.com/Product.aspx? ... egoryID=71

I don't know exactly which kind of Dc motor is used in RC servos?


Guru ( offline )
Posts: 2158
Posted: 2009-05-28 12:43 
 Post subject: Re: dc motor
edsafavi wrote:
I don't know exactly which kind of Dc motor is used in RC servos?

<cynical=on>usually the cheapest DC motor a manufacturer can get away with and not have crappy product reviews or significant amounts of product return due to failures.</cynical>

the two motors you link are physically much larger than a motor you would find in a servo, operate at 12V rather than 6V, and are just a motor and gearhead. It requires an external DC motor controller and an absolute position feedback device to create a servo-mechanism.

An r/c servo has a motor, a gear reduction, and a pot for position feedback, and electronics to control the motor from a simple low frequency PWM signal.


User avatar
Guru ( offline )
Posts: 9256
Posted: 2009-05-28 13:20 
 Post subject: Re: dc motor
The better servos use a coreless motor. Our gear head motors are just 5 pole (I think) permanent magnet motors. Perhaps the great all-knowing wiki has information on coreless and / or PM DC motors. ;)

_________________
Jim Frye, the Robot Guy
http://www.lynxmotion.com
I've always tried to do my best...


Rookie ( offline )
Posts: 30
Posted: 2009-05-28 14:55 
 Post subject: Re: dc motor
I am so thankful for your useful information.

I want to control the position , velocity and acceleration. according to your information ,i get for more accuracy i need a geared dc motor with a better motor controller and a feedback device like encoder.

1-Do these devices let me to have position,velocity and acceleration control?
2-Do these devices make a big difference in accuracy in comparison with servo?

if the answer of my 1st and 2nd questions are no please tell me where i am wrong and if are yes please send me the exact right link for purchasing below devices.

best small size geared DC motor
motor controller
feed back device

thanks


Guru ( offline )
Posts: 2158
Posted: 2009-05-28 15:18 
 Post subject: Re: dc motor
edsafavi wrote:
if the answer of my 1st and 2nd questions are no please tell me where i am wrong and if are yes please send me the exact right link for purchasing below devices.

asking for general information and even some assitance is fine and I am obviously willing to help with your understanding, however "send me the exact right link" is a bit over the line for my participation.

find some parts, think about why they may or may not be suitable, and the ones you think will work post the exact right link to here and some folks will probably take look over the info and give you some feedback.

http://www.google.com. :?


 

All times are UTC - 5 hours [ DST ]. It is currently 2014-12-18 09:26
Feedback Form
Feedback Form