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### Author Topic: DC Motor Parameters  (Read 7343 times)

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#### LoboBranco

• Beginner
• Posts: 5
##### DC Motor Parameters
« on: May 31, 2010, 04:33:05 PM »
Hello.
I must design a PID Controller for my DC Motor, i know how to model a DC motor, but how can i get the DC motor parameters,like find La,Ra,Ea etc?
I heard something about DC Motor identification,that i have to input a Step(A DC Volgate) and take its output(like velocity,using a tacometer).So if this is right, what am i have to do after this?

#### LoboBranco

• Beginner
• Posts: 5
##### Re: DC Motor Parameters
« Reply #1 on: June 03, 2010, 10:34:24 AM »
I still waiting for some help =)
Thanks

#### waltr

• Supreme Robot
• Posts: 1,943
##### Re: DC Motor Parameters
« Reply #2 on: June 03, 2010, 09:09:51 PM »
We'd help if we know what you are talking about. Could you explain what you need clearer?
Maybe with what you have already and some other examples.

#### w_bwr

• Jr. Member
• Posts: 18
##### Re: DC Motor Parameters
« Reply #3 on: June 04, 2010, 10:47:17 AM »

#### LoboBranco

• Beginner
• Posts: 5
##### Re: DC Motor Parameters
« Reply #4 on: June 10, 2010, 11:21:05 PM »
waltr i really do not know how i can speak clearer than i did =/
What i wanna know is,how can i get the parameters of a DC motor,like here http://www.engin.umich.edu/group/ctm/examples/motor/PID2.html
If you look there,there are some parameters like J,b,K,R etc.
Again...i must get this parameters to do a model of my DC motor to design a PID Controller.
Thanks guys,i still waiting if there are somebody that may help me.

#### waltr

• Supreme Robot
• Posts: 1,943
##### Re: DC Motor Parameters
« Reply #5 on: June 11, 2010, 08:27:54 AM »
Quote
DC motor parameters,like find La,Ra,Ea etc?

I still don't see these variables in the link and still have no idea what they really represent.

Quote
If you look there,there are some parameters like J,b,K,R etc.

These I do see and they are explained in the (refer to the Modeling page for the details of getting these commands) just above where the parameters in the link you posted.

The transfer equations and a motor model is ok to get an idea of how the control system should respond but the model is difficult to produce. It does require real measurements of the real parts.

Here is some info on how to measure motor parameters that may be helpful:
http://www.micromo.com/n390432/n.html

When setting up a PID loop the coefficients are guessed at with a first calculation then the system is run and the response is measured. The measurements are then used to correct the 'model' and new coefficients are calculated.
OR, the coefficients are adjusted empirically until the system responses as desired.

#### Soeren

• Supreme Robot
• Posts: 4,672
##### Re: DC Motor Parameters
« Reply #6 on: June 11, 2010, 04:03:30 PM »
Hi,

Quote
DC motor parameters,like find La,Ra,Ea etc?
I still don't see these variables in the link and still have no idea what they really represent.
Assuming that the lower case "a" is representing the motor at hand, it would be the inductance, the resistance and the voltage drop of the motor respectively.
The OP should have known that if he had paid attention in class.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Engineering is based on numbers - not adjectives

#### LoboBranco

• Beginner
• Posts: 5
##### Re: DC Motor Parameters
« Reply #7 on: June 11, 2010, 11:51:08 PM »
Soeren got what i meant,it's exactly my point,sorry for i did not explain
waltr ,This is what i talking about,it's about to get these parameters doing some measurements,not about modeling,i know how to model,the problem is "After the modeling,how can i got these parameters in numerical form,you know?
I must know what i have to do to take these parameters,without using Identification tecniques.
Sorry for my english
And thanks for the help the link that you sent me might help to find some of these parameters =)