Stepper Motor Feedback sensor

[SK0480]

Iam building a positioning control system using a stepper motor. I need to know few things

1. Are there any simple sensors availble out there to be used for position sensing of stepper motor like LVTD .

2. How do I obtain a transfer function of a stepper motor so that I can convert my stepper motor position control system from S domain to Z-domain.

Thanks

[Kimberly_Wenger_Austin]

Hi SK0480,

First off, do you already have a motion controller and/or drive for your device?  As for a sensor, you could easily use a quadrature encoder to read the feedback from the motor.  Here is a great tutorial on how to take a quadrature encoder measurement.  Once I get a little more information, I will be able to help you further.  Thanks!

Kim W.

[SK0480]

Hi 

Well Iam not doing anyting sophisticated where I will need to use motion controller software..It is just my senior project and Iam building a positioning control system and I need some guidance.. Here are the tools I have 

NI ELVIS Board with data acquisation card

Labview

Now I dont want to use anything expensive like quadrature encoder-Iam looking for some simple sensor that I can use to measure the position of the stepper motor.

Thanks

[SK0480]

Another thing I want to know is how can I link simulink with Labview..

[Kimberly_Wenger_Austin]

Hi SK0480,

First, in order to use Simulink with LabVIEW, you must have the Simulink Interface Toolkit. Here is a tutorial of how to build the user interface with Simulink.

Since you are using a stepper motor, it may not be necessary for you to have an encoder.  You can easily send commands to the motor to move a certain number of steps and it will execute and record how many steps it has gone (based on the input from the user as opposed to from the device), but if you would like feedback from the device to make sure that there were no slips during execution, then you will need an encoder.  As far as the quadrature encoder goes, these are not very expensive (way less than $100) and the pricing would depend on how accurate you wanted it to be.

What type of DAQ device do you have?  Here is a simple example of how you can use DAQmx to control a stepper motor.  Finally, how do you plan to power your motor and interface it with LabVIEW?

Kim W.

[SK0480]

Thanks very much for your reply, this helps a lot. Ok now can I also use a PID to reduce the error for the stepper motor control system. And lets say If iam using a C code to implement a PID, what are some ways I can use C code in the LABVIEW. 

[SK0480]

and all the data that I get in my labview program for the positioning control systems. How  can transfer that data in to matlab for further examination. Like lets say once find all the parameters in the labview like reference value, then is there anyway I can create a link for matlab in the Labview program.

Thanks

[Kimberly_Wenger_Austin]

Hi SK0480,

You can call dll's created in C in LabVIEW through the Call Library Function node.  Here is a tutorial on how to call a dll in LabVIEW.  Also, here is an example of running a C dll in LabVIEW.

As far as Matlab goes, you can easily write all your data to text file or a binary file and incorporate that into your Matlab code for further review.

I hope this helps!

Kim W.

[SK0480]

hi

Can anyone tell me how can i obtain a transfer function for a stepper motor

Thnx

[johnsold]

If you are using ELVIS, you are probably operating the motor in full step mode at relatively low speeds and load torque well below the slip limit for your motor. In that case you do not need PID or a transfer function.  I think you are trying to make this much, much more complicated than it needs to be.

You said this was a senior project. What is the goal of the project (besides graduation)?

Lynn