Motion Controller

[akshayc]

Hi

I am using PCI-7332 - UMI-7764 - P70360 Stepper Drive - N31HRLG-LNK-NS-00 Stepper Motor.

The assembly is programmed to move a wheel with 12 optical filters, 30 deg at a time at all filter positions.

My question is  when i switch of the entire assembly the wheel is free to rotate and so it looses its starting position and everytime i have to set it to a particular positon before starting the experiment.

So i am thinking of placing a switch on the wheel at a position so that before starting the experiment everytime (when programmed) the wheel revolves for one full cycle but stops when the switch is pressed. This way i dont have to set it manually to a position everytime. I need to know how can i manage the this thing with the hardware that i have, i am not using an encoder and not planning to have one.

Thanks

AKSHAY CHAVAN

[Nate.H]

Hi Akshay,

The behavior you describe is called a 'reference move' in our documentation, and the switch you propose to add to your setup a 'home switch'. You can configure a home switch from the Motion I/O settings tab in MAX, and the behavior of your reference move from the Find Reference Settings»Home configuration tab in MAX

 

There are also example programs for finding reference settings available for both LabVIEW and C.

Text Based: \National Instruments\NI-Motion\FlexMotion\Examples\C\FindReference

LabVIEW: Use the example finder and search for 'Find Reference' or go to \National Instruments\LabVIEW 2009\examples\motion\FlexMotion 

You should be able to implement a home switch with your existing software and hardware setup without adding an encoder to your system. Please let me know if you have any additional questions when implementing this in your system.

Have a great day!

Best Regards,

~Nate

[akshayc]

Hey thanks

But i am using  D-Sub to Leads Cable for P70530 & P70360 Stepper between UMI 7764 andP70360 Stepper Drive.

It does not have leads for the home switch, so can use any switch and wires to make that work.

so if I am using home switch, so the connection should be on home input and digital ground terminal of which ever axis i am using.

Are there any requirements on the switch (normally closed or normally opened).

Thanks

AKSHAY CHAVAN

[Nate.H]

Hi Akshay,

As long as the switch is wired properly, you can use either a normally closed or a normally open switch, because you can configure the active state from the Motion I/O settings in MAX.

Best Regards,

~Nate

[akshayc]

Hi Nate

The previous problem is solved, but there is another one.

I am moving the motor in staright line motion, but through matlab, made a dll file, anf the input it steps for the matlab function.

Now i am moving the motor thorugh a for loop in matlab. (along with a cam), the for loop executes 10 times with steps as 17-16-17-17-16-17-17-16-17-17;

the motor moves the wheel more than what it should be and so i am not getting the accurate placement of the wheel and by the time it completes the 10th time in the for loop the wheel is way of its required position.

When i tried this with one execution at a time (in Matlab but not through for loop) it works properly. I tried setting a delay after each motion but the problem continues and its only when it is in loop.

Please help

Thanks

AKSHAY CHAVAN

[Nate.H]

Dear Akshay,

Your current problem may have to do with how the DLL functions. Did you build this DLL from LabVIEW? Did you use the NI-Motion C API and a text based language?

In any case, make sure you are accounting for this behavior. If the Motion code in the DLL initializes the motion card, performs a stright-line move, and then ends the move and cleans up references, your encoder position will be reset to zero the next time the DLL initializes and performs the next stright-line move (unless your specifically acocunted for this). Are you setting your desired position in relative terms from where the motor is supposed to end up after the previous move? Does the motor still maintain holding torque between iterations of the FOR loop? These are just a few of the things that could be going wrong, but I can't be sure without looking at code.

The ideal case for this motion would be to initialize the controller once, load all your move parameters, and then step through an array of desired straight-line moves by updating the setpoint. You can find examples of how this kind of continuously updated move is performed through the motion examples. 

Please let me know a little more detail on how your code is architected if the above doesn't give you any leads on solving your issue. 

Best Regards,

~Nate

[Khanh]

Dear all,

Dear all,

I tried to make a program to isolate vibration for a Vibration Isolator.

I already use PID controller (by using PID.VI in Labview).

I got nice experiment.

Now I want to try with other algorrithm (other controller) --> by using Pole-placement technique.

However I could not find out similar controller as PID in Labview Library.

I am a beginer in Labview so I hope all of you help me to solve my problem.

Thank you very much.

Dear all,

I tried to make a program to isolate vibration for a Vibration Isolator.

I already use PID controller (by using PID.VI in Labview).

I got nice experiment.

Now I want to try with other algorrithm (other controller) --> by using Pole-placement technique.

However I could not find out similar controller as PID in Labview Library.

I am a beginer in Labview so I hope all of you help me to solve my problem.

Thank you very much.

Best regard!

Dear all,

I tried to make a program to isolate vibration for a Vibration Isolator.

I already use PID controller (by using PID.VI in Labview).

I got nice experiment.

Now I want to try with other algorrithm (other controller) --> by using Pole-placement technique.

However I could not find out similar controller as PID in Labview Library.

I am a beginer in Labview so I hope all of you help me to solve my problem.

Thank you very much.

[Paul_M.]

Hi Khanh,

This is Paul, one of the applications engineers at National Instruments. The Pole Placement.VI that you're looking for is actually part of the Control Design and Simulation Module that is not included with the standard LabVIEW install like the PID.VI. That being said, you can download this module from our website and use it in evaluation mode for 30 days. To do this, follow this link and follow the module link for your version of LabVIEW and then download the module. Let me know if you have anymore questions.

Paul M