acutator control

[cees10]

Hi i am new user to labview.

I have a question about  to control a acutator  position

I have a pot meter that i read out between 0-10 volts on 6008 ,then i control a digital out put on port 0 bit  4 (for down) bit 6 (for up)

I want to set a certain value let say 8.6 volts on pot meter and the motor have to go up or down to reach the value that it put manual in

I can control it now (as i seen a example file with labview)    but i really have no idea how to let the motor go up or down automaticly to desired value and then stop

Any one who could help me?

thanks in advance 

[JÞB]

Sure!

I can help explain what you see.  Of course, I'll need to see it too!

Can you post the code in question?

[cees10]

well that fast thanks jeff

remember i do not have a input field yet!

For the value of the  wished value of pot meter 

[cees10]

well here a version

with slider and controls from the channels

how can i make it go to the slider value? 

[Henrik_Volkers]

You want to build up a controller.

Fist step: read the pot and get the offset by subtracting it from the setpoint. 

Simple 2 point controller: depending on the offset move the motor up and down. Disadvantage: The motor will tend to never perfectly hit the setpoint and will always move up and down.

Simple solution: Include a dead band (Don't move if the absolute value of the offset is within a defined range), however you have to live with that dead band error.

Your motor will need some time to accelerate and will probably not stop right after being powered off.  More sophisticated controller take that into account.

Also there might be a some hysteresis in the mechanics, the motor might need a minimum turn on time or startup power due to friction.... 

Next point: Your acquisition will always be behind reality (1µs ...100 ms)...

More sophisticated : Use PWM to control the  motor speed ....

[Henrik_Volkers]

Here is a 10 min quick try (right after lunch 😉 

I don't have a DAQ here, so don't expect to have it run the first time 😉

Base was an example that i modified, however I don't know if the DAQ is setup correctly

Message Edited by Henrik Volkers on 11-11-2009 01:45 PM

[cees10]

Well henrik  i tried 

well i am missing a file it seems at least like that

get terminal name with device prefix .vi

And pwm is no option since i cannot control it with a  6008    and since it for out door use with small battery and laptop and price for other setup is too big i really have to go this way

i Think  i have to live with the band error 

cees 

[voogt]

get terminal name with device prefix .vi

I need this file

No where on my harddisk i can find this file ,altough i have read i should be in a example file  but the named example file is also not on my harddisk

Our local support guy at national instruments does not give any answer ,it not his problem he says i have no idea where you can find this file

Is there any location on the web site where i can dowload the example file's?

Cees 

[aeastet]

I can not promise that I fixed it but here is a working copy.

[cees10]

could you downgrade it to version 8.6 please?