Controlling linear actuator

[Crispr9]

Hi guys,

I´m new in using LabVIEW but I have to write a programm to control an actuator. I´m getting stuck - so I hope one of you have a tipp for me 🙂

I´m using LabVIEW 2014 (Real-Time and SoftMotion already installed), cRIO 9035 with two modules (9514, 9205), and a linear actuator connected to a servomotor and an amplifier.

I get a force signal from a external actuator - this signal I want to compare with the signal from the servomotor I get and adjust it in a specific ratio.

So in the end I have two force signals to compare and I don´t know how to manage this 😞

[n_dakota]

Hello Crispr9,

Message you wrote is relatively generic and it is hard to understand what issue are you exactly facing. Did you manage to move forward with the project? Is there any specific point where you got blocked (hardware setup, configuration, specific step in software)?

[Crispr9]

Hi n_dakota,

not really...

now I have the problem that I want to compare the two signals if they are equal, greater or smaller... and depending on this I want that the actuator is moving forward if the signal is smaller, moving backward if it´s greater, and keeping the position if it´s equal... but I´m struggling with the execution!

Because right now I have a while-loop where all my signals are going in. There I have the three comparison blocks (equal?, Less?, Greater?) and depending on whats right there are three Case-structures one for each. For the greater? --> case true -> stop move -> straight line move (with positive velocity), and so on. But is there a more elegant way or even simpler? Thank you in advance!

Best Regards,

GP

[n_dakota]

Hi GP,

First simplification would be to eliminate the comparison blocks and connect numeric input directly to case structure. You can define in case name if it will work with number lower, equal or greater to numbers you set.

Hope it helps!

[QMESAR]

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@Crispr9 wrote:

 I have the problem that I want to compare the two signals if they are equal, greater or smaller... and depending on this I want that the actuator is moving forward if the signal is smaller, moving backward if it´s greater, and keeping the position if it´s equal...

Hi ,

I am probably newer than you to labVIEW so please take my comments with some care .

However, I take it the one signal is your "Setpoint" or reference to where you need the actuator to move too,the second signal is the position feedback from the actuator signalling it's actual(at this moment) position .

with this in mind this is a  PID Control System depending on your system dynamics etc.it could be only PI Control.In fact it does not matter in what units the signal are Force ,Pressure speed etc it about the Error between the reference (the property that you need ) and the actual property and for example if the error is negative then your actuator is to far and if it is positive it lags the needed position .all you need are done by the character of PID Controls. 

I would think that the labVIEW Control Design Module  can be of great help to you ,or it might be possible to implement a PID in labVIEW directly this is probably for the guru's around to tell