Creating a Positioning system for controlling the linear movement of a dynamometer

[SS23]

Hey everyone, I am a new user of LabView attempting to create a positioning system for a linearly moving dynamometer. (on rails)

The idea is to control the machine's movement through LabView by directing the motor to move or stop. I have found the solution to this by using a Frequency Converter Teco CV7300 to control the 0,55 kW induction motor.

The machine whose position is to be controlled is mounted on a movable base with air brakes and a leadscrew with gearbox. Finally, the gearbox has a shaft where the motor would be mounted.

My task is to integrate Air brakes release/engage (using Solenoid valve) mechanism, motor start/stop(using frequency converter), machine's position detection (using potentiometer) all using a single LabView program.

The main issue is about the compatibility of the parts and how they would interact with DAQ. NI cDaq-9174

Given its enormity, I am struggling to know how to proceed with the integration. As of now, I have short listed all the exact parts and have a final idea how things should work.

But not knowing the inter-connection in LabView, I need some reference on how to start creating the LabView program.

Parts:

1. Solenoid valve : 24 VDC  (For controlling flow of air into brakes of machine to release/engage brakes)
2. Draw wire sensor : Potentiometer (max 32VDC output supply) Machine's position measurement
3. 3-Phase 0,5 kW AC motor with Teco CV7300 Frequency converter (Motor start/stop, fwd/reverse control).
4. Limit switch : To limit machine's movement at ends of linear rails.

Any help in this regard would be highly appreciated.
Looking forward to some community help! Thanks!

[Bob_Schor]

If you wish to do this yourself, you will need to not only "learn" LabVIEW, but become sufficiently familiar with it that you can design control systems using LabVIEW.  Do you have a background in Systems Theory?  Do you understand the principles of digital control?  Have you reached sufficient experience with LabVIEW to pass the CLD exam?

You may benefit from finding a good LabVIEW Developer and "apprenticing" yourself to her/him for several months.

Bob Schor

[SS23]

Hi Bob,

Thanks for your reply and my apologies for the absence. I have been trying since then to simplify the system for myself and everyone else to understand.

My progress so far:

1. Solenoid Valve connections understood

2. Draw-wire sensor connections understood

3. Found out about RS-232 connection option for VFD.

But, I still have some key issues with my system.

1. How to virtually implement the controlling of Frequency converter in Labview with all controls for the motor(start/stop/fwd/rev)?

2. Integrate the limit switch in the Labview program to cut-off the frequency converter if the limit is reached in movement.

Once, I get these issues sorted I can start to assemble my system into a single piece.

Thanks in advance! And a Happy New Year soon!

[Bob_Schor]

Put LabVIEW away for a moment, and break out your favorite Word Processor.  You want to write some documentation that describes the following:

• Hardware:
  • Motor Controller that uses Serial communication and has four basic commands, Start, Stop, Forward, Reverse.
  • Solenoid Valve that uses a digital signal (On/Off).
  • Analog Input to read Position Potentiometer.
  • Digital Input to read Limit Switch.
• Logic of What you want to do, where possible broken up into individual "Actions" or "States" (this leads to the creation of a State Machine).
  • Example:  Initialize Hardware, Read Control Parameters, Start Movement, Check Limit Switch, Reverse Movement, Stop Movement.
  • Recommend creating Enum holding the various "States"/"Actions".
  • Describe what causes a State Transition.  Many actions are in response to something like a Button Press, others might be timed ("Every 100 msec"), some might be Sequential ("Set These Controls, then Do Something Else").
• There are several State Machine Templates available (JKI State Machine, LabVIEW Tools Network; Simple State Machine, built-in LabVIEW Template; Queued Message Handler, built-in LabVIEW Template, though some dislike calling this a State Machine ...).

Once you have some idea of what you want to do, you can start figuring out how to do it using LabVIEW.  The QMH, I believe, shows how you can integrate an Event Loop that responds nicely to Button Pushes into a "Do This when I push That Button" situation.  But do get as much of the Broad Outline (the "What") down on paper first -- it may seem silly, but "Write the Documentation First!" has been possibly the most ignored piece of Good Advice from Software Experts for the past 30-40 years ...

Bob (who tries to follow his own advice) Schor

[SS23]

Hi Bob,

Thanks for keeping this thread alive. Firstly, a Happy New Year!

I took your advice and tried to create an outline of my requirements and specs for the parts used. Please have a look on my system overview and a very basic Hardware logic that I made based on the understanding of your previous suggestions.

I am still trying to understand the various states and actions as you talked about but being a newbie it's kind of tough to gather how to approach the creation.

Nevertheless, if you could guide a bit more in my approach or suggest simplifying the system, I shall be highly thankful to you!

I look forward to your comments! 🙂