Motion Control and Manual Control

[Kenzi]

Hi,

 i am new to Motion Control and my task is to control the motion of Variable Inlet Guide Vanes in a Compressor Test Rig. My Test Rig contains Vanes which are extremely Expensive(ca.10000€). I would like to control my Vanes with a NI NEMA 23 Stepper Motor, NI P70530 Drive, NI PXI 7332 und Labview2009. The problem is that i cant risk that the Computer may run down due to any Electrical Problems for example. I must be able to move my Vanes at any point of time . To give a better picture:for example i am moving my Vanes with Labview and suddenly my compressor experiences a Rotating Stall which will damage my expensive Vanes if i dont move the vanes immediately from that position.But unfortunately at the same time my Computer shuts down for any reason!!i need to have a system which will enable me to manually control my motor as PLAN B.

Is it possible to install a Knob which manually moves my Motor incase i have problems with my Labview Motion Control? can anyone provide me with some Info?ihope my question is clear.

thanks

[Jochen · Accepted solution]

Kenzi,

there is not a trivial answer to your question and a solution could be become fairly complex, depending on how much safety you need  / want to add to your system.

Besides the possibility, that the computer could crash, there could be also a failure in the P70530 drive or in the power supply to the drive or even the motor may fail. So if you need to add redundancy for all these components, you might end up with a completely redundant system (including the power supplies) and some way to switch between these components on the fly.

As this 100% approach is very costly let's assume you only want to cover PC crashes and not drive failures. For such a scenario the easiest solution is to use the user configurable I/Os on the P70530. By default the digital inputs at J4-14 and J4-15 are assigned to jog the motor in positive and negative direction. Thus you can connect buttons to these inputs to move the axis manually.

Please refer to the P70530 user manual for further information.

You need to use the P7000 tools to configure the jog parameters (velocity and acceleration) and you could also change the I/O assignment if required.

If you need a higher level of safety, there are several more approaches, but with your current hardware setup the described solution is probably the best option.

I hope that helps,

Jochen Klier

National Instruments

[Marian_O]

Hello Kenzi,

thank you for posting at the National Instruments forum. You are looking for a reliable solution to control your expensive test rig.

Working with test rigs requires an extensive knowledge and wide experience in several areas (like safety, mechanics, electrical). Little changes or "trial and error" may result in irreparable damages, injury or even death! Please consider this, when learning Motion Control.

I have two ideas, to enhance the reliability:

a) LabVIEW Real-time: more reliable than "standard office PC" with LabVIEW, when used on a industry proofed platform
b) Jog inputs of P70530

a) What is LabVIEW Real-Time? (see http://zone.ni.com/devzone/cda/tut/p/id/5030)

"Most LabVIEW applications run on general-purpose operating systems like Microsoft Windows. Some LabVIEW applications require deterministic processing that non-real-time operating systems like Windows cannot guarantee. (...). LabVIEW Real-Time combines the ease of use of LabVIEW with the power of real-time systems so you can generate deterministic applications using graphical programming. These real-time applications run on LabVIEW Real-Time Series hardware, either plug in data acquisition devices or networked LabVIEW Real-Time Series devices.

The LabVIEW Real-Time Development System runs on Windows, just like LabVIEW. You develop all code in this environment and down load real-time code to run embedded applications on a hardware target. Embedded LabVIEW Real-Time applications do not have a user interface, so they must have a host PC to generate the user interface. General purpose operating systems can crash or hang, which causes programs to quit running. Because embedded LabVIEW Real-Time applications run on separate hardware, they do not stop executing if the host PC operating system crashes. If a crash occurs on the host PC operating system, the user interface is lost, and any communication between the embedded LabVIEW Real-Time application and the host PC ceases. However, embedded LabVIEW Real-Time applications continue to run. You can reboot the host PC without disrupting embedded LabVIEW Real-Time applications and reestablish communication between the host PC and LabVIEW Real-Time. (...)"

If you choose an appropriate embedded target, like Real-Time PXI (www.ni.com/pxi) or the FPGA based compactRIO (www.ni.com/crio), you will get a much more reliable platform. For example: you may program a "safety shutdown", which operates the vane.

b) If you just want to control the vane manually, the P70530 offers the possiblity to jog the stepper motor. Please take a look at the manual page 9 and 30:

P70530 (DC) High Performance Micro-stepping Drive

Reference Guide

https://www.ni.com/docs/en-US/bundle/372324d/resource/372324d.pdf

You wrote, that you are new to motion control. Maybe, you will find the following material useful:

Resource Kit für die Motorsteuerung: Grundlagen der Motorsteuerung

http://sine.ni.com/np/app/culdesac/p/ap/motion/lang/de/pg/1/sn/n17:motion/docid/tut-8838

The resource kit contains several documents for getting started, like presentations, white papers and so on.

[Kenzi]

Thanks to both of you! i think i am going to consider the option of the jog inputs on the Drive for manual control. Thanks once again