Simulate the plant behaviour in real-time

[gomezramones]

I'm a little concern about a problem that I have at this moment. I'm doing a project in a company who wants a design of a rudder control system for a ship. I finish the design and I did it on LabVIEW with the Control Design VI in a Simulation Loop. That was the easy part of the project but the company told me that they want a project where they can use it in the reality, so I have to simulate in real-time the ship and I can't use the simulation loop, beside I must to simulate two sensor with CompactRIo (compass and Synchro) and send it in any communication protocols to a computer. I know there is a VI where I can use to simulate a lag-leag controller.

The problems I have are: How to implement a plan equation with the help of Transfers Function? How to implement a integrator (1/s) in real-life? ( I had seen that you comment the possibility on use deadband). The last question, how to simulate the two sensor that I mentioned previously with CompactRIO?

[andmboa7]

Hello Hello gomezramones

Can you look into these documents: 

Sensor Simulation on FPGA Hardware

http://www.ni.com/newsletter/50172/en/ 

High Throughput Reciprocal Function

https://www.ni.com/docs/en-US/bundle/lvfpga-api-ref/page/vi-lib/rvi/fxpmathlib/fxpreciprocal/xnode/n...

[wiebe@CARYA]

I'm no VeriStand expert, but I think it's exactly for your situation. In general, it won't be a small thing. Making such a simulation might easily double, triple or quadruple (or more) your required efforts.

I tried to understand this stuff myself (a few times). This book might help, but it's not easy: Control Systems Engineering, Norman S. Nise. MIT has opencourseware, which might give a hint about the level of this stuff.

Q1) How to implement a plan equation with the help of Transfers Function?

Well, that is what system identification is for. I'm afraid I can't help you much. And I doubt if anyone can help you do that remotely. It's an field of expertise, you might look for an expert.

You'll either have to make physical models and convert them to Z-domain, or analyse the system and get the "system's identification" (transfer functions) from them.

Q2) How to implement a integrator (1/s) in real-life? ( I had seen that you comment the possibility on use deadband).

Well, add the new value to the old value, and you'll have an integrator. That is in time domain.

Also, a simple feedback node can change it's appearance to 1/z (Appearance>Z-Node Delay Node). AFAIK, That works as integrator in Z-Domain (sort of digital Laplace, in layman's terms).

Q3) The last question, how to simulate the two sensor that I mentioned previously with CompactRIO?

There are as much solutions to this as there are programs.

For me, making a parent class with a physical child and a simulation child would work. A totally different solution would be to add a waveform generator to the input, and you'll have a simulated sensor. If you use shared variables, you might be able to "force" there values into simulated values (set by a simulation program).

[gomezramones]

I know how to implement the plant behavior with CDSIM help. If you go to C:\Program Files\National Instruments\LabVIEW 2014\vi.lib\addons\control\advanced, you'll find blocks of transfer function and they only use LV code.

Thank you for the help