model based control

[bcglaxer]

I'm having some difficulty creating a model of my plant in labview. I'm using Labview 8.2.1 Development System w/ the PID Toolkit and the Control Design Toolkit. Anyway, please see the attached figure for clarification. My plant has two inputs (Motor Torque and Load Angle) which, after passing through two transfer functions representing the plant and subtracting their outputs, yields one output (Load Torque). Motor Torque and Load Angle are known and I have the data expressed as a function of time. I've defined the transfer functions in a mathscript box and I've created controls to provide values to the symbolic parameters in the transfer functions, but I can't figure out how to connect the Motor Torque and Load Angle to the transfer functions or extract the Load Torque from them either. Can someone help me out?

Thanks,

Brian

[chris.b]

If you'd like to add the two models (TFs) you can use the CD Add Models.vi, located in Functions » Programming » Control Design and Simulation » Control Design » Model Interconnection » CD Add Models.vi.

Also, the example finder (Help » Find Examples) has some great example VIs, located in Browse » Toolkits and Modules » Control and Simulation » Control Design.

[bcglaxer]

In that case, would I just make the TF I want to subtract negative? How do I connect the input torques and angles for the TFs?

[chris.b]

Hi Brian,

In the same palette as CD Add Model is CD Subtract Model.  This function will subtract one model from another model (or transfer function, in this case).