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a question about fluidic sys. in Verilog-AMS (Read 4247 times)
lily
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a question about fluidic sys. in Verilog-AMS
Dec 17th, 2003, 8:45pm
 
???
Hi,

Does anyone know how to describe the fluidic system in Verilog-AMS? I cannot find any "discipline" or "nature" corresponding to it. However, I know VHDL-AMS has Fluidic nature.

Thanks,

lily
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Ken Kundert
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Re: a question about fluidic sys. in Verilog-AMS
Reply #1 - Dec 17th, 2003, 11:03pm
 
I don't believe there is a fluidic discipline available from "disciplines.vams". However, it is relatively easy to create your own natures and disciplines.

-Ken
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lily
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Re: a question about fluidic sys. in Verilog-AMS
Reply #2 - Dec 18th, 2003, 12:01am
 
Cheesy

Thanks for your reply! Do you have any example about how to create it and the corresponding access function  etc. ?

lily
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Ken Kundert
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Re: a question about fluidic sys. in Verilog-AMS
Reply #3 - Dec 18th, 2003, 8:02am
 
I can give you and example of the syntax, but I am not familiar enough with fluidic systems to be able to choose the right quantities, units, and tolerances.

First you have to define the natures. These describe the signals that you will be using. In fluidic systems, I'm guessing that the models will be formulated in terms of pressure and flow or flow rate. You would probably use flow if the fluidic movement were a finite displacement, and flow rate if were a constant stream. The natures might look something like these ...

// Pressure in Newtons per square meter
nature Pressure
     units = N/m^2;
     access = P;
     abstol = 1p;
endnature

// Flow in cubic meters
nature Flow
     units = m^3;
     access = F;
     abstol = 1p;
endnature

// Flow rate  in cubic meters per second
nature FlowRate
     units = m^3/s;
     access = FR;
     abstol = 1p;
endnature

You will definitely need to adjust the abstols for these natures. Choose the largest signal level that is always negligible as your abstol. Choosing it too large reduces accuracy, choosing it too small can cause convergence problems.

Finally, you need disciplines, which are nothing more than a pairing of natures.

// Displacement Fluidic
discipline displacement_fluidic
     potential Pressure;
     flow Flow;
enddiscipline

// Stream Fluidic
discipline stream_fluidic
     potential Pressure;
     flow FlowRate;
enddiscipline

-Ken
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