DSHplus RT

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Nowadays Hardware-In-the-Loop (HIL) is an established test procedure, e. g.  for electronic control units (ECUs).  Such a HIL-test is done by connecting the ECU(s) with a simulator. Simulation models therefore have to run in real-time, which puts high demands on physically modeled system components. Often FLUIDON is asked:

Are DSHplus models real-time capable?

The honest answer is: in general DSHplus models are real-time capable, but in the end it depends on the application.

Why such a sibyllic answer?

On the software part DSHplus offers everything necessary for real-time capable simulation models. The graphical model is converted into source code which can be used by real-time applications. Parameters, initial values, look-up tables and numerical properties can be exported as ASCII-files, handling routines and integrators are available as 32bit and 64bit libraries for Windows and Linux. The infrastructure is there:

So where is the problem?

Actually there is no problem! The challenge lies in the broad variance of user specific level of detail. Two examples:

When analyzing pressure pulsations of hydraulic lines (industrial systems, construction machinery, automotive braking systems etc.) the pipe and hose models need a certain amount of discrete internal elements which increases calculation time. Same is true for the necessary small step size to get the desired resolution to resolve frequency dependent effects. If the available simulator hardware can’t cope with these demands real-time is no more.

In a numerically otherwise simple system a detailed physically modeled valve, build by using the Micro Component Library or a user specific component, is introduced. The component’s parameters are necessarily dictated by the real counterpart’s properties to accurately represent the dynamic behavior. This means small internal hydraulic volumes (capacities), metering edges (high but stroke dependent variable resistances), small gaps (leakage resistance) and an only marginally damped spring-damper-system to model the valve spool. Mathematically this results in a so called “stiff” equation system, which calls for a very small simulation step size and there goes real-time again.

What kind of solution is FLUIDON providing?

Being specialized for detailed dynamic analysis of hydraulic systems DSHplus more often than not demands rework of validated models (reduction, simplification) to gain real-time capability.

FLUIDON opted therefore to remove the automatic real-time export of simulation models in the standard edition, although the possibility is of course still available in the software. To substitute for this FLUIDON offers each customer an individually tailored counseling for his real-time application. Naturally FLUIDON will also create real-time models in the course of project services.

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