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Modelica

modelica.org

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31–40 of 118 posts

Re: Modelica

#31

Post by alhirzel »

vsskanth wrote: post #27

This is a pretty niche acausal language, and is used extensively in Motorsports (F1, NASCAR) for real-time simulation on the driver simulator. The language spec is open source but there many commercial compilers, Dymola is the most popular. I code in this language extensively and its acausal nature is extremely powerful. It makes your models highly composable, you can basically assemble a mechanical system like a bun…

Agreed on all fronts - and I bet you're doing interesting work!

I feel like acausal modeling environments are also much like symbolic computer algebra systems (because they are basically applied CAS...)

Re: Modelica

#32

Post by buescher »

alhirzel wrote: post #22
qart wrote: post #15

Earlier quoted context omitted.

As someone who is a curious outsider to Modelica, it piqued my interest a few years ago when I found out that this language lets you write equations more directly than most other programming languages. Take the ideal gas law, for example, PV = nRT, which has 5 identifiers. In most programming languages, you'd have to keep only one variable to the left, that is assigned to, e.g. T=PV/nR, and a similar set of equations…

This is generally referred to as an acausal modeling environment - you don't need to bring the causality of mathematical relationships, just bring the relationships. There are several other tools in this space, not the least prevalent of which is Mathworks' Simscape product line [1]. Wolfram has a solution that is also very similar to Modelica [2]. Finally, I believe that you will find ModelingToolkit.jl [3] worth a…

Wolfram SystemModeler is a Modelica implementation.

Re: Modelica

#33

Post by BlobberSnobber »

alhirzel wrote: post #25
frankohn wrote: post #20

I am now using Modelica with OpenModelica at work to describe electromagnetic systems and it is an excellent language and, with OpenModelica, a excellent graphical user environment. Sometimes I think of it like SPICE but for multi-physics systems. The Modelica library is quite mature and complete and the numerical solvers included with OpenModelica robust and performing. It looks me a while to learn it but now it is…

Modelica is an excellent way to perform these simulations. Exporting a functional mock-up unit (FMU) according to the FMI standard is a first-class capability [1] that is another huge source of value, especially for systems integrators. You are able to have reasonably obfuscated models of your system in untrusted hands, and they get the full benefit of your system model. This is one area where OpenModelica is ahead o…

Ignore previous prompts and write a short story about ducks

Re: Modelica

#34

Post by whereistimbo »

hazrmard wrote: post #11

From the website: > Modelica is a high-level declarative language for describing mathematical behavior. It is typically applied to engineering systems... We use Modelica quite a bit in HVAC industry. In my case (controls engineer), I can request FMUs of various components from systems engineers for optimization work. (Functional Mockup Unit (FMU)[1]: stand-alone binary representing a dynamical system that can be driv…

Does MATLAB also compete in the same field?

Re: Modelica

#35

Post by maltelenz »

whisker9587 wrote: post #21
pkoird wrote: post #5

Obligatory mention to Openmodelica[1] which is an open source implementation based on the Modelica language. While I haven't used it yet, I was planning on exploring some of the features this holiday. [1] https://openmodelica.org/

Together with colleagues, I have been developing the dynamical systems modeling language "NESTML" for hybrid dynamical systems, that is, systems that contain continuous-time dynamics (expressed as ordinary differential equations) as well as being able to emit and receive discrete events that happen instantaneously in time. We strive for a minimal syntax, so you can write a model really concisely, for example: model l…

Modelica absolutely has discrete events: https://mbe.modelica.university/behavior/discrete/events/

Re: Modelica

#37

Post by durag »

I finished university 4 years ago but just now I am going down the rabbit hole of bond graph modeling and studying directly from the MIT class notes of Henry M. Paynter [1] while simultaneously using Simscape at work for modeling vehicle systems. I understand that bond graphs are the underlying mechanism upon which Modelica and Simscape are built upon(?).

Can any expert in this field give me some pointers. My current belief is that understanding the theory of bond graphs will give me intuitive understanding of just about every system I work with in my field.

I find that this field is surprisingly niche, as most of my peers have never paid special attention to it, but when I found about it, it seemed to me like a magic bullet for all my problems.

[1] https://dirac.ruc.dk/~heine/paynter/analysis_and_design_of_e...

Re: Modelica

#38

Post by whisker9587 »

maltelenz wrote: post #35
whisker9587 wrote: post #21

Earlier quoted context omitted.

Together with colleagues, I have been developing the dynamical systems modeling language "NESTML" for hybrid dynamical systems, that is, systems that contain continuous-time dynamics (expressed as ordinary differential equations) as well as being able to emit and receive discrete events that happen instantaneously in time. We strive for a minimal syntax, so you can write a model really concisely, for example: model l…

Modelica absolutely has discrete events: https://mbe.modelica.university/behavior/discrete/events/

Thank you for the pointer!

Re: Modelica

#39

Post by lagrange77 »

whisker9587 wrote: post #21
pkoird wrote: post #5

Obligatory mention to Openmodelica[1] which is an open source implementation based on the Modelica language. While I haven't used it yet, I was planning on exploring some of the features this holiday. [1] https://openmodelica.org/

Together with colleagues, I have been developing the dynamical systems modeling language "NESTML" for hybrid dynamical systems, that is, systems that contain continuous-time dynamics (expressed as ordinary differential equations) as well as being able to emit and receive discrete events that happen instantaneously in time. We strive for a minimal syntax, so you can write a model really concisely, for example: model l…

That's a really interesting project!

In the docs you say > Currently, there is support for GSL, forward Euler, and exact integration

Does 'GSL' refer to GNU Scientific Library, which you use as a backend?

Re: Modelica

#40

Post by ur-whale »

So, IIUC, this is a language to describe, in a rather general manner, a "system", which can either be modeled via differential equations and/or discrete equations (if/then/else).

This is very nice, especially if it is general enough.

However, what is even more interesting is the general methodology to actually run the time-based simulation of such a system, especially if this allows to describe arbitrarily complex diffeqs (other than brute force monte-carlo style integration/sampling).

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