All about Modelica: An equation-based language for modeling physical systems

The reason for this is that the equations are extremely powerful (you can express pretty much anything computable inside an equation) and their numerical solution is often driven by heuristics (e.g., finding initial values). This makes it extremely difficult to come up with a common standard for the solution of Midelica's hybrid DAEs. Hence you will find little written information about what exactly happens during a simulation that applies to more than one implementation.

[1] https://github.com/ModiaSim/Modia.jl [2] https://youtu.be/hVg1eL1Qkws

I think the solvers are fantastic and produce better results, in terms of speed and scale, than any other method I had used previously, I was solving the DEs using either wolfram or Julia's Differential equations.

OpenModelica is a wonderful piece of software, I just wish it had a better UI, UX and error messages. Wolfram's system modeler offers an excellent experience but it is very expensive.

Recently I have been using Mathworks take on model-based languages, Simscape[1], which is great for my use case, as it integrates the whole MATLAB and simulink ecosystem. It is not modelica compatible, but it is possible to import FMUs created with modelica.

As a final note, I truly wished that Modelica was taught more in engineering and physics degrees.

[1] https://www.mathworks.com/products/simscape.html

As others have noted Modelica is both more abstract and more performant than a lot of other ways of describing multiphysics systems; it got its start in out-of-the-way places, which may explain it's relative obscurity, but there's an opportunity for it to become pervasive in engineering, both in the academy and industry.

At first I was mainly interested in it's ability to symbolically manipulate equations for me. With complex physical systems and interconnections it can become a tremendous chore rearranging systems to provide certain inputs and certain outputs. Modelica and the above compilers allowed me to specify the equations, and in fact automatically generate and interconnect larger and larger systems as one model. Specifying what were inputs and what were outputs became a simple few lines of code. For example, forward and inverse kinematics are the same equations in Modelica, you just specify different input/outputs, and the compiler determines what's the best way to do this. This can have significant challenges sometimes, when things don't easily work, but on the whole the process has been more often than not straightforward.

Interconnection of the models to other simulations has also become more and more a delight. Initially we had to depend on specific interfaces being built, either on the modelica interpreter side, or on the external application side (for example, Mathworks or Dymola), but fortunately the growth in such use prompted the modelica community to partner with industry to foster an open specification (like modelica is) for model exchange, called FMI. Integrating my models with external software is now a relatively straightforward task, still with challenges, but not expensive ones.

I'd highly recommend modelica and the various compilers as a means of creating very effective models; easily readable and therefore maintainable, re-usable, and now more and more deployable.

I, myself, have used them in the truck industry, CNC machine controls, flight systems, and in underwater vehicles and power systems. I routinely interact with people who use modelica in a much wider domain than this, and more and more in on-board systems, such as controllers. For example, I believe northern Germany uses modelica for its power controls for a significant portion of their country's energy supply.