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SimInTech: what it is and how to quickly create an example

SimInTech is a visual modeling and simulation environment for dynamic systems, featuring a block editor and a built-in scripting language. It allows you to assemble diagrams from standard blocks, describe mathematics in scripts, and run numerical simulations with result saving and visualization.

Goals and requirements

  • What you will do:
  • Create a project and a minimal diagram.
  • Write a script with parameters and state variables.
  • Configure blocks and simulation parameters.
  • Run the simulation and see the plots.
  • What is required:
  • SimInTech installed (current version).
  • Basic understanding of linear models/state space (optional).

Step 1. Create a project

In the main SimInTech window, click "File" -> "New Project" -> "General model diagram".

New project

Step 2. Add a project script

Click the "Script" button in the project window and create a script. It is convenient to declare parameters here (e.g., matrices A, B, initial condition vector x0, integration step, etc.).

Project script

Step 3. Assemble the minimal diagram

Place the necessary blocks on the project canvas:

  • "Constant" from the "Sources" group -- setting the input signal;
  • "State Variables" from the "Dynamics" group -- implementing the system state (x_dot = Ax + Bu);
  • "Time Plot" from the "Data Output" group -- visualizing signals.

Connect the blocks with signal lines according to your structure (e.g., input U -> "State Variables" -> outputs X to the plot).

Minimal diagram

Step 4. Configure the "State Variables" block

Open the block parameters and initialize the fields with values from the script:

  • "Initial conditions" -> x0;
  • "Matrix A (Nx*Ny)" -> A;
  • "Matrix B (Nx*Nu)" -> B (and C, D if needed).

Check the matrix dimensions and consistency with the diagram.

State parameters

Step 5. Set the simulation parameters

In the project window, open "Simulation Parameters" and configure:

  • Simulation time interval (t0, t_end);
  • Integration step/method (fixed/variable);
  • Result saving frequency.

Simulation parameters

Step 6. Run the simulation

Click the "Run" button. Make sure the plots show the expected behavior. Adjust the parameters as needed and re-run the simulation.

Useful to remember

  • Save the project before running to preserve script changes.
  • For "stiff" systems, reduce the integration step or change the method.
  • Label signals and axes -- this will make result analysis easier.

Common issues and solutions

  • "Variable not found" at runtime:
  • Check that the variable name matches exactly and is defined in the script before the run.
  • Empty plots:
  • Verify the connections between blocks and the selection of displayed signals.
  • Matrix dimension error:
  • Compare the sizes of A, B, C, D with the number of inputs/outputs of the "State Variables" block.
  • Simulation is too slow:
  • Increase the step size (if acceptable) or simplify the model to the necessary minimum.

What's next

  • Integrating results and models with Python: see the "SimInTech to Python" section -- simintechToPython.md.
  • Examples of systems and controllers in TensorAeroSpace -- the "Examples" section in the documentation.