SysSimX Documentation

SysSimX is a free and open-source Python library for system simulation. It allows you to build hybrid and heterogenous system models by connecting system component models from different environments, including:

• FMU Components - Functional Mock-up Units (FMI 2.0 Co-Simulation)

• OpenSim Components - Musculoskeletal biomechanics models using OpenSim

• FEM Components - Finite Element Models using NGSolve

• Custom Python Components - User-defined models implemented directly in Python

Note

SysSimX targets researchers and engineers who need to couple multi-physics models across simulation environments, especially in mechanical, electrical, and biomechanical systems.

Start Here

• Want to install syssimx? See Installation.

• New to syssimx? Read the Quickstart and Concepts.

• Looking for APIs? Jump to the SysSimX Package.

• Want hands-on learning? Go to Fundamentals.

• Interested in tool integration? Check out Modelica / FMU, OpenSim, Netgen/NGSolve, and Master Pendulum (MultiComponent).

• Curious about a case study? See Controlled Pendulum Case Study Overview and subsequent chapters.

Quick Example

from syssimx import System, Connection
from syssimx.components import FMUComponent

# Create and configure components
pendulum = FMUComponent("Pendulum", fmu_path="Pendulum.fmu")
controller = FMUComponent("PID", fmu_path="Controller.fmu")

# Build system with connections
system = System(name="ControlledPendulum")
system.add_component(pendulum)
system.add_component(controller)
system.add_connection(Connection(
    src_comp="Pendulum", src_port="angle",
    dst_comp="PID", dst_port="measurement"
))

# Run simulation
system.initialize(t0=0.0)
system.run(t0=0.0, tf=10.0, dt=0.001)

Key Features

Graph-Based Execution

Automatic dependency analysis with direct feedthrough and algebraic loop detection. Components are executed in topologically sorted order.

Algebraic Loop Handling

Detection and iterative solving using the Interface Jacobian-based Co-Simulation Algorithm (IJCSA).

Hybrid Co-Simulation

Event detection via zero-crossing indicators with bisection-based time localization and superdense time semantics.

Multiple Master Algorithms

Choose from Jacobi (parallel), Gauss-Seidel (sequential), or Hybrid (event-driven) algorithms.

Multi-Tool Integration

Seamlessly connect FMUs, OpenSim models, and NGSolve FEM models in a single system.

Multi-Model Switching

Dynamically switch between multiple models of the same component during simulation.

Unit-Aware Connections

Automatic unit conversion between ports using Pint.

Extensible Components

Implement custom components in Python or wrap external tools and FMUs.

Contents

Getting Started

• 1. Installation
• 2. Quickstart
• 3. Concepts

API Reference

• SysSimX Package
• Core Modules
  • CoSimComponent Base Class
  • Ports
  • Events
  • History
  • Multi-Component
• Co-Simulation Components
  • FMU Component
  • FEM Component
  • OpenSim Component
• System
  • Connection
  • System Class
• Master Algorithms
  • Algorithm
  • Jacobi Co-Simulation Algorithm
  • Gauss-Seidel Co-Simulation Algorithm
  • Interface Jacobian-based Co-Simulation Algorithm
  • Hybrid Co-Simulation Algorithm
• Utilities
  • Units
• Visualization Utilities
  • System Graph Visualizer

Core Tutorials

• Fundamentals
  • 1. Simple Pendulum Component
  • 2. Importing FMUs for Co-Simulation
  • 3. Simple System
• Intermediate
  • 1. Comparing Jacobi and Gauss-Seidel Algorithms
  • 2. Algebraic Loop System
  • 3. Simple Hybrid System
• Advanced
  • 1. Event Chain Handling
  • 2. Strong Event Simultaneity
  • 3. Internal Event Reporting

Tool Integration

• Modelica / FMU
  • 1. Modelica Pendulum: Basics
  • 2. Modelica Pendulum: Discrete Contact
  • 3. FMU: Rollback Mechanism
  • 4. Hybrid FMU Integration: Event-Driven Pendulum Simulation
• OpenSim
  • 1. OpenSim Pendulum: Basics
  • 2. OpenSim Pendulum: Torque Application
  • 3. OpenSim Pendulum: Contact Handling
• Netgen/NGSolve
  • 1. FEM Pendulum: Basics
  • 2. FEM Pendulum: Torque Application
  • 3. FEM Pendulum: Contact
• Master Pendulum (MultiComponent)
  • Motivation: why multiple models for one pendulum?
  • What is a MultiComponent?
  • MasterPendulum: one interface, three implementations
  • Workflow: building your own multi-model component
  • Why switch models at runtime?
  • State synchronization: the “hard part”
  • Practical guidelines (what to verify early)
  • Tutorials

Case Study

• 1. Controlled Pendulum Case Study Overview
• 2. Baseline System Model
• 3. Quantization and Sampling
• 4. Algebraic Loop
• 5. Discrete Rigid Contact
• 6. Multi-Model Switching with Contact

Other Links

• FMI Standard
• Modelica Documentation
• OpenModelica Documentation
• OpenModelica Connection Editor
• NGSolve Documentation
• OpenSim Documentation
• OpenSim Creator

Indices and Tables

• Index

• Module Index

• Search Page