Modeling Complex Systems with Subsystems in Simscape

Welcome back to the Physical Modeling in Simscape with Simulink & MATLAB blog series! This blog builds on the previous session, where we introduced subsystems. Today, we’ll explore modeling complex systems, such as engines, using Simscape. By leveraging subsystems and advanced blocksets, you’ll learn to design efficient, professional-grade models.

This tutorial is brought to you as part of Skill-Lync's Full Course on Simscape physical modeling. Whether you're a beginner or an advanced learner, this guide will help you tackle multi-domain systems with confidence.

Step 1: Understanding Engine Systems in Simscape

Engine systems are integral to many applications, including automotive and aerospace. Simscape provides blocks and libraries that allow you to model and simulate engines efficiently.

Exploring Engine Models:

• Open MATLAB documentation and search for "engine models."
• You'll find examples like Mapped SI Engine and Mapped CI Engine, part of the Powertrain Blockset.
• These models include essential components like air-fuel ratio, engine torque, and power demand curves.

Powertrain Blockset:

• The Powertrain Blockset offers high-level models tailored for automotive systems.
• Explore predefined systems that include engines, transmissions, and vehicle dynamics.

Step 2: Building a Simple Engine Subsystem

• Adding a Generic Engine Block:
• Search for Generic Engine in Simulink’s library browser.

This block provides a simplified representation of an engine, with parameters like throttle, power, and torque.

Configuring the Engine Block:

• Adjust input parameters such as throttle input and speed to simulate different engine behaviors.
• Use lookup tables to define engine characteristics, such as torque curves and efficiency maps.

Creating Subsystems for Components:

• Group related blocks (e.g., engine, throttle control) into a single subsystem.
• Label the subsystem “Engine System” for clarity.

Step 3: Analyzing Advanced Subsystems

Looking Under the Mask:

• Right-click on a subsystem and select Look Under Mask to explore its internal structure.

For Simscape blocks, the source code may be accessible, providing insight into how the block is implemented.

Exploring Hierarchical Models:

Subsystems often contain additional subsystems, creating a hierarchy. For example:

1. Vehicle Model Subsystem: Includes dynamics, aerodynamics, and tire forces.
2. Engine Subsystem: Includes torque generation, air-fuel ratio, and exhaust calculations.

Step 4: Creating Custom Subsystems

Vehicle Body Example:

• Add the Vehicle Body block from the Simulink library.
• Create a custom subsystem that includes the vehicle body, engine, and transmission.

Aerodynamics Subsystem:

• Add the Aerodynamic Forces and Moments block.
• Use the Look Under Mask feature to study how MATLAB implemented the block with basic Simulink components.

Step 5: Practical Tips for Subsystem Design

• Rename Subsystems: Use descriptive names like “Gear Transmission” or “Engine Model” for clarity.
• Add Images: Assign custom images to subsystems for a professional look.
• Use Help Documentation: MATLAB’s help files provide valuable insights into block configurations and subsystem types.

Conclusion

In this blog, we explored how to model complex systems, such as engines and vehicles, using subsystems in Simscape. By understanding Simscape modeling workflow and exploring block hierarchies, you can tackle intricate designs with ease.

To master these skills, enroll in Skill-Lync’s Simscape Certification Course, which covers everything from basic tutorials to advanced engineering applications. With hands-on projects and personalized support, you’ll be ready to take on real-world challenges.

Stay tuned for more insights in the next blog, where we’ll delve deeper into vehicle modeling and subsystem applications in Simscape!

This blog is part of our ongoing Physical Modeling in Simscape with Simulink & MATLAB. If you missed the previous posts, check them out here.

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