Behavior Diagrams for Model-Based Systems Engineering (MBSE): State Machine Diagrams
From the series: Behavior Diagrams for Model-Based Systems Engineering (MBSE)
This third part in the MBSE Behavior Diagrams series explores state machine diagrams, which are crucial for systems with multiple modes of operation. These diagrams capture the system’s states and the criteria for transitioning between them, ensuring an accurate representation of system behavior under various conditions. State machine diagrams help in defining system states and transitions, preventing undesirable states such as shifting a car from “drive” to “park” while in motion. Note: This diagram requires Stateflow®.
Published: 12 Aug 2024
Visually describing the dynamics of a system and how it should interact with its environment using behavior diagrams is a significant benefit of model-based systems engineering. Driving those diagrams with a modeling and simulation engine maximizes their effectiveness in helping to create implementable requirements and convey design intent to downstream functional teams. In this video, we will review state machine diagrams, when to use them, and how employing them in System Composer helps to ensure system engineering and design processes remain in sync.
Many systems have different modes of operation or states. Those states can change sequentially, such as transitioning from startup to running, or based on external factors or commands, such as engaging or disengaging an autopilot. Systems often perform different functions depending on their active state. That's why it's important to accurately capture which state the system should be in at any given time and what the criteria are for transitioning to different states. For example, you would not want to be able to shift your car from drive to park when the vehicle is in motion.
State machine diagrams or state charts are commonly used for describing just that. The state chart describes which set of functions or activities should currently be performed. MathWorks tool state flow can be used to enumerate the possible states, what occurs in each state, and how transitions between states are defined. You can even nest your states of operation to describe complex systems.
There are two main benefits to using Stateflow with System Composer. The first is that by using a common MBSE and design environment, your system behavior, structures and implementation can exist together. This means that you can define behaviors of components directly in your MBSE tool.
The second benefit is that the state machine is simulatable, meaning you can run automated testing and verification of completeness and correctness of your requirements. And once you have a design that satisfies the requirements, Stateflow allows for automatic production-ready code generation so no errors will be introduced by hand-coding. Executable state charts make it easier to describe and implement the intended behavior of complex systems, saving valuable program time and rework. This is just the tip of the iceberg for MathWorks state machine diagramming tool Stateflow. If you'd like to learn more, check out our Solutions page or the Stateflow Product page. And don't forget to check out our other behavior diagram videos. Thanks for tuning in.