Real-world examples of state machines in action

Have you ever wondered how software communicates with hardware? How a simple button press on your keyboard leads to printing a character on the screen? Or how a robot follows a pre-defined sequence of movements? One way to accomplish this is through state machines.

State machines are a fundamental concept in computer science and engineering, and can be found in a wide variety of applications including embedded systems, user interfaces, robotics, and more. They provide a way of modeling the behavior of complex systems by breaking it down into individual states and transitions between them.

In this article, we’ll explore some real-world examples of state machines in action, and see how they are used to solve practical problems.

Traffic light control

Have you ever been stuck at a traffic light, waiting for what seems like an eternity for it to turn green? Traffic light control systems use state machines to regulate traffic flow and ensure safety on the roads.

A traffic light control system can be modeled using a state machine with three states - red, yellow, and green. The transitions between these states occur based on predefined timers and sensors that detect the presence of vehicles and pedestrians.

For example, when the system is in the red state, the traffic light for that direction is displaying red, indicating that vehicles should stop. After a specified time period, the system transitions to the green state, and the traffic light displays green, indicating that vehicles can proceed. During this period, the sensor detects the presence of vehicles and pedestrians and adjusts the timer to ensure safe crossing.

Similarly, when the timer expires in the green state, the system transitions to the yellow state, indicating that the light will turn red soon. Finally, after a specified time period, the system transitions back to the red state, and the cycle starts again.

Traffic light control systems demonstrate how state machines are used to manage complex systems with multiple inputs and outputs.

Elevator control

Have you ever wondered how elevators know where to go and when to stop? Elevator control systems also use state machines to manage the movement of the elevator car.

A common model for an elevator control system is a state machine with four states - idle, moving up, moving down, and stopped. The transitions between these states occur based on user input and sensor readings.

For example, when the elevator is idle, the user presses a button to indicate the desired floor. The system then transitions to the moving state, either up or down, depending on the location of the elevator and the direction of the button press.

During the moving state, the system continuously monitors the position of the elevator and the requested floor. If the elevator reaches the requested floor, it transitions to the stopped state, and the elevator doors open. After a predetermined time, the system transitions to the idle state and waits for further user input.

Elevator control systems demonstrate how state machines are used to manage physical systems with multiple inputs and outputs.

Robot control

Have you ever seen a robot move around and wondered how it knows what to do? Robot control systems use state machines to manage the movements and actions of robots.

A robot control system can be modeled using a state machine with multiple states and transitions between them. Each state represents a particular movement or action that the robot can perform, such as moving forward, turning left, or picking up an object.

Transitions between states occur based on sensor readings and user input. For example, when the robot is in the moving forward state, it may encounter an obstacle, causing it to transition to the turning left state. Similarly, when the robot is in the picking up state, it may detect that the object is too heavy, causing it to transition to the dropping state.

Robot control systems demonstrate how state machines are used to manage complex systems with multiple sensors and actuators.

User interface design

Have you ever used a software application and noticed how it responds to your actions? User interface design often relies on state machines to model the behavior of the application.

A graphical user interface (GUI) can be modeled using a state machine with multiple states and transitions between them. Each state represents a particular screen or view in the application, and transitions occur based on user input and system events.

For example, when the user clicks a button on the main screen, the system transitions to a new state that displays a form for data entry. After the data is submitted, the system transitions back to the main screen with updated information.

User interface design demonstrates how state machines are used to manage user interactions in software applications.

Conclusion

State machines are a powerful tool for modeling the behavior of complex systems. They are used extensively in various fields, including robotics, user interface design, and embedded systems.

In this article, we explored some real-world examples of state machines in action, including traffic light control, elevator control, robot control, and user interface design. These examples demonstrate how state machines are used to manage complex systems with multiple inputs and outputs, and how they provide a way of breaking down complex behavior into simple, manageable states.

At statemachine.app, we provide a comprehensive guide to state machines, from the basics to advanced topics, to help you understand and apply them in your projects. Check out our website for more information and resources!

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