Real-world examples of state machines in action

Have you ever wondered how your everyday devices operate seamlessly without any hiccups? How does your washing machine know when to start, stop and spin? How does your phone switch seamlessly between Wi-Fi and mobile data? The answer to all these and many more such questions lies in the concept of state machines.

State machines are the foundation of modern computing and have revolutionized the way we interact with our devices. A state machine is a mathematical model consisting of a finite set of states, transitions, and actions. Simply put, it's a machine that changes its behavior based on its internal state and external inputs.

In this article, we'll dive deeper into the concept of state machines and explore real-world examples of how they're used in action.

The basics of state machines

Before we dive into the examples, it's worthwhile to understand the basics of state machines. As mentioned earlier, a state machine is nothing but a mathematical model consisting of:

• States: A finite set of possible states that a machine can be in.
• Transitions: A set of possible transitions that can be made from a given state based on external inputs.
• Actions: Actions that can be taken when a transition is made.

Let's take an example to understand this better. Consider a traffic light. The traffic light has two possible states - Green and Red. The possible transitions between these two states are:

• Green -> Red, when the timer expires.
• Red -> Green, when the timer expires.

Finally, the actions associated with these transitions are:

• Green -> Red: Change the light to red and start the timer for the red light.
• Red -> Green: Change the light to green and start the timer for the green light.

Here, the timer is an external input that triggers the transition between the two states. The actions associated with the transitions are pretty straightforward.

Real-world examples of state machines in action

Now that we've understood the basics of state machines, let's explore some real-world examples.

1. Washing machine

A washing machine is a perfect example of a state machine. A washing machine has three possible states:

• Wash
• Rinse
• Spin

The possible transitions between these states are:

• Wash -> Rinse, when the wash cycle completes.
• Rinse -> Spin, when the rinse cycle completes.
• Spin -> Done, when the spin cycle completes.

Finally, the actions associated with these transitions are:

• Wash -> Rinse: Drain the wash water and fill the rinse water. Also, start the timer for the rinse cycle.
• Rinse -> Spin: Drain the rinse water and start the spin cycle. Also, start the timer for the spin cycle.
• Spin -> Done: Drain the spin water and stop the timer.

Here, the completion of each cycle is an external input that triggers the transition between states.

2. Elevator

An elevator is another great example of a state machine. An elevator has four possible states:

• Stopped
• Moving up
• Moving down
• Opening doors

The possible transitions between these states are:

• Stopped -> Moving up, when the up button is pressed.
• Stopped -> Moving down, when the down button is pressed.
• Moving up -> Stopped, when it reaches the top floor.
• Moving down -> Stopped, when it reaches the ground floor.
• Stopped -> Opening doors, when it reaches the desired floor.

Finally, the actions associated with these transitions are:

• Stopped -> Moving up: Start the elevator and move it up. Also, start the timer for the movement.
• Stopped -> Moving down: Start the elevator and move it down. Also, start the timer for the movement.
• Moving up -> Stopped: Stop the elevator and reset the timer.
• Moving down -> Stopped: Stop the elevator and reset the timer.
• Stopped -> Opening doors: Open the doors and start the timer for closing.

Here, the press of each button and reaching the desired floor are external inputs that trigger the transitions.

3. Mobile networks

Mobile networks use state machines extensively to provide seamless connectivity to millions of users. If you've ever wondered how your phone switches between Wi-Fi and mobile data seamlessly, it's all thanks to state machines.

A mobile network has two possible states:

• Wi-Fi
• Mobile data

The possible transitions between these states are:

• Wi-Fi -> Mobile data, when the Wi-Fi signal strength falls below a certain threshold.
• Mobile data -> Wi-Fi, when a Wi-Fi signal is available.

Finally, the actions associated with these transitions are:

• Wi-Fi -> Mobile data: Disconnect from Wi-Fi and connect to mobile data.
• Mobile data -> Wi-Fi: Disconnect from mobile data and connect to Wi-Fi.

Here, the signal strength of the Wi-Fi network is an external input that triggers the transitions.

Conclusion

State machines are a powerful concept that has revolutionized the way we interact with our devices. They're used extensively in modern computing and have made our lives much easier.

In this article, we explored some real-world examples of state machines in action. From washing machines to elevators to mobile networks, state machines are all around us, making our lives simpler and more seamless.

If you're interested in learning more about state machines, check out our website statemachine.events. We have a wealth of information on state machines and their practical applications.

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