Cyber Physical Systems Chapter 3 Quiz

Cyber Physical Systems (CPS)

• CPS is a system that integrates computer, communication, and physical systems.
• CPS systems are complex and involve a wide range of components.

Chapter 3: Discrete Dynamics, State Machines

• Discrete systems are systems where the variables can only take on discrete values.
• State machines are models that represent discrete systems.
• Continuous systems—systems where variables can change continuously.
• Hybrid systems–systems that combines continuous and discrete systems
• Diagrams illustrated discrete, continuous, and hybrid systems
• Example of a "tick" generator (timer):
  • Models how a timer triggers a 'tick' every T time units.
  • Shows the relationship between the timer and the tick.

Timed Automata

• An alternative to FSMs focusing on time explicitly.
• Timed Automata are a special case of hybrid systems.
• Explicitly shows timing between states via guard/output clauses and set actions.

Example: Mouse Double Click Detector

• Shows an example using a continuous variable and discrete inputs/outputs.

Timed Automaton Model of a Traffic Light Controller

• Illustrates a traffic light that changes based on the absence or presence of an input from a pedestrian.

• Shows green, red, yellow, and pending light states, durations

Hybrid Automata Reactions

• Reactions occur continually and are updated continuously based on the value of the continuous state variable.

Chapter 5: Composition of State Machines

• Explains two types of composition:
  • Spatial: Describing how components relate and communicate
  • Temporal: Describing when components are activated.
• Discuss concurrent states, and synchronous vs asynchronous concurrency.

Hybrid Systems and Sequential Composition

• Hybrid systems allow for sequencing between different modes (states).

Concurrent Composition

• For concurrent composition, need interfaces to combine inputs and outputs of machines.
• Concurrent: happening at the same time

Spatial Composition of State Machines

• Explains different ways to combine state machines spatially:
  • Side-by-side composition
  • Cascade composition
  • Feedback composition

Synchronous Composition

• State machines react together in lock-step.
• States of machines are combined as a Cartesian product

Asynchronous Composition

• State machines react independently.
• System reacts to each of the transitions independently.

Cascade Composition

• States machines composed where the output port(s) of the first machine are connected to the input port(s) of the second machine.

Time-Triggered Pedestrian Light

• An example of a timed automaton.
• Illustrates a light that stays green for a fixed time before turning red and repeating.

Time-Triggered Car Light

• A further example of a time-triggered automaton for a traffic light system;
• Includes a pedestrian input.

Pedestrian Light with Car Light

• Shows a composite machine of the pedestrian and car light states
• Analyzes the size of the composite state space.

Synchronous Cascade Composition

• Shows how state machine can be combined to make larger machines.
• Shows example of a combined system with a possible unsafe states

Synchronous Composition with Unreachable States Removed

• Shows state composition machine.
• All unreachable states have been omitted.

Feedback Composition

• A method of combining state machines where the output of one machine is the input to another, creating a feedback loop.

Hierarchical State Machines

• Illustrate how complex systems can be composed of hierarchical sub-systems.
• Shows transitions between state machine sub-components

Equivalent Flattened State Machine

• Every hierarchical state machine can be presented as a simple (flat) state machine.

Test your understanding of discrete dynamics, state machines, and timed automata as part of cyber physical systems. This quiz covers the key concepts including discrete and continuous systems, along with their representations and functionalities. Challenge yourself with examples such as the timer 'tick' generator.