Cyber Physical Systems

Cyber Physical Systems

1. Cyber physical systems

Cyber physical systems are a collection of computing devices communicating with each other and the

outside world through sensors and actuators. These devices interact with the outside world through a

feedback loop.

1.1 Features of cyber physical systems



Reactive computation: As opposed to traditional computation model, where the outputs

produced are directly dependent on the inputs, the reactive computation model focuses on a

system interacting with the environment to determine its inputs and outputs.



Concurrency: There exist multiple threads of execution running concurrently, exchanging

information with each other and executing in parallel thereby, achieving concurrency.



Feedback control of the physical world: The physical systems interact with the outside world

through a feedback loop. The devices measure the environment (of the outside world) through

sensors and then, influence it in some way through actuators.



Real time computation: Since, most of the cyber physical systems are used in safety critical

systems such as a cruise controller, flight management computers and so on, timing

requirements are paramount in such systems. Hence, the real time performance of these

systems is a very important feature.

2. Synchronous model





There are two kinds of components in cyber physical systems:

Functional components whose behavior (or the output produced) could be described as a

mathematical function by mapping the inputs and outputs.

Reactive components which maintain a consistent internal state, interact with the outside

environment via inputs and outputs (through sensors and actuators) in an ongoing manner.

A synchronous model is a good example of reactive component. In this system, the components

execute in a staggered manner (in a series of rounds). In each round, the system reads the input

and based on the current internal state and inputs, computes the...