With faster computing capability of computers and reduced price of communication bandwidths, computation and communication can be embedded into physical objects to monitor their operations. Meanwhile, physical objects can in turn realize the environmental awareness and control with the aid of networks and computer components. This converged system of physical world and cyber world is called cyber-physical system, which is characterized by integrating computation, communication and physical process.¡¡
CPS can handle and integrate massive heterogeneous data stably and safely in complex environment, which has higher adaption and autonomous coordination. The architecture of CPS can be divided into four layers, namely, the perception layer, the network layer, the cognitive layer and the control layer. The perception layer consists of sensors and controllers, which is responsible for the perception of certain physical properties of the real world, such as temperature, humidity in agriculture and patient¡¯s blood pressure, pulse in telemedicine. The network layer is dedicated to connecting the objects in cyber world and physical world, realizing date exchange and supporting collaborative perception and control. Hence, this layer provides the CPS with real-time network services. By calculating, analyzing and reasoning sensory data, the cognitive layer can understand the real world properly and deeply. Based on the cognitive results, the control layer is able to determine control strategies, issue control instructions and command physical objects in long distance. Consequently, the four layers form a feedback loop control system.
The significance of CPS lies in that it connects physical objects to the internet and thus enables physical objects with computation, communication, precise control, remote coordination and self-government ability. From an application perspective, CPS covers not only the aspects of life that are closely related to the warehouse surveillance and smart home network, but also in the application of industrial control systems and intelligent transportation systems and other large systems are becoming increasingly widespread. If the popularity of the internet has changed the way people work and live, the universal application of CPS will change the way we interact with physical world and bring a new industrial revolution to human society.