An Entropy Framework for Communications & Dynamics Interdependency in Cyber Physical Systems: Analysis, Design, Implementation

Overview: Communication networks, which convey system measurements from sensors to controllers, play a key role in cyber physical systems (CPSs) such as smart grids, unmanned aerial vehicles (UAVs), and robotic networks. In contrast to traditional communication networks such as the Internet or cellular networks, CPS communication networks aims at stabilizing or optimizing the physical dynamics, thus re-quiring new theoretical foundations and design methodologies. In this project, the PI proposes to design system dynamics aware communication networks for CPS, which integrates the areas of communications, networking, control, and dynamical systems. The following tasks will be studied, ranging from theoretically optimal solution to practical implementations: (a) Joint Design as Hybrid Systems: The theory of hybrid systems will be used to model CPS, in which the operation mode of communication network is modeled as the discrete state of a hybrid system, while the physical dynamics are modeled using the continuous state. The communication and control sub-systems will then be designed jointly by optimizing the hybrid system dynamics; (b) Separate Design via Information Interface: In this task, the communication and control sub-systems are designed separately and are bridged via designated interfaces, such as commu-nication quality of service (QoS) or virtual queue mapping. The performance loss due to the separation will be studied; (c) Coexistence with Elastic Data Traffics: The realtime data traffic may share the same communication resource with elastic data traffics such as Internet data. The queuing dynamics of elastic data traffic and the physical dynamics of CPS will be integrated in the same framework, and the scheduling for the two types of traffics (elastic and realtime) will be studied; (d) Application and Implementation in Smart Grid: The principles, algorithms, and protocols obtained in the previous two tasks will be applied and substantiated in smart grids as a case study for CPS. The voltage control in microgrid, both centralized and decentralized, will be particularly studied. They will be implemented in both software simulation testbed, in which the communication and control sub-systems are co-simulated, and hardware testbed using USRP boards and the microgrid testbed at the Oak Ridge National Lab (ORNL).

Intellectual Merit: To the PI's best knowledge, there have not been any systematic study on the commu-nication network design in CPS, which endows the communication network the awareness of the physical dynamics state. The proposed research will bring a paradigm shift to studies on the communication net-work design for CPS, and will have a deep impact in the areas of communications, networking, control, and power grids. Since the proposed communication network is aware of the physical system state, it is expected to be substantially more efficient than traditional data communication network for the purpose of controlling CPS. Hence, it will bring significant benefits to the future development of CPS, particularly smart grids. Moreover, the principles for generic CPS proposed in this research can be widely applied in many other applications such as mobile sensor networks, autonomous robotic control, UAV networks and even queuing networks. The proposed research also opens a new dimension for the area of networking, since it provides many guidelines for application specific networking.

Broader Impact: For educational purposes, the PI will develop new courses based on the proposed re-search. Suitable topics in the proposed research will be designed for high school students in K-12 outreach. The PI will also attract underrepresented groups into the research project. The achievements of the pro-posed research will be disseminated to academia and industry via academic conferences and industrial connections, such as with the collaborators at ORNL and Qualcomm, Inc. The testbed built in this project will also enhance the research infrastructure at the University of Tennessee in Knoxville (UTK). It will serve as the communication subsystem of power grids, thus significantly contributing to the center for ultra-wide-area resilient electric energy transmission networks (CURENT) in the EECS department at UTK. It will also lead to substantial impact on everyday life and it helps to improve the agility and robustness of power grids and renewable energy generations.

Key Words: cyber physical system; communication network; smart grid