Cyber-Physical System (CPS), which is used in various fields, has received increasing attention. Since the advent of Industry 4.0, CPS has been actively studied in fields such as smart factories and vehicle networks. CPS is tight integration of cyber space and physical space through networking. Therefore, the design of a network that connects cyber space and physical space takes a large portion in the importance of CPS research. As CPS can be expressed in various types of systems, it is necessary to design various networks accordingly. This dissertation focuses on the wireless networked control system among CPS. However, there are various types of wireless networked control system, and since the network and physical systems in wireless network control system are mutually interacted, a network and control co-design is required, not network design. In this dissertation, we propose the network and control co-design of CPS that considers the following three situations: (i) wireless channel uncertainty, (ii) heterogeneous sampling rates, and (iii) hierarchical networked control system.
Table Of Contents
1 Introduction 1 1.1 Background and Problems Addressed 1 1.2 Outline of Dissertation 2 2 Networked Control Systems for Cyber-Physical Systems 5 3 Resilient Architecture for Network and Control Co-Design under Wireless Channel Uncertainty 7 3.1 Introduction 7 3.2 Motivation: What Happens to Control Performance under Wireless Channel Uncertainty? 9 3.3 Problem Formulation 11 3.3.1 Conventional Network and Control Co-Design 11 3.3.2 Network and Control Co-Design with Rate Adaptation 15 3.4 W-Simplex: Resilient Architecture for Network and Control Co-Design 16 3.4.1 Wireless-Simplex (W-Simplex): Network and Control Co-Design against Wireless Channel Uncertainty 16 3.4.2 Control Cost 18 3.4.3 Network Delay Model 23 3.4.4 Network Performance Objective 28 3.5 Performance Evaluation 28 3.5.1 Simulation Setup 28 3.5.2 Control Performance under Uncertain Wireless Channel 30 3.6 Related Work 34 3.7 Conclusion 37 4 Sampling Rate Optimization for IEEE 802.11 Wireless Control Systems 41 4.1 Introduction 41 4.2 Related Work 43 4.3 Problem formulation 45 4.3.1 System Model 45 4.3.2 Network and Control Co-Design 47 4.3.3 Convex Relaxation 50 4.4 Performance Evaluation 54 4.4.1 Testbed 54 4.4.2 Simulation Study 56 4.4.3 Experiments 60 4.5 Conclusions and Future Work 63 5 Network and Control Co-Design for Large-Scale Cyber-Physical Systems 65 5.1 Introduction 65 5.2 Problem formulation 66 5.2.1 System description 66 5.2.2 System model 68 5.2.3 Network and Control Co-Design 69 5.3 Validation Experiments 75 5.3.1 Testbed 75 5.3.2 Local Network 78 5.4 Conclusions and Future Work 83 6 Conclusions of Dissertation 93 국문초록 102