Research On Resource Optimization In Wireless Networked Control Systems

With the rapid progress of wireless communication, wireless sensor node and microelectronics technologies in recent years, wireless networked control system (WNCS) which is evolved from wireless sensor networks (WSN) and networked control system (NCS), is arising. WNCS is an interdiscipline involved with communication technology, network technology, computing technol-ogy, control theorem and etc. It has been widely applied in various applications, such as industrial processes, environmental monitoring, agricultural applications, Cyber-physical systems (CPS) and smart grid. It has gained great attentions of global researchers for the convenience that it brings to the productivities and lives of human beings.Resource optimization is one of the fundamental topics in WNCS, and the interaction between network communication and close-loop control makes it a challenging problem. Most of existing works on the resource optimization in WNCS focus on one aspect among network communication, estimation or close-loop control performance. Nevertheless, the cooperative optimization of the above three aspects remain to be perfected. In this thesis, based on the latest results, the interaction between network communication, estimation and control is considered, and the cooperative opti-mization of them is studied in detail. The main work and contribution are summarized as follows.1. A brief literature review on WNCS and related works is provided.2. For the remote state estimation problem with wireless channel interference, under the real wireless communication model, a sensor transmission schedule is proposed based on Model Predictive Control (MPC) method. In particular, a two-sensor case is studied in detail and the analytical transmission schedule is developed, whose effectiveness is verified by theoretical analysis and numerical results.3. For the remote state estimation problem in multi-hop wireless communication, an energy-efficient data forwarding strategy is proposed. Firstly, two basic data forwarding strategies named Direct Forwarding Strategy (DFS) and Local process and Forwarding Strategy (LFS) are proposed, and then their estimation performance and energy cost are compared. Sec-ondly, to take the advantages of the above two strategies, a novel Event-triggered Forwarding Strategy (EFS) is developed, which is shown to achieve satisfactory estimation performance with low energy cost.4. The optimal controller location problem in WNCS is studied. With the consideration of random packet loss in both sensor-to-controller channel and controller-to-actuator channel, the close-loop control performance is formulated as a function of the packet reception rates of the two channels. Then the optimal controller location is then solved for both scalar system and vector system.5. For multi-target localization problem in WNCS, a sensor activation algorithm is proposed. Compressive Sampling (CS) is using in multi-target localization. In every time step, an it-erative activation algorithm is run on each sensor node based on the last localization results, which will make the particular sensor nodes with larger SNR be activated with higher prob-ability to measure the signals from targets. This will optimize the use of sensor energy in WNCS. Then the IA-LSCS algorithm is proposed to further improve the localization accu-racy, which is shown to be well applied in tracking mobile targets.In the end, the thesis is concluded and some future research works are discussed.