Wireless networked control systems, as the name indicates, employ wireless networks to interconnect their components, e.g. sensors, computing units, and actuators, in their implementation. Removing wires from control system implementations, the components can be more easily installed in spatial positions that are hard to access, and facilitate their deployment within large physical scales. This enables the expansion of control applications to new domains or objectives previously not attainable. However, as a trade-off, in a wireless networked control system, the transmission bandwidth is much smaller compared to a wired one. Besides, to achieve flexibility and mobility, some nodes may have energy supplies from batteries, which have limited capacity and are usually costly to replace. The limitations in bandwidth and energy supplies is a major problem when designing wireless networked control systems. The purpose of this thesis is to study how to guarantee pre-designed stability and performance under limitations of bandwidth and energy supplies, with the goal to enrich the control approaches for resource-aware industrial applications.@en

Energy constraint long-range wireless sensor/actuator-based solutions are theoretically the perfect choice to support the next generation of city-scale cyber-physical systems. Traditional systems adopt periodic control which increases network congestion and actuations while burdens the energy consumption. Recent control theory studies overcome these problems by introducing aperiodic strategies, such as event-triggered control (ETC). In spite of the potential savings, these strategies assume actuator continuous listening, while ignoring the sensing energy costs. In this paper, we fill this gap, by enabling sensing and actuator listening duty cycling and proposing two innovative medium access control protocols for three decentralized ETC approaches. A laboratory experimental test bed, which emulates a smart water network, was modeled and extended to evaluate the impact of system parameters and the performance of each approach. Experimental results reveal the predominance of the decentralized ETC against the classic periodic control either in terms of communication or actuation by promising significant system lifetime extension.@en

Periodic event-triggered control (PETC) [13] is a version of event-triggered control that only requires the measurement of the plant output periodically instead of continuously. In this note, we present a construction of timing models for these PETC implementations to capture the dynamics of the traffic they generate. In the construction, we employ a two-step approach. We first partition the state space into a finite number of regions. Then, in each region, the event-triggering behavior is analyzed with the help of linear matrix inequalities. The state transitions among different regions result from computing the reachable state set starting from each region within the computed event time intervals.@en

Asynchronous decentralized event-triggered control (ADETC) Mazo Jr. and Cao (2014) is an implementation of controllers characterized by decentralized event generation, asynchronous sampling updates, and dynamic quantization. Combining those elements in ADETC results in a parsimonious transmission of information which makes it suitable for wireless networked implementations. We extend the previous work on ADETC by introducing periodic sampling, denoting our proposal asynchronous decentralized periodic event-triggered control (ADPETC), and study the stability and L2-gain of ADPETC for implementations affected by disturbances. In ADPETC, at each sampling time, quantized measurements from those sensors that triggered a local event are transmitted to a dynamic controller that computes control actions; the quantized control actions are then transmitted to the corresponding actuators only if certain events are also triggered for the corresponding actuator. The developed theory is demonstrated and illustrated via a numerical example.@en

Asynchronous event-triggered control (AETC) is a triggering strategy for the feedback channel of a closed-loop control system. AETC aims at reducing transmissions compared with time-triggered control strategies and listening time compared with other event-triggered control strategies. This work is an extension of the asynchronous event-triggered control [6] on reducing periodic listening time spent for the threshold update signal. In this work, by introducing an autonomous time-varying threshold update mechanism at every node, the listening time can totally be removed while still guaranteing a pre-designed control performance. A numerical example is shown to illustrate the developed strategy.@en

It has been shown in previous work that asynchronous event-triggered mechanisms can reduce measurement transmissions of control systems' implementations. In this paper we study the relation between minimum bandwidth of the feedback channels and the performance of linear systems. By using the S-procedure, the parameters in an asynchronous event-triggered implementation are optimized. Threshold update delays are considered, and two methods are presented to guarantee a certain performance under such delays. With the presented results, the implementations can be tuned to reduce the amount of communication rate while guaranteeing pre-specified performance levels. Simulation results are presented illustrating the applicability of this optimal asynchronous event-triggered implementation.@en

Asynchronous event-triggered control (AETC) is a control strategy proposed for wireless networked implementations whose sensor nodes have limited energy supplies. Local thresholds allow the sensors to sample and to transmit local measurements independently of each other. AETC uses only one bit for each measurement transmission while still guarantees stability and predesigned performance of the closed-loop. In this paper, we extend the previous work on AETC, and study the stability and L2-performance of periodic asynchronous event-triggered control (PAETC) for implementations with disturbances. In PAETC, the local event-triggered conditions are verified periodically at every sampling time. A dynamic controller is introduced to the PAETC framework, and the decision to transmit the controller outputs is also included in the asynchronous event-triggered mechanism to save network bandwidth. The developed theory is illustrated in a numerical example.@en