Suboptimal event‐triggered control for networked control systems

Abstract

Key words Networked control systems, control over packet-switched communications, event-triggered control, stochastic optimal control, long-run average cost optimization, stochastic stability, drift criteria.The advent of networked control systems urges the digital control design to incorporate communication constraints efficiently. In order to accommodate this requirement, this article studies the joint design of controller and event-trigger for linear stochastic systems in the presence of a resource-limited communication channel which exhibits packet dropouts and time-delay. The event-trigger situated at the sensor decides at every sampling instance, whether to send information over the communication channel to the controller. The design approach is formulated as a stochastic average-cost optimization problem, where the communication constraints are reflected as an additional cost penalty of the average transmission rate. Different conditions on the communication model are given where the joint optimal design can be split into a separate control and event-trigger design. Based on these results, two suboptimal design approaches are developed. By using drift criteria, stability guarantees of the closed-loop system for both approaches are derived in terms of bounded moment stability. Numerical simulations illustrate the efficacy of the event-triggered approach compared with optimal time-triggered controllers.

Event-Triggered Control for String-Stable Vehicle Platooning

“…In this paper, we consider event-triggered control (ETC) schemes that determine the transmission instants by means of a triggering condition that depends on locally available output measurements, see, e.g., [2], [7], [11], [12], [14], [33], [41], [47], [51] and the references therein for more details on ETC. In this way, the communication resources are only used when necessary to maintain desired closed-loop behavior and the utilization of communication resources is reduced.…”

Output‐based event‐triggered control of networked systems subject to bilateral packet dropouts

“…To investigate the influence of these challenges on system performance, the packet dropout behavior is described by a random variable with Bernoulli binary distribution 16 . For a discrete‐time linear system, an event trigger located at the sensor and the controller with data packet losses in the unilateral networks is designed 17 . For multiple systems sharing, a common wireless communication network, the design of event‐triggered control law and one‐side data packet loss behaviors are considered 18 .…”

“…16 For a discrete-time linear system, an event trigger located at the sensor and the controller with data packet losses in the unilateral networks is designed. 17 For multiple systems sharing, a common wireless communication network, the design of event-triggered control law and one-side data packet loss behaviors are considered. 18 Compared with unilateral networks, the bilateral NCSs relax restrictions on physical location and reduce the complexity of subsystems connections, which further improves the system integration and reduces the operation and maintenance costs.…”

Evaluation of novel self‐triggering method for optimisation of communication and control

“…As pointed out by Mahmoud and Memon [2], there are two methodologies to achieve simultaneous design of control and triggering mechanism in ET NCSs: cost function minimisation which penalises the inter-event times besides state and control variable [3][4][5][6], and Lyapunov approach [7][8][9]. Specifically, Demirel et al [3] presented a theoretical framework to analyse the trade-off between control performance and communication cost for transmission over a lossy network.…”

“…In [4], the certainty equivalence controller was reported to be optimal for ET control systems with some constraints. Two suboptimal design strategies for linear discrete-time (DT) stochastic systems with network imperfections were presented in [5]. To decouple communication from control in ET setting, Molin and Hirche [6] limited the usage of communication channel in terms of maximum allowable transmission rate.…”