An introduction to event-triggered and self-triggered control

Abstract

Abstract-Recent developments in computer and communication technologies have led to a new type of large-scale resource-constrained wireless embedded control systems. It is desirable in these systems to limit the sensor and control computation and/or communication to instances when the system needs attention. However, classical sampled-data control is based on performing sensing and actuation periodically rather than when the system needs attention. This paper provides an introduction to event-and self-triggered control systems where sensing and actuation is performed when needed. Eventtriggered control is reactive and generates sensor sampling and control actuation when, for instance, the plant state deviates more than a certain threshold from a desired value. Selftriggered control, on the other hand, is proactive and computes the next sampling or actuation instance ahead of time. The basics of these control strategies are introduced together with a discussion on the differences between state feedback and output feedback for event-triggered control. It is also shown how event-and self-triggered control can be implemented using existing wireless communication technology. Some applications to wireless control in process industry are discussed as well.

Input-to-state stabilizing event-triggered control for linear systems with output quantization

“…Property (2) means that an ISS with respect to w is guaranteed for the set A whose size depends on ∆ 0 . This is due to the fact that µ does not eventually go to 0 since we stop zooming-in when µ < ∆0 ℓin according to (9), which is also the case in, e.g., [11], [12]. Property (3) means that chatteringlike behaviour between the zoom-in and the zoom-out stages does not occur.…”

“…In this regard, event-triggered controllers have shown more potential to achieve this goal than time-triggered setups. The idea of this technique is to allow the network access only when it is needed, from the stability/performance perspectives, see, e.g., [9] and the references therein. This consequently allows to save the network from unnecessary usages, however, more difficulties are induced on the stability analysis.…”

Reducing usage of the computational resources by event driven approach to model predictive control

“…Also an on-line approach for improving performance of the off-line control and resource schedule, called Optimal Pointer Placement , is presented in this work. Interesting approaches can also be found in the literature dealing with the networked control systems (NCS), two main approaches oriented towards achieving resource utilization reduction (to save computation and communication resources) can be distinguished, namely, Event-Triggered Control (ETC) and Self-Triggered Control (STC) [5,6]. The control law in ETC and STC consists of a feedback controller that computes the control signals, and a triggering mechanism that determines when the control signals have to be updated.…”

Self-Triggered and Event-Triggered Set-Valued Observers

“…An event-triggered solution results in a more informed choice, since the sensor has access to the actual measurement, but prevents the sensor from being shut down between updates. For a recent discussion on event-and self-triggered control and estimation, the reader is referred to [15].…”

“…In [3] and [4], Kalman-like filters are proposed for state estimation, thus not providing a deterministic bound for the error. For event-triggered systems, a triggering condition can be posed on the norm of the estimation error being below a given threshold, dependent on the norm of the state [19] [2]; requiring the derivative of a Lyapunov function of the state being semi-negative definite [15], [18]; or, having the norm of the state below a certain threshold [14].…”