Daniel Lehmann

Distributed event-triggered control with network delays and packet losses

This paper presents a distributed event-based control approach to cope with communication delays and packet losses affecting a networked dynamical system consisting of N linear time-invariant coupled systems. Two communication protocols are proposed to deal with these communication effects. It is shown that both protocols preserve the system stability in the sense that the state of every subsystem converges to a small region around the origin if the delay and the number of packet losses are bounded. Analytical expressions for the delay bound and the maximum number of consecutive packet losses are derived. Simulations illustrate the results.

Event-triggered PI control subject to actuator saturation

Event-triggered control is a recent approach in control theory which aims at reducing the communication load in networked control systems by adapting the communication among the components to the c ...

Distributed event-triggered control for non-reliable networks

This paper presents a distributed event-based control approach to cope with communication delays and packet losses affecting a networked dynamical system. Two network protocols are proposed to deal with these communication effects. The stability of the system is analyzed for constant and time-dependent trigger functions, showing that asymptotic stability can be achieved with the latter design, and this also guarantees a lower bound for the inter-event times. Analytical expressions for the delay bound and the maximum number of consecutive packet losses are derived for different scenarios. Finally, the results are illustrated through a simulation example.

Event-triggered PI control: Saturating actuators and anti-windup compensation

Event-triggered control aims at reducing the communication load over the feedback link in networked control systems by adapting the information exchange to the current needs. This paper investigates the consequences of actuator saturation on the behavior of event-triggered PI control. Stability properties are derived using linear matrix inequalities (LMIs) which show how the stability of the event-triggered control loop depends on the selection of the event threshold. In order to overcome the potential performance degradation due to integrator windup caused by actuator saturation, the proposed scheme is extended by incorporating a static anti-windup mechanism. The results are illustrated by simulations.

Event-based control

Event-based control is a control methodology that is currently being developed as a means to reduce the communication between the sensors, the controller and the actuators in a control loop. The sampling instants are not determined periodically by a clock, but by an event generator, which adapts the information flow in the feedback loop to the current behavior of the closed-loop system. A communication among the components is invoked only after an event has indicated that the control error exceeds a tolerable bound.

Comparison between Sampled-Data Control, Deadband Control and Model-Based Event-Triggered Control

This paper investigates the stability as well as communication properties of sampleddata control and two event-triggered control schemes: deadband control and model-based eventtriggered control. Af ...

Two Complementary Approaches to Event-based Control (Zwei komplementäre Zugänge zur ereignisbasierten Regelung).

Abstract Event-based control aims at reducing the communication effort within a control loop by closing the feedback loop only if an event indicates e. g. a substantial control error. This paper proposes two new methods for event-based control that conjointly guarantee ultimate boundedness of the event-based control loop. The global approach faces the problem of driving a system from its initial state into a desired target set in the state space, whereas the local approach aims at keeping the system state within the target set. Both methods are experimentally evaluated by their application to a thermofluid process.

Reducing communication and actuation in distributed control systems

This paper addresses the problem of reducing the number of transmissions and control updates in a distributed control network of interconnected linear systems. Each node in the network decides when to transmit its state through the network and when to update the control law. Both decisions are event-driven and based on local information. It is shown that the stability of the system is preserved and the state of the system converges to a small region around the origin, whose size depends on the parameters of the transmission and control update trigger functions. A strictly positive lower bound for the inter-event times is derived. The results are illustrated through simulations showing the effectiveness of the proposed approach.

Distributed Event-Based Control for Non-reliable Networks

Even though event-based control has been shown to reduce the communication to face the problem of reduced bandwidth, network delays and packet losses can still occur in a distributed network. This chapter presents network protocols to deal with these problems and analyze the performance of different trigger functions in such scenario.