Resource-aware control and dynamic scheduling in CPS

\u3cp\u3eRecent developments in computer and communication technologies are leading to an increasingly networked and wireless world. This raises new challenging questions in the context of control for cyberphysical systems (CPS), especially when the computation, communication, energy and actuation resources (for control) of the system are limited and/or shared by multiple control tasks. These limitations obstruct the use of classical design techniques for feedback control algorithms and call for new resource-aware control paradigms. These new resource-aware control systems typically have to take both discrete decisions (which task is allowed to use the resource) and continuous decisions (which continuous control input is generated for the task). In this talk two approaches are presented to address this hybrid co-design problem. Both approaches result in control algorithms that exploit real-time measurement information available on the state of the CPS and decide dynamically on the actions to take. This leads to the situation that individual control tasks are no longer executed in classical periodic time-triggered patterns, but in aperiodic patterns with varying inter-execution times. By abandoning the periodic scheduling of control tasks, the aim is to realise better trade-offs between the overall performance of the CPS and the required resource utilisation. The approaches are illustrated by various applications. interesting challenges for the future are discussed as well.\u3c/p\u3

Positive polynomials and control applications

Literature Research

Model-based tracking control of a Rovio TM mobile robot

No abstract

Survey on network control system software tools

Internship project

Event-triggered control systems under packet losses

\u3cp\u3eNetworked control systems (NCSs) offer many benefits in terms of increased flexibility and maintainability but might also suffer from inevitable imperfections such as packet dropouts and limited communications resources. In this paper, (static and dynamic) event-triggered control (ETC) strategies are proposed that aim at reducing the utilization of communication resources while guaranteeing desired stability and performance criteria and a strictly positive lower bound on the inter-event times despite the presence of packet losses. For the packet losses, we consider both configurations with an acknowledgement scheme (as, e.g., in the transmission control protocol (TCP)) and without an acknowledgement scheme (as, e.g., in the user diagram protocol (UDP)). The proposed design methodology will be illustrated by means of a numerical example which reveals tradeoffs between the maximum allowable number of successive packet dropouts, (minimum and average) inter-event times and L\u3csub\u3ep\u3c/sub\u3e-gains of the closed-loop NCS.\u3c/p\u3

Dynamic event-Triggered control under packet losses:The case with acknowledgements

\u3cp\u3eIn this paper, a dynamic ETC strategy for nonlinear state-feedback systems is proposed that results in guarantees for a finite ℓ\u3csub\u3ep\u3c/sub\u3e-gain from disturbance input to performance output and a strictly positive lower bound on the inter-event times despite the presence of packet losses. The proposed dynamic ETC strategy has several advantages with respect to the commonly studied static ETC strategy including significantly larger average inter-event times. The proposed design methodology results in tradeoffs between the maximum allowable number of successive packet dropouts, (minimum and average) inter-event times and ℓ\u3csub\u3ep\u3c/sub\u3e-gains, which will be illustrated by means of a numerical example.\u3c/p\u3

Optimized input-to-state stabilization of discrete-time nonlinear systems with bounded inputs

In the problem of input-to-state stabilization of nonlinear systems, synthesis of input-to-state stabilizing feedback laws is usually carried out off-line. This results in a constant input-to-state stability (ISS) gain, which is guaranteed for the closed-loop system. As an alternative, we propose a finite dimensional optimization problem that allows for the simultaneous on-line computation of an ISS control action, and minimization of the ISS gain of the closed-loop system. The advantages of the developed controller are: ISS is guaranteed for any (feasible) solution of the optimization problem, constraints can be explicitly accounted for and feedback to disturbances is provided actively, on-line. The control scheme also has favorable computational properties for nonlinear systems affine in control. In this case the optimization problem can be formulated as a single quadratic or linear progra