Resource and performance trade-offs in real-time embedded control systems

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Resource and performance trade-offs in real-time embedded control systems Camilo Lozoya · Pau Martí · Manel Velasco · Josep M. Fuertes · Enrix X. Martin

Published online: 28 December 2012 © Springer Science+Business Media New York 2012

Abstract Embedded control systems are subject to conflicting demands: end-users ask for devices with better capabilities while strong industrial competition impose tight cost constrains that results in devices with limited resources. Current research in the multidisciplinary embedded systems discipline indicates that by combining realtime and control systems it is theoretically feasible to design resource-constrained embedded control systems capable of trading-off control performance and resource usage. This paper focuses on the implementation feasibility of recent state-of-the-art resource/performance-aware (RPA) policies that can be applied to a set of control loops that concurrently execute on a microprocessor. The objective of these policies is to improve control performance and/or to minimize resource utilization. The paper first reviews existing state-of-the-art RPA policies. Then it presents a performance evaluation framework (PEF) that permits to assess whether RPA policies can be implemented in practice. The PEF is designed using a modular approach and following the guidelines obtained by a taxonomic analysis performed on the state-of-the-art RPA policies. Finally, a case study is presented where the PEF is applied to a set of representative RPA policies. The case study reveals that the modularity of the PEF C. Lozoya · P. Martí () · M. Velasco · J.M. Fuertes · E.X. Martin Automatic Control Department, Technical University of Catalonia, Pau Gargallo 5, 08028 Barcelona, Spain e-mail: [email protected] C. Lozoya e-mail: [email protected] M. Velasco e-mail: [email protected] J.M. Fuertes e-mail: [email protected] E.X. Martin e-mail: [email protected]

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Real-Time Syst (2013) 49:267–307

allows tailoring the framework to evaluate any specific RPA policy, which indicates that RPA policies can be implemented in practice. But it also reveals that the problem of assessing diverse RPA policies in fair conditions implies facing and solving conflicting demands by even taking decisions that may not favor equal all policies under evaluation. Nevertheless, the comparative analysis permits identifying potential benefits and drawbacks of each policy, as well as extracting design guidelines for future real-time embedded control systems theory and practice. Keywords Embedded control systems · Resource utilization · Control performance

1 Introduction Embedded devices are being widely used in many areas, playing a key role in our society. An embedded system is a special-purpose computer system designed to perform dedicated control activities, interacting with the environment. Currently 98 % of computing devices in the world are embedded systems. Conservative estimations indicate a forecast of over 40 billion of available embedded devices worldwide by 2020 (Artemis