Attack-Resilient Supervisory Control of Discrete-Event Systems

In this work, we study the problem of supervisory control of discrete-event systems (DES) in the presence of attacks that tamper with inputs and outputs of the plant. We consider a very general system setup as we focus on both deterministic and nondeterministic plants that we model as finite state transducers (FSTs); this also covers the conventional approach to modeling DES as deterministic finite automata. Furthermore, we cover a wide class of attacks that can nondeterministically add, remove, or rewrite a sensing and/or actuation word to any word from predefined regular languages, and show how such attacks can be modeled by nondeterministic FSTs; we also present how the use of FSTs facilitates modeling realistic (and very complex) attacks, as well as provides the foundation for design of attack-resilient supervisory controllers. Specifically, we first consider the supervisory control problem for deterministic plants with attacks (i) only on their sensors, (ii) only on their actuators, and (iii) both on their sensors and actuators. For each case, we develop new conditions for controllability in the presence of attacks, as well as synthesizing algorithms to obtain FST-based description of such attack-resilient supervisors. A derived resilient controller provides a set of all safe control words that can keep the plant work desirably even in the presence of corrupted observation and/or if the control words are subjected to actuation attacks. Then, we extend the controllability theorems and the supervisor synthesizing algorithms to nondeterministic plants that satisfy a nonblocking condition. Finally, we illustrate applicability of our methodology on several examples and numerical case-studies

Constructivist Multi-Access Lab Approach in Teaching FPGA Systems Design with LabVIEW

Embedded systems play vital role in modern applications [1]. They can be found in autos, washing machines, electrical appliances and even in toys. FPGAs are the most recent computing technology that is used in embedded systems. There is an increasing demand on FPGA based embedded systems, in particular, for applications that require rapid time responses. Engineering education curricula needs to respond to the increasing industrial demand of using FPGAs by introducing new syllabus for teaching and learning this subject. This paper describes the development of new course material for teaching FPGA-based embedded systems design by using ‘G’ Programming Language of LabVIEW. A general overview of FPGA role in engineering education is provided. A survey of available Hardware Programming Languages for FPGAs is presented. A survey about LabVIEW utilization in engineering education is investigated; this is followed by a motivation section of why to use LabVIEW graphical programming in teaching and its capabilities. Then, a section of choosing a suitable kit for the course is laid down. Later, constructivist closed-loop model the FPGA course has been proposed in accordance with [2- 4; 80,86,89,92]. The paper is proposing a pedagogical framework for FPGA teaching; pedagogical evaluation will be conducted in future studies. The complete study has been done at the Faculty of Electrical and Electronic Engineering, Aleppo University

Task Migration for Fault-Tolerance in Mixed-Criticality Embedded Systems

In this paper we are interested in mixed-criticality embed-ded applications implemented on distributed architectures. Depending on their time-criticality, tasks can be hard or soft real-time and regarding safety-criticality, tasks can be fault-tolerant to transient faults, permanent faults, or have no dependability requirements. We use Earliest Deadline First (EDF) scheduling for the hard tasks and the Constant Bandwidth Server (CBS) for the soft tasks. The CBS pa-rameters determine the quality of service (QoS) of soft tasks. Transient faults are tolerated using checkpointing with roll-back recovery. For tolerating permanent faults in proces-sors, we use task migration, i.e., restarting the safety-critical tasks on other processors. We propose a Greedy-based on-line heuristic for the migration of safety-critical tasks, in response to permanent faults, and the adjustment of CBS parameters on the target processors, such that the faults are tolerated, the deadlines for the hard real-time tasks are sat-isfied and the QoS for soft tasks is maximized. The proposed online adaptive approach has been evaluated using several synthetic benchmarks and a real-life case study. 1