Trustworthy Cyber Physical Systems

Abstract

Systems that involve a tight integration of models of physical entities (such as their dynamics), algorithms for controlling them, and computational platforms for implementing these algorithms, are referred to as cyber-physical systems (CPS). Traditionally, control theory or the development of control algorithms, and hardware/software techniques for implementing these algorithms were studied and developed independently by disjoint communities - control theorists on one hand, and embedded systems and software engineers on the other hand. But as embedded platforms become more complex and distributed, this isolated development of the two areas - control algorithm design and control algorithm implementation - is leading to significant integration, testing and debugging costs. This is because assumptions made during the design phase - like negligible time needed to compute the control law, zero-delays between the sensors and controllers and controllers and actuators, availability of infinite numerical precision when computing control inputs, etc. - do not hold during the implementation phase. This leads to a deviation in the expected control performance at the design phase, and what is realized after implementation.In order to address this, CPS-oriented design methods involve a co-design of the control algorithms and hardware/software platforms for implementing these algorithms. Towards this, this tutorial will discuss cross-layer techniques for designing embedded control systems. These layers include control models to code synthesis, and code to implementations on distributed architectures where we will talk about computation, communication and memory-aware design of control systems. Finally, the tutorial will also discuss how reliability issues of modern semiconductor devices may be accounted for during the control design phase. Such a cross-layer design - starting from models of physical systems, to software, to architecture, and finally to reliability of circuits and devices - will result in certifiable and trustworthy cyber-physical systems for which end-to-end guarantees may be offered. The application domains where these techniques may be applied are varied and range over automotive, avionics, industrial automation, and medical technology.Currently there is a tremendous amount of interest in cyber-physical systems. However, this is an interdisciplinary topic involving the intersection of control theory, communications, embedded systems, and embedded software. This tutorial will introduce to an audience with a primarily embedded systems background the opportunities that exist at the intersection of control theory and embedded systems & software - which constitutes the core of cyber-physical systems. Since we will cover all the layers of the design stack - from high-level models, to software, architecture, and then circuits and devices - the tutorial will also highlight verification challenges at all these layers, along with how modeling and analysis techniques from each of these layers may be composed to built certifiable and trustworthy systems. The tutorial will provide enough background to researchers and doctoral candidates - who are new to the topic of CPS - to be able to start exploring problems in this domain. It will also provide a variety of examples that will help practitioners from the industry.