A Map-Reduce Parallel Approach to Automatic Synthesis of Control Software

Many Control Systems are indeed Software Based Control Systems, i.e. control systems whose controller consists of control software running on a microcontroller device. This motivates investigation on Formal Model Based Design approaches for automatic synthesis of control software. Available algorithms and tools (e.g., QKS) may require weeks or even months of computation to synthesize control software for large-size systems. This motivates search for parallel algorithms for control software synthesis. In this paper, we present a Map-Reduce style parallel algorithm for control software synthesis when the controlled system (plant) is modeled as discrete time linear hybrid system. Furthermore we present an MPI-based implementation PQKS of our algorithm. To the best of our knowledge, this is the first parallel approach for control software synthesis. We experimentally show effectiveness of PQKS on two classical control synthesis problems: the inverted pendulum and the multi-input buck DC/DC converter. Experiments show that PQKS efficiency is above 65%. As an example, PQKS requires about 16 hours to complete the synthesis of control software for the pendulum on a cluster with 60 processors, instead of the 25 days needed by the sequential algorithm in QKS.Comment: To be submitted to TACAS 2013. arXiv admin note: substantial text overlap with arXiv:1207.4474, arXiv:1207.409

Memory Resilient Gain-scheduled State-Feedback Control of Uncertain LTI/LPV Systems with Time-Varying Delays

The stabilization of uncertain LTI/LPV time delay systems with time varying delays by state-feedback controllers is addressed. At the difference of other works in the literature, the proposed approach allows for the synthesis of resilient controllers with respect to uncertainties on the implemented delay. It is emphasized that such controllers unify memoryless and exact-memory controllers usually considered in the literature. The solutions to the stability and stabilization problems are expressed in terms of LMIs which allow to check the stability of the closed-loop system for a given bound on the knowledge error and even optimize the uncertainty radius under some performance constraints; in this paper, the $\mathcal{H}_\infty$ performance measure is considered. The interest of the approach is finally illustrated through several examples

Embedding the concept of ecosystems services:The utilisation of ecological knowledge in different policy venues

The concept of ecosystem services is increasingly being promoted by academics and policy makers as a means to protect ecological systems through more informed decision making. A basic premise of this approach is that strengthening the ecological knowledge base will significantly enhance ecosystem health through more sensitive decision making. However, the existing literature on knowledge utilisation, and many previous attempts to improve decision making through better knowledge integration, suggest that producing ‘more knowledge’ is only ever a necessary but insufficient condition for greater policy success. We begin this paper by reviewing what is already known about the relationship between ecological knowledge development and utilisation, before introducing a set of theme issue papers that examine—for the very first time—how this politically and scientifically salient relationship plays out across a number of vital policy venues such as land-use planning, policy-level impact assessment, and cost–benefit analysis. Following a detailed synthesis of the key findings of all the papers, this paper identifies and explores new research and policy challenges in this important and dynamic area of environmental governance

Optimization techniques with knowledge based control in ship concept design

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.An integrated computational approach to Ship Concept Design using optimization techniques and a knowledge base to control the optimization process has been developed. The system automates both synthesis and analysis; analysis by the repeated sequential use of Design Theory Modules and synthesis through the optimization process, which compromises conflicting requirements, subject to constraints. The intention of this work has been to find a better approach to automated design synthesis and at the same time employ detailed analytical tools such as a three-dimensional hull-form definition and engineering analysis modules. Optimization techniques and a knowledge base are combined to achieve the desired capabilities, taking advantage of the benefits optimization can bring using goal oriented methods and exploratory searches, alongside a knowledge base that controls the synthesis process rather than the design. A function mapping strategy has been developed to provide a multiple-parametric view of regions of the optimization objective function and constraints. A discussion is included on the role of further applications of expert systems to design systems in both synthesis and analysis and their possible interference with creativity and innovation. Two design examples are provided, one showing the application of the system using optimization and the other adding the use of the knowledge base. The results are compared and discussed.National Council of Research (CNPq - Brazil

Barrier-Based Test Synthesis for Safety-Critical Systems Subject to Timed Reach-Avoid Specifications

We propose an adversarial, time-varying test-synthesis procedure for safety-critical systems without requiring specific knowledge of the underlying controller steering the system. From a broader test and evaluation context, determination of difficult tests of system behavior is important as these tests would elucidate problematic system phenomena before these mistakes can engender problematic outcomes, e.g. loss of human life in autonomous cars, costly failures for airplane systems, etc. Our approach builds on existing, simulation-based work in the test and evaluation literature by offering a controller-agnostic test-synthesis procedure that provides a series of benchmark tests with which to determine controller reliability. To achieve this, our approach codifies the system objective as a timed reach-avoid specification. Then, by coupling control barrier functions with this class of specifications, we construct an instantaneous difficulty metric whose minimizer corresponds to the most difficult test at that system state. We use this instantaneous difficulty metric in a game-theoretic fashion, to produce an adversarial, time-varying test-synthesis procedure that does not require specific knowledge of the system's controller, but can still provably identify realizable and maximally difficult tests of system behavior. Finally, we develop this test-synthesis procedure for both continuous and discrete-time systems and showcase our test-synthesis procedure on simulated and hardware examples

Neuromorphic analogue VLSI

Neuromorphic systems emulate the organization and function of nervous systems. They are usually composed of analogue electronic circuits that are fabricated in the complementary metal-oxide-semiconductor (CMOS) medium using very large-scale integration (VLSI) technology. However, these neuromorphic systems are not another kind of digital computer in which abstract neural networks are simulated symbolically in terms of their mathematical behavior. Instead, they directly embody, in the physics of their CMOS circuits, analogues of the physical processes that underlie the computations of neural systems. The significance of neuromorphic systems is that they offer a method of exploring neural computation in a medium whose physical behavior is analogous to that of biological nervous systems and that operates in real time irrespective of size. The implications of this approach are both scientific and practical. The study of neuromorphic systems provides a bridge between levels of understanding. For example, it provides a link between the physical processes of neurons and their computational significance. In addition, the synthesis of neuromorphic systems transposes our knowledge of neuroscience into practical devices that can interact directly with the real world in the same way that biological nervous systems do

Using domain specific languages to capture design knowledge for model-based systems engineering

Design synthesis is a fundamental engineering task that involves the creation of structure from a desired functional specification; it involves both creating a system topology as well as sizing the system's components. Although the use of computer tools is common throughout the design process, design synthesis is often a task left to the designer. At the synthesis stage of the design process, designers have an extensive choice of design alternatives that need to be considered and evaluated. Designers can benefit from computational synthesis methods in the creative phase of the design process. Recent increases in computational power allow automated synthesis methods for rapidly generating a large number of design solutions. Combining an automated synthesis method with an evaluation framework allows for a more thorough exploration of the design space as well as for a reduction of the time and cost needed to design a system. To facilitate computational synthesis, knowledge about feasible system configurations must be captured. Since it is difficult to capture such synthesis knowledge about any possible system, a design domain must be chosen. In this thesis, the design domain is hydraulic systems. In this thesis, Model-Driven Software Development concepts are leveraged to create a framework to automate the synthesis of hydraulic systems will be presented and demonstrated. This includes the presentation of a domain specific language to describe the function and structure of hydraulic systems as well as a framework for synthesizing hydraulic systems using graph grammars to generate system topologies. Also, a method using graph grammars for generating analysis models from the described structural system representations is presented. This approach fits in the context of Model-Based Systems Engineering where a variety of formal models are used to represent knowledge about a system. It uses the Systems Modeling Language developed by The Object Management Group (OMG SysML™) as a unifying language for model definition.M.S.Committee Chair: Paredis, Chris; Committee Member: McGinnis, Leon; Committee Member: Schaefer, Dir

Game-based Synthesis of Distributed Controllers for Sampled Switched Systems

Switched systems are a convenient formalism for modeling physical processes interacting with a digital controller. Unfortunately, the formalism does not capture the distributed nature encountered e.g. in cyber-physical systems, which are organized as networks of elements interacting with local controllers. Most current methods for control synthesis can only produce a centralized controller, which is assumed to have complete knowledge of all the component states and can interact with all of them. In this paper, we consider a centralized-controller synthesis technique based on state-space decomposition, and use a game-based approach to extend it to a distributed framework

Revisiting the Status of Speech Rhythm

Text-to-Speech synthesis offers an interesting manner of synthesising various knowledge components related to speech production. To a certain extent, it provides a new way of testing the coherence of our understanding of speech production in a highly systematic manner. For example, speech rhythm and temporal organisation of speech have to be well-captured in order to mimic a speaker correctly. The simulation approach used in our laboratory for two languages supports our original hypothesis of multidimensionality and non-linearity in the production of speech rhythm. This paper presents an overview of our approach towards this issue, as it has been developed over the last years. We conceive the production of speech rhythm as a multidimensional task, and the temporal organisation of speech as a key component of this task (i.e., the establishment of temporal boundaries and durations). As a result of this multidimensionality, text-to-speech systems have to accommodate a number of systematic transformations and computations at various levels. Our model of the temporal organisation of read speech in French and German emerges from a combination of quantitative and qualitative parameters, organised according to psycholinguistic and linguistic structures. (An ideal speech synthesiser would also take into account subphonemic as well as pragmatic parameters. However such systems are not yet available)