Sokolsky, Oleg

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Now showing 1 - 8 of 8
  • Publication
    Towards Assurance Cases for Resilient Control Systems
    (2014-08-01) Weimer, James; Sokolsky, Oleg; Bezzo, Nicola; Lee, Insup
    The paper studies the problem of constructing assurance cases for embedded control systems developed using a model-based approach. Assurance cases aim to provide a convincing argument that the system delivers certain guarantees, based on the evidence obtained during the design and evaluation of the system. We suggest an argument strategy centered around properties of models used in the development and properties of tools that manipulate these models. The paper presents the case study of a resilient speed estimator for an autonomous ground vehicle and takes the reader through a detailed assurance case arguing that the estimator computes speed estimates with bounded error.
  • Publication
    A Safety Case Pattern for Model-Based Development Approach
    (2012-04-01) Ayoub, Anaheed; Kim, BaekGyu; Lee, Insup; Sokolsky, Oleg
    In this paper, a safety case pattern is introduced to facilitate the presentation of a correctness argument for a system implemented using formal methods in the development process. We took advantage of our experience in constructing a safety case for the Patient Controlled Analgesic (PCA) infusion pump, to define this safety case pattern. The proposed pattern is appropriate to be instantiated within the safety cases constructed for systems that are developed by applying model-based approaches.
  • Publication
    An Intraoperative Glucose Control Benchmark for Formal Verification
    (2015-10-01) Chen, Sanjian; O'Kelly, Matthew; Weimer, James; Sokolsky, Oleg; Lee, Insup
    Diabetes associated complications are affecting an increasingly large population of hospitalized patients. Since glucose physiology is significantly impacted by patient-specific parameters, it is critical to verify that a clinical glucose control protocol is safe across a wide patient population. A safe protocol should not drive the glucose level into dangerous low (hypoglycemia) or high (hyperglycemia) ranges. Verification of glucose controllers is challenging due to the high-dimensional, non-linear glucose physiological models which contain both unobservable states and unmeasurable patient-specific parameters. This paper presents a hybrid system model of a closed-loop physiological system that includes an existing FDA-accepted high-fidelity physiological model tailored to intraoperative settings and a validated improvement to a clinical glucose control protocol for diabetic cardiac surgery patients. We propose the closed-loop model as a physiological system benchmark for verification and present our initial results on verifying the system using the SMT-based hybrid system verification tool dReach.
  • Publication
    Permission to Speak: A Logic for Access Control and Conformance
    (2010-01-01) Dinesh, Nikhil; Joshi, Aravind; Lee, Insup; Sokolsky, Oleg
    Formal languages for policy have been developed for access control and conformance checking. In this paper, we describe a formalism that combines features that have been developed for each application. From access control, we adopt the use of a saying operator. From conformance checking, we adopt the use of operators for obligation and permission. The operators are combined using an axiom that permits a principal to speak on behalf of another. The combination yields benefits to both applications. For access control, we overcome the problematic interaction between hand-off and classical reasoning. For conformance, we obtain a characterization of legal power by nesting saying with obligation and permission. The axioms result in a decidable logic. We integrate the axioms into a logic programming approach, which lets us use quantification in policies while preserving decidability of access control decisions. Conformance checking, in the presence of nested obligations and permissions, is shown to be decidable. Non-interference is characterized using reachability via permitted statements.
  • Publication
    GSA: A Framework for Rapid Prototyping of Smart Alarm Systems
    (2010-11-11) King, Andrew; Roederer, Alex; Arney, David; Chen, Sanjian; Fortino-Mullen, Margaret; Giannareas, Ana; Hanson III, C. William; Kern, Vanessa; Stevens, Nicholas; Viesca Trevino, Adrian; Park, Soojin; Sokolsky, Oleg; Lee, Insup; Tannen, Jonathan
    We describe the Generic Smart Alarm, an architectural framework for the development of decision support modules for a variety of clinical applications. The need to quickly process patient vital signs and detect patient health events arises in many clinical scenarios, from clinical decision support to tele-health systems to home-care applications. The events detected during monitoring can be used as caregiver alarms, as triggers for further downstream processing or logging, or as discrete inputs to decision support systems or physiological closed-loop applications. We believe that all of these scenarios are similar, and share a common framework of design. In attempting to solve a particular instance of the problem, that of device alarm fatigue due to numerous false alarms, we devised a modular system based around this framework. This modular design allows us to easily customize the framework to address the specific needs of the various applications, and at the same time enables us to perform checking of consistency of the system. In the paper we discuss potential specific clinical applications of a generic smart alarm framework, present the proposed architecture of such a framework, and motivate the benefits of a generic framework for the development of new smart alarm or clinical decision support systems.
  • Publication
    The Medical Device Dongle: An Open-Source Standards-Based Platform for Interoperable Medical Device Connectivity
    (2012-01-28) Asare, Philip; Cong, Danyang; Vattam, Santosh G.; Kim, BaekGyu; King, Andrew; Sokolsky, Oleg; Lee, Insup; Lin, Shan; Mullen-Fortino, Margaret
    Emerging medical applications require device coordination, increasing the need to connect devices in an interoperable manner. However, many of the existing health devices in use were not originally developed for network connectivity and those devices with networking capabilities either use proprietary protocols or implementations of standard protocols that are unavailable to the end user. The first set of devices are unsuitable for device coordination applications and the second set are unsuitable for research in medical device interoperability. We propose the Medical Device Dongle (MDD), a low-cost, open-source platform that addresses both issues.
  • Publication
    Architecture-Centric Software Development for Cyber-Physical Systems
    (2014-10-01) Sokolsky, Oleg; Pajic, Miroslav; Bezzo, Nicola; Lee, Insup
    We discuss the problem of high-assurance development of cyber-physical systems. Specifically, we concentrate on the interaction between the development of the control system layer and platform-specific software engineering for system components. We argue that an architecture-centric approach allows us to streamline the development and increase the level of assurance for the resulting system. The case study of an unmanned ground vehicle illustrates the approach.
  • Publication
    A Systematic Approach to Justifying Sufficient Confidence in Software Safety Arguments
    (2012-06-15) Ayoub, Anaheed; Kim, Baekgyu; Lee, Insup; Sokolsky, Oleg
    Safety arguments typically have some weaknesses. To show that the overall confidence in the safety argument is considered acceptable, it is necessary to identify the weaknesses associated with the aspects of a safety argument and supporting evidence, and manage them. Confidence arguments are built to show the existence of sufficient confidence in the developed safety arguments. In this paper, we propose an approach to systematically constructing confidence arguments and identifying the weaknesses of the software safety arguments. The proposed approach is described and illustrated with a running example.