BaekGyu Kim

Challenges and Research Directions in Medical Cyber–Physical Systems

Medical cyber-physical systems (MCPS) are life-critical, context-aware, networked systems of medical devices. These systems are increasingly used in hospitals to provide high-quality continuous care for patients. The need to design complex MCPS that are both safe and effective has presented numerous challenges, including achieving high assurance in system software, intoperability, context-aware intelligence, autonomy, security and privacy, and device certifiability. In this paper, we discuss these challenges in developing MCPS, some of our work in addressing them, and several open research issues.

Safety-assured development of the GPCA infusion pump software

This paper presents our effort of using model-driven engineering to establish a safety-assured implementation of Patient-Controlled Analgesic (PCA) infusion pump software based on the generic PCA reference model provided by the U.S. Food and Drug Administration (FDA). The reference model was first translated into a network of timed automata using the UPPAAL tool. Its safety properties were then assured according to the set of generic safety requirements also provided by the FDA. Once the safety of the reference model was established, we applied the TIMES tool to automatically generate platform-independent code as its preliminary implementation. The code was then equipped with auxiliary facilities to interface with pump hardware and deployed onto a real PCA pump. Experiments show that the code worked correctly and effectively with the real pump. To assure that the code does not introduce any violation of the safety requirements, we also developed a testbed to check the consistency between the reference model and the code through conformance testing. Challenges encountered and lessons learned during our work are also discussed in this paper.

A safety case pattern for model-based development approach

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.

A systematic approach to justifying sufficient confidence in software safety arguments

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.

Demo of the medical device dongle: an open-source standards-based platform for interoperable medical device connectivity

Emerging medical applications require networked coordination between medical devices. However, most of the medical devices in use today do not support wireless communication or network connectivity. Currently, hospitals interested in coordinated medical care would have replace existing devices with expensive new devices. We believe that existing medical devices can be extended to support interoperable network connectivity. We demonstrate the Medical Device Dongle (MDD), an open-source platform that enables such extensions to current medical devices. The MDD can attach to any device that has a data output interface (RS-232 or USB) and enables it to connect wirelessly and in an interoperable manner for various applications. We show how multiple medical devices, including pulse oximeters and infusion pumps, can be connected and controlled together using an open-source platform, standards-based connectivity protocols, and model-driven software. The demo setup consists of medical devices attached to an MDD Agent, an MDD Manager device, and a mobile phone running monitoring applications. The MDD components can communicate over Bluetooth, WiFi and Ethernet.

The medical device dongle: an open-source standards-based platform for interoperable medical device connectivity

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.

Testing Autonomous Vehicle Software in the Virtual Prototyping Environment

Modern vehicle is equipped with autonomous features, such as precollision system or adaptive cruise control to help people perform driving in a safer and more convenient way. The software complexity of those autonomous features is growing to accommodate various needs from users, which makes it more difficult to test their correctness. Virtual prototyping allows one to test the vehicle software in the virtual road environment. Even though several tools are available, original equipment manufacturers seem to be hesitating to fully integrate the virtual test as a part of the vehicle development plan. One of the obstacle is due to a lack of well-defined test criteria that can reasonably abstract the physical environment and test case generation methods that automatically visualize the virtual road environment. In this letter, we propose several associated research directions and potential approaches from the perspective of test criteria and test case generation.

A Causality Analysis Framework for Component-Based Real-Time Systems

We propose an approach to enhance the fault diagnosis in black-box component-based systems, in which only events on component interfaces are observable, and assume that causal dependencies between component interface events within components are not known. For such systems, we describe a causality analysis framework that helps us establish the causal relationship between component failures and system failures, given an observed system execution trace. The analysis is based on a formalization of counterfactual reasoning, and applicable to real-time systems. We illustrate the analysis with a case study from the medical device domain.

The SMT-based automatic road network generation in vehicle simulation environment

Vehicle simulators are widely used to test the correctness of vehicle control algorithms. It is important to create a virtual road environment in a way that the vehicle algorithm can be tested under various circumstances that may happen in the real world. However, building such a road environment is typically time consuming and performed in a manual and ad-hoc fashion without having a good notion of coverage criteria. We propose the automatic road network generation for vehicle simulation that is based on Satisfiability Modulo Theories (SMT). We first introduce the curve coverage criteria to characterize the property of horizontal/vertical curves that are required to test advanced safety features such as adaptive cruise control or lane keeping assistance. This criteria includes the number of curves, the distance of adjacent curves and horizontal/vertical curvatures. We propose the road network generation algorithms that utilize the SMT solver to determine a set of 3 dimensional coordinates. This algorithm takes an input of the parametrized constraints formalized from the curve coverage criteria and automatically determines a set of 3D coordinates to generate the road structure. Vehicle simulation engines can then use these coordinates to visualize the road networks, and such road networks are guaranteed to conform to the curve coverage criteria. We developed a plug-in for the Unity3D simulation engine that automates this process and demonstrate the applicability of the generated the road network for the adaptive cruise control testing.

Automotive Software Certification: Current Status and Challenges

Modern vehicles can have millions of lines of software, for vehicle control, infotainment, etc. The correctness and quality of the software play a key role in the safety of whole vehicles. In order to assure the safety, engineers give an effort to prove correctness of individual subsystems or their integration using testing or verification methods. One needs to eventually certify that the developed vehicle as a whole is indeed safe using the artifacts and evidences produced throughout the development cycle. Such a certification process helps to increase the safety confidence of the developed software and reduce OEMs liability. However, software certification in automotive domain is not yet well established, compared to other safety-critical domains, such as avionics and medical devices. At the same time, safety-relevant standards and techniques, including ISO 26262 and assurance cases, have been well adopted. It finally promotes the adoption and development of software certification in the automotive industry. In this paper, we first present a survey of recent research in the domains of aviation, medical devices, and railway systems. After this survey, we summarize current status as well as existing challenges in the automotive software certification. Assurance cases are also presented as a promising technique to automotive software certification. Language: en