Systems-theoretic Safety Assessment of Robotic Telesurgical Systems

Robotic telesurgical systems are one of the most complex medical cyber-physical systems on the market, and have been used in over 1.75 million procedures during the last decade. Despite significant improvements in design of robotic surgical systems through the years, there have been ongoing occurrences of safety incidents during procedures that negatively impact patients. This paper presents an approach for systems-theoretic safety assessment of robotic telesurgical systems using software-implemented fault-injection. We used a systemstheoretic hazard analysis technique (STPA) to identify the potential safety hazard scenarios and their contributing causes in RAVEN II robot, an open-source robotic surgical platform. We integrated the robot control software with a softwareimplemented fault-injection engine which measures the resilience of the system to the identified safety hazard scenarios by automatically inserting faults into different parts of the robot control software. Representative hazard scenarios from real robotic surgery incidents reported to the U.S. Food and Drug Administration (FDA) MAUDE database were used to demonstrate the feasibility of the proposed approach for safety-based design of robotic telesurgical systems.Comment: Revise based on reviewers feedback. To appear in the the International Conference on Computer Safety, Reliability, and Security (SAFECOMP) 201

Integrated Cyber-Physical Fault Injection for Reliability Analysis of the Smart Grid

The term Smart Grid broadly describes emerging power systems whose physical operation is managed by significant intelligence. The cyber infrastructure providing this intelligence is composed of power electronics devices that regulate the flow of power in the physical portion of the grid. Distributed software is used to determine the appropriate settings for these devices. Failures in the operation of the Smart Grid can occur due to malfunctions in physical or cyber (hardware or software) components. This paper describes the use of fault injection in identifying failure scenarios for the Smart Grid. Software faults are injected to represent failures in the cyber infrastructure. Physical failures are concurrently represented, creating integrated cyber-physical failure scenarios that differentiate this work from related studies. The effect of these failure scenarios is studied in two cases: with and without fault detection in the distributed software. The paper concludes by utilizing the information gained to refine and improve the accuracy of the quantitative reliability model presented in our earlier work

Data-driven resiliency assessment of medical cyber-physical systems

Advances in computing, networking, and sensing technologies have resulted in the ubiquitous deployment of medical cyber-physical systems in various clinical and personalized settings. The increasing complexity and connectivity of such systems, the tight coupling between their cyber and physical components, and the inevitable involvement of human operators in supervision and control have introduced major challenges in ensuring system reliability, safety, and security. This dissertation takes a data-driven approach to resiliency assessment of medical cyber-physical systems. Driven by large-scale studies of real safety incidents involving medical devices, we develop techniques and tools for (i) deeper understanding of incident causes and measurement of their impacts, (ii) validation of system safety mechanisms in the presence of realistic hazard scenarios, and (iii) preemptive real-time detection of safety hazards to mitigate adverse impacts on patients. We present a framework for automated analysis of structured and unstructured data from public FDA databases on medical device recalls and adverse events. This framework allows characterization of the safety issues originated from computer failures in terms of fault classes, failure modes, and recovery actions. We develop an approach for constructing ontology models that enable automated extraction of safety-related features from unstructured text. The proposed ontology model is defined based on device-specific human-in-the-loop control structures in order to facilitate the systems-theoretic causality analysis of adverse events. Our large-scale analysis of FDA data shows that medical devices are often recalled because of failure to identify all potential safety hazards, use of safety mechanisms that have not been rigorously validated, and limited capability in real-time detection and automated mitigation of hazards. To address those problems, we develop a safety hazard injection framework for experimental validation of safety mechanisms in the presence of accidental failures and malicious attacks. To reduce the test space for safety validation, this framework uses systems-theoretic accident causality models in order to identify the critical locations within the system to target software fault injection. For mitigation of safety hazards at run time, we present a model-based analysis framework that estimates the consequences of control commands sent from the software to the physical system through real-time computation of the system’s dynamics, and preemptively detects if a command is unsafe before its adverse consequences manifest in the physical system. The proposed techniques are evaluated on a real-world cyber-physical system for robot-assisted minimally invasive surgery and are shown to be more effective than existing methods in identifying system vulnerabilities and deficiencies in safety mechanisms as well as in preemptive detection of safety hazards caused by malicious attacks

An enabling environment for independent power producers in renewable electricity

The increasing demand for electricity, the rising price of energy from conventional sources and limited electricity supply are a global concern. The demand on electricity generation could be alleviated by diversifying the sources from which electricity is obtained to achieve the goals of long-term electricity supply. Diversification implies finding alternative sources of energy such as renewable energy for the production of electricity. The South African electricity system is under increased pressure to provide and maintain electricity supply to its users. Electricity production may be regarded as a key contributor to the social and economic development of South Africa. The challenges are so serious that it will gradually become increasingly difficult to extract sufficient resources to satisfy increasing electricity demand. Growth in the electricity and industrial sectors signifies profound changes in the entire energy industry. The South African power utility Eskom, supplies 94% of South Africa’s electricity but the risk of inadequate supply because of increasing electricity demand is mitigated through the employment of Independent Power Producers (IPPs) which supply to the grid. However, although a limited number of IPP entrepreneurs sell electricity to the Eskom grid, there is no enabling entrepreneurial environment in which they can thrive. There is no positive movement to inaugurate policies and processes. This has created an opportunity for Smart Grid access as a viable option to accommodate IPP entrepreneurs into the grid. Investing in renewable electricity sources may provide feasible alternatives for the electricity industry, it would alleviate pressure on current supply whilst creating an enabling entrepreneurial environment for IPP entrepreneurs and increase entrepreneurial activity. This study investigates a proposed model for an enabling entrepreneurial environment for IPPs in the RE sector that can be utilised to ensure increased entrepreneurial activity within the electricity industry. Establishing such an enabling environment would contribute positively to the alleviation of the electricity demand crisis, result in lower carbon emissions and create a sustainable, more diverse electricity generation mix. This proposed IPP industry model for an enabling entrepreneurial environment is presented to address the problems experienced at the different levels of the electricity industry. The model can be utilised to increase entrepreneurial activity while eradicating major electricity challenges at different levels in the South African electricity industry. The results indicate that that RE, in the form of solar and wind, has the potential to expand the South African electricity industry significantly. Therefore, in order to reform the South African electricity industry, stakeholders need to embrace entrepreneurship as IPP entrepreneurs. This can be done effectively by the incorporation of IPP entrepreneurs into the electricity network. However, an enabling entrepreneurial environment in which to operate must be ensured. In this study, five important variables support the establishment of an enabling entrepreneurial environment for IPP entrepreneurs. These have been identified as; Smart Grids, Entrepreneurship, Renewable electricity environment, SA policy and Stakeholder theory. An important contribution has been made towards Stakeholder Theory. This has proven to be instrumental within the RE sector of the electricity industry in South Africa, as the mentioned role players have a reciprocal role to play. Three surveys were conducted at three levels of the electricity industry, namely, at organisational, legislative and entrepreneurial levels and included Eskom Management, National Energy Regulator (NERSA) Management and Approved and Non-approved IPPs. Both qualitative and quantitative research methods were utilised in this research study. The results indicate that SA Policy is instrumental in assisting stakeholders to facilitate the IPP process and feed the power from RE generation into the network. Most respondents were positive about the role of Smart Grids in future electricity generation and their contribution towards creating an enabling entrepreneurial environment for IPP entrepreneurs. Respondents indicated that by policy decisions, greater emphasis can be placed on the results of climate change and environmental challenges. Emphasis on the incorporation of stakeholders proved imperative to this group (IPPs). The results indicated that stakeholder management is a key factor contributing to the establishment of an enabling entrepreneurial environment. The major contribution of this study is a proposed entrepreneurial model that can improve future sustainability of the electricity supply