Systems-theoretic Safety Assessment of Robotic Telesurgical Systems (1504.07135v2)

Abstract: 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.

• The paper introduces a novel method combining STPA and fault injection to systematically identify safety hazards in robotic telesurgical systems.
• It conducted 2,146 fault injection experiments on the RAVEN II testbed, revealing 17 undetected scenarios mainly due to USB and motor feedback issues.
• The study highlights the need for improved monitoring and safeguards to enhance resilience in surgical robotic systems.

Systems-theoretic Safety Assessment of Robotic Telesurgical Systems

The paper entitled "Systems-theoretic Safety Assessment of Robotic Telesurgical Systems" offers an in-depth look at enhancing the safety of robotic telesurgical systems. This research applies a systems-theoretic approach using Systems-Theoretic Process Analysis (STPA) complemented by fault injection techniques to critically evaluate and validate the resilience of safety mechanisms in such complex systems.

Overview of Methodology

The core of this research lies in a novel methodology combining STPA with software-implemented fault injection. STPA, anchored in the Systems-Theoretic Accident Model and Processes (STAMP), was employed to identify potential safety hazards in the RAVEN II robotic surgical system. This system is utilized as a testbed owing to its open-source nature and relevance to telesurgical research.

To test the system's robustness against identified hazards, a software fault injection framework was developed. This framework simulated faults that could occur in real-world scenarios, as reported in the FDA MAUDE database. By targeting specific software locations derived from the STPA analysis, the paper aims to recreate and analyze the system's response to these fault scenarios.

Experimental Findings

The research conducted over 2,146 fault injection experiments, although a significant portion of the inserted faults did not manifest due to system crashes or unlogged effects. However, a subset of 368 fault situations was comprehensively documented. Notably, 17 scenarios illustrated undetected safety hazards—primarily those associated with system interoperability issues. Errors in USB communication and unmonitored feedback loops from motor controllers or brakes were recurrent themes in undetected hazards, underscoring vulnerabilities in the RAVEN II system’s safety mechanisms.

Safety hazards mitigated by the system's current protective measures include halting unauthorized movements and engaging brakes upon loss of control signals. Overdrive detection functions played a critical role in identifying unsafe commands and initiating appropriate emergency stops. However, the paper also highlights gaps where additional monitoring could preemptively address hazards.

Implications and Future Directions

This paper delineates the importance of refining robotic surgical systems' safety mechanisms, pointing out specific areas such as USB communication and motor feedback loops that require improvement. The approach adopted also offers broader implications for safety validation in medical cyber-physical systems. By using STPA to pinpoint potential hazard pathways and subsequently testing these through fault injection, a more realistic understanding of system failures in practice is achievable.

Future prospects entail integrating these findings into the design and development of next-generation robotic surgical devices. Ensuring robust error detection and recovery capabilities could significantly reduce downtime and potential patient harm during surgeries. The efficacy of such systems in handling faults contributes not just to practical safety improvements but also to theoretical advancements in how complex interactions in cyber-physical systems are managed.

This research, while grounded in a specific robotic system, offers a scaffold for evaluating other medical devices. Its contributions extend into the field of regulatory practices, urging the incorporation of systematic fault injection methodologies as part of safety validation frameworks in the clinical domain. As the field progresses, continuous feedback loops between theoretical hazard analysis and empirical testing will likely emerge as a standard practice in designing inherently safer robotic surgical systems.