Safe Reinforcement Learning using Formal Verification for Tissue Retraction in Autonomous Robotic-Assisted Surgery

TL;DR

This paper presents a Safe-DRL framework with formal verification to ensure safety in autonomous tissue retraction tasks during robotic-assisted surgery, addressing safety concerns in DRL applications for critical surgical procedures.

Contribution

It introduces a novel Safe-DRL approach combined with formal verification to guarantee safety constraints in surgical automation tasks.

Findings

Formal verification provides high-confidence safety guarantees.

Safe-DRL ensures robotic instruments stay within safe workspace.

The approach reduces risk of hazardous interactions during surgery.

Abstract

Deep Reinforcement Learning (DRL) is a viable solution for automating repetitive surgical subtasks due to its ability to learn complex behaviours in a dynamic environment. This task automation could lead to reduced surgeon's cognitive workload, increased precision in critical aspects of the surgery, and fewer patient-related complications. However, current DRL methods do not guarantee any safety criteria as they maximise cumulative rewards without considering the risks associated with the actions performed. Due to this limitation, the application of DRL in the safety-critical paradigm of robot-assisted Minimally Invasive Surgery (MIS) has been constrained. In this work, we introduce a Safe-DRL framework that incorporates safety constraints for the automation of surgical subtasks via DRL training. We validate our approach in a virtual scene that replicates a tissue retraction task commonly occurring in multiple phases of an MIS. Furthermore, to evaluate the safe behaviour of the robotic arms, we formulate a formal verification tool for DRL methods that provides the probability of unsafe configurations. Our results indicate that a formal analysis guarantees safety with high confidence such that the robotic instruments operate within the safe workspace and avoid hazardous interaction with other anatomical structures.