Verified Synthesis of Optimal Safety Controllers for Human-Robot Collaboration

TL;DR

This paper introduces a tool-supported method for synthesizing, verifying, and validating safety controllers in human-robot collaboration, ensuring correctness and safety compliance through formal methods and digital twin validation.

Contribution

The paper presents a novel integrated approach combining formal synthesis, verification, and validation of safety controllers tailored for collaborative robots in manufacturing.

Findings

Successfully synthesized a safety controller for a manufacturing work cell.

Verified the controller against safety correctness criteria.

Validated the controller in a digital twin environment.

Abstract

We present a tool-supported approach for the synthesis, verification and validation of the control software responsible for the safety of the human-robot interaction in manufacturing processes that use collaborative robots. In human-robot collaboration, software-based safety controllers are used to improve operational safety, e.g., by triggering shutdown mechanisms or emergency stops to avoid accidents. Complex robotic tasks and increasingly close human-robot interaction pose new challenges to controller developers and certification authorities. Key among these challenges is the need to assure the correctness of safety controllers under explicit (and preferably weak) assumptions. Our controller synthesis, verification and validation approach is informed by the process, risk analysis, and relevant safety regulations for the target application. Controllers are selected from a design space of feasible controllers according to a set of optimality criteria, are formally verified against correctness criteria, and are translated into executable code and validated in a digital twin. The resulting controller can detect the occurrence of hazards, move the process into a safe state, and, in certain circumstances, return the process to an operational state from which it can resume its original task. We show the effectiveness of our software engineering approach through a case study involving the development of a safety controller for a manufacturing work cell equipped with a collaborative robot.