Design and Development of a Roaming Wireless Safety Emergency Stop
Henry Beuster, Thomas Doebbert, Christoph Cammin, Dmytro Krush, Gerd Scholl
TL;DR
The paper tackles the challenge of providing a secure, roaming emergency stop across multiple automation cells in dynamic manufacturing. It proposes a security-for-safety integration by combining IO-Link Wireless with IO-Link Safety, including encryption, authentication, and a Safety Process Data Unit, enabling dependable safety communication even as devices roam between cells. Through systematic measurements of roaming, connection/reconnection, and handover with and without the safety stack, the study demonstrates sub-second transition times under favorable signal conditions and identifies a consistent ~25 ms safety-handshake overhead. The work highlights the potential for increased flexibility, availability, and security in modern production environments and points to future enhancements such as AI-assisted radio optimization and location-aware handover decisions to further improve performance.
Abstract
Modern manufacturing is characterized by a high degree of automation, with autonomous systems also frequently being used. In such environments human intervention in the event of malfunctions or maintenance becomes a rare but also necessary task. When human workers are no longer an integral part of the production process, but only intervene when necessary, e.g., in the case of unexpected machine behavior, appropriate safety solutions will become even more important. This work describes a wireless communication system enabling a flexible and safe emergency stop function for multiple automation cells. A portable emergency stop switch allows seamless transition between different wireless cells, ensuring functional safety. The communication protocol combines IO-Link Wireless features with the safety requirements already implemented in IO-Link Safety. Security requirements are fulfilled through encryption and authentication. The IO-Link Wireless roaming functionality is used to extend the system across several manufacturing cells. An experimental setup confirms the suitability of the system for various applications. The results demonstrate the effectiveness of the handover mechanism and evaluate the potential of the system to improve flexibility, availability and security in dynamic production environments. Future extensions could include the use of AI based evaluation of the radio signals for an intelligent cell handover.