A real-time vital control module to increase capabilities of railway control systems in highly automated train operations

Recent advances in technology and railway have led to the introduction of systems and infrastructures capable of driving trains automatically. The Automatic Train Operation (ATO) system has been optimized for active human supervision. The next challenge is to realize ATO systems capable of achieving unsupervised operations on the mainlines. However, at this aim, additional safety functionalities should be provided. In this paper, we propose a pioneer hardware/software Vital Control Module (VCM) architecture capable of expanding the control capabilities of the existing train control system. The VCM includes a Printed Circuit Board (PCB), to be integrated into the cabin equipment, managed by a reliable and safe hard Real-Time Operating System (RTOS). Both hardware and software are developed to be compliant with related safety standards. The VCM integrates an application logic that acts as an on-board equipment control core, assessing the overall operativity in real-time, and promptly issuing emergency brakes if hazardous situations occur. The application logic has been developed with a model-based approach via Simulink/Stateflow tool and implemented as a C-script on the Xilinx Ultrascale + core housed on the PCB. We have used two testbeds to evaluate the VCM performance. Experimental results showed that the Worst-Case Response Time (WCRT) by the application logic is 13.6 times smaller than the most limiting specification-related deadline. The achieved earliness (- 1.8 ms out of 2 ms of deadline) allows for the easy expansion of VCM's train protection capabilities in the future. Results from the second testbed showed that the VCM can intervene to mitigate hazardous situations similar to 2 times faster than the current automatic train protection systems according to the related standard.

Automated summary

This paper proposes a pioneering hardware/software Vital Control Module (VCM) architecture to expand the control capabilities of the existing train control system. The VCM demonstrates good real-time operability and safety performance, and can promptly respond to emergency situations. Experimental results show that the VCM's response time is 13.6 times smaller than the most limiting specification-related deadline, effectively mitigating hazardous situations.