HMI Feedback Loop for Railway Safety
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Solution Overview
Problem
Current human machine interfaces (HMIs) in safety-critical applications, such as railway transportation, face challenges in ensuring the reliability of image display due to the use of off-the-shelf components, which can lead to incorrect information being shown even after faults, particularly in systems with high-resolution images displayed on multiple monitors.
Innovation Solution
A feedback control loop process using cryptographic techniques to securely manage and validate image data between an HMI Safe Server and HMI Terminal, ensuring only reliably tested images are displayed on COTS monitors, by employing symmetric and asymmetric encryption to authenticate and authorize image updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If off-the-shelf components are used in HMI systems, then system cost and ease of acquisition are improved, but reliability and control of image display deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the HMI terminal sends diagnostic information about its operational status to the HMI safe server. The safe server uses this feedback to determine whether to enable or disable image updates on the terminal, creating a closed-loop control system that monitors and responds to component health status in real-time.
Solution Approach 2:
The patent introduces an intermediary control mechanism where the HMI safe server acts as a mediator between the image generation system and the display output. The server controls the enabling/disabling of image updates based on diagnostic information, serving as a protective intermediary that prevents faulty components from displaying incorrect information.
2Reliability
If extensive testing and control mechanisms are implemented, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary actions by requiring the HMI terminal to conduct diagnostic tests on its own operational status before the safe server enables image updates. This advance testing prevents potential reliability issues from arising during critical operations, addressing reliability concerns proactively rather than reactively.
Solution Approach 2:
The HMI terminal performs self-diagnosis and self-monitoring of its operational status, generating diagnostic information about its own health without requiring external intervention. This self-service approach reduces the need for complex external monitoring systems while maintaining reliability.
3Ease of manufacture
If COTS components are used, then cost-effectiveness is improved, but control over internal details and failure modes deteriorates
Solution Approach 1:
The system establishes a feedback loop where the HMI terminal communicates its operational status to the safe server, enabling indirect monitoring and control of COTS component behavior without requiring knowledge of their internal implementation details.
Solution Approach 2:
The HMI safe server serves as an intermediary layer that abstracts the complexity of COTS components from the safety-critical control logic. The server interacts with terminal-level diagnostic interfaces to monitor component health, providing control over failure modes without needing to understand the internal architecture of commercial components.
Data Source
AI summary
The present invention relates to a method for remotely controlling the status of graphic user interfaces such as monitors, panels, displays, screens and others, used in railway or transportation systems. For achieving a reliable safety level, so that a person can be sure that the information displayed by the graphic interface in real time correspond to the effective situation of the transportation network, there is provided a feedback control loop between an image elaboration-generation block, and a safety block. According to a preferred solution, the communications between the blocks of the control loop are encrypted. With the control method of the present invention, it is possible to achieve a top safety level in the railway networks, even when using commercially available graphic user interfaces, such as COTS terminal.