Wireless Control Loop Delay Adaptation for Stable Industrial Latency
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Solution Overview
Problem
Automated wireless industrial communication systems face challenges in managing latency due to interference and variability in wireless communication, which can lead to unacceptable delays and system failures, especially when traditional fieldbus systems are replaced by wireless technologies like Wi-Fi and cellular networks.
Innovation Solution
A method and device that act as a control node in automated wireless industrial systems, inserting a variable time delay into control communication loops, monitoring communication times, and adjusting these delays to match expected times, thereby managing latency and ensuring stable process operations by adjusting delays higher if communication times are low and lower if they are high.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless communication technologies (Wi-Fi, cellular) are used to replace traditional fieldbus systems, then ease of operation and adaptability are improved, but communication latency and reliability deteriorate due to interference and shared spectrum
Solution Approach 1:
The system dynamically adjusts the time delay parameter in the control communication loop based on real-time communication conditions. The control node continuously monitors communication performance and adapts the delay value to maintain stable latency despite wireless interference and channel variability, transforming a static system into one that responds to changing environmental conditions.
Solution Approach 2:
The invention implements a feedback mechanism where the control node monitors the actual communication time of control loops and uses this information to adjust the time delay parameter. This closed-loop feedback ensures that latency remains within acceptable bounds by continuously adapting to variations in wireless communication performance caused by interference and channel conditions.
2Adaptability or versatility
If wireless communication is used to replace fieldbus systems, then adaptability and ease of deployment are improved, but latency management and predictability worsen due to shared physical channel and interference
Solution Approach 1:
The system transforms the static time delay parameter into a dynamic variable that adapts to real-time communication conditions. By continuously monitoring communication performance and adjusting the delay value, the system maintains predictable latency despite the inherent variability of wireless channels, resolving the contradiction between adaptability and latency predictability.
Solution Approach 2:
The invention changes the parameter values of the control communication loop, specifically the time delay parameter, to optimize latency performance. By adjusting this parameter based on observed communication times and environmental conditions, the system achieves predictable latency characteristics while maintaining the adaptability benefits of wireless communication.
3Reliability
If variable time delay is inserted into control communication loops to manage latency, then latency predictability and system stability are improved, but communication loop duration increases
Solution Approach 1:
The system applies a time delay parameter that is carefully calibrated to be sufficient for latency management but not excessive. By using partial action (a controlled, moderate delay rather than maximum possible delay), the system achieves the necessary latency predictability and stability while minimizing the impact on communication loop duration, balancing both requirements.
4Loss of time
If time delay is adjusted dynamically based on communication time monitoring, then latency management and latency predictability are improved, but device complexity increases
Solution Approach 1:
The control node performs self-service by autonomously monitoring its own communication performance and automatically adjusting the time delay parameter without external intervention. This self-adjusting capability simplifies the overall system architecture by eliminating the need for complex external control mechanisms while achieving effective latency management through the device's own feedback loop.
Data Source
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AI summary
A method for use in an automated wireless industrial system comprising a device (100, 210,220) configured to act as a control node and at least one field level device (100), 230), wherein the method comprises: issuing a control communication (510); inserting at least one5 time delay (tk) to the control communication (520); noting (530) the communication time (TCL) for the communication; comparing (540) the time for communication (TCL) to an expected time for communication (TR); and determining (550) if any of the at least one time delay (tk) should be adapted, and if so, adapting at least that time delay (560).