Network Delay Compensation for Control Loop Stability
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Solution Overview
Problem
Wireless and unstable network communication in distributed control systems leads to delays and jitters, affecting the stability of control loops in industrial processes, potentially causing oscillatory behavior and compromising safety and reliability.
Innovation Solution
A control device and system that adjust timing based on maximum delay times tolerated by the network, using data with time information to generate control data and compensate for delays, ensuring stable execution of control loops even over unstable networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless communication is used in distributed control systems, then ease of operation and installation are improved, but network delays and jitters occur causing control loop instability
Solution Approach 1:
The control device predicts future states of the controlled object based on historical data and system models before the actual control action is needed. This preliminary prediction compensates for the uncertain transmission time in wireless networks, allowing the control system to maintain stability despite network delays and jitters.
Solution Approach 2:
A communication management device is introduced as an intermediary between field devices and the control device. This intermediary manages communication resources, schedules data transmission, and minimizes network delays, thereby improving control loop stability while maintaining the benefits of wireless communication.
2Productivity
If data transmission time is reduced in wireless networks, then productivity is improved, but control precision deteriorates due to timing errors
Solution Approach 1:
The control device performs preliminary calculations and predictions of the controlled object's behavior in advance. By predicting future states based on system models and historical data, the control system can make accurate control decisions even with reduced data transmission time, maintaining control precision while improving productivity.
Solution Approach 2:
The system continuously monitors actual control outcomes and compares them with predicted values. This feedback mechanism allows the control device to adjust its predictions and compensate for timing errors, maintaining precision even when data transmission is accelerated for improved productivity.
Data Source
AI summary
A controller for using a first data item transmitted via a network to generate a second data item for controlling an entity to be controlled over the network, wherein the controller is characterized in being provided with: an adjustment unit for adjusting, with respect to the maximum delay time permissible on the network, the time by which generation of the second data item is started using the first data item after the first data item has been received; and a delay compensation unit, designed using a model of the entity to be controlled and the maximum delay time permissible on the network, for compensating for the delay of the first and second data items that can be generated using the network.