Sampling Skew Error Correction in Process Devices
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Solution Overview
Problem
Industrial process control systems face errors due to time skew when sampling two or more process variables asynchronously, leading to significant measurement inaccuracies, particularly in dynamic common mode signals.
Innovation Solution
The implementation of compensation circuitry, including low pass filters and advanced extrapolation or interpolation techniques, such as linear and quadratic polynomial approximations, to predict process variable values and reduce errors caused by sampling skew, ensuring synchronized data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If asynchronous sampling of two process variables is performed, then system responsiveness and productivity are improved, but measurement precision deteriorates due to time skew errors
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the sampling rates of different process variables to achieve synchronization. The system modifies the sampling interval parameters adaptively, allowing asynchronous sampling to be transformed into synchronized sampling, thereby resolving the time skew error while maintaining high system responsiveness
Solution Approach 2:
The patent implements feedback mechanisms where the system continuously monitors the sampling timestamps of multiple process variables and uses this information to adjust future sampling operations. This feedback loop ensures that time skew errors are detected and corrected, maintaining measurement precision without sacrificing productivity
2Device complexity
If separate sampling of multiple process variables is performed, then device complexity is reduced, but measurement precision deteriorates due to sampling skew
Solution Approach 1:
The patent introduces an intermediary synchronization mechanism that coordinates the sampling of multiple process variables. This mediator component manages the sampling timestamps and ensures synchronization without requiring complex hardware modifications to each individual sensor, thus maintaining device simplicity while improving measurement precision
Solution Approach 2:
The patent applies preliminary action by pre-configuring synchronization parameters and sampling strategies before the actual measurement process begins. This preliminary setup ensures that subsequent sampling operations are automatically synchronized, eliminating time skew errors without adding complexity to the ongoing measurement process
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
An industrial process device (130) for monitoring or controlling an industrial process includes a first input configured to receive a first plurality of samples related to a first process variable PV1 and a second input configured to receive a second plurality of samples related to a second process variable PV2. Compensation circuitry (150A, B) is configured to compensate for a time difference between the first plurality of samples and the second plurality of samples and provide a compensated output related to at least one of the first and second process variables. The compensated output can comprise, or can be used to calculate a third process variable. The third process variable can be used to monitor or control the industrial process.