Adaptive Sampling Rate Control for Feedback Systems
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Solution Overview
Problem
Determining an appropriate sampling rate for feedback control systems is challenging, as too fast a rate can lead to improper tuning of proportional gain, while too slow a rate can impair performance, especially in dynamic systems with external disturbances.
Innovation Solution
A method that monitors error signals for disturbance events, estimates the time constant of the control process, and adjusts the sampling rate based on this estimation, selecting a sampling interval between one-fortieth and the estimated time constant, and updates the sampling rate if it differs significantly from the previous rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the sampling rate is increased to improve controller response speed, then the response time is reduced, but the proportional gain becomes too small leading to improper tuning
Solution Approach 1:
The patent applies dynamics by making the sampling rate adjustable rather than fixed. The controller automatically adapts the sampling rate based on system conditions and estimated time constants, allowing the system to optimize between response speed and tuning accuracy dynamically. This resolves the contradiction by enabling fast response when needed while maintaining proper gain tuning when conditions allow.
Solution Approach 2:
The patent changes the sampling rate parameter based on estimated time constants of the controlled process. By calculating the time constant from system response and adjusting the sampling rate accordingly (typically to 1/10th of the time constant), the system maintains optimal proportional gain values while achieving appropriate response speeds for different process dynamics.
2Measurement precision
If the sampling rate is decreased to improve proportional gain tuning, then the measurement precision is improved, but the controller performance suffers due to slow response
Solution Approach 1:
The system dynamically adjusts the sampling rate based on real-time estimation of process time constants rather than using a fixed low rate. This allows the controller to maintain high performance by sampling at the optimal rate for current system conditions, ensuring both accurate gain tuning and responsive control action.
Solution Approach 2:
The controller performs self-tuning by automatically estimating its own process time constant from the error signal response and adjusting its sampling rate accordingly. This self-service capability eliminates the need for manual configuration and ensures the controller operates at optimal performance without external intervention.
3Reliability
If manual adjustment and trial-and-error methods are used to determine sampling rate, then the ease of operation is reduced, but the reliability of parameter selection is improved
Solution Approach 1:
The controller automatically estimates the process time constant from the error signal and calculates the optimal sampling rate without requiring manual input or trial-and-error adjustment. This self-service approach maintains high reliability in parameter selection while significantly improving ease of operation, as the system configures itself autonomously.
Solution Approach 2:
The system uses feedback from the error signal response to estimate the process time constant and determine the appropriate sampling rate. By continuously monitoring system response and adjusting parameters based on observed behavior, the controller achieves reliable parameter selection automatically, eliminating the need for manual tuning while maintaining accuracy.
Data Source
AI summary
A control system for a plant includes a controller configured to detect a disturbance in the control system. In response to detecting the disturbance, the controller is configured to evaluate a signal affected by the disturbance to estimate a response time of a plant. The response time is a parameter that characterizes a response of the plant to the disturbance. The controller is configured to adjust an operating parameter used by the control system based on the estimated response time. The controller is configured to use the adjusted operating parameter to generate and provide an input to the plant.