Dead Time Estimation Using Frequency Characteristics in Control Systems
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Solution Overview
Problem
Accurate estimation of dead time in control targets is crucial for enhancing control performance, as errors in dead time estimation can significantly affect control responsiveness and overshoot in PID control and other control-system designs.
Innovation Solution
A dead time estimation device that calculates the dead time using an evaluation function based on the frequency characteristic of a transfer function from which the dead time element is removed, allowing for precise estimation and consideration in control systems, including a configuration with a dead time initial value acquisition section and a frequency characteristic acquisition section to obtain accurate initial values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If dead time compensation control is performed using Smith compensation, then control responsiveness is improved and overshoot is suppressed, but control performance deteriorates when there is an error in dead time estimation
Solution Approach 1:
The patent employs an evaluation function that compares the actual frequency characteristic of the control target with the frequency characteristic of a model system. By minimizing the difference between these characteristics through feedback adjustment of the dead time parameter, the system achieves accurate dead time estimation while maintaining stable control performance even when initial estimates are inaccurate.
2Device complexity
If a simple dead time estimation method is used, then device complexity is reduced, but measurement precision of dead time deteriorates
Solution Approach 1:
The patent replaces complex iterative identification methods with a frequency characteristic-based evaluation function. By using frequency domain analysis and comparing magnitude and phase characteristics, the system achieves accurate dead time estimation through a more straightforward computational approach that minimizes device complexity while maintaining high measurement precision.
Data Source
AI summary
A dead time estimation device capable of accurately estimating a dead time in a control system is provided. A dead time estimation device 6 includes a dead time calculation section 64 configured to obtain a dead time L{circumflex over ( )}′1 with which an evaluation function J in Equation (1) is at minimum[Equation 7]J=∫|Ĝ/e−{circumflex over (L)}′<sub2>1</sub2>s−Ĝ′|df (1)where G{circumflex over ( )}/e−L∧′1s is a frequency characteristic of an element from which a dead time element is removed from a transfer function of a control target P and G{circumflex over ( )}′ is a transfer function not including the dead time element in the control target P.