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Active disturbance rejection for time-varying state-delay systems based on equivalent-input-disturbance approach
Meiliu Li1, Jinhua She2, Chuan-Ke Zhang1
1School of Automation, China University of Geosciences, Wuhan 430074, China; Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems, Wuhan 430074, China.
ISA Transactions
|September 22, 2020
Summary
This study introduces an improved PI control system using the equivalent-input-disturbance (EID) approach to effectively reject disturbances in systems with time delays. The new method significantly reduces tracking errors, enhancing control performance.
Area of Science:
- Control Systems Engineering
- Systems Theory
- Applied Mathematics
Background:
- Exogenous disturbances significantly degrade control performance in systems with time delays.
- Time-varying delays introduce complexities in accurately estimating and compensating for disturbances.
- Proportional-Integral (PI) control is widely used but can be challenged by these factors.
Purpose of the Study:
- To develop a robust disturbance rejection strategy for PI control systems with time-varying state delays.
- To integrate the equivalent-input-disturbance (EID) approach for enhanced disturbance estimation.
- To improve the overall control performance and stability of the system.
Main Methods:
- Integration of the equivalent-input-disturbance (EID) approach into a PI control framework.
- Development of an EID estimator to capture combined effects of time-varying delay and disturbance.
- Derivation of a less-conservative stability condition using Lyapunov-Krasovskii functionals and advanced inequality lemmas.
- Parameter calculation for controllers based on the derived stability condition.
Main Results:
- The proposed EID-enhanced PI control system effectively rejects exogenous disturbances.
- A novel, less-conservative stability condition was derived for improved system analysis.
- Engine idle speed control demonstrated significant performance improvements.
- Tracking errors were reduced to approximately one-third and one-sixth compared to generalized extended-state observer and sliding-mode control methods, respectively.
Conclusions:
- The EID approach integrated into PI control offers a superior method for disturbance rejection in systems with time-varying delays.
- The derived stability condition provides a more accurate assessment of system robustness.
- The method shows significant advantages over existing advanced control techniques in practical applications like engine idle speed control.
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