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ESO-based super-twisting sliding-mode composite control for single-detector, pendulum-mirror PAT system in
Weipeng Li1, Zeshu Liu2, Chengzhi Jiang3
1School of Astronautics, Beihang University, Beijing, 100191, China; Key Laboratory of Spacecraft Design Optimization and Dynamic Simulation Technology, Ministry of Education, Beihang University, Beijing, 100191, China.
ISA Transactions
|August 6, 2026
Summary
This study introduces a novel composite control strategy for single-sensor pointing, acquisition, and tracking (PAT) systems in laser communication. The method enhances tracking precision by mitigating coupled disturbances between coarse and fine pointing assemblies.
Area of Science:
- Aerospace Engineering
- Control Systems Engineering
- Optical Communication Systems
Background:
- High-precision pointing and tracking (PAT) are crucial for inter-satellite laser communication, especially under dynamic disturbances.
- Existing single-sensor PAT systems face performance degradation due to coupled motions between coarse-pointing assembly (CPA) and fine-pointing assembly (FPA).
- The coupling issue in single-sensor PAT systems has been inadequately addressed in prior research.
Purpose of the Study:
- To propose a composite control strategy for single-sensor PAT systems to overcome measurement coupling.
- To improve tracking performance and reduce pointing errors in dynamic environments.
- To enable adjustable workload distribution between CPA and FPA.
Main Methods:
- Integration of an extended state observer (ESO) with a super-twisting sliding-mode controller.
- Incorporation of ESO-estimated information into the coarse-pointing loop to address measurement coupling.
- Formulation of an ESO-based sliding surface for workload allocation and disturbance rejection.
Main Results:
- Reduced root-mean-square pointing error by at least 5.5% and 2.5% compared to PID and twice-extended ADRC controllers, respectively.
- Decreased FPA driving voltage by over 15.3% and 85.2% compared to the same controllers.
- Validated effective workload distribution with CPA cutoff frequencies within 19% of theoretical predictions and confirmed real-time feasibility.
Conclusions:
- The proposed composite control strategy effectively mitigates coupled disturbances in single-sensor PAT systems.
- The method enhances pointing accuracy and reduces energy consumption in inter-satellite laser communication.
- The controller demonstrates real-time feasibility for high-speed, in-orbit applications.
