Title of the Paper: Mixed H2/H∞ Self-Adaptive Fuzzy Algorithm
to Control Satellite Attitude
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Authors: Guo-Shing Huang, Zhi-Liang Zhang
Abstract: The main purpose of this paper is to propose a nonlinear H∞ and mixed d H2 /H∞ self-fuzzy
algorithm to solve large-angle robust control problem. The attitude control is one of the studied
problems in recent years. Under the space environment, there often exists an unpredictable
interference which results some deviations of satellite’s attitude. Therefore, it needs to develop a
controller still to keep the control ability to the system with respect to the uncertainty of the satellite
system and unpredictable environment interference in order to achieve the required control goal and
performance specification. In this paper, consider one ROCSAT-3 hardware structure, and use selffuzzy
fuzzy algorithm to perform the attitude control with the time varying and uncertainty parameters.
Then, we combine the nonlinear H∞ and mixed H2 /H∞ control law to reduce the impact of the
satellite’s attitude system due to external disturbance. Through simulation results, it is shown that
the proposed design method can make the ROCSAT-3 system efficiently achieve the desired
stability and reject the external interference.
Keywords: Nonlinear H∞ control, Nonlinear mixed H2 /H∞ control, Self-fuzzy algorithm, Attitude
control, Time varying parameter
Title of the Paper: Time Syntonization and Frequency Stabilizing Using GPS Carrier
Phase with Extension Controller
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Authors: Guo-Shing Huang
Abstract: This study discusses time syntonization and frequency stability calibration using GPS carrier
phase measurements. Thus far most papers on this subject discussed using two GPS receiver measurements,
and performing frequency stabilizing and vehicle positioning with the double differences. This paper proposes
using a dual frequency GPS receiver and a novel extension controller neural network algorithm that can achieve
the frequency stabilizing and coordinate positioning. The oscillation frequency of the rubidium atom clock is
selected first as the satellite atom clock oscillation frequency as the criterion for adjusting the GPS receiver
oscillator＇s frequency. The receiver’s oscillation frequency is synchronized with the reference atomic clock
oscillation frequency using the designed extension controller and extension neural network. To finish the
frequency stabilizing and time syntonization, the time can be calibrated and the position precision on the
vehicle improved. The position precision can be improved from about 3.5 meters to about 1.5 meters using the
extension controller. The time error is improved from about 4.85×10−7 seconds to about 2 .8 5 × 1 0 − 8 seconds.
Using the extension neural network to verify the position precision allows improvement from about 3.5 meters
to about 1.3 meters. The time error is improved from about 4.85×10−7 seconds to about 2 .8 × 10 − 8 seconds.
The system was verified experimentally as satisfying the exactness, feasibility and robustness of the initial
concept.
Keywords: GPS, Carrier Phase, Extension Controller, Extension Neural Network
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