Development of adaptive fuzzy logic controller for satellite attitude control system

Abstract

Development of space is one of the main symbols of technological progress in the modern society. Therefore, as a developing country, Malaysia not left in becoming one of the countries involved in exploring the field of satellite technology. Generally, the satellite receives interference from various phenomena that occurred in space. These phenomena can disturb the satellite position at any time and condition. Thus, it is necessary to control the orientation and maintain the stability of satellite by the attitude control system (ACS). This project proposed an Adaptive Fuzzy controller for ACS of Innovative Satellite (InnoSAT) based on Direct Action and Hybrid type controller structure. The objective of this project is to compare the time response and tracking performance among the structures of controller. The parameters of universe of discourse are tuned on-line by adjustment mechanism which is an approach similar to a PID error that could minimize errors between actual and model reference output. This thesis also presents a Model References Adaptive Control (MRAC) as a control scheme in order to control time varying systems where the performance specifications are given in terms of reference model. All the controllers have been tested using InnoSAT system with some operating conditions such as disturbance, varying gain, measurement noise and time delay. In order to study new methods used in satellite attitude control, this thesis presents five structure of controllers. Three structures are from Direct Action type and two structures are from hybrid type. At first, Direct Action type controller such as Adaptive Fuzzy PD controller, Adaptive Fuzzy PI and Adaptive Fuzzy PID have been applied. However, the performances of these controllers are slightly degraded while the controllers are tested in real data which known as Y-Thomson data. Thus, hybrid structure such as Adaptive Fuzzy P + Fuzzy I + Fuzzy D and Adaptive Parallel Fuzzy PI + Fuzzy PD controllers are proposed to overcome the problem. To compare the performance with other controller, Fuzzy and Adaptive Fuzzy controllers with Weighted Recursive Least Square Algorithm is proposed. Simulation results show that all controllers that have been proposed have a good performance. Adaptive Fuzzy controller shows the best capability and stronger robustness from Fuzzy controller. Thus, the application of the Adaptive Fuzzy PI + Fuzzy PD controller is expected to be valuable. The contribution of this project is to bring this country for more advanced in satellite systems in future as well as for the international market.