This paper presents robust fault detection based on adaptive thresholds for a three axis satellite. For this purpose, first, the attitude control system (ACS) is described as a quasi linear parameter model that includes both bounded parametric modeling errors and measurement noises. Next, using the interval arithmetic tools, an interval linear parametric varying observer is designed to propagate the effect of satellite parametric uncertainties into the alarm limits. This idea enhances the robustness of fault detection system at the decision making stage. In other words, the adaptive thresholds are generated for evaluating the residuals. Obtained results show that the missing alarm rates are minimized by the developed method; also this approach detects small or incipient faults more effectively than the classical robust fault detection algorithms with constant thresholds. In the next part of paper, an isolation algorithm has been proposed using the fault tree approach. Also, an accommodation system has been designed based on reconfiguration of available actuators. Accordingly, after isolation of faulty reaction wheels using the developed fault tree library, the accommodation system turned them off and replaced the suitable magnetic tourqers instead of faulty reaction wheels. Therefore, despite occurrences of several failures in the ACS, attitude control error is kept limited.

Attitude Determination and Control Subsystem (ADCS) is one of the vital subsystem of satellites which has a significant role in performing satellites missions. On-Board Electronic (OBE) is the main part of this subsystem which executes attitude determination and control algorithms. In this paper design of OBE of ADCS in IUST-SAT is presented. Design of this equipment is carried out based on requirements and constraints which are extracted by hierarchical design procedure. Satisfying design constraints and achieving functional requirements simultaneously, is a major task, which is carried out successfully in this paper. Also for verification of performance of this equipment before a satellite's launch, in this paper a novel and low-cost real-time hardware in the loop test bed is provided. The presented test bed is capable of assessing ADCS's equipments in a real-time condition. Finally, performance of designed OBE is investigated by implementing detumbling and initial attitude acquisition control modes in the hardware in the loop test bed.

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