Research On False Alarm Reducing Technology In The BIT Of Helicopter Heading Attitude System

The Built-in test (BIT) is an integral capability of the mission system or equipment which provides an automated test capability to detect, diagnose or isolate failures. It is an important technical way by which the testability and the fault detection of mechatronic systems can be remarkably improved. The false alarm is a fault indicated by BIT or other monitoring circuitry where no fault exists. The high false alarm rate is the main problem which puzzles the research and application of the BIT technology.The heading attitude system is the key part of the helicopter, its working state directly influences the reliability and the sufficient readiness of the helicopter. Because of the structural character and the flight character, the heading attitude system endures high noise, intense vibration and big temperature span, and sustains rigor test of the environmental factors during the flight. The strong vibration and variable temperature may cause serious false alarm problems of the heading attitude system BIT. Aiming at this problem, the research on false alarm reducing technology in the BIT of helicopter heading attitude system is proposed. The main content of the research is as follows.1. The mechanisms of the false alarm of the heading attitude system BIT are analyzed systematically and deeply.(1) According to the factors that caused the false alarm of general mechatronic systems BIT, the factors that caused the false alarm of the heading attitude system BIT are summarized by the theoretical analysis and experimental analysis. They include: environmental factors, the heading attitude system itself, improper BIT design, the factitious or other unknown factors. The environmental stress is the main factor that caused the BIT false alarm of the heading attitude system.(2) Aiming at the false alarm that caused by environmental factors, the rule of the false alarm is described by the qualitative theoretical analysis. The analysis of the false alarm mechanisms of the heading attitude system BIT is made. It establishes the theoretical base for the overall false alarm reducing blueprint, and makes preparation for the following research.2. An overall false alarm reducing blueprint of the helicopter heading attitude system BIT is presented.(1) Based on the theoretical analysis, an overall false alarm reducing plan is presented. Aiming at the factors that caused the false alarm of the heading attitude system BIT, the solution plan and implementation method are proposed respectively.