Research On Key Technology Of Helicopter Fire Detection

The traditional fire alarm system of helicopter engine compartment has the features of high rate of false positives and false negative. Thus, the safety of personnel on helicopter would be threatened. In this thesis, the method of ultraviolet fire detection based on PIC30F5011 is proposed to realize the reliable monitoring of the fire in the helicopter engine compartment. The detection system can accurately monitor the fire, detector faults, line faults, and transmit the results to the host-computer in time. Then the pilot can carry out corresponding operations according to the monitoring results to ensure that the system is in normal condition. In order to improve the stability and reliability of this system, redundancy design is adopted in the hardware design. Meanwhile, self-test and watchdog design are adopted in the software design. The following researches are carried out in this thesis:(1) The principle, the applicable occasions, the advantages and disadvantages of various types of fire detector are analyzed. In view of bad working environment of helicopter engine, the type of GD-2J ultraviolet detector is selected in this thesis, which has the features of high signal-to-noise ratio, wide detection range and high temperature resistance.(2) The performance requirements and functional requirements of the helicopter engine cabin fire alarm system are analyzed. According to the actual situation, the whole scheme of detection system is determined. The system is able to monitor the fire danger in time and ensure the stable communication between MCU and Host-Computer as well.(3)In the system hardware design, double power redundancy design and double watchdog redundancy design are used in this thesis. Meanwhile, the design of dual CPU redundancy scheme implemented by the CAN communication is presented and the optocoupler isolation module is designed in this thesis as well.(4)In the system software design, the method of duration analysis for fire recognition is used. Power on self-test and periodic self-test program are designed in this thesis. RS422 is adopted to realize the communication between MCU and host computer.