The Research Of Helicopter Rotors Non-contact Icing Detection

Rotor is the lifting, manipulation and dynamics unit to helicopters. Compared toother components, rotor icing is of greatest peril to the safety flight of helicopters and hasattracted the research of home and abroad. The study of the rotor icing detection startedearly abroad and there has been a plenty of achievements in both experiments andapplications of this area. On the contrary, the research of the rotor icing in our countrystarts late and is almost blank up to now. The thesis brings forward an improvednon-contact infrared rotor icing detection system based on the original one, aiming at fillthe blank of research of this area.The thesis first gives an introduction of the features of icing of the rotor and pointsout that the icing width and velocity on the front edge instead of beneath the surface ofthe rotor should be studied as the primary object. Meanwhile, the thesis also conductsexperimental study of the icing width under the rotor surface. Based on that, the thesisintroduces the theory of infrared detection and puts forward the method of detection. Thethesis mainly introduces the design of signal processing circuits and DSP algorithm. Theinfrared ray which has been modulated is projected under the surface of the rotor and thereflected ray is transferred to electric signal through a photodiode. Then the signal ismagnified by preamplifier and mid-amplifier and then is extracted from backgroundnoise by a synchronous integrator. Then dual-threshold comparators, broadening circuitsand DSP system are designed to extract the icing information from the signals. Moreover,the thesis tries to introduce a comparator whose threshold can be automatically adjustedaccording to the amplitude of the signals. The thesis elaborates on the choices of infraredlaser source, photoelectric detector, the parameters and forms of the circuits.In the DSP software part, the thesis introduces the DSP, its on-chip recourses, theCETEK-VC5509-A study board and how to design DSP peripheral circuits based on the above. The thesis puts forward a compensation algorithm to overcome the influence ofthe pitching and flapping of the rotor. The thesis first proves the necessity of softwarecompensation through the results of static experiments. Then it proves the effectivenessof the algorithm though the results of dynamic experiments.The thesis has conducted a series of static and dynamic experiments under differentsimulation circumstances. The results of the experiments prove the feasibility ofapplication of the whole system.