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Failures of the air data system due to exceptional weather conditions have shown to be among the leading causes of aviation accidents. In this respect, most of aircraft Pitot tube failure detection schemes rely on mathematical models and simplified assumptions on the uncertain parameters and disturbances. These methods typically require “ ad hoc ” time-consuming tuning procedures that may produce unreliable performance when validated with actual flight data. In this paper, a complete semiautomated data-driven approach is introduced to select the model regressors, to identify NARX input–output prediction models, to set up robust fault detection filters and to compute fault detection thresholds. To cope with time-dependent and flight-dependent levels of uncertainties online model adaption mechanisms are introduced to limit the critical problem of minimizing the false alarm rate. Extensive validation tests have been conducted using actual flight data of a P92 Tecnam aircraft through the introduction of artificially injected hard and soft failure of the Pitot tube sensor. The approach showed to be remarkably robust in terms of false alarms while maintaining fault detectability to faults of amplitudes less than 1 m/s.

航空機搭載用風計測センサとして宇宙航空研究開発機構(JAXA)で開発された超音波速度計は、対気速度ゼロから3軸の対気速度が計測可能という利点を有し、ヘリコプタの対気速度センサとしても適している。しかし、ヘリコプタにおいて低速域で精度良く対気速度を計測するためには、センサ単体の性能だけではなく、機体周りの気流の影響による誤差(位置誤差)を小さくする必要があり、センサ搭載位置の選定が重要となる。このため、超音波速度計をノーズブーム先端に装備する形態(ノーズブーム形態)と胴体下面に直接装備する形態(胴体下面形態)の2通りの形態について、対気速度の計測精度、特に低速域での計測精度を評価する飛行試験をJAXAの実験用ヘリコプタMuPAL-εを用いて実施した。計測精度の評価に当たっては、先に風洞試験により超音波速度計の機器単体誤差を計測し、飛行試験結果である対気速度の計測誤差から機器単体誤差を取り除いてセンサ搭載位置における位置誤差を分離した。飛行試験の結果、ホバリングや後進においては、メインロータのダウンウォッシュの影響のためセンサ搭載位置の気流の乱れが大きく対気速度の計測は不可能であったが、ノーズブーム形態では前進速度10kt(5.1m/s)以上、胴体下面形態では前進速度20kt(10m/s)以上で2軸(胴体下面形態)あるいは3軸(ノーズブーム形態)の対気速度が計測可能であった。, The Japan Aerospace Exploration Agency (JAXA) has been developing a new airspeed sensor, called an Ultrasonic Velocimeter (USV), which can measure three-axis airspeed with high accuracy at a high sampling rate. The USV has a great advantage as a helicopter airspeed sensor since it works even at low airspeeds where conventional Pitot-static systems are ineffective. However, in determining the 'position error' of a helicopter's airdata sensor, the difference between airflow at the location of an airspeed sensor and the freestream airflow, becomes significant at low airspeeds because the airflow around a helicopter is then dominated by main rotor downwash. JAXA therefore conducted a flight test evaluation of the USV using its research helicopter MuPAL-epsilon. In the flight test, two different installation configurations, in which the USV is attached at the tip of the nose boom (configuration A) and attached to the bottom of the fuselage (configuration B), were evaluated. Two- or three-axis helicopter airspeeds were measured successfully when the forward speed was over 10 kt in configuration A, and over 20 kt in configuration B. In hovering, sideways and backward flights, the main rotor downwash prevented accurate airspeed measurements in both configurations., 資料番号: AA0048699000, レポート番号: JAXA-RM-04-019

航空宇宙技術研究所では、航空機の誘導・航法・制御技術、ならびにヒューマン・ファクタなどに関する研究成果の実証、および航空機搭載用機器の運用評価などを実飛行環境下で行なうための実験環境として、多目的実証実験機MuPAL(Multi-Purpose Aviation Laboratoryの略)プロジェクトを推進してきた。ドルニエ式Do228型機を母機とする実験機はMuPAL-α(ミューパル・アルファ)と名付けられ、フライ・バイ・ワイヤ操縦装置および直接揚力制御装置によりインフライト・シミュレーション機能を持つ。計測システムは、高精度計測機能と様々なセンサ・システムに対応できる汎用性を持つ。各種飛行実験の基本となる対気速度データは、機体のノーズブーム先端に取り付けられたピトー管により取得することが出来るが、この計測値には機体自身が機体周辺の空気の流れを乱す影響で、位置誤差と称する誤差を生ずる。この位置誤差を求めるためには、現在のところ飛行実験によって推定するしか方法がなく、様々な手法が試されている。今回は従来から定評のあり精度の高い静圧基準法、および原理が単純で信頼性の高い速度基準法それぞれを行った。位置誤差推定飛行実験の結果、巡航形態では対気速度の計測値に2.1％加算し、着陸形態では1.4％加算すれば、より精確な対気速度が求められることが明らかになった。, The National Aerospace Laboratory of Japan (NAL) has developed a new in-flight simulator named MuPAL-alpha designed to flexibly meet the requirements of flight testing in the fields of aircraft guidance, navigation and control, especially pilot-vehicle interfaces. MuPAL-alpha is based on a Dornier Do-228 and equipped with a Fly-By-Wire control system and a Direct Lift Control system to enable variable stability and response capability. The data acquisition system is characterized by its ability to handle the data from a variety of sensor systems as well as its sensors with a high level of accuracy. Airspeed derived using a pitot-static system on the nose boom of the aircraft provides the most basic data in every flight experiment. However the measured airspeed has an error known as a position error, arising from the disturbance caused by the aircraft as it moves through the air. This position error of the aircraft must be determined by flight testing for each test aircraft. The freestream static pressure and speed course methods are used to determine the position error. Both methods have become easier and more accurate in recent years by utilizing GPS. The flight test showed the position error to be 2.1 percent for clean configuration and 1.4 percent for landing configuration., 資料番号: AA0047396000, レポート番号: NAL TM-776