飛航紀錄器水下定位精進研究

Abstract

本研究目的為建立拖曳式水下麥克風陣列偵搜定位系統，作為海上空難時探測飛行紀錄器的偵搜設備。當飛航紀錄器落入水中後，其配備之水下定位發報器遇水後觸發內部機制，以固定週期產生特定脈衝訊號，搜救人員可根據此訊號於海上搜索飛機殘骸，進而下載紀錄器資料以釐清空難發生原因。本研究利用拖曳式水下麥克風陣列定位水下發報器位置，運用各麥克風元件接收目標訊號之到達時間差做方位角解算，並將結果以網格劃分方式結合至實際海域範圍，定位出一個可能性較高之聲源位置，藉此輔助判定飛航紀錄器實際位置。 此研究與洋聲股份有限公司、海洋委員會國家海洋研究院、國家運輸安全調查委員會合作，利用拖曳式水下麥克風陣列偵搜定位系統於臺灣小琉球南方海域進行實海域試驗。結果顯示，當麥克風陣列與聲源（Source level約160 dB）距離小於1公里時，目標訊號8.8 kHz的定位誤差為150至300公尺，目標訊號37.5 kHz的定位誤差為83公尺；當與聲源距離超過1公里時，目標訊號8.8 kHz的定位誤差為70公尺。此研究之方法不僅可定位水下發報器位置，供搜救團隊於救援過程中快速鎖定打撈範圍，亦能了解眾多參數對定位結果之影響，從中尋找出搜救時之最佳方案，加強定位效能。

The aim of this study was to establish a towed underwater hydrophone array localization system as a rescue device for detecting flight recorders during maritime accidents. When a flight recorder falls into the water, its built-in underwater locator beacon is triggered upon contact with water, generating specific pulse signals at regular intervals. Search and rescue personnel could use these signals to search for the aircraft wreckage at sea and subsequently recover the flight recorder to determine the cause of the accident. This study focuses on real-time localization and utilizes a towed underwater hydrophone array to locate the underwater beacon. The arrival time differences of the target signals (TDOA) received by each hydrophone are used for bearing angle calculations, and the results are combined with a grid division approach in the actual sea area to determine a high probability location of sound source. This assists in determining the possible location of the flight recorder.

This research is conducted in collaboration with OceanSound CO., LTD., National Academy of Marine Research (OAC), and Taiwan Transportation Safety Board. The towed underwater hydrophone array localization system is tested in the southern waters of Xiao Liuqiu, Taiwan. The array is towed at different depths to compare the accuracy of localization under different background environments. Two common frequencies of underwater locator beacons are used as target signals for signal processing and performance comparison. The results show that when the distance between the hydrophone array and the sound source (source level approximately 160 dB) is less than 1 kilometer, the localization error is between 50 and 150 meters. When the distance exceeds 1 kilometer, the localization error for an 8.8 kHz source is within 300 meters. This study not only enables the localization of underwater beacons to provide rescue teams with a narrowed-down searching area, it also identifies the localization results with various parameter. Therefore, it would be possible coming out with an optimal solution for rescue, enhancing precision of localization results.