@techreport{oai:jaxa.repo.nii.ac.jp:00042975,
 author = {又吉, 直樹 and 奥野, 善則 and 井之口, 浜木 and Matayoshi, Naoki and Okuno, Yoshinori and Inokuchi, Hamaki},
 month = {May},
 note = {独立行政法人航空宇宙技術研究所の実験用ヘリコプタMuPAL-εには、機体位置情報を含む慣性データを計測するためのセンサとしてDGPS/INS(ディファレンシャルGPSと慣性航法装置を複合化したもの)が搭載されている。このDGPSの測位精度をより高精度なKGPS(キネマティックGPS)およびレーザ・トラッカによる計測結果との比較によって評価した。DGPSの補正情報として当所の所有する地上局を用いた場合の測位精度(95％確率値)は、水平面内0.4m、鉛直面内0.9mであった。海上保安庁が全国で運用する中波ビーコン局のDGPS補正信号を利用した場合の測位精度や受信安定性についても併せて評価を行った。さらにPDOP(GPS衛星の配置条件を表す指標)、飛行高度および速度、DGPS地上局からの距離などの条件が測位精度に及ぼす影響についても明らかにした。また、機体上部に位置するメインロータやエンジンなどの影響によってマルチパスが発生し、シュードレンジに最大1.5m程度の誤差が生ずること、およびこれらの周辺構造物によってGPSアンテナの覆域に死角が生じ、特に旋回時などに低仰角のGPS衛星からの電波が受信不能になる現象など、ヘリコプタ搭載時特有の問題点について明らかにした。, This paper presents the results of flight test evaluation of the DGPS (Differential Global Positioning System) installed on the MuPAL-epsilon research helicopter of the National Aerospace Laboratory of Japan (NAL). This system provides accurate aircraft position data, whose specification is 1 m horizontally (1 sigma). Two different sources of DGPS correction data can be selected: NAL's GPS ground station via a UHF telemetry system, or a medium frequency radio beacon signal from the GPS ground stations operated by the Japan Coast Guard (JCG), which are originally designed for ships' navigation. Since 27 JCG stations provide coverage all around the coast of Japan, no additional ground facilities are required except when operating in mountainous areas. Off-line kinematic GPS (KGPS) data and a laser tracker system were used to provide reference data to verify the DGPS positioning accuracy. The following results were obtained: 1) The DGPS positioning accuracy using NAL's GPS ground station is 0.4 m horizontally and 0.9 m vertically (95 percent) in steady flight conditions. 2) The influences of the following parameters on the positioning accuracy were clarified: PDOP (Position Dilution of Precision), flight altitude, flight speed, and baseline length. 3) The JCG DGPS stations were found to be useful for helicopter navigation because their correction signals were received stably throughout the flights and the positioning accuracy is much the same as that of the NAL's ground station. 4) Multipath receptions are caused by the obstacles around the MuPAL-epsilon's GPS antenna such as a main rotor and engines, which degrades the pseudo-range accuracy by 1.0 to 1.5 m. Signals from low elevation GPS satellites are even blocked by these obstacles especially during a turning flight., 資料番号: AA0047382000, レポート番号: NAL TR-1460},
 title = {実験用ヘリコプタ搭載DGPSの測位精度等評価飛行実験},
 year = {2003}
}