JP2004255978A - Information processing device, orbit control device, artificial satellite, and communication device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a distance between satellites when two satellites meet, while avoiding a collision of the satellites each other, in a plurality of non-geostationary satellites having mutually crossed orbits. <P>SOLUTION: This information processing device determines an angle from the satellite of the first orbit up to the meridian line passing an orbit intersection X point as a reference angle when a vertex on a right upper side of a holding range of the satellite of the first orbit overlaps with an intersection of a first parallel locus parallel to the first orbit and a second parallel locus parallel to a second orbit. By arranging the satellite of the second orbit at a position where an angle from the satellite of the second orbit up to the meridian line passing the orbit intersection X point becomes more than the reference angle, each of the satellite of the first orbit and the satellite of the second orbit can be made to pass each meeting point without overlapping the holding range of the satellite of the first orbit and the holding range of the satellite of the second orbit. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

具体的な例として、ｉ が４５度のとき ｃｏｓ ｉ＝１／√２ゆえ、
ｔａｎ ａ＝√（３／２） となり、ａ＝５０．７６８４８ 度となることがわかる。
【００１４】
図１８は第２の軌道に関して、近地点、遠地点、昇交点、降交点、第１の衛星の軌道との会合点を示した図である。この幾何的な関係は、第１の軌道および第３の軌道でも全く同じように成り立つ。これは、３つの軌道の軌道面が赤道面垂直まわりに１２０度づつ離れ、軌道長半径すなわち軌道周期、離心率、軌道傾斜角、近地点引数がそれぞれ等しいためである。図１８において図１５および図１６と同じ記号で表わされた要素Ｏ、Ｂ’、Ｄ’、Ｈ’、Ｉ’、ａは図１５および図１６と同じであることを示す。点Ｌは軌道の近地点を示し、点Ｍは次の軌道との会合点を示す。点Ｍはアプサイド線Ｄ’Ｌに関して点Ｂ’と対称な位置にある。角度ｆは近地点Ｌから点Ｂ’までのなす角であり真近点離角と呼ばれる角度である。
３つの衛星が会合点で順次会合するとは、第２の軌道で見たとき、点Ｂ’で第１の軌道の衛星と第２の軌道の衛星が会合し、その後第１の軌道の衛星とは離れ、第２の軌道の衛星が遠地点Ｄ’を経て会合点Ｍに到達した時、第３の軌道の衛星が点Ｍに現れてそこで会合する事象を、３つの衛星ごとに順番に繰り返すことを指す。従って、この事象が起きるためには会合点Ｂ’から次の会合点Ｍに至るまでの時間が軌道周期の３分の１であれば良い。反対に、３分の１と異なる場合は順次会合することは起らない。
図１８で、近地点Ｌから遠地点Ｄ’までの所要時間は遠地点Ｄ’から近地点Ｌまでの所要時間に等しく軌道周期の２分の１である。点Ｂ’から点Ｄ’までの所要時間は点Ｄ’から点Ｍまでの所要時間に等しく軌道周期の６分の１である。また、点Ｌから点Ｂ’までの所要時間は点Ｍから点Ｌまでの所要時間に等しく軌道周期の３分の１である。このことから、会合するための３つの衛星の配置の典型的な例として、或る時点で衛星がそれぞれ各軌道の点Ｂ’、点Ｍおよび点Ｌに居る場合が挙げられる。
３つの軌道で軌道長半径、離心率、軌道傾斜角、近地点引数が等しく、かつ軌道長半径、軌道傾斜角の値が与えられ近地点引数が２７０度で、３つの軌道の軌道面が赤道面垂直まわりに１２０度づつ離れている、即ち昇交点が１２０度ずつ離れているとき、会合点Ｂ’から次の会合点Ｍまでの所要時間が軌道周期の３分の１になるためには、近地点Ｌから会合点Ｂ’までの所要時間が軌道周期の３分の１であれば良く、それが成り立つ離心率は特定の値になる。この離心率の求め方を以下に示す。
近地点Ｌから会合点Ｂ’までの所要時間が軌道周期の３分の１であることから、点Ｂ’の平均近点離角ｍは、
ｍ＝（２×π）／３
である。これは、平均近点離角で表わした軌道周期が２×πであることによる。
平均近点離角ｍと離心近点離角ｇと真近点離角ｆの関係式として、次の式が良く知られている。
ｔａｎ （ｆ／２）
＝√（（１＋ｅ） ／ （１−ｅ）） × ｔａｎ （ｇ ／ ２）
ｍ＝ｇ − ｅ×ｓｉｎ ｇ
ここで、ｅ が求める離心率である。
真近点離角ｆは角度ａを用いて次のように表わされる。
ｆ＝π−ａ
【００１５】
以上をまとめると、軌道傾斜角ｉから角度ａが求められ、ａから真近点離角ｆが求められ、ｆとｍからｅが求められる。なお、これらの式からわかるようにｆとｍからｅを求める式は超越方程式となり直接に解析的に求めることができず繰り返し法のような数値計算で求めることになる。
具体的な例としてｉ＝４５度の時、ａ＝５０．７６８４８ 度となり、数値計算によりｅ＝０．０９９ となることがわかる。
【００１６】
このように、本実施の形態に係る情報処理装置の対象とする非静止衛星の例である準天頂衛星は、昇交点赤経がほぼ１２０度づつ異なり、即ち軌道面がほぼ１２０度づつ回転した配置になり、等軌道傾斜角（４５度）、等近地点引数（２７０度）かつ等周期（ほぼ静止周期、２３時間５６分）の３つの衛星軌道において、それぞれの軌道上を飛行する衛星が各軌道の会合点で会合するように、３つの軌道に共通な離心率（０．０９９）が設定されている。
【００１７】
図２は衛星直下点の地表上の軌跡を示す。
その軌跡は非対称８の字の形をしており、８の字の交点が図１の会合点そのものを示す。図１では３つの軌道が示されているが、それらの軌道要素を上記のように設定することで衛星直下点の地表軌跡は１つの８の字となる。各衛星が遠地点または近地点に位置するときその直下点の経度は東経１３５度であり、衛星が会合点から遠地点を経て次の会合点にいたるときその直下点の軌跡は８の字の交点から始まり北緯４５度東経１３５度の衛星直下地点を経て８の字の交点に再び戻ってくる。この期間（約８時間）の衛星は日本上空に滞在し、日本から衛星を見た時の仰角は約７０度以上となり、山や建物の陰に入る可能性は通常の静止衛星にくらべて低くなる。
２つの衛星が会合点で会合する場合、例えば、第３軌道の衛星と第１軌道の衛星とがＣ点にて会合する場合（地上局が通信対象とする衛星が第３軌道の衛星から第１軌道の衛星に切替る場合）は、衛星に送信される信号は地上局のアンテナから第３軌道の衛星に向かって送られており、ここで衛星に送信される信号が第１軌道の衛星にも送られるよう第３軌道の衛星向けとは異なる周波数で第１軌道の衛星への送信が開始される。そして、地上局における切替え処理が完了すると、第３軌道の衛星への送信が停止され、代わりに第１軌道の衛星が地上との通信を継続して担当することになる。
ここで、第３軌道の衛星と第１軌道の衛星とが会合する際に、第３軌道の衛星と第１軌道の衛星とが衝突することなく地上局が同一のアンテナで２つの衛星に同時に信号を送り出すことが出来る程度に接近していることが望ましい。
このため、本実施の形態に係る情報処理装置では、２つの衛星が会合する際に、２つの衛星が衝突することなく地上局の同一のアンテナで２つの衛星に同時に信号を送り出すことが出来る程度に接近して会合するように各衛星の位置関係を決定する。
【００１８】
図３は、本実施の形態に係る情報処理装置４０の構成例を示すブロック図である。
【００１９】
入力部４０１は、オペレータから各種の指示を入力する。
表示部４０２は、情報処理装置４０の処理結果等を表示ディスプレイに表示する。
【００２０】
許容偏差角度決定部４０３は、各衛星がそれぞれの衛星軌道を周回する際の周回位置偏差の許容偏差範囲である許容偏差角度を決定する。許容偏差角度は、地球の中心を基準とする衛星の位置から許容偏差までの角度である。
【００２１】
第１の平行軌跡設定部４０４は、軌道面偏倚角度決定の対象となる衛星（以下、第２の人工衛星という）の軌道面偏倚角度決定の際に基準となる衛星（以下、第１の人工衛星）の衛星軌道から許容偏差角度だけ離れた位置に第１の衛星の衛星軌道に平行な平行軌跡（第１の平行軌跡）を設定する。ここで、本明細書では、平行とは衛星軌道と一定間隔を保って衛星軌道に並走していることをいい、平行軌跡とは衛星軌道から許容偏差角度だけ離れた位置を保って衛星軌道に並走する軌跡をいう。衛星軌道は曲線からなるが、衛星軌道に並走する軌跡を平行軌跡とよぶ。
図４は、第１軌道の衛星を第１の人工衛星とし、第２軌道の衛星を第２の人工衛星とした例を示しており、１３は第１軌道１０から許容偏差角度だけ離れた第１軌道１０に平行する平行軌跡であり、第１の平行軌跡である。
【００２２】
第２の平行軌跡設定部４０５は、第２の人工衛星の衛星軌道から許容偏差角度だけ離れた位置に第２の人工衛星の衛星軌道に平行な平行軌跡（第２の平行軌跡）を設定する。同様に、図４において、２３は第２軌道２０から許容偏差角度だけ離れた第２軌道２０に平行する平行軌跡であり、第２の平行軌跡である。
【００２３】
第１の保持範囲設定部４０６は、第１の人工衛星の周りに第１の保持範囲を設定する。
第１の保持範囲とは、第１の人工衛星がとどまるべき範囲であり、第１の人工衛星を中心とし２辺が第１の平行軌跡上にある矩形をいう。
衛星の軌道は地球偏平による重力偏向や月・太陽の引力、太陽輻射圧の影響で次第にずれてくるが、衛星軌道に対するずれの限度を定めるのが保持範囲であり、保持範囲を逸脱しそうな場合には、衛星は軌道制御スラスタ即ちガスジェットを噴射することで軌道修正を行う。
この保持範囲に常に衛星をとどめておくことで、通信用アンテナを精度良く所定の地上方向に向けておくことが出来、他の衛星への電波干渉や物理的な衝突を回避することが可能になる。
図４の１４は、第１の人工衛星たる第１軌道の衛星の保持範囲、すなわち第１の保持範囲を示している。図４では、第１の保持範囲１４は、第１軌道の衛星の位置１１から各辺までの間が許容偏差角度分離れている正方形としている。
なお、地球方向には保持範囲を設ける必要はない。
【００２４】
第２の保持範囲設定部４０７は、第２の人工衛星の周りに第２の保持範囲を設定する。
第２の保持範囲とは、第２の人工衛星がとどまるべき範囲であり、第２の人工衛星を中心とし２辺が第２の平行軌跡上にある矩形をいう。
図４の２４は、第２の人工衛星たる第２軌道の衛星の保持範囲、すなわち第２の保持範囲を示している。図４では、第２の保持範囲２４は、第２軌道の衛星の位置２２から各辺までの間が許容偏差角度分離れている正方形としている。なお、地球方向には保持範囲を設ける必要はない。
【００２５】
軌道情報記憶部４０８は、各衛星の軌道情報を記憶している。軌道情報とは各衛星が周回すべき軌道の軌跡を示す情報である。
【００２６】
基準角度算出部４０９は、第２の人工衛星の軌道面偏倚角度を決定する際の基準となる基準角度を算出する。基準角度の内容については後述する。
【００２７】
軌道面偏倚角度決定部４１０は、第１の人工衛星の軌道面偏倚角度を決定するとともに、第１の人工衛星の軌道面偏倚角度に基づき第２の人工衛星の軌道面偏倚角度を決定する。
【００２８】
次に、本実施の形態に係る情報処理装置４０における軌道面偏倚角度の決定原理を説明する。
図５は、軌道面偏倚角度の決定原理を説明するための図である。
図５では、第１軌道の衛星を第１の人工衛星とし、第２軌道の衛星を第２の人工衛星とした例を示している。昇交点赤経が１２０度づつ異なり、即ち軌道面が１２０度づつ回転した配置になり、等軌道傾斜角（４５度）、等近地点引数（２７０度）かつ等周期（ほぼ静止周期、２３時間５６分）で３つの軌道に共通な離心率（０．０９９）が設定されている３つの衛星軌道において、それぞれの軌道上を飛行する衛星が各軌道の会合点で遭遇するように配置できることはすでに述べた。しかし、会合点で遭遇することは衛星の衝突の可能性があり避けなければならない。このため、３つの軌道上を飛行する衛星が各軌道の会合点で遭遇するように配置した軌道で、第２軌道の軌道面を赤道面に垂直で地球中心を通る軸まわりに少し回転移動する。図５の２６は回転移動する前の第２軌道を示す。回転移動する前の第２軌道の会合点Ａ点に対して、Ａ点の回転移動後の点を会合点ＡＡ点と呼ぶ。また、断わりなく第２軌道と呼ぶ時は回転移動後の第２軌道を意味する。図５において、第１軌道の衛星は会合点Ａ点の位置にあり、第２軌道の衛星は会合点ＡＡ点の位置にある。そして、第１の平行軌跡１３の上方の平行軌跡と第２の平行軌跡２３の上方の平行軌跡とが交差する点（平行軌跡交点）にて、第１軌道の衛星の保持範囲１４の右上方の頂点と第２軌道の衛星の保持範囲２４の左上方の頂点とが重複している。この状況では、第１軌道の衛星と第２軌道の衛星とは保持範囲の重複点にて衝突する可能性があるが、第１軌道の衛星の保持範囲１４と第２軌道の衛星の保持範囲２４とが一点において重複するものであるため、前述のように第２軌道の軌道面を赤道面に垂直で地球中心を通る軸まわりに少し回転移動することにより、図５での両衛星間の横方向の間隔が広がるため、両衛星は衝突する危険性がなくなる。図４は、図５に示す状態になる直前の両衛星の位置関係（第２軌道の衛星が会合点ＡＡ点の手前にある状態）を示しているが、第１軌道の衛星の保持範囲１４と第２軌道の衛星の保持範囲２４とが重複しておらず、衝突の危険性がない。また、図６は、図５に示す状態の直後の両衛星の位置関係（第１軌道の衛星が会合点Ａ点を通り過ぎた状態）を示しているが、第１軌道の衛星の保持範囲１４と第２軌道の衛星の保持範囲２４とは重複しておらず、衝突の危険性がない。
このように、両衛星が衝突する危険性があるのは両衛星が図５に示す位置関係にある場合であり、図５に示す位置関係から第２軌道の衛星の軌道面を赤道面に垂直で地球中心を通る軸まわりに少し回転移動することにより、両衛星間の横方向の間隔が広がり、両衛星は衝突する危険性がない。換言すれば、第１の保持範囲１４の右上方の頂点が第１の平行軌跡と第２の平行軌跡との交点（平行軌跡交点）上にあるときに第２の保持範囲２４の左上方の頂点が既に平行軌跡交点を通過済みであれば、両保持範囲は重複せず、両衛星が衝突する危険性がない。
このことは、第１の保持範囲１４の右上方の頂点が平行軌跡交点に重なる際の第１軌道の衛星〜会合点Ａ点を通る子午線の角度よりも第２軌道の衛星〜会合点Ａ点を通る子午線の角度の方が大きければ、両保持範囲は重複せず、両衛星が衝突する危険性がないことを意味する。
【００２９】
このため、本実施の形態に係る情報処理装置４０は、第１の保持範囲１４の右上方の頂点が平行軌跡交点に重なる際の第２軌道の衛星〜会合点Ａ点を通る子午線の角度が第１軌道の衛星〜会合点Ａ点を通る子午線の角度よりも大きくなるように第２軌道の衛星の軌道面偏倚角度を決定する。
なお、第１の保持範囲１４の右下方の頂点が第２の平行軌跡の内側にあり右上方の頂点が平行軌跡交点に重なる際の第１の人工衛星の位置を基準位置という。例えば、図５に示す第１軌道の衛星は基準位置にある。
【００３０】
次に、図７のフローチャートを参照して、本実施の形態に係る情報処理装置４０の軌道面偏倚角度決定手順を説明する。
まず、ステップＳ７０１において、第１の人工衛星と第２の人工衛星とを決定する。図１に示した第１軌道の衛星、第２軌道の衛星、第３軌道の衛星のうちのいずれを第１の人工衛星及び第２の人工衛星とするかについて入力部４０１がオペレータより指示を入力し、軌道面偏倚角度決定部４１０は、入力部４０１からの入力結果に従い、第１の人工衛星とする衛星、第２の人工衛星とする衛星を決定する。
【００３１】
次に、ステップＳ７０２において、許容偏差範囲を決定する。入力部４０１がオペレータより許容偏差角度の値を入力し、許容偏差角度決定部４０３が入力された値を許容偏差角度として決定し、記憶する。
次に、ステップＳ７０３において、第１の平行軌跡、第２の平行軌跡を設定する。第１の平行軌跡設定部４０４及び第２の平行軌跡設定部４０５がそれぞれ第１の平行軌跡及び第２の平行軌跡を設定する。具体的には、第１の平行軌跡設定部４０４は第１の人工衛星の軌道情報を軌道情報記憶部４０８より読み出し、許容偏差角度決定部４０３により決定された許容偏差角度に基づき第１の人工衛星の衛星軌道（以下、第１の衛星軌道という）から許容偏差角度だけ離れた位置に２つの平行軌跡を設定する。また、第２の平行軌跡設定部４０４は第２の人工衛星の軌道情報を軌道情報記憶部４０８より読み出し、許容偏差角度決定部４０３により決定された許容偏差角度に基づき第２の人工衛星の衛星軌道（以下、第２の衛星軌道という）から許容偏差角度だけ離れた位置に２つの平行軌跡を設定する。
【００３２】
次に、ステップＳ７０４において、第１の人工衛星の軌道面偏倚角度を決定する。入力部４０１がオペレータから第１の人工衛星の軌道面偏倚角度を入力し、軌道面偏倚角度決定部４１０による処理を経て軌道情報記憶部４０８が第１の人工衛星の軌道面偏倚角度を記憶する。具体的には、特定の位置、例えば、第１の人工衛星が第２の人工衛星との会合点に到達すべき時刻をオペレータより入力し、軌道面偏倚角度決定部４１０がオペレータから入力された時刻に基づき第１の衛星軌道上の各位置について到達時刻を算出し、第１の到達時刻情報として軌道情報記憶部４０８に記憶させる。
【００３３】
次に、ステップＳ７０５において、第１の保持範囲を設定する。第１の保持範囲設定部４０６は、軌道情報記憶部４０８に記憶された第１の人工衛星の軌道情報を読み出し、第１の衛星軌道上の各位置について第１の保持範囲を設定し、第１の保持範囲設定情報として軌道情報記憶部４０８に記憶させる。
【００３４】
次に、ステップＳ７０６において、第１の人工衛星の基準位置とその時刻（基準時刻）とを特定する。軌道面偏倚角度決定部４１０が、軌道情報に記憶された第１の人工衛星の軌道情報、第１の到達時刻情報及び第１の保持範囲設定情報に基づき、第１の人工衛星の基準位置、すなわち、図５に示すように第１の人工衛星の保持範囲の右上の頂点と平行軌跡交点とが重なるときの第１の人工衛星の位置を特定し、また、第１の人工衛星が当該基準位置に到達する時刻を基準時刻として特定する。
【００３５】
次に、ステップＳ７０７において、第１の人工衛星の基準位置と会合点を通る子午線との間の角度（基準角度）を算出する。基準角度算出部４０９が、ステップＳ７０６で特定された第１の人工衛星の基準位置と会合点を通る子午線との間の角度を算出して基準角度とする。
【００３６】
次に、ステップＳ７０８おいて、会合点を通る子午線から基準角度以上離れた位置を基準時刻における第２の人工衛星の位置とし、第２の人工衛星の軌道面偏倚角度を決定する。軌道面偏倚角度決定部４１０は、会合点を通る子午線から基準角度以上の角度が離れた第２の衛星軌道上の位置を特定し、第２の衛星軌道上の当該位置を基準時刻における第２の人工衛星の位置とする。つまり、基準時刻に、第１の人工衛星は会合点を通る子午線から基準角度分離れた位置（＝基準位置）に存在し、第２の人工衛星は会合点を通る子午線から基準角度以上離れた位置に存在するようにする。このようにして決定した基準時刻における第２の人工衛星の位置に基づき第２の衛星軌道の各位置について第２の人工衛星の到達時刻を算出し、第２の到達時刻情報として軌道情報記憶部４０８に記憶させる。
【００３７】
次に、ステップＳ７０９において、第２の人工衛星の保持範囲を設定する。第２の保持範囲設定部４０７が軌道情報記憶部４０８に記憶された第２の人工衛星の軌道情報を読み出し、第２の衛星軌道上の各位置について第２の保持範囲を設定し、第２の保持範囲設定情報として軌道情報記憶部４０８に記憶させる。
【００３８】
以上のようにして第２の人工衛星の軌道面偏倚角度を決定することにより、第１の人工衛星と第２の人工衛星は第１の保持範囲と第２の保持範囲とを重複させることなくそれぞれ会合点を通過することができ、第１の人工衛星と第２の人工衛星とが衝突する危険性を回避することができる。
【００３９】
例えば、図１における第１軌道の衛星を第１の人工衛星とし、第２軌道の衛星を第２の人工衛星として第２軌道の衛星の軌道面偏倚角度を決定した場合には、第２軌道の衛星を第１の人工衛星とし、第３軌道の衛星を第２の人工衛星とし、図７に示した手順に従って処理することで第３軌道の衛星の軌道面偏倚角度を決定することができる。但し、既に許容偏差角度、第２軌道の衛星の軌道面偏倚角度及び第２軌道の衛星の保持範囲は決定しているので、ステップＳ７０２〜Ｓ７０５は省略する。
【００４０】
また、これまでの説明とは逆に、図５における第２軌道の衛星を第１の人工衛星とし、第１軌道の衛星を第２の人工衛星とし、第２軌道の衛星の位置に基づいて第１軌道の衛星の軌道面偏倚角度を決定する場合は、図５に示す第２軌道の衛星の位置（第２軌道の衛星の保持範囲の左下方の頂点が第１軌道の人工衛星の平行軌跡の内側にあり左上方の頂点が平行軌道交点に接するときの第２軌道の衛星の位置）を基準位置とし、第２軌道の衛星が基準位置にあるときの第２軌道の衛星と会合点Ａ点を通る子午線との間の角度を基準角度とする。
【００４１】
次に、具体的な数値を用いて、第２の人工衛星の軌道面偏倚角度の決定手順について説明する。
以下では、許容偏差角度を０．１度とした場合を例にして説明する。
図８は、図５に示した状態と同じ状態を示しているが、説明の便宜上、第１軌道の衛星及び第２軌道の衛星の位置は省略し、第１の保持範囲及び第２の保持範囲のみを表示している。また、図８では、第１軌道と第２軌道の交差角度を具体的に示している。また、上述したように、本例では許容偏差角度を０．１度としているため、第１軌道から第１の平行軌跡までの角度は０．１度、第２軌道から第２の平行軌跡までの角度も０．１度となる。また、第１軌道の衛星から第１の保持範囲の各辺までの角度は０．１度であり、第１の保持範囲の各辺の長さに相当する角度は０．２度となっている。また、第２の保持範囲も同様であり、第２軌道の衛星から第２の保持範囲の各辺までの角度は０．１度であり、第２の保持範囲の各辺の長さに相当する角度は０．２度となっている。
また、以下では、第１軌道の衛星を第１の人工衛星との例とし、第２軌道の衛星を第２の人工衛星の例として説明する。
【００４２】
図８では、それぞれの保持範囲がＸ点で接している（第１軌道の衛星が基準位置にある）。Ｘ点は第１の平行軌跡の上方の平行軌跡と第２の平行軌跡の上方の平行軌跡とが交差する平行軌跡交点である。Ｚ点は第１軌道と第２軌道とが交差する軌道交点である。Ｙ点は第１の保持範囲のうち前方の辺と第１軌道とが重なる点である。
球面三角形ＺＸＹを取り上げたとき、Ｙ点が第１の保持範囲の辺上にあることから、内角Ｙは９０度となる。第１軌道と第２軌道は図１に示した軌道要素を取ることから、これら２つの軌道のなす角は１０４．４７８度および７５．５２２度となり、内角Ｚは１０４．４７８度の２分の１の５２．２３９度となる。また、第１の保持範囲が＋／−０．１度の正方形であることから、辺ｚ（角Ｚに対抗する辺角）は０．１度である。
直角球面三角形の公式から、辺ｘ（角Ｘに対向する辺角）は次のように表わされる；
ｓｉｎ ｘ＝ｔａｎ ｚ ／ ｔａｎ Ｚ
上記数値を用いて辺ｘを求めると、０．０７７度となる。
第１の保持範囲の中心位置（＝第１軌道の衛星の位置Ａ点）から第１の保持範囲の各辺までの角度は０．１度であるから、第１の保持範囲の中心位置（＝第１軌道の衛星の位置Ａ点）からＺ点までの角度は ０．０７７＋０．１＝０．１７７ 度となる。ここで、図８の対称性から、Ａ点とＡＡ点を結ぶ線分は、Ｘ点およびＺ点を通る子午線と直交する。この交点をＵ点とする。球面三角形ＡＺＵにおいて、内角Ｕは９０度であり、角ｕ（角Ｕに対向する辺角）は上記のあるように、０．１７７度である。内角Ｚは１０４．４７８度の２分の１の５２．２３９度である。
直角球面三角形の公式から、辺ｚ（角Ｚに対向する辺角）は次のように表わされる；
ｔａｎ ｚ＝ ｃｏｓ Ａ・ｔａｎ ｕ ，ｃｏｓ ｕ ＝ ｃｏｔ Ａ・ｃｏｔ Ｚ
上記数値を用いて辺ｚを求めると、０．１４０度となる。
この０．１４０度は基準角度（Ａ点から軌道交点Ｚ点を通る子午線までの角度、即ちＡ点とＵ点の間の角度）に相当する。また、図８において、幾何的関係は図の上下方向と左右方向に関して対称であるから、Ｚ点から第２の保持範囲の中心位置（＝第２軌道の衛星の位置ＡＡ点）までの角度も同様に０．１４０度となる。図８では、第１の保持範囲と第２の保持範囲とがＸ点において重複するため、第２の保持範囲を、第２軌道の軌道面を赤道面に垂直な地心を通る軸まわりに回転させて東西方向にずらせば、第１の保持範囲と第２の保持範囲とは重複しない。このため、第１軌道の衛星と軌道交点Ｚ点を通る子午線との間の角度が０．１４０度である際に第２軌道の衛星を軌道交点Ｚ点を通る子午線から０．１４０度より大きな角度を離した位置に配置すれば、第１軌道の衛星と第２の軌道の衛星は第１の保持範囲と第２の保持範囲とを重複させることなく軌道交点Ｚ点を通過することができる。
【００４３】
また、第２軌道の衛星と軌道交点Ｚ点を通る子午線との間の角度の最大値については、Ｋｕバンド使用の４５ｃｍ直径パラボラアンテナのビーム幅は３度（ｐ−ｐ）であることから、ハンドオーバ時にパラボラアンテナの中心が１つの衛星を指向している時、他の衛星が１．５度以内の離れ角であれば同じアンテナで２つの衛星をカバーすることが可能となる。このため、ハンドオーバ時に２つの衛星を同時に１つのユーザーアンテナでカバーするために、２つの衛星のはなれ角の上限を１．５度とするのが適当であると考えられる。第１軌道の衛星と軌道交点Ｚ点を通る子午線までの角度は０．１４０度なので、軌道交点Ｚ点を通る子午線と第２軌道の衛星との間の角度は、１．５−０．１４０＝１．３６０度を上限とするのが適当である。
【００４４】
以上より、許容偏差角度を０．１度とした場合には、基準角度を０．１４度とし、第１の人工衛星と軌道交点を通る子午線との間の角度が０．１４度となる際の第２の人工衛星と軌道交点を通る子午線との間の角度が０．１４度よりも大きな角度であって１．３６度以下の角度となるように第２の人工衛星の軌道面偏倚角度を決定する。軌道交点の緯度がほぼ２６．５７度であるから、球面三角法により第１の人工衛星の衛星軌道と第２の人工衛星の各々の昇交点赤経の差は０．３１度以上１．６８度以下となる。
【００４５】
図９は図５に第２軌道の衛星の理想の位置２１を追加した図である。第２軌道の衛星の理想の位置とは、第１軌道の衛星と同時に会合点Ａに到達することになる回転移動前の第２軌道２６の衛星の位置である。
第２軌道の衛星が理想の位置にある場合には、第１軌道の衛星と同時に会合点Ａに到達するので、第２軌道の衛星の理想の位置と軌道交点Ｚ点を通る子午線との角度は、第１軌道の衛星の位置１１と軌道交点Ｚ点を通る子午線との角度に等しく、その角度は０．１４度である。
従って、図９において、幾何的関係は図の上下方向と左右方向に関して対称であるから、第２軌道の衛星の理想の位置２１と第２軌道の衛星の位置２２（第１の保持範囲と第２の保持範囲とが平行軌道交点にて重複する位置）とのなす角度は０．１４度の倍の０．２８度となる。このため、第２の保持範囲の離れ角、正確には第２軌道の衛星の理想の位置２１と第２の保持範囲の中心位置との離れ角が０．２８度であると、第１軌道の衛星と第２軌道の衛星の２つの衛星の衝突が防止されることがわかる。つまり、０．２８度は衝突防止のための最小値であり、０．２８度以上であればよい。最大値は、地上の端末から見て一度に２つの衛星が補足できる範囲で有ればよい。
【００４６】
図１０は、図１に各衛星の理想位置及び実際の位置を書き加えた図であり、図１１は、図２に各衛星の理想位置及び実際の位置を書き加えた図である。
図１０では、第１軌道の衛星が会合点Ｃ点に到達する際の状況を示している。第１軌道の衛星１１の実際の衛星位置は理想の位置に一致する。また、第３軌道の衛星の理想の位置３１は第１軌道の衛星の実際の位置１１に一致する。このように、理想の位置では各会合点Ａ、Ｂ、Ｃでおのおのの理想の位置が一致する。軌道要素のなかで理想の衛星位置の真近点離角は各々１２９．２３度、０度、２３０．７７度である。
そして、これまで説明してきたように、衛星間の衝突の可能性をなくするため、第２軌道と第３軌道での実際の衛星位置を理想の衛星位置から積極的に＋／−０．２８度ずつおのおのの軌道面を赤道面に垂直で地球中心を通る軸まわりにずらしてある。第２軌道においては、第２軌道の衛星の実際の位置２５は理想の位置２１から０．２８度その衛星を含む軌道面を赤道面に垂直で地球中心を通る軸まわりに回転させた位置とし、第３軌道においては、第３軌道の衛星の実際の位置３５は理想の位置３２から−０．２８度その衛星を含む軌道面を赤道面に垂直で地球中心を通る軸まわりに回転させた位置としている。
図１１では、第１軌道の衛星は丁度交点上にあり南から登ってきており、第３軌道の衛星は交点に向かって北から降りてきている。衛星に送信される信号は地上局のアンテナから第３軌道の衛星に向かって送られており、ここで衛星に送信される信号が第１軌道の衛星にも送られるよう第３軌道の衛星向けとは異なる周波数で第１軌道の衛星への送信を開始する。その際、第３軌道の衛星と第１軌道の衛星が接近していることから同一のアンテナで２つの衛星に同時に信号を送り出すことが出来る。また、地上局のアンテナとおのおのの衛星までの距離がほぼ同じであるため、信号切り替え時に必要となる送信信号の遅延時間制御が容易になる。このあと、第３軌道の衛星への送信が停止され、代わりに第１軌道の衛星が地上との通信を継続して担当することになる。
【００４７】
このように、許容偏差角度を０．１度にした場合には、第２軌道の衛星及び第３軌道の衛星のそれぞれについて理想の衛星位置から０．２８度回転させた位置を実際の位置とすれば、２機の衛星が会合する際にもそれぞの保持範囲を重複させることなく会合することができ、衝突の可能性を回避することができる。
【００４８】
なお、以上では、図１に示す衛星軌道を周回する人工衛星、すなわち、昇交点赤経がほぼ１２０度づつ異なり、即ち軌道面がほぼ１２０度づつ回転した配置になり、等軌道傾斜角（４５度）、等近地点引数（２７０度）かつ等周期（ほぼ静止周期、２３時間５６分）であり、共通な離心率（０．０９９）が設定された３つの衛星軌道をそれぞれ周回する３機の準天頂衛星を例として説明したが、他の衛星の衛星軌道と交差する衛星軌道を有する人工衛星であれば、どのような衛星軌道を周回する人工衛星であっても本実施の形態に係る情報処理装置にて周回偏倚位置を決定することができる。
【００４９】
以上のように、本実施の形態によれば、第１の人工衛星と第２の人工衛星とが第１の保持範囲と第２の保持範囲とを重複させることなく軌道交点を通過することができる軌道面偏倚角度を第２の人工衛星の軌道面偏倚角度として決定するため、会合点における衝突を防止できるとともに、ハンドオーバ時に第１の人工衛星と第２の人工衛星とを接近させることができる。このため、地上からみたハンドオーバ時の各衛星間の距離を小さくすることができ、地上の信号送信用のアンテナが１台で済みハンドオーバ時の送信信号の遅延時間制御も容易になる。
【００５０】
実施の形態２．
本実施の形態では、実施の形態１に示した軌道面偏倚角度にて衛星軌道を周回する人工衛星及び当該人工衛星の軌道制御を行う軌道制御装置について説明する。
【００５１】
上述したように、衛星の軌道は地球偏平による重力偏向や月・太陽の引力、太陽輻射圧の影響で次第にずれてくる。軌道制御装置は、衛星までの距離を電波の往復時間で測定して衛星の位置を推定する事でこのずれる量を事前に予測する事ができる。ずれが大きくなり衛星が保持範囲から逸脱しそうになるときは軌道制御のための指示（軌道制御指示）を軌道制御装置から衛星に対して行う。
衛星では、衛星に搭載された軌道制御スラスタ即ちガスジェットを噴射することで保持範囲にとどまるよう制御する。軌道制御スラスタは定まった推力（約２２Ｎの組み合わせ）をオンオフで噴射するもので線形の推力は発生できず、衛星が保持範囲から逸脱しそうになると軌道制御装置で保持範囲に長くとどまれるような噴射方向と噴射量を計算で求め、軌道制御指示としてこれらの情報を衛星に送ってスラスタ噴射を行わせる間歇的な制御である。
このように、軌道制御装置により人工衛星の軌道制御を行うことにより、実施の形態１に示した軌道面偏倚角度にて人工衛星を周回させることができ、このため、ある会合点にて会合する２機の人工衛星を第１の人工衛星と第２の人工衛星とした場合に、第１の人工衛星と第２の人工衛星は第１の保持範囲と第２の保持範囲とを重複させることなく軌道交点を通過することができる。第１の保持範囲及び第２の保持範囲とは、実施の形態１で示した通りであり、第１の人工衛星及び第２の人工衛星がとどまるべき範囲をいう。
【００５２】
図１２は、本実施の形態に係る軌道制御装置５０の構成例を示すブロック図である。
【００５３】
衛星通信部５０１は、衛星軌道を周回する人工衛星と通信を行う。衛星通信部５０１では、衛星位置の推定のための電波の送受信及び軌道制御指示の送信を行う。
【００５４】
衛星位置推定部５０２は、衛星までの距離を電波の往復時間で測定して衛星の位置を推定する。
【００５５】
軌道情報記憶部５０３は、実施の形態１で示した情報処理装置４０の軌道情報記憶部４０８と同じ情報を記憶しており、例えば、図１に示す３機の準天頂衛星についてそれぞれの衛星の軌道情報、時刻情報、保持範囲設定情報を記憶している。
軌道情報とは各衛星が周回すべき軌道の軌跡を示す情報であり、時刻情報とは衛星軌道の各位置に衛星が到達すべき時刻を示す情報であり、保持範囲設定情報とは衛星軌道の各位置における保持範囲を示す情報である。
軌道情報記憶部５０３に記憶されている軌道情報、時刻情報、保持範囲設定情報は、実施の形態１で示した軌道面偏倚角度に対応しており、第１の人工衛星と第２の人工衛星とが第１の保持範囲と第２の保持範囲とを重複させることなく軌道交点を通過することができるようになっており、例えば、実施の形態１で示した許容偏差角度が０．１度の場合では、第１の人工衛星と軌道交点を通る子午線との間の角度が０．１４度の際に第２の人工衛星と軌道交点を通る子午線との間の角度が０．１４度より大きく１．３６度以下の角度となるようになっている。
【００５６】
制御指示部５０４は、衛星位置推定部５０２にて推定された衛星位置と軌道情報記憶部５０３に記憶された軌道情報、時刻情報、保持範囲設定情報とに基づき、衛星が保持範囲を逸脱するおそれがあるか否かを判断し、逸脱するおそれがある場合には、軌道制御スラスタの噴射方向と噴射量を計算で求め、算出した噴射方向と噴射量とを示す軌道制御指示を生成し、衛星通信部５０１を介して衛星に対して送信する。
【００５７】
図１３は軌道制御を行うための人工衛星の形態を示す。
人工衛星本体に軌道制御スラスタが複数設置されて、軌道面に垂直な方向（＋と−の両方向）に推力を発生するとともに軌道の進行方向（＋と−の両方向）に推力を発生する。衛星本体はアンテナを地球方向に向けるためと軌道制御スラスタが所定の方向に推力を発生できるように三軸安定制御が行われている。軌道制御装置５０から送信された軌道制指示に従って軌道制御スラスタを噴射することで衛星を常に保持範囲のなかにとどめておくことができる。
【００５８】
このように、本実施の形態によれば、軌道制御装置が人工衛星の位置を推定し、衛星が保持範囲を逸脱しそうな場合には軌道制御指示を送り、人工衛星で軌道制御指示に従って軌道制御を行うことにより人工衛星を保持範囲にとどめておくことが可能となり、この結果、第１の人工衛星と第２の人工衛星は第１の保持範囲と第２の保持範囲とを重複させることなく軌道交点を通過することが可能となり、会合点（軌道交点）における衝突を防止できるとともに、ハンドオーバ時に第１の人工衛星と第２の人工衛星とを接近させることができる。このため、地上からみたハンドオーバ時の各衛星間の距離を小さくすることができ、地上の信号送信用のアンテナが１台で済みハンドオーバ時の送信信号の遅延時間制御も容易になる。
【００５９】
実施の形態３．
本実施の形態では、実施の形態１及び２にて説明した人工衛星と通信を行う地上の通信装置について説明する。
【００６０】
図１４は、本実施の形態に係る通信装置を説明するための図である。
図において、衛星受信用アンテナ７０１は車輌に搭載されたアンテナであり、準天頂衛星６０から配信されるコンテンツ情報、測位情報、補正情報を受信する。
コンテンツ再生装置７０２及びカーナビゲーション装置７０３は車輌に搭載された通信装置である。コンテンツ再生装置７０２は衛星受信用アンテナ７０１を介してコンテンツ情報を受信し、コンテンツ情報の再生を行う。カーナビゲーション装置７０３は、衛星受信用アンテナ７０１を介して測位情報及び補正情報を受信し、測位情報及び補正情報を用いて車輌の所在位置を測位し、カーナビゲーションを行う。補正情報は、測位情報による測位の際に生じる誤差を補正するための情報であり、Ｄ−ＧＰＳ（Ｄｉｆｆｅｒｅｎｔｉａｌ−Ｇｌｏｂａｌ Ｐｏｓｉｔｉｏｎｉｎｇ Ｓｙｓｔｅｍ）技術等に基づき作成された情報である。
携帯端末８０１は、準天頂衛星６０から配信されるコンテンツ情報、測位情報、補正情報を受信し、コンテンツ情報の再生を行うとともに、測位情報及び補正情報を用いて携帯端末８０１のユーザの所在位置の測位を行う。
コンテンツ再生装置７０２、カーナビゲーション装置７０３、携帯端末８０１は通信装置の例に相当する。
【００６１】
コンテンツ再生装置７０２、カーナビゲーション装置７０３、携帯端末８０１が通信を行う準天頂衛星６０は、例えば、図１に示した３つの衛星軌道を周回する３機の衛星であり、上述したように、３機の準天頂衛星のうちの２機の準天頂衛星が順に約８時間ごとに会合点で会合し、コンテンツ再生装置７０２、カーナビゲーション装置７０３、携帯端末８０１は、２機の準天頂衛星が会合点にて会合する際に、通信対象となる衛星を切替える（ハンドオーバを行う）。
この切替は、準天頂衛星からの指示に従い、コンテンツ再生装置７０２、カーナビゲーション装置７０３、携帯端末８０１が行っても良い。また、コンテンツ再生装置７０２、カーナビゲーション装置７０３、携帯端末８０１が３機の準天頂衛星のうちの２機の準天頂衛星からの信号を受信したときに、コンテンツ再生装置７０２、カーナビゲーション装置７０３、携帯端末８０１が自動的に切替を行っても良い。
準天頂衛星６０は、それぞれ、実施の形態１で示した軌道面偏倚角度にて衛星軌道を周回している。コンテンツ再生装置７０２、カーナビゲーション装置７０３、携帯端末８０１がハンドオーバ前に通信を行っている衛星を第１の人工衛星とし、ハンドオーバ後に通信を行う衛星を第２の人工衛星とした場合に、第１の人工衛星と第２の人工衛星は第１の保持範囲と第２の保持範囲とを重複させることなく軌道交点を通過することができる。つまり、第１の人工衛星と第２の人工衛星とが会合点において衝突することなく衛星受信用アンテナ７０１又は携帯端末８０１のアンテナが同時に２つの衛星（第１の人工衛星と第２の人工衛星）と通信を行うことが出来る程度に接近して会合する。例えば、実施の形態１で示した許容偏差角度が０．１度の場合では、第１の人工衛星と軌道交点を通る子午線との間の角度が０．１４度の際に第２の人工衛星と軌道交点を通る子午線との間の角度が０．１４度より大きく１．３６度以下の角度となるようになっている。
準天頂衛星６０はこのように互いに接近して会合するため、コンテンツ再生装置７０２、カーナビゲーション装置７０３、携帯端末８０１は、ハンドオーバ時にそれぞれ一つのアンテナで第１の人工衛星と第２の人工衛星とを捕捉することができ、ハンドオーバ時の遅延時間制御を容易に行うことができる。
【００６２】
なお、以上では、コンテンツ再生装置、カーナビゲーション装置、携帯端末といった移動通信装置を地上での通信装置の例としたが、固定の通信装置であってもよい。
【００６３】
また、以上では、コンテンツ再生装置、カーナビゲーション装置、携帯端末はコンテンツ情報、測位情報、補正情報を受信することとしたが、これら以外の情報を受信してもよい。
【００６４】
また、以上では、準天頂衛星を例にして説明したが、地上の通信装置と通信を行う衛星が順に切替るような非静止衛星であれば準天頂衛星以外の衛星であってもよい。
【００６５】
このように、本実施の形態によれば、通信装置は、第１の保持範囲と第２の保持範囲とを重複させない程度に互いに接近して軌道交点を通過する第１の人工衛星と第２の人工衛星と通信を行うため、ハンドオーバ時に１つのアンテナで第１の人工衛星と第２の人工衛星とを捕捉することができ、ハンドオーバ時の遅延時間制御を容易に行うことができる。
【００６６】
【発明の効果】
以上のように、本発明によれば、第１の保持範囲と第２の保持範囲とを重複させることなく第１の人工衛星と第２の人工衛星とが軌道交点を通過できるようにしたため、軌道交点における衝突を回避しながら、軌道交点における第１の人工衛星と第２の人工衛星との間の距離を接近させることができる。このため、地上からみたハンドオーバ時の各衛星間の距離を小さくすることができ、地上の信号送信用のアンテナが１台で済みハンドオーバ時の送信信号の遅延時間制御も容易になる。
【図面の簡単な説明】
【図１】準天頂衛星の衛星軌道の例を示す図。
【図２】準天頂衛星の衛星軌道の例を示す図。
【図３】実施の形態１に係る情報処理装置の構成例を示す図。
【図４】第１軌道の衛星と第２軌道の衛星とが会合する際の位置関係を示す図。
【図５】第１軌道の衛星と第２軌道の衛星とが会合する際の位置関係を示す図。
【図６】第１軌道の衛星と第２軌道の衛星とが会合する際の位置関係を示す図。
【図７】軌道面偏倚角度の決定手順を示すフローチャート図。
【図８】第１軌道の衛星と第２軌道の衛星とが会合する際の位置関係を示す図。
【図９】第１軌道の衛星と第２軌道の衛星とが会合する際の位置関係を第２軌道の衛星の理想の位置とともに示す図。
【図１０】各衛星の理想の位置及び実際の位置を追加して準天頂衛星の衛星軌道の例を示す図。
【図１１】各衛星の理想の位置及び実際の位置を追加して準天頂衛星の衛星軌道の例を示す図。
【図１２】実施の形態２に係る軌道制御装置の構成例を示す図。
【図１３】実施の形態２に係る人工衛星の構成例を示す図。
【図１４】実施の形態３に係る通信装置の例を示す図。
【図１５】離心率０．０９９の導出過程を説明する図。
【図１６】離心率０．０９９の導出過程を説明する図。
【図１７】離心率０．０９９の導出過程を説明する図。
【図１８】離心率０．０９９の導出過程を説明する図。
【符号の説明】
１０ 第１軌道、２０ 第２軌道、３０ 第３軌道、４０ 情報処理装置、５０ 軌道制御装置、６０ 準天頂衛星、４０１ 入力部、４０２ 表示部、４０３ 許容偏差角度決定部、４０４ 第１の平行軌跡設定部、４０５ 第２の平行軌跡設定部、４０６ 第１の保持範囲設定部、４０７ 第２の保持範囲設定部、４０８ 軌道情報記憶部、４０９ 基準角度算出部、４１０ 軌道面偏倚角度決定部、５０１ 衛星通信部、５０２ 衛星位置推定部、５０３ 軌道情報記憶部、５０４ 制御指示部、７０１ 衛星受信用アンテナ、７０２ コンテンツ再生装置、７０３ カーナビゲーション装置、８０１ 携帯端末。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technology for determining an orbital plane deviation angle of a plurality of non-geostationary satellites whose satellite orbits intersect each other, an orbit control technology for the non-geostationary satellites, a communication technology for communicating with the non-geostationary satellites, and the like.
[0002]
[Prior art]
As a conventional technique, there are techniques disclosed in JP-A-8-223100 and JP-A-8-331033. These documents disclose a technology for communicating between a plurality of satellites such as the Iridium satellite (66) and the ground, and detect collisions between satellites for a plurality of non-geostationary satellites whose satellite orbits cross each other. A technique for shortening the inter-satellite distance when two satellites meet while avoiding them is disclosed.
[0003]
[Patent Document 1]
JP-A-8-223100
[Patent Document 2]
JP-A-8-331033
[0004]
[Problems to be solved by the invention]
In the case of an iridium satellite or the like to which the prior arts of Patent Literature 1 and Patent Literature 2 are applied, the directivity of an RF signal transmitted from the ground is low, so that communication between two satellites when transferring communication from one satellite to another satellite is performed. There is no major restriction on the distance, and there is no particular need to bring the satellites closer. In addition, although it is necessary to see multiple satellites from the ground, there are no particular restrictions and it is thought that there is sufficient flexibility in orbital arrangement, so it is possible to collide between satellites by changing the orbit of each satellite Gender does not seem to need to be considered.
For this reason, the prior arts of Patent Literature 1 and Patent Literature 2 cannot be applied to satellite communication that requires a short distance between satellites when transferring communication from one satellite to another satellite.
[0005]
SUMMARY OF THE INVENTION It is an object of the present invention to shorten the inter-satellite distance of two non-geostationary satellites whose satellite orbits intersect each other when two satellites meet while avoiding collision between the satellites.
[0006]
[Means for Solving the Problems]
The information processing device according to the present invention includes:
An information processing apparatus for determining an orbital plane deviation angle in a second satellite orbit of a second artificial satellite orbiting a second satellite orbit intersecting an orbital intersection with a first satellite orbit where the first artificial satellite orbits And
An allowable deviation angle determination unit that determines an allowable deviation range of the orbital position deviation when the first artificial satellite and the second artificial satellite orbit the satellite orbit as an allowable deviation angle;
A first holding range setting in which a region where at least a part of the outer edge is separated from the first artificial satellite by an allowable deviation angle with respect to the first satellite is set, and the region is set as a first holding range. Department and
A second holding range setting in which a region where at least a part of the outer edge is located at a position separated by an allowable deviation angle from the second satellite with respect to the second satellite is set as the second holding range Department and
The orbital plane deviation angle at which the first satellite and the second satellite can pass through the orbital intersection without overlapping the first holding range and the second holding range with the orbit of the second satellite And a raceway surface deviation angle determining unit that determines the surface deviation angle.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
An embodiment of the present invention will be described with reference to the drawings.
[0008]
In the present embodiment, an information processing apparatus that determines the orbital plane deviation angles of a plurality of non-geostationary satellites whose satellite orbits intersect each other will be described.
Here, the orbit deviation angle refers to the relative angular relationship between the orbital planes of the satellites, and other satellites that each satellite should maintain to ensure that each satellite is at a specific position at a specific time. It means the angular relationship of the orbit plane relative to the satellite.
[0009]
FIG. 1 is a diagram illustrating an example of a satellite orbit of a quasi-zenith satellite that is an example of a non-geostationary satellite to be processed by the information processing apparatus according to the first embodiment.
FIG. 1 shows three quasi-zenith satellite orbits in an inertial space centered on the earth and the movement of the satellites as viewed from the north pole of heaven. As shown in FIG. 1, the quasi-zenith satellites are three artificial satellites orbiting the first orbit 10, the second orbit 20, and the third orbit 30, respectively. The first trajectory 10 and the second trajectory meet at a point A, the second trajectory 20 and the third trajectory 30 meet at a point B, and the third trajectory 30 and the first trajectory 10 meet at a point C. A point at which a plurality of orbits meet (intersect) (points A, B, and C) is referred to as an meeting point (orbital intersection). The time required for the quasi-zenith satellite to reach the next meeting point from one meeting point is about 8 hours, and about 8 hours after the satellite in the third orbit and the satellite in the first orbit meet at the meeting point C, The satellite in the first orbit and the satellite in the second orbit meet at the meeting point A. After about 16 hours, the satellite in the second orbit and the satellite in the third orbit meet at the meeting point B. After about 24 hours, that is, one day later, the satellite in the third orbit and the satellite in the first orbit meet at point C. This repetition is continuously performed.
From the point C to the point A, the satellite in the first orbit orbiting the first orbit 10 can communicate with the ground station. After the point, the satellite communicating with the ground station switches to the satellite in the second orbit. The satellite in the second orbit can communicate with the ground station from the point A to the point B, and meets the satellite in the third orbit around the third orbit 30 at the point B, and communicates with the ground station after the point B. Is switched to the satellite in the third orbit. The satellite in the third orbit can communicate with the ground station from the point B to the point C. At the point C, the satellite in the first orbit meets the satellite in the first orbit. Switch to satellite.
[0010]
The orbital element of each satellite is expressed as follows.
The orbital major radius is about 42164 km for all three orbits, that is, a period of about 23 hours and 56 minutes, the eccentricity is about 0.099 for all three orbits, the orbital inclination angle is 45 degrees for all three orbits, and the ascending intersection RA is set at intervals of about 120 degrees. The perigee argument is 270 degrees for all three orbits, and at the same time, the near-point separation angles are 129.23 degrees, 0.0 degrees, and 230.77 degrees, respectively. The meeting point (orbital intersection) of satellites is characterized in that the trajectories of the respective orbits physically intersect, and at a certain time, two satellites physically occupy the same position at that point. This feature is provided by setting the eccentricity. If the eccentricity is set to a value different from 0.099, the trajectories of the respective orbits physically intersect, but it does not occur that two predetermined satellites occupy the same physical position at each meeting point. The eccentricity 0.099 is obtained mathematically from other defined orbital elements.
[0011]
The process of deriving the eccentricity 0.099, which is the eccentricity for two satellites to meet at the orbital meeting point and three satellites to sequentially meet at the three orbital meeting points, is shown below.
FIG. 15 shows the state of intersection of the equatorial plane with the respective orbital planes of the first and second orbits using spherical trigonometry. The equatorial plane is indicated by a disk W and its center point is indicated by O. Point O is the center of the earth. A hemispherical surface T having a common center and the same diameter is provided on a disk W, and its vertex is denoted by A (points A, B, and C shown in FIGS. 15 to 18 are meeting points A, B, and C shown in FIG. 1). Different from C). FIG. 15 is a view of the equatorial plane W and the hemisphere T as viewed from directly above, so that the points O and A appear to occupy the same position.
The line of intersection of the orbit surface of the first orbit and the hemisphere T is indicated by U. U is a semicircular arc, and the intersection with the equatorial plane W is represented by F and G. Line segment FG passes through center O. A point at which a straight line perpendicular to the line segment FG from the point O and included in the first track surface intersects the arc U is denoted by C. Obviously, the point C is the highest point of the arc U, that is, the point on the arc U farthest from the equatorial plane W.
The intersection line between the orbit surface of the second orbit and the hemisphere T is indicated by V. V is a semicircular arc, and the intersection with the equatorial plane W is represented by H and I. The line segment HI passes through the center O. The point at which a straight line perpendicular to the line segment HI from the point O and included in the second track surface intersects the arc V is denoted by D. Obviously, the point D is the highest point of the arc V, that is, the point on the arc V farthest from the equatorial plane W.
A surface obtained by rotating the first track surface clockwise by 120 degrees is a second track surface. The rotation of this plane is made about an axis perpendicular to the equatorial plane W, that is, about a straight line OA. The orbit inclination angles of the first and second orbits are angles formed by the orbital angular momentum vector (perpendicular to the orbital plane) of each orbital plane and the vertical axis of the equatorial plane W in the north direction, that is, the straight line OA, and are assumed to be equal here. The angle is represented by i. A numerical value of a specific example is i = 45 degrees.
Here, the intersection of the arc U and the arc V is B. Since the orbit inclination angles of the two orbits are equal, in FIG. 15, the arcs U and V and the points C and D are located symmetrically with respect to the arc AB. This can also be seen from the fact that the spherical triangle BIG is an isosceles triangle. This symmetry shows that the angle BAD of the spherical surface formed by the plane OBA and the plane ODA is equal to the angle BAC of the spherical surface formed by the plane OBA and the plane OCA, and the sum is 120 degrees. This can be understood from the fact that the arc U is rotated by 120 degrees to obtain the arc V, and the point C is rotated around the point A by 120 degrees to obtain the point D. Therefore, the angles BAD and BAC of the spherical surface are 60 degrees.
Further, since the plane OCA is perpendicular to the line segment FG, it is perpendicular to the plane OCF, that is, OCB. This indicates that the spherical angle ACB is a right angle. Similarly, since the plane ODA is perpendicular to the line segment HI, it is perpendicular to the plane ODH, that is, ODB. This indicates that the spherical angle ADB is a right angle.
[0012]
FIG. 16 is a diagram showing the geometric relationship shown in FIG. 15 for a first trajectory and a second trajectory. In FIG. 16, elements W and O represented by the same symbols as in FIG. 15 indicate the same as in FIG.
U ′ is a closed curve indicating the first trajectory, and an ascending intersection that crosses the equatorial plane W from south to north is G ′, and a descending intersection that crosses the equatorial plane W from north to south is F ′. The point G ′ is on the straight line OG in FIG. 15, and the point F ′ is on the straight line OF in FIG. Since the perigee argument of the first trajectory is 270 degrees, the angle from the ascending intersection point G 'to the apogee C' of the trajectory is 90 degrees, indicating that the point C 'is on the straight line OC in FIG.
V 'is a closed curve indicating the second trajectory, and an ascending intersection that crosses the equatorial plane W from north to north is H', and a descending intersection that crosses the equatorial plane W from north to south is I '. Point H 'is on line OH in FIG. 15, and point I' is on line OI in FIG. Since the perigee argument of the second trajectory is 270 degrees, the angle from the ascending intersection point H 'to the apogee D' of the trajectory is 90 degrees, which indicates that the point D 'is on the straight line OD in FIG.
Assuming that an upside line connecting the apogee C ′ and the perigee of the first trajectory U ′ is J, the straight line J is perpendicular to the straight line F′G ′ and the straight line FG, and the perigee argument is 270 degrees. Is symmetric about the straight line J. Similarly, assuming that an upside line connecting the apogee D 'and the perigee of the second orbit V' is K, the straight line K is perpendicular to the straight lines H'I 'and HI, and the perigee argument is 270 degrees. The trajectory V ′ is symmetric with respect to the straight line K. Since the first trajectory and the second trajectory are in a relationship rotated by 120 degrees around the straight line OA, the first trajectory U ′ and the second trajectory V ′ always intersect due to the symmetry of these trajectories. Assuming that an intersection on the upper side (north side) of the equator plane W is B ', the point B' is on a straight line where the orbital plane of the first orbit and the orbital plane of the second orbit intersect. This means that the point B 'is on the straight line OB in FIG. The angle B'OD 'is equal to the angle B'OC', and the angle is a.
[0013]
FIG. 17 is a diagram in which the geometric relationship centered on the spherical triangle ABD in FIG. 15 is extracted. In FIG. 17, elements A, B, D, U, and V represented by the same symbols as in FIG. 15 indicate the same as in FIG. Point E indicates the point at which the orbital angular momentum vector of the second orbit, that is, the straight line perpendicular to the orbital plane of the second orbit, intersects the hemisphere T in FIG. Since the definition of the orbit inclination angle i is the angle between the straight line perpendicular to the equatorial plane W and the orbital angular momentum vector, the angle formed by the side AE on the spherical surface is the orbit inclination angle i. Further, since the angle of the side DE is 90 degrees, if the angle of the side AD is b, the angle i of the side AE is 90 deg-b. Further, as shown in the description of FIG. 15, the angle BAD is 60 degrees and the angle ADB is 90 degrees. The angle of the side BD is a itself shown in FIG.
The spherical triangle ABD is a right-angled triangle, and the following equation is obtained from the formula of the right-angled spherical triangle.
When the angle A is the angle BAD, that is, 60 degrees, the angle a is the angle of the side BD, and the angle b is the angle of the side AD,

As a specific example, when i is 45 degrees, cos i = 1 / √2,
It can be seen that tan a = √ (3/2) and a = 50.76848 degrees.
[0014]
FIG. 18 is a diagram showing perigee, apogee, ascending intersection, descending intersection, and the meeting point with the orbit of the first satellite with respect to the second orbit. This geometric relationship holds exactly the same for the first and third trajectories. This is because the orbital planes of the three orbitals are separated from each other by 120 degrees around the vertical of the equatorial plane, and the orbital long radius, that is, the orbital period, the eccentricity, the orbital inclination angle, and the perigee argument are respectively equal. In FIG. 18, the elements O, B ', D', H ', I', and a represented by the same symbols as in FIGS. 15 and 16 are the same as those in FIGS. Point L indicates the perigee of the trajectory, and point M indicates the meeting point with the next trajectory. The point M is located symmetrically with the point B 'with respect to the inside line D'L. The angle f is an angle formed from the perigee L to the point B ′ and is an angle called a right near point departure.
When three satellites sequentially meet at the meeting point, when viewed in the second orbit, the satellite in the first orbit and the satellite in the second orbit meet at point B ', and then the satellite in the first orbit. , When the satellite in the second orbit arrives at the meeting point M via the apogee D 'and the satellite in the third orbit appears at the point M and meets there, repeating the event sequentially for every three satellites Point to. Therefore, in order for this event to occur, the time from the meeting point B 'to the next meeting point M should be one-third of the orbital period. On the other hand, if it is different from one-third, the meetings do not occur sequentially.
In FIG. 18, the required time from perigee L to apogee D 'is equal to the required time from apogee D' to perigee L, and is one half of the orbital period. The required time from point B 'to point D' is equal to the required time from point D 'to point M and is one sixth of the orbital period. The required time from point L to point B 'is equal to the required time from point M to point L, and is one third of the orbital period. Thus, a typical example of the arrangement of three satellites for meeting is a case where the satellites are at points B ′, M and L in each orbit at a certain point in time.
The orbital radius, eccentricity, orbital inclination, and perigee argument are equal in three orbits, and the values of the orbital radius and orbital inclination are given. The perigee argument is 270 degrees. When they are separated by 120 degrees around, that is, the ascending intersections are separated by 120 degrees, the time required from the meeting point B 'to the next meeting point M becomes one-third of the orbital period. The required time from L to the meeting point B 'may be one-third of the orbital period, and the eccentricity at which it is satisfied has a specific value. The method of obtaining the eccentricity will be described below.
Since the required time from perigee L to meeting point B 'is one-third of the orbital period, the average perigee separation m of point B' is
m = (2 × π) / 3
It is. This is because the orbital period represented by the average perigee separation is 2 × π.
The following equation is well known as a relational expression between the average near-point separation m, the eccentric near-point separation g, and the true near-point separation f.
tan (f / 2)
= √ ((1 + e) / (1-e)) × tan (g / 2)
m = g−ex × sing
Here, e is the eccentricity to be obtained.
The near-point separation angle f is expressed as follows using the angle a.
f = π-a
[0015]
In summary, the angle a is obtained from the orbit inclination angle i, the near-point separation angle f is obtained from a, and e is obtained from f and m. As can be seen from these equations, the equation for obtaining e from f and m is a transcendental equation and cannot be directly obtained analytically, but is obtained by numerical calculation such as an iterative method.
As a specific example, when i = 45 degrees, a = 50.76848 degrees, and it can be seen from the numerical calculation that e = 0.099.
[0016]
As described above, the quasi-zenith satellite, which is an example of the non-geostationary satellite to be processed by the information processing apparatus according to the present embodiment, has ascending right ascensions different by almost 120 degrees, that is, the orbital plane has been rotated by almost 120 degrees. In the three satellite orbits of equidistant orbit inclination angle (45 degrees), equal perigee argument (270 degrees) and equal period (almost stationary period, 23 hours and 56 minutes), satellites flying in each orbit are An eccentricity (0.099) common to the three orbits is set so that the orbits meet at the junction of the orbits.
[0017]
FIG. 2 shows the trajectory of the point directly below the satellite on the ground.
The trajectory is in the form of an asymmetric figure eight, and the intersection of the figure eight indicates the meeting point itself in FIG. Although three orbits are shown in FIG. 1, by setting those orbital elements as described above, the ground surface locus at a point directly below the satellite becomes one figure of eight. When each satellite is located at apogee or perigee, the longitude of the point directly below it is 135 degrees east longitude, and when the satellite travels from the meeting point to the next meeting point via apogee, the trajectory of that point immediately starts at the intersection of figure eight. It will return to the intersection of the figure eight again through the point directly below the satellite at 45 degrees north latitude and 135 degrees east longitude. During this period (approximately 8 hours), the satellite stays over Japan, the elevation angle when viewing the satellite from Japan is about 70 degrees or more, and the possibility of entering the shadows of mountains and buildings is lower than that of ordinary geostationary satellites. Become.
When two satellites meet at the meeting point, for example, when the satellite in the third orbit and the satellite in the first orbit meet at the point C (the satellite to be communicated by the ground station is the In the case of switching to a satellite in one orbit), the signal transmitted to the satellite is transmitted from the antenna of the ground station to the satellite in the third orbit, where the signal transmitted to the satellite is the satellite in the first orbit. The transmission to the satellite in the first orbit is started at a frequency different from that for the satellite in the third orbit so as to be transmitted to the third orbit. When the switching process in the ground station is completed, the transmission to the satellite in the third orbit is stopped, and the satellite in the first orbit continues to be in charge of communication with the ground.
Here, when the satellites in the third orbit and the satellites in the first orbit meet, the ground station simultaneously transmits the two satellites with the same antenna without collision between the satellite in the third orbit and the satellite in the first orbit. It is desirable to be close enough to send out the signal.
For this reason, in the information processing apparatus according to the present embodiment, when two satellites meet, the two satellites can simultaneously transmit signals to the two satellites with the same antenna of the ground station without collision. The position relationship of each satellite is determined so that the satellites will approach each other.
[0018]
FIG. 3 is a block diagram illustrating a configuration example of the information processing apparatus 40 according to the present embodiment.
[0019]
The input unit 401 inputs various instructions from an operator.
The display unit 402 displays a processing result of the information processing device 40 on a display.
[0020]
The allowable deviation angle determination unit 403 determines an allowable deviation angle that is an allowable deviation range of the orbital position deviation when each satellite orbits each satellite orbit. The allowable deviation angle is an angle from the position of the satellite with respect to the center of the earth to the allowable deviation.
[0021]
The first parallel trajectory setting unit 404 determines a reference satellite (hereinafter, referred to as a first artificial satellite) when determining an orbital plane deviation angle of a satellite to be determined an orbital plane deviation angle (hereinafter, referred to as a second artificial satellite). A parallel trajectory (first parallel trajectory) parallel to the satellite orbit of the first satellite is set at a position separated from the satellite orbit of the satellite by an allowable deviation angle. Here, in this specification, parallel means that the satellite orbit is running parallel to the satellite orbit at a constant interval, and parallel orbit is a satellite orbit while maintaining a position separated from the satellite orbit by an allowable deviation angle. A trajectory that runs parallel to The satellite orbit is composed of curved lines, and a trajectory running parallel to the satellite orbit is called a parallel trajectory.
FIG. 4 shows an example in which the satellite in the first orbit is a first artificial satellite and the satellite in the second orbit is a second artificial satellite. It is a parallel trajectory parallel to one orbit 10 and a first parallel trajectory.
[0022]
The second parallel trajectory setting unit 405 sets a parallel trajectory (second parallel trajectory) parallel to the satellite orbit of the second artificial satellite at a position separated from the satellite orbit of the second artificial satellite by an allowable deviation angle. . Similarly, in FIG. 4, reference numeral 23 denotes a parallel trajectory parallel to the second trajectory 20 separated from the second trajectory 20 by an allowable deviation angle, and is a second parallel trajectory.
[0023]
The first holding range setting unit 406 sets a first holding range around the first artificial satellite.
The first holding range is a range in which the first artificial satellite should stay, and refers to a rectangle having two sides on the first parallel locus with the first artificial satellite as the center.
The orbit of the satellite gradually shifts due to the effects of gravity deflection due to the Earth's flattening, the attraction of the moon and the sun, and the solar radiation pressure. In the meantime, the satellite corrects the orbit by injecting an orbit control thruster or gas jet.
By keeping the satellites in this holding range at all times, the communication antenna can be accurately oriented in a predetermined ground direction, and it is possible to avoid radio wave interference and physical collision with other satellites. Become.
Reference numeral 14 in FIG. 4 indicates a holding range of the satellite in the first orbit as the first artificial satellite, that is, a first holding range. In FIG. 4, the first holding range 14 is a square in which the distance from the satellite position 11 in the first orbit to each side is separated by an allowable deviation angle.
It is not necessary to provide a holding range in the earth direction.
[0024]
The second holding range setting unit 407 sets a second holding range around the second artificial satellite.
The second holding range is a range where the second artificial satellite should stay, and refers to a rectangle whose two sides are on the second parallel locus with the second artificial satellite as the center.
Reference numeral 24 in FIG. 4 indicates the holding range of the satellite in the second orbit, which is the second artificial satellite, that is, the second holding range. In FIG. 4, the second holding range 24 is a square in which the distance from the satellite position 22 in the second orbit to each side is separated by an allowable deviation angle. It is not necessary to provide a holding range in the earth direction.
[0025]
The orbit information storage unit 408 stores the orbit information of each satellite. Orbit information is information indicating the trajectory of the orbit that each satellite should orbit.
[0026]
The reference angle calculation unit 409 calculates a reference angle serving as a reference when determining the orbital plane deviation angle of the second artificial satellite. Details of the reference angle will be described later.
[0027]
The orbital plane deviation angle determination unit 410 determines the orbital plane deviation angle of the first artificial satellite and determines the orbital plane deviation angle of the second artificial satellite based on the orbital plane deviation angle of the first artificial satellite.
[0028]
Next, the principle of determining the orbital plane deviation angle in the information processing device 40 according to the present embodiment will be described.
FIG. 5 is a diagram for explaining the principle of determining the raceway surface deviation angle.
FIG. 5 shows an example in which the satellite in the first orbit is a first artificial satellite and the satellite in the second orbit is a second artificial satellite. The ascending intersection of the right ascension differs by 120 degrees, that is, the orbital plane is rotated by 120 degrees, the equi-orbit inclination angle (45 degrees), the isopia argument (270 degrees) and the equal cycle (almost stationary cycle, 23 hours 56 hours) In three satellite orbits where the common eccentricity (0.099) is set for the three orbits in (min), it is already possible that the satellites flying in each orbit can be arranged to meet at the meeting point of each orbit. Stated. However, encounters at the meeting point must be avoided because of the possibility of a satellite collision. For this reason, the orbit arranged so that satellites flying in three orbits meet at the meeting point of each orbit, and slightly rotate the orbit plane of the second orbit around the axis perpendicular to the equatorial plane and passing through the center of the earth. . Reference numeral 26 in FIG. 5 shows the second trajectory before the rotational movement. The point after the rotational movement of the point A with respect to the meeting point A of the second trajectory before the rotational movement is referred to as the meeting point AA. Further, when referred to as the second trajectory, the second trajectory after the rotational movement is referred to. In FIG. 5, the satellite in the first orbit is at the position of the meeting point A, and the satellite in the second orbit is at the position of the meeting point AA. At the point where the parallel trajectory above the first parallel trajectory 13 and the parallel trajectory above the second parallel trajectory 23 intersect (parallel trajectory intersection), the upper right of the holding range 14 of the satellite in the first orbit. And the upper left vertex of the holding range 24 of the satellite in the second orbit overlaps. In this situation, the satellite in the first orbit and the satellite in the second orbit may collide at the overlapping point of the holding range, but the holding range 14 of the satellite in the first orbit and the holding range of the satellite in the second orbit. As described above, by slightly rotating the orbital plane of the second orbit about the axis perpendicular to the equatorial plane and passing through the center of the earth, the position between the two satellites in FIG. Because of the increased lateral spacing, there is no risk of collision between the two satellites. FIG. 4 shows the positional relationship between the two satellites immediately before the state shown in FIG. 5 (the satellite in the second orbit is in front of the meeting point AA). And the holding range 24 of the satellite in the second orbit do not overlap, and there is no danger of collision. FIG. 6 shows the positional relationship between the two satellites immediately after the state shown in FIG. 5 (the state in which the satellite in the first orbit has passed point A). And the holding range 24 of the satellite in the second orbit do not overlap, and there is no danger of collision.
Thus, there is a risk of collision between the two satellites when the two satellites have the positional relationship shown in FIG. 5, and the orbital plane of the satellite in the second orbit is perpendicular to the equatorial plane from the positional relationship shown in FIG. By slightly rotating about the axis passing through the center of the earth at, the lateral distance between the two satellites increases, and there is no danger of collision between the two satellites. In other words, when the upper right vertex of the first holding range 14 is on the intersection (parallel locus intersection) of the first parallel locus and the second parallel locus, the upper left vertex of the second holding range 24 If the vertex has already passed through the parallel locus intersection, the two holding ranges do not overlap, and there is no danger of collision between the two satellites.
This is because the angle of the meridian passing from the satellite in the first orbit to the meeting point A when the upper right vertex of the first holding range 14 overlaps the parallel locus intersection is smaller than the satellite in the second orbit to the meeting point A. If the angle of the meridian passing through is larger, both holding ranges do not overlap, meaning that there is no risk of collision between the two satellites.
[0029]
For this reason, the information processing device 40 according to the present embodiment is configured such that the angle of the meridian passing from the satellite in the second orbit to the point A of the meeting point when the upper right vertex of the first holding range 14 overlaps the parallel locus intersection is changed. The orbit deviation angle of the satellite in the second orbit is determined so as to be larger than the angle of the meridian passing from the satellite in the first orbit to the point of association A.
The position of the first artificial satellite when the lower right vertex of the first holding range 14 is inside the second parallel locus and the upper right vertex overlaps the parallel locus intersection is referred to as a reference position. For example, the satellite in the first orbit shown in FIG. 5 is at the reference position.
[0030]
Next, the procedure for determining the orbital plane deviation angle of the information processing apparatus 40 according to the present embodiment will be described with reference to the flowchart of FIG.
First, in step S701, a first artificial satellite and a second artificial satellite are determined. The input unit 401 instructs an operator from the satellite in the first orbit, the satellite in the second orbit, and the satellite in the third orbit shown in FIG. 1 as the first artificial satellite and the second artificial satellite. According to the input, the orbit deviation angle determination unit 410 determines the satellite to be the first artificial satellite and the satellite to be the second artificial satellite according to the input result from the input unit 401.
[0031]
Next, in step S702, an allowable deviation range is determined. The input unit 401 inputs the value of the allowable deviation angle from the operator, and the allowable deviation angle determination unit 403 determines and stores the input value as the allowable deviation angle.
Next, in step S703, a first parallel locus and a second parallel locus are set. A first parallel locus setting unit 404 and a second parallel locus setting unit 405 set a first parallel locus and a second parallel locus, respectively. Specifically, the first parallel trajectory setting unit 404 reads the orbit information of the first artificial satellite from the orbit information storage unit 408, and performs the first artificial trajectory based on the allowable deviation angle determined by the allowable deviation angle determination unit 403. Two parallel trajectories are set at positions separated from the satellite orbit of the satellite (hereinafter, referred to as a first satellite orbit) by an allowable deviation angle. Further, the second parallel trajectory setting unit 404 reads the orbit information of the second artificial satellite from the orbit information storage unit 408, and based on the allowable deviation angle determined by the allowable deviation angle determining unit 403, the satellite of the second artificial satellite. Two parallel trajectories are set at positions separated from the orbit (hereinafter, referred to as a second satellite orbit) by an allowable deviation angle.
[0032]
Next, in step S704, the orbit deviation angle of the first artificial satellite is determined. The input unit 401 inputs the orbital plane deviation angle of the first artificial satellite from the operator, and the orbital information storage unit 408 stores the orbital plane deviation angle of the first artificial satellite after the processing by the orbital plane deviation angle determination unit 410. . Specifically, the operator inputs the specific position, for example, the time at which the first artificial satellite should reach the meeting point with the second artificial satellite, and the orbital plane deviation angle determination unit 410 receives the input from the operator. The arrival time is calculated for each position on the first satellite orbit based on the time, and is stored in the orbit information storage unit 408 as first arrival time information.
[0033]
Next, in step S705, a first holding range is set. The first holding range setting unit 406 reads the orbit information of the first artificial satellite stored in the orbit information storage unit 408, sets a first holding range for each position on the first satellite orbit, The trajectory information storage unit 408 stores the storage range setting information 1 as the storage range setting information.
[0034]
Next, in step S706, the reference position of the first artificial satellite and its time (reference time) are specified. The orbital plane deviation angle determination unit 410 determines the reference position of the first artificial satellite based on the orbital information of the first artificial satellite, the first arrival time information, and the first holding range setting information stored in the orbital information. That is, as shown in FIG. 5, the position of the first artificial satellite when the upper right vertex of the holding range of the first artificial satellite overlaps the parallel locus intersection is specified. The time of reaching the position is specified as the reference time.
[0035]
Next, in step S707, the angle (reference angle) between the reference position of the first artificial satellite and the meridian passing through the meeting point is calculated. The reference angle calculation unit 409 calculates an angle between the reference position of the first artificial satellite specified in step S706 and a meridian passing through the meeting point, and sets the angle as a reference angle.
[0036]
Next, in step S708, a position separated from the meridian passing through the meeting point by a reference angle or more is set as the position of the second artificial satellite at the reference time, and the orbital plane deviation angle of the second artificial satellite is determined. The orbital plane deviation angle determination unit 410 specifies a position on the second satellite orbit separated by an angle equal to or more than the reference angle from the meridian passing through the meeting point, and determines the position on the second satellite orbit at the second time at the reference time. Satellite position. That is, at the reference time, the first artificial satellite is located at a position separated from the meridian passing through the meeting point by a reference angle (= reference position), and the second artificial satellite is separated from the meridian passing through the meeting point by more than the reference angle. To be in place. Based on the position of the second artificial satellite at the reference time thus determined, the arrival time of the second artificial satellite is calculated for each position of the second satellite orbit, and the orbit information storage unit is used as the second arrival time information. 408 is stored.
[0037]
Next, in step S709, the holding range of the second artificial satellite is set. The second holding range setting unit 407 reads the orbit information of the second artificial satellite stored in the orbit information storage unit 408, sets the second holding range for each position on the second satellite orbit, and sets the second holding range. Is stored in the trajectory information storage unit 408 as the holding range setting information.
[0038]
By determining the orbital plane deviation angle of the second artificial satellite as described above, the first artificial satellite and the second artificial satellite do not overlap the first holding range and the second holding range. Each can pass through the meeting point, and the danger of collision between the first satellite and the second satellite can be avoided.
[0039]
For example, when the satellite in the first orbit in FIG. 1 is the first artificial satellite and the satellite in the second orbit is the second artificial satellite and the orbital plane deviation angle of the satellite in the second orbit is determined, the second orbit The satellite of the third orbit is determined as the first artificial satellite, the satellite of the third orbit is defined as the second artificial satellite, and processing is performed in accordance with the procedure shown in FIG. . However, since the allowable deviation angle, the orbital plane deviation angle of the satellite in the second orbit, and the holding range of the satellite in the second orbit have already been determined, steps S702 to S705 are omitted.
[0040]
Also, contrary to the above description, the satellite in the second orbit in FIG. 5 is set as the first artificial satellite, the satellite in the first orbit is set as the second artificial satellite, and the satellite in the second orbit is determined based on the position of the satellite in the second orbit. When determining the orbital plane deviation angle of the satellite in the first orbit, the position of the satellite in the second orbit shown in FIG. 5 (the lower left vertex of the holding range of the satellite in the second orbit is parallel to the satellite in the first orbit). (The position of the satellite in the second orbit when the upper left vertex is in contact with the intersection of the parallel orbits inside the trajectory) as the reference position, and the satellite in the second orbit and the meeting point when the satellite in the second orbit is at the reference position The angle between the meridian passing through point A is defined as a reference angle.
[0041]
Next, the procedure for determining the orbital plane deviation angle of the second artificial satellite will be described using specific numerical values.
Hereinafter, a case where the allowable deviation angle is set to 0.1 degree will be described as an example.
FIG. 8 shows the same state as the state shown in FIG. 5, but for convenience of explanation, the positions of the satellites in the first orbit and the satellites in the second orbit are omitted, and the first holding range and the second holding Only the range is displayed. FIG. 8 specifically shows the intersection angle between the first trajectory and the second trajectory. In addition, as described above, since the allowable deviation angle is set to 0.1 degree in this example, the angle from the first trajectory to the first parallel trajectory is 0.1 degree, and the angle from the second trajectory to the second parallel trajectory is set. Is also 0.1 degree. The angle from the satellite in the first orbit to each side of the first holding range is 0.1 degree, and the angle corresponding to the length of each side of the first holding range is 0.2 degree. I have. The same applies to the second holding range. The angle from the satellite in the second orbit to each side of the second holding range is 0.1 degree, which is equivalent to the length of each side of the second holding range. The angle is 0.2 degrees.
In the description below, the satellite in the first orbit will be described as an example of the first artificial satellite, and the satellite in the second orbit will be described as an example of the second artificial satellite.
[0042]
In FIG. 8, the holding ranges are in contact at point X (the satellite in the first orbit is at the reference position). Point X is a parallel locus intersection point where the parallel locus above the first parallel locus and the parallel locus above the second parallel locus intersect. Point Z is a trajectory intersection where the first trajectory and the second trajectory intersect. Point Y is a point where the front side of the first holding range and the first track overlap.
When the spherical triangle ZXY is picked up, the interior angle Y is 90 degrees because the point Y is on the side of the first holding range. Since the first trajectory and the second trajectory take the trajectory elements shown in FIG. 1, the angles formed by these two trajectories are 104.478 degrees and 75.522 degrees, and the interior angle Z is a half of 104.478 degrees. 1 is 52.239 degrees. Further, since the first holding range is a square of +/− 0.1 degrees, the side z (side angle opposing the angle Z) is 0.1 degrees.
From the formula of a right-angled spherical triangle, the side x (side angle opposite the angle X) is expressed as follows:
sin x = tan z / tan Z
When the side x is obtained using the above numerical values, it is 0.077 degrees.
Since the angle from the center position of the first holding range (= point A of the satellite in the first orbit) to each side of the first holding range is 0.1 degree, the center position of the first holding range ( = The angle from the first orbit satellite position A) to point Z is 0.077 + 0.1 = 0.177 degrees. Here, from the symmetry in FIG. 8, the line segment connecting the points A and AA is orthogonal to the meridian passing through the points X and Z. This intersection is defined as point U. In the spherical triangle AZU, the interior angle U is 90 degrees, and the angle u (side angle opposite the angle U) is 0.177 degrees as described above. The interior angle Z is 52.239 degrees, which is one half of 104.478 degrees.
From the formula of a right-angled spherical triangle, the side z (side angle opposite the angle Z) is expressed as:
tan z = cos A · tan u, cos u = cot A · cot Z
When the side z is obtained using the above numerical values, it is 0.140 degrees.
This 0.140 degree corresponds to the reference angle (the angle from the point A to the meridian passing through the orbit intersection Z point, that is, the angle between the points A and U). Further, in FIG. 8, since the geometric relationship is symmetrical in the vertical and horizontal directions of the figure, the angle from the point Z to the center position of the second holding range (= the position AA of the satellite in the second orbit) is also changed. Similarly, it becomes 0.140 degrees. In FIG. 8, since the first holding range and the second holding range overlap at the point X, the second holding range is set so that the orbit plane of the second orbit passes around the axis passing through the center of gravity perpendicular to the equatorial plane. If it is rotated and shifted in the east-west direction, the first holding range and the second holding range do not overlap. Therefore, when the angle between the satellite in the first orbit and the meridian passing through the orbital intersection Z point is 0.140 degrees, the satellite in the second orbit is larger than 0.140 degrees from the meridian passing through the orbital intersection Z point. When the satellites in the first orbit and the satellites in the second orbit are arranged at an angle apart, the satellite in the first orbit and the satellite in the second orbit can pass through the orbit intersection Z point without overlapping the first and second holding ranges. .
[0043]
Regarding the maximum value of the angle between the satellite in the second orbit and the meridian passing through the orbital intersection point Z, the beam width of the 45 cm diameter parabolic antenna using the Ku band is 3 degrees (pp). When the center of the parabolic antenna points to one satellite during handover, the same antenna can cover two satellites if the other satellites are separated from each other by 1.5 degrees or less. Therefore, in order to cover two satellites with one user antenna at the time of handover, it is considered appropriate to set the upper limit of the separation angle of the two satellites to 1.5 degrees. Since the angle between the satellite in the first orbit and the meridian passing through the orbital intersection Z point is 0.140 degrees, the angle between the meridian passing through the orbital intersection Z point and the satellite in the second orbit is 1.5-0.140. It is appropriate that the upper limit is 1.360 degrees.
[0044]
As described above, when the allowable deviation angle is set to 0.1 degree, the reference angle is set to 0.14 degrees, and the angle between the first artificial satellite and the meridian passing through the orbital intersection becomes 0.14 degrees. Orbit angle of the second satellite such that the angle between the second satellite and the meridian passing through the orbital intersection is greater than 0.14 degrees and less than or equal to 1.36 degrees. To determine. Since the latitude of the orbital intersection is approximately 26.57 degrees, the difference between the satellite orbit of the first artificial satellite and the ascension of each ascending intersection of the second artificial satellite is at least 0.31 degrees and 1.68 by spherical trigonometry. Degrees or less.
[0045]
FIG. 9 is a diagram in which the ideal position 21 of the satellite in the second orbit is added to FIG. The ideal position of the satellite in the second orbit is the position of the satellite in the second orbit 26 before reaching the meeting point A at the same time as the satellite in the first orbit.
When the satellite in the second orbit reaches the meeting point A simultaneously with the satellite in the first orbit, the angle between the ideal position of the satellite in the second orbit and the meridian passing through the orbital intersection point Z is obtained. Is equal to the angle between the satellite position 11 in the first orbit and the meridian passing through the orbital intersection Z, which is 0.14 degrees.
Therefore, in FIG. 9, since the geometric relationship is symmetrical in the vertical and horizontal directions in the figure, the ideal position 21 of the satellite in the second orbit and the position 22 of the satellite in the second orbit (the first holding range and the first 2 (a position where the holding range of 2 overlaps at the intersection of the parallel orbits) is 0.28 degrees, which is twice 0.14 degrees. For this reason, if the separation angle of the second holding range, more precisely, the separation angle between the ideal position 21 of the satellite in the second orbit and the center position of the second holding range is 0.28 degrees, the first orbit will be changed. It can be seen that collision between two satellites, the satellite of the second orbit and the satellite of the second orbit, is prevented. That is, 0.28 degrees is the minimum value for preventing collision, and may be 0.28 degrees or more. The maximum value only needs to be in a range that can be complemented by two satellites at a time as viewed from the terminal on the ground.
[0046]
FIG. 10 is a diagram in which the ideal position and the actual position of each satellite are added to FIG. 1, and FIG. 11 is a diagram in which the ideal position and the actual position of each satellite are added to FIG.
FIG. 10 shows a situation when the satellite in the first orbit reaches the meeting point C. The actual satellite position of the satellite 11 in the first orbit coincides with the ideal position. The ideal position 31 of the satellite in the third orbit coincides with the actual position 11 of the satellite in the first orbit. As described above, at the ideal positions, the respective ideal positions coincide with each other at the meeting points A, B, and C. Among the orbital elements, the near-point separation angles of the ideal satellite positions are 129.23 degrees, 0 degrees, and 230.77 degrees, respectively.
Then, as described above, in order to eliminate the possibility of collision between satellites, the actual satellite positions in the second and third orbits are positively shifted from the ideal satellite positions by +/- 0.28. Each orbit is shifted about an axis perpendicular to the equatorial plane and passing through the center of the earth. In the second orbit, the actual position 25 of the satellite in the second orbit is the position obtained by rotating the orbital plane containing the satellite 0.28 degrees from the ideal position 21 about an axis perpendicular to the equatorial plane and passing through the center of the earth. In the third orbit, the actual position 35 of the satellite in the third orbit is -0.28 degrees from the ideal position 32, rotating the orbital plane containing the satellite about an axis perpendicular to the equatorial plane and passing through the center of the earth. And position.
In FIG. 11, the satellite in the first orbit is just above the intersection and ascending from the south, and the satellite in the third orbit is descending from the north toward the intersection. The signal transmitted to the satellite is sent from the antenna of the ground station to the satellite in the third orbit, where the signal transmitted to the satellite is also transmitted to the satellite in the first orbit. Transmission to the satellite in the first orbit at a frequency different from that of. At this time, since the satellite in the third orbit and the satellite in the first orbit are close to each other, it is possible to simultaneously transmit signals to the two satellites with the same antenna. Further, since the distance between the antenna of the ground station and each satellite is almost the same, it is easy to control the delay time of the transmission signal required at the time of signal switching. Thereafter, the transmission to the satellite in the third orbit is stopped, and the satellite in the first orbit continues to be in charge of communication with the ground.
[0047]
As described above, when the allowable deviation angle is set to 0.1 degree, the positions obtained by rotating the satellites in the second orbit and the satellites in the third orbit by 0.28 degrees from the ideal satellite positions are regarded as the actual positions. Then, even when two satellites meet, they can meet without overlapping their holding ranges, and the possibility of collision can be avoided.
[0048]
In the above description, the satellite orbiting the satellite orbit shown in FIG. 1, that is, the ascending intersection RA is different by approximately 120 degrees, that is, the orbital plane is rotated by approximately 120 degrees, and the equi-orbit inclination angle (45 Degrees), equi-perigee argument (270 degrees) and equi-period (almost stationary cycle, 23 hours 56 minutes), and three satellites orbiting three satellite orbits with a common eccentricity (0.099), respectively. Although the quasi-zenith satellite has been described as an example, any artificial satellite that orbits any satellite orbit as long as it has a satellite orbit that intersects with the satellite orbit of other satellites, according to the present embodiment. The orbital deviation position can be determined by the processing device.
[0049]
As described above, according to the present embodiment, it is possible for the first artificial satellite and the second artificial satellite to pass through the orbit intersection without overlapping the first holding range and the second holding range. Since the possible orbital plane deviation angle is determined as the orbital plane deviation angle of the second artificial satellite, collision at the meeting point can be prevented and the first artificial satellite and the second artificial satellite can be approached at the time of handover. . For this reason, the distance between the satellites at the time of handover from the ground can be reduced, and only one antenna for signal transmission on the ground is required, so that the control of the delay time of the transmission signal at the time of handover becomes easy.
[0050]
Embodiment 2 FIG.
In the present embodiment, an artificial satellite orbiting a satellite orbit at the orbital plane deviation angle shown in the first embodiment and an orbit control device for controlling the orbit of the artificial satellite will be described.
[0051]
As described above, the orbit of a satellite gradually shifts due to the influence of gravity deflection due to the Earth's flattening, the attraction of the moon and the sun, and the solar radiation pressure. The orbit control device can predict the amount of the deviation in advance by measuring the distance to the satellite by the round-trip time of the radio wave and estimating the position of the satellite. When the deviation increases and the satellite is likely to deviate from the holding range, an orbit control instruction (orbit control instruction) is issued from the orbit control device to the satellite.
In a satellite, an orbit control thruster mounted on the satellite, that is, a gas jet is injected to control the satellite so that it stays within the holding range. The orbit control thruster injects a fixed thrust (combination of about 22N) on and off and cannot generate a linear thrust, and when the satellite is about to deviate from the holding range, the orbit control device will stay in the holding range for a long time. This is an intermittent control in which a direction and an injection amount are calculated, and these information is sent to a satellite as an orbit control instruction to perform a thruster injection.
As described above, by controlling the orbit of the artificial satellite by the orbit control device, the artificial satellite can orbit at the orbital plane deviation angle shown in the first embodiment, and therefore, meet at a certain meeting point. When the two artificial satellites are a first artificial satellite and a second artificial satellite, the first artificial satellite and the second artificial satellite overlap the first holding range and the second holding range. Without passing through the orbital intersection. The first holding range and the second holding range are as described in Embodiment 1, and refer to the range in which the first artificial satellite and the second artificial satellite should stay.
[0052]
FIG. 12 is a block diagram illustrating a configuration example of the trajectory control device 50 according to the present embodiment.
[0053]
The satellite communication unit 501 communicates with an artificial satellite orbiting a satellite orbit. The satellite communication unit 501 transmits and receives radio waves for estimating a satellite position and transmits an orbit control instruction.
[0054]
The satellite position estimation unit 502 estimates the position of the satellite by measuring the distance to the satellite based on the round-trip time of the radio wave.
[0055]
The orbital information storage unit 503 stores the same information as the orbital information storage unit 408 of the information processing device 40 described in the first embodiment. For example, the three quasi-zenith satellites shown in FIG. Orbit information, time information, and holding range setting information are stored.
The orbit information is information indicating the trajectory of the orbit that each satellite should orbit, the time information is information indicating the time at which the satellite should reach each position in the satellite orbit, and the holding range setting information is the information of the satellite orbit. This is information indicating a holding range at each position.
The orbital information, time information, and holding range setting information stored in the orbital information storage unit 503 correspond to the orbital plane deviation angle described in the first embodiment, and the first artificial satellite and the second artificial satellite Can pass through the orbit intersection without overlapping the first holding range and the second holding range. For example, the allowable deviation angle shown in the first embodiment is 0.1 degree. In the case of the above, when the angle between the first satellite and the meridian passing through the orbital intersection is 0.14 degrees, the angle between the second satellite and the meridian passing through the orbital intersection is more than 0.14 degrees. The angle is largely 1.36 degrees or less.
[0056]
The control instruction unit 504 may cause the satellite to deviate from the holding range based on the satellite position estimated by the satellite position estimating unit 502 and the orbit information, time information, and holding range setting information stored in the orbit information storage unit 503. It is determined whether or not there is a deviation, and if there is a possibility of departure, the injection direction and injection amount of the orbit control thruster are calculated, the orbit control instruction indicating the calculated injection direction and injection amount is generated, and the satellite The data is transmitted to the satellite via the communication unit 501.
[0057]
FIG. 13 shows a form of an artificial satellite for orbit control.
A plurality of orbit control thrusters are installed on the satellite body, and generate thrust in a direction perpendicular to the orbit plane (in both directions of + and-) and generate thrust in the traveling direction of the orbit (in both directions of + and-). The three-axis stability control is performed on the satellite main body so that the antenna is directed toward the earth and the orbit control thruster can generate a thrust in a predetermined direction. By injecting the orbit control thruster in accordance with the orbit control instruction transmitted from the orbit control device 50, the satellite can always be kept within the holding range.
[0058]
As described above, according to the present embodiment, the orbit control device estimates the position of the artificial satellite, sends an orbit control instruction when the satellite is likely to deviate from the holding range, and controls the orbit according to the orbit control instruction with the artificial satellite. Is performed, it is possible to keep the artificial satellite in the holding range, and as a result, the first artificial satellite and the second artificial satellite do not overlap the first holding range and the second holding range. It is possible to pass through the orbital intersection, thereby preventing a collision at the meeting point (orbital intersection) and allowing the first artificial satellite and the second artificial satellite to approach each other at the time of handover. For this reason, the distance between the satellites at the time of handover from the ground can be reduced, and only one antenna for signal transmission on the ground is required, so that the control of the delay time of the transmission signal at the time of handover becomes easy.
[0059]
Embodiment 3 FIG.
In the present embodiment, a terrestrial communication device that communicates with the artificial satellite described in Embodiments 1 and 2 will be described.
[0060]
FIG. 14 is a diagram for explaining the communication device according to the present embodiment.
In the figure, a satellite receiving antenna 701 is an antenna mounted on a vehicle, and receives content information, positioning information, and correction information distributed from the quasi-zenith satellite 60.
The content reproduction device 702 and the car navigation device 703 are communication devices mounted on a vehicle. The content reproduction device 702 receives the content information via the satellite reception antenna 701 and reproduces the content information. The car navigation device 703 receives the positioning information and the correction information via the satellite reception antenna 701, and uses the positioning information and the correction information to determine the position of the vehicle, and performs the car navigation. The correction information is information for correcting an error generated at the time of positioning based on the positioning information, and is information created based on D-GPS (Differential-Global Positioning System) technology or the like.
The mobile terminal 801 receives the content information, positioning information, and correction information distributed from the quasi-zenith satellite 60, reproduces the content information, and uses the positioning information and the correction information to determine the location of the user of the mobile terminal 801. Perform positioning.
The content reproducing device 702, the car navigation device 703, and the portable terminal 801 correspond to an example of a communication device.
[0061]
The quasi-zenith satellite 60 with which the content reproduction device 702, the car navigation device 703, and the mobile terminal 801 communicate are, for example, three satellites orbiting the three satellite orbits shown in FIG. Of the quasi-zenith satellites of the aircraft, two quasi-zenith satellites meet in sequence at about every 8 hours at the meeting point, and the content reproduction device 702, the car navigation device 703, and the portable terminal 801 meet with the two quasi-zenith satellites When meeting at a point, the satellite to be communicated is switched (handover is performed).
This switching may be performed by the content reproduction device 702, the car navigation device 703, and the portable terminal 801 according to an instruction from the quasi-zenith satellite. When the content reproduction device 702, the car navigation device 703, and the portable terminal 801 receive signals from two of the three quasi-zenith satellites, the content reproduction device 702, the car navigation device 703, The mobile terminal 801 may automatically switch.
Each of the quasi-zenith satellites 60 orbits the satellite orbit at the orbit deviation angle shown in the first embodiment. When the satellite with which the content reproduction device 702, the car navigation device 703, and the portable terminal 801 are communicating before the handover is the first artificial satellite, and the satellite with which the communication is performed after the handover is the second artificial satellite, the first artificial satellite And the second satellite can pass through the orbit intersection without overlapping the first holding range and the second holding range. In other words, the satellite for receiving satellite 701 or the antenna of the portable terminal 801 is simultaneously used by two satellites (the first artificial satellite and the second artificial satellite) without collision of the first artificial satellite and the second artificial satellite at the meeting point. ) Will be close enough to be able to communicate with). For example, in the case where the allowable deviation angle described in the first embodiment is 0.1 degree, when the angle between the first artificial satellite and the meridian passing through the orbital intersection is 0.14 degrees, the second artificial satellite And the angle between the meridian and the meridian passing through the orbital intersection is greater than 0.14 degrees and equal to or less than 1.36 degrees.
Since the quasi-zenith satellites 60 approach each other in this manner, the content reproduction device 702, the car navigation device 703, and the portable terminal 801 each communicate with the first artificial satellite and the second artificial satellite with one antenna at the time of handover. , And delay time control at the time of handover can be easily performed.
[0062]
In the above, a mobile communication device such as a content reproduction device, a car navigation device, or a portable terminal is described as an example of a communication device on the ground. However, a fixed communication device may be used.
[0063]
In the above description, the content reproduction device, the car navigation device, and the mobile terminal receive the content information, the positioning information, and the correction information, but may receive other information.
[0064]
In the above description, the quasi-zenith satellite is described as an example. However, a satellite other than the quasi-zenith satellite may be used as long as the satellite that communicates with the terrestrial communication device is sequentially switched.
[0065]
As described above, according to the present embodiment, the communication device is configured such that the first artificial satellite and the second artificial satellite that pass through the orbital intersection approach each other so as not to overlap the first holding range and the second holding range. In this case, the first artificial satellite and the second artificial satellite can be captured by one antenna at the time of handover, and delay time control at the time of handover can be easily performed.
[0066]
【The invention's effect】
As described above, according to the present invention, the first artificial satellite and the second artificial satellite can pass through the orbital intersection without overlapping the first holding range and the second holding range. The distance between the first satellite and the second satellite at the orbital intersection can be reduced while avoiding collision at the orbital intersection. For this reason, the distance between the satellites at the time of handover from the ground can be reduced, and only one antenna for signal transmission on the ground is required, so that the control of the delay time of the transmission signal at the time of handover becomes easy.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a satellite orbit of a quasi-zenith satellite.
FIG. 2 is a diagram illustrating an example of a satellite orbit of a quasi-zenith satellite.
FIG. 3 is a diagram illustrating a configuration example of an information processing apparatus according to the first embodiment;
FIG. 4 is a diagram showing a positional relationship when a satellite in a first orbit and a satellite in a second orbit meet.
FIG. 5 is a diagram showing a positional relationship when a satellite in a first orbit and a satellite in a second orbit meet.
FIG. 6 is a diagram showing a positional relationship when a satellite in a first orbit and a satellite in a second orbit meet.
FIG. 7 is a flowchart showing a procedure for determining a raceway surface deviation angle.
FIG. 8 is a diagram showing a positional relationship when a satellite in a first orbit and a satellite in a second orbit meet.
FIG. 9 is a diagram showing a positional relationship between a satellite in a first orbit and a satellite in a second orbit, together with an ideal position of the satellite in the second orbit.
FIG. 10 is a diagram illustrating an example of a satellite orbit of a quasi-zenith satellite by adding an ideal position and an actual position of each satellite.
FIG. 11 is a diagram showing an example of a satellite orbit of a quasi-zenith satellite by adding an ideal position and an actual position of each satellite.
FIG. 12 is a diagram showing a configuration example of a trajectory control device according to the second embodiment.
FIG. 13 is a diagram showing a configuration example of an artificial satellite according to the second embodiment.
FIG. 14 illustrates an example of a communication device according to Embodiment 3.
FIG. 15 is a diagram illustrating a process of deriving an eccentricity of 0.099.
FIG. 16 is a view for explaining a process of deriving an eccentricity of 0.099.
FIG. 17 is a view for explaining a process of deriving an eccentricity of 0.099.
FIG. 18 is a view for explaining a process of deriving an eccentricity of 0.099.
[Explanation of symbols]
Reference Signs List 10 first orbit, 20 second orbit, 30 third orbit, 40 information processing device, 50 orbit control device, 60 quasi-zenith satellite, 401 input unit, 402 display unit, 403 allowable deviation angle determination unit, 404 first parallel Trajectory setting unit, 405 second parallel trajectory setting unit, 406 first holding range setting unit, 407 second holding range setting unit, 408 orbit information storage unit, 409 reference angle calculation unit, 410 orbit deviation angle determination unit , 501 satellite communication unit, 502 satellite position estimation unit, 503 orbit information storage unit, 504 control instruction unit, 701 satellite reception antenna, 702 content reproduction device, 703 car navigation device, 801 mobile terminal.

Claims (25)

An information processing apparatus for determining an orbital plane deviation angle in a second satellite orbit of a second artificial satellite orbiting a second satellite orbit intersecting an orbital intersection with a first satellite orbit where the first artificial satellite orbits And
An allowable deviation angle determination unit that determines an allowable deviation range of the orbital position deviation when the first artificial satellite and the second artificial satellite orbit the satellite orbit as an allowable deviation angle;
A first holding range setting in which a region where at least a part of the outer edge is separated from the first artificial satellite by an allowable deviation angle with respect to the first satellite is set, and the region is set as a first holding range. Department and
A second holding range setting in which a region where at least a part of the outer edge is located at a position separated by an allowable deviation angle from the second satellite with respect to the second satellite is set as the second holding range Department and
The orbital plane deviation angle at which the first satellite and the second satellite can pass through the orbital intersection without overlapping the first holding range and the second holding range with the orbit of the second satellite An information processing apparatus comprising: a track surface deviation angle determination unit that determines a surface deviation angle. The information processing device further includes:
A first parallel trajectory setting unit that sets two parallel trajectories parallel to the first satellite orbit at positions separated by an allowable deviation angle from the first satellite orbit, and sets the parallel trajectory as a first parallel trajectory;
A second parallel trajectory setting unit that sets two parallel trajectories parallel to the second satellite orbit at positions separated by an allowable deviation angle from the second satellite orbit and sets the parallel trajectory as a second parallel trajectory; Have
The first holding range setting unit includes:
As a first holding range, a rectangle whose two sides are on a first parallel locus around the first artificial satellite is set,
The second holding range setting unit includes:
The information processing apparatus according to claim 1, wherein a rectangle having two sides on a second parallel locus centering on the second artificial satellite is set as the second holding range. The information processing device further includes:
In the rectangle of the holding range of the first artificial satellite, one of the vertices located forward or backward in the traveling direction of the first artificial satellite is such that one of the vertices is inside the second parallel locus and the other is the first vertex. A reference angle calculation unit that calculates, as a reference angle, an angle between the first artificial satellite and a meridian passing through the orbital intersection when the intersection of the parallel trajectory and the second parallel trajectory overlaps,
The raceway surface deviation angle determining unit includes:
Orbital plane where the angle between the second satellite and the meridian passing through the orbital intersection when the angle between the first satellite and the meridian passing through the orbital intersection is the reference angle is greater than the reference angle The information processing apparatus according to claim 2, wherein the deviation angle is determined as an orbital plane deviation angle of the second artificial satellite. The information processing device,
The ascending ascensions differed by almost 120 degrees, the orbit inclination was equal to 45 degrees, the perigee argument was equal to 270 degrees, the orbital cycle was almost equal to the geostationary satellite orbital cycle, and a common eccentricity of 0.099 was set. 4. The satellite according to claim 1, wherein any two of the three satellites orbiting the three satellite orbits are a first satellite and a second satellite, respectively. An information processing apparatus according to claim 1. The information processing device,
The ascending ascensions differed by almost 120 degrees, the orbit inclination was equal to 45 degrees, the perigee argument was equal to 270 degrees, the orbital cycle was almost equal to the geostationary satellite orbital cycle, and a common eccentricity of 0.099 was set. Any two of the three satellites orbiting each of the three satellite orbits are defined as a first satellite and a second satellite,
The allowable deviation angle determination unit,
Determine the allowable deviation angle as 0.1 degree,
The reference angle calculation unit,
The reference angle is calculated as 0.14 degrees based on the allowable deviation angle of 0.1 degrees,
The raceway surface deviation angle determining unit includes:
The angle between the second satellite and the meridian passing through the orbital intersection is greater than 0.14 degrees when the angle between the first satellite and the meridian passing through the orbital intersection is 0.14 degrees. The information processing apparatus according to claim 3, wherein the orbital plane deviation angle that is equal to or less than 1.36 degrees is determined as the orbital plane deviation angle of the second artificial satellite. An orbit control device that performs an orbit control for a second artificial satellite orbiting a second satellite orbit intersecting an orbital intersection with a first satellite orbit that the first artificial satellite orbits,
An allowable deviation range of the orbital position deviation when the first artificial satellite and the second artificial satellite orbit the satellite orbit is defined as an allowable deviation angle,
A first holding range is a region in which at least a part of the outer edge is located at a position separated by an allowable deviation angle from the first satellite with respect to the first satellite,
A second holding range is a region in which at least a part of the outer edge of the second satellite is located at a position separated by an allowable deviation angle from the second satellite,
The second artificial satellite has an orbital plane deviation angle at which the first artificial satellite and the second artificial satellite can pass through the orbital intersection without overlapping the first holding range and the second holding range. An orbit control device for performing orbit control on a second artificial satellite so as to orbit a second satellite orbit. The trajectory control device,
Two parallel trajectories parallel to the first satellite orbit set at positions separated by an allowable deviation angle from the first satellite orbit are defined as a first parallel trajectory,
Two parallel trajectories parallel to the second satellite orbit set at positions separated by an allowable deviation angle from the second satellite orbit are defined as a second parallel trajectory,
A rectangle having two sides on a first parallel locus around the first artificial satellite is defined as a first holding range,
The orbit control device according to claim 6, wherein a rectangle whose two sides are on a second parallel locus around the second artificial satellite is set as a second holding range. The trajectory control device,
In the rectangle of the holding range of the first artificial satellite, one of the vertices located forward or backward in the traveling direction of the first artificial satellite is such that one of the vertices is inside the second parallel locus and the other is the first vertex. The angle between the first artificial satellite and the meridian passing through the orbital intersection when overlapping with the intersection of the parallel trajectory and the second parallel trajectory is defined as a reference angle,
Orbital plane where the angle between the second satellite and the meridian passing through the orbital intersection when the angle between the first satellite and the meridian passing through the orbital intersection is the reference angle is greater than the reference angle The orbit control device according to claim 7, wherein the orbit control for the second artificial satellite is performed such that the second artificial satellite orbits the second satellite orbit at the deviation angle. The trajectory control device,
The ascending ascensions differed by almost 120 degrees, the orbit inclination was equal to 45 degrees, the perigee argument was equal to 270 degrees, the orbital cycle was almost equal to the geostationary satellite orbital cycle, and a common eccentricity of 0.099 was set. 9. The satellite according to claim 6, wherein any one of the three satellites orbiting each of the three satellite orbits is a first satellite and a second satellite. The trajectory control device according to 1. The trajectory control device,
The ascending ascensions differed by almost 120 degrees, the orbit inclination was equal to 45 degrees, the perigee argument was equal to 270 degrees, the orbital cycle was almost equal to the geostationary satellite orbital cycle, and a common eccentricity of 0.099 was set. Any two of the three satellites orbiting each of the three satellite orbits are defined as a first satellite and a second satellite,
When the allowable deviation angle is 0.1 degree and the reference angle is 0.14 degree,
The angle between the second satellite and the meridian passing through the orbital intersection is greater than 0.14 degrees when the angle between the first satellite and the meridian passing through the orbital intersection is 0.14 degrees. The orbit control for the second artificial satellite is performed so that the second artificial satellite orbits the second satellite orbit at an orbital plane deviation angle of 1.36 degrees or less. Item 9. An orbit control device according to item 8. An artificial satellite orbiting a satellite orbit that intersects a satellite orbit of another artificial satellite that orbits another artificial satellite at an orbital intersection,
The allowable deviation range of the orbital position deviation when the other artificial satellite and the own artificial satellite orbits the satellite orbit is defined as an allowable deviation angle, and at least a part of the outer edge of the other artificial satellite is an allowable deviation angle from the other artificial satellite. The area at the separated position is the holding range of other satellites, and the area at the center of the own satellite and at least a part of the outer edge is separated from the own satellite by an allowable deviation angle is the holding range of the own satellite. And if
The satellite orbit of the self-satellite at an orbital plane deflection angle that allows the other satellite and the self-satellite to pass through the orbital intersection without overlapping the holding range of the other satellite and the self-satellite An artificial satellite characterized by orbiting a satellite. The satellite is
Two parallel trajectories parallel to the satellite orbit of another satellite set at a position separated by an allowable deviation angle from the satellite orbit of the other satellite are regarded as parallel trajectories of the other satellite, and Two parallel trajectories parallel to the satellite orbit of the self-satellite set at positions separated by the allowable deviation angle are defined as parallel trajectories of the self-satellite, and two sides of the other satellite are parallel trajectories of the other satellite. When the rectangle above is the holding range of another artificial satellite, and the rectangle whose two sides are on the parallel trajectory of the own satellite with the own satellite as the center is the holding range of the own satellite,
The satellite orbit of the self-satellite at an orbital plane deflection angle that allows the other satellite and the self-satellite to pass through the orbital intersection without overlapping the holding range of the other satellite and the self-satellite The satellite according to claim 11, which orbits the satellite. The satellite is
In the rectangle of the holding range of the other satellite, one of the vertices located in front of or behind the traveling direction of the other satellite is one of the vertices inside the parallel trajectory of the own satellite and the other is the other vertex. When the angle between the other satellite and the meridian passing through the orbital intersection when overlapping with the intersection of the parallel trajectory of the satellite and the parallel trajectory of the own satellite is the reference angle,
When the angle between the satellite and the meridian passing through the orbital intersection becomes the reference angle, the angle between the own satellite and the meridian passing through the orbital intersection becomes an angle larger than the reference angle. 13. The artificial satellite according to claim 12, wherein the satellite orbits the own artificial satellite. The satellite is
The ascending ascensions differed by almost 120 degrees, the orbit inclination was equal to 45 degrees, the perigee argument was equal to 270 degrees, the orbital cycle was almost equal to the geostationary satellite orbital cycle, and a common eccentricity of 0.099 was set. One of the three artificial satellites orbiting each of the three satellite orbits, and the other artificial satellite is any one of the other two artificial satellites. The artificial satellite according to any one of claims 11 to 13. The satellite is
The ascending ascensions differed by almost 120 degrees, the orbit inclination was equal to 45 degrees, the perigee argument was equal to 270 degrees, the orbital cycle was almost equal to the geostationary satellite orbital cycle, and a common eccentricity of 0.099 was set. One of the three artificial satellites orbiting each of the three satellite orbits, and the other artificial satellite being one of the other two artificial satellites;
When the allowable deviation angle is 0.1 degree and the reference angle is 0.14 degree,
When the angle between the satellite and the meridian passing through the orbital intersection is 0.14 degrees when the angle between the other satellite and the meridian passing through the orbital intersection is greater than 0.14 degrees, The satellite according to claim 13, wherein the satellite orbits the satellite at an orbital plane deviation angle of 1.36 degrees or less. A first satellite orbiting in a first satellite orbit and a second satellite orbiting in a second satellite orbit intersecting the first satellite orbit at an orbital intersection and communicating with a predetermined satellite switching time A communication device for switching an artificial satellite to be communicated from a first artificial satellite to a second artificial satellite,
The allowable deviation range of the orbital position deviation when the first artificial satellite and the second artificial satellite orbit the satellite orbit is defined as an allowable deviation angle, and at least a part of the outer periphery of the first artificial satellite is the first artificial satellite. An area located at a position separated by an allowable deviation angle from the satellite is defined as a first holding range, and an area where at least a part of the outer edge is located at a position separated by an allowable deviation angle from the second artificial satellite around the second artificial satellite. Is the second holding range,
The second satellite orbit at an orbital plane deviation angle at which the first satellite and the second satellite can pass through the orbital intersection without overlapping the first holding range and the second holding range. A communication device for switching to a second artificial satellite that orbits. The communication device,
Two parallel trajectories parallel to the first satellite orbit set at positions separated by an allowable deviation angle from the first satellite orbit are defined as first parallel trajectories, and positions separated by an allowable deviation angle from the second satellite orbit. , Two parallel trajectories parallel to the second satellite orbit set as the second parallel trajectory, and a rectangle having two sides on the first parallel trajectory around the first artificial satellite is defined as a first holding range. When a rectangle whose two sides are on a second parallel locus around the second artificial satellite is set as a second holding range,
The second satellite orbit at an orbital plane deviation angle at which the first satellite and the second satellite can pass through the orbital intersection without overlapping the first holding range and the second holding range. The communication device according to claim 16, wherein the communication device is switched to a second artificial satellite that orbits. The communication device,
In the rectangle of the first holding range, one vertex of two vertices located forward or rearward in the traveling direction of the first artificial satellite is inside the second parallel locus, and the other vertex is the first parallel locus. When the angle between the first artificial satellite and the meridian passing through the orbital intersection at the time of overlapping with the intersection with the second parallel trajectory is defined as the reference angle,
Orbital plane where the angle between the second satellite and the meridian passing through the orbital intersection when the angle between the first satellite and the meridian passing through the orbital intersection is the reference angle is greater than the reference angle 18. The communication device according to claim 17, wherein the communication device is switched to a second artificial satellite that orbits a second satellite orbit at a bias angle. The communication device,
The ascending ascensions differed by almost 120 degrees, the orbit inclination was equal to 45 degrees, the perigee argument was equal to 270 degrees, the orbital period was approximately equal to the geostationary satellite orbital period, and a common eccentricity of 0.099 was set. 19. A satellite according to claim 16, wherein any one of the three satellites orbiting each of the three satellite orbits is a first satellite and a second satellite. The communication device according to claim 1. The communication device,
The ascending ascensions differed by almost 120 degrees, the orbit inclination was equal to 45 degrees, the perigee argument was equal to 270 degrees, the orbital period was approximately equal to the geostationary satellite orbital period, and a common eccentricity of 0.099 was set. Any two of the three satellites orbiting each of the three satellite orbits are defined as a first satellite and a second satellite,
When the allowable deviation angle is 0.1 degree and the reference angle is 0.14 degree,
When the angle between the satellite and the meridian passing through the orbital intersection is 0.14 degrees when the angle between the other satellite and the meridian passing through the orbital intersection is greater than 0.14 degrees, 19. The communication device according to claim 18, wherein the communication device is switched to a second artificial satellite that orbits the second satellite orbit at an orbital plane deviation angle of 1.36 degrees or less. Communication with a first artificial satellite orbiting a first satellite orbit and a second artificial satellite orbiting a second satellite orbit intersecting the first satellite orbit at an orbital intersection, and a predetermined satellite switching time A communication method for switching an artificial satellite to be communicated from a first artificial satellite to a second artificial satellite,
The allowable deviation range of the orbital position deviation when the first artificial satellite and the second artificial satellite orbit the satellite orbit is defined as an allowable deviation angle, and at least a part of the outer periphery of the first artificial satellite is the first artificial satellite. An area located at a position separated by an allowable deviation angle from the satellite is defined as a first holding range, and an area where at least a part of the outer edge is located at a position separated by an allowable deviation angle from the second artificial satellite around the second artificial satellite. Is the second holding range,
The second satellite orbit at an orbital plane deviation angle at which the first satellite and the second satellite can pass through the orbital intersection without overlapping the first holding range and the second holding range. A communication method comprising switching to a second orbiting satellite. The communication method includes:
Two parallel trajectories parallel to the first satellite orbit set at positions separated by an allowable deviation angle from the first satellite orbit are defined as first parallel trajectories, and positions separated by an allowable deviation angle from the second satellite orbit. , Two parallel trajectories parallel to the second satellite orbit set as the second parallel trajectory, and a rectangle having two sides on the first parallel trajectory around the first artificial satellite is defined as a first holding range. When a rectangle whose two sides are on a second parallel locus around the second artificial satellite is set as a second holding range,
The second satellite orbit at an orbital plane deviation angle at which the first satellite and the second satellite can pass through the orbital intersection without overlapping the first holding range and the second holding range. 22. The communication method according to claim 21, wherein the communication method is switched to a second artificial satellite that orbits. The communication method includes:
In the rectangle of the first holding range, one vertex of two vertices located forward or rearward in the traveling direction of the first artificial satellite is inside the second parallel locus, and the other vertex is the first parallel locus. When the angle between the first artificial satellite and the meridian passing through the orbital intersection at the time of overlapping with the intersection with the second parallel trajectory is defined as the reference angle,
Orbital plane where the angle between the second satellite and the meridian passing through the orbital intersection when the angle between the first satellite and the meridian passing through the orbital intersection is the reference angle is greater than the reference angle 23. The communication method according to claim 22, wherein switching is performed to a second artificial satellite that orbits the second satellite orbit at a bias angle. The communication method includes:
The ascending ascensions differed by almost 120 degrees, the orbit inclination was equal to 45 degrees, the perigee argument was equal to 270 degrees, the orbital period was approximately equal to the geostationary satellite orbital period, and a common eccentricity of 0.099 was set. 24. Any one of the three artificial satellites orbiting the three satellite orbits, respectively, wherein two artificial satellites are a first artificial satellite and a second artificial satellite. Communication method described in. The communication method includes:
The ascending ascensions differed by almost 120 degrees, the orbit inclination was equal to 45 degrees, the perigee argument was equal to 270 degrees, the orbital period was approximately equal to the geostationary satellite orbital period, and a common eccentricity of 0.099 was set. Any two of the three satellites orbiting each of the three satellite orbits are defined as a first satellite and a second satellite,
When the allowable deviation angle is 0.1 degree and the reference angle is 0.14 degree,
When the angle between the other satellite and the meridian passing through the orbit intersection is 0.14 degrees, the angle between the own satellite and the orbit intersection is greater than 0.14 degrees and 1.36. 24. The communication method according to claim 23, wherein the switching to the second artificial satellite orbiting the second satellite orbit is performed at an orbit deviation angle that is equal to or less than a degree.

Images