JP3656604B2 - Link travel time estimation apparatus and method - Google Patents

Description

【００２２】
―道路網―
図３は、路上ビーコン、カメラ等が設置された道路網のエリア地図である。
この地図では、道路は、縦横複数本描かれ、交差点が存在する。交差点間の道路を１リンク単位としてとらえ、上り下りのリンクＬ１〜ＬＮ（図３ではＮ＝４８）を構成している。リンク同士の十字接続点が交差点ノードＮ１，Ｎ２，‥‥，Ｎ９となっている。
【００２３】
路上ビーコンは、各リンクから交差点に進入する位置に設置され、黒い▲印で表されている。カメラは、一定範囲の道路を見下ろす形で随所に設置されている。なお、路上ビーコンは、図３では、各交差点に設置されたように描かれているが、実際には、設置されていない交差点も存在する。また、交差点に進入する位置以外にも設置されることがある。
また、道路の途中から細街路がつながり、道路の途中に店舗や住宅の駐車場が存在している。この図３では、作図の都合上、一部の道路のみに細街路や駐車場を描いているが、実際には、ほとんどの道路に細街路がつながり、駐車場が存在している。
【００２４】
―センター装置―
図４は、センター装置Ａ内の機能ブロック図である。センター装置Ａは、路上ビーコンＢとの間の送受信信号を変換する入力変換部１、カメラの画像信号を変換する入力変換部２、路上ビーコンＢの車両感知信号に基づいて、地点交通量（地点を通過する単位時間当たりの車両台数）を算出する交通量計測部３、路上ビーコンＢの送受信信号やカメラの画像信号に基づいて、車両の識別コード、通過時刻、車種、前回通過した路上ビーコンのコード、前回路上ビーコンを通過した時点からの走行時間のデータを取得しメモリに蓄積するデータ集計部４、データ集計部４のメモリに蓄積されたデータを取り出して、そのデータに基づいてＯＤ間走行経路を求めるＯＤ走行経路演算部５、ＯＤ間走行経路を統計的に処理することによりＯＤ交通量（Ｑ1）を算出するとともに、交通量計測部３により算出された地点交通量に基づいてＯＤ交通量（Ｑ2）を算出し、両ＯＤ交通量（Ｑ1，Ｑ2）に基づいて、最終的なＯＤ交通量（Ｑ）を推定するＯＤ交通量推定部６、ＯＤ間走行経路に基づいてリンク旅行時間を推定するリンク旅行時間推定部７を備えている。図４の円筒形は、それぞれの部位に所属するメモリを示している。
【００２５】
センター装置Ａは、コンピュータ、メモリ、入出力装置等を備え、前記交通量計測部３、データ集計部４、ＯＤ走行経路演算部５、ＯＤ交通量推定部６、リンク旅行時間推定部７で行う各処理機能の全部又は一部は、前記メモリに記録されたプログラムをコンピュータが実行することにより実現される。
以下、交通量計測部３、ＯＤ走行経路演算部５、ＯＤ交通量推定部６、リンク旅行時間推定部７で行う各処理を、必要ならばフローチャートを用いて順に説明する。
【００２６】
−交通量計測−
交通量計測部３は、入力変換部１から得られる、路上ビーコンＢの感知信号に基づいて地点交通量（単位時間（例えば５分間）あたりの車両の通過台数）を算出する。路上ビーコンＢはリンクごとに設置されているので、地点交通量もリンクごとに求められる。したがって、以下「リンク地点交通量」という。
さらに交通量計測部３は、占有時間Ｏ（単位時間（例えば５分間）内に、各車両ｋが車両感知器を横切った時間ｔkの総和Σｔk）を検知する。
【００２７】
また、交通量計測部３は、次のようにしてリンク旅行時間を計測する。
地点交通量計測値ｑ、占有時間Ｏ、及び平均車長（一定値とする）Ｉを用いて、式Ｖ＝Ｉ・ｑ／Ｏにより車両の平均速度Ｖを計算し、これとリンクの長さＬを用いて、式Ｔ＝Ｌ／Ｖによりリンク旅行時間Ｔを計算する。
また、カメラの計測画像から車両のプレートナンバーをマッチングして車両を同定し、同一車両がリンクの端を通過した時刻とリンクの他の端を通過した時刻とから、リンクを走行するのに要した時間Ｔ′を求める。単位時間に通過した車両が複数であれば、各車両のリンク旅行時間Ｔ′の平均をとる。
【００２８】
そして、以上のようにして求めたリンク旅行時間Ｔ若しくはリンク旅行時間Ｔ′のいずれか、またはこれらの重み付き平均をとって、リンク旅行時間とする。なお、旅行時間の計測誤差を吸収するためにフィルター値を用いてもよい。また曜日、時間帯、天候等によってばらつきがあるので、過去の統計的な値を加味してもよい。
−ＯＤ走行経路演算−
図５、ＯＤ走行経路演算部５の行うＯＤ走行経路演算処理を説明するためのフローチャートである。
【００２９】
まず、データ集計部４のメモリに蓄積された所定日数分の車両の識別コード、通過時刻、車種、前回通過した路上ビーコンのコード、前回路上ビーコンを通過した時点からの走行時間のデータ（表１）を取得する（ステップＶ１）。そして、このデータを識別コードごとにソートして、メモリに記憶する（ステップＶ２）。この情報を「基本情報」という。
表２は、基本情報の一覧表である。表２によれば、例えば識別コード“１” ，“２”，・・， “１２３”の車両の情報が、それぞれひとかたまりにまとめられている。
【００３０】
【表２】

【００３１】
基本情報から同一車両の識別コードのデータを取り出す（ステップＶ３）。この同一車両の識別コードのデータに基づいて、通過した路上ビーコンを通過時刻順に並べ替える（ステップＶ５）。これにより、通過した路上ビーコンを通過順に特定できる。また、最も早く通過し「前回通過したビーコンなし」のフラグが付されている路上ビーコンが車両の発生地点（Ｏ）を表し、最新の時点に通過した路上ビーコンが車両の消滅地点（Ｄ）を表す。
【００３２】
次に、通過路上ビーコン間の走行経路を求める（ステップＶ７）。路上ビーコンＢは、通常、図３に示すように、交差点ごとに設置されているので、通過路上ビーコン間の走行経路とは、交差点間を結ぶ道路となる。しかし、路上ビーコンＢが交差点ごとに設置されていない場合、あるいは車両が路上ビーコンＢの設置されていない道路を通過した場合は、走行経路が一意的に定まらないので、公知のダイクストラ法、ポテンシャル法等に基づいて通過路上ビーコン間の、リンク距離に基づく最短距離経路(Ａ)を算出する（例えば特開平７−２４４７９８号公報参照）。
【００３３】
データの中に、「前回通過した路上ビーコンなし」との情報が入っていれば、ここを車両発生地点（Ｏ）とみなして、当該識別コードの車両の走行経路の調査をこれで打ち切る（ステップＶ６のＮＯ）。この場合は、ステップＶ３に戻り、他の識別コード（すなわち他の車両）の基本情報についての調査を開始する。
以上のようにして、各車両のＯＤ間の最短距離経路情報が求まるので、所定のメモリに記憶する（ステップＶ８）。
【００３４】
−リンク旅行時間推定−
図６は、リンク旅行時間推定部７で行うリンク旅行時間推定処理を説明するためのフローチャートである。
まず、ＯＤ間の最短距離経路(Ａ)がリンク旅行時間の情報が提供されていないリンク（以下「交通情報非提供リンク」という）を含むかどうか調べる（ステップＶ９）。交通情報非提供リンクを含む場合は、リンク旅行時間の情報が提供されているリンク（以下「交通情報提供リンク」という）のみを対象にして、参考経路となるＯＤ間最短時間経路（Ｂ）を算出する（ステップＶ１０）。
【００３５】
交通情報非提供リンクを含まない場合、すなわちＯＤ間の最短距離経路(Ａ)が交通情報提供リンクのみからなる場合も、ＯＤ間最短時間経路（Ｂ）を算出する（ステップＶ１０）。これは、交通情報提供リンクの旅行時間がすでに求まっているものの、本発明のリンク旅行時間推定処理によって、その旅行時間情報をアップデートしたいというニーズを考慮したものである。しかし、交通情報提供リンクの旅行時間が別の方法により求まっているので、あえて本発明のリンク旅行時間推定処理を行わない、という選択も可能である。その意味で、図６に注）を記した。
【００３６】
次に、ステップＶ１１に進み、ＯＤ間の最短距離経路(Ａ)で計測したＯＤ地点間の旅行時間ＴAと、ＯＤ間の最短時間経路(Ｂ)で計測したＯＤ地点間の旅行時間ＴBとを比較する。
これらの旅行時間ＴA，ＴBが一定の基準（後述）を満たしているかどうかを判定し（ステップＶ１２）、一定の基準を満たしていれば、車両がＯＤ間の最短距離経路(Ａ)を走行した可能性が高いと見て、ＯＤ間の最短距離経路(Ａ)を構成するリンクのリンク旅行時間を推定し、その値を記憶する（ステップＶ１３）。一定の基準を満たしていなければ、車両がＯＤ間の最短距離経路(Ａ)を走行した可能性が低いので、ＯＤ間の最短距離経路(Ａ)を構成するリンクのリンク旅行時間推定処理を行わない。
【００３７】
そして、他の車両についても、同じようにリンク旅行時間を推定し、リンク旅行時間のデータを蓄積していく。蓄積されたリンク旅行時間のデータを統計処理（例えば平均化）すれば、より精度のよいリンク旅行時間が求まる。このリンク旅行時間を、経路計算のための基礎データとして活用することができる（ステップＶ１４）。
以下、このリンク旅行時間推定処理を、具体例を用いながらさらに詳しく説明する。
【００３８】
最短距離経路(Ａ)の算出： 図７は、最短距離経路(Ａ)の算出方法を説明するための道路地図である。ビーコン４２，２７，２０は、表２の、車両識別コード１２３の車両の通過したビーコン番号を表している。また、図７の太い道路は、交通情報提供リンクに対応する道路を、細い道路は、交通情報非提供リンクに対応す細街路を表している。これらのビーコン４２，２７，２０を順に通過した最短距離経路(Ａ)を算出すれば、図７の破線で示した経路となる。この経路は、細街路すなわち交通情報非提供リンクＬa，Ｌbを含む経路となっている。なお、最短距離経路(Ａ)を算出する基準として、リンク距離に加えて、右左折回数制限、右左折コスト、高速道路・幹線道路走行指定の有無、当該車種が対象となる交通規制、道路幅などの基準を適宜加えてもよい。
【００３９】
最短時間経路（Ｂ）の算出： 図８は、最短時間経路（Ｂ）の算出方法を説明するための道路地図である。ビーコンは、車両発生地点のビーコン４２と、車両消滅地点のビーコン２０のみを図示している。最短時間経路（Ｂ）の算出にあたっては、交通情報提供リンク、すなわち図８の太い道路のみしか対象にできない。リンクコストとしては、すでに交通量計測等によって求まっているリンク旅行時間を用いる。この最短時間経路（Ｂ）を、図８に破線で示す。なお、最短時間経路(Ｂ)を算出する基準として、リンク旅行時間に加えて、右左折回数制限、右左折コスト、高速道路・幹線道路走行指定の有無、当該車種が対象となる交通規制、道路幅などの基準を適宜加えてもよい。
【００４０】
最短距離経路(Ａ)で計測した旅行時間ＴA： この旅行時間ＴAは、車両のビーコン４２の通過時刻とビーコン２０の通過時刻との差から求める。具体的には、表２を参照して、車両１２３がビーコン４２を通過した時刻は、８時２０分２５秒であり、ビーコン２０を通過した時刻は、８時５０分５８秒である。この差１８３３秒が旅行時間ＴAである。
最短時間経路(Ｂ)で算出した旅行時間ＴB： この旅行時間ＴBは、最短時間経路（Ｂ）を求めるために用いたリンク旅行時間の合計となる。
【００４１】
旅行時間ＴAと旅行時間ＴBとの比較： 最短距離経路(Ａ)の距離ＬAと最短時間経路（Ｂ）の距離ＬBとの距離比ＬA／ＬBを求め、旅行時間ＴBにこの距離比をかけて、最短距離経路(Ａ)の旅行時間に換算する。この換算された旅行時間と、旅行時間ＴAとの比をとり、この比が１を含む一定の範囲に入っているかどうかを判断する。１を含む一定の範囲に入っていれば、ステップＶ１２の一定の基準を満たしているとする。なお、前記一定の範囲は、実際にシステムを運用した上で経験的に求められる範囲である。例えば０．５から２．０までの範囲を例示できる。
【００４２】
最短距離経路(Ａ)を構成するリンクのリンク旅行時間の推定： 通過したビーコン間の旅行時間を、リンク距離比で配分して、リンク旅行時間を推定する。
次の２つの方法１，２が考えられる。
方法１ リンク旅行時間を求めようとするリンクの距離を、通過したビーコン間の距離で割って、それにビーコン間の通過時間をかけて、リンク旅行時間を推定する。例えば図７を参照して、リンク旅行時間を求めようとするリンクＬaの距離を、通過したビーコン４２，２７間の距離で割って、それにビーコン４２，２７間の通過時間（８時４１分２５秒−８時２０分２５秒）をかけて、リンクＬaのリンク旅行時間を推定する。
【００４３】
方法２ 交通情報提供リンクに係る旅行時間を、交通量計測等によって求まっている既知のリンク旅行時間を用いて求める。そして、通過したビーコン間の旅行時間から、交通情報提供リンクに係る旅行時間を引くことにより、交通情報非提供リンクのリンク旅行時間を推定する。例えば、図７を参照して、発生地点ＯからＸまでの旅行時間を、Ｙから消滅地点Ｄまでの旅行時間を既知のリンク旅行時間を用いて求め、ビーコン４２，２７間の通過時間からこの交通情報提供リンクに係る旅行時間を引くことにより、リンクＬa及びリンクＬbのリンク旅行時間を推定する。リンクＬaのリンク旅行時間、リンクＬbのリンク旅行時間は、それぞれ距離比で配分して求める。
【００４４】
以上で、本発明の実施の形態を説明したが、本発明の実施は、前記の形態に限定されるものではない。例えば、車載装置にＧＰＳ(Global Positioning System)などの車両位置検出機能を持たせ、車載装置から、識別コードと車両検出位置の情報を地上装置に取り込み、地上装置において、前述したセンター装置Ａと同様の構成を備えることにより、各車両のＯＤ間走行経路を求め、このＯＤ間走行経路に基づいて、リンク旅行時間を推定することも可能である。この場合、車載装置と地上装置との通信は、携帯電話、自動車電話、あるいは専用回線を用いて定期的にもしくは不定期に行うこととすればよい。
【００４５】
また今までの説明では、図６のリンク旅行時間推定処理において、交通量の多少に拘らず、ＯＤ間の最短距離経路(Ａ)が交通情報非提供リンクを含む場合、その交通情報非提供リンクについてリンク旅行時間を求めていた。
しかし、交通量が少なければ、得られるリンク旅行時間のデータも少ないので、統計処理しても、精度のよいリンク旅行時間が求まらない。精度の悪いリンク旅行時間のデータを使って最短時間経路計算をしても、正しい経路が求まらない。またセンター装置Ａの処理量も有限である。
【００４６】
そこで、交通量の多い交通情報非提供リンクについてのみ、リンク旅行時間推定処理を行うことが望ましい。
以下、センター装置Ａの行う、交通量の多いリンクの判定方法を説明する。
図９は、道路網地図であり、交通情報提供リンクを実線で描き、交通情報非提供リンクを破線で描いている。交通情報提供リンクの各交差点には、ビーコンＢａ〜Ｂｆが設置されているとする。車両の発生地点（Ｏ）、車両の消滅地点（Ｄ）を点で表している。
【００４７】
車両が交通情報提供リンクを走行する限り、発生地点Ｏから出発して消滅地点Ｄに至るまで、各ビーコンを順に通過していくことになる。
図１０、図１１は、交通量の多いリンクの判定方法を説明するためのフローチャートである。まず、基本情報から同一車両番号のデータを取り出し（ステップＷ１）、その車両が通過したビーコンを続けて２つずつ取り出す（ステップＷ３）。
【００４８】
前記道路網地図（図９）を参照して（ステップＷ６）、通過した交通情報提供リンクが途切れているかどうか判断する（ステップＷ７）。この判断方法を、図９を参照して説明する。
（ａ）続いて通過したビーコンが、例えばＢａからＢｂであるとき、ＢａとＢｂとの間は交通情報提供リンクで結ばれ、かつＢａとＢｂとの間の交通情報提供リンクでつないだ経路に他のビーコンは存在しない。この場合、当該車両は、交通情報提供リンクを走行したと判断する。
【００４９】
（ｂ）続いて通過したビーコンが、例えばＢａからＢｅであれば、その間をどのような交通情報提供リンクでつないだ経路を求めても、他のビーコンＢｂ，Ｂｄを経由している。このときは、ＢａとＢｅとの間の交通情報提供リンクは、途切れていると判断する。つまり、２つのビーコン間をどのような交通情報提供リンクでつないでも、その間に他のビーコンが存在するにも拘らず、車両はその間に通過すべきはずのビーコンを通過していない場合、当該車両は、交通情報非提供リンクを走行したと判断する。
【００５０】
交通情報非提供リンクを走行したと判断された場合は、ステップＷ８に進み、２つのビーコン間の最短距離経路を算出する。この最短距離経路計算の範囲は、交通情報提供リンクのみならず、交通情報非提供リンクも含むのはもちろんである。そして、算出された最短距離経路に交通情報提供リンクが含まれていないかどうか確認して（ステップＷ９）、含まれていない場合は、当該車両は、当該最短距離経路を走行した可能性が高いと考えられるので、当該最短距離経路を構成するリンクに、１を加算する。最短距離経路を構成するリンクが複数直列につながっていればそれぞれに１を加算する。（ステップＷ１０）。
【００５１】
なお、ステップＷ９で算出された最短距離経路に交通情報提供リンクが含まれていれば、車両は当該ビーコンを途中で通過した可能性が高いと考えられるが、実際には通過していないので、算出した最短距離経路を走行した可能性は低いと考える。
このような処理を、当該車両のＯＤ間で行い、当該車両について処理が済めば、他の車両についても処理を行う。
【００５２】
基本情報中のすべての車両について、前記処理が終われば、単位時間あたりの通過台数が一定以上の交通情報非提供リンクのみをマークする。この判定しきい値は、経験上定める。
このマークされた交通情報非提供リンクについてのみ、前述したリンク旅行時間推定処理を行う。
【００５３】
【発明の効果】
以上のように本発明によれば、車両の通過位置を最短経路で結ぶことにより、この最短経路を構成するリンクのリンク旅行時間を精度よく推定することができる。したがって、この推定されたリンク旅行時間を用いて最短時間経路計算に役立てることができる。
【図面の簡単な説明】
【図１】路上ビーコンＢの配置図である。
【図２】路上ビーコンＢからセンター装置にデータを送信する手順を説明するフローチャートである。
【図３】路上ビーコンＢ、カメラ等が設置された道路網のエリア地図である。
【図４】センター装置の機能ブロック図である。
【図５】ＯＤ走行経路演算部５の行うＯＤ走行経路演算処理を説明するためのフローチャートである。
【図６】リンク旅行時間推定部７で行うリンク旅行時間推定処理を説明するためのフローチャートである（図５の続き）。
【図７】最短距離経路(Ａ)の算出方法を説明するための道路地図である。
【図８】最短時間経路（Ｂ）の算出方法を説明するための道路地図である。
【図９】交通情報提供リンク、交通情報非提供リンク、ビーコンを含む道路網地図である。
【図１０】交通量の多いリンクの判定方法を説明するためのフローチャートである。
【図１１】交通量の多いリンクの判定方法を説明するためのフローチャート（図１０の続き）である。
【符号の説明】
１ 入力変換部
２ 入力変換部
３ 交通量計測部
４ データ集計部
５ ＯＤ走行経路演算部
６ ＯＤ交通量推定部
７ リンク旅行時間推定部
Ａ センター装置
Ｂ 路上ビーコン
Ｂ１ 投受光器
Ｂ２ 制御装置
Ｃ 車載装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a link for estimating link travel time based on communication between an in-vehicle device (including both a device installed in a vehicle and a device brought into the vehicle) that transmits an identification code and a ground device. The present invention relates to a travel time estimation apparatus and method.
[0002]
[Prior art]
In a road network of a certain scale, a travel route that is traced from when a vehicle is generated until it disappears is called an inter-OD travel route.
The “occurrence” means a case where a vehicle enters the road network of a certain scale from a road network (narrow street) or a parking lot of a smaller scale, and the “disappearance” means a road of the certain scale. This refers to the case where a vehicle exits from the net to the narrow street or parking lot.
[0003]
When the travel route between ODs for each vehicle is obtained, this can be statistically processed to obtain the OD traffic volume. OD traffic volume is also referred to as origin / endpoint traffic volume, and refers to the number of vehicles per unit time that originates from a certain point on a road network and disappears at other points (Ryuichi Mato et al. "Matsushita Technical Journal Vol. 44 No. 3 Jun. 1998).
Also, a trip that occurs from one point, passes through a certain route, and disappears at another point is called “trip”. The travel route between ODs is nothing but the trip route.
[0004]
[Problems to be solved by the invention]
A technique for calculating the shortest time path along which a vehicle travels between two points is widely known. To calculate the shortest time route, it is necessary to know the travel time of the road section (link), but at present, the link travel time of major roads is measured and statistics are obtained, but for all links Travel time is not measured.
On the other hand, the inter-OD travel route is a route obtained as a result of each vehicle communicating between the in-vehicle device and the ground device, and includes information on the point passage time.
[0005]
Therefore, it is considered that the link travel time can be obtained by using the information on the inter-OD travel route on the road where the link travel time information is not provided.
However, the ground equipment is not capable of precisely grasping the movement of the position of a large number of vehicles throughout the country. Currently, when a vehicle passes the beacon by a road beacon installed at a major intersection of the road It is only possible to grasp the position of the vehicle.
[0006]
Thus, there is a need to realize a link travel time estimation device and method that can use this inter-OD travel route information and complement roads where road beacons are not installed to estimate link travel time. .
[0007]
[Means for Solving the Problems]
  (1) In the link travel time estimation device of the present invention, the ground device collects the position information grasping means for grasping the position of the vehicle, the information collecting means for collecting the identification code information of the in-vehicle device, and the information collecting means. Based on the information on the identification code of the in-vehicle device and the position information of the vehicle grasped by the position information grasping means, the vehicle equipped with the in-vehicle deviceBetween two positionsDriving route specifying means for specifying the driving route by calculating the shortest route;A reference route calculating means for calculating a shortest time route between two positions of the vehicle based on a calculation criterion including a statistical link travel time;It was grasped based on the record of the time when communication between the in-vehicle device and the ground device was made.SaidVehicleBetween two positionsTransit timeAnd the travel time of the shortest time route calculated by the reference route calculation means, and if the comparison results in satisfying a certain standard, the transit time between the two positions of the vehicleTheseBetween two positionsLink travel time estimating means for estimating the travel time of the link by allocating the distance according to the distance ratio of the links constituting the travel route (claim 1).
[0008]
  According to the link travel time estimation device having this configuration, the ground device grasps the position of the vehicle and collects identification code information from the in-vehicle device. Based on the collected identification code of the in-vehicle device and information on the vehicle position, the travel route of the vehicle on which the in-vehicle device is mounted can be specified by performing the shortest route calculation process. AndIn order to judge whether or not the travel route of the vehicle specified by the travel route specifying means is a route on which the vehicle has actually traveled, the shortest time route is calculated by the reference route calculation means, and this shortest time is calculated. The travel time between the route and the identified vehicle travel route is compared. As a result of comparison, if certain criteria are met,The travel time of the link can be estimated by allocating the passing time between the two vehicle positions included in the travel route by the distance ratio of the links constituting the travel route.
The certain criterion is that the travel times of both routes have close values (claim 4).
[0009]
The link for which the travel time is estimated by the link travel time estimation means may be limited to a link for which link travel time information is not provided (Claim 2). This is because there is usually no need to estimate the travel time of a link provided with link travel time information.
Of course, even on a road where link travel time information is provided by some means, the link travel time obtained based on the vehicle travel route information is used to correct the existing link travel time information. Or update it.
[0010]
  In order to identify the travel route of the vehicle, the travel route specifying meansBased on link distance or on link distanceDoes not include statistical link travel timeotherCalculation criteriaCalculation standard withIt is desirable to calculate the shortest route based on the above and use it as the vehicle travel route (claim 3). This is because, when the shortest route is calculated in order to specify the travel route of the vehicle, if there is a road for which no link travel time information is provided, the link travel time data cannot be used for that road.The link distance data is completed as link data in almost all cases. The shortest path is calculated using a calculation criterion including the link distance.
[0013]
  The ground device includes a plurality of road communication devices that communicate with the vehicle-mounted device, and a center device that collects information on each road communication device, and the position information grasping means is installed on the road communication device through which the vehicle has passed. The vehicle position may be grasped based on the position information.5). This configuration relates to an embodiment of the present invention in which a road communication device is installed on a road and information such as an identification code of the in-vehicle device is collected by the road communication device.
[0014]
  Further, the position information grasping means may grasp the position of the vehicle by acquiring the position detection information of the vehicle from the in-vehicle device by communication.6). This configuration relates to an embodiment of the present invention that collects the vehicle position information and the identification code information of the in-vehicle device on the ground device by using the position detection function of the in-vehicle device.
  (2) The link travel time estimation method of the present invention is a method according to the same invention as the link travel time estimation device described in claim 1 (claim)7).
[0015]
  (3) In the present invention, it is preferable that the link travel time is estimated for a plurality of vehicles, and the travel time data of the obtained link is statistically processed.8). This is because a more accurate link travel time can be obtained by statistically processing the link travel times estimated for a plurality of vehicles.
  The link for estimating the travel time may be limited to a link that does not provide link travel time information and has a high traffic volume.9). This is because it is highly necessary to provide link travel time information for links with a large amount of traffic even though link travel time information is not provided. Further, even if the link travel time is statistically processed for a link with a small amount of traffic, good estimation accuracy cannot be obtained.
[0016]
  The determination of the “traffic link” is a claim.10It is preferable to carry out as described in (a) to (d). A link for which no information on the link travel time is provided is often a link in which no vehicle position information grasping means is installed, and therefore traffic volume cannot be measured. Therefore, the shortest route is calculated, and it is considered that the vehicle has passed through the links constituting the shortest route, and it is determined whether the traffic volume is small or small. This shortest path is, for example, the shortest distance path.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention that communicates with an in-vehicle device using a road beacon will be described in detail with reference to the accompanying drawings.
-Road beacon-
FIG. 1 is an installation diagram of a road beacon B that functions as a road communication device. The road beacon B has a light emitter / receiver B1 disposed at a position overlooking the road at the top of the pole, and a control device B2 installed beside the pole. The control device B2 is connected to a center device A described later by a wired communication line.
[0018]
The road beacon B is a road communication function that performs two-way communication with the in-vehicle device C using light of a predetermined wavelength, and irradiates a short pulse optical signal toward the road, and reflects the reflected light to the vehicle passing underneath. It has a vehicle detection function to detect passage. Note that the communication medium of the road beacon B is not limited to light, and may be radio waves.
FIG. 2 is a flowchart for explaining a procedure for transmitting data from the road beacon B to the center apparatus A when focusing on the road communication function.
[0019]
The road beacon B collects information from the in-vehicle device C in the storage device B2 (step S1). Data collected from the in-vehicle device C to the road beacon B includes data such as the vehicle identification code, vehicle type information, the code of the road beacon that has passed the previous time, and the travel time from the time when the front circuit beacon passed.
The identification code may be a code unique to a vehicle, an in-vehicle device, or an individual. Moreover, the code | cord | chord which the road beacon B generate | occur | produced and assigned by the random number at the specific timing may be sufficient, and the number assigned in order to the passing vehicle may be sufficient.
[0020]
If the fixed transmission cycle is reached (step S2), data is transmitted to the center apparatus A (step S3). The center device A accumulates the received information (step S4).
Table 1 shows a list of information collected from a plurality of road beacons B and accumulated in the center apparatus A. In Table 1, the display of the vehicle type, the beacon that passed last time, and the travel time data from the last passing time is omitted.
[0021]
[Table 1]

[0022]
―Road network―
FIG. 3 is an area map of a road network where road beacons, cameras, and the like are installed.
In this map, a plurality of roads are drawn vertically and horizontally, and there are intersections. The road between the intersections is regarded as one link unit, and uplink and downlink links L1 to LN (N = 48 in FIG. 3) are configured. Cross links between the links are intersection nodes N1, N2,..., N9.
[0023]
A road beacon is installed at a position where it enters an intersection from each link, and is indicated by a black triangle. Cameras are installed everywhere overlooking a certain range of roads. In addition, although the road beacon is drawn in FIG. 3 as being installed at each intersection, there is actually an intersection that is not installed. Moreover, it may be installed other than the position entering the intersection.
In addition, narrow streets are connected from the middle of the road, and parking lots of stores and houses exist along the road. In FIG. 3, narrow streets and parking lots are drawn only on some roads for the sake of drawing, but in reality, narrow streets are connected to most roads and parking lots exist.
[0024]
―Center device―
FIG. 4 is a functional block diagram in the center apparatus A. The center device A has an input conversion unit 1 that converts a transmission / reception signal to / from the road beacon B, an input conversion unit 2 that converts an image signal of the camera, and a point traffic volume (point Based on the traffic measurement unit 3 that calculates the number of vehicles per unit time passing through the vehicle, the transmission / reception signal of the road beacon B and the image signal of the camera, the vehicle identification code, the passage time, the vehicle type, the road beacon that passed the previous time Data, travel time data from the time when it passed the beacon on the previous circuit is acquired and the data totaling unit 4 that stores the data in the memory, the data stored in the memory of the data totaling unit 4 is taken out, and the travel between ODs based on the data The OD travel route calculation unit 5 for obtaining the route calculates the OD traffic volume (Q1) by statistically processing the travel route between the ODs, and also calculated by the traffic measurement unit 3 OD traffic volume estimation unit 6 that calculates OD traffic volume (Q2) based on the traffic volume at the point, and estimates the final OD traffic volume (Q) based on both OD traffic volumes (Q1, Q2) A link travel time estimation unit 7 that estimates the link travel time based on the inter-OD travel route is provided. The cylindrical shape in FIG. 4 shows the memory belonging to each part.
[0025]
The center device A includes a computer, a memory, an input / output device, and the like, and is performed by the traffic volume measuring unit 3, the data totaling unit 4, the OD travel route calculating unit 5, the OD traffic amount estimating unit 6, and the link travel time estimating unit 7. All or part of each processing function is realized by a computer executing a program recorded in the memory.
Hereinafter, each process performed by the traffic volume measurement unit 3, the OD travel route calculation unit 5, the OD traffic volume estimation unit 6, and the link travel time estimation unit 7 will be described in order using a flowchart if necessary.
[0026]
-Traffic measurement-
The traffic volume measuring unit 3 calculates the point traffic volume (the number of vehicles passing per unit time (for example, 5 minutes)) based on the sensing signal of the road beacon B obtained from the input conversion unit 1. Since the road beacon B is installed for each link, the point traffic is also obtained for each link. Therefore, it is hereinafter referred to as “link point traffic volume”.
Furthermore, the traffic volume measuring unit 3 detects the occupation time O (the total sum Σtk of the times tk when each vehicle k crosses the vehicle detector within a unit time (for example, 5 minutes)).
[0027]
Moreover, the traffic volume measurement part 3 measures a link travel time as follows.
Using the point traffic volume measurement q, occupation time O, and average vehicle length (constant value) I, the vehicle average speed V is calculated by the formula V = I · q / O, and the link length Using L, the link travel time T is calculated by the formula T = L / V.
In addition, the vehicle plate number is matched from the camera measurement image to identify the vehicle, and it is necessary to travel the link from the time when the same vehicle passes the link end and the other end of the link. Time T 'is obtained. If there are a plurality of vehicles passing through the unit time, the average of the link travel times T ′ of the vehicles is taken.
[0028]
Then, either the link travel time T or the link travel time T ′ obtained as described above, or the weighted average of these is taken as the link travel time. Note that a filter value may be used to absorb travel time measurement errors. Since there are variations depending on the day of the week, time zone, weather, etc., past statistical values may be taken into account.
-OD travel route calculation-
FIG. 5 is a flowchart for explaining an OD travel route calculation process performed by the OD travel route calculation unit 5.
[0029]
First, the vehicle identification code, passage time, vehicle type, road beacon code that passed the previous time, travel time data from the time when the previous circuit beacon passed (Table 1) ) Is acquired (step V1). The data is sorted for each identification code and stored in the memory (step V2). This information is called “basic information”.
Table 2 is a list of basic information. According to Table 2, for example, the vehicle information of the identification codes “1”, “2”,..., “123” is grouped together.
[0030]
[Table 2]

[0031]
The identification code data of the same vehicle is extracted from the basic information (step V3). Based on the data of the identification code of the same vehicle, the road beacons that have passed are rearranged in order of passing time (step V5). Thereby, the road beacon which passed can be specified in order of passage. In addition, the road beacon that has passed the earliest and is flagged as “no beacon that passed last time” represents the generation point (O) of the vehicle, and the road beacon that passed at the latest time point indicates the disappearance point (D) of the vehicle. Represent.
[0032]
Next, a travel route between the beacons on the passing route is obtained (step V7). Since the road beacon B is usually installed at each intersection as shown in FIG. 3, the traveling route between the beacons on the road is a road connecting the intersections. However, when the road beacon B is not installed at each intersection or when the vehicle passes through a road where the road beacon B is not installed, the travel route is not uniquely determined. Based on the above, the shortest distance route (A) based on the link distance between the beacons on the passing route is calculated (see, for example, JP-A-7-244798).
[0033]
If the data includes the information “no previous road beacon passed”, this is regarded as the vehicle generation point (O), and the vehicle travel route investigation of the identification code is terminated (step). V6 NO). In this case, the process returns to step V3, and an investigation for basic information on other identification codes (that is, other vehicles) is started.
As described above, since the shortest distance route information between the ODs of the respective vehicles is obtained, it is stored in a predetermined memory (step V8).
[0034]
-Link travel time estimation-
FIG. 6 is a flowchart for explaining the link travel time estimation process performed by the link travel time estimation unit 7.
First, it is examined whether or not the shortest distance route (A) between ODs includes a link for which link travel time information is not provided (hereinafter referred to as “traffic information non-providing link”) (step V9). When including a link that does not provide traffic information, only the link that provides link travel time information (hereinafter referred to as “traffic information providing link”) is used as a reference route and the shortest time route between ODs (B). Calculate (step V10).
[0035]
When the traffic information non-providing link is not included, that is, when the shortest distance route (A) between ODs is composed only of the traffic information providing link, the shortest time route (B) between ODs is calculated (step V10). This considers the need to update the travel time information by the link travel time estimation processing of the present invention, although the travel time of the traffic information providing link has already been obtained. However, since the travel time of the traffic information providing link is obtained by another method, it is possible to select not to perform the link travel time estimation processing of the present invention. In this sense, a note) is shown in FIG.
[0036]
Next, proceeding to step V11, the travel time TA between the OD points measured by the shortest distance route (A) between the ODs and the travel time TB between the OD points measured by the shortest time route (B) between the ODs are obtained. Compare.
It is determined whether or not these travel times TA and TB satisfy a certain standard (described later) (step V12). If the certain time is satisfied, the vehicle has traveled the shortest distance route (A) between the ODs. Assuming that the possibility is high, the link travel time of the link constituting the shortest distance route (A) between the ODs is estimated, and the value is stored (step V13). If the vehicle does not meet a certain standard, it is unlikely that the vehicle has traveled the shortest distance route (A) between ODs. Therefore, link travel time estimation processing of the links constituting the shortest distance route (A) between ODs is performed. Absent.
[0037]
The link travel time is estimated in the same manner for other vehicles, and link travel time data is accumulated. If the accumulated link travel time data is statistically processed (for example, averaged), a more accurate link travel time can be obtained. This link travel time can be used as basic data for route calculation (step V14).
Hereinafter, this link travel time estimation process will be described in more detail using a specific example.
[0038]
Calculation of Shortest Distance Route (A): FIG. 7 is a road map for explaining a method for calculating the shortest distance route (A). The beacons 42, 27, and 20 represent the beacon numbers that the vehicle of the vehicle identification code 123 of Table 2 has passed. Further, the thick road in FIG. 7 represents a road corresponding to the traffic information providing link, and the thin road represents a narrow street corresponding to the traffic information non-providing link. If the shortest distance route (A) that has passed through these beacons 42, 27, and 20 in order is calculated, the route indicated by the broken line in FIG. This route is a route including narrow streets, that is, traffic information non-providing links La and Lb. As a reference for calculating the shortest distance route (A), in addition to the link distance, right / left turn limit, right / left turn cost, presence / absence of highway / highway driving designation, traffic regulation for the relevant vehicle type, road width Standards such as these may be added as appropriate.
[0039]
Calculation of the shortest time route (B): FIG. 8 is a road map for explaining a method for calculating the shortest time route (B). Only the beacon 42 at the vehicle generation point and the beacon 20 at the vehicle disappearance point are illustrated. In calculating the shortest time route (B), only the traffic information providing link, that is, the thick road in FIG. As the link cost, the link travel time already obtained by traffic measurement or the like is used. This shortest time path (B) is indicated by a broken line in FIG. As a reference for calculating the shortest time route (B), in addition to the link travel time, right / left turn limit, right / left turn cost, presence / absence of designation of expressway / highway driving, traffic regulation for the relevant vehicle type, road Criteria such as width may be added as appropriate.
[0040]
Travel time TA measured by the shortest distance route (A): This travel time TA is obtained from the difference between the passing time of the beacon 42 and the passing time of the beacon 20 of the vehicle. Specifically, referring to Table 2, the time when vehicle 123 passed beacon 42 was 8:20:25, and the time when vehicle 123 passed beacon 20 was 8:50:58. This difference 1833 seconds is the travel time TA.
Travel time TB calculated with the shortest time route (B): This travel time TB is the sum of the link travel times used to obtain the shortest time route (B).
[0041]
Comparison of travel time TA and travel time TB: The distance ratio LA / LB between the distance LA of the shortest distance route (A) and the distance LB of the shortest time route (B) is obtained, and this distance ratio is multiplied by the travel time TB. Convert to the travel time of the shortest distance route (A). A ratio between the converted travel time and the travel time TA is taken, and it is determined whether or not the ratio is within a certain range including 1. If it is within a certain range including 1, it is assumed that the certain criterion of Step V12 is satisfied. The certain range is a range that is empirically obtained after actually operating the system. For example, the range from 0.5 to 2.0 can be illustrated.
[0042]
Estimating the link travel time of the links constituting the shortest distance route (A): The travel time between the beacons that have passed is allocated by the link distance ratio to estimate the link travel time.
The following two methods 1 and 2 can be considered.
Method 1 The link travel time is estimated by dividing the distance of the link for which the link travel time is to be obtained by the distance between the beacons that have passed and multiplying the distance by the distance between the beacons. For example, referring to FIG. 7, the distance of the link La for which the link travel time is to be obtained is divided by the distance between the beacons 42 and 27 that have passed, and the passing time between the beacons 42 and 27 (8:41:25). Second-8:20:25) to estimate the link travel time of the link La.
[0043]
Method 2 The travel time related to the traffic information providing link is obtained using the known link travel time obtained by traffic volume measurement or the like. And the link travel time of a traffic information non-provision link is estimated by subtracting the travel time concerning a traffic information provision link from the travel time between the beacons which passed. For example, referring to FIG. 7, the travel time from the occurrence point O to X is obtained by using the known link travel time as the travel time from Y to the extinction point D, and this time is calculated from the transit time between the beacons 42 and 27. By subtracting the travel time related to the traffic information providing link, the link travel time of the link La and the link Lb is estimated. The link travel time of the link La and the link travel time of the link Lb are obtained by allocating the distance ratio.
[0044]
Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments. For example, the vehicle-mounted device has a vehicle position detection function such as GPS (Global Positioning System), and the identification code and the vehicle detection position information are taken into the ground device from the vehicle-mounted device, and the ground device is similar to the center device A described above. It is also possible to obtain the travel route between OD of each vehicle and to estimate the link travel time based on the travel route between ODs. In this case, communication between the in-vehicle device and the ground device may be performed regularly or irregularly using a mobile phone, a car phone, or a dedicated line.
[0045]
Further, in the description so far, in the link travel time estimation process of FIG. 6, when the shortest distance route (A) between ODs includes a traffic information non-providing link regardless of the traffic volume, the traffic information non-providing link About seeking link travel time.
However, if the traffic volume is small, the link travel time data obtained is also small, so even if statistical processing is performed, a link travel time with high accuracy cannot be obtained. Even if the shortest time route is calculated using the data of link travel time with inaccuracy, the correct route cannot be obtained. The processing amount of the center apparatus A is also finite.
[0046]
Therefore, it is desirable to perform link travel time estimation processing only for traffic information non-providing links with a large amount of traffic.
Hereinafter, a method for determining a link with a large traffic volume performed by the center apparatus A will be described.
FIG. 9 is a road network map, in which traffic information providing links are drawn with solid lines, and traffic information non-providing links are drawn with broken lines. It is assumed that beacons Ba to Bf are installed at each intersection of the traffic information providing link. A vehicle generation point (O) and a vehicle disappearance point (D) are represented by dots.
[0047]
As long as the vehicle travels on the traffic information provision link, each beacon passes in order from the occurrence point O to the disappearance point D.
10 and 11 are flowcharts for explaining a method for determining a link with a large traffic volume. First, data of the same vehicle number is extracted from the basic information (step W1), and two beacons that the vehicle has passed are continuously extracted (step W3).
[0048]
Referring to the road network map (FIG. 9) (step W6), it is determined whether or not the traffic information providing link that has passed is broken (step W7). This determination method will be described with reference to FIG.
(A) When the beacon passed subsequently is, for example, from Ba to Bb, Ba and Bb are connected by the traffic information providing link, and the route is connected by the traffic information providing link between Ba and Bb. There are no other beacons. In this case, it is determined that the vehicle has traveled on the traffic information providing link.
[0049]
(B) If the beacon that has passed subsequently is, for example, Ba to Be, even if a route that connects between them by any traffic information providing link is obtained, it passes through other beacons Bb and Bd. At this time, it is determined that the traffic information providing link between Ba and Be is interrupted. That is, if any traffic information providing link is connected between two beacons and there is another beacon between them, the vehicle does not pass a beacon that should have passed between them. Determines that the vehicle has traveled on the traffic information non-providing link.
[0050]
When it is determined that the vehicle has traveled on the traffic information non-providing link, the process proceeds to step W8 to calculate the shortest distance route between the two beacons. Of course, the range of the shortest distance route calculation includes not only the traffic information providing link but also the traffic information non-providing link. Then, it is confirmed whether or not the traffic information providing link is included in the calculated shortest distance route (step W9), and if it is not included, there is a high possibility that the vehicle has traveled the shortest distance route. Therefore, 1 is added to the links constituting the shortest distance path. If a plurality of links constituting the shortest distance path are connected in series, 1 is added to each. (Step W10).
[0051]
If the traffic information provision link is included in the shortest distance route calculated in step W9, it is considered that the vehicle is likely to have passed the beacon halfway. The possibility that the user has traveled the calculated shortest distance route is low.
Such a process is performed between the ODs of the vehicle, and when the process is completed for the vehicle, the process is also performed for the other vehicles.
[0052]
When all the vehicles in the basic information have been processed, only the traffic information non-providing links whose number of passing units per unit time is over a certain level are marked. This determination threshold is determined from experience.
The link travel time estimation process described above is performed only for the marked traffic information non-providing link.
[0053]
【The invention's effect】
As described above, according to the present invention, it is possible to accurately estimate the link travel time of the links constituting the shortest route by connecting the passing positions of the vehicles with the shortest route. Therefore, the estimated link travel time can be used for the shortest time route calculation.
[Brief description of the drawings]
FIG. 1 is a layout diagram of a road beacon B. FIG.
FIG. 2 is a flowchart illustrating a procedure for transmitting data from a road beacon B to a center device.
FIG. 3 is an area map of a road network where road beacons B, cameras, and the like are installed.
FIG. 4 is a functional block diagram of the center device.
FIG. 5 is a flowchart for explaining an OD travel route calculation process performed by an OD travel route calculation unit 5;
FIG. 6 is a flowchart for explaining link travel time estimation processing performed by a link travel time estimation unit 7 (continuation of FIG. 5).
FIG. 7 is a road map for explaining a method of calculating a shortest distance route (A).
FIG. 8 is a road map for explaining a method of calculating a shortest time route (B).
FIG. 9 is a road network map including a traffic information providing link, a traffic information non-providing link, and a beacon.
FIG. 10 is a flowchart for explaining a method for determining a link with a large traffic volume;
FIG. 11 is a flowchart (continuation of FIG. 10) for explaining a method for determining a link with a large amount of traffic.
[Explanation of symbols]
1 Input converter
2 Input converter
3 Traffic volume measurement unit
4 data aggregation department
5 OD travel route calculator
6 OD Traffic Estimator
7 Link travel time estimation part
A Center device
B Road beacon
B1 Emitter / receiver
B2 control device
C In-vehicle device

Claims (10)

A link travel time estimation apparatus for estimating link travel time based on the communication between the car mounting device and the ground device,
The ground device is
Position information grasping means for grasping the position of the vehicle;
Information collecting means for collecting information on the identification code of the in-vehicle device;
Based on the information of the identification code of the in-vehicle device collected by the information collecting means and the position information of the vehicle grasped by the position information grasping means , the travel route between the two positions of the vehicle equipped with the in-vehicle device is determined as the shortest. Driving route specifying means for specifying by calculating the route;
A reference route calculating means for calculating a shortest time route between two positions of the vehicle based on a calculation criterion including a statistical link travel time;
Comparison vehicle apparatus and passing time between two positions of the vehicle communicate with the ground device is grasped based on the recording time has been made and, the travel time of the reference path calculating means shortest time path calculated by When the comparison results in satisfying a certain standard, the passing time between the two positions of the vehicle is distributed by the distance ratio of the links that constitute the travel route between the two positions. A link travel time estimation means for estimating the travel time of the link;
A link travel time estimation device comprising:   The link travel time estimation device according to claim 1, wherein the link whose travel time is estimated by the link travel time estimation means is a link for which link travel time information is not provided. The travel route specifying means calculates the shortest route based on the link distance or based on a calculation criterion obtained by adding another calculation criterion not including the statistical link travel time to the link distance . The link travel time estimation device according to claim 1, wherein the link travel time estimation device is a travel route. The fixed reference is the link travel time estimation apparatus according to claim 1, wherein the travel time of the two paths is to have close values. The ground device includes a plurality of road communication devices for communicating with a vehicle-mounted device, and a center device that collects information on each road communication device,
The link travel time estimation device according to claim 1, wherein the position information grasping means grasps the position of the vehicle based on the installation position information of the on-road communication device through which the vehicle has passed.   The link travel time estimation device according to claim 1, wherein the position information grasping means grasps the position of the vehicle by acquiring vehicle position detection information from the in-vehicle device by communication. Based on the communication between the car mounting device and ground apparatus a link travel time estimation method for estimating the link travel time,
For the same vehicle, determine the travel route of the vehicle by calculating the shortest path between based rather two positions for communication between the in-vehicle equipment and a device,
Calculate the shortest time path between the two positions of the vehicle based on a calculation criterion that includes statistical link travel time;
The transit time between the two positions of the vehicle obtained based on the record of the time when the vehicle-mounted device and the ground device communicated is compared with the calculated travel time of the shortest time route, and the comparison result is constant. The travel time of the link is estimated by allocating the passing time between the two positions of the vehicle according to the distance ratio of the links constituting the travel route of the vehicle when the above-mentioned criteria are satisfied. Link travel time estimation method.   The link travel time estimation apparatus according to claim 1, wherein the link travel time is estimated for a plurality of vehicles, and the travel time data of the obtained link is statistically processed. The link travel time estimation device according to claim 8 , wherein the link for estimating the travel time is a link for which information on the link travel time is not provided, and is limited to a link with a large amount of traffic. 10. The link travel time estimation device according to claim 9, wherein the determination of the “link with a large amount of traffic” is performed as follows.
(A) Based on the identification code information and position information of a certain vehicle, the passing position of the vehicle is tied, and when the link for which the link travel time information is provided is broken, The shortest path is calculated for the interrupted portion.
(B) The vehicle is considered to have passed through the link constituting the shortest route, and 1 is added to the number of passing links.
(C) The processes (a) and (b) are performed for other vehicles.
(D) A link in which the total number of passing vehicles exceeds the threshold is determined as a “link with a large amount of traffic”.

Images