JP3709008B2 - Route calculation apparatus and route calculation method - Google Patents

Description

【００３５】
有効時間帯Ｚ_k とは、１日あたり多数に区切られた「時間帯」のうちから複数選ばれたもので、計算開始リンクのリンクコストとして、この有効時間帯Ｚ_k の統計リンクコストＴ_S (t) を採用し、それからつながるリンクについて経路探索を行う。
例えば２５１番目のリンクについては、番号２，９，１４，３２等の時間帯が記録されているので、経路探索にあたっては、計算開始リンクの統計リンクコストＴ_S (t) として、番号２の時間帯の統計リンクコストＴ_S (t) を採用して、それからつながるリンクについて経路探索を行い、番号９の時間帯の統計リンクコストＴ_S (t) を採用して、それからつながるリンクについて経路探索を行い、番号１４の時間帯の統計リンクコストＴ_S (t) を採用して、それからつながるリンクについて経路探索を行い、以下同様に続ける。
【００３６】
コントローラ１６には、目的地及び各種計算条件を入力するためのリモートコントローラキー（以下単に「リモコンキー」という）４が入力制御部１３を介して接続されている。リモコンキー４には、例えば地図のスクロール、位置の設定、メニューの選択を行う「ジョイスティック／セットキー」、現在地を表すカーマークを中心とする道路地図画面を表示させる「地図キー」、道路地図の表示スケールを拡大縮小する「縮尺キー」、車両の進行方向を上に表示するか、地図の北を上に表示するかを選択する「回転キー」、車両の走行軌跡を表示するかしないかを切換える「軌跡キー」、現在地から目的地までの最短時間経路を算出させたいときにワンタッチで経路計算指示信号を入力できる「ルートキー」、「目的地設定」，「ルート設定」などのメニュー画面を表示させる「メニューキー」、メニュー操作時１つ前の画面に戻す「リターンキー」等の各種のキー（いずれも図示せず）が備えられている。
【００３７】
コントローラ１６は、ユーザによりリモコンキー４を介して目的地及び各種計算条件（有料道路を優先するか否か、フェリー利用を優先するか否か、又は経由地を経由するか否か、など）が入力されると、この入力された目的地データ等をＳＲＡＭ１６２に記憶するとともに、車載地図専用ディスクＤから経路計算用道路地図データを読出し、目的地及び車両位置検出部１４で検出された現在地にそれぞれ近いリンク間の最短時間経路を例えばダイクストラ法又はポテンシャル法を用いて算出する。算出された最短時間経路は、ディスプレイ３に表示されている道路地図上に例えば破線で重畳表示される。
【００３８】
ここで、前記ポテンシャル法とは次のような方法である。すなわち、出発地（目的地でもよい）に近いリンクを計算開始リンクとし、目的地（出発地でもよい）に最も近いリンクを計算終了リンクとし、ユーザにより入力された各種計算条件に基づいて、計算開始リンクから始まる所定地図領域内のリンクをすべて探索する。このとき、各リンクの統計リンクコストＴ_S (t) 又は旅行時間予測値Ｔ_P (t) （後述する）を順次加算し、最短でない経路は切捨て、最短経路を実現する経路のみを残すという処理を繰り返す。その結果、最終的に、最短経路のみからなる経路のトリーが得られるので、計算終了リンクから計算開始リンクまでの経路を逆に辿っていけば、最短時間経路を得ることができる。
【００３９】
コントローラ１６にはまた、ビーコン受信機７が接続されている。ＣＰＵ１６１は、車両が路上ビーコンＡの送信エリア内に進入して（図１参照）、路上ビーコンＡから送信されている一連の最新のリンク交通情報がビーコン受信機７で受信されると、当該リンク交通情報をＳＲＡＭ１６２に与えて保持させる。ＣＰＵ１６１では、前記方法によって最短時間経路を算出する際、ＳＲＡＭ１６２にリンク交通情報が保持されている場合には、前記経路計算用道路地図データに含まれている統計リンクコストＴ_S (t) に、当該リンク交通情報を利用して求めたリンクコスト（以下「リアルタイムリンクコスト」という）を加味して予測リンクコストＴ_P (t) を求め、この予測リンクコストＴ_P (t) に基づいて複数の経路を算出する。ＳＲＡＭ１６２にリンク交通情報が保持されていない場合には、統計リンクコストＴ_S (t) をそのまま用いて複数の経路を算出する。
【００４０】
図５から図８は、前記車載ナビゲーション装置１における複数の経路の算出処理を説明するためのフローチャートである。
ユーザは、走行前又は走行中に、リモコンキー４を操作して目的地や経由地（以下代表して「目的地」という）を入力する。コントローラ１６は、車両位置検出部１４で検出された現在地に最も近いリンクを計算開始リンクとし、目的地に最も近いリンクを計算終了リンクとする（図５のステップＳ１）。
【００４１】
次に、現在時刻を参照して、現在時刻の属する出発時間帯Ｚ₀ を特定する（ステップＳ２）。そして、前述した利用テーブルを参照して、計算開始リンクに対応する、現在時刻の属する出発時間帯Ｚ₀ 以後の時間帯を順にチェックし（ステップＳ３）、ヒットした時間帯すなわち有効時間帯Ｚ_k を複数特定する（ステップＳ４）。
【００４２】
そしてコントローラ１６は、計算開始リンクから始まる所定地図領域内のリンクをすべて探索する。
この探索にあたり、まず初めに統計リンクコストＴ_S (t) をそのまま用いて複数の経路を算出する方法を説明し、その後ＳＲＡＭ１６２にリンク交通情報が保持されていて、当該リンク交通情報を利用して求めたリンクのリアルタイムリンクコストを加味して予測リンクコストＴ_P (t) を求め、この予測リンクコストＴ_P (t) に基づいて複数の経路を算出する方法を説明する。
＜統計リンクコストＴ_S (t) をそのまま用いて複数の経路を算出する方法＞
この方法では、所定地図領域内のリンクのリンクコストとして、リンクごとにそれぞれ異なった時間帯に属する統計リンクコストＴ_S (t) を用いる。
【００４３】
詳しく説明すると、有効時間帯Ｚ_k のうち、時間の最も早い有効時間帯Ｚ₁ をまず選定して、計算開始リンクのリンクコストを、有効時間帯Ｚ₁ の統計リンクコストＴ_S (t) とする。
次に、この計算開始リンクに続くリンクについては、計算開始リンクの有効時間帯Ｚ₁ よりも計算開始リンクのリンクコスト分だけ遅い有効時間帯、すなわち車両が当該リンクに到達するであろうと考えられる時間帯を決定し、当該有効時間帯に属する統計リンクコストＴ_S (t) をリンクコストとして用いる。
【００４４】
これにつながるリンクについても、同様にして、リンクコストを加算していって、車両が当該リンクに到達するであろうと考えられる時間帯の統計リンクコストＴ_S (t) をリンクコストとして用いて、経路を探索する（ステップＳ５）。
なお、車両が当該リンクに到達するであろうと考えられる時間帯の統計リンクコストＴ_S (t) をリンクコストとして用いる代わりに、所定地図領域内の全てのリンクについて、一様に、計算開始リンクの有効時間帯Ｚ₁ と同一の時間帯Ｚ₁ の統計リンクコストＴ_S (t) をリンクコストとして用いてもよい。
＜リアルタイムリンクコストと統計リンクコストＴ_S (t) を併用して複数の経路を算出する方法＞
リアルタイムリンクコストをそのまま用いて経路を求めるのでは、リアルタイムリンクコストの瞬時的変動が激しすぎるので、この方法では、これを平滑化するため、統計リンクコストＴ_S (t) を加味した指数平滑手法を用いて予測リンクコストＴ_P (t) を求め、この予測リンクコストＴ_P (t) をリンクコストとして用いて所定地図領域内の経路を探索する。
【００４５】
この指数平滑手法では、当該経路計算対象リンクと外部から得られたリンクとが図３(a) に示すように１対１に対応している場合、前記外部から得られたリンクに対応する統計リンクコストＴ_S (t) をＳＲＡＭ１６２から読出すとともに、統計リンクコストＴ_S (t) を修正するために必要な誤差予測値ｅ_t を求める。
前記誤差予測値ｅ_t は、その初期値は０とするが、リアルタイムリンクコストの瞬時的変動が激しすぎるのでこれを平滑化して用いるという目的を考慮すると、予測リンクコストＴ_P (t) の瞬時的変動を吸収する必要がある。このため、同一の外部から得られたリンクのリアルタイムリンクコストに基づいて採用した誤差予測値ｅ_t-1 を考慮して重み付けした平均をとって誤差予測値ｅ_t とする。
【００４６】
より具体的に説明すると、予測リンクコストＴ_P (t) が得られると、予測リンクコストＴ_P (t) と、当該外部から得られたリンクの統計リンクコストＴ_S (t) との差を求める。
次に、メモリに保持されている、同一リンクの前の時点の予測リンクコストＴ_P (t−1)を読み出し、このリンクの統計リンクコストＴ_S (t) との差をとり、誤差予測値ｅ_t-1 を求め、下記(1) 式のようにして新たな誤差予測値ｅ_t に更新する。
【００４７】
ｅ_t ＝α（Ｔ_P (t) −Ｔ_S (t) ）＋（１−α）ｅ_t-1 ‥‥(1)
ただし、前記(1) 式において、α（０＜α＜１）は平滑指数であって、０に近ければ、過去の誤差予測値ｅ_t-1 に重みをおき、１に近ければ、現在の予測リンクコストＴ_P (t) に重みをおいている。例えばα＝０．８にとっている。
このようにして求められた誤差予測値ｅ_t を使って、下記(2) 式のようにして当該経路計算対象リンクに対応する予測リンクコストＴ_P (t) を算出する。
【００４８】
Ｔ_P (t) ＝ｅ_t ＋Ｔ_S (t) ‥‥(2)
なお、前記の説明では、予測リンクコストと統計リンクコストとの差に着目していたが、予測リンクコストと統計リンクコストとの比に着目してもよい。この場合は前記(3) 式(4) 式は、それぞれ次のようになる（ｅ_t の初期値は１）。
【００４９】
ｅ_t ＝α（Ｔ_P (t) ／Ｔ_S (t) ）＋（１−α）ｅ_t-1 ‥‥(3)
Ｔ_P (t) ＝ｅ_t ・Ｔ_S (t) ‥‥(4)
また、図３(b) に示すように、当該リンクが外部から得られたリンクの一部として含まれている場合には、前記(2) 式又は(4) 式に基づいて予測リンクコストＴ_P (t) が算出された後、下記(5) 式の演算が行われ、当該経路計算対象リンクに対応する予測リンクコストＴ_P (t) が算出される。ただし、下記(5) 式において、ｄ_Niは当該リンク_i のリンク長、ｄ_K は前記外部から得られたリンクのリンク長を表す。
【００５０】
（ｄ_Ni／ｄ_K ）×Ｔ_P (t) →Ｔ_P (t) ‥‥(5)
前記(2) 式若しくは(4) 式又は(5) 式で算出された予測リンクコストＴ_P (t) は不揮発性メモリに保持される。
このように、誤差予測値ｅ_t は、リアルタイムリンクコストの瞬時的変動を吸収するために求められるので、誤差予測値ｅ_t を用いて得られた予測リンクコストＴ_P (t) は、現在の交通状況を反映するとともに、実際の交通状況の極端な変動を抑えた値となっている。したがって、この予測リンクコストＴ_P (t) を用いて所定地図領域内の経路を探索する（ステップＳ５）。
【００５１】
経路の探索が終わると、計算終了リンクから計算開始リンクまでの経路を逆に辿っていき、経路Ｌ₁ を特定し記憶する（ステップＳ６）。
さらに、利用テーブルにヒットした有効時間帯Ｚ_k のうち、次に時間の早い有効時間帯Ｚ₂ を選定して、前記＜統計リンクコストＴ_S (t) をそのまま用いて複数の経路を算出する方法＞又は＜リアルタイムリンクコストと統計リンクコストＴ_S (t) を併用して複数の経路を算出する方法＞を用いて経路探索を行い、経路Ｌ₂ を特定し記憶する。このようなことを繰り返して、有効時間帯Ｚ_n (n=1,2,3, ‥‥,m) に対応する複数の経路Ｌ_n (n=1,2,3, ‥‥,m) を特定する。全有効時間帯Ｚ_k のチェックが終了すると、ステップＳ７からステップＳ１１（図６）に移り、記憶された複数の経路Ｌ_n (n=1,2,3, ‥‥,m) を順に取り出し、差異率Ｄをチェックする。
【００５２】
この差異率Ｄというのは、各経路Ｌ_n (n=1,2,3, ‥‥,m) から任意の２つの経路Ｌ_i ，Ｌ_j を取り出し、それらについてリンクコスト（例えば統計リンクコストＴ_S (t) ）を総和して経路旅行時間Ｔ_i ，Ｔ_j を求め、さらに経路Ｌ_i ，Ｌ_j の重なり部分の経路旅行時間Ｔ_ijを求め、これらを使って、
Ｄ_ij＝１−２Ｔ_ij／（Ｔ_i ＋Ｔ_j ）
で表される関数である。この差異率Ｄ_ijをしきい値と比較し（ステップＳ１２）、差異率Ｄ_ijがしきい値よりも小さければ（ステップＳ１３）、経路旅行時間の長いほうの経路を抹消して、ステップＳ１１に戻り、他の経路について処理を繰り返す。このようにして、差異率Ｄ_ijがしきい値より大きな経路のみが選定される（ステップＳ１４）。記憶した全ての経路Ｌ_n (n=1,2,3, ‥‥,m) について処理が終了すると（ステップＳ１５）、ステップＳ２１（図７）に進む。
【００５３】
なお、上の説明では、差異率Ｄは経路旅行時間Ｔ_i ，Ｔ_j ，Ｔ_ijに基づいて算出したが、経路距離に基づいてもよい。また、差異率Ｄを計算する代わりに絶対的な差異（Ｔ_i ＋Ｔ_j ）／２−Ｔ_ijを計算し、しきい値と比較してもよい。
ステップＳ２１以後では、選定した各経路（これを経路Ｌ_p と書く）を構成するリンクについて、リンク旅行時間を計算する。このリンク旅行時間の計算にあたっては、車両が当該リンクに到達するであろうと考えられる時間を決定してリンク旅行時間を求め、このリンクにつながるリンクについては、時間をずらしながら、一連のリンクのリンクコストの加算を行う（この考え方は、経路探索のときと同じである）。
【００５４】
まず、１つの経路について、計算開始リンクから順に処理を進める（ステップＳ２２）。
当該リンクについて、予測リンクコストＴ_P (t) が得られているかどうかをチェックする（ステップＳ２３）。
得られていなければ、統計リンクコストＴ_S (t) を採用して、これを通常旅行時間とする（ステップＳ２４）。さらに、通常旅行時間に（１＋ｂ）をかけて、これを最大旅行時間とする（ステップＳ２５）。最大旅行時間は、通常よりも多めに見積もってこれ位の時間がかかることをユーザに示すために計算するものである。ｂは、統計リンクコストＴ_S (t) の信頼性が高いほど小さくし、統計リンクコストＴ_S (t) の信頼性が低い程大きくする。通常ｂ＝０．１から０．２程度にとる。
【００５５】
当該リンクについて、予測リンクコストＴ_P (t) が得られていれば、予測リンクコストＴ_P (t) を採用して、これを通常旅行時間とする（ステップＳ２６）。さらに、通常旅行時間に（１＋ａ）をかけて、これを最大旅行時間とする（ステップＳ２７）。ａは、予測リンクコストＴ_P (t) の信頼性が高いほど小さくし、予測リンクコストＴ_P (t) の信頼性が低い程大きくする。通常ａ＝０．１から０．２程度にとる。
【００５６】
１つの経路Ｌ_P を構成するすべてのリンクについて処理が終われば（ステップＳ２８）、ステップＳ３１（図８）に進む。
ステップＳ３１では、当該経路Ｌ_p について、通常旅行時間を合計し、これを経路旅行時間とする（ステップＳ３１）。また最大旅行時間を合計し、これを経路最大旅行時間とする（ステップＳ３２）。
【００５７】
なお、前述の予測リンクコストＴ_P (t) を主体として旅行時間を求める方法以外に、予測リンクコストＴ_P (t) は無視して、統計リンクコストＴ_S (t) のみに基づいて旅行時間を計算することもできる。
他の経路Ｌ_p についてもステップＳ２１以下の処理をし、すべての経路Ｌ_p について処理が終われば（ステップＳ３３）、得られた経路Ｌ_P の個数が一定個数ｃを超えるかどうか判定する（ステップＳ３４）。一定個数ｃを超えていれば、経路旅行時間の小さい順にｃ個の経路（これを経路Ｌ_Q と書く）を最終選定する（ステップＳ３６）。一定個数ｃを超えていなければ、全部の経路Ｌ_P を経路Ｌ_Q として最終選定する（ステップＳ３５）。
【００５８】
そして、最終選定した経路Ｌ_Q を表示する（ステップＳ３７）。この表示は、最終選定した経路Ｌ_Q を一度に全部表示してもよいし、いずれか１本の経路Ｌ_Q を表示して、ユーザの要求があれば他の経路Ｌ_Q に切り換えるようにしてもよい。
また、経路旅行時間と、経路最大旅行時間も表示する（ステップＳ３８）。この表示をする場合は、単なる経路旅行時間であるか、経路最大旅行時間であるかに応じて表示の仕方を変えることが望ましいのは、勿論のことである。
【００５９】
そして、当該経路に対応する誘導指示情報を作成する。この経路に対応する誘導指示情報の内容としては、目的地までの方向、目的地までの直線距離、経路に沿った経路距離、交差点模式図等、従来より知られている色々なものがあり、これらのいずれか又はすべての情報がユーザに提供される。提供の方法は、ディスプレイ３に文字や矢印を表示させてもよく、スピーカＭから音声で誘導させてもよい。
【００６０】
本発明の実施例の説明は以上のとおりであるが、本発明は上述の実施例に限定されるものではない。例えば前記実施例では、複数経路の算出を車載ナビゲーション装置で行っていた。しかし、情報センターＣ等の地上系のシステムで複数経路の算出を行い、路上ビーコンＡを通して各車両に提供するものであってもよく、また、ユーザがオフィス等に設置されたパーソナルコンピュータを使って複数経路の算出を行ってもよい。
【００６１】
その他本発明の範囲内において種々の設計変更を施すことは可能である。
【００６２】
【発明の効果】
以上のように請求項１又は請求項９記載の発明によれば、利用テーブルを用いて、利用テーブルで指定された複数の時間帯を取得し、それぞれ取得された時間帯に関連した統計リンクコスト情報を使って、当該計算開始リンクから目的地等までの複数本の経路を、簡単に算出することができる。ユーザは、これらの複数本の経路の中からいずれかを任意に選択して旅行をすることができる。
【００６３】
請求項２又は請求項１０記載の発明によれば、外部からの最新のリンクコスト情報を取得し、統計リンクコスト情報又は最新のリンクコスト情報に基づいて、現状の交通状況に基づいた複数本の経路を得ることができる。
請求項３記載の発明によれば、できるだけ差のある複数の経路を得ることができる。
【００６４】
請求項４記載の発明によれば、過去の実績に基づいた、信頼度の高い旅行時間を提供することができる。
請求項５又は６記載の発明によれば、外部からの最新のリンクコスト情報等に基づいた、実際の交通状況を反映した旅行時間を提供することができる。
請求項７又は８記載の発明によれば、通常よりも多めに見積もった最大旅行時間を表示することにより、ユーザに、最大これ位の時間がかかることを示すことができる。
【図面の簡単な説明】
【図１】本発明の経路算出装置を使用した車載ナビゲーション装置に交通情報を提供するシステムの概略図である。
【図２】車両に搭載される車載ナビゲーション装置の電気的構成を示すブロック図である。
【図３】外部から得られたリンクＬ_KaとリンクＬ_Naとの対応関係を示す図であり、図３(a) は、外部から得られたリンクＬ_KaとリンクＬ_Naとが１対１に対応する場合、図３(b) は、１つの外部から得られたリンクＬ_Kbに複数のリンクＬ_Nb1 ，Ｌ_Nb2 ，・・・，Ｌ_Nbi が含まれている場合、図３(c) は、外部から得られたリンクＬ_K にうまく対応しないリンクＬ_N が存在する場合を示す。
【図４】外部から得られたリンクと前記リンクとの対応関係を表す対応テーブルを示す図である。
【図５】車載ナビゲーション装置における複数経路の算出処理を説明するためのフローチャートである。
【図６】車載ナビゲーション装置における複数経路の算出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】車載ナビゲーション装置における複数経路の算出処理を説明するためのフローチャートである（図６の続き）。
【図８】車載ナビゲーション装置における複数経路の算出処理を説明するためのフローチャートである（図７の続き）。
【符号の説明】
Ａ 路上ビーコン
Ｂ 通信回線
Ｃ 情報センター
Ｄ 車載地図専用ディスク
１ 車載ナビゲーション装置
２ ＣＤドライブ
３ ディスプレイ
４ リモコンキー
５ 方位センサ
６ 距離センサ
７ ビーコン受信機
１１ メモリ制御部
１２ 表示制御部
１３ 入力処理部
１４ 車両位置検出部
１６ コントローラ
１６１ ＣＰＵ
１６２ ＳＲＡＭ
１６３ ＤＲＡＭ
１８ 音声制御部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a route calculation apparatus and method for calculating a plurality of routes from any link constituting route network data in a route providing area to any other link in the area.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an in-vehicle navigation device that has been developed to display the position and orientation of a vehicle on a screen and facilitate the traveling of the vehicle has been widely used. The vehicle-mounted navigation device includes a display, various sensors or a GPS receiver (hereinafter referred to as “various sensors, etc.”), a road map memory, a computer, and the like mounted on the vehicle. The vehicle position is detected based on the relationship with the stored road, and this vehicle position is displayed on the display together with the road map.
[0003]
By the way, in such an in-vehicle navigation device, not only the display of the vehicle position and the road map but also various traffic information can be provided to the driver or the passenger (hereinafter collectively referred to as “user”). A more comfortable driving environment can be provided to the user.
Therefore, in order to provide traffic information to the vehicle-mounted navigation device, traffic information can be provided to the vehicle-mounted navigation device mounted on the vehicle through road beacons and communication lines (car phone lines, etc.) installed at various places on the road. Has been done. When the in-vehicle navigation device receives the traffic information, the in-vehicle navigation device displays the traffic information on a display screen or outputs a voice. Thereby, the latest traffic information can be provided to the user.
[0004]
On the other hand, in order to select the travel route from the departure point to the destination, the computer automatically calculates the route from the current location of the vehicle (considered as the departure point) to the destination according to the user's destination setting input. Has been proposed (see Japanese Patent Laid-Open No. 5-53504). In this method, the road or lane to be calculated is represented as a series of vectors (this vector is called “link”), the link close to the departure point (or destination) may be used as the calculation start link, and the destination (even at the departure point). The link close to (good) is set as the calculation end link, the road map data stored in the road map memory between them is read and moved to the work area, and all the tree of links starting from the calculation start link are searched in the work area. In this method, a link cost tree is obtained, and the link costs of the paths constituting the tree are sequentially connected to select a path that reaches the calculation end link.
[0005]
The link cost of each link varies from moment to moment depending on traffic congestion on the road, traffic restrictions due to road construction, and the presence or absence of accidents, so road beacons and communication lines (car phone lines, etc.) ) To provide the latest link cost information to the vehicle is currently under consideration. According to this ground system, the latest link cost information including road congestion, traffic restrictions, and accident information is prepared on the ground system side, and the link cost information is transmitted to the vehicle through a road beacon or a car phone. As a result, it is possible to assist the vehicle in calculating the optimum route and calculating the travel time.
[0006]
[Problems to be solved by the invention]
However, when the in-vehicle navigation devices of a plurality of vehicles each calculate the optimum route, the link cost information acquired through the road beacon and the link cost possessed by each vehicle are the same because there is no significant difference between devices. It is expected that a plurality of vehicles going in the direction will calculate the same route, and only a specific route will be crowded and the destination cannot be reached in the shortest time.
[0007]
Therefore, in the in-vehicle navigation device, it is desirable to calculate a plurality of routes with as much difference as possible to reach the same destination, and to indicate and select the plurality of routes to the user.
To solve this problem, calculate the shortest cost between an arbitrary point and end point on the network, and calculate the partial route from the start point based on the sum of the accumulated cost from the start point and the shortest cost of the remaining routes. A method of developing a plurality of routes according to analysis conditions has been proposed (see Japanese Patent Application Laid-Open No. 5-46590). According to this proposal, it is possible to eliminate a route that greatly detours, but it is difficult to obtain a plurality of routes that are as different as possible only by obtaining a large number of routes that are almost the same as the shortest route.
[0008]
An object of the present invention is to provide a route calculation apparatus and method that can easily calculate a plurality of routes.
Another object of the present invention is to provide a route calculation apparatus and method capable of easily calculating a plurality of routes having differences as much as possible.
[0009]
[Means for Solving the Problems]
The route calculation device of the present invention is a statistical link obtained by statistically processing a road map memory storing road map data and past traffic information associated with each link for each predetermined time element. When the traffic information memory storing the cost information, the usage table in which a plurality of time zones are specified for each link constituting the road map data, and the calculation start link are specified, A plurality of designated time zones are acquired, and statistical link cost information related to each acquired time zone or a time zone after each acquired time zone is referred to from the stored contents of the traffic information memory, and these statistics are obtained. Route calculation means for calculating a plurality of routes from the calculation start link to the destination set by the user based on the link cost information; Those having a one or output means for outputting all of the calculated route by the route calculating means (claim 1).
[0010]
According to this invention, first, a plurality of time zones are recorded in the usage table for each link constituting the road map data.
When the calculation start link is determined, a plurality of time zones specified in the usage table are acquired, and statistical link cost information related to each acquired time zone is referred to from the storage contents of the traffic information memory, and the calculation starts. A plurality of routes from the link to the destination set by the user can be calculated.
[0011]
The plurality of time zones recorded in the usage table may be, for example, a time zone in which a plurality of time zones are selected and recorded at random or with a certain promise from the time zones divided in the day. This time zone should be scattered as much as possible without being biased throughout the day. Multiple time zones corresponding to a single link may be different for different seasons, months, days of the week, and weekdays / holidays, and are the same for different seasons, months, days of the week, and weekdays / holidays. It may be a time zone.
[0012]
The route calculation device of the present invention includes a road map memory in which road map data is stored, communication means for acquiring the latest link cost information from the outside, the latest link cost information acquired by the communication means, and each link. A traffic information memory storing statistical link cost information obtained by statistically processing past traffic information associated with each predetermined time element, and a plurality of links for each link constituting road map data When a usage table with a specified time zone and a calculation start link are specified, a plurality of time zones specified in the usage table are acquired for the calculation start link, and each acquired time zone or each acquired time zone is acquired. Refer to statistical link cost information or latest link cost information related to the time zone after the time zone from the storage contents of the traffic information memory, respectively. Based on the statistical link cost information or the latest link cost information, the route calculation means for calculating a plurality of routes from the calculation start link to the destination set by the user, and the route calculation means Output means for outputting any or all of the routes (claim 2).
[0013]
According to the present invention, when calculating a route, a plurality of routes can be provided by using travel time based on the latest link cost information from the outside.
The route calculation device according to the present invention is the route calculation device according to claim 1 or 2, wherein a plurality of routes are calculated by the route calculation means. % Difference Check % Variance is greater than threshold Only the route is selected, and the selected route is the display target (claim 3).
[0014]
This is because if a plurality of routes provided to the user are similar routes, it is meaningless to provide a plurality of routes.
The route calculation apparatus according to the present invention is the route calculation device according to claim 1, wherein the travel time calculation calculates the route travel time by referring to the statistical link cost information along the route calculated by the route calculation means. Means for outputting route travel time (claim 4).
[0015]
When the travel time is provided to the user together with the route, the travel time based on the statistical link cost information can be provided, so that the travel time with high reliability based on the past performance can be provided.
The route calculation device according to the present invention is the route calculation device according to claim 1, wherein the statistical link cost along the route calculated by the communication means for obtaining the latest link cost information from the outside and the route calculation means. It further includes a travel time calculating means for calculating a route travel time by referring to the information and the latest link cost information obtained through the communication means, and the output means also outputs the route travel time ( Claim 5).
[0016]
When the travel time is provided to the user along with the route, the travel time based on the latest link cost information from the outside can be provided, so that the travel time taking into account the current situation can be provided.
The route calculation device according to the present invention is the route calculation device according to claim 2, wherein the route calculation device refers to the statistical link cost information and the latest link cost information along the route calculated by the route calculation means. Travel time calculation means for calculating travel time is further provided, and the output means outputs route travel time.
[0017]
When the travel time is provided to the user along with the route, the travel time based on the latest link cost information from the outside can be provided, so that the travel time taking into account the current situation can be provided.
The route calculation device according to the present invention is the route calculation device according to claim 4, wherein the route maximum travel is obtained by multiplying the route travel time calculated by the travel time calculation means by a fixed number (1 + b) (b is a positive real number). It further has route maximum travel time calculation means for calculating time, and the output means also outputs the route maximum travel time.
[0018]
The route calculation device according to the present invention is the route calculation device according to claim 5 or 6, wherein the route travel time calculated by the travel time calculation means is multiplied by a fixed number (1 + a) (a is a positive real number). It further has route maximum travel time calculation means for calculating the maximum travel time, and the output means outputs the route maximum travel time.
According to these inventions, by displaying the maximum travel time estimated more than usual, it is possible to indicate to the user that the maximum time is required.
[0019]
The route calculation method of the present invention is a route calculation method according to the same invention as the route calculation device according to claim 1 or claim 2 (claims 9 and 10).
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of a system for providing traffic information to an in-vehicle navigation device to which the route calculation device of the present invention is applied. This traffic information providing system includes a road beacon A installed on each road in a traffic information providing area and an information center C connected to the road beacon A via a communication line (public line or dedicated line) B. Is included.
[0021]
The road beacon A may be either a radio wave beacon or an optical beacon. Instead of the road beacon A, for example, a communication device or a transmission device used in an automobile / mobile phone network or FM multiplex broadcasting network is applied. Also good.
In the information center C, link traffic information corresponding to a relatively coarse first route network having a link connecting main intersections in the traffic information provision area as a constituent unit is stored. This link traffic information is associated with each link, for example, the latest traffic information that changes from moment to moment acquired by a vehicle detector, a camera, a helicopter that travels over the sky, or a traffic information collection vehicle that actually travels on the road. It was created.
[0022]
The link traffic information includes, for example, contents corresponding to a travel time, a traffic congestion degree, or a traffic jam length that is a time required for a vehicle to travel on a road corresponding to a link. For example, when a traffic jam occurs, the travel time or the traffic jam length is relatively long and the traffic jam degree is relatively large.When the traffic jam is resolved, the travel time or the traffic jam length is relatively short and the traffic jam degree is a relative traffic jam. Is made smaller. In addition, when an accident or the like occurs and the traffic becomes impossible, the travel time is infinite. The same applies to traffic restrictions. This link traffic information is given to the road beacon A via the communication line B every predetermined time (for example, 5 minutes). Each of the divided fixed times is called a “time zone”. For example, if it is divided every 5 minutes, there are 288 time zones per day.
[0023]
When the link traffic information is given through the communication line B, the road beacon A transmits the link traffic information to the vehicle.
FIG. 2 is a block diagram showing an electrical configuration of the in-vehicle navigation device mounted on the vehicle. The in-vehicle navigation device 1 includes an azimuth sensor 5 that detects the amount of azimuth change of the vehicle and a distance sensor 6 that detects the amount of movement of the vehicle. As the azimuth sensor 5, for example, a gyro such as an optical fiber gyro, a vibration gyro, a gas rate gyro, or a geomagnetic sensor is applicable. Further, as the distance sensor 6, for example, a rotation speed sensor that detects the rotation speed of a tire wheel or a rotor can be applied. The outputs of the azimuth sensor 5 and the distance sensor 6 are given to the vehicle position detection unit 14 in the in-vehicle navigation device body 1.
[0024]
In the vehicle position detection unit 14, the traveling direction of the vehicle is obtained based on the output of the direction sensor 5, and the travel distance of the vehicle is obtained based on the output of the distance sensor 6. The vehicle position detector 14 is provided with accurate initial position data of the vehicle by the user before the vehicle starts, and the vehicle position detector 14 receives the initial position data given in advance and the vehicle's position. The current location of the vehicle is detected based on the accumulation of the traveling direction and the traveling distance. The detection of the current location of the vehicle is repeated at regular intervals (for example, 1 second).
[0025]
A GPS (Global Posioning System) satellite that navigates the orbit of the earth instead of the azimuth sensor 5, the distance sensor 6, and the vehicle position detector 14, or together with the azimuth sensor 5, the distance sensor 6, and the vehicle position detector 14. You may employ | adopt the GPS receiver which detects the present location of a vehicle based on the propagation delay time of the GPS electromagnetic wave transmitted from.
[0026]
The vehicle position detection unit 14 also corrects the detected current position of the vehicle by a so-called map matching process (see, for example, Japanese Patent Laid-Open No. 63-148115). That is, the degree of similarity between the travel locus of the vehicle detected based on the outputs of the azimuth sensor 5 and the distance sensor 6 and the road stored in the in-vehicle map dedicated disk D is collated, and according to the result. The travel locus of the vehicle is corrected on the road.
[0027]
The current position data of the vehicle corrected by the map matching process is given to the controller 16.
The controller 16 is a control center of the in-vehicle navigation device body 1 and includes a CPU 161, an SRAM 162, and a DRAM 163. When the current position data of the vehicle is given from the vehicle position detector 14, the controller 16 reads the road map data for display from the in-vehicle map dedicated disk D via the memory controller 11 and the CD drive 2. The read display road map data and the current location data are provided to the display control unit 12. When the display road map data and the current location data are given, the display control unit 12 superimposes a car mark representing the current location of the vehicle on the road map on the display 3 constituted by a liquid crystal display element, a plasma display element or a CRT. Display. Also, guidance information along the route is provided by voice through the speaker M.
[0028]
In addition to the display road map data, route map road map data, a correspondence table, and a usage table are stored in the vehicle-mounted map dedicated disk D.
The road map data for route calculation is obtained by dividing the road map (including highway automobile national roads, automobile exclusive roads, other national roads, prefectural roads, city roads of government-designated cities, and other living roads) into meshes. A relatively fine second route network composed of a combination of nodes corresponding to road intersections and the like, and links that are vectors that connect each node, is a highway / national road map, a general road map, and a detailed map. Are divided into three layers and stored for each time zone. The stored contents are fixed link cost, statistical link cost T for each time zone. _S (t) The link length for each link, the coordinates of the start node and end node of the link, and the like are associated with each other.
[0029]
Statistical link cost T _S (t) is created in advance, and based on the link traffic information for each time zone provided in the traffic information provision area during the past certain period through the road beacon A, the season, the month, the day of the week The average value is stored for each one or a plurality of combinations of weekday / holiday etc. (these are called time elements), and the value is written in the vehicle-mounted map dedicated disk D.
[0030]
Statistical link cost T _S Describing in detail the method of creating (t), it is conceivable to collect past link traffic information using, for example, a traffic information facsimile service. In addition to this traffic information facsimile service, it is also possible to use a traffic information providing service by radio broadcasting or a traffic information providing service by cable television (CATV) which is implemented by the road traffic information center.
[0031]
The case where the traffic information facsimile service is used will be described in detail. The traffic information facsimile service provides traffic information such as traffic jam information, travel time, and traffic prohibition sections indicated on characters and maps by facsimile. The creator classifies the traffic information provided by the facsimile by time zone, season, month, day of the week, weekday / holiday, and organizes it statistically. For example, when traffic information is taken as an example of traffic information, the traffic information is statistically processed, and the result is organized as statistical traffic information data.
[0032]
In addition to the road map data, the map dedicated disk D stores a correspondence table representing a correspondence relationship between a link associated with traffic information transmitted from the road beacon A and a link of the road map data. (See FIG. 4).
This correspondence can be classified as follows because the link associated with the traffic information transmitted from the road beacon A is generally a constituent unit of the route network that is coarser than the link of the road map data. FIG. 3A shows the link L transmitted from the road beacon A. _Ka And road map data link L _Na And correspond to one-to-one. FIG. 3 (b) shows one link L transmitted from the road beacon A. _Kb Link L for multiple road map data _Nb1 , L _Nb2 , ..., L _Nbi 3 (c) shows the link L transmitted from the road beacon A. _K Link L of road map data that does not correspond well to _N Indicates the presence of. Among these, the correspondence table represents the correspondence in the cases of FIGS. 3A and 3B, and FIG. 4 shows specific examples of the correspondence table. In the case of FIG. 3C, since there is no direct correspondence relationship, description of the correspondence table is omitted in this embodiment.
[0033]
The usage table is associated with the link of the road map data, and the effective time zone Z _k The number is recorded.
[0034]
[Table 1]

[0035]
Effective time zone Z _k Is selected from a plurality of “time zones” divided into a large number per day, and this effective time zone Z is used as the link cost of the calculation start link. _k Statistical link cost T _S Adopt (t) and perform route search for the links connected to it.
For example, for the 251st link, the time zones of numbers 2, 9, 14, 32, etc. are recorded. Therefore, in the route search, the statistical link cost T of the calculation start link _S (t) as the statistical link cost T in the time zone number 2 _S (t) is adopted, a route search is performed for a link connected thereto, and the statistical link cost T in the time zone of number 9 is determined. _S (t) is adopted, a route search is performed for the link connected thereto, and the statistical link cost T in the time zone of number 14 is determined. _S Adopt (t), perform a route search for the links connected to it, and so on.
[0036]
A remote controller key (hereinafter simply referred to as “remote control key”) 4 for inputting a destination and various calculation conditions is connected to the controller 16 via an input control unit 13. The remote control key 4 includes, for example, a “joystick / set key” for scrolling a map, setting a position, and selecting a menu, a “map key” for displaying a road map screen centering on a car mark representing the current location, a road map “Scale key” to enlarge / reduce the display scale, “Rotation key” to select whether to display the traveling direction of the vehicle up or north of the map, and whether to display the vehicle's travel locus Menu screens such as “route key”, “route key”, “destination setting”, “route setting”, etc. that can input the route calculation instruction signal with one touch when you want to calculate the shortest time route from the current location to the destination Various keys (not shown) such as a “menu key” to be displayed and a “return key” to return to the previous screen when the menu is operated are provided.
[0037]
The controller 16 allows the user to specify the destination and various calculation conditions (whether priority is given to toll roads, priority to ferry use, whether to go through a transit point, etc.) via the remote control key 4. When inputted, the inputted destination data and the like are stored in the SRAM 162, and the road map data for route calculation is read out from the on-vehicle map dedicated disk D, and the destination and the current location detected by the vehicle position detecting unit 14 are respectively read. The shortest time path between close links is calculated using, for example, the Dijkstra method or the potential method. The calculated shortest time route is superimposed and displayed on the road map displayed on the display 3 with, for example, a broken line.
[0038]
Here, the potential method is the following method. That is, the link near the departure point (or destination) may be the calculation start link, the link closest to the destination (or departure point) may be the calculation end link, and calculated based on various calculation conditions entered by the user. All links within a predetermined map area starting from the start link are searched. At this time, the statistical link cost T of each link _S (t) or estimated travel time T _P (t) Repeat the process of sequentially adding (to be described later), discarding the non-shortest route, and leaving only the route that realizes the shortest route. As a result, a tree of routes consisting only of the shortest route is finally obtained. Therefore, if the route from the calculation end link to the calculation start link is traced in reverse, the shortest time route can be obtained.
[0039]
A beacon receiver 7 is also connected to the controller 16. When the vehicle enters the transmission area of the road beacon A (see FIG. 1) and a series of the latest link traffic information transmitted from the road beacon A is received by the beacon receiver 7, the CPU 161 Traffic information is given to the SRAM 162 and held. When the CPU 161 calculates the shortest time route by the above method, if the link traffic information is held in the SRAM 162, the statistical link cost T included in the route map road map data is stored. _S The predicted link cost T is calculated by adding the link cost obtained by using the link traffic information (hereinafter referred to as “real-time link cost”) to (t) _P (t) is obtained, and the predicted link cost T _P Multiple routes are calculated based on (t). If link traffic information is not stored in the SRAM 162, the statistical link cost T _S A plurality of routes are calculated using (t) as they are.
[0040]
FIGS. 5 to 8 are flowcharts for explaining a calculation process of a plurality of routes in the in-vehicle navigation device 1.
The user operates the remote controller key 4 to input a destination or waypoint (hereinafter, representatively referred to as “destination”) before or during traveling. The controller 16 sets the link closest to the current location detected by the vehicle position detection unit 14 as the calculation start link and the link closest to the destination as the calculation end link (step S1 in FIG. 5).
[0041]
Next, referring to the current time, the departure time zone Z to which the current time belongs ₀ Is specified (step S2). Then, referring to the usage table described above, the departure time zone Z to which the current time belongs, corresponding to the calculation start link ₀ The subsequent time zones are checked in order (step S3), and the hit time zone, that is, the valid time zone Z _k Are specified (step S4).
[0042]
Then, the controller 16 searches for all the links in the predetermined map area starting from the calculation start link.
In this search, first, the statistical link cost T _S A method for calculating a plurality of routes using (t) as it is will be described. After that, link traffic information is stored in the SRAM 162, and prediction is performed by taking into consideration the real-time link cost of the link obtained using the link traffic information. Link cost T _P (t) is obtained, and the predicted link cost T _P A method for calculating a plurality of routes based on (t) will be described.
<Statistical link cost T _S Method of calculating multiple routes using (t) as is>
In this method, as the link cost of a link in a predetermined map area, a statistical link cost T belonging to a different time zone for each link. _S Use (t).
[0043]
Explaining in detail, effective time zone Z _k Of these, the earliest valid time zone Z ₁ Is selected first, and the link cost of the calculation start link is set to the effective time zone Z ₁ Statistical link cost T _S (t).
Next, for the link following this calculation start link, the effective time zone Z of the calculation start link ₁ The effective time zone later than the calculation start link by the link cost, that is, the time zone in which the vehicle is considered to reach the link is determined, and the statistical link cost T belonging to the effective time zone is determined. _S (t) is used as the link cost.
[0044]
Similarly, the link cost is added to the link leading to this, and the statistical link cost T in the time zone in which the vehicle is expected to reach the link is added. _S A route is searched using (t) as the link cost (step S5).
It should be noted that the statistical link cost T of the time zone in which the vehicle is expected to reach the link _S Instead of using (t) as the link cost, the effective time zone Z of the calculation start link is uniformly applied to all links in the predetermined map area. ₁ Same time zone Z ₁ Statistical link cost T _S (t) may be used as the link cost.
<Real-time link cost and statistical link cost T _S Method of calculating multiple routes using (t) together>
If the route is obtained by using the real-time link cost as it is, the instantaneous fluctuation of the real-time link cost is too severe. In this method, the statistical link cost T _S Predicted link cost T using exponential smoothing method with (t) added _P (t) is obtained, and the predicted link cost T _P The route in the predetermined map area is searched using (t) as the link cost.
[0045]
In this exponential smoothing method, when the link for the route calculation and the link obtained from the outside have a one-to-one correspondence as shown in FIG. 3A, the statistics corresponding to the link obtained from the outside are used. Link cost T _S (t) is read from the SRAM 162 and the statistical link cost T _S Estimated error e required to correct (t) _t Ask for.
The error prediction value e _t The initial value is set to 0, but since the instantaneous fluctuation of the real-time link cost is too intense, the predicted link cost T _P It is necessary to absorb the instantaneous fluctuation of (t). For this reason, the error prediction value e adopted based on the real-time link cost of the same externally obtained link _t-1 The error prediction value e by taking a weighted average in consideration of _t And
[0046]
More specifically, the predicted link cost T _P When (t) is obtained, the predicted link cost T _P (t) and the statistical link cost T of the link obtained from the outside _S Find the difference from (t).
Next, the predicted link cost T of the previous time of the same link held in the memory _P (t−1) is read, and the statistical link cost T of this link _S Taking the difference from (t), the error prediction value e _t-1 And the new error prediction value e as shown in the following equation (1) _t Update to
[0047]
e _t = Α (T _P (t) -T _S (t)) + (1-α) e _t-1 (1)
In the equation (1), α (0 <α <1) is a smoothing index, and if it is close to 0, the past error prediction value e _t-1 If the weight is close to 1, the current predicted link cost T _P (t) is weighted. For example, α = 0.8.
The error prediction value e obtained in this way _t Is used to predict the predicted link cost T corresponding to the route calculation target link as shown in the following equation (2): _P Calculate (t).
[0048]
T _P (t) = e _t + T _S (t) (2)
In the above description, the focus is on the difference between the predicted link cost and the statistical link cost. However, the ratio between the predicted link cost and the statistical link cost may be focused. In this case, the equations (3) and (4) are as follows (e _t The initial value is 1).
[0049]
e _t = Α (T _P (t) / T _S (t)) + (1-α) e _t-1 (3)
T _P (t) = e _t ・ T _S (t) (4)
Further, as shown in FIG. 3 (b), when the link is included as a part of the link obtained from the outside, the predicted link cost T based on the equation (2) or (4) _P After (t) is calculated, the following equation (5) is calculated, and the predicted link cost T corresponding to the relevant route calculation target link is calculated. _P (t) is calculated. However, in the following equation (5), d _Ni Is the link _i Link length of d _K Represents the link length of the link obtained from the outside.
[0050]
(D _Ni / D _K ) × T _P (t) → T _P (t) (5)
Predicted link cost T calculated by equation (2) or (4) or (5) _P (t) is held in non-volatile memory.
Thus, the error prediction value e _t Is obtained in order to absorb instantaneous fluctuations in the real-time link cost. _t Predicted link cost T obtained using _P (t) is a value that reflects current traffic conditions and suppresses extreme fluctuations in actual traffic conditions. Therefore, this predicted link cost T _P The route in the predetermined map area is searched using (t) (step S5).
[0051]
When the search for the route is completed, the route from the calculation end link to the calculation start link is traced in reverse. ₁ Is identified and stored (step S6).
Furthermore, the effective time zone Z that hits the usage table _k Of these, the next effective time zone Z ₂ And select <statistical link cost T _S Method of calculating a plurality of routes using (t) as they are> or <Real-time link cost and statistical link cost T _S (t) is used together to calculate a plurality of routes> ₂ Is identified and memorized. By repeating this, the effective time zone Z _n Multiple routes L corresponding to (n = 1,2,3, ..., m) _n Specify (n = 1,2,3, ..., m). All valid time zones Z _k When the check is completed, the process proceeds from step S7 to step S11 (FIG. 6), and a plurality of stored routes L _n (n = 1,2,3,..., m) are taken out in order and the difference rate D is checked.
[0052]
This difference rate D means that each route L _n Any two paths L from (n = 1,2,3, ..., m) _i , L _j And link cost for them (eg statistical link cost T _S (t) Route travel time T _i , T _j And further the route L _i , L _j Route travel time T _ij And using these,
D _ij = 1-2T _ij / (T _i + T _j )
It is a function represented by This percentage difference D _ij Is compared with a threshold value (step S12), and the difference rate D _ij Is smaller than the threshold value (step S13), the route with the longer route travel time is deleted, the process returns to step S11, and the process is repeated for the other routes. In this way, the difference rate D _ij Only routes with a value greater than the threshold are selected (step S14). All stored routes L _n When the processing is completed for (n = 1, 2, 3,..., m) (step S15), the process proceeds to step S21 (FIG. 7).
[0053]
In the above explanation, the difference rate D is the route travel time T _i , T _j , T _ij However, it may be based on the route distance. Also, instead of calculating the difference rate D, the absolute difference (T _i + T _j ) / 2-T _ij May be calculated and compared to a threshold value.
After step S21, each selected route (this is designated as route L). _p Link travel time is calculated for the links that make up In calculating the link travel time, the link travel time is determined by determining the time when the vehicle is expected to reach the link. Add cost (this idea is the same as when searching for a route).
[0054]
First, processing is sequentially performed for one route from the calculation start link (step S22).
For the link, the predicted link cost T _P It is checked whether (t) is obtained (step S23).
If not, statistical link cost T _S By adopting (t), this is set as the normal travel time (step S24). Further, (1 + b) is multiplied by the normal travel time, and this is set as the maximum travel time (step S25). The maximum travel time is calculated to indicate to the user that it will take more time than usual to estimate. b is the statistical link cost T _S The higher the reliability of (t), the smaller the statistical link cost T _S (t) Increase the lower the reliability. Usually, b = about 0.1 to 0.2.
[0055]
For the link, the predicted link cost T _P If (t) is obtained, the predicted link cost T _P By adopting (t), this is set as the normal travel time (step S26). Further, (1 + a) is multiplied by the normal travel time, and this is set as the maximum travel time (step S27). a is the predicted link cost T _P The smaller the reliability of (t), the smaller the predicted link cost T _P (t) Increase the lower the reliability. Usually, a = 0.1 to about 0.2.
[0056]
One route L _P If the processing is completed for all the links that constitute (step S28), the process proceeds to step S31 (FIG. 8).
In step S31, the route L _p The total travel time is totaled, and this is used as the route travel time (step S31). Further, the maximum travel time is totaled, and this is set as the route maximum travel time (step S32).
[0057]
The predicted link cost T described above _P In addition to the method of calculating travel time based on (t), the predicted link cost T _P (t) is ignored and statistical link cost T _S Travel time can also be calculated based only on (t).
Other route L _p Is also processed in step S21 and subsequent steps, all routes L _p If the processing is finished for (step S33), the obtained route L _P It is determined whether or not the number exceeds a certain number c (step S34). If a certain number c is exceeded, c routes (the routes L _Q Is finally selected (step S36). If the predetermined number c is not exceeded, the entire route L _P Route L _Q As a final selection (step S35).
[0058]
And finally selected route L _Q Is displayed (step S37). This display shows the last selected route L _Q May be displayed all at once, or any one route L _Q If there is a user request, another route L is displayed. _Q You may make it switch to.
The route travel time and the maximum route travel time are also displayed (step S38). When this display is performed, it is needless to say that it is desirable to change the display method depending on whether it is a simple route travel time or a maximum route travel time.
[0059]
Then, guidance instruction information corresponding to the route is created. As the contents of the guidance instruction information corresponding to this route, there are various conventionally known information such as the direction to the destination, the straight line distance to the destination, the route distance along the route, the intersection schematic diagram, etc. Any or all of these information is provided to the user. In the providing method, characters or arrows may be displayed on the display 3 or may be guided by voice from the speaker M.
[0060]
The description of the embodiments of the present invention is as described above, but the present invention is not limited to the above-described embodiments. For example, in the above-described embodiment, the calculation of a plurality of routes is performed by the in-vehicle navigation device. However, a plurality of routes may be calculated by a ground system such as the information center C and provided to each vehicle through the road beacon A, or the user may use a personal computer installed in an office or the like. Multiple routes may be calculated.
[0061]
In addition, various design changes can be made within the scope of the present invention.
[0062]
【The invention's effect】
As described above, according to the first or ninth aspect of the invention, the usage table is used to acquire a plurality of time zones specified in the usage table, and the statistical link costs associated with the acquired time zones, respectively. Using the information, it is possible to easily calculate a plurality of routes from the calculation start link to the destination. The user can travel by arbitrarily selecting any one of the plurality of routes.
[0063]
According to the invention of claim 2 or claim 10, the latest link cost information from the outside is acquired, and a plurality of links based on the current traffic situation are obtained based on the statistical link cost information or the latest link cost information. A route can be obtained.
According to the third aspect of the present invention, it is possible to obtain a plurality of routes that are as different as possible.
[0064]
According to the invention described in claim 4, it is possible to provide a highly reliable travel time based on the past performance.
According to invention of Claim 5 or 6, the travel time reflecting the actual traffic condition based on the latest link cost information etc. from the outside can be provided.
According to the seventh or eighth aspect of the invention, by displaying the maximum travel time estimated more than usual, it can be shown to the user that this time is maximum.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a system for providing traffic information to an in-vehicle navigation device using a route calculation device of the present invention.
FIG. 2 is a block diagram showing an electrical configuration of an in-vehicle navigation device mounted on a vehicle.
Fig. 3 Link L obtained from the outside _Ka And link L _Na FIG. 3A shows a link L obtained from the outside. _Ka And link L _Na FIG. 3 (b) shows a link L obtained from one outside. _Kb Multiple links L _Nb1 , L _Nb2 , ..., L _Nbi 3 (c) shows the link L obtained from the outside. _K L that does not respond well to _N Indicates the presence of.
FIG. 4 is a diagram showing a correspondence table representing a correspondence relationship between a link obtained from the outside and the link.
FIG. 5 is a flowchart for explaining a calculation process of a plurality of routes in the in-vehicle navigation device.
FIG. 6 is a flowchart for explaining a calculation process of a plurality of routes in the in-vehicle navigation device (continuation of FIG. 5).
FIG. 7 is a flowchart for explaining a calculation process of a plurality of routes in the in-vehicle navigation device (continuation of FIG. 6).
FIG. 8 is a flowchart for explaining calculation processing of a plurality of routes in the in-vehicle navigation device (continuation of FIG. 7).
[Explanation of symbols]
A street beacon
B Communication line
C Information Center
D Car map dedicated disc
1 Car navigation system
2 CD drive
3 Display
4 Remote control keys
5 Direction sensor
6 Distance sensor
7 Beacon receiver
11 Memory controller
12 Display controller
13 Input processing section
14 Vehicle position detector
16 controller
161 CPU
162 SRAM
163 DRAM
18 Voice control unit

Claims (10)

A road map memory storing road map data;
A traffic information memory storing statistical link cost information obtained by statistically processing past traffic information associated with each link for each predetermined time element;
A usage table in which multiple time zones are specified for each link constituting the road map data,
When the calculation start link is specified, a plurality of time zones specified in this usage table are acquired for the calculation start link, and the statistical links related to the acquired time zones or the time zones after the acquired time zones, respectively. Route calculation means for referencing cost information from the stored contents of the traffic information memory, and calculating a plurality of routes from the calculation start link to a destination set by the user based on the statistical link cost information; ,
A route calculation apparatus comprising: output means for outputting any or all of the routes calculated by the route calculation means. A road map memory storing road map data;
A communication means for obtaining the latest link cost information from the outside;
Traffic information storing statistical link cost information obtained by statistically processing the latest link cost information acquired by communication means and past traffic information associated with each link for each predetermined time element Memory,
A usage table in which multiple time zones are specified for each link constituting the road map data,
When the calculation start link is specified, a plurality of time zones specified in this usage table are acquired for the calculation start link, and the statistical links related to the acquired time zones or the time zones after the acquired time zones, respectively. The cost information or the latest link cost information is referred to from the storage contents of the traffic information memory, and from the calculation start link to the destination set by the user based on the statistical link cost information or the latest link cost information. A route calculation means for calculating a plurality of routes,
A route calculation apparatus comprising: output means for outputting any or all of the routes calculated by the route calculation means. When a plurality of routes are calculated by the route calculation unit, the route calculation unit further includes a selection unit that checks a route difference rate and selects only a route having a difference rate larger than a threshold value , and the output unit selects the selection unit The route calculation apparatus according to claim 1, wherein the route is output. A travel time calculating means for calculating a route travel time with reference to the statistical link cost information along the route calculated by the route calculating means,
The route calculation apparatus according to claim 1, wherein the output means outputs a route travel time. A communication means for obtaining the latest link cost information from the outside;
Travel time calculation means for calculating the route travel time with reference to the statistical link cost information and the latest link cost information obtained through the communication means along the route calculated by the route calculation means;
The route calculation apparatus according to claim 1, wherein the output means outputs a route travel time. A travel time calculation means for calculating a route travel time with reference to the statistical link cost information and the latest link cost information along the route calculated by the route calculation means,
3. The route calculation apparatus according to claim 2, wherein the output means also outputs route travel time. A route maximum travel time calculating means for calculating a route maximum travel time by multiplying the route travel time calculated by the travel time calculating means by a fixed number (1 + b) (b is a positive real number);
5. The route calculation apparatus according to claim 4, wherein the output means outputs a maximum route travel time. A route maximum travel time calculating unit that calculates a route maximum travel time by multiplying the route travel time calculated by the travel time calculating unit by a fixed number (1 + a) (a is a positive real number);
The route calculation apparatus according to claim 5 or 6, wherein the output means outputs a route maximum travel time. A road map memory storing road map data;
For each link constituting the road map data, a traffic information memory storing statistical link cost information obtained by statistically processing past traffic information associated with each link for each predetermined time element, Using a usage table with multiple time zones specified,
Identify the calculation start link,
Obtain multiple time zones specified in this usage table for the calculation start link,
Refer to statistical link cost information related to each acquired time zone or a time zone after each acquired time zone from the storage contents of the traffic information memory, respectively.
A route calculation method comprising: calculating a plurality of routes from the calculation start link to a destination set by a user based on the statistical link cost information. A road map memory storing road map data;
A communication means for obtaining the latest link cost information from the outside;
Traffic information storing statistical link cost information obtained by statistically processing the latest link cost information acquired by communication means and past traffic information associated with each link for each predetermined time element Memory,
Using a usage table with multiple time zones specified for each link that makes up the road map data,
Identify the calculation start link,
Obtain multiple time zones specified in this usage table for the calculation start link,
Refers to the statistical link cost information or the latest link cost information related to each acquired time zone or the time zone after each acquired time zone from the stored contents of the traffic information memory, respectively.
A route calculation method comprising: calculating a plurality of routes from the calculation start link to a destination set by a user based on the statistical link cost information or the latest link cost information.

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