JP3668503B2 - Road shape determination device - Google Patents

Description

が成立し、これから cosθ₁ が求められる。
【００３２】
また、ベクトルＶ₁₂とベクトルＶ₂₄との成す角度をθ₂ とすると、ベクトルＶ₁₂及びベクトルＶ₂₄の内積から、

が成立し、これから cosθ₂ が求められる。
【００３３】
次に、変化率αを
α＝（ cosθ₁ − cosθ₂ ）／ cosθ₁ …▲３▼
により演算する。
【００３４】
式▲３▼から明らかなように、変化率αの絶対値が小さい場合は、θ₁ 及びθ₂ が略一致していて道路の曲がりが小さい場合（即ち、直線路）に対応しており、逆に変化率αの絶対値が大きい場合は、θ₁ 及びθ₂ が大きく異なっていて道路の曲がりが大きい場合（即ち、クランク路や急カーブ）に対応している。
【００３５】
尚、道路の曲がり方向はベクトルＶ₁₂及びベクトルＶ₂₃の外積、即ちＸ₁₂・Ｙ₂₃−Ｙ₁₂・Ｘ₂₃の正負によって判定することができる。
【００３６】
而して、図６及び図７に示すように、道路形状判定手段Ｍ５が前記変化率αの値に応じて種々の道路形状を判定する。
【００３７】
上述のようにして判定された道路形状がカーブであれば（ステップＳ４）、更にそのカーブがＳ字カーブ又はクランク路か否かを判断する（ステップＳ５）。そして、道路形状が単なるカーブであれば表示手段Ｍ７にカーブの予告を表示するとともに（ステップＳ６）、道路形状が通過し難いＳ字カーブ又はクランク路であれば表示手段Ｍ７にＳ字カーブ又はクランク路の予告を表示する（ステップＳ７）。
【００３８】
次に、判定した道路形状に対して現在の車速Ｖ₀ の適否を判断し（ステップＳ８）、現在の車速Ｖ₀ が前方のカーブを曲がり得る車速に対して過大である場合には、警報手段１２により乗員に警報が発せられる（ステップＳ９）。前記警報にも関わらずカーブを確実に曲がり得る適正車速まで減速が行われない場合には（ステップＳ１０）、車速調整手段１３により自動減速が行われる（ステップＳ１１）。そして、自車が対象となるカーブを通過するか、或いは車速Ｖ₀ が前記適正車速まで減速されると（ステップＳ１２）、自動減速が停止されるとともにステップＳ１に復帰する。
【００３９】
一方、前記ステップＳ８，Ｓ１０の答えがＮＯで自動減速が不要であれば、判定区間Ｓ₂ の全域について処理を行ったか否かを判断し（ステップＳ１３）、その答えがＮＯであって判定区間Ｓ₂ の全域について処理が終了していなければ前記ステップＳ３に復帰し、基準ノードＮ₁ 〜Ｎ₄ を前方側にずらして前述した処理を繰り返し、その結果ステップＳ１３の答えがＹＥＳになって全ての処理が終了すると前記ステップＳ１に復帰する。
【００４０】
上述したように、複数のノードＮの座標Ｎ（Ｘ，Ｙ）の集合よりなる地図情報に基づいて道路形状を判定しているので、設備費や維持費が嵩むインフラストラクチャーの整備が不要であるばかりか、ＣＤ−ＲＯＭやＩＣカードに記憶可能な最小限のデータ量で道路形状を判定することができる。
【００４１】
次に、図８〜図１５に基づいて本発明の第２実施例を説明する。図８は第１実施例の図２に対応するブロック図、図９は較差の説明図、図１０は道路形状の求め方を示す説明図、図１１は円弧カーブの曲率半径の求め方を示す説明図、図１２は道路形状のパターンを示す図、図１３は道路形状のパターンを示す図、図１４は非円弧カーブの判定法を示す説明図、図１５は道路形状の判定基準を示す図である。
【００４２】
第２実施例は相互に隣接する３個の基準ノードＮ₁ ，Ｎ₂ ，Ｎ₃ に基づいて道路形状を判定するもので、図８に示すように角度演算手段Ｍ４の出力と距離演算手段Ｍ６の出力とに基づいて道路形状を判定する点で第１実施例と異なっており、その他の構成は第１実施例と同一である。
【００４３】
尚、第２実施例の地図情報はデータ作成上の規約として、隣接するノードＮを結ぶ線分と道路との距離（以下、較差という）が所定の基準値ｋ以下になるように各ノードＮの位置が決定されている。即ち、図９に示すように、道路の曲率半径が小さい部分では、隣接するノードＮ間の距離を小さく設定することにより前記較差が基準値ｋ以下に抑えられている。
【００４４】
３個の基準ノードＮ₁ ，Ｎ₂ ，Ｎ₃ の抽出は以下のようにして行われる。即ち、最初に抽出される３個の基準ノードＮ₁ ，Ｎ₂ ，Ｎ₃ のうちの最も手前側の第１基準ノードＮ₁ が先読み区間Ｓ₁ の先端に設定され、その前方に隣接するノードＮが第２基準ノードＮ₂ とされ、更にその前方に隣接するノードＮが第３基準ノードＮ₃ とされる。これら３個の基準ノードＮ₁ ，Ｎ₂ ，Ｎ₃ は前方側にずらして順次抽出される。
【００４５】
次に、前記３個の基準ノードＮ₁ 〜Ｎ₃ の座標に基づいて道路形状を判定する手法を説明する。。
【００４６】
先ず、図１０に示すように、角度演算手段Ｍ４により第１基準ノードＮ₁ （Ｘ₁ ，Ｙ₁ ）と第２基準ノードＮ₂ （Ｘ₂ ，Ｙ₂ ）とを結ぶベクトルＶ₁₂（Ｘ₁₂，Ｙ₁₂）と、第２基準ノードＮ₂ （Ｘ₂ ，Ｙ₂ ）と第３基準ノードＮ₃ （Ｘ₃ ，Ｙ₃ ）とを結ぶベクトルＶ₂₃（Ｘ₂₃，Ｙ₂₃）との成す角度θの演算を行う。
【００４７】
即ち、ベクトルＶ₁₂及びベクトルＶ₂₃の内積から、

が成立し、これから角度θが求められる。
【００４８】
次に、距離演算手段Ｍ６により第１基準ノードＮ₁ （Ｘ₁ ，Ｙ₁ ）と第２基準ノードＮ₂ （Ｘ₂ ，Ｙ₂ ）との距離Ｌ₁₂と、第２基準ノードＮ₂ （Ｘ₂ ，Ｙ₂ ）と第３基準ノードＮ₃ （Ｘ₃ ，Ｙ₃ ）との距離Ｌ₂₃と、第１基準ノードＮ₁ （Ｘ₁ ，Ｙ₁ ）と第３基準ノードＮ₃ （Ｘ₃ ，Ｙ₃ ）との距離Ｌ₁₃とを演算する。
【００４９】
Ｌ₁₂＝（Ｘ₁₂ ² ＋Ｙ₁₂ ² ）^1/2 …▲５▼
Ｌ₂₃＝（Ｘ₂₃ ² ＋Ｙ₂₃ ² ）^1/2 …▲６▼
Ｌ₁₃＝（Ｘ₁₃ ² ＋Ｙ₁₃ ² ）^1/2 …▲７▼
ここで、第１基準ノードＮ₁ （Ｘ₁ ，Ｙ₁ ）と第３基準ノードＮ₃ （Ｘ₃ ，Ｙ₃ ）とを結ぶベクトルを、ベクトルＶ₁₃（Ｘ₁₃，Ｙ₁₃）とした。
【００５０】
図１１から明らかなように、３個の基準ノードＮ₁ 〜Ｎ₃ が共通の円弧上に存在すると仮定したとき、即ちカーブが円弧状カーブであるとき、Ｌ₁₂≒Ｌ₂₃であれば円弧状カーブの曲率半径Ｒは、
Ｒ＝Ｌ₁₃／（２ sinθ） …▲８▼
により求められ、この曲率半径Ｒに基づいてカーブの通過可否を判定することができる。
【００５１】
上述のようにして３個の基準ノードＮ₁ 〜Ｎ₃ から角度θ及び距離Ｌ₁₃が求められると、その角度θの大小と距離Ｌ₁₃の大小とに基づいて道路形状を判定することができる。即ち、図１２に示すように、角度θが大きく且つ距離Ｌ₁₃が小さい程カーブの曲率半径が小さく、また角度θが小さく且つ距離Ｌ₁₃が大きい程カーブの曲率半径が大きいことになる。
【００５２】
ところで、３個の基準ノードＮ₁ 〜Ｎ₃ が共通の円弧上に存在する場合、即ちカーブが円弧状カーブであれば、前記図１２に示すように道路形状を判定することができるが、円弧状カーブ以外の曲率半径が次第に減少するカーブ入口や曲率半径が次第に増加するカーブ出口は次のようにして判定することができる。
【００５３】
図１４に示すように、３個の基準ノードＮ₁ 〜Ｎ₃ が共通の円弧上にあると仮定して前述したように曲率半径Ｒを演算し、ベクトルＶ₁₂，Ｖ₂₃の長い方と曲率半径Ｒの円弧との較差を求める。そして求めた較差が基準値ｋの範囲内に納まっていれば、３個の基準ノードＮ₁ 〜Ｎ₃ が曲率半径Ｒの円弧上にあることが確認されるが、求めた較差が基準値ｋを越えていれば、３個の基準ノードＮ₁ 〜Ｎ₃ が前記円弧上に存在することは有り得ず、３個の基準ノードＮ₁ 〜Ｎ₃ 曲率半径が次第に変化する非円弧曲線（即ち、カーブ入口又はカーブ出口）上にあると判定される。
【００５４】
これを更に詳述すると、図１３に示すように、第１基準ノードＮ₁ と第２基準ノードＮ₂ との距離Ｌ₁₂が第２基準ノードＮ₂ と第３基準ノードＮ₃ との距離Ｌ₂₃よりも大きく、第１基準ノードＮ₁ と第２基準ノードＮ₂ とを結ぶベクトルＶ₁₂と３個の基準ノードＮ₁ 〜Ｎ₃ を通る円弧との較差が基準値ｋを越えていれば、道路形状は曲率半径が次第に減少するカーブ入口であると判定される。一方、距離Ｌ₂₃が距離Ｌ₁₂よりも大きく、ベクトルＶ₂₃と円弧との較差が基準値ｋを越えていれば、道路形状は曲率半径が次第に増加するカーブ出口であると判定される。
【００５５】
而して、図１５において、角度θが大きく距離Ｌ₁₃が小さい右下の領域は曲率半径Ｒが小さい急激なカーブ、交差点、分岐路等に対応し、角度θが小さく距離Ｌ₁₃が大きい右下の領域は曲率半径Ｒが大きい緩やかなカーブや直線路に対応する。また、ｋ₁ 〜ｋ₄ は較差の基準値を表しており（ｋ₁ ＞ｋ₂ ＞ｋ₃ ＞ｋ₄ ）、演算した角度θ及び距離Ｌ₁₃により決定されるポイントが、例えば基準値ｋ₂ の左下の領域にあれば道路形状は曲率半径は一定な円弧曲線であり、前記基準値ｋ₂ の右上の領域にあれば道路形状は曲率半径が次第に変化する非円弧曲線である。
【００５６】
判定した道路形状が非円弧曲線である場合、カーブの通過可否を判定するための曲率半径は以下のようにして求められる。即ち、図１４において求めた曲率半径Ｒは実際の曲率半径を反映しておらず、カーブ出口付近（即ち、第２基準ノードＮ₂ 及び第３基準ノードＮ₃ 付近）の実際の曲率半径は前記曲率半径Ｒよりも小さくなる。そこで、第１基準ノードＮ₁ 及び第２基準ノードＮ₂ を結ぶ線分上に第２基準ノードＮ₂ から距離Ｌ₂₃の位置Ｎ₁ ′を取り、３点Ｎ₁ ′，Ｎ₂ ，Ｎ₃ を通る円弧の曲率半径Ｒ′を求めれば、この曲率半径Ｒ′がカーブの通過可否を判定するための適切な曲率半径となる。
【００５７】
以上、本発明の実施例を詳述したが、本発明は前記実施例に限定されるものでなく、種々の設計変更を行うことが可能である。
【００５８】
【発明の効果】
以上のように、請求項１に記載された発明によれば、自車位置よりも前方の道路上において抽出された第１〜第４基準座標点のうち最も自車位置に近い第１基準座標点とそれの前方に隣接する第２基準座標点とを結ぶ線分と、第２基準座標点とそれの前方に隣接する第３基準座標点とを結ぶ線分との成す第１の角度、並びに第１及び第２基準座標点相互を結ぶ線分と、第２基準座標点と第３基準座標点の前方に隣接する第４基準座標点とを結ぶ線分との成す第２の角度を演算し、これら第１，第２の角度に基づいて道路の曲がりの大小を判定しているので、設備費や維持費が嵩むインフラストラクチャーの整備を必要とせず、しかもＣＤ−ＲＯＭやＩＣカードに記憶可能な最小限のデータ量で道路形状を判定することが可能となる。
【００５９】
また請求項２に記載された発明によれば、自車位置よりも前方の道路上において抽出された第１〜第３基準座標点のうち最も手前側の第１基準座標点とそれの前方に隣接する第２基準座標点とを結ぶ線分と、第２基準座標点とそれの前方に隣接する第３基準座標点とを結ぶ線分との成す角度を演算すると共に、前記第１基準座標点と第３基準座標点間の距離を演算し、これらの角度の大小と前記距離の大小とに基づいて道路形状を判定しているので、設備費や維持費が嵩むインフラストラクチャーの整備を必要とせず、しかもＣＤ−ＲＯＭやＩＣカードに記憶可能な最小限のデータ量で道路形状を判定することが可能となる。
しかも仮自車位置設定手段は、自車位置を基準として、現在の車速に基づいて自車位置よりも前方の道路上に仮自車位置を設定し、或いは自車位置を基準として、所定の減速度で制動を行った場合の停止距離に基づいて自車位置よりも前方の道路上に仮自車位置を設定し、前後に並ぶ少なくとも３個の基準座標点のうちの最前端の基準座標点が前記仮自車位置となるようにしたので、判定した道路形状に応じて乗員が減速や操舵を行うための充分な時間的余裕を与えることができる。
【００６０】
また請求項３に記載された発明によれば、自車位置よりも所定距離前方の道路上に仮自車位置を設定し、この仮自車位置を前記基準座標点の１つとしているので、判定した道路形状に応じて乗員が減速や操舵を行うための充分な時間的余裕を与えることができる。
【００６１】
また請求項４に記載された発明によれば、判定した道路形状を乗員に表示する表示手段を備えているので、道路形状を確実に乗員に報知することができる。
【図面の簡単な説明】
【図１】本発明装置の全体構成を示すブロック図
【図２】制御系のブロック図
【図３】作用を示すフローチャート
【図４】道路形状の求め方を示す説明図
【図５】基準座標点の抽出方法の説明図
【図６】道路形状のパターンを示す図
【図７】道路形状の判定基準を示す図
【図８】第２実施例に係る、前記図２に対応するブロック図
【図９】較差の説明図
【図１０】道路形状の求め方を示す説明図
【図１１】円弧カーブの曲率半径の求め方を示す説明図
【図１２】道路形状のパターンを示す図
【図１３】道路形状のパターンを示す図
【図１４】非円弧カーブの判定法を示す説明図
【図１５】道路形状の判定基準を示す図
【符号の説明】
Ｍ１ 地図情報出力手段
Ｍ２ 自車位置出力手段
Ｍ３ 基準座標点抽出手段
Ｍ４ 角度演算手段
Ｍ５ 道路形状判定手段
Ｍ６ 距離演算手段
Ｍ７ 表示手段
Ｎ₁ 〜Ｎ₄ 基準ノード（基準座標点）
Ｎ₁ 〜Ｎ₃ 基準ノード（基準座標点）
θ₁ ，θ₂ 角度
θ 角度
Ｌ₁₃ 距離[0001]
[Industrial application fields]
The present invention relates to a road shape determination device that determines the shape of the road based on map information as a set of a plurality of coordinate points constituting the road.
[0002]
[Prior art]
Information on road shape is given to vehicle occupants by transmitting information on approach speed and steering angle necessary for smoothly passing the curve from a transmitter provided in front of the curve entrance No. 149700), or one that controls an auto-cruise device of an automobile based on information on road gradient, road surface condition, curve radius stored in a CD-ROM (see Japanese Patent Laid-Open No. 4-15799) is known. ing.
[0003]
[Problems to be solved by the invention]
By the way, the former is difficult to install on all roads due to increased equipment costs and maintenance costs, and the latter has a problem that its feasibility is poor due to the enormous amount of data.
[0004]
The present invention has been made in view of the above-described circumstances, and an object thereof is to accurately determine the road shape ahead of the host vehicle based on map information including a set of a plurality of coordinate points constituting the road.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 outputs map information output means for outputting map information as a set of a plurality of coordinate points constituting the road, and outputs the position of the vehicle on the road. Own vehicle position output means, reference coordinate point extraction means for extracting at least four reference coordinate points on the road ahead of the own vehicle position, and first to fourth references extracted by the reference coordinate point extraction means A line segment connecting the first reference coordinate point closest to the vehicle position among the coordinate points and the second reference coordinate point adjacent in front thereof, and the second reference coordinate point and the third reference coordinate adjacent in front thereof A first angle formed by a line connecting the points, a line connecting the first and second reference coordinate points, and a fourth reference coordinate adjacent to the front of the second reference coordinate point and the third reference coordinate point. an angle calculating means for calculating a second angle formed between the line connecting the points, the Degree calculating the first calculated by means, characterized in that a road shape judging means for judging the magnitude of the bending of the road based on the second angle.
[0006]
The invention described in claim 2 is a map information output means for outputting map information as a set of a plurality of coordinate points constituting the road, a vehicle position output means for outputting the vehicle position on the road, When the temporary vehicle position is set on the road ahead of the vehicle position based on the current vehicle speed based on the current vehicle position, or braking is performed at a predetermined deceleration based on the vehicle position Temporary vehicle position setting means for setting the temporary vehicle position on the road ahead of the vehicle position based on the stop distance, and at least three reference coordinate points arranged in front and back on the road ahead of the vehicle position , The reference coordinate point extracting means for extracting the frontmost reference coordinate point to be the position of the temporary vehicle, and the first to third reference coordinate points that are extracted by the reference coordinate point extracting means and arranged in the front-rear direction. The first reference coordinate point on the foremost side and the front of it Angle calculating means for calculating an angle formed by a line segment connecting the adjacent second reference coordinate point and a line segment connecting the second reference coordinate point and the third reference coordinate point adjacent to the second reference coordinate point; A distance calculating means for calculating a distance between one reference coordinate point and a third reference coordinate point; and a road shape determining means for determining a road shape based on the magnitude of the angle and the magnitude of the distance. And
[0007]
According to a third aspect of the present invention, in addition to the configuration of the first aspect , a temporary vehicle position is set on a road ahead of the vehicle position by a predetermined distance, and the temporary vehicle position is set as the reference coordinate point. It is characterized by being one of these.
[0008]
According to a fourth aspect of the invention, in addition to the configuration of the first or second aspect, the invention includes a display unit that displays the determined road shape to an occupant.
[0009]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0010]
1 to 7 show a first embodiment of the present invention. FIG. 1 is a block diagram showing the overall configuration of the apparatus of the present invention, FIG. 2 is a block diagram of a control system, and FIG. 3 is a flowchart showing the operation. 4 is an explanatory diagram showing how to determine the road shape, FIG. 5 is an explanatory diagram of a method for extracting reference coordinate points, FIG. 6 is a diagram showing a road shape pattern, and FIG. 7 is a diagram showing road shape determination criteria.
[0011]
In FIG. 1, NV is an automobile navigation system, which includes a known navigation device 1, a map information output means 2 using an IC card or a CD-ROM, and a control unit 3 that performs various calculations described later. .
[0012]
The navigation device 1 receives a signal from the vehicle speed detection means 6 in addition to the own vehicle position information, road information, traffic information, etc. from the satellite communication device 4 or the proximity communication device 5, and receives this signal from the map information output means 2 Based on the map information, the current position of the vehicle and the route to the destination are calculated and displayed on the CRT 9 via the man-machine interface 8.
[0013]
The map information output by the map information output means 2 is composed of a set of virtual nodes N arranged on the road, and each node N is defined by coordinates N (X, Y). When there are bending points, branch points, and intersections on the road, those singular points are preferentially selected as the node N.
[0014]
The control unit 3 performs various calculations to be described later based on the outputs of the navigation device 1, the map information output means 2, and the vehicle speed detection means 6, displays the results, and performs alarms and vehicle speed control.
[0015]
C is a vehicle speed adjusting device, and includes an image creating means 11, an alarm means 12, and a vehicle speed adjusting means 13 therein. The image creating means 11 is composed of a head-up display, for example, and displays the determined road shape in front, the vehicle speed that can be passed, and the like. The warning means 12 is composed of sound means such as a buzzer and a chime, and issues various warnings to the occupant. The vehicle speed adjusting means 13 comprises a brake device, an auto cruise device, etc., and automatically adjusts the vehicle speed so that it can pass through a curve.
[0016]
FIG. 2 is a block diagram showing a control system of the present invention, in which map information output means M1 corresponding to the map information output means 2, own vehicle position output means M2 corresponding to the navigation device 1, and the control section 3, reference coordinate point extracting means M3, angle calculating means M4, road shape determining means M5, and display means M7 corresponding to the image creating means 11.
[0017]
The reference coordinate point extraction means M3 extracts four nodes N ₁ , N ₂ , N ₃ , N ₄ (hereinafter referred to as reference nodes) for determining the road shape from a large number of nodes N set on the road. To do.
[0018]
The angle calculation means M4 calculates an angle θ ₁ formed by a vector V ₁₂ which is a vector connecting the reference nodes N ₁ and N ₂ and a vector V ₂₃ which is a vector connecting the reference nodes N ₂ and N ₃ , and the reference node An angle θ ₂ formed by a vector V ₁₂ that is a vector connecting N ₁ and N ₂ and a vector V ₂₄ that is a vector connecting the reference nodes N ₂ and N ₄ is calculated, and a road shape is determined from the angles θ ₁ and θ _2. The rate of change α for is calculated. The calculation method of the change rate α will be described in detail later.
[0019]
The road shape determination means M5 determines the road shape by comparing the change rate α with a predetermined reference value.
[0020]
Next, the operation of the first embodiment of the present invention will be described based on the flowchart of FIG.
[0021]
First, the map information (that is, the coordinates N (X, Y) of the node N) is read from the map information output means M1, and the own vehicle position P ₀ (X ₀ , Y ₀ ) is read from the own vehicle position output means M2. The vehicle speed V ₀ is read from the detection means 6 (step S1).
[0022]
Next, the prefetch section S ₁ and the determination section S ₂ are calculated (step S2). As shown in FIG. 4, the prefetch section S ₁ is set in front of the vehicle position P ₀ , and is the product of the current vehicle speed V ₀ and the predetermined time t ₁ (S ₁ = V ₀ × t ₁ ). is set as - distance to stop within a predetermined time ^{_{t 1 ((βt 1 2/}} 2) S 1 = V 0 t 1) when either set, or subjected to braking at a predetermined deceleration β . The pre-reading section S ₁ is used to give a passenger a time margin for braking and steering after determining the road shape ahead of the host vehicle.
[0023]
The determination section S ₂ is set to a predetermined range ahead with respect to the front end of the pre-read section S ₁ (hereinafter referred to as the temporary vehicle position). For example, the determination section S ₂ is a product of the current vehicle speed V ₀ and a predetermined time t ₂ ( S ₂ = V ₀ × t ₂ ).
[0024]
Next, the reference coordinate point extraction means M3 extracts four nodes N _{1 to} N ₄ (hereinafter referred to as reference nodes N _{1 to} N ₄ ) for determining the road shape (step S3). The second reference node N ₂ is set at the temporary vehicle position, the first reference node N ₁ is at the front position by the distance a of the second reference node N ₂ , and the third reference node N ₃ is at the second reference node N _2. And the fourth reference node N ₄ is set to the front position by the distance a of the third reference node N ₃ . Here, a is set as a constant or the product of the vehicle speed V ₀ and the predetermined time t ₃ (a = V ₀ × t ₃ ).
[0025]
When the node N does not exist at a position set by a multiple of the distance a with reference to the temporary vehicle position, the node N closest to the position is extracted as the reference nodes N _{1 to} N ₄ .
[0026]
In this embodiment, the reference nodes N _{1 to} N ₄ are extracted at substantially equal intervals. However, when there are few nodes N set on the road (that is, when the nodes are sparse), the adjacent nodes N are selected. You may extract as it is.
[0027]
In addition, as shown in FIG. 5A, the S-curve has the most severe passage condition in the composite curve, but when the distance a is set as a constant, if a = 30 m, the radius of curvature is set. A compact S-curve connecting two arcs of R = 30 m can also be reliably determined.
[0028]
Furthermore, as shown in FIG. 5 (B), when the road is bent in a crank path and the like to the judgment section S ₂ is present, preferentially relative to the node corresponding to the bent point N (singular point) Extracted as nodes N _{1 to} N ₄ . Thereby, special road shapes, such as a crank road, can be determined reliably.
[0029]
Next, the road shape is determined based on the coordinates of the _four reference nodes N _{1 to} N ₄ (step S4).
[0030]
First, the angles θ ₁ and θ ₂ are calculated by the angle calculation means M4. That is, as shown in FIG. 4, a vector V ₁₂ (X ₁₂ , Y ₁₂ ) connecting the first reference node N ₁ (X ₁ , Y ₁ ) and the second reference node N ₂ (X ₂ , Y ₂ ) and , A vector V ₂₃ (X ₂₃ , Y ₂₃ ) connecting the second reference node N ₂ (X ₂ , Y ₂ ) and the third reference node N ₃ (X ₃ , Y ₃ ) to the second reference node N ₂ ( A vector V ₂₄ (X ₂₄ , Y ₂₄ ) connecting X ₂ , Y ₂ ) and the fourth reference node N ₄ (X ₄ , Y ₄ ) is calculated.
[0031]
In this case, when the angle formed by the vector V ₁₂ and the vector V ₂₃ and theta _1, from the inner product of the vector V ₁₂ and the vector V _23,

From this, cos θ ₁ is obtained.
[0032]
If the angle formed by the vector V ₁₂ and the vector V ₂₄ is θ ₂ , the inner product of the vector V ₁₂ and the vector V ₂₄ is

From this, cos θ ₂ is obtained.
[0033]
Next, the change rate α is set to α = (cosθ ₁ −cosθ ₂ ) / cosθ ₁ (3)
Calculate by
[0034]
As is clear from the equation (3), when the absolute value of the rate of change α is small, this corresponds to the case where θ ₁ and θ ₂ are approximately the same and the road curve is small (ie, a straight road) Conversely, when the absolute value of the rate of change α is large, this corresponds to a case where θ ₁ and θ ₂ are greatly different and the road is curved (that is, a crank road or a sharp curve).
[0035]
Incidentally, the bending direction of the road can be determined by the sign of the vector V ₁₂ and outer product of the vector V _23, namely _{X 12 · Y 23 -Y 12 ·} X 23.
[0036]
Thus, as shown in FIGS. 6 and 7, the road shape determining means M5 determines various road shapes according to the value of the change rate α.
[0037]
If the road shape determined as described above is a curve (step S4), it is further determined whether the curve is an S-shaped curve or a crank road (step S5). If the road shape is a simple curve, a notice of the curve is displayed on the display means M7 (step S6). If the road shape is difficult to pass through, the S-curve or crank is displayed on the display means M7. A road notice is displayed (step S7).
[0038]
Next, it is determined whether or not the current vehicle speed V ₀ is appropriate for the determined road shape (step S8), and if the current vehicle speed V ₀ is excessive with respect to the vehicle speed that can turn a curve ahead, warning means is provided. 12, a warning is issued to the passenger (step S9). If the vehicle is not decelerated to an appropriate vehicle speed at which the curve can be reliably turned in spite of the alarm (step S10), automatic deceleration is performed by the vehicle speed adjusting means 13 (step S11). When the vehicle passes the target curve or the vehicle speed V ₀ is decelerated to the appropriate vehicle speed (step S12), the automatic deceleration is stopped and the process returns to step S1.
[0039]
On the other hand, If the answer of the step S8, S10 is is unnecessary automatic deceleration in NO, it is determined whether the process has been performed for the entire area of the judgment section S ₂ (step S13), and the judgment section the answer is NO if not processing the entire area of S ₂ is finished to return to the step S3, the reference node N ₁ to N ₄ and is shifted to the front side repeats the processing described above, as a result the answer at step S13 is all turned YES When the process is completed, the process returns to step S1.
[0040]
As described above, since the road shape is determined based on the map information composed of the coordinates N (X, Y) of the plurality of nodes N, it is not necessary to maintain the infrastructure that increases the equipment cost and the maintenance cost. In addition, the road shape can be determined with the minimum amount of data that can be stored in a CD-ROM or IC card.
[0041]
Next, a second embodiment of the present invention will be described with reference to FIGS. 8 is a block diagram corresponding to FIG. 2 of the first embodiment, FIG. 9 is an explanatory diagram of the difference, FIG. 10 is an explanatory diagram showing how to obtain the road shape, and FIG. 11 is a method of obtaining the curvature radius of the arc curve. 12 is an explanatory diagram, FIG. 12 is a diagram showing a road shape pattern, FIG. 13 is a diagram showing a road shape pattern, FIG. 14 is an explanatory diagram showing a method for determining a non-arc curve, and FIG. It is.
[0042]
In the second embodiment, the road shape is determined on the basis of _three reference nodes N ₁ , N ₂ , and N ₃ adjacent to each other. As shown in FIG. 8, the output of the angle calculation means M4 and the distance calculation means M6 The second embodiment is different from the first embodiment in that the road shape is determined based on the output of the other, and the other configuration is the same as the first embodiment.
[0043]
Note that the map information of the second embodiment is a rule for data creation, and each node N is set so that the distance between the line segment connecting adjacent nodes N and the road (hereinafter referred to as a difference) is equal to or less than a predetermined reference value k. The position of is determined. That is, as shown in FIG. 9, in a portion where the radius of curvature of the road is small, the difference is suppressed to a reference value k or less by setting the distance between adjacent nodes N small.
[0044]
The extraction of the _three reference nodes N ₁ , N ₂ , N ₃ is performed as follows. That is, the first reference node N ₁ on the most front side among the three reference nodes to be first extracted N _1, N _2, N ₃ is set to the tip of the pre-read interval S _1, nodes adjacent to the front N is the second reference node N _2, and the node N adjacent in front of the second reference node N ₂ is the third reference node N ₃ . These three reference nodes N ₁ , N ₂ , N ₃ are sequentially extracted while being shifted forward.
[0045]
Next, a method for determining the road shape based on the coordinates of the _three reference nodes N _{1 to} N ₃ will be described. .
[0046]
First, as shown in FIG. 10, a vector V ₁₂ (X ₁₂ ) connecting the first reference node N ₁ (X ₁ , Y ₁ ) and the second reference node N ₂ (X ₂ , Y ₂ ) by the angle calculation means M4. , Y ₁₂ ) and an angle formed by a vector V ₂₃ (X ₂₃ , Y ₂₃ ) connecting the second reference node N ₂ (X ₂ , Y ₂ ) and the third reference node N ₃ (X ₃ , Y ₃ ). Calculate θ.
[0047]
That is, from the inner product of vector V ₁₂ and vector V ₂₃ ,

From this, the angle θ is obtained.
[0048]
Next, a distance L ₁₂ between the first reference node N ₁ (X ₁ , Y ₁ ) and the second reference node N ₂ (X ₂ , Y ₂ ) and the second reference node N ₂ (X _2, Y ₂₎ and the third reference node N ₃ (X _3, Y ₃₎ and the distance L ₂₃ between the first reference node N ₁ (X _1, Y ₁₎ and the third reference node N ₃ (X _3, Y ₃ ) and the distance L ₁₃ are calculated.
[0049]
L ₁₂ = (X ₁₂ ² + Y ₁₂ ² ) ^1/2 ... (5)
L ₂₃ = (X ₂₃ ² + Y ₂₃ ² ) ^1/2 ... (6)
L ₁₃ = (X ₁₃ ² + Y ₁₃ ² ) ^1/2 ... (7)
Here, a vector connecting the first reference node N ₁ (X ₁ , Y ₁ ) and the third reference node N ₃ (X ₃ , Y ₃ ) is defined as a vector V ₁₃ (X ₁₃ , Y ₁₃ ).
[0050]
As apparent from FIG. 11, when it is assumed that the _three reference nodes N _{1 to} N ₃ exist on a common arc, that is, when the curve is an arcuate curve, if L ₁₂ ≈L ₂₃ , the arc shape The radius of curvature R of the curve is
R = L ₁₃ / (2 sin θ) (8)
Based on this radius of curvature R, it is possible to determine whether or not the curve can pass.
[0051]
When the angle θ and the distance L ₁₃ are obtained from the _three reference nodes N _{1 to} N ₃ as described above, the road shape can be determined based on the size of the angle θ and the size of the distance L _13. . That is, as shown in FIG. 12, the radius of curvature of the curve is smaller as the angle θ is larger and the distance L ₁₃ is smaller, and the radius of curvature of the curve is larger as the angle θ is smaller and the distance L ₁₃ is larger.
[0052]
By the way, when the three reference nodes N _{1 to} N ₃ exist on a common arc, that is, if the curve is an arcuate curve, the road shape can be determined as shown in FIG. The curve entrance other than the arcuate curve where the radius of curvature gradually decreases and the curve exit where the radius of curvature gradually increases can be determined as follows.
[0053]
As shown in FIG. 14, assuming that the _three reference nodes N _{1 to} N ₃ are on a common arc, the curvature radius R is calculated as described above, and the longer one of the vectors V ₁₂ and V ₂₃ and the curvature are calculated. The difference between the radius R and the arc is obtained. If the obtained difference is within the range of the reference value k, it is confirmed that the _three reference nodes N _{1 to} N ₃ are on the arc of the radius of curvature R, but the obtained difference is the reference value k. 3, the three reference nodes N _{1 to} N ₃ cannot exist on the arc, and the three reference nodes N _{1 to} N ₃ have a non-arc curve in which the radius of curvature gradually changes (that is, It is determined that it is on the curve entrance or curve exit).
[0054]
More specifically, as shown in FIG. 13, the distance L ₁₂ between the first reference node N ₁ and the second reference node N ₂ is the distance L between the second reference node N ₂ and the third reference node N _{3. If} the difference between the vector V ₁₂ connecting the first reference node N ₁ and the second reference node N ₂ and the arc passing through the _three reference nodes N _{1 to} N ₃ exceeds the reference value k. The road shape is determined to be a curve entrance where the radius of curvature gradually decreases. On the other hand, the distance L ₂₃ is greater than the distance L _12, if beyond the hidden reference value k of the vector V ₂₃ and an arc, a road shape is judged to be curve exit radius of curvature is increased gradually.
[0055]
Thus, in FIG. 15, the lower right region where the angle θ is large and the distance L ₁₃ is small corresponds to a sharp curve, intersection, branch road or the like having a small radius of curvature R, and the right angle L is small and the distance L ₁₃ is large. The lower region corresponds to a gentle curve or straight road having a large curvature radius R. K _{1 to} k ₄ represent reference values for the difference (k ₁ > k ₂ > k ₃ > k ₄ ), and the point determined by the calculated angle θ and distance L ₁₃ is, for example, the reference value k _2. road shape if the bottom left of the area radius of curvature is constant arc curved road shape if the upper right area of the reference value k ₂ are non-arc curve curvature radius changes gradually.
[0056]
When the determined road shape is a non-circular curve, the radius of curvature for determining whether or not the curve can pass is obtained as follows. That is, the radius of curvature R obtained in FIG. 14 does not reflect the actual radius of curvature, and the actual radius of curvature near the curve exit (ie, near the second reference node N ₂ and the third reference node N ₃ ) It becomes smaller than the curvature radius R. Therefore, a position N ₁ ′ at a distance L ₂₃ from the second reference node N ₂ is taken on a line segment connecting the first reference node N ₁ and the second reference node N ₂ , and three points N ₁ ′, N ₂ , N _{3 are taken.} If the radius of curvature R ′ of the arc passing through is obtained, this radius of curvature R ′ becomes an appropriate radius of curvature for determining whether or not the curve can pass.
[0057]
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various design change is possible.
[0058]
【The invention's effect】
As described above, according to the first aspect of the present invention, the first reference coordinate closest to the vehicle position among the first to fourth reference coordinate points extracted on the road ahead of the vehicle position. A first angle formed by a line segment connecting the point and a second reference coordinate point adjacent in front of the point and a line segment connecting the second reference coordinate point and a third reference coordinate point adjacent in front thereof; And a second angle formed by a line segment connecting the first and second reference coordinate points and a line segment connecting the second reference coordinate point and the fourth reference coordinate point adjacent to the front of the third reference coordinate point. Because it calculates and determines the magnitude of the road turn based on these first and second angles, it does not require infrastructure maintenance that increases equipment and maintenance costs, and it is also possible to use a CD-ROM or IC card. It becomes possible to determine the road shape with the minimum amount of data that can be stored.
[0059]
According to the invention described in claim 2, the first reference coordinate point closest to the first reference coordinate point extracted on the road ahead of the vehicle position and the front thereof. An angle formed by a line segment connecting the adjacent second reference coordinate point and a line segment connecting the second reference coordinate point and the third reference coordinate point adjacent to the second reference coordinate point is calculated, and the first reference coordinate is calculated. Since the distance between the point and the third reference coordinate point is calculated and the road shape is determined based on the size of these angles and the size of the distance, it is necessary to develop an infrastructure that increases equipment costs and maintenance costs. In addition, the road shape can be determined with a minimum amount of data that can be stored in a CD-ROM or IC card.
Moreover, the provisional vehicle position setting means sets the provisional vehicle position on the road ahead of the vehicle position based on the current vehicle speed based on the vehicle position, or sets the predetermined position based on the vehicle position. Based on the stopping distance when braking is performed at deceleration, the temporary vehicle position is set on the road ahead of the vehicle position, and the reference coordinates at the forefront of at least three reference coordinate points arranged in front and back Since the point is the temporary vehicle position, it is possible to give a sufficient time margin for the occupant to decelerate or steer according to the determined road shape.
[0060]
According to the invention described in claim 3, since the temporary vehicle position is set on the road ahead of the vehicle position by a predetermined distance, and the temporary vehicle position is set as one of the reference coordinate points . A sufficient time margin can be provided for the occupant to decelerate or steer according to the determined road shape.
[0061]
According to the invention described in claim 4, since the display means for displaying the determined road shape to the occupant is provided, the road shape can be notified to the occupant with certainty.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the overall configuration of the apparatus of the present invention. FIG. 2 is a block diagram of a control system. FIG. 3 is a flowchart showing an operation. FIG. 4 is an explanatory diagram showing how to determine a road shape. FIG. 6 is a diagram showing a road shape pattern. FIG. 7 is a diagram showing a road shape judgment criterion. FIG. 8 is a block diagram corresponding to FIG. 2 according to a second embodiment. FIG. 9 is an explanatory diagram of the difference. FIG. 10 is an explanatory diagram showing how to obtain the road shape. FIG. 11 is an explanatory diagram showing how to obtain the curvature radius of the arc curve. FIG. 12 is a diagram showing the road shape pattern. [Figure] Diagram showing road shape pattern [Fig. 14] Explanatory diagram showing non-arc curve judgment method [Fig. 15] Diagram showing judgment criteria for road shape [Explanation of symbols]
M1 Map information output means M2 Vehicle position output means M3 Reference coordinate point extraction means M4 Angle calculation means M5 Road shape determination means M6 Distance calculation means M7 Display means N _{1 to} N ₄ reference nodes (reference coordinate points)
N ₁ to N ₃ reference node (reference coordinate point)
θ ₁ , θ ₂ angle θ angle L ₁₃ distance

Claims (4)

Map information output means (M1) for outputting map information as a set of a plurality of coordinate points constituting the road;
A vehicle position output means (M2) for outputting the vehicle position on the road;
Reference coordinate point extraction means (M3) for extracting at least four reference coordinate points (N _{1 to} N ₄ ) on the road ahead of the vehicle position;
Among the first to fourth reference coordinate points (N _{1 to} N ₄ ) extracted by the reference coordinate point extraction means (M3), the first reference coordinate point (N ₁ ) closest to the vehicle position and in front of it. A line segment connecting the adjacent second reference coordinate point (N ₂ ) and a line segment connecting the second reference coordinate point (N ₂ ) and the third reference coordinate point (N ₃ ) adjacent in front of the second reference coordinate point (N ₂ ) A first angle (θ ₁ ) formed, a line segment connecting the first and second reference coordinate points (N ₁ , N ₂ ), a second reference coordinate point (N ₂ ), and a third reference coordinate point (N ₃ ) Angle calculating means (M4) for calculating a _second angle (θ ₂ ) formed by a line segment connecting the fourth reference coordinate point (N ₄ ) adjacent to the front of
Road shape determination means (M5) for determining the magnitude of the curve of the road based on the first and second angles (θ ₁ , θ ₂ ) calculated by the angle calculation means (M4);
A road shape determining apparatus comprising: Map information output means (M1) for outputting map information as a set of a plurality of coordinate points constituting the road;
A vehicle position output means (M2) for outputting the vehicle position on the road;
When the temporary vehicle position is set on the road ahead of the vehicle position based on the current vehicle speed based on the current vehicle position, or braking is performed at a predetermined deceleration based on the vehicle position Temporary vehicle position setting means for setting the temporary vehicle position on the road ahead of the vehicle position based on the stop distance, and at least three reference coordinate points arranged in front and back on the road ahead of the vehicle position Reference coordinate point extracting means (M3) for extracting (N _{1 to} N ₃ ) such that the frontmost reference coordinate point (N ₁ ) is the temporary vehicle position ;
Of the first to third reference coordinate points (N _{1 to} N ₃ ) extracted by the reference coordinate point extraction means (M3) and arranged before and after, the frontmost first reference coordinate point (N ₁ ) and its front side A line segment connecting the second reference coordinate point (N ₂ ) adjacent to the second reference coordinate point (N ₂ ) and a line segment connecting the second reference coordinate point (N ₂ ) and the third reference coordinate point (N ₃ ) adjacent to the second reference coordinate point (N ₃ ) Angle calculating means (M4) for calculating an angle (θ) formed by:
Distance calculating means (M6) for calculating a distance (L ₁₃ ) between the first reference coordinate point (N ₁ ) and the third reference coordinate point (N ₃ );
A road shape determination apparatus comprising road shape determination means (M5) for determining a road shape based on the magnitude of the angle (θ) and the magnitude of the distance (L ₁₃ ). A temporary vehicle position is set on a road ahead of the vehicle position by a predetermined distance, and the temporary vehicle position is set as _{one of the} reference coordinate points (N _{1 to} N ₄ ; N _{1 to} N ₃ ). The road shape determination apparatus according to claim 1.   The road shape determination device according to claim 1 or 2, further comprising display means (M7) for displaying the determined road shape to an occupant.

Images