JP3986681B2 - Vehicle travel safety device - Google Patents

Description

【００４５】
（６）式の右辺における５つの変数のうち、Ｖｉは常に算出可能であり、且つＶｓ，Ｌ，θ，εはレーダー装置３の１回の送受信で算出可能であるため、レーダー装置３で最初に対向車Ａｏを判別した時点で速やかに横偏差δｄを算出することができる。従って、自車Ａｉおよび対向車Ａｏが相互に接近するために接触時間ｔｃに余裕がない場合でも、速やかに接触可能性の判定を行なって衝突回避制御を開始することができる。
【００４６】
而して、図９のフローチャートのステップＳ４９で、前記横偏差δｄを予め設定した接触判定基準値と比較し、横偏差δｄが第１接触判定基準値δｄｎおよび第２接触判定基準値δｄｘの間にあれば、すなわちδｄｎ＜δｄ＜δｄｘが成立すれば、ステップＳ５０で自車Ａｉが対向車Ａｏに衝突する可能性があると判定する（図１３参照）。一方、図１４に示すようにδｄ≦δｄｎであれば、あるいは図１５に示すようにδｄ≧δｄｘであれば、ステップＳ５１で自車Ａｉが対向車Ａｏに衝突する可能性がないと判定する。図１５の状態は、例えば自車Ａｉが分岐路に進入するために対向車Ａｏの車線を斜めに横切るような場合に相当する。
【００４７】
尚、前記第１接触判定基準値δｄｎおよび第２接触判定基準値δｄｘは自車Ａｉの車幅等に応じて適宜設定されるもので、例えば第１接触判定基準値δｄｎ＝１．５ｍ、第２接触判定基準値δｄｘ＝４．５ｍとされる。
【００４８】
以上の説明では横偏差δｄを算出する際に自車Ａｉのヨーレートγｉおよび対向車Ａｏのヨーレートγｏを考慮していないが、それらヨーレートγｉ，γｏを考慮することにより、更に精度の高い衝突回避が行われる。
【００４９】
自車Ａｉが車速Ｖｉ、ヨーレートγｉで走行するとＶｉγｉの横加速度が発生するため、このＶｉγｉを２回積分することにより自車Ａｉの横方向移動量ｙｉが算出される。従って、接触時間ｔｃ＝Ｌ／Ｖｓにおける自車Ａｉの横方向移動量ｙｉは、
ｙｉ＝（Ｖｉ・γｉ／２）・（Ｌ／Ｖｓ）² …（７）
で与えられる。
【００５０】
同様に、対向車Ａｏが車速Ｖｏ、ヨーレートγｏで走行するとＶｏγｏの横加速度が発生するため、このＶｏγｏを２回積分することにより対向車Ａｏの横方向移動量ｙｏが算出される。従って、接触時間ｔｃ＝Ｌ／Ｖｓにおける対向車Ａｏの横方向移動量ｙｏは、
ｙｏ＝（Ｖｏ・γｏ／２）・（Ｌ／Ｖｓ）² …（８）
で与えられる。
【００５１】
而して、前記（６）式の横偏差δｄを自車Ａｉの横方向移動量ｙｉおよび対向車Ａｏの横方向移動量ｙｏで補正した次式を用いることにより、横偏差δｄの精度を一層高めることができる。
【００５２】
【数２】

【００５３】
対向車Ａｏのヨーレートγｏは、レーダー装置３の出力に基づいて対向車Ａｏの位置を複数回検出して該対向車Ａｏの旋回軌跡を推定すれば、その旋回半径と対向車Ａｏの車速Ｖｏとに基づいて算出される。従って、対向車Ａｏのヨーレートγｏはレーザー装置３の１回の送受信では検出することができず、（９）式における対向車Ａｏのヨーレートγｏを用いた補正を行うには若干の演算時間が必要になる。但し、図６のフローチャートのステップＳ１７で説明したように、この正面衝突回避制御は自車Ａｉが実質的に直線走行しているとき（直線路を走行しているとき）に行われるもので、このとき対向車Ａｏのヨーレートγｏが大きな値を持つことは稀である。このことから、対向車Ａｏのヨーレートγｏを用いた補正を行わなくても充分な精度を確保することができる。
【００５４】
ところで、前記第１接触判定基準値δｄｎおよび第２接触判定基準値δｄｘを固定値とする代わりに、第１接触判定基準値δｄｎおよび第２接触判定基準値δｄｘを横偏差δｄを算出した時点における自車Ａｉおよび対向車Ａｏの走行状態で補正すれば、正面衝突回避制御を更に精度良く行うことができる。すなわち、第１接触判定基準値δｄｎの補正は、３つの補正係数ｋ１ｎ，ｋ２ｎ，ｋ３ｎを用いて、
δｄｎ←ｋ１ｎ・ｋ２ｎ・ｋ３ｎ・δｄｎ …（１０）
のように行われ、第２接触判定基準値δｄｘの補正は３つの補正係数ｋ１ｘ，ｋ２ｘ，ｋ３ｘを用いて、
δｄｘ←ｋ１ｘ・ｋ２ｘ・ｋ３ｘ・δｄｘ …（１１）
のように行われる。
【００５５】
補正係数ｋ１ｎ，ｋ１ｘは、図１６（Ａ）に示すマップから衝突までの時間（接触時間ｔｃ）に基づいて検索される。接触時間ｔｃが小さいために横偏差δｄの算出誤差が小さいと推定される領域では、補正係数ｋ１ｎ，ｋ１ｘは１に保持される。接触時間ｔｃが大きいために横偏差δｄの算出誤差が大きいと推定される領域では、補正係数ｋ１ｎは接触時間ｔｃの増加に伴って１から増加するとともに、補正係数ｋ１ｘは接触時間ｔｃの増加に伴って１から減少する。これにより、横偏差δｄの算出誤差が大きい領域で第１接触判定基準値δｄｎおよび第２接触判定基準値δｄｘの間の幅を小さくし、不確実な正面衝突回避制御が行われるのを回避することができる。
【００５６】
補正係数ｋ２ｎ，ｋ２ｘは、図１６（Ｂ）に示すマップから自車Ａｉと対向車Ａｏとの相対距離Ｌに基づいて検索される。相対距離Ｌが小さいために横偏差δｄの算出誤差が小さいと推定される領域では、補正係数ｋ２ｎ，ｋ２ｘは１に保持される。相対距離Ｌが大きいために横偏差δｄの算出誤差が大きいと推定される領域では、補正係数ｋ２ｎは相対距離Ｌの増加に伴って１から増加するとともに、補正係数ｋ２ｘは相対距離Ｌの増加に伴って１から減少する。これにより、横偏差δｄの算出誤差が大きい領域で第１接触判定基準値δｄｎおよび第２接触判定基準値δｄｘの間の幅を小さくし、不確実な正面衝突回避制御が行われるのを回避することができる。
【００５７】
補正係数ｋ３ｎ，ｋ３ｘは、図１６（Ｃ）に示すマップから自車Ａｉのヨーレートγｉに基づいて検索される。自車Ａｉのヨーレートγｉが０であって横偏差δｄの算出誤差が小さいと推定されるときには、補正係数ｋ３ｎ，ｋ３ｘは１に設定される。自車Ａｉのヨーレートγｉの増加に伴って横偏差δｄの算出誤差が増加すると補正係数ｋ３ｎは１から増加するとともに、補正係数ｋ３ｘは１から減少する。これにより、横偏差δｄの算出誤差が大きい領域で第１接触判定基準値δｄｎおよび第２接触判定基準値δｄｘの間の幅を小さくし、不確実な正面衝突回避制御が行われるのを回避することができる。
【００５８】
次に、前記ステップＳ２３の「警報制御」の内容を、図１０のフローチャートに基づいて説明する。
【００５９】
先ず、ステップＳ６１で衝突情報を受信する。衝突情報とは、接触時間ｔｃ（衝突までの時間）、接触位置Ｐでの自車Ａｉおよび対向車Ａｏの走行状態、横偏差δｄ等である。続くステップＳ６２で一次警報の判断を行い、接触時間ｔｃが例えば４秒未満になると、ステップＳ６３で警報器５を作動させて一次警報を開始する。続いてステップＳ６４で二次警報の判断を行い、接触時間ｔｃが例えば３秒未満になると、ステップＳ６５で警報器５を作動させて二次警報を開始する。一次警報は衝突までの時間的余裕が比較的に大きい場合に実行され、また二次警報は衝突までの時間的余裕が比較的に小さい場合に実行されるもので、その差異をドライバーに認識させるべくブザーの音色等やランプの色を変化させる。ドライバーは警報器５による警報により衝突の危険を認識して自発的な回避操作を行うことができる。
【００６０】
次に、前記ステップＳ２４の「回避操舵制御」の内容を、図１１のフローチャートに基づいて説明する。
【００６１】
先ず、ステップＳ７１で、前記ステップＳ６１と同様に衝突情報を受信した後に、続くステップＳ７２で操舵開始の判断を行い、接触時間ｔｃが前記二次警報の閾値である３秒よりも短い閾値τ₀ （ドライバーに操舵開始が早すぎると感じさせない値で、例えば２．２秒）未満になると、ステップＳ７３以降の操舵開始処理に移行し、先ずステップＳ７３で衝突回避のための必要横移動量を算出する。この必要横移動量は、基本的に前記ステップＳ４８で算出した横偏差δｄの今回値が充てられるが、誤差を除去するために前回値を用いて平均化処理を行う。続くステップＳ７４で、自車Ａｉに衝突回避運動を行わせるのに必要な基準操舵角δｈを、車速Ｖｉに基づいて算出する。
【００６２】
図１７（Ａ），（Ｂ）に示すように、前記回避運動は自車Ａｉが対向車Ａｏを回避した後に元の進路上に復帰するように行われるもので、接触時間ｔｃ（閾値τ₀ ）が経過した時点で横移動量が最終的に道路の車線を越えないこと等を考慮して例えば２ｍになるように設定する。この横移動量を接触時刻までに確保しながら、ドライバーに違和感を与えない車両挙動変化と操舵速度とが得られるように、例えば最大横加速度ＹＧを０．１５Ｇに、また操舵周期を例えば４秒（０．２５Ｈｚ）に設定する。
【００６３】
而して、基準操舵角δｈは、Ｎをステアリングギア比とし、Ｋｓをスタビリティファクターとして、次式により与えられる。
【００６４】
【数３】

【００６５】
前記（１２）式で与えられる基準操舵角δｈで自動操舵を行うことにより、自車の車速に応じてドライバーに違和感を与えない車両挙動変化と操舵速度とを保ち、且つ衝突回避に必要な横移動を行うことができるが、自車Ａｉおよび対向車Ａｏの相対角度θの方向が自車Ａｉから対向車Ａｏ側を向いていると、衝突回避を行なうために不足する場合が考えられる。そこで、前記相対角度θに基づく目標操舵角補正値δ（θ）（図１８参照）で前記（１２）式の基準操舵角δｈを補正する。
【００６６】
【数４】

【００６７】
続くステップＳ７５で，図１９に示すマップに基づいて上記基準操舵角δｈの最大値δｈｘを算出し、ステップＳ７６で基準操舵角δｈが最大値δｈｘを越えていれば、ステップＳ７７で前記最大値δｈｘで基準操舵角δｈの上限値を制限するように補正を行なう。この補正は基準操舵が最大横加速度に基づいて決められるために、自車の車速が低いときに極端に大きな操舵角になる場合があり、大きい目標操舵角δｈが採用されるのを防止することができる。
【００６８】
続くステップＳ７８で、前記ステップＳ７３で算出した必要横移動量（すなわち横偏差δｄ）と、前記ステップＳ７４〜Ｓ７７で算出した基準操舵角δｈにより発生する基準横移動量とを比較する。その結果、前者の必要横移動量（すなわち横偏差δｄ）よりも後者の基準横移動量が大きい場合には、つまり、基準操舵角δｈにより発生する横移動量が衝突回避に必要な必要横移動量よりも大きい場合には、基準操舵角δｈを減少方向に補正したものを目標操舵角として出力するか、基準操舵角δｈを目標操舵角として出力するタイミングを遅らせる。逆に、前者の必要横移動量（すなわち横偏差δｄ）よりも後者の基準横移動量が小さい場合には、つまり、基準操舵角δｈにより発生する基準横移動量が衝突回避に必要な必要横移動量よりも小さい場合には、基準操舵角δｈの補正や出力タイミングの変更は行なわない。言い換えれば、基準操舵角以上の操舵を行って車両挙動変化を大きくしたら、基準のタイミングを早めることで、ドライバーに違和感を与えることにつながる変更は行わない。
【００６９】
図２１に示すように、自車Ａｉの車速Ｖｉと、自車Ａｉおよび対向車Ａｏの相対速度Ｖｓとをパラメータとするマップにおいて、車速Ｖｉおよび相対速度Ｖｓが小さい領域では前記基準操舵角δｈの抑制（減少）制御が選択され、車速Ｖｉおよび相対速度Ｖｓが大きい領域では前記基準操舵角δｈの出力タイミングを遅らせるタイミングディレー制御が選択される。これにより、操舵角が大きくなる低車速時に基準操舵角δｈの操舵角抑制制御が選択され、操舵角が小さくなる高車速時にタイミングディレー制御が選択されることになる。
【００７０】
而して、ステップＳ７８で基準操舵角δｈの抑制制御が選択されると、ステップＳ７９で、前記基準操舵角δｈを減少方向に補正したものを目標操舵角として出力する。そしてステップＳ８３で、対向車Ａｏとの衝突を回避すべく、前記目標操舵角に応じて操舵装置１１のアクチュエータ１７の駆動を制御する。すなわち、図２０に示すように、目標操舵角およびステアリング装置１１の実操舵角の偏差が入力されたＰＩコントローラは、前記偏差をゼロに収束させるべくステアリング装置１１のアクチュエータ１７をフィードバック制御する。
【００７１】
一方、前記ステップＳ７８でタイミングディレー制御が選択されると、ステップＳ８０で基準操舵角δｈを目標操舵角として出力するタイミングを遅らせ、その分だけ操舵周期が早められる。ステップＳ８０で目標操舵角がタイミングと操舵周期とを補正されて出力されると、続くステップＳ８１で衝突の可能性を再確認する。この衝突再確認は、図９のフローチャートに基づいて最新のデータにより行なわれるもので、その結果、衝突の可能性が有ると判定されると、ステップＳ８２で操舵開始のタイミングを判定する。そして操舵開始時刻に達するまでの間は前記衝突再確認を繰り返し、操舵開始時刻に達したときに依然として衝突可能性が有ると判定されていれば、ステップＳ８２で目標操舵角を出力して自動操舵を開始する。
【００７２】
図２２は、操舵角抑制制御の一例を示すもので、破線は基準操舵角δｈをそのまま出力する場合、実線は操舵角抑制制御を行なう場合に対応している。図２２（Ａ）において、縦軸の下側ほど自車Ａｉの対向車Ａｏの車線側への逸脱の程度が大きいことを示している。操舵角抑制制御を行なう場合は行なわない場合に比べて、制御開始初期の自車Ａｉの対向車線側への逸脱が小さくなっているため、図２２（Ｂ）に示すように、操舵角抑制制御を行なう場合は行なわない場合に比べて、操舵角の振幅を小さくして自車Ａｉの横移動を小さくする。操舵角の振幅を小さくする割合は、正面衝突回避制御の操舵自体がそれほど大きな車両挙動を起こす必要がなく（車両挙動の応答が線型領域内）、また操舵角抑制制御の有無に関わらず操舵時間（操舵速度）は変わらないので、回避に必要な横移動量が基準横移動量に比べて減少した割合だけ操舵角を減少させれば、図２２（Ａ）に示すように、衝突時刻での横位置および最終的な横位置を基準操舵の場合とほぼ一致させることができる。
【００７３】
図２３は、タイミングディレー制御の一例を示すもので、破線は基準操舵角δｈをそのまま出力する場合、実線はタイミングディレー制御を行なう場合に対応している。タイミングディレー制御では、操舵角の振幅を変化させずに操舵開始タイミングを遅らせることにより横移動量を減少させる。横移動量の大小は操舵角の時間積分値（操舵角波形の内側の面積）に比例するため、前記時間積分値に基づいて操舵開始タイミングを決定することができる。操舵開始タイミングを遅らせると、それに伴って操舵速度も増加するので、横移動の開始は遅れるが横移動の応答性が前記操舵角抑制制御の場合に比べて速くなり、接触位置での横位置や最終的な横位置を基準操舵の場合とほぼ一致させることができる。
【００７４】
タイミングディレー制御を行なう場合には、その操舵時間τ₁ が、ドライバーに違和感を与えないように予め設定された基準操舵の操舵時間τ₀ よりも短くなり、ドライバーに違和感を与える可能性がある。但し、上述したようにタイミングディレー制御は操舵振幅が小さい場合に行なわれるため、単位時間当たりの操舵角変化量は小さくなり、ドライバーに与える違和感も小さくなる。またタイミングディレー制御を実行する際に、横移動量が小さいために操舵時間τ₁ が著しく小さくなる場合に備えて、最小操舵時間（例えば３秒）を設定しておき、この最小操舵時間を下回るタイミングディレー制御は行なわずに操舵角抑制による補正を加えても良い。
【００７５】
以上のように、衝突回避のための警報を行なったにも拘わらずドライバーが自発的な回避操作を実行しない場合でも、自動操舵を実行して的確な接触回避を図ることができる。また自動操舵の操舵角や操舵タイミングがドライバーに違和感を与えないように制御されるので、自動操舵とドライバーの運転操作との干渉を最小限に抑えることができる。
【００７６】
また自動操舵の開始がドライバーにとって早すぎると感じられるような場合に、タイミングディレーを行なうことによりドライバーが受ける違和感を解消することができる。しかもタイミングディレーを実行している間に衝突の可能性が繰り返し判定されるので、誤判定を防止するとともに不要な自動操舵が実行されるのを回避することができる。
【００７７】
図２１に示した操舵角抑制とタイミングディレーとの選択マップは、横軸に自車の車速をとり、縦軸に相対速度をとっているが、横軸を回避の目標操舵角とし、縦軸を回避時の相対距離とすることもできる。つまり回避の操舵角が大きいときは操舵角抑制を行って、操舵角の変化が大きいこと、および車両挙動の変化が大きいことによってドライバーに違和感を与えるのを更に防止し、また相対距離が大きいときにはタイミングディレーを行って、回避操舵が始まった時点で相対距離が大きいことによる（相対距離が大きい時点で回避の操舵が始まってしまい早すぎるという）違和感をドライバーに与えるのを防止することができる。
【００７８】
尚、ドライバーに違和感を与えない範囲でタイミングディレー制御を実行する機会を広げても良く、またタイミングディレー制御および操舵角抑制制御を別個に実行する代わりに、マップで予め設定された状況に応じて両制御を併用しても良い。
【００７９】
以上、本発明の実施例を詳述したが、本発明はその要旨を逸脱しない範囲で種々の設計変更を行うことが可能である。
【００８０】
【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、基準操舵量設定手段で、操舵により生じる自車の車両挙動変化に基づいて基準操舵量を設定するとともに、必要横移動量算出手段で、自車の適正進路および接触位置間の横偏差に基づいて決定される接触回避のための必要横移動量を算出する。そして操舵量出力手段で、前記基準操舵量設定手段で設定した基準操舵量による基準横移動量を前記必要横移動量算出手段で算出した必要横移動量と比較し、その比較結果に基づいて操舵制御手段に目標操舵量を出力するので、過剰な目標操舵量が出力されて必要横移動量よりも大きい横移動量が発生したり、目標操舵量が早く出力され過ぎたりするのを防止することができる。その結果、過剰な目標操舵量に基づく自動操舵が行なわれるのが回避され、自動操舵とドライバーの自発的な衝突回避操作との干渉を最小限に抑えることができる。
【００８１】
また請求項２に記載された発明によれば、必要横移動量算出手段で算出した必要横移動量が、基準操舵量設定手段で設定した基準操舵量に対応する基準横移動量よりも小さいときに、前記基準操舵量を減少方向に補正するので、自動操舵によって生じる車両挙動変化がドライバーに与える違和感を一層効果的に防止することができる。
【００８２】
また請求項３に記載された発明によれば、必要横移動量算出手段で算出した必要横移動量が、基準操舵量設定手段で設定した基準操舵量に対応する基準横移動量よりも小さいときに自動操舵の開始を遅らせることで、操舵の開始が早過ぎるという違和感をドライバーに与えるのを一層効果的に回避することができる。
【００８３】
また請求項４に記載された発明によれば、必要横移動量算出手段で算出した必要横移動量が、基準操舵量設定手段で設定した基準操舵量に対応する基準横移動量よりも小さいときに、相対速度または車速に基づいて前記基準操舵量を減少方向に補正するか、前記基準操舵量に基づく操舵を開始する時期を遅らせるので、自動操舵が強すぎたり自動操舵の開始が早すぎたりしてドライバーの自発的な衝突回避操作と干渉するのを防止することができる。
【００８４】
また請求項５に記載された発明によれば、自車と対向車との相対距離に基づいて基準操舵量を減少方向に補正するか、基準操舵量に基づく操舵を開始する時期を遅らせるかを選択するので、ドライバーに違和感を与えずにより小さな車両挙動変化で対向車を回避することができ、あるいはドライバーに違和感を与えずに適切なタイミングで対向車を回避することができる。
【００８５】
また請求項６に記載された発明によれば、操舵制御手段の操舵により生じる自車の車両挙動変化に基づいて設定される操舵量および自車の車速に基づいて予め設定される操舵量の何れか小さい方を基準操舵量として設定するので、ドライバーに違和感を与えるような過剰な操舵や車両挙動変化が発生するのを防止することができる。
【００８６】
また請求項７に記載された発明によれば、操舵を開始する時期を遅らせた場合に、それを補償すべく操舵速度を増加させるので、操舵の開始時期を遅らせても過不足のない横移動量を確保することができる。
【図面の簡単な説明】
【図１】 走行安全装置を備えた車両の全体構成図
【図２】 走行安全装置のブロック図
【図３】 操舵装置の斜視図
【図４】 電子制御ユニットの機能の説明図
【図５】 電子制御ユニットの回路構成を示すブロック図
【図６】 メインルーチンのフローチャート
【図７】 正面衝突回避制御ルーチンのフローチャート
【図８】 旋回時衝突回避制御ルーチンのフローチャート
【図９】 正面衝突判断ルーチンのフローチャート
【図１０】 警報制御ルーチンのフローチャート
【図１１】 回避操舵制御ルーチンのフローチャート
【図１２】 旋回時衝突回避制御の内容を示す図
【図１３】 横偏差δｄの算出手法の説明図（衝突が発生する場合）
【図１４】 横偏差δｄの算出手法の説明図（自車が対向車の左側を通過する場合）
【図１５】 横偏差δｄの算出手法の説明図（自車が対向車の右側を通過する場合）
【図１６】 横偏差δｄの補正係数を検索するマップ
【図１７】 衝突回避のための基準操舵角の算出手法の説明図
【図１８】 目標操舵角補正値δ（θ）を検索するマップ
【図１９】 最大操舵角を検索するマップ
【図２０】 アクチュエータの制御系のブロック図
【図２１】 操舵角の抑制制御およびタイミングディレー制御の選択基準の説明図
【図２２】 操舵角の抑制制御の説明図
【図２３】 操舵角のタイミングディレー制御の説明図
【符号の説明】
Ａｉ 自車
Ａｏ 対向車
ｄａ 適正横距離
Ｌ 相対距離
Ｍ１ 相対関係算出手段
Ｍ２ 適正進路設定手段
Ｍ３ 接触位置予測手段
Ｍ４ 接触可能性判定手段
Ｍ５ 操舵制御手段
Ｍ６ 基準操舵量設定手段
Ｍ７ 必要横移動量算出手段
Ｍ８ 操舵量出力手段
Ｐ 接触予測位置
Ｒ 適正進路
Ｓ₅ 車速センサ（車速検出手段）
Ｖｉ 自車の車速
Ｖｓ 相対速度
δｄ 適正横距離
δｈ 基準操舵角（基準操舵量）
θ 相対角度（相対位置）
３ レーダー装置（物体検出手段）
１１ 操舵装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle travel safety device that prevents an own vehicle from coming into contact with an oncoming vehicle using an object detection means such as a radar device.
[0002]
[Prior art]
Such a vehicle safety device is already known from JP-A-7-14100.
What is described in the above publication is that if there is a possibility that the vehicle will enter the oncoming lane and collide with the oncoming vehicle, a warning will be issued to prompt the driver to perform a collision avoidance operation, It automatically brakes to avoid collisions with oncoming vehicles.
[0003]
[Problems to be solved by the invention]
By the way, since the above-mentioned conventional one does not automatically steer the steering device of the own vehicle in order to avoid a collision with the oncoming vehicle, the case where the driver does not voluntarily perform the steering to avoid the collision or the oncoming vehicle When the vehicle does not perform the collision avoidance operation, it is conceivable that the collision cannot be avoided even if the vehicle stops by automatic braking. Therefore, it is conceivable to automatically steer the steering device of the own vehicle in order to avoid the collision, but if the start time of the automatic steering is advanced or the steering amount of the automatic steering is increased in order to enhance the collision avoidance effect May interfere with the driver's spontaneous collision avoidance operation.
[0004]
The present invention has been made in view of the above-described circumstances, and automatically steers a steering device in order to avoid contact with an oncoming vehicle. The objective is to minimize interference with the operation.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 includes an object detection means for detecting an object existing in the traveling direction of the own vehicle, a vehicle speed detection means for detecting the vehicle speed of the own vehicle, and an object detection means. Relative relationship calculating means for determining the oncoming vehicle based on the detection result by the vehicle speed and the vehicle speed of the own vehicle detected by the vehicle speed detecting means, and calculating the relative relationship of the relative position, relative distance and relative speed between the own vehicle and the oncoming vehicle And an appropriate route for setting an appropriate route for the own vehicle to properly pass an oncoming vehicle when the own vehicle is traveling on a straight road based on the relative position, the relative distance, and a preset appropriate lateral distance. A contact that predicts a contact position at which the vehicle contacts the oncoming vehicle at the contact time when the vehicle contacts the oncoming vehicle based on the relative position, the relative distance, the relative speed, and the vehicle speed of the own vehicle. Place It is determined that there is a possibility of contact by the predicting means, the contact possibility determining means for comparing the contact position with the appropriate route and determining the contact possibility between the host vehicle and the oncoming vehicle, and the contact possibility determining means. Steering control means for automatically steering the steering device of the own vehicle to avoid contact when the vehicle is driven, reference steering amount setting means for setting a reference steering amount based on a change in vehicle behavior of the own vehicle caused by steering, The required lateral movement amount calculating means for calculating the necessary lateral movement amount for avoiding the contact determined based on the lateral deviation between the appropriate course and the contact position, and the lateral movement by the reference steering amount set by the reference steering amount setting means. Steering amount output means for outputting a target steering amount to the steering control means based on the result of comparing the amount with the required lateral movement amount calculated by the required lateral movement amount calculation means.
[0006]
According to the above configuration, the reference steering amount setting means sets the reference steering amount based on the vehicle behavior change of the host vehicle caused by the steering, and the necessary lateral movement amount calculating means determines the distance between the appropriate course and the contact position of the own vehicle. Necessary lateral movement amount for avoiding contact determined based on the lateral deviation of is calculated. The steering amount output means compares the reference lateral movement amount based on the reference steering amount set by the reference steering amount setting means with the required lateral movement amount calculated by the required lateral movement amount calculation means, and steers based on the comparison result. Since the target steering amount is output to the control means, it is possible to prevent an excessive target steering amount from being output and a lateral movement amount larger than the required lateral movement amount from being generated or the target steering amount from being output too quickly. Can do. As a result, the automatic steering based on the excessive target steering amount is avoided, and the interference between the automatic steering and the driver's spontaneous collision avoidance operation can be minimized.
[0007]
According to a second aspect of the present invention, in addition to the configuration of the first aspect, the steering amount output means reduces the reference steering amount when the required lateral movement amount is smaller than the reference lateral movement amount. It is characterized by correcting to.
[0008]
According to the above configuration, when the required lateral movement amount calculated by the required lateral movement amount calculation unit is smaller than the reference lateral movement amount corresponding to the reference steering amount set by the reference steering amount setting unit, the reference steering amount is set. Since the correction is made in the decreasing direction, it is possible to more effectively prevent the uncomfortable feeling given to the driver by the change in the vehicle behavior caused by the automatic steering.
[0009]
According to a third aspect of the present invention, in addition to the configuration of the first or second aspect, the steering amount output means sets the reference steering amount when the required lateral movement amount is smaller than the reference lateral movement amount. It is characterized by delaying the timing of starting the steering based on.
[0010]
According to the above configuration, the start of automatic steering is delayed when the required lateral movement amount calculated by the required lateral movement amount calculation unit is smaller than the reference lateral movement amount corresponding to the reference steering amount set by the reference steering amount setting unit. Thus, it is possible to more effectively avoid giving the driver the uncomfortable feeling that the steering starts too early.
[0011]
The invention described in claim 4, in addition to any one of the claims 1 to 3, the steering amount output unit, when the required amount of lateral movement is less than the reference amount of lateral movement, Based on the relative speed or the vehicle speed, it is selected whether to correct the reference steering amount in a decreasing direction or to delay the timing to start steering based on the reference steering amount.
[0012]
According to the above configuration, when the required lateral movement amount calculated by the required lateral movement amount calculation unit is smaller than the reference lateral movement amount corresponding to the reference steering amount set by the reference steering amount setting unit, the relative speed or the vehicle speed is set. Based on this, the reference steering amount is corrected in a decreasing direction, or the timing for starting the steering based on the reference steering amount is delayed, so that the automatic steering is too strong or the automatic steering starts too early, and the driver's voluntary Can be prevented from interfering with a collision avoidance operation.
[0013]
According to a fifth aspect of the present invention, in addition to any one of the first to third aspects , the steering amount output means calculates the reference steering amount based on a relative distance between the host vehicle and the oncoming vehicle. It is characterized in that it is selected whether to correct in the decreasing direction or to delay the timing for starting the steering based on the reference steering amount.
[0014]
According to the above configuration , the driver selects whether to correct the reference steering amount in the decreasing direction based on the relative distance between the host vehicle and the oncoming vehicle or to delay the timing for starting the steering based on the reference steering amount. The oncoming vehicle can be avoided with a small change in vehicle behavior without giving the vehicle, or the oncoming vehicle can be avoided at an appropriate timing without giving the driver a sense of incongruity.
[0015]
According to a sixth aspect of the present invention, in addition to the configuration of any of the first to fifth aspects, the reference steering amount setting means is set based on a change in vehicle behavior of the host vehicle caused by steering of the steering control means. And a steering amount set in advance based on the vehicle speed of the host vehicle, and the smaller one is set as a reference steering amount.
[0016]
According to the above configuration, the smaller one of the steering amount set based on the vehicle behavior change of the host vehicle caused by the steering control means and the steering amount set in advance based on the vehicle speed of the host vehicle is set as the reference steering amount. Therefore, it is possible to prevent an excessive steering or a change in vehicle behavior that may cause the driver to feel uncomfortable.
[0017]
According to a seventh aspect of the present invention, in addition to the configuration of any one of the first, fourth, and fifth aspects, when the steering start timing is delayed by the steering amount output means, the steering control means The steering speed is increased so that the reference lateral movement amount based on the reference steering amount set by the setting means can be secured.
[0018]
According to the above configuration, when the timing for starting the steering is delayed, the steering speed is increased so as to compensate for this, so that a sufficient amount of lateral movement can be ensured even if the steering start timing is delayed. .
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
1 to 23 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram of a vehicle equipped with a travel safety device, FIG. 2 is a block diagram of the travel safety device, and FIG. 4 is an explanatory diagram of functions of the electronic control unit, FIG. 5 is a block diagram showing a circuit configuration of the electronic control unit, FIG. 6 is a flowchart of a main routine, FIG. 7 is a flowchart of a frontal collision avoidance control routine, and FIG. Is a flowchart of a collision avoidance control routine during turning, FIG. 9 is a flowchart of a front collision determination routine, FIG. 10 is a flowchart of an alarm control routine, FIG. 11 is a flowchart of an avoidance steering control routine, and FIG. FIG. 13 is an explanatory diagram of a method for calculating the lateral deviation δd (when a collision occurs), and FIG. 14 is an explanatory diagram of a method for calculating the lateral deviation δd (the vehicle is an oncoming vehicle). FIG. 15 is an explanatory diagram of a method for calculating the lateral deviation δd (when the vehicle passes the right side of the oncoming vehicle), FIG. 16 is a map for searching for a correction coefficient for the lateral deviation δd, and FIG. FIG. 18 is a diagram for searching for a steering angle correction value δ (θ), FIG. 19 is a map for searching for a maximum steering angle, and FIG. 20 is a control system for an actuator. FIG. 21 is an explanatory diagram of selection criteria for steering angle suppression control and timing delay control, FIG. 22 is an explanatory diagram of steering angle suppression control, and FIG. 23 is an explanatory diagram of steering angle timing delay control.
[0020]
As shown in FIGS. 1 and 2, a vehicle including left and right front wheels Wf, Wf and left and right rear wheels Wr, Wr includes a steering wheel 1 for steering left and right front wheels Wf, Wf, And an electric power steering device 2 that generates a steering force for assisting the driver to operate the steering wheel 1 and a steering force for avoiding a collision. The electronic control unit U that controls the operation of the electric power steering device 2 is input to the radar device 3 as an object detection means, a steering angle sensor S ₁ that detects the steering angle of the steering wheel 1, and the steering wheel 1. Steering torque sensor S ₂ for detecting steering torque, lateral acceleration sensor S ₃ for detecting lateral acceleration of the vehicle body, own vehicle yaw rate sensor S ₄ for detecting the yaw rate of the vehicle body, and rotation of each wheel Wf, Wf; Wr, Wr A signal from a vehicle speed sensor S ₅ that detects the number is input. The electronic control unit U controls the operation of the electric power steering device 2 on the basis of signals from the radar device 3 and the sensors S _{1 to} S ₅ ... And an alarm 4 comprising a liquid crystal display and a buzzer or lamp. The operation of the device 5 is controlled.
[0021]
The radar apparatus 3 transmits an electromagnetic wave toward a predetermined range in the left-right direction in front of the host vehicle, and receives a reflected wave in which the electromagnetic wave is reflected by the object, whereby the relative distance between the host vehicle and the object, the host vehicle and the object The relative speed and the direction of the object are detected. In this embodiment, a millimeter wave radar that can detect the relative relationship between the vehicle and the object by one transmission and reception is used.
[0022]
FIG. 3 shows the structure of the steering device 11. The rotation of the steering wheel 1 is transmitted to the rack 15 via the steering shaft 12, the connecting shaft 13 and the pinion 14, and the reciprocating motion of the rack 15 is 16 is transmitted to the left and right front wheels Wf, Wf. The electric power steering device 2 provided in the steering device 11 includes a drive gear 18 provided on the output shaft of the actuator 17, a driven gear 19 that meshes with the drive gear 18, and a screw shaft 20 that is integral with the driven gear 19. And a nut 21 which meshes with the screw shaft 20 and is connected to the rack 15. Therefore, when the actuator 17 is driven, the driving force is transmitted to the left and right front wheels Wf and Wf via the drive gear 18, the driven gear 19, the screw shaft 20, the nut 21, the rack 15, and the left and right tie rods 16 and 16. Can do.
[0023]
As shown in FIG. 4, the electronic control unit U includes electric power steering control means 22, front collision avoidance control means 23, switching means 24, and output current determination means 25. Normally, the switching means 24 is connected to the electric power steering control means 22 side, and the electric power steering device 2 exhibits a normal power steering function. In other words, the output current determining means 25 causes the actuator 17 so that the steering torque calculated based on the output of the steering torque sensor S ₂ becomes a predetermined value corresponding to the vehicle speed calculated based on the output of the vehicle speed sensor S ₅ . Is output to the actuator 17 via the drive circuit 26, so that the operation of the steering wheel 1 by the driver is assisted. On the other hand, when there is a possibility that the host vehicle collides with the oncoming vehicle, the switching means 24 is connected to the front collision avoidance control means 23 side, and the front collision avoidance control means 23 controls the driving of the actuator 17, Automatic steering is performed to avoid a frontal collision with an oncoming vehicle. The details of this automatic steering will be described later.
[0024]
Next, the configuration of the front collision avoidance control means 23 and the outline of its function will be described based on FIG.
[0025]
The front collision avoidance control unit 23 includes a relative relationship calculation unit M1, an appropriate course setting unit M2, a contact position prediction unit M3, a contact possibility determination unit M4, a steering control unit M5, and a reference steering amount setting unit M6. The required lateral movement amount calculation means M7 and the steering amount output means M8 are included.
[0026]
Based on the outputs of the object detection means (radar apparatus 3) and the vehicle speed detection means (vehicle speed sensor S ₅ ...), The relative relationship calculation means M1 is based on the relative angle (relative position) θ between the host vehicle Ai and the oncoming vehicle Ao. The distance L and the relative speed Vs are calculated. The appropriate course setting means M2 sets the original proper course R of the host vehicle Ai for the host vehicle Ai to pass the oncoming vehicle Ao appropriately. The contact position predicting means M4 predicts a contact position P at which the own vehicle Ai contacts the oncoming vehicle Ao at the contact time when the own vehicle Ai passes the oncoming vehicle Ao. The contact possibility determination means M4 compares the contact position P with the appropriate route R to determine the contact possibility of the host vehicle Ai and the oncoming vehicle Ao. When it is determined that there is a possibility that the host vehicle Ai and the oncoming vehicle Ao are in contact with each other, the steering control unit M5 automatically operates the actuator 17 of the steering device 11 to avoid contact.
[0027]
The reference steering amount setting means M6 sets the reference steering amount based on the vehicle behavior change of the host vehicle Ai caused by the steering, and the necessary lateral movement amount calculation means M7 sets the lateral deviation δd between the appropriate course R and the contact position P. A necessary lateral movement amount for avoiding the contact determined based on the calculated value is calculated. The steering amount output means M8 outputs the target steering amount to the steering control means M5 based on the result of comparing the lateral movement amount generated by the reference steering amount and the required lateral movement amount.
[0028]
Next, the operation of the present embodiment will be described in detail with reference to the flowcharts of FIGS.
[0029]
First, in step S11 of the main routine of FIG. 6, the state of the vehicle is determined based on the outputs of the steering angle sensor S ₁ , the steering torque sensor S ₂ , the lateral acceleration sensor S ₃ , the vehicle yaw rate sensor S _{4, the} vehicle speed sensor S ₅ . To detect. In the subsequent step S12, the radar device 3 detects the state of the oncoming vehicle. In addition to the oncoming vehicle, the radar device 3 detects a preceding vehicle, a pedestrian bridge, a sign, a cat's eye, and the like, but can distinguish the oncoming vehicle from other objects based on the relative speed with the own vehicle. In subsequent step S13, the state of the own vehicle and the state of the oncoming vehicle are displayed on the display 4.
[0030]
In subsequent step S14, it is checked whether or not the front collision avoidance control is appropriately performed based on the detection results of the radar device 3 and the sensors S _{1 to} S ₅ . Frontal collision avoidance control is executed only when the driver is not driving excessively. For example, when driving at an overspeed, the system operation is stopped in step S15, and the display 4 displays that effect on the driver. To encourage proper driving. If it is detected as a result of the system check in step S14 that the driver has made a steering operation to avoid a frontal collision with an oncoming vehicle, the frontal collision avoidance control is stopped in step S16. While returning to the normal electric power steering control, the display 4 notifies the driver to that effect. Thereby, it is possible to avoid interference between the spontaneous steering operation by the driver and the automatic steering control of the frontal collision avoidance control.
[0031]
If the result of the system check in step S14 is normal, the traveling state of the host vehicle is determined in step S17. The time when the host vehicle is in a state of running close to straight and passes (collision) with the oncoming vehicle based on the detection results of the radar device 3 and the sensors S _{1 to} S ₅ ... And the position of the own vehicle and the oncoming vehicle at that time If the relationship can be accurately estimated, the process proceeds to step S18 to execute frontal collision avoidance control. On the other hand, if it is not excessive driving, but the degree of turning of the own vehicle is strong, the time when it passes (collises) with the oncoming vehicle and the positional relationship between the own vehicle and the oncoming vehicle at that time cannot be accurately estimated. The process proceeds to S19 and the collision avoidance control during turning is executed. In step S20, the actuator 17 of the electric power steering apparatus 2 is operated based on the front collision avoidance control or the turn collision avoidance control in order to avoid a collision between the host vehicle and the oncoming vehicle.
[0032]
Next, the contents of the “frontal collision avoidance control” in step S18 will be described based on the flowchart of FIG.
[0033]
First, in step S21, a collision determination parameter indicating the degree of possibility of collision between the own vehicle and the oncoming vehicle, that is, the lateral deviation between the own vehicle and the appropriate route R at the time when the own vehicle and the oncoming vehicle pass each other (or the time when the vehicle collides). δd is calculated. In step S22, the lateral deviation δd is compared with a threshold value to be described later to determine whether or not there is a collision possibility. If there is a possibility of collision and the possibility is small, the alarm device 5 in step S23. Is activated to alert the driver. If there is a possibility of collision and the possibility is high, an alarm is issued, and automatic steering for avoiding the oncoming vehicle by driving the actuator 17 is executed in step S24. Specific contents of the “collision determination” in step S22, the “warning control” in step S23, and the “avoidance steering control” in step S24 will be described in detail later based on FIG. 9, FIG. 10, and FIG. .
[0034]
Next, the contents of the “turning collision avoidance control” in step S19 will be described based on the flowchart of FIG.
[0035]
First, in step S31, the collision risk during turning is calculated. As shown in FIG. 12, the collision risk level is determined based on the difference between the turning radius of the host vehicle and the turning radius of the oncoming vehicle, and the risk level is determined to increase as the difference increases. . In step S32, alarm control and lane departure prevention control according to the collision risk are executed. When turning, it is difficult to accurately estimate the time of passing (collision) with the oncoming vehicle, and the positional relationship between the host vehicle and the oncoming vehicle at that time, so the collision avoidance control is weaker than that when driving straight ahead. .
[0036]
As shown in FIG. 12, the risk of collision at the time of turning is set to three levels of level 1, level 2 and level 3, and these levels are, for example, when the vehicle is turning to the left and the vehicle is turning right. If there is, the determination is made based on the oncoming vehicle turning radius minus the own vehicle turning radius, and if the own vehicle is turning left, the determination is made based on the own vehicle turning radius minus the oncoming vehicle turning radius. At level 1 where the degree of danger is low, only the alarm by the alarm device 4 is executed, and at level 2 where the degree of danger is medium, the alarm by the alarm device 4 and weak lane departure prevention control by the actuator 17 are executed, and level 3 where the degree of danger is high. Then, the alarm by the alarm device 4 and the strong lane departure prevention control by the actuator 17 are executed. Lane departure prevention control prevents the lane departure by driving the actuator 1 of the electric power steering device 2 to generate a steering reaction force that hinders the steering when the driver steers in a direction deviating from the lane. To do.
[0037]
Note that the alarm in the “collision avoidance control during turning” is made different from the alarm in the “frontal collision avoidance control” by changing the tone color of the buzzer and the lamp of the alarm device 5.
[0038]
Next, the content of the “collision determination” in step S22 will be described based on the flowchart of FIG. 9 and the explanatory diagrams of FIGS.
[0039]
First, to calculate the vehicle speed Vi of the vehicle Ai based on the output S ₅ ... to the vehicle speed sensor in step S41, calculates the yaw rate γi of the vehicle Ai based on the output of the vehicle yaw rate sensor S ₄ in step S42, step In step S43, the relative distance L between the host vehicle Ai and the oncoming vehicle Ao is calculated based on the output of the radar device 3. In step S44, the relative speed Vs between the host vehicle Ai and the oncoming vehicle Ao is calculated based on the output of the radar device 3. In step S45, the relative angle θ between the host vehicle Ai and the oncoming vehicle Ao is calculated based on the output of the radar device 3. In the subsequent step S46, the original proper course R of the own vehicle Ai for passing without colliding with the oncoming vehicle is set based on the appropriate lateral distance da measured from the current position of the oncoming vehicle Ao. This appropriate lateral distance da is set in advance, and its value is, for example, 3 m. In subsequent step S47, the yaw rate γo of the oncoming vehicle Ao is calculated from the vehicle speed Vi and yaw rate γi of the own vehicle Ai and the relative positional relationship of the oncoming vehicle Ao with respect to the own vehicle Ai. In step S48, a lateral deviation δd between the own vehicle Ai and the appropriate route R at a position where the own vehicle Ai passes the oncoming vehicle Ao (contact position P) is calculated. Hereinafter, the process of calculating the lateral deviation δd will be described in detail with reference to FIG.
[0040]
FIG. 13 shows a state where the host vehicle Ai erroneously enters the lane on the oncoming vehicle Ao side on the left-hand traffic road. Here, the appropriate lateral position Ai ′ is a position on the appropriate route R of the host vehicle Ai and corresponding to the lateral direction of the current position of the oncoming vehicle Ao. The appropriate lateral position Ai ′ and the oncoming vehicle Ao are Is a proper lateral distance da (for example, 3 m). L is the relative distance between the host vehicle Ai and the oncoming vehicle Ao, and is calculated based on the output of the radar device 3. θ is a relative angle between the host vehicle Ai and the oncoming vehicle Ao, and is calculated based on the output of the radar device 3. ε is an angle formed between the direction of the appropriate route R of the host vehicle Ai and the direction of the oncoming vehicle Ao, and is geometrically determined based on the relative distance L and the appropriate lateral distance da. Vi is the vehicle speed of the host vehicle Ai, and is calculated based on the output of the vehicle speed sensor S ₅ . Vs is a relative vehicle speed corresponding to the difference between the vehicle speed Vi of the host vehicle Ai and the vehicle speed Vo of the oncoming vehicle Ao, and is calculated based on the output of the radar device 3.
[0041]
In FIG. 13, in the hatched triangle,
X cos (θ + ε) = L sinθ (1)
And when this is solved for X,
X = L sin θ / cos (θ + ε) (2)
Is obtained. The contact time tc (elapsed time until the passing time or the collision time) measured based on the present time is obtained as a value obtained by dividing the relative distance L by the relative speed Vs.
[0042]
tc = L / Vs (3)
A distance Lc from the own vehicle Ai to the contact position P (passing position or collision position) is obtained as a product of the vehicle speed Vi and the contact time tc.
[0043]
Lc = Vi · tc = L (Vi / Vs) (4)
As is apparent from FIG. 13, from the similarity of two right triangles sharing the vertex of the angle θ + ε at the position of the vehicle Ai,
Lc ′: L = δd: da + X (5)
Further, from the relationship of Lc ′ cosε = Lc cos (θ + ε) and the equations (2), (4), and (5), the lateral deviation δd is obtained as follows.
[0044]
[Expression 1]

[0045]
Of the five variables on the right side of the equation (6), Vi can always be calculated, and Vs, L, θ, and ε can be calculated by one transmission / reception of the radar device 3. When the oncoming vehicle Ao is determined, the lateral deviation δd can be quickly calculated. Therefore, even when the own vehicle Ai and the oncoming vehicle Ao approach each other and there is no allowance for the contact time tc, it is possible to promptly determine the possibility of contact and start the collision avoidance control.
[0046]
Thus, in step S49 of the flowchart of FIG. 9, the lateral deviation δd is compared with a preset contact determination reference value, and the lateral deviation δd is between the first contact determination reference value δdn and the second contact determination reference value δdx. If it is, that is, if δdn <δd <δdx is established, it is determined in step S50 that the own vehicle Ai may collide with the oncoming vehicle Ao (see FIG. 13). On the other hand, if δd ≦ δdn as shown in FIG. 14 or if δd ≧ δdx as shown in FIG. 15, it is determined in step S51 that there is no possibility that the host vehicle Ai collides with the oncoming vehicle Ao. The state in FIG. 15 corresponds to the case where the host vehicle Ai crosses the lane of the oncoming vehicle Ao diagonally in order to enter the branch road, for example.
[0047]
The first contact determination reference value δdn and the second contact determination reference value δdx are appropriately set according to the vehicle width of the host vehicle Ai. For example, the first contact determination reference value δdn = 1.5 m, The 2-contact determination reference value δdx = 4.5 m.
[0048]
In the above description, the yaw rate γi of the host vehicle Ai and the yaw rate γo of the oncoming vehicle Ao are not taken into account when calculating the lateral deviation δd. However, by considering these yaw rates γi and γo, more accurate collision avoidance can be achieved. Done.
[0049]
Since the lateral acceleration of Viγi occurs when the host vehicle Ai travels at the vehicle speed Vi and the yaw rate γi, the lateral movement amount yi of the host vehicle Ai is calculated by integrating this Viγi twice. Therefore, the lateral movement amount yi of the host vehicle Ai at the contact time tc = L / Vs is
yi = (Vi · γi / 2) · (L / Vs) ² (7)
Given in.
[0050]
Similarly, when the oncoming vehicle Ao travels at the vehicle speed Vo and the yaw rate γo, a lateral acceleration of Voγo occurs. Therefore, the lateral movement amount yo of the oncoming vehicle Ao is calculated by integrating this Voγo twice. Therefore, the lateral movement amount yo of the oncoming vehicle Ao at the contact time tc = L / Vs is
yo = (Vo · γo / 2) · (L / Vs) ² (8)
Given in.
[0051]
Thus, the accuracy of the lateral deviation δd is further improved by using the following equation in which the lateral deviation δd in the above equation (6) is corrected by the lateral movement amount yi of the own vehicle Ai and the lateral movement amount yo of the oncoming vehicle Ao. Can be increased.
[0052]
[Expression 2]

[0053]
If the yaw rate γo of the oncoming vehicle Ao is detected a plurality of times based on the output of the radar device 3 and the turning locus of the oncoming vehicle Ao is estimated, the turning radius and the vehicle speed Vo of the oncoming vehicle Ao Is calculated based on Therefore, the yaw rate γo of the oncoming vehicle Ao cannot be detected by a single transmission / reception of the laser device 3, and some calculation time is required to perform correction using the yaw rate γo of the oncoming vehicle Ao in equation (9). become. However, as described in step S17 of the flowchart of FIG. 6, this frontal collision avoidance control is performed when the vehicle Ai is traveling substantially straight (when traveling on a straight road), At this time, it is rare that the yaw rate γo of the oncoming vehicle Ao has a large value. Therefore, sufficient accuracy can be ensured without performing correction using the yaw rate γo of the oncoming vehicle Ao.
[0054]
By the way, instead of setting the first contact determination reference value δdn and the second contact determination reference value δdx as fixed values, the first contact determination reference value δdn and the second contact determination reference value δdx are calculated at the time when the lateral deviation δd is calculated. If correction is performed in the traveling state of the host vehicle Ai and the oncoming vehicle Ao, the frontal collision avoidance control can be performed with higher accuracy. That is, the correction of the first contact determination reference value δdn is performed using three correction coefficients k1n, k2n, and k3n.
δdn ← k1n · k2n · k3n · δdn (10)
The correction of the second contact determination reference value δdx is performed using three correction coefficients k1x, k2x, k3x,
δdx ← k1x · k2x · k3x · δdx (11)
It is done as follows.
[0055]
The correction coefficients k1n and k1x are searched based on the time (contact time tc) until the collision from the map shown in FIG. The correction coefficients k1n and k1x are held at 1 in an area where the calculation error of the lateral deviation δd is estimated to be small because the contact time tc is small. In the region where the calculation error of the lateral deviation δd is estimated to be large because the contact time tc is large, the correction coefficient k1n increases from 1 as the contact time tc increases, and the correction coefficient k1x increases the contact time tc. It decreases from 1 with it. This reduces the width between the first contact determination reference value δdn and the second contact determination reference value δdx in an area where the calculation error of the lateral deviation δd is large, thereby avoiding uncertain frontal collision avoidance control. be able to.
[0056]
The correction coefficients k2n and k2x are searched based on the relative distance L between the host vehicle Ai and the oncoming vehicle Ao from the map shown in FIG. The correction coefficients k2n and k2x are held at 1 in the region where the calculation error of the lateral deviation δd is estimated to be small because the relative distance L is small. In the region where the calculation error of the lateral deviation δd is estimated to be large because the relative distance L is large, the correction coefficient k2n increases from 1 as the relative distance L increases, and the correction coefficient k2x increases the relative distance L. It decreases from 1 with it. This reduces the width between the first contact determination reference value δdn and the second contact determination reference value δdx in an area where the calculation error of the lateral deviation δd is large, thereby avoiding uncertain frontal collision avoidance control. be able to.
[0057]
The correction coefficients k3n and k3x are retrieved from the map shown in FIG. 16C based on the yaw rate γi of the vehicle Ai. When it is estimated that the yaw rate γi of the own vehicle Ai is 0 and the calculation error of the lateral deviation δd is small, the correction coefficients k3n and k3x are set to 1. When the calculation error of the lateral deviation δd increases as the yaw rate γi of the host vehicle Ai increases, the correction coefficient k3n increases from 1 and the correction coefficient k3x decreases from 1. This reduces the width between the first contact determination reference value δdn and the second contact determination reference value δdx in an area where the calculation error of the lateral deviation δd is large, thereby avoiding uncertain frontal collision avoidance control. be able to.
[0058]
Next, the contents of the “alarm control” in step S23 will be described based on the flowchart of FIG.
[0059]
First, collision information is received in step S61. The collision information includes a contact time tc (time until a collision), traveling states of the host vehicle Ai and the oncoming vehicle Ao at the contact position P, a lateral deviation δd, and the like. In step S62, the primary alarm is determined. When the contact time tc is less than 4 seconds, for example, the alarm 5 is activated in step S63 to start the primary alarm. Subsequently, in step S64, the secondary alarm is determined. When the contact time tc is less than 3 seconds, for example, the alarm device 5 is activated in step S65 to start the secondary alarm. The primary alarm is executed when the time margin until the collision is relatively large, and the secondary alarm is performed when the time margin until the collision is relatively small, and the driver is made aware of the difference. Change the buzzer tone and lamp color as much as possible. The driver can recognize the danger of collision by an alarm from the alarm device 5 and can perform a spontaneous avoidance operation.
[0060]
Next, the contents of the “avoidance steering control” in step S24 will be described based on the flowchart of FIG.
[0061]
First, in step S71, after the collision information is received in the same manner as in step S61, the steering start is determined in the subsequent step S72, and the contact time tc is a threshold value τ ₀ shorter than the secondary alarm threshold value of 3 seconds. If it becomes less than (for example, 2.2 seconds), the steering start process after step S73 is started. First, in step S73, the necessary lateral movement amount for avoiding the collision is calculated. To do. This required lateral movement amount basically corresponds to the current value of the lateral deviation δd calculated in step S48, but an averaging process is performed using the previous value in order to remove the error. In a subsequent step S74, a reference steering angle δh necessary for causing the host vehicle Ai to perform a collision avoidance motion is calculated based on the vehicle speed Vi.
[0062]
As shown in FIGS. 17A and 17B, the avoidance movement is performed so that the host vehicle Ai returns to the original course after avoiding the oncoming vehicle Ao, and the contact time tc (threshold value τ _0). In consideration of the fact that the lateral movement amount does not eventually exceed the lane of the road at the time when) elapses, for example, it is set to 2 m. For example, the maximum lateral acceleration YG is set to 0.15 G, and the steering cycle is set to, for example, 4 seconds so that the vehicle movement change and the steering speed that do not give the driver a sense of incongruity can be obtained while securing the lateral movement amount by the contact time. (0.25 Hz).
[0063]
Thus, the reference steering angle δh is given by the following equation, where N is the steering gear ratio and Ks is the stability factor.
[0064]
[Equation 3]

[0065]
By performing automatic steering at the reference steering angle δh given by the equation (12), the vehicle behavior change and the steering speed that do not give the driver a sense of incongruity according to the vehicle speed of the host vehicle are maintained, and the sideways necessary for avoiding a collision are maintained. Although the vehicle can move, if the direction of the relative angle θ between the host vehicle Ai and the oncoming vehicle Ao faces the oncoming vehicle Ao from the host vehicle Ai, there may be a shortage in order to avoid collision. Therefore, the reference steering angle δh of the equation (12) is corrected with the target steering angle correction value δ (θ) (see FIG. 18) based on the relative angle θ.
[0066]
[Expression 4]

[0067]
In the following step S75, the maximum value δhx of the reference steering angle δh is calculated based on the map shown in FIG. 19, and if the reference steering angle δh exceeds the maximum value δhx in step S76, the maximum value δhx is determined in step S77. To correct the upper limit value of the reference steering angle δh. Since this correction is determined based on the maximum lateral acceleration, the steering angle may be extremely large when the vehicle speed is low, and a large target steering angle δh is prevented from being adopted. Can do.
[0068]
In the following step S78, the required lateral movement amount (that is, lateral deviation δd) calculated in step S73 is compared with the reference lateral movement amount generated by the reference steering angle δh calculated in steps S74 to S77. As a result, when the latter reference lateral movement amount is larger than the former required lateral movement amount (that is, lateral deviation δd), that is, the lateral movement amount generated by the reference steering angle δh is the necessary lateral movement necessary for collision avoidance. If larger than the amount, the reference steering angle δh corrected in the decreasing direction is output as the target steering angle, or the timing at which the reference steering angle δh is output as the target steering angle is delayed. On the contrary, when the latter reference lateral movement amount is smaller than the former required lateral movement amount (that is, lateral deviation δd), that is, the reference lateral movement amount generated by the reference steering angle δh is the necessary lateral movement necessary for avoiding the collision. If it is smaller than the movement amount, the reference steering angle δh is not corrected and the output timing is not changed. In other words, if the vehicle behavior change is increased by steering beyond the reference steering angle, the reference timing is advanced, and no change that leads to an uncomfortable feeling to the driver is performed.
[0069]
As shown in FIG. 21, in a map using the vehicle speed Vi of the host vehicle Ai and the relative speed Vs of the host vehicle Ai and the oncoming vehicle Ao as parameters, the reference steering angle δh is set in a region where the vehicle speed Vi and the relative speed Vs are small. The suppression (decrease) control is selected, and in the region where the vehicle speed Vi and the relative speed Vs are large, the timing delay control that delays the output timing of the reference steering angle δh is selected. As a result, the steering angle suppression control of the reference steering angle δh is selected at a low vehicle speed at which the steering angle is large, and the timing delay control is selected at a high vehicle speed at which the steering angle is small.
[0070]
Thus, when the suppression control of the reference steering angle δh is selected in step S78, a value obtained by correcting the reference steering angle δh in the decreasing direction is output as a target steering angle in step S79. In step S83, driving of the actuator 17 of the steering device 11 is controlled in accordance with the target steering angle in order to avoid a collision with the oncoming vehicle Ao. That is, as shown in FIG. 20, the PI controller to which the deviation between the target steering angle and the actual steering angle of the steering device 11 is input performs feedback control of the actuator 17 of the steering device 11 so as to converge the deviation to zero.
[0071]
On the other hand, when the timing delay control is selected in step S78, the timing for outputting the reference steering angle δh as the target steering angle is delayed in step S80, and the steering cycle is advanced accordingly. When the target steering angle is output with the timing and the steering cycle corrected in step S80, the possibility of a collision is reconfirmed in step S81. This collision reconfirmation is performed based on the latest data based on the flowchart of FIG. 9, and as a result, if it is determined that there is a possibility of collision, the timing for starting steering is determined in step S82. The collision reconfirmation is repeated until the steering start time is reached, and if it is determined that there is still a possibility of a collision when the steering start time is reached, the target steering angle is output in step S82 and automatic steering is performed. To start.
[0072]
FIG. 22 shows an example of the steering angle suppression control. The broken line corresponds to the case where the reference steering angle δh is output as it is, and the solid line corresponds to the case where the steering angle suppression control is performed. FIG. 22A shows that the lower the vertical axis, the greater the degree of departure of the oncoming vehicle Ao from the host vehicle Ai toward the lane. Compared with the case where the steering angle suppression control is not performed, the deviation of the own vehicle Ai toward the oncoming lane at the beginning of the control is smaller. Therefore, as shown in FIG. 22B, the steering angle suppression control is performed. Compared with the case where it does not, the amplitude of a steering angle is made small and lateral movement of the own vehicle Ai becomes small. The ratio of reducing the amplitude of the steering angle is such that the steering of the frontal collision avoidance control itself does not have to cause a very large vehicle behavior (the response of the vehicle behavior is in a linear region), and the steering time regardless of the presence or absence of the steering angle suppression control Since (steering speed) does not change, if the steering angle is decreased by a rate at which the lateral movement amount necessary for avoidance is reduced compared to the reference lateral movement amount, as shown in FIG. The lateral position and the final lateral position can be substantially matched with the case of the reference steering.
[0073]
FIG. 23 shows an example of timing delay control. The broken line corresponds to the case where the reference steering angle δh is output as it is, and the solid line corresponds to the case where the timing delay control is performed. In the timing delay control, the lateral movement amount is reduced by delaying the steering start timing without changing the steering angle amplitude. Since the amount of lateral movement is proportional to the time integral value of the steering angle (the area inside the steering angle waveform), the steering start timing can be determined based on the time integral value. If the steering start timing is delayed, the steering speed increases accordingly, so that the start of the lateral movement is delayed, but the response of the lateral movement is faster than in the case of the steering angle suppression control, and the lateral position at the contact position and The final lateral position can be made substantially coincident with the case of the standard steering.
[0074]
When the timing delay control is performed, the steering time τ ₁ is shorter than the reference steering time τ ₀ set in advance so as not to give the driver a sense of incongruity, which may give the driver a sense of incongruity. However, as described above, since the timing delay control is performed when the steering amplitude is small, the amount of change in the steering angle per unit time is small, and the uncomfortable feeling given to the driver is also small. In addition, when the timing delay control is executed, a minimum steering time (for example, 3 seconds) is set in preparation for a case where the steering time τ ₁ becomes remarkably small due to a small amount of lateral movement, which is below the minimum steering time. Correction by steering angle suppression may be added without performing timing delay control.
[0075]
As described above, even when the driver does not perform the spontaneous avoidance operation despite the warning for avoiding the collision, the automatic steering can be executed to accurately avoid contact. Further, since the steering angle and steering timing of the automatic steering are controlled so as not to give the driver a sense of incongruity, interference between the automatic steering and the driving operation of the driver can be minimized.
[0076]
In addition, when it is felt that the start of the automatic steering is too early for the driver, the uncomfortable feeling experienced by the driver can be eliminated by performing the timing delay. In addition, since the possibility of collision is repeatedly determined during execution of the timing delay, erroneous determination can be prevented and unnecessary automatic steering can be avoided.
[0077]
In the selection map of steering angle suppression and timing delay shown in FIG. 21, the horizontal axis represents the vehicle speed of the host vehicle and the vertical axis represents the relative speed. The horizontal axis represents the target steering angle for avoidance, and the vertical axis Can also be the relative distance when avoiding. In other words, when the steering angle for avoidance is large, the steering angle is suppressed to further prevent the driver from feeling uncomfortable due to the large change in the steering angle and the large change in the vehicle behavior, and when the relative distance is large. By performing the timing delay, it is possible to prevent the driver from feeling uncomfortable due to the fact that the relative distance is large when the avoidance steering starts (the avoidance steering starts too early when the relative distance is large).
[0078]
In addition, the opportunity to execute the timing delay control within a range that does not give the driver a sense of incongruity may be expanded, and instead of separately executing the timing delay control and the steering angle suppression control, depending on the situation set in advance on the map Both controls may be used in combination.
[0079]
As mentioned above, although the Example of this invention was explained in full detail, this invention can perform a various design change in the range which does not deviate from the summary.
[0080]
【The invention's effect】
As described above, according to the first aspect of the present invention, the reference steering amount setting means sets the reference steering amount based on the vehicle behavior change of the host vehicle caused by the steering, and the necessary lateral movement amount calculation means. Then, a necessary lateral movement amount for avoiding contact, which is determined on the basis of the proper course of the own vehicle and the lateral deviation between the contact positions, is calculated. The steering amount output means compares the reference lateral movement amount based on the reference steering amount set by the reference steering amount setting means with the required lateral movement amount calculated by the required lateral movement amount calculation means, and steers based on the comparison result. Since the target steering amount is output to the control means, it is possible to prevent an excessive target steering amount from being output and a lateral movement amount larger than the required lateral movement amount from being generated or the target steering amount from being output too quickly. Can do. As a result, the automatic steering based on the excessive target steering amount is avoided, and the interference between the automatic steering and the driver's spontaneous collision avoidance operation can be minimized.
[0081]
According to the second aspect of the present invention, when the required lateral movement amount calculated by the required lateral movement amount calculating means is smaller than the reference lateral movement amount corresponding to the reference steering amount set by the reference steering amount setting means. In addition, since the reference steering amount is corrected in the decreasing direction, it is possible to more effectively prevent a sense of discomfort given to the driver by a change in vehicle behavior caused by automatic steering.
[0082]
According to the third aspect of the present invention, when the required lateral movement amount calculated by the required lateral movement amount calculating means is smaller than the reference lateral movement amount corresponding to the reference steering amount set by the reference steering amount setting means. By delaying the start of automatic steering, it is possible to more effectively avoid giving the driver the uncomfortable feeling that the start of steering is too early.
[0083]
According to the fourth aspect of the present invention, when the necessary lateral movement amount calculated by the necessary lateral movement amount calculating means is smaller than the reference lateral movement amount corresponding to the reference steering amount set by the reference steering amount setting means. In addition, the reference steering amount is corrected in the decreasing direction based on the relative speed or the vehicle speed, or the timing for starting the steering based on the reference steering amount is delayed, so that the automatic steering is too strong or the automatic steering starts too early. Thus, interference with the driver's spontaneous collision avoidance operation can be prevented.
[0084]
According to the fifth aspect of the present invention, whether to correct the reference steering amount in the decreasing direction based on the relative distance between the host vehicle and the oncoming vehicle or to delay the timing for starting the steering based on the reference steering amount. Since the selection is made, the oncoming vehicle can be avoided with a small change in vehicle behavior without causing the driver to feel uncomfortable, or the oncoming vehicle can be avoided at an appropriate timing without causing the driver to feel uncomfortable.
[0085]
According to the sixth aspect of the present invention, any one of the steering amount set based on the vehicle behavior change of the host vehicle caused by the steering of the steering control means and the steering amount set in advance based on the vehicle speed of the host vehicle. Since the smaller one is set as the reference steering amount, it is possible to prevent an excessive steering or a change in vehicle behavior that gives a driver a sense of incongruity.
[0086]
According to the seventh aspect of the present invention, when the timing for starting the steering is delayed, the steering speed is increased to compensate for this, so that the lateral movement without excess or deficiency even if the timing for starting the steering is delayed. The amount can be secured.
[Brief description of the drawings]
1 is an overall configuration diagram of a vehicle equipped with a travel safety device. FIG. 2 is a block diagram of the travel safety device. FIG. 3 is a perspective view of a steering device. FIG. 4 is an explanatory diagram of functions of an electronic control unit. FIG. 6 is a block diagram showing the circuit configuration of the electronic control unit. FIG. 6 is a flowchart of a main routine. FIG. 7 is a flowchart of a front collision avoidance control routine. Flowchart [FIG. 10] Flowchart of alarm control routine [FIG. 11] Flowchart of avoidance steering control routine [FIG. 12] Diagram showing contents of collision avoidance control during turning [FIG. 13] Explanatory diagram of calculation method of lateral deviation δd If it occurs)
FIG. 14 is an explanatory diagram of a method for calculating the lateral deviation δd (when the vehicle passes the left side of the oncoming vehicle)
FIG. 15 is an explanatory diagram of a method for calculating the lateral deviation δd (when the vehicle passes the right side of the oncoming vehicle)
FIG. 16 is a map for searching for a correction coefficient for the lateral deviation δd. FIG. 17 is an explanatory diagram of a method for calculating a reference steering angle for collision avoidance. FIG. 18 is a map for searching for a target steering angle correction value δ (θ). FIG. 19 is a map for searching for the maximum steering angle. FIG. 20 is a block diagram of an actuator control system. FIG. 21 is an explanatory diagram of selection criteria for steering angle suppression control and timing delay control. Explanatory drawing [Fig. 23] Explanatory diagram of steering angle timing delay control [Explanation of symbols]
Ai Own vehicle Ao Oncoming vehicle da Appropriate lateral distance L Relative distance M1 Relative relationship calculation means M2 Appropriate course setting means M3 Contact position prediction means M4 Contact possibility determination means M5 Steering control means M6 Reference steering amount setting means M7 Necessary lateral movement amount calculation Means M8 Steering amount output means P Predicted contact position R Proper path S ₅ Vehicle speed sensor (vehicle speed detection means)
Vi Vehicle speed Vs Relative speed δd Proper lateral distance δh Reference steering angle (reference steering amount)
θ Relative angle (relative position)
3 Radar device (object detection means)
11 Steering device

Claims (7)

Object detection means (3) for detecting an object present in the traveling direction of the host vehicle (Ai);
Vehicle speed detection means (S ₅ ) for detecting the vehicle speed (Vi) of the host vehicle (Ai);
The oncoming vehicle (Ao) is discriminated based on the detection result by the object detection means (3) and the vehicle speed (Vi) of the own vehicle (Ai) detected by the vehicle speed detection means (S ₅ ), and is opposed to the own vehicle (Ai). A relative relationship calculating means (M1) for calculating a relative relationship consisting of a relative position (θ), a relative distance (L) and a relative speed (Vs) with respect to the car (Ao);
Based on the relative position (θ), the relative distance (L), and the preset appropriate lateral distance (da), when the host vehicle (Ai) is traveling on a straight road, the vehicle is properly matched with the oncoming vehicle (Ao). An appropriate route setting means (M2) for setting an appropriate route (R) of the own vehicle (Ai) for passing each other;
The contact position (P) where the host vehicle (Ai) contacts the oncoming vehicle (Ao) at the contact time when the host vehicle (Ai) contacts the oncoming vehicle (Ao) is defined as the relative position (θ) and the relative distance (L ), Contact position predicting means (M3) for predicting based on the relative speed (Vs) and the vehicle speed (Vi) of the host vehicle (Ai);
Contact possibility determination means (M4) for comparing the contact position (P) with the appropriate course (R) and determining the contact possibility between the host vehicle (Ai) and the oncoming vehicle (Ao);
Steering control means (M5) for automatically steering the steering device (11) of the host vehicle (Ai) to avoid contact when it is determined by the contact possibility determination means (M4) that there is a possibility of contact; ,
Reference steering amount setting means (M6) for setting a reference steering amount (δh) based on a change in vehicle behavior of the host vehicle (Ai) caused by steering;
A required lateral movement amount calculating means (M7) for calculating a necessary lateral movement amount for avoiding contact determined based on a lateral deviation (δd) between the appropriate path (R) and the contact position (P);
Based on the result of comparing the reference lateral movement amount based on the reference steering amount (δh) set by the reference steering amount setting means (M6) with the required lateral movement amount calculated by the required lateral movement amount calculation means (M7), the steering control means Steering amount output means (M8) for outputting the target steering amount to (M5),
A vehicle travel safety device comprising:   The steering amount output means (M8) corrects the reference steering amount (δh) in a decreasing direction when the required lateral movement amount is smaller than the reference lateral movement amount. Vehicle travel safety device.   The steering amount output means (M8) delays the timing for starting steering based on the reference steering amount (δh) when the required lateral movement amount is smaller than the reference lateral movement amount. The travel safety device for a vehicle according to 1 or 2. The steering amount output means (M8) decreases the reference steering amount (δh) based on the relative speed (Vs) or the vehicle speed (Vi) when the required lateral movement amount is smaller than the reference lateral movement amount. in either corrected, and selects the delay or timing of starting the steering operation based on the reference steering amount (.delta.h), travel safety device for a vehicle according to any one of claims 1 to 3. The steering amount output means (M8) corrects the reference steering amount (δh) in the decreasing direction based on the relative distance (L) between the host vehicle (Ai) and the oncoming vehicle (Ao), or the reference steering amount ( The vehicle travel safety device according to any one of claims 1 to 3, wherein whether to start the steering based on δh) is delayed. The reference steering amount setting means (M6) is preset based on the steering amount set based on the vehicle behavior change of the own vehicle caused by the steering of the steering control means (M5) and the vehicle speed (Vi) of the own vehicle (Ai). The travel safety device for a vehicle according to any one of claims 1 to 5, wherein a set steering amount is compared and the smaller one is set as a reference steering amount (δh). When the timing for starting the steering is delayed by the steering amount output means (M8), the steering control means (M5) can secure the lateral movement amount by the reference steering amount (δh) set by the reference steering amount setting means (M6). characterized in that to increase the steering speed as the traveling safety device for a vehicle according to any one of claims 1, 4 and 5.

Images