JP3901020B2 - Inter-vehicle distance control device - Google Patents

Description

【００２０】
つまり、上記（３）式により演算される目標車間距離Ｌ_T と目標相対速度ΔＶ_T は、実車間距離Ｌが目標応答特性を経て車間距離指令値Ｌ^* に収束するように、車間距離と相対速度の時間的推移を規定した最終車間距離指令値である。
この（３）式を展開してラプラス変換すると下記（４）式のように表すことができる。
【００２１】
【数２】

【００２２】
この（４）式は車間距離指令値Ｌ^* に対する目標車間距離Ｌ_T の伝達関数であり、二次式で表される。この実施の形態では、車間距離制御系において、実車間距離Ｌが（４）式で表される目標車間距離Ｌ_T（最終車間距離指令値）となるようにフィードバック制御を行う。上述したように、車間距離制御系の減衰係数ζ_T と固有振動数ω_T に、車間距離偏差ΔＬと相対速度ΔＶとに応じた目標車間距離制御応答が得られる値を設定したので、種々の追従シーンにおいて望ましい車間距離制御応答を実現できる。
【００２３】
目標車間距離制御応答としては、割込シーンや追い抜きシーンなどにおいて、先行車との車間距離が指令値を下回っているときでも、先行車との相対速度が小さい場合は急な減速を行わず、実車間距離が指令値へゆっくりと収束するような応答が望ましい。また、接近シーンなどにおいて、相対速度が大きいときでも車間距離が長い場合は急な減速を行わず、実車間距離が指令値へゆっくり収束するような応答が望ましい。このような追従シーンでは、実車間距離が指令値をオーバーシュート又はアンダーシュートしてから収束するような二次の応答特性となり、そのような応答は前記（３）式及び（４）式に示す二次のフィルタにより実現することができる。
【００２４】
車速指令値演算部３４は、所定の定数ｆ_V 及びｆ_L を用いて下記（５）式に従って演算することにより車速指令値Ｖ^*を演算する。

この（５）式において、ｆ_V は目標相対速度偏差（目標相対速度ΔＶ_T (t) と相対速度検出値ΔＶ(t)との差）｛ΔＶ_T(t)−ΔＶ(t) ｝に乗ずる定数、ｆ_L は目標車間距離偏差（目標車間距離Ｌ_T (t) と車間距離検出値Ｌ(t) との差）｛Ｌ_T (t)−Ｌ(t) ｝に乗ずる定数である。
【００２５】
このように実車間距離Ｌが目標車間距離応答特性を示す目標車間距離Ｌ_T に収束するようにフィードバック制御するフィードバック制御系では、応答性を挙げるためには車間距離制御系の制御ゲインを大きくし制御時定数を短くしなければならず、そうすると安定性が犠牲となるというトレードオフの関係がある。
そこで、車間距離フィードバック制御系にフィードフォワードループを加え、車間距離指令値Ｌ^* から目標車間距離応答を得るための補償車速指令値Ｖ_C を求め、この補償車速指令値Ｖ_C により車間距離制御系で得られた車速指令値Ｖ^*を補正する。したがって、車間距離制御系において安定性を損なわずに応答性を向上させるために、先行車追従コントローラ３に前置補償車速指令値演算部３５と、補正車速指令値演算部３６とが付加されている。また、補正車速指令値演算部３６で算出される補正車速指令値の変化率を制限するための補正車速指令値変化率制限部３７も付加されている。
【００２６】
前置補償車速指令値演算部３５は、基本車間距離指令値Ｌ^* を下記（６）式で表されるフィルタを通して補償車速指令値Ｖ_C を演算する。
【００２７】
【数３】

【００２８】
この（６）式のフィルタは、車速指令値Ｖ^*から実車間距離Ｌまでの伝達関数の逆系と、前記（４）式で表される目標車間距離制御応答特性との積で表される。ここで、車速指令値Ｖ^*から実車間距離Ｌまでの伝達関数は、車速指令値Ｖ^*を入力とし実車速Ｖを出力とする前記（１）式で表される車速制御系の伝達関数Ｇｖ(s)と、実車速Ｖと先行車車速Ｖｔとの差、つまり相対速度ΔＶを積分して実車間距離Ｌを得るための積分器との積で表される。なお、前記（６）式により補償車速指令値Ｖ_C を演算するときの初期値は、先行車両を認識した直後の車間距離Ｌ₀ と相対速度ΔＶ₀ とする。
【００２９】
補正車速指令値演算部３６は、下記（７）式のように、車間距離制御系で演算した車速指令値Ｖ^*から補償車速指令値Ｖ_C を減算した値（Ｖ^*−Ｖ_C ）、又は乗員が設定した車速設定値Ｖ_SET の値の小さい方を補正車速指令値Ｖ^*'として補正車速指令値変化率制限部３７へ出力する。なお、車間距離センサ1により先行車を捕捉できない場合は、乗員が目標車速として設定した車速設定値Ｖ_SETが、そのまま補正車速指令値Ｖ^*'となる。
【００３０】
Ｖ^*'＝ min（Ｖ^*−Ｖ_C 、Ｖ_SET ） ・・・・・・・・・（７）
補正車速指令値変化率制限部３７は、上述した補正車速指令値Ｖ^*'に変化率制限を施し、最終的な補正車速指令値Ｖ^*''を演算し、前述した車速制御部４へ出力する。
この補正車速指令値変化率制限部３７では、図２に示す車速指令値変化率制限処理を所定時間（例えば１０msec）毎に実行する。なお、_(n) は今回の処理で算出された値を、_(n-1) は前回の処理で算出された値を夫々表しており、特に _(n)又は _(n-1) と明記されていない変数については、今回の値を表している。
【００３１】
この指令値変化率制限処理は、先ず、ステップＳ１で、車間距離センサ１により捕捉可能な先行車が有るか否かを判定し、先行車がいなければ、ステップＳ２に移行する。
このステップＳ２では、先行車の捕捉状況を表す捕捉フラグＦ_C が先行車を捕捉していない状況を表す“０”にリセットされているか否かを判定する。この判定結果が捕捉フラグＦ_C＝１であるときは、前回の処理段階では先行車を捕捉していたものの、その先行車を見失ったと判断してステップＳ３に移行する。
【００３２】
このステップＳ３では、先行車を見失った時点からカウントを開始するタイマＴを“０”にクリアし、続くステップＳ４で捕捉フラグＦ_Cを“０”にリセットしてからステップＳ５に移行する。
このステップＳ５では、先行車を見失った時点の車速Ｖを維持するために、前回の処理で算出された最終補正車速指令値Ｖ^*''_(n-1) を、再び今回の最終補正車速指令値Ｖ^*''_(n) として車速制御部４へ出力してから、前記ステップＳ１に戻る。
【００３３】
一方、前記ステップＳ２の判定結果が捕捉フラグＦ_C＝０であるときは、先行車を見失った状態を継続しているものと判断してステップＳ６に移行し、前回の処理段階でカウントされたタイマＴ_(n-1) に“１”をインクリメントしてからステップＳ７に移行する。
このステップＳ７では、先行車を見失ってからカウントを開始したタイマＴが所定値Ｔ₁以上であるか否かを判定している。この判定結果がＴ＜Ｔ₁であるときは、先行車の見失いが一時的なものである可能性があると判断して前記ステップＳ５に移行する。一方、判定結果がＴ≧Ｔ₁であるときは、追従走行に適当な先行車を失った可能性があると判断してステップＳ８に移行する。
このステップＳ８では、補正車速指令値Ｖ^*'の変化率を制限するための車速変化率制限値Ｖ^* _RATE の設定方法を切換える切換フラグＦ_S を“０”にリセットしてから、後述するステップＳ１５に移行する。
【００３４】
一方、前記ステップＳ１で、先行車有りと判定されるときには、ステップＳ９に移行して、捕捉フラグＦ_C が“１”にセットされているか否かを判定する。この判定結果が捕捉フラグＦ_C＝０であるときは、先行車の捕捉を開始したと判断して、ステップＳ１０で捕捉フラグＦ_C を“１”にセットしてからステップＳ１１に移行する。
【００３５】
このステップＳ１１では、先行車を捕捉した直後の相対車速ΔＶ₀ 及び車間距離偏差ΔＬ₀ を読込んでから、ステップＳ１２、次いでステップＳ１３へと移行する。これら、ステップＳ１２及びステップＳ１３では、自車両が捕捉した先行車に対して目標車間距離を含む所定範囲内で追従する、すなわち、目標車間距離Ｌ_T を大方維持した定常追従走行状態にあるか否かを判定する。
【００３６】
先ず、ステップＳ１２では、前記ステップＳ１１で読込んだ相対車速ΔＶ₀ が、−ΔＶ_TH を超え、且つΔＶ_TH 未満の第2の設定範囲内であるか否かを判定し、この判定結果が−ΔＶ_TH ＜ΔＶ₀ ＜ΔＶ_TH であるときは、捕捉した先行車と略等しい速度で走行中であると判断して、ステップＳ１３に移行する。
このステップＳ１３では、前記ステップＳ１１で読込んだ車間距離偏差ΔＬ₀が、−ΔＬ_TH を超え、且つΔＬ_TH 未満の第2の所定範囲内であるか否かを判定する。この判定結果が−ΔＬ_TH ＜ΔＬ₀ ＜ΔＬ_TH であるときは、捕捉した先行車に対し、目標車間距離Ｌ_T と略等しい車間距離を有していると判断して、ステップＳ１４で切換フラグＦ_S を定常追従走行状態であることを表す“１”にセットしてから後述するステップＳ１５に移行する。
【００３７】
一方、前記ステップＳ１２の判定結果がΔＶ₀ ≦−ΔＶ_TH 、又はΔＶ₀ ≧ΔＶ_TH であるときには、先行車に対して接近傾向、又は離間傾向にあるものと判断して、切換フラグＦ_S を“０”にリセットしたまま、ステップＳ１５に移行する。また、前記ステップＳ１３の判定結果がΔＬ₀ ≦−ΔＬ_TH 、又はΔＬ₀ ≧ΔＬ_TH であるときには、捕捉した先行車との車間距離が目標車間距離Ｌ_T から離間していると判断して、切換フラグＦ_S を“０”にリセットしたまま、ステップＳ１５に移行する。さらに、前記ステップＳ９の判定結果が捕捉フラグＦ_C＝１であるときは、先行車の捕捉状態を継続しているものと判断してステップＳ１５に移行する。
【００３８】
ステップＳ１５では、切換フラグＦ_S が“１”にセットされているか否かを判定しており、この判定結果が切換フラグＦ_S＝０であるときは、先行車に対する実際の車間距離Ｌが目標車間距離Ｌ_T から離間傾向にある、若しくはその可能性があって定常追従走行状態ではないものと判断してステップＳ１６に移行する。
このステップＳ１６では、今回の補正車速指令値Ｖ^*'_(n) が、前回の最終補正車速指令値Ｖ^*''_(n-1) より大きいか否かを判定しており、この判定結果がＶ^*'_(n) ＞Ｖ^*''_(n-1) であるときは、自車両が加速するものと判断してステップＳ１７に移行する。このステップＳ１７では、補正車速指令値Ｖ^*'の変化率を制限する車速変化率制限値Ｖ^* _RATE を、通常制限値としての加速用車速変化率制限値Ｖ^* _RATE-A に設定してから後述するステップＳ２０に移行する。
【００３９】
一方、前記ステップＳ１７の判定結果がＶ^*'_(n) ≦Ｖ^*''_(n-1) であるときは、自車両が車速を維持するか、又は減速するもの判断してステップＳ１８に移行する。このステップＳ１８では、車速変化率制限値Ｖ^* _RATE を、通常制限値としての減速用車速変化率制限値Ｖ^* _RATE-D に設定してから後述するステップＳ２０に移行する。
【００４０】
また、前記ステップＳ１５の判定結果が切換フラグＦ_S＝１であるときは、自車両が捕捉した先行車に対して目標車間距離Ｌ_T を大方維持した定常追従走行状態にあると判断してステップＳ１９に移行する。
ステップＳ１９では、前記ステップＳ１１で読込んだ相対車速ΔＶ₀ 及び車間距離偏差ΔＬ₀ に基づいて、基本制限値Ｖ^* _RATE-B 及び制限値補正定数Ｋ_RATE を夫々算出した後、下記（８）式に基づいて車速変化率制限値Ｖ^* _RATE を演算してから後述するステップＳ２０に移行する。
【００４１】
Ｖ^* _RATE ＝Ｖ^* _RATE-B×Ｋ_RATE ・・・・・・・・・（８）
ここで、基本制限値Ｖ^* _RATE-B は、図３に示すように、相対車速ΔＶ₀ と車速変化率基本制限値Ｖ^* _RATE-B との関係を表した基本制限値算出用制御マップを参照して、相対車速ΔＶ₀ から算出する。この基本制限値算出用制御マップは、先行車追従制御コントローラ３が有するメモリに予め記憶されている。
【００４２】
基本制限値算出用制御マップは、図３に示すように、横軸に相対車速ΔＶ₀ を、縦軸に基本制限値Ｖ^* _RATE-B をとった座標系で表されている。そして、相対車速ΔＶ₀ が零から正方向に向けて第１の設定範囲としての加速側リミット値ΔＶ_ACC まで増加するときに、これに比例して基本制限値Ｖ^* _RATE-B も、正値の制限値Ｖ^* _RATE-B1 から正の定常値Ｖ^* _RATE-A まで直線的に増加し、相対車速ΔＶ₀ が加速側リミット値ΔＶ_ACC 以上となるときに、基本制限値Ｖ^* _RATE-B がＶ^* _RATE-A を維持するように設定されている。一方、相対車速ΔＶ₀ が零から負方向に向けて第１の設定範囲としての減速側リミット値ΔＶ_DEC まで減少するときに、基本制限値Ｖ^* _RATE-B も比例して、負の制限値Ｖ^* _RATE-B2 から負の定常値Ｖ^* _RATE-D まで直線的に減少し、相対車速ΔＶ₀ が減速側リミット値ΔＶ_DEC 以下となるときに、基本制限値Ｖ^* _RATE-B は、Ｖ^* _RATE-D を維持するように設定されている。
【００４３】
さらに、相対車速ΔＶ₀ が先行車に接近する方向に変化するときの基本制限値Ｖ^* _RATE-B の絶対値が、先行車から離間する方向に変化するときの基本制限値Ｖ^* _RATE-B の絶対値に比較して大きな値となるように、加速側のＶ^* _RATE-B1 及びＶ^* _RATE-A 、並びに減速側のＶ^* _RATE-B2 及びＶ^* _RATE-D が夫々設定されている。なお、加速側リミット値ΔＶ_ACC 及び減速側リミット値ΔＶ_DEC の夫々は、前述した−ΔＶ_TH を超え、ΔＶ_TH 未満の設定範囲内の値である。
【００４４】
また、制限値補正定数Ｋ_RATE は、図４に示すように、車間距離偏差ΔＬ₀ と制限値補正定数Ｋ_RATE との関係を表した制限値補正定数算出用制御マップを参照して、車間距離偏差ΔＬ₀ から算出する。この制限値補正定数算出用制御マップは、先行車追従制御コントローラ３が有するメモリに予め記憶されている。
この制限値補正定数算出用制御マップは、図４に示すように、横軸に車間距離偏差ΔＬ₀ を、縦軸に制限値補正定数Ｋ_RATE をとった座標系で表されている。
そして、車間距離偏差ΔＬ₀ が零であるときは、制限値補正定数Ｋ_RATE が“１”よりも小さなＫ_RATE-MIN となり、この状態から車間距離偏差ΔＬ₀ が正方向に第１の所定範囲としての加速側リミット値ΔＬ_ACC まで増加するときに、制限値補正定数Ｋ_RATE も比例して、Ｋ_RATE-MIN を超えて“１”まで直線的に増加し、車間距離偏差ΔＬ₀ が加速側リミット値ΔＬ_ACC 以上となるときに、制限値補正定数Ｋ_RATE は、“１”を維持するように設定されている。一方、車間距離偏差ΔＬ₀ が零から負方向に第１の所定範囲としての減速側リミット値ΔＬ_DEC まで減少するときに、制限値補正定数Ｋ_RATE も比例して、Ｋ_RATE-MIN を超えて“１”まで直線的に増加し、車間距離偏差ΔＬ₀ が負の減速側リミット値ΔＬ_DEC 以下となるときに、制限値補正定数Ｋ_RATE は、“１”を維持するように設定されている。
【００４５】
さらに、車間距離偏差ΔＬ₀ が車間距離Ｌの短くなる方向に変化するときの制限値補正定数Ｋ_RATE が、車間距離Ｌが長くなる方向に変化するときの制限値補正定数Ｋ_RATE に比較して大きな値となるように、加速側リミット値ΔＬ_ACC 及び減速側リミット値ΔＬ_DEC が夫々設定されている。なお、加速側リミット値ΔＬ_ACC 及び減速側リミット値ΔＬ_DEC の夫々は、前述した−ΔＬ_TH を超え、ΔＬ_TH 未満の所定範囲内の値である。
【００４６】
また、ステップＳ２０では、前回の最終補正車速指令値Ｖ^*''_(n-1) から今回の補正車速指令値Ｖ^*'_(n) を減算した偏差の絶対値が、車速変化率制限値Ｖ^* _RATE より大きいか否かを判定している。この判定結果が｜Ｖ^*''_(n-1) −Ｖ^*'_(n)｜≦｜Ｖ^* _RATE｜であるときは、車速変化量が小さい範囲に納まって今回の補正車速指令値Ｖ^*'_(n) を制限する必要はないと判断してステップＳ２１に移行する。このステップＳ２１では、切換フラグＦ_S を“０”にリセットして、続くステップＳ２２で今回の補正車速指令値Ｖ^*'_(n) を、最終補正車速指令値Ｖ^*''_(n) として車速指令部４へ出力してから、前記ステップＳ１に戻る。
【００４７】
一方、前記ステップＳ２０の判定結果が｜Ｖ^*''_(n-1) −Ｖ^*'_(n)｜＞｜Ｖ^* _RATE｜であるときは、前回の最終補正車速指令値Ｖ^*''_(n-1) から今回の補正車速指令値Ｖ^*'_(n) への車速変化量が大きいと判断してステップＳ２３に移行する。このステップＳ２３では、前回の最終補正車速指令値Ｖ^*''_(n-1) に車速変化率制限値Ｖ^* _RATE を加算したものを、今回の最終補正車速指令値Ｖ^*''_(n) として車速制御部４へ出力してから、前記ステップＳ１に戻る。
【００４８】
ここで、車間距離センサ１が車間距離検出手段に対応し、先行車追従制御コントローラ３における目標車間距離演算部３３が目標車間距離設定手段に対応し、先行車追従制御コントローラ３における車速指令値演算部３４が指令値算出手段に対応し、車速制御部４、スロットルアクチュエータ５、自動ブレーキアクチュエータ６及びトランスミッションアクチュエータ７が自車速制御手段に対応し、図２の車速指令値変化率制限処理におけるステップＳ９、ステップＳ１１、ステップＳ１２及びステップＳ１３の処理が捕捉開始時追従判定手段に対応し、図２の車速指令値変化率制限処理におけるステップＳ１５、ステップＳ１９、ステップＳ２０及びステップＳ２３の処理が速度変化率制限手段に対応している。
【００４９】
次に、上記実施形態における動作について説明する。
今、自車両が直線的な平坦路を、追従走行に適した先行車両を車間距離センサ１で捕捉した状態で走行しているとする。このときは、先ず、車間距離センサ１で検出する先行車両との車間距離Ｌから、相対速度ΔＶを算出し、この相対車速ΔＶ及び車速センサ２で検出される自車速Ｖから前記（２）式に基づいて車間距離指令値Ｌ^* を算出する。
【００５０】
この車間距離指令値Ｌ^* に基づいて、目標車間距離演算部３３が、目標車間距離Ｌ_T を演算してから車速指令値演算部３４へ出力し、車速指令値演算部３４が入力された目標車間距離Ｌ_T に応じた車速指令値Ｖ^* を演算し、補正車速指令値演算部３６へ出力する。続いて、この補正車速指令値演算部３６が、入力された車速指令値Ｖ^* から、前置補償車速指令値演算部３５より供給される補償車速指令値Ｖ_C を減算して補正車速指令値Ｖ^*'を算出することにより、車間距離制御系における安定性を確保しつつ、応答性の向上を図っている。
【００５１】
さらに、補正車速指令値Ｖ^*'を、補正車速指令値変化率制限部３７に通して、その変化率に制限を掛けてから最終補正車速指令値Ｖ^*''を生成する。そして、この最終補正車速指令値Ｖ^*''を車速制御部へ供給して、ロバストモデルマッチング手法で駆動力指令値Ｆ^* を算出し、この駆動力指令値Ｆ^* に基づいてスロットルアクチュエータ５、自動ブレーキアクチュエータ６及びトランスミッションアクチュエータ７を制御することにより、車間距離センサ１で検出した実際の車間距離Ｌが目標車間距離Ｌ_T に収束するように自車速制御を行う。
【００５２】
こうして、自車両が、概ね一定の速度で走行している先行車に対して車間距離指令値Ｌ^*を維持した理想的な追従走行状態にあるときは、自車速Ｖが、先行車の車速Ｖｔと略一致しており、相対車速ΔＶは、図５（ｂ）に示すように、略０［ｋｍ／ｈ］となる。
ここで、車間距離の変動に応じて算出される補正車速指令値Ｖ^*'は、補正車速指令値変化率制限部３７にて、その変化率に制限が掛けられている。この先行車への理想的な追従走行状態にあるときには、補正車速指令値Ｖ^*'_(n) の変化率も十分に低く、既に、前回の最終補正車速指令値Ｖ^*''_(n-1) から今回の補正車速指令値Ｖ^*'_(n) を減じた偏差の絶対値が、車速変化率制限値Ｖ^* _RATE の絶対値以下となっており（ステップＳ２０の判定が“No”）、切換フラグＦ_C は“０”にリセットされている（ステップＳ２１）。したがって、補正車速指令値Ｖ^*'は、通常制限値で制限されている（ステップＳ１５の判定が“No”）。
【００５３】
すなわち、今回の補正車速指令値Ｖ^*'_(n) が、前回の最終補正車速指令値Ｖ^*''_(n-1) に対して、増加するときには、加速用車速変化率制限値Ｖ^* _RATE-A 以下に（ステップＳ１７）、逆に減少するときには、減速用車速変化率制限値Ｖ^* _RATE-D 以下となるように（ステップＳ１８）、補正車速指令値Ｖ^*'_(n) の変化率を制限することで、先行車への追従走行中に過大な加減速が発生することを抑制している。この、減速用車速変化率制限値Ｖ^* _RATE-D の絶対値は、加速用車速変化率制限値Ｖ^* _RATE-A の絶対値に比べて大きく設定されているので、加速時よりも減速時の方が大きな車速変化率を許容している。
【００５４】
ここで、直線的な平坦路から、例えば、勾配が急な上り坂の頂上付近や曲率の大きいカーブに差し掛かると、図５（ｅ）に示すように、車間距離センサ１が時点ｔ₀ で先行車を一時的に見失ってしまう（ステップＳ２の判定が“No”）。
そこで、先行車追従制御コントローラ３は、先行車を見失った時点ｔ₀ からタイマＴのカウントを開始すると供に、先行車を見失った時点の車速を維持するために、前回の処理段階で生成された最終補正車速指令値Ｖ^*''_(n-1) （以下、見失い時車速指令値Ｖ^*''_L と称す）を継続して車速制御部４へ出力する（ステップＳ５）。この見失い時車速指令値Ｖ^*''_L は、先行車が捕捉されず、且つタイマＴが所定値Ｔ₁ 未満である間、継続して出力される（ステップＳ７の判定が“No”）。
【００５５】
そして、先行車が依然として捕捉されず、図５（ｅ）に示すように、時点ｔ₁ でタイマＴが所定値Ｔ₁ 以上となるときに（ステップＳ７の判定が“Yes”）、見失い時車速指令値Ｖ^*''_L に替えて、予め運転者により設定された車速設定値Ｖ_SET が補正車速指令値Ｖ^*'として出力される。
このとき、車速設定値Ｖ_SET に対応した補正車速指令値Ｖ^*'が、見失い時車速指令値Ｖ^*''_L に対して大きく、加速状態への移行となる場合、その差分が加速用車速変化率制限値Ｖ^* _RATE-A 以下であるときには、補正車速指令値Ｖ^*'を最終補正車速指令値Ｖ^*''_(n) として車速制御部４へ出力する（ステップＳ２２）。
一方、補正車速指令値Ｖ^*'と見失い時車速指令値Ｖ^*''_Lとの差分が、加速用車速変化率制限値Ｖ^* _RATE-A を超えているときには、見失い時車速指令値Ｖ^*''_L に加速用車速変化率制限値Ｖ^* _RATE-A を加算した値を最終補正車速指令値Ｖ^*''_(n) として車速制御部４へ出力する（ステップＳ２３）。
【００５６】
したがって、図５（ｃ）に示すように、時点ｔ₂ 以降の最終補正車速指令値Ｖ^*''_(n) は（以下、単に車速指令値Ｖ^*''と称す）、自車速Ｖが車速設定値Ｖ^*''に到達するまで、加速用車速変化率制限値Ｖ^* _RATE-A 以下の変化率に制限されつつ、徐々に増加する。そして、これに応じるように、図５（ｄ）に示した駆動力指令値Ｆ^*も徐々に値を増してゆくことで、自車両が加速してゆく。
【００５７】
そして、自車両が、勾配が急な上り坂の頂上付近や曲率の大きいカーブを抜け出し、図５（ｅ）の時点ｔ₂ で示すように、車間距離センサ１が再び先行車を捕捉したとする（ステップＳ９の判定が“No”）。
先ず、先行車追従制御コントローラ３は、先行車を捕捉した時点ｔ₂ における先行車との相対車速ΔＶ₀ 及び車間距離偏差ΔＬ₀ を読込む（ステップＳ１１）。次いで、これら相対車速ΔＶ₀ が設定範囲内（−ΔＶ_TH ＜ΔＶ₀ ＜ΔＶ_TH ）で、且つ車間距離偏差ΔＬ₀ が所定範囲内（−ΔＬ_TH ＜ΔＬ₀ ＜ΔＬ_TH ）であるかを判定して（ステップＳ１２及びステップＳ１３）、自車両が再捕捉した先行車に対する目標車間距離Ｌ_T を大方維持している定常追従走行状態にあるか否かを確認する。
【００５８】
仮に、先行車を見失っていた間に、この先行車が減速又は加速しており、車間距離センサ１で再捕捉したときに、相対車速ΔＶ₀ が、−ΔＶ_TH 以下やΔＶ_TH 以上である（ステップＳ１２の判定が“No”）、又は車間距離偏差ΔＬ₀ が、−ΔＬ_TH 以下やΔＬ_TH 以上である（ステップＳ１３の判定が“No”）、すなわち定常追従走行状態から逸脱している場合には、比較的大きな加減速を許容する必要がある。そのため、先行車を再び捕捉した後に算出される補正車速指令値Ｖ^*'の変化率を、通常制限値の加速用車速変化率制限値Ｖ^* _RATE-A 又は減速用車速変化率制限値Ｖ^* _RATE-D 以下に制限することで（ステップＳ１７又はステップＳ１８）、急激な加減速を抑制しつつも、目標車間距離Ｌ_T への速やかな収束を図る。
【００５９】
一方、先行車を再捕捉した時点ｔ₂ で、図５（ｃ）に示すように、相対車速ΔＶ₀ が−ΔＶ_TH を超え、ΔＶ_TH 未満の設定範囲内で（ステップＳ１２の判定が“Yes”）、且つ図５（ａ）に示すように、目標車間距離に対する実際に計測した車間距離の差分（車間距離偏差ΔＬ₀）が−ΔＬ_TH を超え、ΔＬ_TH 未満の所定範囲内である（ステップＳ１３の判定が“No”）、すなわち、自車両が先行車に対する定常追従走行状態にある場合には、上記のように比較的大きな加減速が必ずしも必要とはならない。
【００６０】
ここで、図５（ｃ）における時点ｔ₂ 以降、一点差線で示す元々の補正車速指令値Ｖ^*'を、上述した通常制限値で制限した場合の車速指令値Ｖ^*''を点線で示すように、過大な変化率を抑制してはいるが、それでも、この車速指令値Ｖ^*''に対応した駆動力指令値Ｆ^*を図５（ｄ）の点線で示すように、その変化率は比較的大きく、また不連続である。
【００６１】
そこで、自車両が先行車に対する定常追従走行状態にある場合には、目標車間距離Ｌ_T への更なる収束を、より繊細に行うことが望ましい。そのため、先行車を再び捕捉した後に算出される補正車速指令値Ｖ^*'の変化率を、先行車を捕捉した時点ｔ₂ の相対車速ΔＶ₀ 及び車間距離偏差ΔＬ₀ に基づいて通常制限値に比較して小さくなるように、車速変化率制限値Ｖ^* _RATE を演算する（ステップＳ１９）。
【００６２】
したがって、例えば、相対車速ΔＶ₀ が、零から減速側リミット値ΔＶ_DEC 未満の値であるときには、基本制限値Ｖ^* _RATE-B の絶対値がＶ^* _RATE-D の絶対値よりも小さい値となる。さらに、車間距離偏差ΔＬ₀ が、零から減速側リミット値ΔＬ_DEC 未満の値であるときには、制限値補正定数Ｋ_RATE が、“１”よりも小さい値となる。
【００６３】
こうして、基本制限値Ｖ^* _RATE-B に制限値補正定数Ｋ_RATE を乗じて演算する車速変化率制限値Ｖ^* _RATE が通常制限値よりも小さくなることで、図５（ｃ）における時点ｔ₂ 以降の実線で示すように、補正車速指令値Ｖ^*'の変化率を更に小さく制限する。その結果、図５（ｄ）の実線で示すように、比較的大きな変化を適度に抑制した連続的な駆動力指令値Ｆ^*を出力することで、運手者に与え兼ねない違和感を確実に抑制している。
【００６４】
その後、先行車との実際の車間距離Ｌが目標車間距離Ｌ_T に徐々に収束してくると、これに伴うように、算出される補正車速指令値Ｖ^*'_(n) の変化率も徐々に低下してくる。そして、前回の最終補正車速指令値Ｖ^*''_(n-1) から今回の補正車速指令値Ｖ^*'_(n) を減じた偏差の絶対値が、車速変化率制限値Ｖ^* _RATE の絶対値以下となった後は（ステップＳ２０の判定が“No”）、車速変化率制限値Ｖ^* _RATE が通常制限値に復帰する（ステップＳ２１）。
【００６５】
また、先行車を見失ってからカウントを開始するタイマＴが所定値Ｔ₁ 未満であるときに、先行車を再び捕捉した場合は、先行車を見失っていた時間も僅かで、尚且つ見失い時車速指令値Ｖ^*''_L が継続して出力されているので、先行車への定常追従走行状態にある可能性が大きい。
そして、実際に先行車への定常追従走行状態にあることが確認されると（ステップＳ１２及びステップＳ１３の判定が供に“Yes”）、目標車間距離Ｌ_T への更なる収束を、より繊細に行うために、補正車速指令値Ｖ^*'の変化率を、先行車を捕捉した時点ｔ₂ の相対車速ΔＶ₀ 及び車間距離偏差ΔＬ₀ に基づいて通常制限値に比較して小さくなるように、車速変化率制限値Ｖ^* _RATE を演算する（ステップＳ１９）。仮に、先行車を見失っていた僅かな間に、この先行車が急に減速又は加速しており、定常追従走行状態から逸脱している場合は（ステップＳ１２又はステップＳ１３の何れかの判定が“No”）、比較的大きな加減速を許容するために、補正車速指令値Ｖ^*'の変化率を、通常制限値により制限する（ステップＳ１７、又はステップＳ１８）。
【００６６】
また、先行車への追従走行状態にあるときに、制動制御によるノーズダイブが生じることで、先行車を見失った場合について説明する。なお、この制動制御とは極一時的なものを指している。
したがって、直ちに車両体勢を立て直して先行車に追従するとき、先行車を見失っていた時間が僅かであっても、先行車を見失う程のノーズダイブを招来する制動制御により、先行車への定常追従走行状態にある可能性は低い。
【００６７】
したがって、実際に先行車への定常追従走行状態から逸脱している場合は（ステップＳ１２又はステップＳ１３の何れかの判定が “No”）、比較的大きな加減速を許容する（ステップＳ１７、又はステップＳ１８）。仮に、先行車を見失っている間に、この先行車も自車両と同様に減速していて、再び捕捉したときに、定常追従走行状態にあるときには、目標車間距離Ｌ_T への更なる収束を、より繊細に行う（ステップＳ１９）。
【００６８】
なお、上記第１の実施形態における図３の基本制限値算出用制御マップでは、相対車速ΔＶ₀ が減速側リミット値ΔＶ_DEC から加速側リミット値ΔＶ_ACC の設定範囲内で変化するとき、これに応じて基本制限値Ｖ^* _RATE-B が直線的に変化する構成について説明したが、これに限定されるものではない。すなわち、相対車速ΔＶ₀ の変動に応じて基本制限値Ｖ^* _RATE-B が曲線状に変化したり、複数の段階で変化したりしてもよい。
【００６９】
また、上記第１の実施形態における図３の基本制限値算出用制御マップでは、相対車速ΔＶ₀ が零であるときは、基本制限値Ｖ^* _RATE-B が、減速側のＶ^* _RATE-B2 となるように設定されているが、これに限定されるものではなく、加速側のＶ^* _RATE-B1 となるように設定してもよい。
さらに、上記第１の実施形態における図４の制限値補正定数算出用制御マップでは、車間距離偏差ΔＬ₀ が減速側リミット値ΔＬ_DEC から加速側リミット値ΔＬ_ACC の所定範囲内で変化するとき、これに応じて制限値補正定数Ｋ_RATE が直線的に変化する構成について説明したが、これに限定されるものではない。すなわち、車間距離偏差ΔＬ₀ の変動に応じて制限値補正定数Ｋ_RATE が曲線状に変化したり、複数の段階で変化させたりしてもよい。
【００７０】
さらに、上記第１の実施形態においては、車間距離指令値演算部３１で先行車車速Ｖｔに基づいて車間距離指令値Ｌ^*を演算する場合について説明したが、これに限定されるものではない。すなわち、先行車車速Ｖｔに代えて自車速Ｖを適用し、下記（９）式に示すように、車間距離指令値Ｌ^*を自車速Ｖの関数として演算するようにしてもよい。
【００７１】
Ｌ^*＝ａ'・Ｖ＋Ｌ_OF' ・・・・・・・・・（９）
ここで、ａ'は係数、Ｌ_OF'は車両停車時のオフセット値である。
さらにまた、図６に示すように、予め設定した車間距離設定値Ｌ_SET を車間距離指令値Ｌ^*として使用することで車間距離指令値演算部３１を省略したり、更には前置補償車速指令値演算部３５及び補正車速指令値演算部３６を省略したりしてもよい。
【００７２】
また、上記第１の実施形態においては、車速指令値の変化率を車速指令値制限Ｖ^* _RATE で制限する構成について説明したが、これに限定されるものではない。すなわち、車速制御部４で演算される駆動力指令値Ｆ^*の変化率を制限してもよく、要は、自車速の変化率を制限することができればよい。
以上のように、車間距離検出センサ１で先行車の捕捉を開始したときの自車両が、先行車に目標車間距離を含む所定範囲内で追従した定常追従走行状態にあると判断される場合は、車間距離センサ１で検出する車間距離Ｌに基づいて、補正車速指令値Ｖ^*'の変化率を、通常制限値に比較して小さい車速変化率制限値Ｖ^* _RATE で制限することで、加減速の大きな変化を確実に抑制し、運転者に与える違和感を解消することができる。
【００７３】
また、先行車との相対車速ΔＶ₀ 及び車間距離Ｌと目標車間距離Ｌ_T との車間距離偏差ΔＬ₀ を検出して、相対車速ΔＶ₀ が零を含む第１の設定範囲としてのΔＶ_DEC を超え、且つΔＶ_ACC 未満であるときに、又は車間距離偏差ΔＬ₀ が零を含む第１の所定範囲内としてのΔＬ_DEC を超え、且つΔＬ_ACC 未満であるときに、補正車速指令値Ｖ^*'の変化率を、通常制限値に比較して小さい車速変化率制限値Ｖ^* _RATE で制限しているので、加減速の大きな変化を的確に抑制し、運転者に与える違和感を解消することができる。
【００７４】
さらに、車間距離センサ１で先行車の捕捉を開始した場合、相対車速ΔＶ₀ が零を含む第２の設定範囲内としての−ΔＶ_TH を超え、且つΔＶ_TH 未満であるときで、且つ車間距離偏差ΔＬ₀ が零を含む第２の所定範囲内としての−ΔＬ_TH を超え、且つΔＬ_TH 未満であるときに、定常追従走行状態であると判定するので、自車両が先行車との目標車間距離を大方維持しているか否かを、正確に判定することができる。
【００７５】
さらにまた、相対車速ΔＶ₀ 、又は車間距離偏差ΔＬ₀ の夫々が零に近づくほど、車速変化率制限値Ｖ^* _RATE を小さい値に設定するように構成されているので、加減速の大きな変化をより的確に抑制し、運転者に与える違和感を解消することができる。
また、相対車速ΔＶ₀ が先行車に接近する方向に変化するときの車速変化率制限値Ｖ^* _RATE を、先行車から離間する方向に変化するときの車速変化率制限値Ｖ^* _RATE に比較して大きな値に設定するように構成されているので、減速時には加速時に比べて大きな車速変化率を許容することにより、安全性を高めることができる。
【００７６】
さらに、車間距離偏差ΔＬ₀ が車間距離の短くなる方向に変化するときの車速変化率制限値Ｖ^* _RATE を、車間距離Ｌが長くなる方向に変化するときの車速変化率制限値Ｖ^* _RATE に比較して大きな値に設定するように構成されているので、減速時には加速時に比べて大きな車速変化率を許容することにより、安全性を高めることができる。
【００７７】
さらにまた、車速指令値演算部３４で演算する車速指令値の変化率を車速変化率制限値Ｖ^* _RATE で制限することにより、自車両の速度変化率を容易に制限することができる。
次に本発明の第２の実施形態を図７に基づいて説明する。
この第２の実施形態は、前述した第１の実施形態における車速変化率制限値Ｖ^* _RATE の演算方法を変化させたものである。
【００７８】
すなわち、第２の実施形態では、先行車追従制御コントローラ３で実行される車速指令値変化率制限処理を図７に示すように、前述した図２のステップＳ１９の処理が、車速変化率制限値Ｖ^* _RATE を基本制限値Ｖ^* _RATE-B のみに基づいて演算するステップＳ３０に変更されたことを除いては、第１の実施形態と同様の処理手順で構成されるので、図２との対応部分には同一符号を付し、その詳細説明はこれを省略する。
【００７９】
したがって、例えば、自車両が再捕捉した先行車に対して定常追従走行状態にある場合（ステップＳ１２及びステップＳ１３の判定が供に“Yes”）、相対車速ΔＶ₀ が、零を超え、且つ減速側リミット値ΔＶ_DEC 未満となるときには、基本制限値Ｖ^* _RATE-B の絶対値が通常制限値としてのＶ^* _RATE-D の絶対値よりも小さい値となる。また、相対車速ΔＶ₀ が、零を超え、且つ加速側リミット値ΔＶ_ACC 未満となるときには、基本制限値Ｖ^* _RATE-B の絶対値が通常制限値としてのＶ^* _RATE-A の絶対値よりも小さい値となる。
【００８０】
なお、上記第２の実施形態においては、相対車速ΔＶ₀ に基づいて、基本制限値Ｖ^* _RATE-B を演算する構成について説明したが、これに限定されるものではない。すなわち、例えば、前述した図４の制限値補正定数算出用制御マップと同様の特性を有する制御マップを参照して、相対車速ΔＶ₀ から制限値補正定数Ｋ_RATE を算出し、これを予め設定された一定基本制限値Ｖ^* _RATE-R に乗じることで、車速変化率制限値Ｖ^* _RATE を小さくしてもよく、要は、相対車速ΔＶ₀ に基づいて、車速変化率制限値Ｖ^* _RATE を小さくすることができれば、如何なる演算方法を用いてもよい。
【００８１】
以上のように、先行車との相対車速ΔＶ₀ を検出して、相対車速ΔＶ₀ が零を含む第１の設定範囲としてのΔＶ_DEC を超え、且つΔＶ_ACC 未満であるときに、補正車速指令値Ｖ^*'の変化率を、通常制限値に比較して小さい車速変化率制限値Ｖ^* _RATE で制限しているので、加減速の大きな変化を容易に抑制し、運転者に与える違和感を解消することができる。
【００８２】
次に本発明の第３の実施形態を図８に基づいて説明する。
この第３の実施形態は、前述した第１の実施形態における車速変化率制限値Ｖ^* _RATE の演算方法を変化させたものである。
すなわち、第３の実施形態では、先行車追従制御コントローラ３で実行される車速指令値変化率制限処理を図７に示すように、前述した図２のステップＳ１９の処理が、予め設定された一定基本制限値Ｖ^* _RATE-R に制限値補正定数Ｋ_RATE を乗じて車速変化率制限値Ｖ^* _RATE を演算するステップＳ３１に変更されたことを除いては、第１の実施形態と同様の処理手順で構成されるので、図２との対応部分には同一符号を付し、その詳細説明はこれを省略する。
【００８３】
因みに、一定基本制限値Ｖ^* _RATE-R は、前述した第１の実施形態における加速用車速変化率制限値Ｖ^* _RATE-A 又は減速用車速変化率制限値Ｖ^* _RATE-D 近傍の値に設定されている。
したがって、例えば、自車両が再び捕捉した先行車に対して定常追従走行状態にある場合（ステップＳ１２及びステップＳ１３の判定結果が供に“Yes”）、車間距離偏差ΔＬ₀ が、零を超え、且つ減速側リミット値ΔＬ_DEC 未満となるときに、制限値補正定数Ｋ_RATE が“１”よりも小さい値となる。また、車間距離偏差ΔＬ₀ が、零を超え、且つ加速側リミット値ΔＬ_ACC 未満となるときに、制限値補正定数Ｋ_RATE が“１”よりも小さい値となる。こうして制限値補正定数Ｋ_RATE が一定基本制限値Ｖ^* _RATE-R に乗算されることにより、通常制限値としてのＶ^* _RATE-D の絶対値よりも小さい値となる。
【００８４】
なお、上記第３の実施形態においては、車間距離偏差ΔＬ₀ から制限値補正定数Ｋ_RATE を演算する構成について説明したが、これに限定されるものではない。すなわち、例えば、前述した図３の基本制限値算出用制御マップと同様の特性を有する制御マップを参照して、車間距離偏差ΔＬ₀ から基本制限値Ｖ^* _RATE-B を演算することで、車速変化率制限値Ｖ^* _RATE を小さくしてもよく、要は、車間距離偏差ΔＬ₀ に基づいて、車速変化率制限値Ｖ^* _RATE を小さくすることができれば、如何なる演算方法を用いてもよい。
【００８５】
以上のように、車間距離Ｌと目標車間距離Ｌ_T との車間距離偏差ΔＬ₀ を検出して、車間距離偏差ΔＬ₀ が零を含む第１の所定範囲内としてのΔＬ_DEC を超え、且つΔＬ_ACC 未満であるときに、補正車速指令値Ｖ^*'の変化率を、通常制限値に比較して小さい車速変化率制限値Ｖ^* _RATE で制限しているので、加減速の大きな変化を容易に抑制し、運転者に与える違和感を解消することができる。
【００８６】
次に本発明の第４の実施形態を図９に基づいて説明する。
この第４の実施形態は、前述した第１の実施形態において、先行車を捕捉しない状態から捕捉する状態に復帰するまでの復帰時間に基づいて、自車両が先行車に対する定常走行状態にある可能性を予測するように構成したものである。
すなわち、この第４の実施形態では、先行車追従制御コントローラ３で実行される車速指令値変化率制限処理を図９に示すように、前述した第１の実施形態における図２のフローチャートにおいて、ステップＳ１０を処理した後に、ステップＳ４０を追加したことを除いては、第１の実施形態と同様の処理手順で構成されるので、図２との対応部分には同一符号を付し、その詳細説明はこれを省略する。
【００８７】
図９の車速指令値変化率制限処理では、ステップＳ１０で捕捉フラグＦ_C を“１”にセットし後にステップＳ４０に移行する。このステップＳ４０では、先行車を見失った時点ｔ₀ からカンウントを開始したタイマＴが所定値Ｔ^*未満であるか否かを判定している。この判定結果がＴ≧Ｔ^*であるときは、自車両が先行車に対して定常走行状態にある可能性は低いものと判断して、前記ステップＳ８に移行する。一方、判定結果がＴ＜Ｔ^*であるときは、先行車の見失いが一時的なものであると判断してステップＳ１１に移行する。なお、所定値Ｔ^*は、自車両が先行車に対する目標車間距離Ｌ_T を大方維持している可能性があるか否かを判定する値となるため、前述した所定値比較的長く設定されている。
【００８８】
したがって、例えば、先行車の車線変更により追従走行に適した先行車を失い、その後、ある程度の時間を経て新たな先行車を捕捉した場合など、先行車を見失ってからカウントを開始したタイマＴが所定値Ｔ^*以上であるときには（ステップＳ４０の判定が“No”）、自車両が先行車に対して定常走行状態にある可能性は低い。そのため、比較的大きな加減速を許容するために、先行車を再び捕捉した後に算出される補正車速指令値Ｖ^*'の変化率を、通常制限値の加速用車速変化率制限値Ｖ^* _RATE-A 又は減速用車速変化率制限値Ｖ^* _RATE-D 以下に制限することで（ステップＳ１７又はステップＳ１８）、急激な加減速を抑制しつつも、目標車間距離Ｌ_T への速やかな収束を図る。
【００８９】
一方、タイマＴが所定値Ｔ^*未満であるときには（ステップＳ４０の判定が“Yes”）、先行車の見失いが一時的なものであると判断して、実際に自車両が先行車に対して定常走行状態にあるか否かを判定してゆく（ステップＳ１２及びステップＳ１３）。
以上のように、車間距離センサ１で先行車を捕捉しない状態から捕捉する状態に復帰するまでのタイマＴが所定値Ｔ^*未満であるときには、車間距離Ｌに基づいて車速変化率を小さく制限し、タイマＴが所定値Ｔ^*以上であるときには、通常制限値を用いて車速変化率の制限を行うように構成されているので、先行車の見失い時間が長かった場合は、捕捉開始時における定常追従走行の判定処理を省略して、車速指令値変化率制限処理を簡略化することができる。
【００９０】
なお、上記第４の実施形態においては、前述した第１実施形態のように、相対車速ΔＶ₀ 及び車間距離偏差ΔＬ₀ に基づいて、車速変化率制限値Ｖ^* _RATE を演算する構成について説明したが、これに限定されるものではない。すなわち、前述した第２実施形態、又は第３実施形態のように、相対車速ΔＶ₀ 又は車間距離偏差ΔＬ₀ の何れかに基づいて、車速変化率制限値Ｖ^* _RATE を演算してもよい。
【図面の簡単な説明】
【図１】本発明における第１実施形態を示す概略構成図である。
【図２】第１実施形態における車速指令値変化率制限処理の一例を示すフローチャートである。
【図３】基本制限値算出用制御マップである。
【図４】制限値補正定数算出用制御マップである。
【図５】第１実施形態の動作を説明するタイムチャートである。
【図６】車間距離指令値演算部３１、前置補償車速指令値演算部３５、及び補正車速指令値演算部３６を省略した場合の概略構成図である。
【図７】第２実施形態における車速指令値変化率制限処理の一例を示すフローチャートである。
【図８】第３実施形態における車速指令値変化率制限処理の一例を示すフローチャートである。
【図９】第４実施形態における車速指令値変化率制限処理の一例を示すフローチャートである。
【符号の説明】
１ 車間距離センサ（車間距離検出手段）
２ 車速センサ
３ 先行車追従制御コントローラ
４ 車速制御部（自車速制御手段）
５ スロットルアクチュエータ（自車速制御手段）
６ 自動ブレーキアクチュエータ（自車速制御手段）
７ トランスミッションアクチュエータ（自車速制御手段）
３１ 車間距離指令値演算部
３２ 目標車間距離演算用定数決定部
３３ 目標車間距離演算部（目標車間距離設定手段）
３４ 車速指令値演算部（指令値算出手段）
３５ 前置補償車速指令値演算部
３６ 補正車速指令値演算部
３７ 補正車速指令値変化率制限部（速度変化率制限手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inter-vehicle distance control device capable of following traveling while maintaining a target inter-vehicle distance from a preceding vehicle.
[0002]
[Prior art]
Conventionally, as this kind of inter-vehicle distance control device, for example, a device described in JP 2000-135934 A has been proposed.
In this conventional example, the inter-vehicle distance sensor detects the inter-vehicle distance from the preceding vehicle, further calculates the relative speed and inter-vehicle distance command value with the preceding vehicle, and the inter-vehicle distance according to the inter-vehicle distance deviation and the relative speed. Decide the damping coefficient and natural frequency of the control system, calculate the target inter-vehicle distance and target relative speed from the inter-vehicle distance command value using the filter specified by the damping coefficient and natural frequency by the vehicle speed command value calculating means, Inter-vehicle distance control that obtains the desired inter-vehicle distance response in various following scenes by calculating the vehicle speed command value based on the vehicle speed detection value, the relative speed detection value, the inter-vehicle distance detection value, the target inter-vehicle distance, and the target relative speed. An apparatus is described.
[0003]
[Problems to be solved by the invention]
However, in the above conventional example, during follow-up running while maintaining the target inter-vehicle distance from the preceding vehicle, for example, near the top of an uphill with a steep slope or a curve with a large curvature, nose dive by braking control If there is a situation where the preceding vehicle actually exists, a situation may occur in which the inter-vehicle distance sensor loses sight of the preceding vehicle. In this case, the relative positional relationship between the host vehicle and the preceding vehicle changes between the time when the inter-vehicle distance sensor temporarily loses sight of the preceding vehicle and the time when the preceding vehicle is captured again. Inter-vehicle distance deviation, which is the deviation from the inter-vehicle distance, and relative speed deviation, which is the deviation between the relative speed detection value and the target relative speed. There is an unresolved problem that discontinuities occur in the vehicle and may cause the driver to feel uncomfortable.
[0004]
Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and when the inter-vehicle distance detection means captures the preceding vehicle that is temporarily lost, a discontinuity point is present in the inter-vehicle distance control. An object of the present invention is to provide an inter-vehicle distance control device that can surely prevent the occurrence and suppress the uncomfortable feeling given to the driver.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the inter-vehicle distance control device according to the present invention is configured so that the inter-vehicle distance detected by the inter-vehicle distance detection means converges to the target inter-vehicle distance set by the target inter-vehicle distance setting means. The vehicle speed command value is calculated by the command value calculation means, and the vehicle speed of the host vehicle is controlled by the host vehicle speed control means based on the vehicle speed command value, but the state in which the preceding vehicle is not captured by the inter-vehicle distance detection means is changed. The speed change rate of the own vehicle speed control means based on the inter-vehicle distance detected by the inter-vehicle distance detection means when returning and in a steady following traveling state that follows the preceding vehicle within a predetermined range including the target inter-vehicle distance. Is limited to a small size.
[0006]
【The invention's effect】
According to the inter-vehicle distance control device according to the present invention, the inter-vehicle distance detection means returns to the state where the preceding vehicle is not captured by the inter-vehicle distance detection means, returns to the capture state, and is in the steady following running state. Since the speed change rate of the own vehicle speed control means is limited to a small value based on the detected inter-vehicle distance, an effect that a large change in acceleration / deceleration can be suppressed and an uncomfortable feeling given to the driver can be solved.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a first embodiment of the present invention. The inter-vehicle distance sensor 1 as the inter-vehicle distance detecting means is a radar-type detector that emits laser light and receives reflected light from the preceding vehicle. The inter-vehicle distance L to the preceding vehicle and the relative speed ΔV between the preceding vehicle and Is detected.
[0008]
Here, the relative speed ΔV is obtained by differentiating the inter-vehicle distance L, or the inter-vehicle distance L is obtained by hand-pass filtering. The inter-vehicle distance sensor 1 is not limited to the case where laser light is used, and the relative speed may be calculated by detecting the inter-vehicle distance using radio waves or ultrasonic waves. The relative speed ΔV is a value obtained by subtracting the own vehicle speed from the vehicle speed of the preceding vehicle, and is a positive value when the vehicle is separated from the preceding vehicle, and a negative value when the vehicle approaches the preceding vehicle.
[0009]
The vehicle speed sensor 2 detects the output shaft rotation speed of the transmission and converts it to the vehicle speed V.
The preceding vehicle follow-up control controller 3 comprises a microcomputer and its peripheral portion, and a vehicle speed command value V that follows the preceding vehicle based on the input inter-vehicle distance L, vehicle speed V, and the like.^*Is calculated. Details of the preceding vehicle follow-up control controller 3 will be described later.
[0010]
The vehicle speed control unit 4 determines that the actual vehicle speed V is the vehicle speed command value V.^*Driving force command value F that matches^*And the throttle actuator 5, the automatic brake actuator 6, and the transmission actuator 7 are controlled. Various control methods such as a feedback control method and a robust model matching method disclosed in JP-A-10-272963 can be applied to the vehicle speed control unit 4.
[0011]
The throttle actuator 5 has a driving force command value F^*The throttle valve opening of the engine is adjusted according to the throttle valve opening command according to the engine. Further, the automatic brake actuator 6 has a driving force command value F^*The brake fluid pressure is adjusted according to the brake fluid pressure command corresponding to Further, the transmission actuator 7 has a driving force command value F^*The transmission gear ratio is adjusted according to the transmission gear ratio command. The transmission may be a stepped transmission or a continuously variable transmission.
[0012]
In this embodiment, the vehicle speed command value V from the preceding vehicle follow-up control controller 3^*And the transmission characteristic Gv (s) of the vehicle speed control system that outputs the own vehicle speed V detected by the vehicle speed sensor 2 is approximated to a first-order lag system as shown in the following equation.
Gv (s) = ω_V/ (S + ω_V(1)
In this equation (1), ω_VIs the corner frequency of the vehicle speed control unit transmission characteristics.
[0013]
As shown in FIG. 1, the preceding vehicle following control controller 3 includes an inter-vehicle distance command value calculation unit 31 configured by a microcomputer software form, a target inter-vehicle distance calculation constant determination unit 32, and a target inter-vehicle distance setting unit. Target vehicle distance calculation unit 33, vehicle speed command value calculation unit 34 as command value calculation means, pre-compensation vehicle speed command value calculation unit 35, correction vehicle speed command value calculation unit 36, and speed change rate limiting means as A corrected vehicle speed command value change rate limiting unit 37 is provided.
[0014]
Here, in order to simplify the description, a basic configuration excluding the front compensation vehicle speed command value calculation unit 35, the corrected vehicle speed command value calculation unit 36, and the corrected vehicle speed command value change rate limiting unit 37 will be described.
The preceding vehicle follow-up control controller 3 receives an inter-vehicle distance L and a relative speed ΔV from the inter-vehicle distance sensor 1 and an own vehicle speed V from the vehicle speed sensor 2.
[0015]
When the preceding vehicle is detected by the inter-vehicle distance sensor 1, the inter-vehicle distance command value calculation unit 31 is based on the own vehicle speed V and the relative speed ΔV according to the following equation (2), and the inter-vehicle distance command value L^*Is calculated.
L^*= A · Vt + L_OF     (2)
Where a is a coefficient and L_OFIs an offset value when the vehicle is stopped. Vt is the preceding vehicle speed, and is calculated by a value V + ΔV obtained by adding the relative speed ΔV to the host vehicle speed V.
[0016]
The target inter-vehicle distance calculation constant determination unit 32 receives the inter-vehicle distance command value L from the inter-vehicle distance command value calculation unit 31.^*In the inter-vehicle distance control system that outputs the actual inter-vehicle distance L detected by the inter-vehicle distance sensor 1, the actual inter-vehicle distance L is the inter-vehicle distance command value L.^*The response characteristic of the inter-vehicle distance control until reaching the vehicle distance is calculated from the inter-vehicle distance L to the inter-vehicle distance command value L.^*The inter-vehicle distance deviation ΔL (= L−L calculated by subtracting^*) And the relative speed ΔV to obtain an optimum response characteristic (hereinafter referred to as a target inter-vehicle distance control response characteristic), the damping coefficient ζ of the inter-vehicle distance control system_TAnd the natural frequency ω_TIs determined according to the inter-vehicle distance deviation ΔL and the relative speed ΔV.
[0017]
Specifically, the attenuation coefficient ζ of the inter-vehicle distance control system according to the inter-vehicle distance deviation ΔL and the relative speed ΔV so that the optimal response characteristic of inter-vehicle distance control can be obtained in various following scenes._TAnd the natural frequency ω_TIs set in advance as a map, and the damping coefficient ζ corresponding to the inter-vehicle distance deviation ΔL and the relative speed ΔV during the follow-up control._TAnd the natural frequency ω_TIs determined as a target inter-vehicle distance calculation constant. Where the damping coefficient ζ_TAnd natural frequency ω_TFor example, a map described in Japanese Patent Application Laid-Open No. 2000-135934 can be applied.
[0018]
The target inter-vehicle distance calculation unit 33 is an attenuation coefficient ζ for setting the response characteristic in the inter-vehicle distance control system as the target response characteristic._TAnd the natural frequency ω_TIs used to determine the vehicle distance command value L^*The target inter-vehicle distance L through a filter of the secondary form shown in the following equation (3)_TAnd target relative speed ΔV_TIs calculated. The inter-vehicle distance L immediately after the preceding vehicle is recognized₀And relative speed ΔV₀Is the initial value.
[0019]
[Expression 1]

[0020]
That is, the target inter-vehicle distance L calculated by the above equation (3)._TAnd target relative speed ΔV_TIndicates that the actual inter-vehicle distance L passes through the target response characteristic and the inter-vehicle distance command value L^*Is the final inter-vehicle distance command value that defines the temporal transition of the inter-vehicle distance and the relative speed so as to converge.
If this equation (3) is expanded and Laplace transformed, it can be expressed as the following equation (4).
[0021]
[Expression 2]

[0022]
This equation (4) is the inter-vehicle distance command value L^*Target vehicle distance L to_TThe transfer function is expressed by a quadratic equation. In this embodiment, in the inter-vehicle distance control system, the actual inter-vehicle distance L is expressed by the equation (4)._TFeedback control is performed so that the final inter-vehicle distance command value is obtained. As described above, the damping coefficient ζ of the inter-vehicle distance control system_TAnd the natural frequency ω_TIn addition, since a value for obtaining a target inter-vehicle distance control response corresponding to the inter-vehicle distance deviation ΔL and the relative speed ΔV is set, a desirable inter-vehicle distance control response can be realized in various following scenes.
[0023]
As a target inter-vehicle distance control response, even when the inter-vehicle distance with the preceding vehicle is less than the command value in an interruption scene or overtaking scene, when the relative speed with the preceding vehicle is small, a sudden deceleration is not performed. A response is desired so that the actual inter-vehicle distance converges slowly to the command value. Also, in an approaching scene or the like, it is desirable that the response is such that the actual inter-vehicle distance slowly converges to the command value without sudden deceleration when the inter-vehicle distance is long even when the relative speed is large. In such a follow-up scene, the actual inter-vehicle distance has a secondary response characteristic that converges after overshooting or undershooting the command value, and such a response is expressed by the above equations (3) and (4). It can be realized by a secondary filter.
[0024]
The vehicle speed command value calculation unit 34 has a predetermined constant f_VAnd f_LVehicle speed command value V by calculating according to the following equation (5) using^*Is calculated.

In this equation (5), f_VIs the target relative speed deviation (target relative speed ΔV_Tdifference between (t) and relative speed detection value ΔV (t)) {ΔV_Ta constant multiplied by (t) −ΔV (t)}, f_LIs the target inter-vehicle distance deviation (target inter-vehicle distance L_TDifference between (t) and distance detected value L (t)) {L_T(t) −L (t)} is a constant multiplied.
[0025]
In this way, the actual inter-vehicle distance L indicates the target inter-vehicle distance response characteristic._TIn a feedback control system that performs feedback control so that it converges to, the trade-off is that the control gain of the inter-vehicle distance control system must be increased and the control time constant must be shortened in order to increase responsiveness. There is an off relationship.
Therefore, a feedforward loop is added to the inter-vehicle distance feedback control system, and the inter-vehicle distance command value L^*Compensation vehicle speed command value V to obtain the target inter-vehicle distance response from_CThe compensation vehicle speed command value V_CVehicle speed command value V obtained in the inter-vehicle distance control system^*Correct. Therefore, in order to improve the responsiveness without impairing the stability in the inter-vehicle distance control system, the preceding vehicle follow-up controller 3 is added with the front compensation vehicle speed command value calculation unit 35 and the corrected vehicle speed command value calculation unit 36. Yes. Further, a corrected vehicle speed command value change rate limiting unit 37 for limiting the change rate of the corrected vehicle speed command value calculated by the corrected vehicle speed command value calculating unit 36 is also added.
[0026]
The pre-compensation vehicle speed command value calculation unit 35 is a basic inter-vehicle distance command value L^*Through the filter expressed by the following equation (6)_CIs calculated.
[0027]
[Equation 3]

[0028]
The filter of this formula (6) is a vehicle speed command value V^*To the actual inter-vehicle distance L and the product of the inverse system of the transfer function and the target inter-vehicle distance control response characteristic expressed by the above equation (4). Here, the vehicle speed command value V^*To the actual vehicle distance L is the vehicle speed command value V^*, And the difference between the actual vehicle speed V and the preceding vehicle speed Vt, that is, the relative speed ΔV, is integrated. It is expressed by a product with an integrator for obtaining the actual inter-vehicle distance L. The compensation vehicle speed command value V is calculated by the above equation (6)._CThe initial value when calculating is the inter-vehicle distance L immediately after the preceding vehicle is recognized.₀And relative speed ΔV₀And
[0029]
The corrected vehicle speed command value calculation unit 36 calculates the vehicle speed command value V calculated by the inter-vehicle distance control system as shown in the following equation (7).^*To compensated vehicle speed command value V_CThe value (V^*-V_C ) Or the vehicle speed setting value V set by the passenger_SETThe smaller value of the corrected vehicle speed command value V^*And output to the corrected vehicle speed command value change rate limiting unit 37. If the preceding vehicle cannot be captured by the inter-vehicle distance sensor 1, the vehicle speed setting value V set as the target vehicle speed by the occupant_SETIs the corrected vehicle speed command value V^*'Become.
[0030]
V^*'= Min (V^*-V_C, V_SET(7)
The corrected vehicle speed command value change rate limiting unit 37 is configured to correct the above-described corrected vehicle speed command value V.^*The rate of change is limited to 'and the final corrected vehicle speed command value V^*'' Is calculated and output to the vehicle speed control unit 4 described above.
The corrected vehicle speed command value change rate limiting unit 37 executes the vehicle speed command value change rate limiting process shown in FIG. 2 every predetermined time (for example, 10 msec). In addition,_(n) Is the value calculated in this process,_(n-1) Represents the values calculated in the previous process, especially_(n)Or_(n-1) For variables that are not clearly indicated, this value is shown.
[0031]
In the command value change rate limiting process, first, in step S1, it is determined whether there is a preceding vehicle that can be captured by the inter-vehicle distance sensor 1, and if there is no preceding vehicle, the process proceeds to step S2.
In this step S2, a capture flag F representing the capture status of the preceding vehicle._CIt is determined whether or not the vehicle has been reset to “0” representing the situation where the preceding vehicle is not captured. This determination result is the capture flag F_CWhen = 1, it was determined that the preceding vehicle was lost in the previous processing stage, but the preceding vehicle was lost, and the process proceeds to step S3.
[0032]
In this step S3, the timer T that starts counting when the preceding vehicle is lost is cleared to “0”, and in the subsequent step S4, the capture flag F is cleared._CIs reset to "0" and then the process proceeds to step S5.
In this step S5, in order to maintain the vehicle speed V when the preceding vehicle is lost, the final corrected vehicle speed command value V calculated in the previous process is used.^*''_(n-1)Again this final corrected vehicle speed command value V^*''_(n)Is output to the vehicle speed control unit 4 and the process returns to step S1.
[0033]
On the other hand, the determination result of step S2 is the capture flag F._CWhen = 0, it is determined that the state of losing sight of the preceding vehicle is continued, the process proceeds to step S6, and the timer T counted in the previous processing stage_(n-1)After incrementing “1”, the process proceeds to step S7.
In this step S7, the timer T that has started counting after losing sight of the preceding vehicle is set to a predetermined value T₁It is determined whether or not this is the case. This determination result is T <T₁If it is, it is determined that the loss of the preceding vehicle may be temporary, and the process proceeds to step S5. On the other hand, the determination result is T ≧ T₁If it is, it is determined that there is a possibility that the preceding vehicle suitable for the follow-up running has been lost, and the routine proceeds to step S8.
In this step S8, the corrected vehicle speed command value V^*Vehicle speed change rate limit value V to limit 'change rate'^* _RATESwitching flag F for switching the setting method_SIs reset to “0”, and then the process proceeds to step S15 to be described later.
[0034]
On the other hand, when it is determined in step S1 that there is a preceding vehicle, the process proceeds to step S9, where the capture flag F_CIs set to “1”. This determination result is the capture flag F_CWhen = 0, it is determined that the preceding vehicle has started to be captured, and the capture flag F is determined in step S10._CIs set to "1" and then the process proceeds to step S11.
[0035]
In step S11, the relative vehicle speed ΔV immediately after the preceding vehicle is captured.₀And inter-vehicle distance deviation ΔL₀After reading, the process proceeds to step S12 and then to step S13. In these steps S12 and S13, the preceding vehicle captured by the host vehicle follows within a predetermined range including the target inter-vehicle distance, that is, the target inter-vehicle distance L._TIt is determined whether or not the vehicle is in a steady follow-up running state in which the most is maintained.
[0036]
First, in step S12, the relative vehicle speed ΔV read in step S11.₀Is -ΔV_THAnd ΔV_THIt is determined whether or not it is within the second setting range of less than, and this determination result is −ΔV_TH<ΔV₀<ΔV_THIf it is, it is determined that the vehicle is traveling at a speed substantially equal to the captured preceding vehicle, and the process proceeds to step S13.
In step S13, the inter-vehicle distance deviation ΔL read in step S11.₀Is -ΔL_THAnd ΔL_THIt is determined whether it is within a second predetermined range of less than. This determination result is -ΔL_TH<ΔL₀<ΔL_THIs the target inter-vehicle distance L relative to the captured preceding vehicle_TAnd the switch flag F is determined in step S14._SIs set to “1” indicating that the vehicle is in the steady following running state, and then the process proceeds to step S15 described later.
[0037]
On the other hand, the determination result of step S12 is ΔV.₀≤ -ΔV_THOr ΔV₀≧ ΔV_THWhen it is, it is determined that there is a tendency to approach or separate from the preceding vehicle, and the switching flag F_SThe process proceeds to step S15 while resetting “0” to “0”. Further, the determination result of step S13 is ΔL.₀≤ -ΔL_THOr ΔL₀≧ ΔL_THIs equal to the target inter-vehicle distance L_TSwitch flag F_SThe process proceeds to step S15 while resetting “0” to “0”. Further, the determination result of step S9 is the capture flag F._CWhen = 1, it is determined that the preceding vehicle is still being captured, and the process proceeds to step S15.
[0038]
In step S15, the switching flag F_SIs set to “1”, and the result of this determination is the switching flag F_SWhen = 0, the actual inter-vehicle distance L with respect to the preceding vehicle is the target inter-vehicle distance L_TIt is determined that there is a tendency to move away from the vehicle, or that there is a possibility that the vehicle is not in the steady following running state, and the process proceeds to step S16.
In this step S16, the current corrected vehicle speed command value V^*'_(n)Is the last corrected vehicle speed command value V^*''_(n-1)It is determined whether or not it is greater than this, and this determination result is V^*'_(n)> V^*''_(n-1)If it is, it is determined that the host vehicle accelerates, and the process proceeds to step S17. In this step S17, the corrected vehicle speed command value V^*Vehicle speed change rate limit value V that limits the rate of change of '^* _RATEIs the acceleration vehicle speed change rate limit value V as a normal limit value.^* _RATE-AThen, the process proceeds to step S20 described later.
[0039]
On the other hand, the determination result of step S17 is V^*'_(n)≦ V^*''_(n-1)If it is, it is determined whether the host vehicle maintains the vehicle speed or decelerates, and the process proceeds to step S18. In this step S18, the vehicle speed change rate limit value V^* _RATEIs the vehicle speed change rate limit value V for deceleration as the normal limit value.^* _RATE-DThen, the process proceeds to step S20 described later.
[0040]
The determination result in step S15 is the switching flag F._S= 1, the target inter-vehicle distance L with respect to the preceding vehicle captured by the host vehicle_TIs maintained in a steady follow-up running state, and the process proceeds to step S19.
In step S19, the relative vehicle speed ΔV read in step S11.₀And inter-vehicle distance deviation ΔL₀Based on the basic limit value V^* _RATE-BAnd limit value correction constant K_RATEIs calculated, and then the vehicle speed change rate limit value V is calculated based on the following equation (8).^* _RATEThen, the process proceeds to step S20 described later.
[0041]
V^* _RATE= V^* _RATE-B× K_RATE        (8)
Here, the basic limit value V^* _RATE-BIs a relative vehicle speed ΔV as shown in FIG.₀And vehicle speed change rate basic limit value V^* _RATE-BReferring to the basic limit value calculation control map showing the relationship between₀Calculate from This basic limit value calculation control map is stored in advance in a memory included in the preceding vehicle follow-up control controller 3.
[0042]
As shown in FIG. 3, the basic limit value calculation control map has a relative vehicle speed ΔV on the horizontal axis.₀On the vertical axis, the basic limit value V^* _RATE-BIt is expressed in a coordinate system that takes And relative vehicle speed ΔV₀Is the acceleration side limit value ΔV as the first setting range from zero to the positive direction_ACCIn proportion to this, the basic limit value V^* _RATE-BThe positive limit value V^* _RATE-B1To positive steady value V^* _RATE-AIncreases linearly until the relative vehicle speed ΔV₀Is the acceleration limit value ΔV_ACCWhen this is the case, the basic limit value V^* _RATE-BIs V^* _RATE-AIs set to maintain. On the other hand, relative vehicle speed ΔV₀Is the deceleration limit value ΔV as the first setting range from zero to the negative direction_DECBasic limit value V^* _RATE-BIs proportional to the negative limit value V^* _RATE-B2To negative steady value V^* _RATE-DUntil the relative vehicle speed ΔV₀Is the deceleration limit value ΔV_DECBasic limit value V when^* _RATE-BIs V^* _RATE-DIs set to maintain.
[0043]
Furthermore, relative vehicle speed ΔV₀Limit value V when the vehicle changes in the direction approaching the preceding vehicle^* _RATE-BThe basic limit value V when the absolute value of the vehicle changes in a direction away from the preceding vehicle^* _RATE-BV on the acceleration side so that the value is larger than the absolute value of^* _RATE-B1And V^* _RATE-A, And V on the deceleration side^* _RATE-B2And V^* _RATE-DAre set respectively. The acceleration side limit value ΔV_ACCAnd deceleration side limit value ΔV_DECEach of the above-mentioned -ΔV_THExceeds ΔV_THIt is a value within the setting range of less than.
[0044]
Limit value correction constant K_RATEAs shown in FIG. 4, the inter-vehicle distance deviation ΔL₀And limit value correction constant K_RATEReferring to the control map for calculating the limit value correction constant that expresses the relationship between₀Calculate from The limit value correction constant calculation control map is stored in advance in a memory included in the preceding vehicle follow-up control controller 3.
As shown in FIG. 4, this limit value correction constant calculation control map has an inter-vehicle distance deviation ΔL on the horizontal axis.₀, And the vertical axis is the limit value correction constant K_RATEIt is expressed in a coordinate system that takes
And the inter-vehicle distance deviation ΔL₀Is zero, the limit value correction constant K_RATE Is smaller than “1”_RATE-MINFrom this state, the inter-vehicle distance deviation ΔL₀Is the acceleration limit value ΔL as the first predetermined range in the positive direction_ACCLimit value correction constant K when increasing to_RATEIs proportional to K_RATE-MINExceeds 1 and increases linearly to “1”, and the inter-vehicle distance deviation ΔL₀Is the acceleration limit value ΔL_ACCWhen this is the case, the limit value correction constant K_RATEIs set to maintain “1”. On the other hand, the inter-vehicle distance deviation ΔL₀Is the deceleration-side limit value ΔL as the first predetermined range from zero to the negative direction_DECLimit value correction constant K when decreasing to_RATEIs proportional to K_RATE-MINExceeds 1 and increases linearly to “1”, and the inter-vehicle distance deviation ΔL₀Is negative deceleration side limit value ΔL_DECLimit value correction constant K when_RATEIs set to maintain “1”.
[0045]
Furthermore, the inter-vehicle distance deviation ΔL₀Limit value correction constant K when changes in the direction in which the inter-vehicle distance L becomes shorter_RATE Is the limit value correction constant K when the inter-vehicle distance L changes in the direction of increasing._RATEThe acceleration side limit value ΔL so that it becomes a large value compared to_ACCAnd deceleration side limit value ΔL_DECAre set respectively. The acceleration limit value ΔL_ACCAnd deceleration side limit value ΔL_DECEach of the above-mentioned -ΔL_THExceeds ΔL_THIt is a value within a predetermined range of less than.
[0046]
In step S20, the last final corrected vehicle speed command value V^*''_(n-1)To the current corrected vehicle speed command value V^*'_(n)The absolute value of the deviation after subtracting is the vehicle speed change rate limit value V^* _RATEIt is determined whether or not it is larger. This determination result is | V^*''_(n-1)-V^*'_(n)| ≦ | V^* _RATEWhen ||^*'_(n)It is determined that there is no need to limit the process, and the process proceeds to step S21. In this step S21, the switching flag F_SIs reset to “0”, and in the following step S22, the current corrected vehicle speed command value V^*'_(n)The final corrected vehicle speed command value V^*''_(n)Is output to the vehicle speed command unit 4 and the process returns to step S1.
[0047]
On the other hand, the determination result of step S20 is | V^*''_(n-1)-V^*'_(n)｜ ＞ ｜ V^* _RATEWhen |, the previous final corrected vehicle speed command value V^*''_(n-1)To the current corrected vehicle speed command value V^*'_(n)It is determined that the amount of change in vehicle speed is large, and the process proceeds to step S23. In this step S23, the last final corrected vehicle speed command value V^*''_(n-1)Vehicle speed change rate limit value V^* _RATEIs added to the final corrected vehicle speed command value V^*''_(n)Is output to the vehicle speed control unit 4 and the process returns to step S1.
[0048]
Here, the inter-vehicle distance sensor 1 corresponds to the inter-vehicle distance detection means, the target inter-vehicle distance calculation unit 33 in the preceding vehicle following control controller 3 corresponds to the target inter-vehicle distance setting means, and the vehicle speed command value calculation in the preceding vehicle following control controller 3 occurs. The unit 34 corresponds to the command value calculation means, and the vehicle speed control unit 4, the throttle actuator 5, the automatic brake actuator 6 and the transmission actuator 7 correspond to the own vehicle speed control means, and step S9 in the vehicle speed command value change rate limiting process of FIG. , Step S11, Step S12 and Step S13 correspond to the acquisition start follow-up determination means, and Step S15, Step S19, Step S20 and Step S23 in the vehicle speed command value change rate limiting process of FIG. Corresponds to the limiting means.
[0049]
Next, the operation in the above embodiment will be described.
Now, assume that the host vehicle is traveling on a straight flat road in a state where a preceding vehicle suitable for following traveling is captured by the inter-vehicle distance sensor 1. At this time, first, the relative speed ΔV is calculated from the inter-vehicle distance L with respect to the preceding vehicle detected by the inter-vehicle distance sensor 1, and the above equation (2) is calculated from the relative vehicle speed ΔV and the own vehicle speed V detected by the vehicle speed sensor 2. Based on the vehicle distance command value L^*Is calculated.
[0050]
This inter-vehicle distance command value L^*Based on the target inter-vehicle distance calculation unit 33, the target inter-vehicle distance L_TIs output to the vehicle speed command value calculation unit 34, and the target vehicle distance L to which the vehicle speed command value calculation unit 34 is input is calculated._TVehicle speed command value V according to^*Is output to the corrected vehicle speed command value calculator 36. Subsequently, the corrected vehicle speed command value calculation unit 36 receives the input vehicle speed command value V^*To the compensation vehicle speed command value V supplied from the front compensation vehicle speed command value calculation unit 35_CIs subtracted to correct vehicle speed command value V^*By calculating ', the stability in the inter-vehicle distance control system is secured and the response is improved.
[0051]
Further, the corrected vehicle speed command value V^*'Is passed through the corrected vehicle speed command value change rate limiting unit 37 to limit the change rate, and then the final corrected vehicle speed command value V^*'' Is generated. And this final corrected vehicle speed command value V^*”Is supplied to the vehicle speed control unit, and the driving force command value F is obtained by the robust model matching method.^*And the driving force command value F^*By controlling the throttle actuator 5, the automatic brake actuator 6 and the transmission actuator 7 based on the above, the actual inter-vehicle distance L detected by the inter-vehicle distance sensor 1 becomes the target inter-vehicle distance L._TThe vehicle speed control is performed so that it converges to.
[0052]
Thus, the inter-vehicle distance command value L with respect to the preceding vehicle where the host vehicle is traveling at a substantially constant speed.^*When the vehicle is in an ideal following traveling state while maintaining the vehicle speed V, the vehicle speed V substantially matches the vehicle speed Vt of the preceding vehicle, and the relative vehicle speed ΔV is approximately 0 [km as shown in FIG. / H].
Here, the corrected vehicle speed command value V calculated according to the fluctuation of the inter-vehicle distance^*'Is corrected by the corrected vehicle speed command value change rate limiting unit 37. When the vehicle is in an ideal follow-up state for the preceding vehicle, the corrected vehicle speed command value V^*'_(n)The change rate of the vehicle is also sufficiently low, and the previous final corrected vehicle speed command value V has already been^*''_(n-1)To the current corrected vehicle speed command value V^*'_(n)The absolute value of the deviation minus the vehicle speed is the vehicle speed change rate limit value V^* _RATE(The determination in step S20 is “No”), and the switching flag F_CHas been reset to "0" (step S21). Therefore, the corrected vehicle speed command value V^*'Is limited by the normal limit value (determination in step S15 is "No").
[0053]
That is, the current corrected vehicle speed command value V^*'_(n)Is the last corrected vehicle speed command value V^*''_(n-1)On the other hand, when it increases, the vehicle speed change rate limit value V for acceleration^* _RATE-AIn the following (step S17), when decreasing, the vehicle speed change rate limit value V for deceleration is reduced.^* _RATE-DThe corrected vehicle speed command value V is set so as to be as follows (step S18).^*'_(n)By limiting the rate of change of the vehicle, excessive acceleration / deceleration is suppressed during follow-up traveling to the preceding vehicle. This deceleration vehicle speed change rate limit value V^* _RATE-DIs the acceleration vehicle speed change rate limit value V^* _RATE-ATherefore, a larger vehicle speed change rate is allowed during deceleration than during acceleration.
[0054]
Here, for example, when approaching an uphill with a steep slope or a curve with a large curvature from a straight flat road, as shown in FIG.₀Thus, the preceding vehicle is temporarily lost (the determination in step S2 is “No”).
Therefore, the preceding vehicle follow-up control controller 3 determines when the preceding vehicle is lost.₀In order to start the count of the timer T from the beginning, in order to maintain the vehicle speed at the time of losing sight of the preceding vehicle, the final corrected vehicle speed command value V generated in the previous processing stage^*''_(n-1)(Hereafter, lost vehicle speed command value V^*''_LIs continuously output to the vehicle speed control unit 4 (step S5). This lost speed vehicle speed command value V^*''_LThe preceding vehicle is not captured and the timer T is set to a predetermined value T₁If it is less than the value, it is continuously output (determination in step S7 is “No”).
[0055]
Then, the preceding vehicle is still not captured, and as shown in FIG.₁The timer T is a predetermined value T₁When this is the case (the determination in step S7 is “Yes”), the vehicle speed command value V^*''_LInstead of the vehicle speed setting value V set in advance by the driver._SETIs the corrected vehicle speed command value V^*Is output as'.
At this time, the vehicle speed set value V_SETCorrected vehicle speed command value V corresponding to^*'Is lost, vehicle speed command value V^*''_LWhen the vehicle is shifted to the acceleration state, the difference is the acceleration vehicle speed change rate limit value V.^* _RATE-AWhen it is below, the corrected vehicle speed command value V^*'Is the final corrected vehicle speed command value V^*''_(n)Is output to the vehicle speed control unit 4 (step S22).
On the other hand, the corrected vehicle speed command value V^*'When lost and vehicle speed command value V^*''_LIs the vehicle speed change rate limit value V for acceleration.^* _RATE-AWhen the vehicle speed exceeds the vehicle speed command value V^*''_LAcceleration vehicle speed change rate limit value V^* _RATE-AIs the final corrected vehicle speed command value V^*''_(n)Is output to the vehicle speed control unit 4 (step S23).
[0056]
Therefore, as shown in FIG.₂Subsequent final corrected vehicle speed command value V^*''_(n)(Hereinafter simply referred to as vehicle speed command value V^*The vehicle speed V is the vehicle speed setting value V^*Until reaching '' Acceleration vehicle speed change rate limit value V^* _RATE-AIt gradually increases while being limited to the following rate of change. And in response to this, the driving force command value F shown in FIG.^*The vehicle gradually accelerates by gradually increasing the value.
[0057]
Then, the host vehicle exits the vicinity of the top of the uphill with a steep slope or a curve with a large curvature, and the time t in FIG.₂As shown by, it is assumed that the inter-vehicle distance sensor 1 has captured the preceding vehicle again (determination in step S9 is “No”).
First, the preceding vehicle follow-up control controller 3 captures the preceding vehicle at time t.₂Vehicle speed relative to the preceding vehicle at₀And inter-vehicle distance deviation ΔL₀Is read (step S11). Next, these relative vehicle speeds ΔV₀Is within the setting range (−ΔV_TH<ΔV₀<ΔV_TH) And inter-vehicle distance deviation ΔL₀ Is within a predetermined range (−ΔL_TH<ΔL₀ <ΔL_TH) (Step S12 and step S13), and the target inter-vehicle distance L with respect to the preceding vehicle recaptured by the host vehicle_TIt is confirmed whether or not the vehicle is in a steady follow-up running state in which it is mostly maintained.
[0058]
If the preceding vehicle is decelerating or accelerating while losing sight of the preceding vehicle and re-captured by the inter-vehicle distance sensor 1, the relative vehicle speed ΔV₀Is -ΔV_THOr ΔV_THThis is the above (the determination in step S12 is “No”), or the inter-vehicle distance deviation ΔL₀Is -ΔL_THOr ΔL_THIf this is the case (determination in step S13 is “No”), that is, if the vehicle deviates from the steady following running state, it is necessary to allow relatively large acceleration / deceleration. Therefore, the corrected vehicle speed command value V calculated after the preceding vehicle is captured again.^*The change rate of 'is the normal limit value for the acceleration speed change rate limit value V^* _RATE-AOr vehicle speed change rate limit value V for deceleration^* _RATE-DBy limiting to the following (step S17 or step S18), while suppressing rapid acceleration / deceleration, the target inter-vehicle distance L_TTo quickly converge to
[0059]
On the other hand, the time t when the preceding vehicle is recaptured₂As shown in FIG. 5C, the relative vehicle speed ΔV₀Is -ΔV_THExceeds ΔV_THWithin the set range of less than (determination of step S12 is “Yes”), and as shown in FIG. 5A, the difference of the actually measured inter-vehicle distance with respect to the target inter-vehicle distance (inter-vehicle distance deviation ΔL₀) Is -ΔL_THExceeds ΔL_THIf the vehicle is in a steady following traveling state with respect to the preceding vehicle, that is, the relatively large acceleration / deceleration is not necessarily required as described above. Don't be.
[0060]
Here, at time t in FIG.₂Thereafter, the original corrected vehicle speed command value V indicated by the one-point difference line^*Vehicle speed command value V when 'is limited by the normal limit value described above^*'' Indicates an excessive change rate as indicated by a dotted line, but still, this vehicle speed command value V^*Driving force command value F corresponding to ''^*As shown by the dotted line in FIG. 5D, the rate of change is relatively large and discontinuous.
[0061]
Therefore, when the host vehicle is in a steady following traveling state with respect to the preceding vehicle, the target inter-vehicle distance L_TIt is desirable that the further convergence to be more delicate. Therefore, the corrected vehicle speed command value V calculated after the preceding vehicle is captured again.^*The rate of change of 'when the preceding vehicle is captured t₂Relative vehicle speed ΔV₀And inter-vehicle distance deviation ΔL₀Based on the vehicle speed change rate limit value V so as to be smaller than the normal limit value^* _RATEIs calculated (step S19).
[0062]
Therefore, for example, relative vehicle speed ΔV₀Is the deceleration side limit value ΔV from zero_DECIf the value is less than the basic limit value V^* _RATE-BThe absolute value of V is V^* _RATE-DThe value is smaller than the absolute value of. Furthermore, the inter-vehicle distance deviation ΔL₀Is the deceleration limit value ΔL from zero_DECWhen the value is less than the limit value correction constant K_RATEHowever, the value is smaller than “1”.
[0063]
Thus, the basic limit value V^* _RATE-BLimit value correction constant K_RATEVehicle speed change rate limit value V calculated by multiplying by^* _RATEBecomes smaller than the normal limit value, so that time t in FIG.₂As indicated by the solid line below, the corrected vehicle speed command value V^*Limit the rate of change to even smaller. As a result, as shown by the solid line in FIG. 5D, a continuous driving force command value F that moderately suppresses a relatively large change.^*By outputting, the uncomfortable feeling that can be given to the driver is surely suppressed.
[0064]
After that, the actual inter-vehicle distance L with the preceding vehicle becomes the target inter-vehicle distance L_TAs the vehicle gradually converges, the calculated corrected vehicle speed command value V^*'_(n)The rate of change will gradually decrease. And the last final corrected vehicle speed command value V^*''_(n-1)To the current corrected vehicle speed command value V^*'_(n)The absolute value of the deviation minus the vehicle speed is the vehicle speed change rate limit value V^* _RATEAfter the absolute value becomes less than (the determination in step S20 is “No”), the vehicle speed change rate limit value V^* _RATEReturns to the normal limit value (step S21).
[0065]
In addition, a timer T that starts counting after losing sight of the preceding vehicle is set to a predetermined value T₁When the preceding vehicle is captured again when the vehicle speed is less than the vehicle speed command value V^*''_LIs continuously output, there is a high possibility that the vehicle is in a steady follow-up running state with respect to the preceding vehicle.
Then, when it is confirmed that the vehicle is in a steady follow-up running state with respect to the preceding vehicle (the determinations in steps S12 and S13 are “Yes” together), the target inter-vehicle distance L_TIn order to perform further convergence on the vehicle more delicately, the corrected vehicle speed command value V^*The rate of change of 'when the preceding vehicle is captured t₂Relative vehicle speed ΔV₀And inter-vehicle distance deviation ΔL₀Based on the vehicle speed change rate limit value V so as to be smaller than the normal limit value^* _RATEIs calculated (step S19). If the preceding vehicle is suddenly decelerating or accelerating for a short time while losing sight of the preceding vehicle, and deviates from the steady following running state (determination of either step S12 or step S13 is “ No ”), to allow a relatively large acceleration / deceleration, the corrected vehicle speed command value V^*The rate of change of 'is limited by the normal limit value (step S17 or step S18).
[0066]
In addition, a case will be described in which a preceding vehicle is lost due to a nose dive caused by braking control when the vehicle is following the preceding vehicle. Note that this braking control is extremely temporary.
Therefore, when the vehicle posture is immediately rebuilt and the preceding vehicle is followed, even if the time for losing sight of the preceding vehicle is short, the steady follow-up to the preceding vehicle is caused by a braking control that causes a nose dive to lose sight of the preceding vehicle. The possibility of being in a running state is low.
[0067]
Therefore, when the vehicle actually deviates from the steady following traveling state for the preceding vehicle (the determination in either step S12 or step S13 is “No”), relatively large acceleration / deceleration is permitted (step S17 or step S17). S18). If the preceding vehicle is decelerated in the same manner as the host vehicle while losing sight of the preceding vehicle and is captured again, the target inter-vehicle distance L_TFurther convergence to is performed more delicately (step S19).
[0068]
In the basic limit value calculation control map of FIG. 3 in the first embodiment, the relative vehicle speed ΔV₀Is the deceleration limit value ΔV_DECTo acceleration side limit value ΔV_ACCWhen changing within the setting range, the basic limit value V^* _RATE-BAlthough the configuration in which is linearly changed has been described, the present invention is not limited to this. That is, relative vehicle speed ΔV₀The basic limit value V according to the fluctuation of^* _RATE-BMay change in a curved line or may change in a plurality of stages.
[0069]
In the basic limit value calculation control map of FIG. 3 in the first embodiment, the relative vehicle speed ΔV₀Is zero, the basic limit value V^* _RATE-BIs V on the deceleration side^* _RATE-B2However, the present invention is not limited to this.^* _RATE-B1You may set so that.
Furthermore, in the control map for calculating the limit value correction constant of FIG. 4 in the first embodiment, the inter-vehicle distance deviation ΔL₀Is the deceleration limit value ΔL_DECTo acceleration side limit value ΔL_ACCThe limit value correction constant K accordingly_RATEAlthough the configuration in which is linearly changed has been described, the present invention is not limited to this. That is, the inter-vehicle distance deviation ΔL₀Limit value correction constant K according to the fluctuation of_RATEMay change in a curved line or may change in a plurality of stages.
[0070]
Furthermore, in the first embodiment, the inter-vehicle distance command value calculation unit 31 determines the inter-vehicle distance command value L based on the preceding vehicle speed Vt.^*Although the case of calculating is described, it is not limited to this. That is, the vehicle speed Vt is applied instead of the preceding vehicle speed Vt, and the inter-vehicle distance command value L is expressed as shown in the following equation (9).^*May be calculated as a function of the vehicle speed V.
[0071]
L^*= A '· V + L_OF'... (9)
Here, a ′ is a coefficient, L_OF'Is the offset value when the vehicle is stopped.
Furthermore, as shown in FIG. 6, a preset inter-vehicle distance setting value L_SETThe inter-vehicle distance command value L^*As a result, the inter-vehicle distance command value calculation unit 31 may be omitted, or the front compensation vehicle speed command value calculation unit 35 and the corrected vehicle speed command value calculation unit 36 may be omitted.
[0072]
Further, in the first embodiment, the rate of change of the vehicle speed command value is set to the vehicle speed command value limit V.^* _RATEHowever, the present invention is not limited to this. That is, the driving force command value F calculated by the vehicle speed control unit 4^*The rate of change of the vehicle speed may be limited. In short, it is only necessary that the rate of change of the vehicle speed can be limited.
As described above, when it is determined that the host vehicle when the preceding vehicle starts to be captured by the inter-vehicle distance detection sensor 1 is in a steady follow-up running state in which the preceding vehicle follows the preceding vehicle within a predetermined range including the target inter-vehicle distance. Based on the inter-vehicle distance L detected by the inter-vehicle distance sensor 1, the corrected vehicle speed command value V^*The change rate of 'is smaller than the normal limit value.^* _RATEBy restricting with, a large change in acceleration / deceleration can be reliably suppressed, and the uncomfortable feeling given to the driver can be resolved.
[0073]
Also, relative vehicle speed ΔV with the preceding vehicle₀And inter-vehicle distance L and target inter-vehicle distance L_TDistance between vehicles ΔL₀To detect relative vehicle speed ΔV₀ΔV as the first setting range including zero_DECAnd ΔV_ACCOr less than or equal to the vehicle distance deviation ΔL₀ΔL as in the first predetermined range including zero_DECAnd ΔL_ACCIs less than the corrected vehicle speed command value V^*The change rate of 'is smaller than the normal limit value.^* _RATETherefore, a large change in acceleration / deceleration can be accurately suppressed, and the uncomfortable feeling given to the driver can be resolved.
[0074]
Further, when the preceding vehicle is started to be captured by the inter-vehicle distance sensor 1, the relative vehicle speed ΔV₀-ΔV as in the second setting range including zero_THAnd ΔV_THIs less than and the inter-vehicle distance deviation ΔL₀-ΔL as in the second predetermined range including zero_TH And ΔL_THWhen it is less than the value, it is determined that the vehicle is in the steady follow-up traveling state, and therefore it is possible to accurately determine whether or not the host vehicle largely maintains the target inter-vehicle distance from the preceding vehicle.
[0075]
Furthermore, relative vehicle speed ΔV₀, Or inter-vehicle distance deviation ΔL₀As each of these approaches zero, the vehicle speed change rate limit value V^* _RATEIs set to a small value, a large change in acceleration / deceleration can be suppressed more accurately, and the uncomfortable feeling given to the driver can be eliminated.
Also, relative vehicle speed ΔV₀Speed change rate limit value V when the vehicle changes in the direction approaching the preceding vehicle^* _RATEVehicle speed change rate limit value V when changing in a direction away from the preceding vehicle^* _RATETherefore, safety can be improved by allowing a larger vehicle speed change rate when decelerating than when accelerating.
[0076]
Furthermore, the inter-vehicle distance deviation ΔL₀Vehicle speed change rate limit value V when the distance changes in the direction of decreasing the inter-vehicle distance^* _RATEIs the vehicle speed change rate limit value V when the inter-vehicle distance L changes in the longer direction.^* _RATETherefore, safety can be improved by allowing a larger vehicle speed change rate when decelerating than when accelerating.
[0077]
Furthermore, the change rate of the vehicle speed command value calculated by the vehicle speed command value calculation unit 34 is set to the vehicle speed change rate limit value V.^* _RATEBy restricting with, the speed change rate of the host vehicle can be easily restricted.
Next, a second embodiment of the present invention will be described with reference to FIG.
In the second embodiment, the vehicle speed change rate limit value V in the first embodiment described above is used.^* _RATEThe calculation method is changed.
[0078]
That is, in the second embodiment, as shown in FIG. 7 for the vehicle speed command value change rate limiting process executed by the preceding vehicle follow-up control controller 3, the process of step S19 in FIG. V^* _RATEIs the basic limit value V^* _RATE-BExcept for the fact that it is changed to step S30 that is calculated based only on the above, the processing procedure is the same as that of the first embodiment, so the corresponding parts to those in FIG. This is omitted from the description.
[0079]
Therefore, for example, when the vehicle is in a steady following running state with respect to a preceding vehicle re-captured by the host vehicle ("Yes" in step S12 and step S13), the relative vehicle speed ΔV₀Is over zero and the deceleration limit value ΔV_DECWhen it is less than the basic limit value V^* _RATE-BThe absolute value of V is usually V^* _RATE-DThe value is smaller than the absolute value of. Also, relative vehicle speed ΔV₀Is over zero and the acceleration side limit value ΔV_ACCWhen it is less than the basic limit value V^* _RATE-BThe absolute value of V is usually V^* _RATE-AThe value is smaller than the absolute value of.
[0080]
In the second embodiment, the relative vehicle speed ΔV₀Based on the basic limit value V^* _RATE-BAlthough the structure which calculates is described, it is not limited to this. That is, for example, referring to a control map having the same characteristics as the limit value correction constant calculation control map of FIG. 4 described above, the relative vehicle speed ΔV₀To limit value correction constant K_RATEIs calculated, and this is set to a preset basic limit value V^* _RATE-RThe vehicle speed change rate limit value V^* _RATEThe important point is that the relative vehicle speed ΔV₀Vehicle speed change rate limit value V^* _RATEAny calculation method may be used as long as it can be reduced.
[0081]
As described above, relative vehicle speed ΔV with the preceding vehicle₀To detect relative vehicle speed ΔV₀ΔV as the first setting range including zero_DECAnd ΔV_ACCIs less than the corrected vehicle speed command value V^*The change rate of 'is smaller than the normal limit value.^* _RATETherefore, a large change in acceleration / deceleration can be easily suppressed, and the uncomfortable feeling given to the driver can be resolved.
[0082]
Next, a third embodiment of the present invention will be described with reference to FIG.
This third embodiment is a vehicle speed change rate limit value V in the first embodiment described above.^* _RATEThe calculation method is changed.
That is, in the third embodiment, as shown in FIG. 7 for the vehicle speed command value change rate limiting process executed by the preceding vehicle following control controller 3, the process of step S19 of FIG. Basic limit value V^* _RATE-RLimit value correction constant K_RATEMultiplied by the vehicle speed change rate limit value V^* _RATE2 except that it is changed to step S31 for calculating the same as in the first embodiment, the same reference numerals are given to the corresponding parts to those in FIG. Is omitted.
[0083]
Incidentally, the fixed basic limit value V^* _RATE-RIs the acceleration vehicle speed change rate limit value V in the first embodiment described above.^* _RATE-AOr vehicle speed change rate limit value V for deceleration^* _RATE-DIt is set to a nearby value.
Therefore, for example, when the host vehicle is in a steady follow-up running state with respect to the preceding vehicle that has been captured again (the determination result of step S12 and step S13 is “Yes” together), the inter-vehicle distance deviation ΔL₀Is over zero and the deceleration limit value ΔL_DECLimit value correction constant K when less than_RATE Is smaller than “1”. Also, the inter-vehicle distance deviation ΔL₀Exceeds zero and the acceleration limit value ΔL_ACCLimit value correction constant K when less than_RATE Is smaller than “1”. Thus, the limit correction constant K_RATE Is constant basic limit value V^* _RATE-RIs normally multiplied by V as a limit value.^* _RATE-DThe value is smaller than the absolute value of.
[0084]
In the third embodiment, the inter-vehicle distance deviation ΔL₀To limit value correction constant K_RATE Although the structure which calculates is described, it is not limited to this. That is, for example, referring to a control map having the same characteristics as the basic limit value calculation control map of FIG.₀To basic limit value V^* _RATE-BTo calculate the vehicle speed change rate limit value V^* _RATEMay be reduced, the point is that the inter-vehicle distance deviation ΔL₀Vehicle speed change rate limit value V^* _RATEAny calculation method may be used as long as it can be reduced.
[0085]
As described above, the inter-vehicle distance L and the target inter-vehicle distance L_TDistance between vehicles ΔL₀Is detected and the inter-vehicle distance deviation ΔL₀ΔL as in the first predetermined range including zero_DECAnd ΔL_ACCIs less than the corrected vehicle speed command value V^*The change rate of 'is smaller than the normal limit value.^* _RATETherefore, a large change in acceleration / deceleration can be easily suppressed, and the uncomfortable feeling given to the driver can be resolved.
[0086]
Next, a fourth embodiment of the present invention will be described with reference to FIG.
In the fourth embodiment, in the first embodiment described above, the host vehicle may be in a steady running state with respect to the preceding vehicle based on the return time until the preceding vehicle is recovered from the state where the preceding vehicle is not captured. It is configured to predict sex.
That is, in the fourth embodiment, as shown in FIG. 9, the vehicle speed command value change rate limiting process executed by the preceding vehicle follow-up control controller 3 is performed in the flowchart of FIG. 2 in the first embodiment described above. Since the processing procedure is the same as that of the first embodiment except that step S40 is added after processing S10, the same reference numerals are given to the corresponding parts in FIG. Omits this.
[0087]
In the vehicle speed command value change rate limiting process of FIG. 9, the capture flag F is determined in step S10._CIs set to “1”, and then the process proceeds to step S40. In step S40, the time t when the preceding vehicle is lost.₀The timer T that starts counting from the predetermined value T^*Whether it is less than or not is determined. This determination result is T ≧ T^*If it is, it is determined that the possibility that the host vehicle is in a steady running state with respect to the preceding vehicle is low, and the routine proceeds to step S8. On the other hand, the determination result is T <T^*If it is, it is determined that the loss of the preceding vehicle is temporary, and the process proceeds to step S11. The predetermined value T^*Is the target inter-vehicle distance L relative to the preceding vehicle_TTherefore, the predetermined value is set to be relatively long.
[0088]
Therefore, for example, when a preceding vehicle suitable for following driving is lost due to a change in the lane of the preceding vehicle, and then a new preceding vehicle is captured after a certain amount of time, the timer T that has started counting after losing sight of the preceding vehicle Predetermined value T^*When this is the case (the determination in step S40 is “No”), the possibility that the host vehicle is in a steady running state with respect to the preceding vehicle is low. Therefore, in order to allow a relatively large acceleration / deceleration, a corrected vehicle speed command value V calculated after the preceding vehicle is captured again.^*The change rate of 'is the normal limit value for the acceleration speed change rate limit value V^* _RATE-AOr vehicle speed change rate limit value V for deceleration^* _RATE-DBy limiting to the following (step S17 or step S18), while suppressing rapid acceleration / deceleration, the target inter-vehicle distance L_TTo quickly converge to
[0089]
On the other hand, the timer T has a predetermined value T^*If it is less than that (determination of step S40 is “Yes”), it is determined that the loss of the preceding vehicle is temporary, and whether or not the own vehicle is actually in a steady running state with respect to the preceding vehicle. The determination is made (step S12 and step S13).
As described above, the timer T until the vehicle distance sensor 1 returns from the state in which the preceding vehicle is not captured to the state in which the preceding vehicle is captured is a predetermined value T^*When it is less than the threshold value, the vehicle speed change rate is limited to a small value based on the inter-vehicle distance L, and the timer T is set to a predetermined value T^*When it is above, it is configured to limit the vehicle speed change rate using the normal limit value, so if the losing time of the preceding vehicle is long, the determination process of steady following traveling at the start of acquisition is omitted. Thus, the vehicle speed command value change rate limiting process can be simplified.
[0090]
In the fourth embodiment, as in the first embodiment described above, the relative vehicle speed ΔV₀And inter-vehicle distance deviation ΔL₀Vehicle speed change rate limit value V^* _RATEAlthough the structure which calculates is described, it is not limited to this. That is, as in the second embodiment or the third embodiment described above, the relative vehicle speed ΔV₀Or inter-vehicle distance deviation ΔL₀Vehicle speed change rate limit value V based on^* _RATEMay be calculated.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention.
FIG. 2 is a flowchart showing an example of a vehicle speed command value change rate limiting process in the first embodiment.
FIG. 3 is a basic limit value calculation control map;
FIG. 4 is a control map for calculating a limit value correction constant.
FIG. 5 is a time chart for explaining the operation of the first embodiment.
6 is a schematic configuration diagram when an inter-vehicle distance command value calculation unit 31, a pre-compensation vehicle speed command value calculation unit 35, and a corrected vehicle speed command value calculation unit 36 are omitted. FIG.
FIG. 7 is a flowchart showing an example of a vehicle speed command value change rate limiting process in the second embodiment.
FIG. 8 is a flowchart showing an example of a vehicle speed command value change rate limiting process in the third embodiment.
FIG. 9 is a flowchart showing an example of a vehicle speed command value change rate limiting process in the fourth embodiment.
[Explanation of symbols]
1 Inter-vehicle distance sensor (inter-vehicle distance detection means)
2 Vehicle speed sensor
3 Precedence vehicle follow-up control controller
4 Vehicle speed control unit (own vehicle speed control means)
5 Throttle actuator (Vehicle speed control means)
6 Automatic brake actuator (Vehicle speed control means)
7 Transmission actuator (Vehicle speed control means)
31 Inter-vehicle distance command value calculator
32 Constant Determining Unit for Target Vehicle Distance Calculation
33 Target inter-vehicle distance calculation unit (target inter-vehicle distance setting means)
34 Vehicle speed command value calculation unit (command value calculation means)
35 Precompensation vehicle speed command value calculation unit
36 Corrected vehicle speed command value calculation unit
37 Correction vehicle speed command value change rate limiting unit (speed change rate limiting means)

Claims (10)

When the preceding vehicle is captured by the inter-vehicle distance detecting means for detecting the inter-vehicle distance between the preceding vehicle and the host vehicle, the target inter-vehicle distance setting means for setting the target inter-vehicle distance from the preceding vehicle, and the inter-vehicle distance detecting means. , A command value calculating means for calculating a vehicle speed command value for converging the inter-vehicle distance detected by the inter-vehicle distance detecting means to the target inter-vehicle distance, and the vehicle speed of the host vehicle based on the vehicle speed command value calculated by the command value calculating means. In the inter-vehicle distance control device comprising the own vehicle speed control means for controlling,
The inter-vehicle distance when the vehicle is returned from a state in which the preceding vehicle is not captured by the inter-vehicle distance detecting means to a state in which the preceding vehicle is captured, and when the vehicle is in a steady follow-up running state that follows the preceding vehicle within a predetermined range including the target inter-vehicle distance. An inter-vehicle distance control device configured to limit a speed change rate of the own vehicle speed control unit with a limit value smaller than a normal limit value based on an inter-vehicle distance detected by a detection unit. When the preceding vehicle is captured by the inter-vehicle distance detecting means for detecting the inter-vehicle distance between the preceding vehicle and the host vehicle, the target inter-vehicle distance setting means for setting the target inter-vehicle distance from the preceding vehicle, and the inter-vehicle distance detecting means. The vehicle speed command value for converging the inter-vehicle distance detected by the inter-vehicle distance detection means to the target inter-vehicle distance is calculated, and when the preceding vehicle is not captured by the inter-vehicle distance detection means, the preset vehicle speed setting value is set as the vehicle speed. In an inter-vehicle distance control device comprising command value calculation means as a command value and own vehicle speed control means for controlling the vehicle speed of the host vehicle based on the vehicle speed command value calculated by the command value calculation means,
Follow-up tracking at the time of start of catching to determine whether the host vehicle when the preceding-vehicle distance detection means starts capturing the preceding vehicle is in a steady-following traveling state following the preceding vehicle within a predetermined range including the target inter-vehicle distance. When it is determined by the determination means and the acquisition start time tracking determination means that the host vehicle is in a steady following running state, the speed change rate of the host vehicle speed control means is determined based on the inter-vehicle distance detected by the inter-vehicle distance detection means. An inter-vehicle distance control device comprising speed change rate limiting means for limiting with a limit value smaller than a normal limit value. Relative vehicle speed detecting means for detecting a relative vehicle speed with respect to the preceding vehicle, or an inter-vehicle distance deviation detecting means for detecting an inter-vehicle distance deviation between the inter-vehicle distance and a target inter-vehicle distance, and the speed change rate limiting means When the relative vehicle speed detected by the relative vehicle speed detecting means is within a first set range including zero, or the inter-vehicle distance deviation detected by the inter-vehicle distance deviation detecting means is within a first predetermined range including zero. 3. The inter-vehicle distance control device according to claim 2, wherein the speed change rate of the vehicle speed control means is limited by a limit value smaller than a normal limit value. Relative vehicle speed detecting means for detecting a relative vehicle speed with respect to the preceding vehicle, and inter-vehicle distance deviation detecting means for detecting an inter-vehicle distance deviation between the inter-vehicle distance and a target inter-vehicle distance, and the speed change rate limiting means, When the relative vehicle speed detected by the relative vehicle speed detecting means is within a first set range including zero, or when the inter-vehicle distance deviation detected by the inter-vehicle distance deviation detecting means is within a first predetermined range including zero. 3. The inter-vehicle distance control device according to claim 2, wherein the speed change rate of the vehicle speed control means is limited by a limit value smaller than a normal limit value. When the capture start time tracking determination unit starts capturing the preceding vehicle by the inter-vehicle distance detection unit, the relative vehicle speed detected by the relative vehicle speed detection unit is within a second set range including zero, and the inter-vehicle distance The inter-vehicle distance according to any one of claims 2 to 4, wherein when the inter-vehicle distance deviation detected by the deviation detecting means is within a second predetermined range including zero, it is determined that the vehicle is in a steady following running state. Distance control device. 6. The speed change rate limiting means is configured to set the limit value to a smaller value as the relative vehicle speed or the inter-vehicle distance deviation approaches zero, respectively. The inter-vehicle distance control device according to any one of the above. The speed change rate limiting means sets the limit value when the relative vehicle speed changes in the direction approaching the preceding vehicle to a larger value than the limit value when the relative vehicle speed changes in the direction away from the preceding vehicle. The inter-vehicle distance control device according to any one of claims 2 to 6, wherein the inter-vehicle distance control device is configured as described above. The speed change rate limiting means sets a limit value when the inter-vehicle distance deviation changes in a direction in which the inter-vehicle distance becomes shorter than a limit value when changes in the direction in which the inter-vehicle distance becomes longer. The inter-vehicle distance control device according to any one of claims 2 to 7, wherein the inter-vehicle distance control device is configured as described above. The speed change rate limiting means limits the vehicle speed change rate to a small value based on the inter-vehicle distance when the return time until the vehicle is detected from the state in which the preceding vehicle is not captured by the inter-vehicle distance detection means is less than a predetermined time. The inter-vehicle distance according to any one of claims 2 to 8, wherein when the return time is equal to or longer than a predetermined time, the vehicle speed change rate is limited using a normal limit value. Control device. The speed change rate limiting means is configured to limit the speed change rate of the own vehicle speed control means by limiting the rate of change of the vehicle speed command value calculated by the command value calculation means. The inter-vehicle distance control device according to any one of 1 to 9.

Images