JP4007769B2

JP4007769B2 - Vehicle tracking control device

Info

Publication number: JP4007769B2
Application number: JP2001095240A
Authority: JP
Inventors: 敏明新井
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2001-03-29
Filing date: 2001-03-29
Publication date: 2007-11-14
Anticipated expiration: 2021-03-29
Also published as: JP2002283875A

Description

【０００１】
【発明の属する技術分野】
本発明は、先行車との間に所定の目標車間距離を置いて先行車に追従走行するための車両用追従走行制御装置に関する。
【０００２】
【従来の技術】
特開平１０−１６６８９４号公報には、自車が追従走行する先行車が急激な加減速を行った場合に、自車は先行車にそのまま追従走行することなく、自車の車速を所定時間一定値に保持したり、ブレーキ制御の制御ゲインを所定時間小さく変更したりすることにより、自車が急激に加減速して乗り心地が損なわれるのを防止する車両用追従走行制御装置が記載されている。
【０００３】
【発明が解決しようとする課題】
しかしながら上記従来のものは、先行車が継続して急加速を行った場合でも自車は目標車速を所定時間保持するので、先行車との相対速度および車間距離が極端に増加してしまい、先行車との車間距離を設定車間距離に復帰させるために通常よりも長い加速時間や加速度が必要となる問題があった。
【０００４】
本発明は前述の事情に鑑みてなされたもので、先行車の加減速状態に応じて自車の追従走行特性を変更し、乗り心地性能および追従性能の両立を図ることを目的とする。
【０００５】
【課題を解決するための手段】
上記目的を達成するために、請求項１に記載された発明によれば、自車速を検知する自車速検知手段と、先行車との車間距離および相対速を検知する先行車検知手段と、自車速に基づいて先行車との目標車間距離を算出する目標車間距離算出手段と、自車速および先行車との相対速に基づいて先行車の車速を算出する先行車車速算出手段と、目標車間距離および先行車の車速に基づいて自車の目標車速を算出する目標車速算出手段と、目標車速に基づいて自車速を制御する自車速制御手段とを備えた車両用追従走行制御装置において、目標車速算出手段が出力する自車の目標車速をフィルタリングするフィルタ手段と、先行車の車速に基づいて先行車の加減速度を算出する先行車加減速度算出手段と、先行車の加減速度に応じてフィルタ手段の特性を変更するフィルタ特性変更手段とを備え、前記フィルタ手段はカットオフ周波数が０．０８Ｈｚから２Ｈｚの間の値となる複数のローパスフイルタから構成され、前記フィルタ特性変更手段は、先行車の加減速度が所定値以上になった場合に、より高いカットオフ周波数を持つローパスフイルタに切り換えることを特徴とする車両用追従走行制御装置が提案される。
【０００６】
上記構成によれば、先行車加減速度算出手段で算出した先行車の加減速度に応じて、自車の目標車速をフィルタリングするフィルタ手段の特性をフィルタ特性変更手段が変更するので、先行車の加減速度の変化に対する自車の目標車速の変化特性を任意に変更し、自車の乗り心地性能および追従性能を両立させることができる。しかも先行車の加減速度が所定値以上になると、フィルタ特性変更手段が、フィルタ手段を構成するカットオフ周波数が０．０８Ｈｚから２Ｈｚの間の値となる複数のローパスフイルタのうち、より高いカットオフ周波数を持つローパスフイルタに切り換えるので、目標車速に対する自車速の応答特性が高くなって先行車に対する追従性能が向上する。逆に先行車の加減速度が所定値未満になると、より低いカットオフ周波数を持つローパスフイルタに切り換えるので、目標車速に対する自車速の応答特性が低くなって乗り心地性能が向上する。
【０００７】
また請求項２に記載された発明によれば、自車速を検知する自車速検知手段と、先行車との車間距離および相対速を検知する先行車検知手段と、自車速に基づいて先行車との目標車間距離を算出する目標車間距離算出手段と、自車速および先行車との相対速に基づいて先行車の車速を算出する先行車車速算出手段と、目標車間距離および先行車の車速に基づいて自車の目標車速を算出する目標車速算出手段と、目標車速に基づいて自車速を制御する自車速制御手段とを備えた車両用追従走行制御装置において、目標車速算出手段が出力する自車の目標車速をフィルタリングするフィルタ手段と、先行車との車間距離に基づいて先行車との追突予測時間を算出する追突予測時間算出手段と、先行車との追突予測時間に応じてフィルタ手段の特性を変更するフィルタ特性変更手段とを備え、前記フィルタ手段はカットオフ周波数が０．０８Ｈｚから２Ｈｚの間の値となる複数のローパスフイルタから構成され、前記フィルタ特性変更手段は、先行車との追突予測時間が所定値以下になった場合に、より高いカットオフ周波数を持つローパスフイルタに切り換えることを特徴とする車両用追従走行制御装置が提案される。
【０００８】
上記構成によれば、追突予測時間算出手段で算出した先行車との追突予測時間に応じて、自車の目標車速をフィルタリングするフィルタ手段の特性をフィルタ特性変更手段で変更するので、先行車との追突予測時間の変化に対する自車の目標車速の変化特性を任意に変更し、自車の乗り心地性能および追従性能を両立させることができる。しかも先行車との衝突予測時間が所定値以下になると、フィルタ特性変更手段が、フィルタ手段を構成するカットオフ周波数が０．０８Ｈｚから２Ｈｚの間の値となる複数のローパスフイルタのうち、より高いカットオフ周波数を持つローパスフイルタに切り換えるので、目標車速に対する自車速の応答特性が高くなって先行車に対する追従性能が向上する。逆に先行車との衝突予測時間が所定値を越えると、より低いカットオフ周波数を持つローパスフイルタに切り換えるので、目標車速に対する自車速の応答特性が低くなって乗り心地性能が向上する。
【０００９】
尚、実施例のレーザーレーダー装置Ｓｔは本発明の先行車検知手段に対応する。
【００１０】
【発明の実施の形態】
以下、本発明の実施の形態を、添付図面に示した本発明の実施例に基づいて説明する。
【００１１】
図１〜図６は本発明の第１実施例を示すもので、図１はレーダー装置のブロック図、図２はレーダー装置の斜視図、図３は車両用追従走行制御装置の構成を示すブロック図、図４はフィルタ手段の特性を示すグラフ、図５は作用を説明するフローチャート、図６はフィルタ手段を通過した目標車速の変化特性を示すグラフである。
【００１２】
図１および図２に示すように、先行車のような自車前方の物体を検知するためのレーザーレーダー装置Ｓｔは本発明の先行車検知手段を構成するもので、送光部１と、送光走査部２と、受光部３と、受光走査部４と、距離計測処理部５とを備える。送光部１は、送光レンズを一体に備えたレーザーダイオード１１と、レーザーダイオード１１を駆動するレーザーダイオード駆動回路１２とを備える。送光走査部２は、レーザーダイオード１１が出力したレーザーを反射させる送光ミラー１３と、送光ミラー１３を上下軸１４回りに往復回動させるモータ１５と、モータ１５の駆動を制御するモータ駆動回路１６とを備える。送光ミラー１３から出る送光ビームは左右幅が制限されて上下方向に細長いパターンを持ち、それが所定周期で左右方向に往復移動して物体を走査する。
【００１３】
受光部３は、受光レンズ１７と、受光レンズ１７で収束させた反射波を受けて電気信号に変換するフォトダイオード１８と、フォトダイオード１８の出力信号を増幅する受光アンプ回路１９とを備える。受光走査部４は、物体からの反射波を反射させて前記フォトダイオード１８に導く受光ミラー２０と、受光ミラー２０を左右軸２１回りに往復回動させるモータ２２と、モータ２２の駆動を制御するモータ駆動回路２３とを備える。上下幅が制限されて左右方向に細長いパターンを持つ受光エリアは、受光ミラー２０によって所定周期で上下方向に往復移動して物体を走査する。
【００１４】
距離計測処理部５は、前記レーザーダイオード駆動回路１２やモータ駆動回路１６，２３を制御する制御回路２４と、全速度領域追従システムを制御する電子制御ユニット２５との間で通信を行う通信回路２６と、レーザーの送光から受光までの時間をカウントするカウンタ回路２７と、物体までの距離および物体の方向を算出する中央演算処理装置２８とを備える。
【００１５】
而して、上下方向に細長い送光ビームと左右方向に細長い受光エリアとが交わる部分が瞬間的な検知エリアになり、この検知エリアは、送光ビームの左右走査幅と等しい左右幅を持ち、受光エリアの上下走査幅と等しい上下幅を持つ検知領域の全域をジグザグに移動して物体を走査する。そして送光ビームが送光されてから、該送光ビームが物体に反射された反射波が受光されるまでの時間に基づいて物体までの距離が検知され、そのときの瞬間的な検知エリアの方向に基づいて物体の方向が検知される。更に、前回の走査で検知した物体までの距離と今回の走査で検知した物体までの距離との差分を走査周期で除算することにより、自車に対する物体の相対速を検知することができる。
【００１６】
図３に示すように、先行車がない場合にはセット車速で定速走行制御を行い、先行車がある場合にはセット車間距離で追従走行制御を行うＡＣＣシステム（アダプティブ・クルーズ・コントロール・システム）の電子制御ユニットＵには、車輪速に基づいて自車速を検知する自車速検知手段Ｓｖからの信号と、前記レーザーレーダー装置Ｓｔ（先行車検知手段）からの信号とが入力される。尚、図示されていないが、ＡＣＣシステムの電子制御ユニットＵには、自車速検知手段Ｓｖおよびレーザーレーダー装置Ｓｔ以外に、メインスイッチ、セットスイッチ、レジュームスイッチ、キャンセルスイッチ、アクセルペダルスイッチ、スロットル開度センサ、ブレーキ油圧センサ等が接続される。
【００１７】
電子制御ユニットＵは、目標車間距離算出手段Ｍ１と、先行車車速算出手段Ｍ２と、目標車速算出手段Ｍ３と、自車速制御手段Ｍ４と、フィルタ手段Ｍ５と、先行車加減速度算出手段Ｍ６と、フィルタ特性変更手段Ｍ７とを備える。
【００１８】
目標車間距離算出手段Ｍ１は、自車速検知手段Ｓｖで検知した自車速に基づいて、追従走行制御を行うための目標車間距離を算出する。目標車間距離は自車速が大きいときに増加し、自車速が小さいときに減少する。先行車車速算出手段Ｍ２は、自車速検知手段Ｓｖで検知した自車速と、レーザーレーダー装置Ｓｔで検知した先行車の相対速とに基づいて先行車車速を算出する。先行車車速は、自車速＋先行車の相対速で与えられる。目標車速算出手段Ｍ３は、目標車間距離算出手段Ｍ１で算出した目標車間距離と、先行車車速算出手段Ｍ２で算出した先行車車速とに基づいて先行車に追従走行するための自車の目標車速を算出する。目標車速は、先行車車速＋距離偏差補正項で与えられ、前記距離偏差補正項は、α×（実車間距離−目標車間距離）で与えられる。ここで、αは状況に応じて変化する係数である。
【００１９】
フィルタ手段Ｍ５は、高周波成分をカットして低周波成分だけをパスさせるローパスフイルタで構成される。図４に示すように、目標車速算出手段Ｍ３からの目標車速信号が入力されるフィルタ手段Ｍ５は、入力周波数が閾値未満の場合にはゲインが一定に保持されるが、入力周波数が前記閾値以上になるとゲインが０に向かってリニアに減少する特性を有している。そして前記閾値は、０．０８Ｈｚから２Ｈｚの範囲で可変である。先行車加減速度算出手段Ｍ６は、先行車車速算出手段Ｍ２で算出した先行車車速を時間微分して先行車の加減速度を算出し、フィルタ特性変更手段Ｍ７は、先行車の加減速度（絶対値）が小さいときには前記閾値を小さい側（０．０８Ｈｚ側）に変更し、先行車の加減速度（絶対値）が大きいときには前記閾値を大きい側（２Ｈｚ側）に変更する。
【００２０】
しかして、自車速制御手段Ｍ４は、フィルタ手段Ｍ５が出力する目標車速に基づいてスロットルやブレーキのアクチュエータＡを作動させ、自車速を目標車速に制御することで実車間距離を目標車間距離に一致させる。
【００２１】
以上のように、先行車が急加速や急減速を行った場合には、フィルタ手段Ｍ５のカットオフ周波数が高い側に変化するので、急加速や急減速を行う先行車に自車を確実に追従させて追従性能を高めることができ、これにより先行車が急加速したときに車間距離が極端に増加したり、先行車が急減速したときに車間距離が極端に減少したりする不具合を回避することができる。逆に、先行車が緩やかに加速や減速を行った場合には、フィルタ手段Ｍ５のカットオフ周波数が低い側に変化するので、先行車の加減速に対する自車の応答性を低くし、自車速の変動を最小限に抑えて乗り心地性能を高めることができる。
【００２２】
上記作用を図５のフローチャートに基づいて説明する。
【００２３】
先ず、ステップＳ１で現在ＡＣＣシステムによる制御中であるとき、ステップＳ２で先行車が存在し、かつステップＳ３で定速走行制御の設定車速Ｖｍｅｍが追従走行制御の目標車速Ｖａｃｃよりも大きければ、ステップＳ４で先行車の加減速度を算出し、ステップＳ５で前記加減速度に応じたフィルタ設定を選択する。そしてステップＳ６で、前記選択したフィルタ設定が現在のフィルタ設定と異なっていれば、ステップＳ７でフィルタ設定の切替えを行う。尚、前記ステップＳ２で先行車が存在しない場合、あるいは前記ステップＳ３で設定車速Ｖｍｅｍが目標車速Ｖａｃｃ以下の場合には、ステップＳ８で予め設定したフィルタ設定に切替える。
【００２４】
図６には、フィルタ手段Ｍ５を通過した目標車速の変化特性が示される。同図から明らかなように、先行車車速の変化率が小さい領域ではフィルタ手段Ｍ５のカットオフ周波数が低くなるため、目標車速の変化率が小さくなって乗り心地性能が向上する。一方、先行車が急制動を行って先行車車速が急激に低下したときには、フィルタ手段Ｍ５のカットオフ周波数が高くなるため、自車速が先行車車速に速やかに追従して追従性能が向上する。
【００２５】
次に、図７に基づいて本発明の第２実施例を説明する。
【００２６】
第１実施例を示す図３と本第２実施例を示す図７とを比較すると明らかなように、第１実施例の車両用追従走行制御装置が先行車加減速度算出手段Ｍ６を備えているのに対し、本第２実施例の車両用追従走行制御装置は衝突予測時間算出手段Ｍ６′を備えており、その衝突予測時間算出手段Ｍ６′で算出した衝突予測時間に応じてフィルタ特性変更手段Ｍ７がフィルタ手段Ｍ５の特性を変更する。衝突予測時間はレーザーレーダー装置Ｓｔ（先行車検知手段）で検知した先行車との車間距離に基づいて算出されるが、先行車の相対速や自車速を併せて考慮すれば衝突予測時間を更に精度良く算出することができる。
【００２７】
そして衝突予測時間算出手段Ｍ６′で算出した衝突予測時間が長くなるほどフィルタ手段Ｍ５のカットオフ周波数が低くなるため、目標車速の変化率が小さくなって乗り心地性能が向上する。一方、衝突予測時間算出手段Ｍ６′で算出した衝突予測時間が短くなるほどフィルタ手段Ｍ５のカットオフ周波数が高くなるため、自車速が先行車車速に速やかに追従して追従性能が向上する。このように、本第２実施例によっても、乗り心地性能と追従性能とを効果的に両立させることができる。
【００２８】
次に、図８に基づいて本発明の第３実施例を説明する。
【００２９】
図４で説明したように、第１実施例および第２実施例ではフィルタ手段Ｍ５のカットオフ周波数を無段階に（つまり連続的に）変化させていたが、図８に示すように、本実施例ではフィルタ手段Ｍ５のカットオフ周波数を先行車加減速度あるいは衝突予測時間に応じて段階的に（つまり不連続に）に変化させるようになっている。この場合、フィルタ手段Ｍ５のカットオフ周波数を切り替えるときのノイズを防止するために、前回の選択されていたフィルタの出力値を用いて新たに選択されたフィルタの出力値を初期化する必要がある。
【００３０】
以上、本発明の実施例を説明したが、本発明はその要旨を逸脱しない範囲で種々の設計変更を行うことが可能である。
【００３１】
例えば、実施例で先行車検知装置としてレーザーレーダー装置Ｓｔを例示したが、レーザーレーダー装置Ｓｔに代えてミリ波レーダー装置を用いることができる。
【００３２】
【発明の効果】
以上のように請求項１に記載された発明によれば、先行車加減速度算出手段で算出した先行車の加減速度に応じて、自車の目標車速をフィルタリングするフィルタ手段の特性をフィルタ特性変更手段が変更するので、先行車の加減速度の変化に対する自車の目標車速の変化特性を任意に変更し、自車の乗り心地性能および追従性能を両立させることができる。しかも先行車の加減速度が所定値以上になると、フィルタ特性変更手段が、フィルタ手段を構成するカットオフ周波数が０．０８Ｈｚから２Ｈｚの間の値となる複数のローパスフイルタのうち、より高いカットオフ周波数を持つローパスフイルタに切り換えるので、目標車速に対する自車速の応答特性が高くなって先行車に対する追従性能が向上する。逆に先行車の加減速度が所定値未満になると、より低いカットオフ周波数を持つローパスフイルタに切り換えるので、目標車速に対する自車速の応答特性が低くなって乗り心地性能が向上する。
【００３３】
また請求項２に記載された発明によれば、追突予測時間算出手段で算出した先行車との追突予測時間に応じて、自車の目標車速をフィルタリングするフィルタ手段の特性をフィルタ特性変更手段で変更するので、先行車との追突予測時間の変化に対する自車の目標車速の変化特性を任意に変更し、自車の乗り心地性能および追従性能を両立させることができる。しかも先行車との衝突予測時間が所定値以下になると、フィルタ特性変更手段が、フィルタ手段を構成するカットオフ周波数が０．０８Ｈｚから２Ｈｚの間の値となる複数のローパスフイルタのうち、より高いカットオフ周波数を持つローパスフイルタに切り換えるので、目標車速に対する自車速の応答特性が高くなって先行車に対する追従性能が向上する。逆に先行車との衝突予測時間が所定値を越えると、より低いカットオフ周波数を持つローパスフイルタに切り換えるので、目標車速に対する自車速の応答特性が低くなって乗り心地性能が向上する。
【図面の簡単な説明】
【図１】レーダー装置の全体構成を示すブロック図
【図２】レーダー装置の斜視図
【図３】車両用追従走行制御装置の構成を示すブロック図
【図４】フィルタ手段の特性を示すグラフ
【図５】作用を説明するフローチャート
【図６】フィルタ手段を通過した目標車速の変化特性を示すグラフ
【図７】本発明の第２実施例に係る車両用追従走行制御装置の構成を示すブロック図
【図８】本発明の第３実施例に係るフィルタ手段を示す図
【符号の説明】
Ｍ１目標車間距離算出手段
Ｍ２先行車車速算出手段
Ｍ３目標車速算出手段
Ｍ４自車速制御手段
Ｍ５フィルタ手段
Ｍ６先行車加減速度算出手段
Ｍ６′ 追突予測時間算出手段
Ｍ７フィルタ特性変更手段
Ｓｖ自車速検知手段
Ｓｔレーダー装置（先行車検知手段）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle follow-up travel control device for following a preceding vehicle with a predetermined target inter-vehicle distance from the preceding vehicle.
[0002]
[Prior art]
In Japanese Patent Laid-Open No. 10-166894, when a preceding vehicle that the vehicle follows is suddenly accelerated and decelerated, the vehicle does not follow the preceding vehicle as it is and the vehicle speed of the vehicle is constant for a predetermined time. A vehicle follow-up travel control device is described that prevents the host vehicle from suddenly accelerating or decelerating and losing the ride comfort by maintaining the value or changing the control gain of the brake control small for a predetermined time. Yes.
[0003]
[Problems to be solved by the invention]
However, in the above-mentioned conventional vehicle, even if the preceding vehicle continuously accelerates rapidly, the host vehicle maintains the target vehicle speed for a predetermined time, so that the relative speed and the inter-vehicle distance with the preceding vehicle increase extremely, and the preceding vehicle In order to return the inter-vehicle distance to the set inter-vehicle distance, there is a problem that acceleration time and acceleration longer than usual are required.
[0004]
The present invention has been made in view of the above circumstances, and an object of the present invention is to change the following traveling characteristic of the own vehicle in accordance with the acceleration / deceleration state of the preceding vehicle and to achieve both riding comfort performance and following performance.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the invention described in claim 1, the vehicle speed detecting means for detecting the vehicle speed, the preceding vehicle detecting means for detecting the inter-vehicle distance and the relative speed with the preceding vehicle, Target inter-vehicle distance calculating means for calculating the target inter-vehicle distance from the preceding vehicle based on the vehicle speed, preceding vehicle speed calculating means for calculating the vehicle speed of the preceding vehicle based on the host vehicle speed and the relative speed with the preceding vehicle, and the target inter-vehicle distance. In the vehicle follow-up travel control device, the target vehicle speed includes a target vehicle speed calculation unit that calculates the target vehicle speed of the host vehicle based on the vehicle speed of the preceding vehicle, and a host vehicle speed control unit that controls the host vehicle speed based on the target vehicle speed. Filter means for filtering the target vehicle speed output from the calculation means, preceding vehicle acceleration / deceleration calculation means for calculating the acceleration / deceleration of the preceding vehicle based on the vehicle speed of the preceding vehicle, and filter means according to the acceleration / deceleration of the preceding vehicle And a filter characteristic changing means for changing the characteristics, the filter means is composed of a plurality of low-pass filter becomes a value between 2Hz cutoff frequency from 0.08 Hz, the filter characteristic changing means, the preceding vehicle acceleration A vehicle follow-up travel control device is proposed, which switches to a low-pass filter having a higher cut-off frequency when the speed exceeds a predetermined value .
[0006]
According to the above configuration, the filter characteristic changing unit changes the characteristic of the filter unit that filters the target vehicle speed of the own vehicle according to the acceleration / deceleration of the preceding vehicle calculated by the preceding vehicle acceleration / deceleration calculating unit. The change characteristic of the target vehicle speed of the own vehicle with respect to the change of the speed can be arbitrarily changed, and both the riding comfort performance and the following performance of the own vehicle can be achieved. Moreover, when the acceleration / deceleration of the preceding vehicle exceeds a predetermined value, the filter characteristic changing means has a higher cutoff value among a plurality of low-pass filters having a cutoff frequency between 0.08 Hz and 2 Hz constituting the filter means. Since the low-pass filter having the frequency is switched, the response characteristic of the own vehicle speed with respect to the target vehicle speed is enhanced, and the follow-up performance with respect to the preceding vehicle is improved. Conversely, when the acceleration / deceleration of the preceding vehicle is less than the predetermined value, the low-pass filter having a lower cutoff frequency is switched, so that the response characteristic of the own vehicle speed with respect to the target vehicle speed is lowered and the riding comfort performance is improved.
[0007]
According to the invention described in claim 2 , the own vehicle speed detecting means for detecting the own vehicle speed, the preceding vehicle detecting means for detecting the inter-vehicle distance and the relative speed with the preceding vehicle, the preceding vehicle based on the own vehicle speed, Based on the target inter-vehicle distance calculating means for calculating the target inter-vehicle distance, the preceding vehicle speed calculating means for calculating the vehicle speed of the preceding vehicle based on the own vehicle speed and the relative speed with the preceding vehicle, and the target inter-vehicle distance and the vehicle speed of the preceding vehicle. In the vehicle follow-up travel control device comprising target vehicle speed calculation means for calculating the target vehicle speed of the host vehicle and host vehicle speed control means for controlling the host vehicle speed based on the target vehicle speed, the host vehicle output by the target vehicle speed calculation means Filter means for filtering the target vehicle speed of the vehicle, a collision prediction time calculation means for calculating a collision prediction time with the preceding vehicle based on the inter-vehicle distance from the preceding vehicle, and characteristics of the filter means according to the collision prediction time with the preceding vehicle And a filter characteristic changing means for changing the filter means is composed of a plurality of low-pass filter becomes a value between 2Hz cutoff frequency from 0.08 Hz, the filter characteristic changing means, collision prediction to the preceding vehicle A vehicle follow-up travel control device is proposed that switches to a low-pass filter having a higher cut-off frequency when the time falls below a predetermined value .
[0008]
According to the above configuration, the characteristic of the filter means for filtering the target vehicle speed of the own vehicle is changed by the filter characteristic changing means according to the predicted collision time with the preceding vehicle calculated by the predicted collision time calculating means. The change characteristic of the target vehicle speed of the own vehicle with respect to the change in the predicted rear-end collision time can be arbitrarily changed, and both the riding comfort performance and the follow-up performance of the own vehicle can be achieved. In addition, when the predicted collision time with the preceding vehicle is less than or equal to the predetermined value, the filter characteristic changing unit is higher among the plurality of low-pass filters in which the cutoff frequency constituting the filter unit is a value between 0.08 Hz and 2 Hz. Since the low-pass filter having the cut-off frequency is switched, the response characteristic of the own vehicle speed with respect to the target vehicle speed is enhanced, and the follow-up performance with respect to the preceding vehicle is improved. On the other hand, when the predicted collision time with the preceding vehicle exceeds a predetermined value, switching to a low-pass filter having a lower cut-off frequency results in lower response characteristics of the host vehicle speed with respect to the target vehicle speed and improved ride comfort performance.
[0009]
The laser radar device St of the embodiment corresponds to the preceding vehicle detection means of the present invention.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0011]
1 to 6 show a first embodiment of the present invention. FIG. 1 is a block diagram of a radar device, FIG. 2 is a perspective view of the radar device, and FIG. 3 is a block diagram showing the configuration of a vehicle tracking control device. FIG. 4 is a graph showing the characteristics of the filter means, FIG. 5 is a flowchart for explaining the operation, and FIG. 6 is a graph showing the change characteristics of the target vehicle speed that has passed through the filter means.
[0012]
As shown in FIG. 1 and FIG. 2, a laser radar device St for detecting an object ahead of the host vehicle such as a preceding vehicle constitutes a preceding vehicle detecting means of the present invention. An optical scanning unit 2, a light receiving unit 3, a light receiving scanning unit 4, and a distance measurement processing unit 5 are provided. The light transmission unit 1 includes a laser diode 11 integrally provided with a light transmission lens, and a laser diode drive circuit 12 that drives the laser diode 11. The light transmission scanning unit 2 includes a light transmission mirror 13 that reflects the laser output from the laser diode 11, a motor 15 that reciprocates the light transmission mirror 13 about the vertical axis 14, and a motor drive that controls the driving of the motor 15. Circuit 16. The light transmission beam emitted from the light transmission mirror 13 is limited in the left-right width and has an elongated pattern in the vertical direction, which reciprocates in the left-right direction in a predetermined cycle to scan the object.
[0013]
The light receiving unit 3 includes a light receiving lens 17, a photodiode 18 that receives a reflected wave converged by the light receiving lens 17 and converts it into an electrical signal, and a light receiving amplifier circuit 19 that amplifies an output signal of the photodiode 18. The light receiving scanning unit 4 controls the driving of the light receiving mirror 20 that reflects the reflected wave from the object and guides it to the photodiode 18, the motor 22 that reciprocates the light receiving mirror 20 around the left and right axis 21, and the driving of the motor 22. And a motor drive circuit 23. The light receiving area having a vertically narrowed pattern with a narrow vertical width is scanned back and forth in the vertical direction by the light receiving mirror 20 in a predetermined cycle.
[0014]
The distance measurement processing unit 5 communicates between the control circuit 24 that controls the laser diode drive circuit 12 and the motor drive circuits 16 and 23 and the electronic control unit 25 that controls the full speed region following system. And a counter circuit 27 that counts the time from laser transmission to reception, and a central processing unit 28 that calculates the distance to the object and the direction of the object.
[0015]
Thus, the portion where the light transmission area elongated in the vertical direction and the light receiving area elongated in the left-right direction becomes an instantaneous detection area, and this detection area has a horizontal width equal to the horizontal scanning width of the light transmission beam, The entire detection area having the vertical width equal to the vertical scanning width of the light receiving area is moved zigzag to scan the object. The distance to the object is detected based on the time from when the light transmission beam is transmitted to when the reflected wave reflected by the object is received, and the instantaneous detection area at that time is detected. The direction of the object is detected based on the direction. Further, by dividing the difference between the distance to the object detected in the previous scan and the distance to the object detected in the current scan by the scan period, the relative speed of the object with respect to the host vehicle can be detected.
[0016]
As shown in FIG. 3, an ACC system (adaptive cruise control system) that performs constant speed running control at the set vehicle speed when there is no preceding vehicle, and performs follow-up running control at the set inter-vehicle distance when there is a preceding vehicle. The electronic control unit U) receives a signal from the vehicle speed detection means Sv for detecting the vehicle speed based on the wheel speed and a signal from the laser radar device St (preceding vehicle detection means). Although not shown, the electronic control unit U of the ACC system includes a main switch, a set switch, a resume switch, a cancel switch, an accelerator pedal switch, a throttle opening, in addition to the own vehicle speed detection means Sv and the laser radar device St. A sensor, a brake hydraulic pressure sensor, and the like are connected.
[0017]
The electronic control unit U includes a target inter-vehicle distance calculation means M1, a preceding vehicle speed calculation means M2, a target vehicle speed calculation means M3, a host vehicle speed control means M4, a filter means M5, a preceding vehicle acceleration / deceleration calculation means M6, Filter characteristic changing means M7.
[0018]
The target inter-vehicle distance calculating means M1 calculates a target inter-vehicle distance for performing the follow-up running control based on the own vehicle speed detected by the own vehicle speed detecting means Sv. The target inter-vehicle distance increases when the host vehicle speed is high, and decreases when the host vehicle speed is low. The preceding vehicle speed calculation means M2 calculates the preceding vehicle speed based on the own vehicle speed detected by the own vehicle speed detection means Sv and the relative speed of the preceding vehicle detected by the laser radar device St. The preceding vehicle speed is given by the own vehicle speed + the relative speed of the preceding vehicle. The target vehicle speed calculating means M3 is a target vehicle speed for following the preceding vehicle based on the target inter-vehicle distance calculated by the target inter-vehicle distance calculating means M1 and the preceding vehicle speed calculated by the preceding vehicle speed calculating means M2. Is calculated. The target vehicle speed is given by the preceding vehicle speed + distance deviation correction term, and the distance deviation correction term is given by α × (actual inter-vehicle distance−target inter-vehicle distance). Here, α is a coefficient that changes depending on the situation.
[0019]
The filter means M5 is composed of a low-pass filter that cuts high-frequency components and passes only low-frequency components. As shown in FIG. 4, the filter means M5 to which the target vehicle speed signal from the target vehicle speed calculation means M3 is input has a constant gain when the input frequency is less than the threshold, but the input frequency is not less than the threshold. Then, the gain linearly decreases toward zero. The threshold value is variable in the range of 0.08 Hz to 2 Hz. The preceding vehicle acceleration / deceleration calculating means M6 calculates the acceleration / deceleration of the preceding vehicle by differentiating the preceding vehicle speed calculated by the preceding vehicle speed calculating means M2 with respect to time, and the filter characteristic changing means M7 calculates the acceleration / deceleration (absolute value) of the preceding vehicle. ) Is small, the threshold value is changed to the smaller side (0.08 Hz side), and when the acceleration / deceleration (absolute value) of the preceding vehicle is large, the threshold value is changed to the larger side (2 Hz side).
[0020]
Accordingly, the own vehicle speed control means M4 operates the throttle or brake actuator A based on the target vehicle speed output from the filter means M5, and controls the own vehicle speed to the target vehicle speed, thereby matching the actual inter-vehicle distance with the target inter-vehicle distance. Let
[0021]
As described above, when the preceding vehicle suddenly accelerates or decelerates, the cut-off frequency of the filter means M5 changes to the higher side. The following performance can be improved by following the vehicle, which avoids the problem that the distance between the vehicles increases drastically when the preceding vehicle suddenly accelerates or the distance between the vehicles decreases drastically when the preceding vehicle suddenly decelerates. can do. Conversely, when the preceding vehicle slowly accelerates or decelerates, the cut-off frequency of the filter means M5 changes to the lower side, so that the response of the own vehicle to acceleration / deceleration of the preceding vehicle is lowered, and the own vehicle speed is reduced. The ride performance can be improved by minimizing fluctuations.
[0022]
The above operation will be described with reference to the flowchart of FIG.
[0023]
First, when the control by the ACC system is currently being performed in step S1, if there is a preceding vehicle in step S2, and if the set vehicle speed Vmem for constant speed traveling control is greater than the target vehicle speed Vacc for following traveling control in step S3, step In step S4, the acceleration / deceleration of the preceding vehicle is calculated. In step S5, a filter setting corresponding to the acceleration / deceleration is selected. In step S6, if the selected filter setting is different from the current filter setting, the filter setting is switched in step S7. If no preceding vehicle is present in step S2 or if the set vehicle speed Vmem is equal to or lower than the target vehicle speed Vacc in step S3, the filter setting is changed to a preset filter in step S8.
[0024]
FIG. 6 shows a change characteristic of the target vehicle speed that has passed through the filter means M5. As is clear from the figure, since the cutoff frequency of the filter means M5 is low in the region where the change rate of the preceding vehicle speed is small, the change rate of the target vehicle speed is reduced and the riding comfort performance is improved. On the other hand, when the preceding vehicle suddenly brakes and the preceding vehicle speed rapidly decreases, the cutoff frequency of the filter means M5 increases, so that the own vehicle speed quickly follows the preceding vehicle speed and the follow-up performance is improved.
[0025]
Next, a second embodiment of the present invention will be described with reference to FIG.
[0026]
As is apparent from a comparison between FIG. 3 showing the first embodiment and FIG. 7 showing the second embodiment, the vehicle follow-up travel control device of the first embodiment includes a preceding vehicle acceleration / deceleration calculation means M6. On the other hand, the vehicle follow-up travel control apparatus of the second embodiment includes a collision prediction time calculation unit M6 ′, and a filter characteristic changing unit according to the collision prediction time calculated by the collision prediction time calculation unit M6 ′. M7 changes the characteristics of the filter means M5. The predicted collision time is calculated based on the inter-vehicle distance from the preceding vehicle detected by the laser radar device St (preceding vehicle detection means). If the relative speed of the preceding vehicle and the vehicle speed are taken into account, the estimated collision time is further increased. It is possible to calculate with high accuracy.
[0027]
As the collision prediction time calculated by the collision prediction time calculation means M6 ′ becomes longer, the cutoff frequency of the filter means M5 becomes lower, so that the rate of change of the target vehicle speed becomes smaller and the riding comfort performance improves. On the other hand, as the collision prediction time calculated by the collision prediction time calculation means M6 ′ becomes shorter, the cutoff frequency of the filter means M5 becomes higher, so that the own vehicle speed quickly follows the preceding vehicle speed and the follow-up performance is improved. Thus, according to the second embodiment, it is possible to effectively achieve both riding comfort performance and tracking performance.
[0028]
Next, a third embodiment of the present invention will be described with reference to FIG.
[0029]
As described with reference to FIG. 4, in the first embodiment and the second embodiment, the cutoff frequency of the filter means M5 is changed steplessly (that is, continuously). However, as shown in FIG. In the example, the cutoff frequency of the filter means M5 is changed stepwise (that is, discontinuously) in accordance with the preceding vehicle acceleration / deceleration or the predicted collision time. In this case, in order to prevent noise when switching the cut-off frequency of the filter means M5, it is necessary to initialize the output value of the newly selected filter using the output value of the previously selected filter. .
[0030]
Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.
[0031]
For example, the laser radar device St is exemplified as the preceding vehicle detection device in the embodiment, but a millimeter wave radar device can be used instead of the laser radar device St.
[0032]
【The invention's effect】
As described above, according to the first aspect of the present invention, the characteristic of the filter means for filtering the target vehicle speed of the own vehicle is changed according to the acceleration / deceleration of the preceding vehicle calculated by the preceding vehicle acceleration / deceleration calculating means. Since the means is changed, the change characteristic of the target vehicle speed of the own vehicle with respect to the change of the acceleration / deceleration of the preceding vehicle can be arbitrarily changed, and both the riding comfort performance and the following performance of the own vehicle can be achieved. Moreover, when the acceleration / deceleration of the preceding vehicle exceeds a predetermined value, the filter characteristic changing means has a higher cutoff value among a plurality of low-pass filters having a cutoff frequency between 0.08 Hz and 2 Hz constituting the filter means. Since the low-pass filter having the frequency is switched, the response characteristic of the own vehicle speed with respect to the target vehicle speed is enhanced, and the follow-up performance with respect to the preceding vehicle is improved. Conversely, when the acceleration / deceleration of the preceding vehicle is less than the predetermined value, the low-pass filter having a lower cutoff frequency is switched, so that the response characteristic of the own vehicle speed with respect to the target vehicle speed is lowered and the riding comfort performance is improved.
[0033]
According to the invention described in claim 2 , the characteristic of the filter means for filtering the target vehicle speed of the own vehicle is determined by the filter characteristic changing means according to the predicted collision time with the preceding vehicle calculated by the predicted collision time calculation means. Since the change is made, it is possible to arbitrarily change the change characteristic of the target vehicle speed of the own vehicle with respect to the change in the predicted collision time with the preceding vehicle, and to achieve both the riding comfort performance and the follow-up performance of the own vehicle. In addition, when the predicted collision time with the preceding vehicle is less than or equal to the predetermined value, the filter characteristic changing unit is higher among the plurality of low-pass filters in which the cutoff frequency constituting the filter unit is a value between 0.08 Hz and 2 Hz. Since the low-pass filter having the cut-off frequency is switched, the response characteristic of the own vehicle speed with respect to the target vehicle speed is enhanced, and the follow-up performance with respect to the preceding vehicle is improved. On the other hand, when the predicted collision time with the preceding vehicle exceeds a predetermined value, switching to a low-pass filter having a lower cut-off frequency results in lower response characteristics of the host vehicle speed with respect to the target vehicle speed and improved ride comfort performance.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a radar device. FIG. 2 is a perspective view of the radar device. FIG. 3 is a block diagram showing a configuration of a vehicle follow-up control device. FIG. 5 is a flowchart for explaining the operation. FIG. 6 is a graph showing a change characteristic of the target vehicle speed that has passed through the filter means. FIG. 7 is a block diagram showing the configuration of the vehicle follow-up travel control apparatus according to the second embodiment of the invention. FIG. 8 is a diagram showing filter means according to a third embodiment of the present invention.
M1 target inter-vehicle distance calculating means M2 preceding vehicle speed calculating means M3 target vehicle speed calculating means M4 own vehicle speed control means M5 filter means M6 preceding vehicle acceleration / deceleration calculating means M6 ′ rear-end collision prediction time calculating means M7 filter characteristic changing means Sv own vehicle speed detecting means St Radar device (preceding vehicle detection means)

Claims

Own vehicle speed detecting means (Sv) for detecting the own vehicle speed;
Preceding vehicle detection means (St) for detecting the inter-vehicle distance and relative speed with the preceding vehicle;
Target inter-vehicle distance calculation means (M1) for calculating a target inter-vehicle distance from the preceding vehicle based on the own vehicle speed;
Preceding vehicle vehicle speed calculation means (M2) for calculating the vehicle speed of the preceding vehicle based on the host vehicle speed and the relative speed with the preceding vehicle;
Target vehicle speed calculation means (M3) for calculating the target vehicle speed of the host vehicle based on the target inter-vehicle distance and the vehicle speed of the preceding vehicle;
Own vehicle speed control means (M4) for controlling the own vehicle speed based on the target vehicle speed;
In a vehicle follow-up travel control device comprising:
Filter means (M5) for filtering the target vehicle speed of the host vehicle output by the target vehicle speed calculation means (M3);
Preceding vehicle acceleration / deceleration calculating means (M6) for calculating the acceleration / deceleration of the preceding vehicle based on the vehicle speed of the preceding vehicle;
Filter characteristic changing means (M7) for changing the characteristics of the filter means (M5) according to the acceleration / deceleration of the preceding vehicle;
Equipped with a,
The filter means (M5) is composed of a plurality of low-pass filters having a cutoff frequency between 0.08 Hz and 2 Hz,
The vehicle follow-up travel control device, wherein the filter characteristic changing means (M7) switches to a low-pass filter having a higher cut-off frequency when the acceleration / deceleration of the preceding vehicle exceeds a predetermined value .

Own vehicle speed detecting means (Sv) for detecting the own vehicle speed;
Preceding vehicle detection means (St) for detecting the inter-vehicle distance and relative speed with the preceding vehicle;
Target inter-vehicle distance calculation means (M1) for calculating a target inter-vehicle distance from the preceding vehicle based on the own vehicle speed;
Preceding vehicle vehicle speed calculation means (M2) for calculating the vehicle speed of the preceding vehicle based on the host vehicle speed and the relative speed with the preceding vehicle;
Target vehicle speed calculation means (M3) for calculating the target vehicle speed of the host vehicle based on the target inter-vehicle distance and the vehicle speed of the preceding vehicle;
Own vehicle speed control means (M4) for controlling the own vehicle speed based on the target vehicle speed;
In a vehicle follow-up travel control device comprising:
Filter means (M5) for filtering the target vehicle speed of the host vehicle output by the target vehicle speed calculation means (M3);
A rear-end collision prediction time calculation means (M6 ′) for calculating a rear-end collision prediction time with the preceding vehicle based on the inter-vehicle distance from the preceding vehicle;
Filter characteristic changing means (M7) for changing the characteristics of the filter means (M5) according to the predicted collision time with the preceding vehicle;
Equipped with a,
The filter means (M5) is composed of a plurality of low-pass filters having a cutoff frequency between 0.08 Hz and 2 Hz,
The vehicle follow-up travel control device, wherein the filter characteristic changing means (M7) switches to a low-pass filter having a higher cut-off frequency when a rear-end collision prediction time with a preceding vehicle becomes a predetermined value or less .