JP3770301B2 - Vehicle behavior control device - Google Patents

Description

【００２３】
式１の左辺と右辺との比較によりグリップ状態の判別を行う場合には、路面のカント等の準定常的な横加速度のノイズによる影響を受けないが、リアルタイムの判定が行われるため悪路走行時等に於ける路面よりの外乱入力の如き過渡的なノイズの影響は免れない。またこの判定は横加速度やヨーレート等の一般にアナログ式に検出されるセンサ出力に直接依存しており、これらのセンサ系は浮動的に故障する場合があり、そのため実際には車輌がグリップ状態にあるにも拘らず非グリップ状態であると判別される虞れがある。
【００２４】
上記式１を移項して展開すると、操舵角θf、後輪の実舵角δr、ヨーレートγを前後速度Ｖxにて除算した値は前輪のスリップ角αfと後輪のスリップ角αrとの差に他ならず、発生している横加速度Ｇyに比例する。即ち下記の式２が成立する。

【００２５】
上記式２の関係を大まかに把握すると、路面の摩擦係数が高く横加速度Ｇyも大きく発生すればそれに応じてスリップ角の偏差αf−αrが大きくなり得ることが解る。従ってＧy−Ｖ＊γに基づく判定系とは別に、操舵角θf、後輪の実舵角δr、ヨーレートγより前後輪のスリップ角の偏差αf−αrをリアルタイムに算出すると共に、横加速度Ｇyに基づき路面の摩擦係数μgを推定し、下記の式３にて表される前後輪のスリップ角の偏差の大きさに基づくグリップ判定の基準値を路面の摩擦係数μgに応じて増減する判定系を構成することができ、この判定系によれば仮に横加速度Ｇyに過渡的なノイズが重畳したとしても横加速度が路面の摩擦係数として把握されることにより誤判定要因を吸収することができる。
｜θf／Ｎ−δr−（γ／Ｖx）＊Ｌ｜＝｜αf−αr｜ ……（３）
【００２６】
更に上記式３の値に基づく判定系に於けるヨーレートγの代替値として下記の式４にて表されている如く横加速度Ｇyを前後速度Ｖxにて除算した値を用いることが可能である。
｜θf／Ｎ−δr−（Ｇy／Ｖx²）＊Ｌ｜＝｜αf−αr｜ ……（４）
【００２７】
路面にカントがついていない状況に於ける準静的なグリップ状態に於いては、この横加速度Ｇyによる代替値はヨーレートγと同等の値になる。この特性を利用し、前輪の操舵角θf、後輪の実舵角δr、ヨーレートγに基づく第一の判定系と、操舵角θf、後輪の実舵角δr、横加速度Ｇyに基づく第二の判定系との二重の判定系を構築し、これらの判定系の両方の値が摩擦係数μgに応じて増減される基準値を越えない限り車輌がグリップ状態にあると判別することにより、横加速度Ｇy及びヨーレートγに基づく判定系に対する冗長判定系を組むことが可能になる。
【００２８】
【発明の実施の形態】
以下に添付の図を参照しつつ、本発明を好ましい実施形態について詳細に説明する。
【００２９】
図１は後輪駆動車に適用された本発明による挙動制御装置の一つの実施形態を示す概略構成図（Ａ）及び制御系のブロック線図（Ｂ）である。
【００３０】
図１に於いて、１０はエンジンを示しており、エンジン１０の駆動力はトルクコンバータ１２及びトランスミッション１４を含む自動変速機１６を介してプロペラシャフト１８へ伝達される。プロペラシャフト１８の駆動力はディファレンシャル２０により左後輪車軸２２L及び右後輪車軸２２Rへ伝達され、これにより駆動輪である左右の後輪２４RL及び２４RRが回転駆動される。
【００３１】
一方左右の前輪２４FL及び２４FRは従動輪であると共に操舵輪であり、図１には示されていないが、運転者によるステアリングホイールの転舵に応答して駆動されるラック・アンド・ピニオン式のパワーステアリング装置によりタイロッドを介して操舵される。
【００３２】
左右の前輪２４FL、２４FR及び左右の後輪２４RL、２４RRの制動力は制動装置２６の油圧回路２８により対応するホイールシリンダ３０FL、３０FR、３０RL、３０RRの制動圧が制御されることによって制御される。図１には示されていないが、油圧回路２８はオイルリザーバ、オイルポンプ、種々の弁装置等を含み、各ホイールシリンダの制動圧は通常時には運転者によるブレーキペダル３２の踏み込み操作に応じて駆動されるマスタシリンダ３４により制御され、また必要に応じて後に詳細に説明する如く挙動制御用電子制御装置３６により制御される。
【００３３】
挙動制御用電子制御装置３６には前後加速度センサ３８より車輌の前後加速度Ｇxを示す信号、横加速度センサ４０より車輌の横加速度Ｇyを示す信号、ヨーレートセンサ４２より車輌のヨーレートγを示す信号、操舵角センサ４４より前輪の操舵角θfを示す信号、操舵角センサ４６より後輪の実舵角δrを示す信号、車輪速度センサ４８i（ｉ＝fl、fr、rl、rr）より左右前輪及び左右後輪の車輪速度（周速）Ｖwiを示す信号が入力される。
【００３４】
また駆動輪である後輪２４RL若しくは２４RRの加速スリップが過大であるときにはその加速スリップを低減すべく、左右の後輪のホイールシリンダ３０RL、３０RRの制動圧はトラクション制御用電子制御装置５０により後に詳細に説明する如く制御される。トラクション制御用電子制御装置５０には挙動制御用電子制御装置３６より各車輪の車輪速度Ｖwiを示す信号が入力され、電子制御装置５０は左後輪若しくは右後輪についてトラクション制御を行うときにはそのことを示す信号を電子制御装置３６へ出力する。
【００３５】
尚挙動制御用電子制御装置３６及びトラクション制御用電子制御装置５０は実際にはＣＰＵ、ＲＯＭ、ＲＡＭ、入出力ポート装置を含む周知の構成のマイクロコンピュータと駆動回路とよりなるものであってよい。また前後加速度センサ３８は車輌の加速方向を正として前後加速度を検出し、横加速度センサ４０、ヨーレートセンサ４２、操舵角センサ４４及び４６は車輌の左旋回方向を正として横加速度等を検出するようになっている。
【００３６】
また挙動制御用電子制御装置３６は、後述の如く図２〜図６の制御フロー及び図８〜図１１のマップを記憶しており、上述の種々のセンサにより検出されたパラメータに基づき後述の如く種々の演算を行い、車輌の旋回挙動を判定するためのスピン状態量ＳＳを求めると共に、グリップ状態指標値Ｇγ及びＧgyを求め、スピン状態量及びグリップ状態指標値に基づき車輌の横滑り状態を判定し、その判定結果に基づき各輪の制動力を制御して旋回挙動を制御すると共に、必要に応じて警報装置５２を作動するようになっている。
【００３７】
一方トラクション制御用電子制御装置５０は、従動輪である左右前輪２４FL及び２４FRの車輪速度Ｖwfl及びＶwfrに基づき制御の基準となる車体速度Ｖbを演算し、車体速度Ｖbに基づき左右後輪の加速スリップＳdrl及びＳdrrを演算し、加速スリップが基準値以上であるときには加速スリップに応じた制動力を対応する車輪に与えて加速スリップを低減するトラクション制御を行う。
【００３８】
次に図２に示されたフローチャートを参照して車輌の挙動制御ルーチンについて説明する。尚図２に示されたフローチャートによる制御は図には示されていないイグニッションスイッチの閉成により開始され、所定の時間毎に繰返し実行される。また図２に示されたフローチャートに於いて、フラグＦは車輌が非グリップ状態であるか否かに関するものであり、１は車輌が非グリップ状態であることを示している。
【００３９】
まずステップ１０に於いては前後加速度センサ３８より車輌の前後加速度Ｇxを示す信号等の読込みが行われ、ステップ２０に於いては車輪速度Ｖwiに基づき当技術分野に於いて公知の要領にて車速（車体速度）が演算されると共に、横加速度Ｇyと車速Ｖ及びヨーレートγの積Ｖ＊γとの偏差Ｇy−Ｖ＊γとして横加速度の偏差、即ち車輌の横すべり加速度Ｖydが演算され、ステップ３０に於いては横すべり加速度Ｖydが積分されることにより車体の横すべり速度Ｖyが演算され、車体の前後速度Ｖx（＝車速Ｖ）に対する車体の横すべり速度Ｖyの比Ｖy／Ｖxとして車体のスリップ角βが演算される。
【００４０】
ステップ４０に於いてはＫ1及びＫ2をそれぞれ正の定数として車体のスリップ角β及び横すべり加速度Ｖydの線形和Ｋ1＊β＋Ｋ2＊Ｖydとしてスピン量ＳＶが演算され、ステップ５０に於いてはヨーレートγの符号に基づき車輌の旋回方向が判定され、スピン状態量ＳＳが車輌が左旋回のときにはＳＶとして、車輌が右旋回のときには−ＳＶとして演算され、演算結果が負の値のときにはスピン状態量は０とされる。尚スピン量ＳＶは車体のスリップ角β及びその微分値βdの線形和として演算されてもよい。
【００４１】
ステップ６０に於いてはフラグＦが１であるか否かの判別、即ち車輌が非グリップ状態であるか否かの判別が行われ、肯定判別が行われたときにはステップ８０に於いてスピン状態量ＳＳに基づき図１０に示されたグラフに対応するマップより車輌全体の目標スリップ率であるスピン制御量Ｒsspinが演算され、否定判別が行われたときにはステップ７０へ進む。
【００４２】
ステップ７０に於いては左右の後輪２４RL及び２４RRの両者がトラクション制御中であるか否かの判別が行われ、肯定判別が行われたときにはステップ８０へ進み、否定判別が行われたときにはステップ９０に於いてスピン制御量Ｒsspinが０にセットされる。
【００４３】
ステップ１００に於いてはスピン制御量Ｒsspinが０であるか否かの判別、即ち車輌の挙動が安定であり挙動制御が不要であるか否かの判別が行われ、肯定判別が行われたときにはステップ１１０に於いて油圧回路２８の各弁装置が非制御位置に制御された後ステップ１０へ戻り、否定判別が行われたときにはステップ１２０に於いて下記の式５に従って旋回外側前輪、旋回内側前輪、旋回外側後輪、旋回内側後輪の目標スリップ率Ｒsfo、Ｒsfi、Ｒsro、Ｒsriが演算される。
Ｒsfo＝Ｒsspin
Ｒsfi＝０
Ｒsro＝−Ｒsspin／２
Ｒsri＝−Ｒsspin／２ ……（５）
【００４４】
ステップ１３０に於いてはヨーレートγの符号に基づき車輌の旋回方向が判定されることにより旋回内外輪が特定され、その特定結果に基づき各輪の最終目標スリップ率Ｒsi（ｉ＝fr、fl、rr、rl）が演算される。即ち最終目標スリップ率Ｒsiが車輌の左旋回の場合及び右旋回の場合についてそれぞれ下記の式６及び式７に従って求められる。
Ｒsfr＝Ｒsfo
Ｒsfl＝Ｒsfi
Ｒsrr＝Ｒsro
Ｒsrl＝Ｒsri ……（６）
Ｒsfr＝Ｒsfi
Ｒsfl＝Ｒsfo
Ｒsrr＝Ｒsri
Ｒsrl＝Ｒsro ……（７）
【００４５】
ステップ１４０に於いては各車輪のスリップ率が最終目標スリップ率Ｒsiになるよう例えば車輪速度フィードバック制御により各車輪の制動力が制御され、これにより車輌のスピン状態が抑制され車輌の挙動が安定化され、しかる後ステップ１０へ戻る。尚この場合、最終目標スリップ率が正の値であるときには対応する車輪のホイールシリンダの圧力が増圧され、最終目標スリップ率が負の値であるときには対応する車輪のホイールシリンダの圧力が減圧される。
【００４６】
次に図３に示されたフローチャートを参照して路面の摩擦係数の推定値μg の演算ルーチンについて説明する。尚図３に示されたフローチャートによる制御は所定時間毎の割り込みにより実行される。
【００４７】
まずステップ２１０に於いては横加速度センサ７８により検出された車輌の横加速度Ｇyを示す信号等の読込みが行われ、ステップ２２０に於いては路面の摩擦係数の推定値μgを演算するための車輌の水平加速度Ｇxyが下記の式８に従って演算される。
Ｇxy＝（Ｇx²＋Ｇy²）^1/2 ……（８）
【００４８】
ステップ２３０に於いては水平加速度Ｇxyが１サイクル前の水平加速度Ｇxy(n-1)を越えているか否かの判別が行われ、肯定判別が行われたときにはステップ２４０に於いて係数Ｋが１に設定され、否定判別が行われたときにはステップ２５０に於いて係数Ｋが０．０１に設定される。ステップ２６０に於いては路面の摩擦係数の推定値μgが下記の式９に従って演算される。
μg＝（１−Ｋ）＊μg(n-1)＋Ｋ＊Ｇxy ……（９）
【００４９】
尚図示の実施形態に於いては、路面の摩擦係数はＧx及びＧyの二乗和平方根として演算されるようになっているが、車輌の横加速度Ｇyの絶対値により推定されてもよく、また車輌のヨーイングにより発生する前輪位置及び後輪位置に於ける横加速度成分Ｇyfy、Ｇyryが演算され、これらの成分及び車輌の横加速度Ｇyの和として前輪位置及び後輪位置に於ける横加速度成分Ｇyf、Ｇyrが演算され、Ｇyf及びＧyrの大きい方の値が横加速度Ｇysとして演算され、Ｇx及びＧysの二乗和平方根として演算されてもよい。
【００５０】
次に図４及び図５に示されたフローチャートを参照してフラグＦ設定ルーチン、即ち車輌のグリップ状態判定ルーチンについて説明する。尚図４及び図５に示されたフローチャートによる制御も所定時間毎の割り込みにより実行される。
【００５１】
このルーチンのステップ３１０に於いては操舵角θfを示す信号等の読込みが行われ、ステップ３２０及び３３０に於いては車輌の前後速度Ｖx（＝Ｖ）に基づきそれぞれ図９及び図１０に示されたグラフに対応するマップより低速処理用係数Ｋa及びＫbが演算される。
【００５２】
ステップ３４０に於いては下記の式１０に従って前輪のスリップ角と後輪のスリップ角との偏差に対応する第一のパラメータ、即ちヨーレートγに基づく操舵角偏差ΔＳγが演算される。
ΔＳγ＝｛θf−δr＊Ｎ−（Ｎ＊Ｌ／Ｖx）＊γ｝＊Ｋa ……（１０）
【００５３】
ステップ３５０に於いては下記の式１１に従って前輪のスリップ角と後輪のスリップ角との偏差に対応する第二のパラメータ、即ち横加速度Ｇyに基づく操舵角偏差ΔＳgyが演算される。
ΔＳgy＝｛θf−δr＊Ｎ−（Ｎ＊Ｌ／Ｖx²）＊Ｇy｝＊Ｋb ……（１１）
【００５４】
ステップ３６０に於いては図３に示されたフローチャートに従って演算された路面の摩擦係数μgに基づき図１１に示されたグラフに対応するマップより不感帯設定値μgmが演算され、ステップ３７０に於いてはＫcを正の定数として下記の式１２に従って第一のパラメータに基づくグリップ状態指標値Ｇγが演算される。
Ｇγ＝（｜ΔＳγ｜−μgm）＊Ｋc ……（１２）
【００５５】
ステップ３８０に於いてはグリップ状態指標値Ｇγが負であるか否かの判別が行われ、否定判別が行われたときにはそのままステップ４００へ進み、肯定判別が行われたときにはステップ３９０に於いてグリップ状態指標値Ｇγが０にセットされる。
【００５６】
ステップ４００に於いてはＫdを正の定数として下記の式１３に従って第二のパラメータに基づくグリップ状態指標値Ｇgyが演算され、ステップ４００に於いては指標値Ｇgyが負であるか否かの判別が行われ、否定判別が行われたときにはそのままステップ４３０へ進み、肯定判別が行われたときにはステップ４２０に於いて指標値Ｇgyが０にセットされる。尚不感帯設定値μgmは路面の摩擦係数μgが高いほど大きい値になるので、グリップ状態指標値Ｇγ及びＧgyは路面の摩擦係数が高いほど小さい値になる。
Ｇgy＝（｜ΔＳgy｜−μgm）＊Ｋd ……（１３）
【００５７】
ステップ４３０に於いてはグリップ状態指標値Ｇγが基準値Ｇγ1（正の定数）を越えているか否かの判別、即ち第一のパラメータに基づく判定が非グリップ状態であるか否かの判別が行われ、肯定判別が行われたときにはステップ４４０に於いてフラグＦ1が１にセットされ、否定判別が行われたときにはステップ４５０に於いてフラグＦ1が０にリセットされる。
【００５８】
ステップ４６０に於いてはグリップ状態指標値Ｇgyが基準値Ｇgy1（正の定数）を越えているか否かの判別、即ち第二のパラメータに基づく判定が非グリップ状態であるか否かの判別が行われ、肯定判別が行われたときにはステップ４７０に於いてフラグＦ2が１にセットされ、否定判別が行われたときにはステップ４８０に於いてフラグＦ2が０にリセットされる。
【００５９】
ステップ４９０に於いてはフラグＦ1が１であり且つフラグＦ2が１であるか否かの判別、即ち第一のパラメータに基づく判定及び第二のパラメータに基づく両方の判定が非グリップ状態であるか否かの判別が行われ、否定判別が行われたときにはステップ５３０へ進み、肯定判別が行われたときにはステップ５００に於いてカウンタのカウント値Ｃ1が１インクリメントされる。
【００６０】
ステップ５１０に於いてはカウント値Ｃ1が基準値ｔ1（正の定数）を越えているか否かの判別、即ち第一のパラメータに基づく判定及び第二のパラメータに基づく判定の両者により非グリップ状態である旨の判定が行われる状態が所定時間以上継続したか否かの判別が行われ、否定判別が行われたときにはそのままこのルーチンを終了し、肯定判別が行われたときにはステップ５２０に於いてフラグＦが１にセットされる。
【００６１】
ステップ５３０に於いてはカウント値Ｃ1が０にリセットされ、ステップ５４０に於いてはフラグＦが１であるか否かの判別が行われ、否定判別が行われたときにはそのままステップ５７０へ進み、肯定判別が行われたときにはステップ５５０へ進む。
【００６２】
ステップ５５０に於いてはフラグＦ1が０であるか否かの判別が行われ、肯定判別が行われたときにはステップ５６０に於いてカウンタのカウント値Ｃ2が１インクリメントされ、否定判別が行われたときにはステップ５７０に於いてカウント値Ｃ2が０にリセットされる。
【００６３】
ステップ５８０に於いてはカウント値Ｃ2が基準値ｔ2（正の定数）を越えているか否かの判別、即ち第一及び第二のパラメータに基づく判定により非グリップ状態である旨の判別が行われた後第一のパラメータに基づく判定によりグリップ状態である旨の判定が行われる状態が所定時間以上継続したか否かの判別が行われ、否定判別が行われたときにはそのままこのルーチンを終了し、肯定判別が行われたときにはステップ５９０に於いてフラグＦが０にリセットされる。
【００６４】
図示の実施形態のグリップ状態判別ルーチンによれば、ステップ３２０及び３４０に於いて操舵角θf及びヨーレートγに基づき前輪のスリップ角と後輪のスリップ角との偏差に対応する第一のパラメータとして操舵角偏差ΔＳγが演算され、ステップ３６０〜３９０に於いて操舵角偏差ΔＳγ及び路面の摩擦係数μgに基づくグリップ状態指標値Ｇγが演算され、ステップ４３０〜４５０に於いてグリップ状態指標値Ｇγに基づき非グリップ状態であるか否かの判別が行われ、非グリップ状態であるときにはフラグＦ1が１にセットされる。
【００６５】
同様にステップ３３０及び３５０に於いて操舵角θf及び横加速度Ｇyに基づき前輪のスリップ角と後輪のスリップ角との偏差に対応する第二のパラメータとして操舵角偏差ΔＳgyが演算され、ステップ３６０及びステップ４００〜４２０に於いて操舵角偏差ΔＳgy及び路面の摩擦係数μgに基づくグリップ状態指標値Ｇgyが演算され、ステップ４６０〜４８０に於いてグリップ指標値Ｇgyに基づき非グリップ状態であるか否かの判別が行われ、非グリップ状態であるときにはフラグＦ2 が１にセットされる。
【００６６】
そしてステップ４９０に於いてグリップ状態指標値Ｇγに基づく判定及びグリップ状態指標値Ｇgyに基づく判定の何れも非グリップ状態であるか否かの判別が行われ、これら二つの非グリップ状態の判別が所定時間以上継続するとステップ５１０に於いて肯定判別が行われ、フラグＦが１にセットされる。換言すれば操舵角及びヨーレートに基づく操舵角偏差ΔＳγ、操舵角及び横加速度に基づく操舵角偏差ΔＳgyの両方が路面の摩擦係数に見合った偏差よりも大きい状態が所定時間以上継続した場合に非グリップ状態であると判定される。
【００６７】
また一旦フラグＦが１にセットされた後フラグＦ1又はＦ2が０になると、即ちグリップ状態指標値Ｇγに基づく判定又はグリップ状態指標値Ｇgyに基づく判定の何れかがグリップ状態になると、ステップ４９０に於いて否定判別が行われると共にステップ５４０に於いて肯定判別が行われ、ステップ５５０に於いてフラグＦ1 が０であるか否かの判別が行われ、フラグＦ1 が０である状態が所定時間以上継続するとステップ５９０に於いてフラグＦが０にリセットされる。
【００６８】
従って第一及び第二のパラメータに基づく両方の判定により一旦非グリップ状態である旨の判別が行われると、操舵角及びヨーレートに基づく操舵角偏差ΔＳγが路面の摩擦係数に見合った偏差よりも小さい状態が所定時間以上継続した場合にグリップ状態と判定される。
【００６９】
次に図６に示されたフローチャートを参照して警報処理ルーチンについて説明する。尚図６に示されたフローチャートによる制御も所定時間毎の割り込みにより実行される。
【００７０】
このルーチンのステップ７１０に於いてはフラグＦが１であるか否かの判別、即ち車輌が非グリップ状態であるか否かの判別が行われ、否定判別が行われたときにはそのままこのルーチンを終了し、肯定判別が行われたときにはステップ７２０へ進む。
【００７１】
ステップ７２０に於いては車速Ｖが基準値Ｖoを越えているか否かの判別、即ち車輌が所定車速以上の走行状態にあるか否かの判別が行われ、否定判別が行われたときにはそのままこのルーチンを終了し、肯定判別が行われたときにはステップ７３０に於いて警報装置９０が作動され、運転者に車輌が非グリップ状態である旨の警報が発せられる。
【００７２】
次に図７に示されたフローチャートを参照して図示の実施形態に於けるトラクション制御について説明する。尚図７に示されたフローチャートによる制御も所定時間毎の割り込みにより実行される。
【００７３】
まずステップ８１０に於いては挙動制御用電子制御装置３６より各車輪の車輪速度Ｖwiを示す信号が入力され、ステップ８２０に於いては従動輪である左右前輪２４FL及び２４FRの車輪速度Ｖwfl及びＶwfrに基づき当技術分野に於いて公知の要領にてトラクション制御の基準となる車体速度Ｖbが演算される。
【００７４】
ステップ８３０に於いては車体速度Ｖbに基づき下記の式１４及び１５に従って左右後輪の加速スリップＳdrl及びＤdrrが演算される。
Ｓdrl＝Ｖwrl−Ｖb ……（１４）
Ｓdrr＝Ｖwrr−Ｖb ……（１５）
【００７５】
ステップ８４０に於いては左後輪の加速スリップＳdrlが基準値Ｓdo（正の定数）以上であるか否かの判別が行われ、否定判別が行われたときにはそのままステップ８６０へ進み、肯定判別が行われたときにはステップ８５０に於いて左後輪が加速スリップＳdrlに応じた制動力にて制御されることにより左後輪について加速スリップを低減するトラクション制御が行われる。
【００７６】
ステップ８６０に於いては右後輪の加速スリップＳdrrが基準値Ｓdo以上であるか否かの判別が行われ、否定判別が行われたときにはそのままステップ８１０へ戻り、肯定判別が行われたときにはステップ８７０に於いて右後輪が加速スリップＳdrrに応じた制動力にて制御されることにより右後輪について加速スリップを低減するトラクション制御が行われる。
【００７７】
尚車輌の横滑り状態抑制制御としてのスピン抑制制御、車輌のグリップ状態の判定自体及びトラクション制御自体は本発明の要旨をなすものではなく、これらの制御及び判定は当技術分野に於いて公知の任意の要領にて行われてよい。例えば図示の実施形態のトラクション制御に於いては、駆動輪の加速スリップＳdrr、Ｓdrlが基準値Ｓdo以上であるときには当該駆動輪が加速スリップに応じた制動力にて制御されるようになっているが、加速スリップが第一の基準値Ｓdo1以上になると当該駆動輪が加速スリップに応じた制動力にて制御されるトラクション制御が開始され、加速スリップが第一の基準値Ｓdo1よりも小さい第二の基準値Ｓso2未満になるとトラクション制御が終了するよう修正されてもよい。
【００７８】
かくして図示の実施形態に於いては、ステップ２０に於いて車体の横すべり加速度Ｖydが演算され、ステップ３０に於いて車体のスリップ角βが演算され、ステップ４０に於いてこれらの線形和としてスピン量ＳＶが演算され、ステップ５０に於いてスピン量ＳＶが絶対値化された値としてスピン状態量ＳＳが演算される。
【００７９】
そしてステップ６０に於いて車輌が非グリップ状態であるか否かの判別が行われ、車輌が非グリップ状態にある旨の判別が行われたときにはステップ８０に於いてスピン状態量ＳＳに基づき図１０に示されたグラフに対応するマップよりスピン制御量Ｒsspinが演算され、車輌がグリップ状態にある旨の判別が行われたときにはステップ７０に於いて左右の後輪がトラクション制御中であるか否かの判別が行われる。
【００８０】
そしてステップ７０に於いて左右後輪の少なくとも一方がトラクション制御中ではない旨の判別が行われたときにはステップ９０に於いてスピン制御量Ｒsspinが０にセットされるが、左右の後輪がトラクション制御中である旨の判別が行われたときにはステップ８０に於いてスピン状態量ＳＳに基づき図１０に示されたグラフに対応するマップよりスピン制御量Ｒsspinが演算される。更にステップ１００に於いてスピン制御量Ｒsspinに基づき車輌の旋回挙動が安定であるか否かの判別が行われる。
【００８１】
車輌の旋回挙動が安定な状態にあるときには、ステップ１００に於いて肯定判別が行われることによりステップ１１０に於いて油圧回路２８の各弁装置が非制御位置に制御された後ステップ１０へ戻り、従ってこの場合にはステップ１２０〜１４０による挙動制御は実行されず、これにより各車輪の制動力は運転者によるブレーキペダル３２の踏込み量に応じて制御される。
【００８２】
また車輌の旋回挙動がスピン状態にあるときには、ステップ１００に於いて否定判別が行われ、ステップ１２０及び１３０に於いて各車輪の最終目標スリップ率Ｒsiが演算され、ステップ１４０に於いて各車輪の目標スリップ率が最終目標スリップ率Ｒsiになるよう各車輪の制動力が制御される。
【００８３】
従って図示の実施形態によれば、車輌がスピン状態にあると判定され車輌が非グリップ状態にあると判定されたときには、スピン抑制制御を実行して車輌のスピン状態を低減し車輌の挙動を安定化させることができ、車輌がスピン状態にあると判定され車輌がグリップ状態にあると判定され左右後輪の少なくとも一方がトラクション制御中ではない旨の判別が行われたときには、不必要なスピン抑制制御が実行されることを防止することができ、更に車輌がスピン状態にあると判定され車輌がグリップ状態にあると判定された場合であっても左右の後輪がトラクション制御中である旨の判別が行われたときには、必要なスピン抑制制御を実行して車輌のスピン状態を低減し車輌の挙動を安定化させることができる。
【００８４】
また一般に、左右後輪の一方がトラクション制御されている状況に於いても当該車輪とは左右反対の車輪により或る程度の横力が確保されており、また左右後輪の一方が瞬間的にトラクション制御される状況に於いてはトラクション制御により当該車輪の横力もすぐに回復するので、車輌がスピン状態にあると判定され車輌がグリップ状態にあると判定された場合であっても左右後輪の一方しかトラクション制御されていない状況に於いては、スピン抑制制御が実行されないことが好ましい。
【００８５】
図示の実施形態によれば、車輌がスピン状態にあると判定され車輌がグリップ状態にあると判定された場合であっても左右後輪の一方しかトラクション制御されていない状況に於いては、ステップ７０に於いて否定判別が行われることによりステップ９０に於いてスピン制御量Ｒsspinが０にセットされるので、かかる状況に於いて不必要なスピン抑制制御が実行されることを確実に防止することができる。
【００８６】
以上に於ては本発明を特定の実施形態について詳細に説明したが、本発明は上述の実施形態に限定されるものではなく、本発明の範囲内にて他の種々の実施形態が可能であることは当業者にとって明らかであろう。
【００８７】
例えば上述の実施形態に於いては、車輌は後輪駆動車であるが、本発明が適用される車輌は例えば四輪駆動車であってもよい。
【００８８】
また上述の実施形態に於いては、スピン制御のための目標スリップ率は上記式５に従って演算され、左右後輪の制動力が低減されるようになつているが、スピン抑制制御は左右後輪の制動力を変化させることなく旋回外側前輪に制動力を付与することより達成されてもよい。
【００８９】
また上述の実施形態に於いては、第一のパラメータとしての操舵角偏差ΔＳγ及び第二のパラメータとしての操舵角偏差ΔＳgyの両方に基づき非グリップ状態であるか否かの判別が行われるようになっているが、必要ならば第二のパラメータに基づく非グリップ状態の判別は省略されてもよい。その場合にはステップ３３０、３５０、４００〜４２０、４６０〜４８０が省略され、ステップ４９０に於いてはフラグＦ1 が１であるか否かの判別が行われ、ステップ５４０〜５８０は省略される。
【００９０】
また上述の実施形態に於いては、警報処理ルーチンに於いて車速Ｖが基準値Ｖo を越えている否かの判別が行われるようになっているが、必要ならばこの判別ステップは省略されてもよい。但し氷雪路面の如く路面の摩擦係数が非常に低い場合に於ける車輌の発進時には非グリップ状態になり易く、車速判別が省略されると警報装置が作動される頻度が高くなり運転者が煩わしく感じる場合もあるので、かかる問題を解消すべく図示の各実施形態の如く車速判別が行われることが好ましい。
【００９１】
【発明の効果】
以上の説明より明らかである如く、本発明の請求項１の構成によれば、車輌の横滑り状態が推定された場合であっても車輌がグリップ状態にあるときには、横滑り抑制手段による横滑り状態抑制制御が禁止されるので、横滑り状態抑制制御が不必要に実行されることを防止することができ、車輌がグリップ状態にあると判別された場合であって左右の駆動輪の両方について加速スリップ制御手段による加速スリップ抑制制御が実行されており駆動輪の横力が低下しているときには横滑り抑制手段による横滑り状態抑制制御が許可されるので、駆動輪の横力が低下し車輌が横滑りし易い状況に於いて横滑り抑制手段による横滑り状態抑制制御を実行して車輌の横滑り状態を確実に抑制することができ、車輌がグリップ状態にあると判別された場合に於いて左右の駆動輪の少なくとも一方について加速スリップ制御手段による加速スリップ抑制制御が実行されていないときには横滑り抑制手段による横滑り状態抑制制御が禁止されるので、左右の駆動輪の両方の横力が低下している場合に比して車輌の横滑りの虞れが低い状況に於いて不必要な横滑り状態抑制制御が実行されることを防止することができる。
【００９３】
また請求項２の構成によれば、駆動輪は左右の後輪であるので、加速スリップ抑制制御によって左右の後輪に制動力が付与されることによりそれらの横力が低下することに起因する車輌のスピン状態を確実に抑制することができる。
【００９４】
また請求項３の構成によれば、車輪の制動力を個別に制御することにより車輌の横滑りが抑制されるので、加速スリップ抑制制御によって制動力が付与されている車輪以外の車輪に制動力を付与し車輌に横滑りを抑制するモーメントを付与して車輌の横滑り状態を確実に抑制することができる。
【図面の簡単な説明】
【図１】後輪駆動車に適用された本発明による挙動制御装置の一つの実施形態を示す概略構成図（Ａ）及び制御系のブロック線図（Ｂ）である。
【図２】実施形態に於ける挙動制御ルーチンを示すフローチャートである。
【図３】実施形態に於ける路面の摩擦係数の推定値μg の演算ルーチンを示すフローチャートである。
【図４】実施形態に於ける車輌のグリップ状態判定ルーチンの前半を示すフローチャートである。
【図５】実施形態に於ける車輌のグリップ状態判定ルーチンの後半を示すフローチャートである。
【図６】実施形態に於ける警報処理ルーチンを示すフローチャートである。
【図７】実施形態に於けるトラクション制御ルーチンを示すフローチャートである。
【図８】スピン状態量ＳＳとスピン制御量Ｒsspin との間の関係を示すグラフである。
【図９】前後速度Ｖx と低速処理用係数Ｋa との間の関係を示すグラフである。
【図１０】前後速度Ｖx と低速処理用係数Ｋb との間の関係を示すグラフである。
【図１１】路面の摩擦係数μg と不感帯設定値μgmとの間の関係を示すグラフである。
【符号の説明】
１０…エンジン
１６…自動変速機
２８…油圧回路
３０FL、３０FR、３０RL、３０RR…ホイールシリンダ
３４…マスタシリンダ
３６…挙動制御用電子制御装置
３８…前後加速度センサ
４０…横加速度センサ
４２…ヨーレートセンサ
４４、４６…操舵角センサ
４８FL〜４８RR…車輪速センサ
５０…トラクション制御用電子制御装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a behavior control device for a vehicle such as an automobile, and more particularly to a behavior control device for suppressing and reducing a side slip of a vehicle such as a spin during a turn.
[0002]
[Prior art]
As one of behavior control devices for suppressing and reducing the side slip of a vehicle such as an automobile, for example, as described in Japanese Patent Application Laid-Open No. 9-123888 filed by the applicant of the present application, the side slip state of the vehicle is estimated and the side slip is estimated. A vehicle behavior control device having behavior control means for executing side slip condition suppression control when a state is estimated, wherein the vehicle has a grip state judgment means for judging whether or not the vehicle is in a grip state with respect to a road surface, 2. Description of the Related Art Conventionally, a vehicle behavior control device having means for prohibiting skid state suppression control by behavior control means when it is determined that the vehicle is in a grip state is known.
[0003]
According to such a behavior control device, when it is determined that the vehicle is in the grip state, the side slip state suppression control by the behavior control means is prohibited, so the side slip state suppression control is not executed even if the side slip state of the vehicle is estimated. Therefore, unnecessary braking force control is performed due to the inaccurate estimation of the side slip state of the vehicle, and the possibility that the behavior of the vehicle is impaired instead can be reduced.
[0004]
[Problems to be solved by the invention]
However, it may be preferable to execute the skid state suppression control even in a situation where it is determined that the vehicle is in the grip state. For example, even when the vehicle is a rear wheel drive vehicle and the grip state determination means determines that the vehicle is in a grip state, the rear wheel is in an excessively accelerated slip state and braking force is applied. In a situation where acceleration slip suppression control (traction control) is being performed by the vehicle, the lateral force of the rear wheel is reduced and the rear wheel side of the vehicle tends to slip sideways, so it is necessary to allow side slip state suppression control to be permitted There is.
[0005]
However, in the above-described conventional behavior control apparatus, the side slip state suppression control by the behavior control means is uniformly prohibited when it is determined that the vehicle is in the grip state. There is a problem in that it is impossible to suppress the side slip and stabilize the behavior of the vehicle.
[0006]
The present invention has been made in view of the above-described problems in the conventional behavior control device configured to prohibit the side slip state suppression control by the behavior control means when it is determined that the vehicle is in the grip state. The main problem of the present invention is to make it possible to perform the skid state suppression control as necessary in a situation where the acceleration slip suppression control by applying a braking force to the drive wheel is performed. Thus, even in a situation where the acceleration slip suppression control by applying a braking force to the driving wheel is being executed, the side slip of the vehicle is reliably suppressed.
[0007]
[Means for Solving the Problems]
According to the present invention, the main problem described above is the configuration of claim 1, that is, means for estimating the side slip state of the vehicle, and side slip suppression means for executing the side slip state suppression control when the side slip state of the vehicle is estimated. In the vehicle behavior control device, comprising: a grip state determination unit that determines whether or not the vehicle is in a grip state with respect to a road surface; and a determination unit that determines whether or not the side slip state suppression control by the side slip suppression unit is possible. The vehicle has acceleration slip control means for executing acceleration slip suppression control by applying a braking force to the driving wheel when the acceleration slip of the driving wheel is excessive. When it is determined that the vehicle is in the grip state, the side slip state suppression control by the side slip suppression unit is permitted, and the vehicle is gripped by the grip state determination unit. It is determined to be in the state Sometimes By the acceleration slip control means R Accelerated slip suppression system Love Is The wheels are both left and right drive wheels sometimes only In the case where the side slip state suppression control by the side slip suppression unit is permitted, and the grip state determination unit determines that the vehicle is in the grip state. About at least one of the left and right drive wheels This is achieved by a vehicle behavior control device for prohibiting the side slip state suppression control by the side slip suppression means when the acceleration slip suppression control by the acceleration slip control means is not executed.
[0008]
According to the first aspect of the present invention, when it is determined that the vehicle is in the non-grip state, the side-slip state suppression control by the side-slip suppression unit is permitted, so that the behavior of the vehicle is stabilized by executing the side-slip state suppression control. If it is determined that the vehicle is in grip, For both the left and right drive wheels When the acceleration slip suppression control by the acceleration slip control means is executed and the side force of the driving wheel is reduced, the side slip state suppression control by the side slip suppression means is permitted, so the side force of the drive wheel decreases and the vehicle slips. When the vehicle is judged to be in the grip state, it is possible to execute the side slip state suppression control by the side slip suppression means in a situation where the vehicle is easily gripped. About at least one of the left and right drive wheels When the acceleration slip suppression control by the acceleration slip control means is not executed, the side slip state suppression control by the side slip suppression means is prohibited, In situations where there is a low risk of vehicle skidding compared to when the lateral forces on both the left and right drive wheels are reduced It is possible to prevent unnecessary skid state suppression control from being executed.
[0011]
According to the present invention, in order to effectively achieve the main problems described above, 1 The drive wheels are configured to be left and right rear wheels. 2 Configuration).
[0012]
Claim 2 According to the configuration, since the driving wheels are the left and right rear wheels, the vehicle spin state due to the reduction of the lateral force due to the braking force applied to the left and right rear wheels by the acceleration slip suppression control Is reliably suppressed.
[0013]
According to the present invention, in order to effectively achieve the main problems described above, Or 2 In the above structure, the skid restraining means is configured to restrain the skid of the vehicle by individually controlling the braking force of the wheels. 3 Configuration).
[0014]
Claim 3 With this configuration, since the side slip of the vehicle is suppressed by individually controlling the braking force of the wheel, the braking force is applied to the wheels other than the wheel to which the braking force is applied by the acceleration slip suppression control. It is possible to apply a moment that suppresses side slip.
[0015]
[Preferred embodiment of the problem solving means]
According to one preferred aspect of the present invention, in the configuration of claim 1, the means for estimating the side slip state of the vehicle is configured to estimate the side slip state of the vehicle based on the lateral acceleration and yaw rate of the vehicle. Preferred embodiment 1).
[0016]
According to another preferred aspect of the present invention, in the configuration of claim 1, the grip state determination means includes means for detecting a steering angle, means for determining a friction coefficient of a road surface, and the steering angle and yaw rate. Means for obtaining a first parameter corresponding to a deviation between the slip angle of the front wheel and the slip angle of the rear wheel, and whether the vehicle is gripped with respect to the road surface based on the first parameter and the friction coefficient of the road surface It is configured to determine whether or not (preferred aspect 2).
[0017]
According to another preferred aspect of the present invention, in the configuration of the preferred aspect 2 described above, the grip state determination means further calculates a deviation between the slip angle of the front wheel and the slip angle of the rear wheel based on the steering angle and the lateral acceleration. Means for determining a corresponding second parameter and configured to determine whether or not the vehicle is in a grip state with respect to the road surface based on the first parameter, the second parameter, and the friction coefficient of the road surface ( Preferred embodiment 3).
[0018]
According to another preferable aspect of the present invention, in the configuration of the preferable aspect 3, the grip state determination means determines whether or not the vehicle is in the grip state based on the first parameter and the friction coefficient of the road surface. First discriminating means, and second discriminating means for discriminating whether or not the vehicle is in a grip state based on the second parameter and the friction coefficient of the road surface, the first discriminating means and the second discriminating means When both of the determination means determine that the vehicle is in the non-grip state, the vehicle is determined to be in the non-grip state (Preferable Mode 4).
[0019]
According to another preferred aspect of the present invention, in the configuration of the preferred aspect 4 described above, when the grip state discriminating means once determines that it is in the non-grip state, the first discriminating means determines that the grip state is not in effect. The grip state is determined (Preferred aspect 5).
[0020]
According to another preferred embodiment of the present invention, in the configuration of claim 4, the driving wheels are left and right rear wheels, the side slip state of the vehicle is a side slip state on the rear wheel side of the vehicle, The suppressing means is configured to suppress a side slip of the vehicle by applying a braking force to at least the turning outer front wheel (preferred aspect 6).
[0021]
Principle of the invention
Prior to the description of the embodiment of the present invention, the principle of grip state determination in the present invention will be described.
[0022]
In the situation where the lateral force is generated with the tire in the linear region, even when the cant is attached to the road surface, the following equation is used between the steering angle θf of the front wheels and the lateral acceleration Gy and the yaw rate γ. There is a relationship represented by 1. In Equation 1, δr is the actual steering angle of the rear wheel, N is the steering gear ratio, L is the wheelbase, Kh is the stability factor, Tv is the steering response time constant, Vx is the longitudinal speed of the vehicle, and s is a Laplace operator.

[0023]
When the grip state is discriminated by comparing the left side and the right side of Equation 1, it is not affected by quasi-steady lateral acceleration noise such as cant on the road surface, but it is driven on a rough road because it is judged in real time. The influence of transient noise such as disturbance input from the road surface at times is inevitable. In addition, this determination directly depends on sensor outputs that are generally detected in an analog manner, such as lateral acceleration and yaw rate, and these sensor systems may fail in a floating manner, so that the vehicle is actually in a grip state. Nevertheless, it may be determined that the grip state is not gripped.
[0024]
When the above equation 1 is transferred and expanded, the value obtained by dividing the steering angle θf, the actual steering angle δr of the rear wheel, and the yaw rate γ by the longitudinal speed Vx is the difference between the slip angle αf of the front wheel and the slip angle αr of the rear wheel. Nonetheless, it is proportional to the generated lateral acceleration Gy. That is, the following expression 2 is established.

[0025]
If the relationship of the above equation 2 is roughly grasped, it can be understood that if the road surface friction coefficient is high and the lateral acceleration Gy is large, the slip angle deviation αf−αr can be correspondingly increased. Therefore, apart from the determination system based on Gy−V * γ, the deviation αf−αr of the slip angle of the front and rear wheels is calculated in real time from the steering angle θf, the actual steering angle δr of the rear wheel, and the yaw rate γ, and the lateral acceleration Gy is calculated. A judgment system that estimates the friction coefficient μg of the road surface based on the above and increases or decreases the reference value of the grip judgment based on the magnitude of the deviation of the slip angle of the front and rear wheels expressed by the following formula 3 according to the friction coefficient μg of the road surface. According to this determination system, even if transient noise is superimposed on the lateral acceleration Gy, the erroneous determination factor can be absorbed by grasping the lateral acceleration as a friction coefficient of the road surface.
| Θf / N−δr− (γ / Vx) * L | = | αf−αr | (3)
[0026]
Further, as a substitute value of the yaw rate γ in the determination system based on the value of the above expression 3, a value obtained by dividing the lateral acceleration Gy by the longitudinal speed Vx as represented by the following expression 4 can be used.
| Θf / N-δr- (Gy / Vx ² ) * L | = | αf−αr | (4)
[0027]
In a quasi-static grip state in a situation where the road surface is not canted, the substitute value by the lateral acceleration Gy is equivalent to the yaw rate γ. Using this characteristic, a first determination system based on the steering angle θf of the front wheels, the actual steering angle δr of the rear wheels, and the yaw rate γ, and the second based on the steering angle θf, the actual steering angle δr of the rear wheels, and the lateral acceleration Gy. By constructing a double determination system with the determination system of the above, and determining that the vehicle is in the grip state unless the values of both of these determination systems exceed the reference value that is increased or decreased according to the friction coefficient μg, It becomes possible to build a redundant judgment system for the judgment system based on the lateral acceleration Gy and the yaw rate γ.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0029]
FIG. 1 is a schematic configuration diagram (A) and a control system block diagram (B) showing one embodiment of a behavior control device according to the present invention applied to a rear wheel drive vehicle.
[0030]
In FIG. 1, reference numeral 10 denotes an engine, and the driving force of the engine 10 is transmitted to a propeller shaft 18 via an automatic transmission 16 including a torque converter 12 and a transmission 14. The driving force of the propeller shaft 18 is transmitted to the left rear wheel axle 22L and the right rear wheel axle 22R by the differential 20, whereby the left and right rear wheels 24RL and 24RR which are driving wheels are rotationally driven.
[0031]
On the other hand, the left and right front wheels 24FL and 24FR are both driven wheels and steered wheels, which are not shown in FIG. 1, but are rack and pinion type driven in response to steering of the steering wheel by the driver. It is steered via a tie rod by a power steering device.
[0032]
The braking forces of the left and right front wheels 24FL, 24FR and the left and right rear wheels 24RL, 24RR are controlled by controlling the braking pressures of the corresponding wheel cylinders 30FL, 30FR, 30RL, 30RR by the hydraulic circuit 28 of the braking device 26. Although not shown in FIG. 1, the hydraulic circuit 28 includes an oil reservoir, an oil pump, various valve devices, and the like, and the braking pressure of each wheel cylinder is normally driven according to the depression operation of the brake pedal 32 by the driver. It is controlled by the master cylinder 34, and if necessary, it is controlled by the behavior control electronic control device 36 as described in detail later.
[0033]
The behavior control electronic control unit 36 includes a signal indicating the longitudinal acceleration Gx of the vehicle from the longitudinal acceleration sensor 38, a signal indicating the lateral acceleration Gy of the vehicle from the lateral acceleration sensor 40, a signal indicating the yaw rate γ of the vehicle from the yaw rate sensor 42, and steering. A signal indicating the steering angle θf of the front wheel from the angle sensor 44, a signal indicating the actual steering angle δr of the rear wheel from the steering angle sensor 46, the left and right front wheels and the left and right rear from the wheel speed sensor 48i (i = fl, fr, rl, rr). A signal indicating the wheel speed (circumferential speed) Vwi of the wheel is input.
[0034]
Further, when the acceleration slip of the rear wheel 24RL or 24RR that is the drive wheel is excessive, the braking pressure of the left and right rear wheel cylinders 30RL and 30RR is detailed later by the electronic controller 50 for traction control in order to reduce the acceleration slip. The control is performed as described below. A signal indicating the wheel speed Vwi of each wheel is input to the traction control electronic control unit 50 from the behavior control electronic control unit 36, and the electronic control unit 50 is to perform the traction control for the left rear wheel or the right rear wheel. Is output to the electronic control unit 36.
[0035]
The behavior control electronic control device 36 and the traction control electronic control device 50 may actually comprise a microcomputer having a known configuration including a CPU, a ROM, a RAM, and an input / output port device and a drive circuit. The longitudinal acceleration sensor 38 detects the longitudinal acceleration with the vehicle acceleration direction as positive, and the lateral acceleration sensor 40, the yaw rate sensor 42, and the steering angle sensors 44 and 46 detect the lateral acceleration and the like with the left turning direction of the vehicle as the positive. It has become.
[0036]
The behavior control electronic control device 36 stores the control flow of FIGS. 2 to 6 and the maps of FIGS. 8 to 11 as described later, and based on the parameters detected by the above-described various sensors as described later. Various calculations are performed to determine the spin state amount SS for determining the turning behavior of the vehicle, the grip state index values Gγ and Ggy are determined, and the side slip state of the vehicle is determined based on the spin state amount and the grip state index value. Based on the determination result, the braking force of each wheel is controlled to control the turning behavior, and the alarm device 52 is activated as necessary.
[0037]
On the other hand, the electronic controller 50 for traction control calculates a vehicle speed Vb as a control reference based on the wheel speeds Vwfl and Vwfr of the left and right front wheels 24FL and 24FR which are driven wheels, and the acceleration slip of the left and right rear wheels based on the vehicle speed Vb. Sdrl and Sdrr are calculated, and when the acceleration slip is equal to or greater than a reference value, a braking force corresponding to the acceleration slip is applied to the corresponding wheel to perform traction control for reducing the acceleration slip.
[0038]
Next, a vehicle behavior control routine will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch not shown in the figure, and is repeatedly executed at predetermined time intervals. In the flowchart shown in FIG. 2, flag F relates to whether or not the vehicle is in a non-grip state, and 1 indicates that the vehicle is in a non-grip state.
[0039]
First, at step 10, a signal indicating the longitudinal acceleration Gx of the vehicle is read from the longitudinal acceleration sensor 38, and at step 20, the vehicle speed is determined in a manner known in the art based on the wheel speed Vwi. (Vehicle speed) is calculated, and the deviation of the lateral acceleration, that is, the vehicle slip acceleration Vyd, is calculated as a deviation Gy−V * γ of the product V * γ of the lateral acceleration Gy and the vehicle speed V and the yaw rate γ. In this case, the side-slip acceleration Vyd is integrated to calculate the side-slip speed Vy of the vehicle body. Calculated.
[0040]
In step 40, the spin amount SV is calculated as a linear sum K1 * β + K2 * Vyd of the vehicle body slip angle β and side slip acceleration Vyd, with K1 and K2 being positive constants. In step 50, the sign of the yaw rate γ is calculated. The spin direction amount SS is calculated as SV when the vehicle is turning left, and -SV when the vehicle is turning right, and the spin state amount is 0 when the calculation result is negative. It is said. The spin amount SV may be calculated as a linear sum of the vehicle body slip angle β and its differential value βd.
[0041]
In step 60, it is determined whether or not the flag F is 1, that is, whether or not the vehicle is in a non-grip state. If an affirmative determination is made, the amount of spin state is determined in step 80. Based on SS, the spin control amount Rsspin, which is the target slip ratio of the entire vehicle, is calculated from the map corresponding to the graph shown in FIG. 10, and when a negative determination is made, the routine proceeds to step 70.
[0042]
In step 70, it is determined whether or not both the left and right rear wheels 24RL and 24RR are under traction control. If an affirmative determination is made, the process proceeds to step 80. If a negative determination is made, the process proceeds to step 80. At 90, the spin control amount Rsspin is set to zero.
[0043]
In step 100, it is determined whether or not the spin control amount Rsspin is 0, that is, whether or not the behavior of the vehicle is stable and the behavior control is unnecessary. After each valve device of the hydraulic circuit 28 is controlled to the non-control position in step 110, the process returns to step 10, and when a negative determination is made, in step 120, the turning outer front wheel and the turning inner front wheel according to the following formula 5: The target slip ratios Rsfo, Rsfi, Rsro, Rsri for the rear outer wheel and the inner rear wheel are calculated.
Rsfo = Rsspin
Rsfi = 0
Rsro = -Rsspin / 2
Rsri = -Rsspin / 2 (5)
[0044]
In step 130, the turning direction of the vehicle is determined based on the sign of the yaw rate γ to identify the turning inner and outer wheels, and the final target slip ratio Rsi (i = fr, fl, rr) of each wheel is determined based on the identification result. , Rl) is calculated. That is, the final target slip ratio Rsi is obtained according to the following equations 6 and 7, respectively, for the case of left turn and right turn of the vehicle.
Rsfr = Rsfo
Rsfl = Rsfi
Rsrr = Rsro
Rsrl = Rsri (6)
Rsfr = Rsfi
Rsfl = Rsfo
Rsrr = Rsri
Rsrl = Rsro (7)
[0045]
In step 140, the braking force of each wheel is controlled by, for example, wheel speed feedback control so that the slip rate of each wheel becomes the final target slip rate Rsi, thereby suppressing the spin state of the vehicle and stabilizing the behavior of the vehicle. Then, the process returns to step 10. In this case, when the final target slip ratio is a positive value, the pressure of the wheel cylinder of the corresponding wheel is increased, and when the final target slip ratio is a negative value, the pressure of the wheel cylinder of the corresponding wheel is reduced. The
[0046]
Next, a routine for calculating the estimated value μg of the road friction coefficient will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 3 is executed by interruption every predetermined time.
[0047]
First, in step 210, a signal indicating the lateral acceleration Gy of the vehicle detected by the lateral acceleration sensor 78 is read, and in step 220, the vehicle for calculating the estimated value μg of the friction coefficient of the road surface. Horizontal acceleration Gxy is calculated according to the following equation (8).
Gxy = (Gx ² + Gy ² ) ^1/2 ...... (8)
[0048]
In step 230, it is determined whether or not the horizontal acceleration Gxy exceeds the horizontal acceleration Gxy (n-1) one cycle before. If an affirmative determination is made, the coefficient K is 1 in step 240. When a negative determination is made, the coefficient K is set to 0.01 in step 250. In step 260, the estimated value μg of the friction coefficient of the road surface is calculated according to the following equation (9).
μg = (1-K) * μg (n-1) + K * Gxy (9)
[0049]
In the illustrated embodiment, the friction coefficient of the road surface is calculated as the square sum of squares of Gx and Gy, but may be estimated from the absolute value of the lateral acceleration Gy of the vehicle. The lateral acceleration components Gyfy and Gyry at the front wheel position and the rear wheel position generated by yawing are calculated, and the sum of these components and the vehicle lateral acceleration Gy is the lateral acceleration component Gyf at the front wheel position and the rear wheel position. Gyr is calculated, and the larger value of Gyf and Gyr may be calculated as the lateral acceleration Gys and may be calculated as the square sum of squares of Gx and Gys.
[0050]
Next, a flag F setting routine, that is, a vehicle grip state determination routine will be described with reference to the flowcharts shown in FIGS. The control according to the flowcharts shown in FIGS. 4 and 5 is also executed by interruption every predetermined time.
[0051]
In step 310 of this routine, a signal indicating the steering angle .theta.f is read, and in steps 320 and 330, as shown in FIGS. 9 and 10, respectively, based on the longitudinal speed Vx (= V) of the vehicle. The low speed processing coefficients Ka and Kb are calculated from the map corresponding to the graph.
[0052]
In step 340, the first parameter corresponding to the deviation between the slip angle of the front wheels and the slip angle of the rear wheels, that is, the steering angle deviation ΔSγ based on the yaw rate γ is calculated according to the following equation (10).
ΔSγ = {θf−δr * N− (N * L / Vx) * γ} * Ka (10)
[0053]
In step 350, the second parameter corresponding to the deviation between the slip angle of the front wheels and the slip angle of the rear wheels, that is, the steering angle deviation ΔSgy based on the lateral acceleration Gy is calculated according to the following equation (11).
ΔSgy = {θf−δr * N− (N * L / Vx ² ) * Gy} * Kb (11)
[0054]
In step 360, the dead zone set value μgm is calculated from the map corresponding to the graph shown in FIG. 11 on the basis of the road friction coefficient μg calculated in accordance with the flowchart shown in FIG. The grip state index value Gγ based on the first parameter is calculated according to the following equation 12 with Kc as a positive constant.
Gγ = (| ΔSγ | −μgm) * Kc (12)
[0055]
In step 380, it is determined whether or not the grip state index value Gγ is negative. If a negative determination is made, the process proceeds directly to step 400. If an affirmative determination is made, the grip is determined in step 390. The state index value Gγ is set to 0.
[0056]
In step 400, the grip state index value Ggy based on the second parameter is calculated according to the following equation 13 with Kd being a positive constant. In step 400, it is determined whether or not the index value Ggy is negative. When a negative determination is made, the process proceeds to step 430 as it is. When an affirmative determination is made, the index value Ggy is set to 0 in step 420. Since the dead zone set value μgm increases as the road surface friction coefficient μg increases, the grip state index values Gγ and Ggy decrease as the road surface friction coefficient increases.
Ggy = (| ΔSgy | −μgm) * Kd (13)
[0057]
In step 430, it is determined whether or not the grip state index value Gγ exceeds the reference value Gγ1 (positive constant), that is, whether or not the determination based on the first parameter is the non-grip state. If the determination is affirmative, the flag F1 is set to 1 in step 440. If the determination is negative, the flag F1 is reset to 0 in step 450.
[0058]
In step 460, it is determined whether or not the grip state index value Ggy exceeds the reference value Ggy1 (positive constant), that is, whether or not the determination based on the second parameter is the non-grip state. When a positive determination is made, the flag F2 is set to 1 at step 470, and when a negative determination is made, the flag F2 is reset to 0 at step 480.
[0059]
In step 490, it is determined whether or not the flag F1 is 1 and the flag F2 is 1, that is, whether both the determination based on the first parameter and the determination based on the second parameter are in the non-grip state. When a negative determination is made, the process proceeds to step 530. When an affirmative determination is made, the count value C1 of the counter is incremented by 1 in step 500.
[0060]
In step 510, it is determined whether or not the count value C1 exceeds the reference value t1 (a positive constant), that is, in a non-grip state by both the determination based on the first parameter and the determination based on the second parameter. It is determined whether or not the state in which the determination is made has continued for a predetermined time or more. When a negative determination is made, this routine is ended as it is. When an affirmative determination is made, a flag is set in step 520. F is set to 1.
[0061]
In step 530, the count value C1 is reset to 0. In step 540, it is determined whether or not the flag F is 1. If negative determination is made, the process proceeds to step 570 as it is. When the determination is made, the process proceeds to step 550.
[0062]
In step 550, it is determined whether or not the flag F1 is 0. When an affirmative determination is made, the count value C2 of the counter is incremented by 1 in step 560, and when a negative determination is made. In step 570, the count value C2 is reset to zero.
[0063]
In step 580, it is determined whether or not the count value C2 exceeds the reference value t2 (positive constant), that is, based on the determination based on the first and second parameters, it is determined that the state is the non-grip state. After that, it is determined whether or not the state in which the determination of the grip state is performed by the determination based on the first parameter has continued for a predetermined time or more, and when a negative determination is made, the routine is terminated as it is, If a positive determination is made, the flag F is reset to 0 in step 590.
[0064]
According to the grip state determination routine of the illustrated embodiment, steering is performed as the first parameter corresponding to the deviation between the slip angle of the front wheel and the slip angle of the rear wheel based on the steering angle θf and the yaw rate γ in steps 320 and 340. An angular deviation ΔSγ is calculated, a grip state index value Gγ based on the steering angle deviation ΔSγ and the road friction coefficient μg is calculated in steps 360 to 390, and non-based on the grip state index value Gγ in steps 430 to 450. It is determined whether or not the vehicle is in the grip state. When the vehicle is in the non-grip state, the flag F1 is set to 1.
[0065]
Similarly, in steps 330 and 350, the steering angle deviation ΔSgy is calculated as a second parameter corresponding to the deviation between the slip angle of the front wheels and the slip angle of the rear wheels based on the steering angle θf and the lateral acceleration Gy. In steps 400 to 420, a grip state index value Ggy based on the steering angle deviation ΔSgy and the road surface friction coefficient μg is calculated. In steps 460 to 480, it is determined whether or not the vehicle is in the non-grip state based on the grip index value Ggy. A determination is made and the flag F2 is set to 1 when in the non-grip state.
[0066]
In step 490, it is determined whether or not both the determination based on the grip state index value Gγ and the determination based on the grip state index value Ggy are in the non-grip state. If it continues for more than the time, an affirmative determination is made in step 510 and the flag F is set to 1. In other words, when the steering angle deviation ΔSγ based on the steering angle and the yaw rate and the steering angle deviation ΔSgy based on the steering angle and the lateral acceleration are both greater than the deviation corresponding to the friction coefficient of the road surface, the non-grip is maintained. The state is determined.
[0067]
If the flag F1 or F2 is set to 0 after the flag F is set to 1, that is, if either the determination based on the grip state index value Gγ or the determination based on the grip state index value Ggy is in the grip state, step 490 is performed. In step 540, a negative determination is made, and in step 550, a determination is made as to whether or not the flag F1 is 0. If the flag F1 is 0, the state is not less than a predetermined time. If this is continued, the flag F is reset to 0 in step 590.
[0068]
Therefore, once it is determined that the vehicle is in the non-grip state by both determinations based on the first and second parameters, the steering angle deviation ΔSγ based on the steering angle and the yaw rate is smaller than the deviation corresponding to the friction coefficient of the road surface. The grip state is determined when the state continues for a predetermined time or more.
[0069]
Next, the alarm processing routine will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 6 is also executed by interruption every predetermined time.
[0070]
In step 710 of this routine, it is determined whether or not the flag F is 1, that is, whether or not the vehicle is in a non-grip state. If a negative determination is made, this routine is terminated as it is. If the determination is affirmative, the routine proceeds to step 720.
[0071]
In step 720, it is determined whether or not the vehicle speed V exceeds the reference value Vo, that is, whether or not the vehicle is running at a speed higher than a predetermined vehicle speed. When the routine is finished and an affirmative determination is made, in step 730, the alarm device 90 is activated, and an alarm to the driver that the vehicle is in a non-grip state is issued.
[0072]
Next, the traction control in the illustrated embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 7 is also executed by interruption every predetermined time.
[0073]
First, at step 810, a signal indicating the wheel speed Vwi of each wheel is inputted from the behavior control electronic control device 36, and at step 820, the wheel speeds Vwfl and Vwfr of the left and right front wheels 24FL and 24FR which are driven wheels are inputted. Based on this, a vehicle speed Vb that is a reference for traction control is calculated in a manner known in the art.
[0074]
In step 830, acceleration slips Sdrl and Ddrr of the left and right rear wheels are calculated according to the following equations 14 and 15 based on the vehicle body speed Vb.
Sdrl = Vwrl−Vb (14)
Sdrr = Vwrr-Vb (15)
[0075]
In step 840, it is determined whether or not the acceleration slip Sdrl of the left rear wheel is greater than or equal to a reference value Sdo (positive constant). If a negative determination is made, the process proceeds to step 860 as it is and an affirmative determination is made. When this is done, in step 850, the left rear wheel is controlled with a braking force corresponding to the acceleration slip Sdrl, whereby traction control is performed to reduce the acceleration slip for the left rear wheel.
[0076]
In step 860, it is determined whether or not the acceleration slip Sdrr of the right rear wheel is greater than or equal to the reference value Sdo. If a negative determination is made, the process returns to step 810, and if an affirmative determination is made, the process returns to step 810. In 870, the right rear wheel is controlled with a braking force corresponding to the acceleration slip Sdrr, whereby traction control is performed to reduce the acceleration slip for the right rear wheel.
[0077]
It should be noted that spin suppression control as vehicle side slip state suppression control, vehicle grip state determination itself, and traction control itself do not form the gist of the present invention, and these control and determination are arbitrary known in the art. It may be done as follows. For example, in the traction control of the illustrated embodiment, when the acceleration slips Sdrr and Sdrl of the drive wheel are equal to or greater than the reference value Sdo, the drive wheel is controlled with a braking force corresponding to the acceleration slip. However, when the acceleration slip becomes equal to or higher than the first reference value Sdo1, traction control is started in which the drive wheel is controlled with a braking force corresponding to the acceleration slip, and the acceleration slip is smaller than the first reference value Sdo1. It may be modified so that the traction control is terminated when it becomes less than the reference value Sso2.
[0078]
Thus, in the illustrated embodiment, the lateral slip acceleration Vyd of the vehicle body is calculated in step 20, the slip angle β of the vehicle body is calculated in step 30, and the spin amount is calculated as a linear sum of these in step 40. SV is calculated, and in step 50, the spin state amount SS is calculated as a value obtained by making the spin amount SV an absolute value.
[0079]
In step 60, it is determined whether or not the vehicle is in the non-grip state. If it is determined that the vehicle is in the non-grip state, the determination is made in step 80 based on the spin state quantity SS. If the spin control amount Rsspin is calculated from the map corresponding to the graph shown in FIG. 6 and it is determined that the vehicle is in the grip state, whether or not the left and right rear wheels are under traction control in step 70. Is determined.
[0080]
When it is determined in step 70 that at least one of the left and right rear wheels is not in traction control, the spin control amount Rsspin is set to 0 in step 90, but the left and right rear wheels are in traction control. When it is determined that the medium is in the middle, in step 80, the spin control amount Rsspin is calculated from the map corresponding to the graph shown in FIG. Further, in step 100, it is determined whether or not the turning behavior of the vehicle is stable based on the spin control amount Rsspin.
[0081]
When the turning behavior of the vehicle is in a stable state, an affirmative determination is made in step 100, whereby each valve device of the hydraulic circuit 28 is controlled to the non-control position in step 110, and then the process returns to step 10. Therefore, in this case, the behavior control in steps 120 to 140 is not executed, and thereby the braking force of each wheel is controlled according to the depression amount of the brake pedal 32 by the driver.
[0082]
When the turning behavior of the vehicle is in the spin state, a negative determination is made in step 100, the final target slip ratio Rsi of each wheel is calculated in steps 120 and 130, and in step 140, each wheel's final slip ratio Rsi is calculated. The braking force of each wheel is controlled so that the target slip ratio becomes the final target slip ratio Rsi.
[0083]
Therefore, according to the illustrated embodiment, when it is determined that the vehicle is in the spin state and the vehicle is determined to be in the non-grip state, the spin suppression control is executed to reduce the vehicle spin state and stabilize the vehicle behavior. If the vehicle is determined to be in a spin state, the vehicle is determined to be in a grip state, and it is determined that at least one of the left and right rear wheels is not in traction control, unnecessary spin suppression is performed. It is possible to prevent the control from being executed, and even if it is determined that the vehicle is in a spin state and the vehicle is in a grip state, the left and right rear wheels are in traction control. When the determination is made, necessary spin suppression control can be executed to reduce the vehicle spin state and stabilize the vehicle behavior.
[0084]
In general, even in a situation where one of the left and right rear wheels is traction controlled, a certain lateral force is secured by a wheel opposite to the left and right wheels, and one of the left and right rear wheels is instantaneously In a situation where traction control is performed, the lateral force of the wheel immediately recovers due to traction control, so even if it is determined that the vehicle is in a spin state and the vehicle is in a grip state, the left and right rear wheels Spin suppression control is executed in the situation where only one of the traction is controlled Is Preferably not.
[0085]
According to the illustrated embodiment, even when it is determined that the vehicle is in the spin state and the vehicle is in the grip state, only one of the left and right rear wheels is traction controlled. Since a negative determination is made in 70, the spin control amount Rsspin is set to 0 in step 90, so that unnecessary spin suppression control is reliably prevented from being executed in such a situation. Can do.
[0086]
Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.
[0087]
For example, in the above-described embodiment, the vehicle is a rear wheel drive vehicle, but the vehicle to which the present invention is applied may be, for example, a four wheel drive vehicle.
[0088]
In the above-described embodiment, the target slip ratio for spin control is calculated according to the above equation 5, and the braking force of the left and right rear wheels is reduced. This may be achieved by applying a braking force to the front outer wheel without changing the braking force.
[0089]
In the above-described embodiment, whether or not the vehicle is in the non-grip state is determined based on both the steering angle deviation ΔSγ as the first parameter and the steering angle deviation ΔSgy as the second parameter. However, the determination of the non-grip state based on the second parameter may be omitted if necessary. In that case, Steps 330, 350, 400 to 420, 460 to 480 are omitted. In Step 490, it is determined whether or not the flag F1 is 1, and Steps 540 to 580 are omitted.
[0090]
In the above-described embodiment, it is determined whether or not the vehicle speed V exceeds the reference value Vo in the alarm processing routine, but this determination step is omitted if necessary. Also good. However, when the vehicle has a very low friction coefficient such as an icy and snowy road surface, it is likely to be in a non-grip state when the vehicle starts, and if the vehicle speed discrimination is omitted, the alarm device is activated more frequently and the driver feels troublesome. In some cases, it is preferable to determine the vehicle speed as in the illustrated embodiments in order to solve such a problem.
[0091]
【The invention's effect】
As is clear from the above description, according to the configuration of claim 1 of the present invention, even when the side slip state of the vehicle is estimated, when the vehicle is in the grip state, the side slip state suppression control by the side slip suppression means is performed. Is prohibited, it is possible to prevent the side slip state suppression control from being performed unnecessarily, and it is determined that the vehicle is in the grip state. For both the left and right drive wheels When the acceleration slip suppression control by the acceleration slip control means is executed and the side force of the driving wheel is reduced, the side slip state suppression control by the side slip suppression means is permitted, so the side force of the drive wheel decreases and the vehicle slips. When the vehicle is judged to be in the grip state, it is possible to surely suppress the side slip state of the vehicle by executing the side slip state suppression control by the side slip suppression means in a situation where the vehicle is easily gripped. About at least one of the left and right drive wheels When the acceleration slip suppression control by the acceleration slip control means is not executed, the side slip state suppression control by the side slip suppression means is prohibited, In situations where there is a low risk of vehicle skidding compared to when the lateral forces on both the left and right drive wheels are reduced It is possible to prevent unnecessary skid state suppression control from being executed.
[0093]
And claims 2 According to the configuration, since the driving wheels are the left and right rear wheels, the vehicle spin state due to the reduction of the lateral force due to the braking force applied to the left and right rear wheels by the acceleration slip suppression control Can be reliably suppressed.
[0094]
And claims 3 With this configuration, since the side slip of the vehicle is suppressed by individually controlling the braking force of the wheel, the braking force is applied to the wheels other than the wheel to which the braking force is applied by the acceleration slip suppression control. It is possible to reliably suppress the side slip state of the vehicle by applying a moment for suppressing the side slip.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram (A) and a block diagram (B) of a control system showing one embodiment of a behavior control device according to the present invention applied to a rear wheel drive vehicle.
FIG. 2 is a flowchart showing a behavior control routine in the embodiment.
FIG. 3 is a flowchart showing a calculation routine of an estimated value μg of a road surface friction coefficient in the embodiment.
FIG. 4 is a flowchart showing the first half of a vehicle grip state determination routine in the embodiment;
FIG. 5 is a flowchart showing the second half of the vehicle grip state determination routine in the embodiment;
FIG. 6 is a flowchart showing an alarm processing routine in the embodiment.
FIG. 7 is a flowchart showing a traction control routine in the embodiment.
FIG. 8 is a graph showing a relationship between a spin state amount SS and a spin control amount Rsspin.
FIG. 9 is a graph showing a relationship between a longitudinal speed Vx and a low speed processing coefficient Ka.
FIG. 10 is a graph showing a relationship between a longitudinal speed Vx and a low speed processing coefficient Kb.
FIG. 11 is a graph showing a relationship between a friction coefficient μg of a road surface and a dead zone set value μgm.
[Explanation of symbols]
10 ... Engine
16 ... Automatic transmission
28 ... Hydraulic circuit
30FL, 30FR, 30RL, 30RR ... Wheel cylinder
34 ... Master cylinder
36. Electronic control device for behavior control
38. Longitudinal acceleration sensor
40 ... Lateral acceleration sensor
42 ... Yaw rate sensor
44, 46: Steering angle sensor
48FL to 48RR ... Wheel speed sensor
50. Electronic control device for traction control

Claims (3)

Means for estimating the side slip state of the vehicle, side slip suppression means for executing side slip state suppression control when the side slip state of the vehicle is estimated, and grip state determination means for determining whether or not the vehicle is in a grip state with respect to the road surface And a determination means for determining whether or not the side slip state suppression control by the side slip suppression means is possible. When the acceleration slip of the drive wheel is excessive, the vehicle applies a braking force to the drive wheel. Accelerating slip control means for executing the acceleration slip suppression control, and the determination means permits the side slip state suppression control by the side slip suppression means when the grip state determination means determines that the vehicle is in a non-grip state. and, sometimes the acceleration slip control means vehicle by the gripping state judgment means is judged to be in the grip state Only when the wheel is Ri acceleration slip suppression control yo is the left and right driving wheels both allow skidding state suppression control by the side slip suppressing means determines that the vehicle is in a gripping state by the gripping state judgment unit In such a case, when at least one of the left and right drive wheels is not subjected to the acceleration slip suppression control by the acceleration slip control means, the side slip state suppression control by the side slip suppression means is prohibited. Control device. 2. The vehicle behavior control device according to claim 1 , wherein the driving wheels are left and right rear wheels. The vehicle behavior control device according to claim 1 or 2 , wherein the side slip suppression means is configured to suppress a side slip of the vehicle by individually controlling a braking force of a wheel.

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