JP3736370B2

JP3736370B2 - Vehicle steering system

Info

Publication number: JP3736370B2
Application number: JP2001063403A
Authority: JP
Inventors: 晴彦佐藤
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 2001-03-07
Filing date: 2001-03-07
Publication date: 2006-01-18
Anticipated expiration: 2021-03-07
Also published as: JP2002264831A

Description

【０００１】
【発明の属する技術分野】
本発明は、車速に応じて舵角比が変化する車両用操舵装置に関し、特に加減速時の車両軌道の膨らみ、巻き込みに対する操舵力補正を行う車両用操舵装置に関する。
【０００２】
【従来の技術】
車両状態に応じて舵角比（前輪舵角度／ステアリング操舵角度）を変化させる車両用操舵装置として、特開平１１−３３４６２７号公報によるものが開示されている。この車両用操舵装置による舵角比は、車速に対して変化し、低車速時に舵角比は大きく、車速が上がるにつれ徐々に舵角比は小さくなる。舵角比が車速に応じて変化するため、操舵角一定で加減速を行う車両は、舵角比固定の車両に対して加速旋回時は外側に膨らみ、減速旋回時は内側に巻き込むという特性を持つ。このような従来の車両用操舵装置では、加減速度に応じて舵角比の補正が行われる。
【０００３】
【発明が解決しようとする課題】
しかし、従来装置では、加減速時に舵角比を変化させるので、舵角比一定の車両に比べて、ステアリング操舵角度に対する車両の反応が変るため、運転者が違和感を感じる可能性がある。また、加減速から一定車速に戻る場合にも、変化していた舵角比が一定となるため、同様に運転者が違和感を感じる可能性がある。
【０００４】
本発明は、加減速旋回時にも舵角比は車速に応じて変化するという特性を保ちながら、運転者が加速時の車両軌道の膨らみ、減速時の車両軌道の巻き込みに対する修正操舵を自然に行うことができる車両用操舵装置を提供することを目的とする。
【０００５】
【課題を解決するための手段】
本発明による車両用操舵装置の一実施の形態を図１に示す。
（１）請求項１の発明による車両用操舵装置は、ステアリングホイール１の操舵角から前輪舵角の伝達比である舵角比を車速に応じて変更する舵角比可変装置３と、ステアリングホイール１が操舵されたときにそのステアリングホイール１を中立方向へ復帰させる操舵力を調節する操舵力調節装置５と、現在の車両状態から一定時間後の車両状態を算出する車両状態予測装置５と、算出された車両状態に基づいて操舵力を算出する操舵力算出装置５と、算出された操舵力となるよう操舵力調節装置４を制御して操舵力を補正する制御装置５と、車速を検出する車速検出装置７とを備え、車両状態予測装置５は、検出された車速に基づいて現在の車速の加減速度を算出するとともに、その加減速度から一定時間後の車速を算出し、検出された現在の車速から算出された一定時間後の車速までの舵角比の差ΔＧを算出し、操舵力算出装置５は、舵角比の差ΔＧから補正操舵力を算出し、予め定めた基準操舵力をこの補正操舵力で補正することにより上述した目的を達成する。
（２）請求項２の発明は、請求項１の車両用操舵装置において、舵角比は車速が増加するにつれて小さくなり、制御装置５は、加速時には操舵力が小さく、減速時には操舵力が大きくなるよう操舵力調節装置４を制御して操舵力補正を行うことを特徴とする。
（３）請求項３の発明は、請求項２の車両用操舵装置において、ステアリングホイール１の操舵角を検出する操舵角度検出装置６をさらに設け、制御装置５は、検出された操舵角に基づいて、加速時にあってはステアリングホイール１の操舵角が一定またはステアリングホイール１が切り増し操作された場合に、減速時にあってはステアリングホイール１の操舵角が一定またはステアリングホイール１が切り戻し操作された場合にそれぞれ操舵力補正を行うことを特徴とする。
（４）請求項４の発明は、請求項２の車両用操舵装置において、舵角比の差ΔＧに応じて変化する操舵力の補正量は、加速時よりも減速時の方が大きいことを特徴とする。
（５）請求項５の発明は、請求項１の車両用操舵装置において、ステアリングホイール１の操舵角を検出する操舵角度検出装置６をさらに設け、制御装置５は、検出されたステアリング操舵角に基づいてステアリング角速度を算出し、算出されたステアリング操舵角速度が一定値以下と判定したときに操舵力補正を行うことを特徴とする。
（６）請求項６の発明による車両用操舵装置は、ステアリングホイール１の操舵角から前輪舵角の伝達比である舵角比を車速に応じて変更する舵角比可変装置３と、ステアリングホイール１が操舵されたときにそのステアリングホイール１を中立方向へ復帰させる操舵力を調節する操舵力調節装置５と、現在の車両状態から一定時間後の車両状態を算出する車両状態予測装置５と、算出された車両状態に基づいて操舵力を算出する操舵力算出装置５と、算出された操舵力となるよう操舵力調節装置４を制御して操舵力を補正する制御装置５と、車速を検出する車速検出装置７と、ステアリングホイール１の操舵角を検出する操舵角度検出装置６とを備え、車両状態予測装置５は、舵角比、検出された車速、車速から算出された加減速度、検出されたステアリング操舵角および操舵角から算出されたステアリング操舵角速度に基づいて、現車速を維持した場合の一定時間後の車両位置と車両角度、および現加減速度を維持した場合の一定時間後の車両位置と車両角度の差である車両状態偏差を算出し、制御装置５は、算出された車両状態偏差に応じて補正操舵力を算出し、予め定めた基準補正操舵力をこの補正操舵力で補正することにより上述した目的を達成する。
（７）請求項７の発明は、請求項６の車両用操舵装置において、舵角比は、車速が増加するにつれて小さくなり、制御装置５は、加速時には操舵力が小さく、減速時には操舵力が大きくなるよう操舵力調節装置４を制御して操舵力補正を行うことを特徴とする。
（８）請求項８の発明は、請求項６の車両用操舵装置において、制御装置５は、加速時にあっては現車速を維持した場合の車両位置より、現加速度を維持した場合の車両位置が外側（カーブ旋回で膨らむ方向）である場合、および減速時にあっては現車速を維持した場合の車両位置より、現減速度を維持した場合の車両位置が内側（カーブ旋回で巻き込む方向）である場合にそれぞれ操舵力補正を行うことを特徴とする。
（９）請求項９の発明は、請求項６の車両用操舵装置において、制御装置５は、車両状態偏差が一定または減少傾向にある場合に操舵力補正を行うことを特徴とする。
（１０）請求項１０の発明は、請求項６の車両用操舵装置において、制御装置５は、ステアリング操舵角速度が一定値以下の場合に操舵力補正を行うことを特徴とする。
【０００６】
なお、本発明の構成を説明する、上記課題を解決するための手段の項では、本発明をわかりやすく説明するために実施の形態の図を用いたが、これにより本発明が実施の形態に限定されるものではない。
【０００７】
【発明の効果】
本発明によれば、車速によって舵角比が変化する車両用操舵装置において、現在の車両状態と一定時間後の車両状態に基づいて操舵力を算出し、操舵力補正を行うようにしたので、運転者が加減速時の車両軌道の膨らみ、巻き込みに対する修正操舵を自然に行うことができる。
【０００８】
【発明の実施の形態】
《第１の実施の形態》
本発明による車両用操舵装置の第１の実施の形態を図１に示す。この車両用操舵装置は、ステアリングホイール１と、このステアリングホイール１とラックアンドピニオン機構２との間に設けられた舵角比可変装置３および操舵力調節装置４と、舵角比可変装置３による舵角比および操舵力調節装置４による操舵力を変更制御する制御装置５とを有する。制御装置５からの命令量に応じて、舵角比可変装置３は舵角比を任意に設定でき、操舵力調節装置４は操舵力を任意に調節できる。ここで、操舵力調節装置４は電動モータ等によりセルフアライニングトルクを人工的に発生させて、車両が旋回するときにステアリングホイール１を中立状態に戻す方向の力つまり操舵力を調節することができる。制御装置５には、操舵角度検出装置６により検出されるステアリングホイール１の操舵角と、車速検出センサ７により検出される車速と、イグニションスイッチ８により検出されるイグニションキーのオン・オフ状態とが入力される。
【０００９】
図２は、車速に対する舵角比の特性を示す。舵角比は、一定車速ＶＬ以下のとき最大値Ｇmaxで一定、車速ＶＬ以上になると徐々に低下していく。そのため、操舵角一定で加減速を行う場合、通常の舵角比固定の車両に対して加速旋回時は外側に膨らみ、減速旋回時は内側に巻き込むという特性を持つ。
【００１０】
本発明による車両用操舵装置は、加速旋回時の膨らみ、減速旋回時の巻き込みに対する修正操舵を助けるもので、加減速度に応じて操舵力を変化させるものである。なお、本発明の実施の形態においては、加減速時以外では操舵力補正を行わない。
【００１１】
加速旋回時には操舵力を小さくし、運転者が切り増し操作を行う際、ステアリングホイール１を軽く操作できるようにし、減速旋回時には操舵力を大きくし、運転者が切り戻し操作を行う際、ステアリングホイール１を軽く操作できるようにする。操舵力は、現在と一定時間後の車両状態、例えば舵角比等の差に基づいて算出する（操舵力算出装置）。以下、その算出方法について説明する。
【００１２】
現在の加減速度を維持した場合の一定時間先の舵角比を予測し（車両状態予測装置）、この予測舵角比と現在の舵角比との差に応じて操舵力を増減させる。一定時間先までの舵角比差を取る理由は、加減速度に対する現在の舵角比の変化勾配に応じて操舵力を補正する方法では、運転者の反応が遅れる可能性があるためである。本発明の実施の形態では、運転者の操作の遅れを考慮して、一定時間先まで予測して操舵力の補正量を決定する。
【００１３】
図２に示すように、現在の車速をＶ０、その減速度を維持した場合の時間Ｔｃ後の車速をＶ１とした場合、舵角比はＧ０からＧ１に増加する。ここで、車速Ｖ１は、車速Ｖ０の時系列データより算出した加減速度Ｖ０ｄを用い、以下の式により算出される。
【数１】
Ｖ１＝Ｖ０＋Ｔｃ・Ｖ０ｄ（式１）
【００１４】
図３に、車速Ｖに対する舵角比の変化量Ｇ'を示す。これは、図２の車速Ｖに対する舵角比Ｇの特性を微分したものである。図３における、車速Ｖ０から車速Ｖ１までの面積(積分値)が、現在から時間Ｔｃまでの舵角比の差である。この面積の単位時間量を△Ｇ(以下、舵角比予測変化量と呼ぶ)とすると、以下で表すことができる。
【数２】

符号は、減速時は−、加速時は＋になる。
【００１５】
操舵力Ｆは、予め定められた、一定速走行時にステアリングホイールの操舵角を一定に保つのに必要な力（以下、基準操舵力とする）Ｆ’に、以下で導出する操舵力の補正値（以下、基本補正操舵力とする）ΔＦ’を足したものとする。
【００１６】
図４に、舵角比予測変化量△Ｇと、基本補正操舵力△Ｆ'との関係を示す。舵角比予測変化量△Ｇが０近辺（−Ｇｓ≦ΔＧ≦Ｇｓ）では、エンジンブレーキ等の微少加減速に対して反応しないようにするため、基本補正操舵力ΔＦ’をゼロとする。つまり不感帯を設ける。Ｇ＜−ＧｓおよびＧｓ＜Ｇの場合は、舵角比予測変化量△Ｇと基本補正操舵力△Ｆ'は比例する関係としている。ただし、加速時（舵角比予測変化量△Ｇが＋）と減速時（舵角比予測変化量△Ｇが−）の場合で、この比例勾配を変化させている。これは、加速旋回時の切り増し操作に比べ、減速旋回時の切り戻し操作の方が運転操作が難しいためであり、減速旋回時に大きな操舵力が得られるよう、この比例勾配を大きくしている。
【００１７】
また、加速旋回時の膨らみ、減速旋回時の巻き込みに対する修正操舵操作は、ステアリングホイール１の操作としては比較的ゆっくりな操作であり、それよりも速いステアリングホイール１の操作は、車両が一定旋回軌道で走行中ではない場合のステアリングホイール１の操作とみなし、操舵力の補正を行わないものとする。ここで、ステアリングホイールの操作の速度を表す値として、操舵角速度θｓｄを用いる。
【００１８】
図５に、操舵角速度の絶対値｜θｓｄ｜と操舵力補正量の係数Ｋｆの関係を示す。操舵力補正量の係数Ｋｆは、前述の基本補正操舵力△Ｆ'に掛ける係数である。操舵角速度の絶対値｜θｓｄ｜が一定値以上の場合は、基本操舵力補正量の係数Ｋｆはゼロとし、操舵力補正を行わない。以上より、操舵力は次式で表される。
【数３】
操舵力Ｆ＝基準操舵力Ｆ'＋補正操舵力△Ｆ'×Ｋｆ (式３)
【００１９】
ここで、本発明による車両用操舵装置は、加速時は膨らみ、減速時は巻き込む現象に対する修正操作を助けるものであり、それ以外の操作の場合は補正を行わない。図６に操舵力補正を行う場合と行わない場合を示す。加速旋回時は、操舵角一定又は切り増しの場合、減速旋回時は、操舵角一定又は切り戻しの場合のみ操舵力補正を行う。
【００２０】
以上説明した手法で操舵力補正を行うための制御装置５の処理手順を図７のフローチャートに示す。
【００２１】
車速Ｖ０、操舵角度θｓを読み込む（ステップＳ１）。これらの値の時系列データと図６により、操舵力補正を行う状態か判断する（ステップＳ２）。ステップＳ３で、操舵力補正を行うと肯定判定された場合は、車速Ｖの時系列データより現在の加減速度Ｖ０ｄを求め（ステップＳ４）、（式１）により一定時間Ｔｃ後の車速Ｖ１を算出する（ステップＳ５）。
【００２２】
ステップＳ６において、図３の舵角変化量Ｇ'と（式２）により、舵角比予測変化量△Ｇを求める。この△Ｇと図４から、基本補正操舵力△Ｆ'を算出する（ステップＳ７）。次いで、図５から操舵角速度の絶対値｜θｓｄ｜により係数Ｋｆを求める（ステップＳ８）。基準操舵力Ｆ'、基本補正操舵力△Ｆ'、係数Ｋｆから（式３）により操舵力Ｆを導出する（ステップＳ９）。ステップＳ１０において、操舵力Ｆとなるように操舵力調節装置４を駆動する。
【００２３】
ステップＳ３において、操舵力補正を行わないと否定判定された場合は、操舵力Ｆ＝基準操舵力Ｆ’とし（ステップＳ１２）、ステップＳ１０において操舵力Ｆとなるように操舵力調節装置４を駆動する。
【００２４】
ステップＳ１１で、キーＯＦＦと肯定判定した場合はこの制御を終了し、否定判定した場合は、再びステップＳ１に戻り制御を継続する。
【００２５】
以上説明したように、第１の実施の形態による車両用操舵装置では、現在の舵角比と一定時間先の予測舵角比との差である舵角比予測変化量ΔＧに応じて基本補正操舵力を決定し、基準操舵力に基本補正操舵力を加減算することによって算出される操舵力となるように操舵力調節装置４を駆動し、操舵力補正を行うようにした。したがって、加減速旋回時に舵角比を変化させることなく、運転者が加速時の膨らみ、減速時の巻き込みに対する修正操舵を自然に行うことができる。また、図４に示す、舵角比予測変化量ΔＧと基本補正操舵力の関係において、加速旋回時に比べて運転操作の難しい減速旋回時に比例勾配が大きくなるようにしたので、減速旋回時に大きな操舵力が得られる。また、ステアリング操作がゆっくりであるときは、運転者が車両軌道の修正操舵を行っていると判断するようにしたので、修正操舵を行っているときに操舵力補正を行うことができる。さらに、加速旋回時に操舵角一定または切り増しの場合、減速旋回時に操舵角一定または切り戻しの場合のみ操舵力補正を行うようにしたので、修正操舵を行うときに操舵力補正を行うことができる。
【００２６】
《第２の実施の形態》
第１の実施の形態による車両用操舵装置は、基本補正操舵力ΔＦ’を加減速時の舵角比差ΔＧにより決定したが、第２の実施の形態による車両用操舵装置では、より詳細に車両状態を予測して基本補正操舵力ΔＦ’を求める。
【００２７】
第２の実施の形態による車両用操舵装置の構成は、図１に示す第１の実施の形態と同様であるが、制御装置５における処理内容が第１の実施の形態と異なる。以下では第１の実施の形態との相違点を主に説明する。
【００２８】
舵角比、車速、加減速度、ステアリング操舵角およびステアリング操舵角速度から、一定時間後の車両位置および車両角度を予測する。現車速を維持した場合の一定時間後の車両位置、車両角度および、現加減速度を維持した場合の一定時間後の車両位置、車両角度をそれぞれ算出し、その両者の一定時間後の車両位置、車両角度の差である車両状態偏差に応じて補正操舵力を決定する。
【００２９】
図８に、現車速を維持した場合と現加減速度を維持した場合の車両軌道を示す。これは、車両軌道を真上から見たものであり、現車速を維持した場合と現減速度を維持した場合の車両位置をそれぞれ（Ｘｃ，Ｙｃ）、（Ｘｒ，Ｙｒ）、車両角度をθｃ、θｒとする。ここで車両角度は、現時点での車両の前後方向をＹ軸としたとき、このＹ軸と一定時間後の車両の前後方向Ｄとがなす角のことである。なお、現加速度を維持した場合も、現減速度を維持した場合と同様に以下の算出方法が適用される。
【００３０】
基本補正操舵力ΔＦ’は、両者の車両位置および車両角度の差を基本補正操舵力値に変換する一定の係数Ｋｅと、車両位置および車両角度の差をまとめて表すパラメータである走行状態偏差Ｅｃとから、以下のように表すことができる。
【数４】
基本補正操舵力ΔＦ'=Ｋｅ×走行状態偏差Ｅｃ（式４）
ここで，
【数５】

【００３１】
図９に、一定時間後の車両位置（Ｘｃ、Ｙｃ）、（Ｘｒ、Ｙｒ）および車両角度θｃ、θｒの算出方法の概要を示す。車両はステアリング操舵角に対応した円周に沿って旋回しているものとする。ここでは、微少時間Δｔ時間後の車両位置および車両角度の計算であり、一定時間Ｔｃ後の各値はこれをＴｃ／Δｔ回繰り返すものとする。この算出方法は、現車速を維持した場合と現加減速度を維持した場合とも共通である。
【００３２】
まず、操舵角度θｓおよびその微分値つまり操舵角速度θｓｄから、Δｔ秒後の操舵角度の予測値θｓ’を求める。
【数６】
操舵角度の予測値θｓ'＝θｓ（ｔ）＋Δｔ・θｓｄ（ｔ） (式６)
【００３３】
なお、計算開始時点の車両位置は（０，０）とし、車両の前後方向はＹ軸とする。操舵角度に対する車両角度の応答を係数Ｋで表すものとし、その計算時点における車速に対する舵角比をＧ（ｔ）とすると、車両進行方向（車両の前後方向Ｄ）に対する車両角度θは、以下で表すことができる。
【数７】
車両角度θ＝θｓ'・Ｇ（ｔ）・Ｋ (式７)
【００３４】
車速をＶ（ｔ）とするとΔｔ秒後の車両位置（ＸΔｔ、ＹΔｔ）は（式８）と表すことができる。
【数８】

【００３５】
また、Δｔ秒後の車両角度θΔｔは２θとなる。
【００３６】
これらの計算をＴｃ／Δｔ回繰り返し、一定時間Ｔｃ後の車両位置および車両角度を導出する。それを現車速を維持した場合と現加減速度を維持した場合の両方について求め、（式４）および（式５）により基本補正操舵力ΔＦ'および走行状態偏差Ｅｃを求める。
【００３７】
また、第２の実施の形態による車両用操舵装置は、第１の実施の形態と同様に、加速時は膨らみ、減速時は巻き込みに対する修正操作を補正するものであり、運転者が修正操作以外のステアリング操作を行っている場合は、補正を行わないようにする。具体的には、加速時は現車速を維持した場合の車両位置より、現加速度を維持した場合の車両位置が外側（カーブ旋回で膨らむ方向）である場合、減速時は現車速を維持した場合の車両位置より、現減速度を維持した場合の車両位置が内側（カーブ旋回で巻き込む方向）である場合に限り、操舵力補正を行う。また、その場合でも、走行状態偏差Ｅｃが一定または減少傾向にある場合のみ操舵力補正を行う。このような第２の実施の形態による車両用操舵装置における、車両軌道、走行状態偏差Ｅｃおよび操舵力補正の有無を図１０に示す。
【００３８】
以上説明したように、第２の実施の形態によると、第１の実施の形態と同様の効果が得られる。さらに、現車速を維持した場合の一定時間後の車両位置と車両角度および現加減速度を維持した場合の車両位置と車両角度から走行状態偏差Ｅｃを求め、この値に基づいて基本補正操舵力を決定するようにしたので、より詳細に車両状態を予測でき、予測される車両状態に応じて操舵力補正を行うことができる。また、加速旋回時は、車両軌道が現車速を維持した場合より膨らみ、さらに走行状態偏差Ｅｃが減少傾向または一定の場合、減速旋回時は、車両軌道が現車速を維持した場合より巻き込み、さらに走行状態偏差Ｅｃが減少傾向または一定の場合にそれぞれ操舵力補正を行うようにしたので、修正操舵を行うときに操舵力補正を行うことができる。
【００３９】
本発明は、現在の車両状態から一定時間後の車両状態を算出するとともに、算出された車両状態に基づいて操舵力を算出して操舵力補正を行う全ての車両用操舵装置に適用されるものである。そのため、操舵力の算出方法は、上記発明の実施の形態に限定されるものではない。
【図面の簡単な説明】
【図１】本発明による車両用操舵装置の一実施の形態の構成図
【図２】車速Ｖと舵角比Ｇの関係を示す図
【図３】車速Ｖと舵角比の変化量Ｇ’の関係を示す図
【図４】舵角比予測変化量ΔＧと基本補正操舵力ΔＦ’の関係を示す図
【図５】操舵角速度の絶対値｜θｓｄ｜と操舵力補正量の係数Ｋｆの関係を示す図
【図６】第１の実施の形態で操舵力補正を行う条件を示す図
【図７】制御装置５で実行される操舵力補正の手順を示すフローチャート
【図８】現車速を維持した場合と現加減速度を維持した場合の車両位置および車両角度を示す図
【図９】車両位置及び車両角度の算出方法の概要を示す図
【図１０】第２の実施の形態での操舵力補正を行う条件を示す図
【符号の説明】
１：ステアリングホイール
２：ラックアンドピニオン機構
３：舵角比可変装置
４：操舵力調節装置
５：制御装置
６：操舵角度検出装置
７：車速検出センサ
８：イグニションスイッチ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle steering apparatus in which a steering angle ratio changes in accordance with a vehicle speed, and more particularly to a vehicle steering apparatus that corrects a steering force for swelling and entrainment of a vehicle track during acceleration / deceleration.
[0002]
[Prior art]
Japanese Patent Application Laid-Open No. 11-334627 discloses a vehicle steering device that changes the steering angle ratio (front wheel steering angle / steering steering angle) according to the vehicle state. The steering angle ratio by the vehicle steering device changes with respect to the vehicle speed, the steering angle ratio is large at low vehicle speeds, and gradually decreases as the vehicle speed increases. Since the rudder angle ratio changes according to the vehicle speed, a vehicle that accelerates or decelerates at a constant steering angle has the characteristic that it bulges outward during an acceleration turn with respect to a vehicle with a fixed rudder angle ratio and entrains inward during a deceleration turn. Have. In such a conventional vehicle steering apparatus, the steering angle ratio is corrected according to the acceleration / deceleration.
[0003]
[Problems to be solved by the invention]
However, in the conventional device, the steering angle ratio is changed at the time of acceleration / deceleration. Therefore, compared with a vehicle having a constant steering angle ratio, the response of the vehicle to the steering angle changes, so the driver may feel uncomfortable. In addition, when the vehicle speed returns from acceleration to deceleration to a constant vehicle speed, the changed steering angle ratio becomes constant, so that the driver may similarly feel uncomfortable.
[0004]
According to the present invention, the driver naturally performs correction steering for the swelling of the vehicle track at the time of acceleration and the entrainment of the vehicle track at the time of deceleration while maintaining the characteristic that the steering angle ratio changes according to the vehicle speed even during acceleration / deceleration turning. An object of the present invention is to provide a vehicular steering apparatus.
[0005]
[Means for Solving the Problems]
An embodiment of a vehicle steering apparatus according to the present invention is shown in FIG.
(1) A steering apparatus for a vehicle according to a first aspect of the present invention includes a steering angle ratio variable device 3 that changes a steering angle ratio, which is a transmission ratio of a steering angle of a front wheel from a steering angle of the steering wheel 1, according to the vehicle speed, and a steering wheel. A steering force adjustment device 5 that adjusts a steering force that returns the steering wheel 1 to a neutral direction when the steering wheel 1 is steered; a vehicle state prediction device 5 that calculates a vehicle state after a predetermined time from the current vehicle state; A steering force calculation device 5 that calculates a steering force based on the calculated vehicle state, a control device 5 that corrects the steering force by controlling the steering force adjustment device 4 so as to obtain the calculated steering force, and a vehicle speed detection A vehicle speed detection device 7 that calculates the acceleration / deceleration of the current vehicle speed based on the detected vehicle speed, calculates the vehicle speed after a certain time from the acceleration / deceleration, and is detected. Present The steering angle ratio difference ΔG up to the vehicle speed after a certain time calculated from the vehicle speed of the vehicle is calculated, and the steering force calculation device 5 calculates a corrected steering force from the difference ΔG of the steering angle ratio, and sets a predetermined reference steering force. Is achieved with this corrected steering force to achieve the above-described object.
(2) According to the invention of claim 2, in the vehicle steering device of claim 1, the steering angle ratio decreases as the vehicle speed increases, and the control device 5 has a small steering force during acceleration and a large steering force during deceleration. Thus, the steering force adjustment device 4 is controlled so as to correct the steering force.
(3) The invention according to claim 3 is the vehicle steering apparatus according to claim 2, further comprising a steering angle detection device 6 for detecting the steering angle of the steering wheel 1, and the control device 5 is based on the detected steering angle. Thus, when the steering wheel 1 is steered at a constant steering angle or when the steering wheel 1 is turned up and operated, the steering wheel 1 is steered at a constant steering angle or when the steering wheel 1 is turned back down. In this case, the steering force is corrected respectively.
(4) According to a fourth aspect of the present invention, in the vehicle steering apparatus of the second aspect, the correction amount of the steering force that changes in accordance with the difference ΔG in the steering angle ratio is larger during deceleration than during acceleration. Features.
(5) The invention according to claim 5 is the vehicle steering apparatus according to claim 1, further comprising a steering angle detection device 6 for detecting the steering angle of the steering wheel 1, and the control device 5 determines the detected steering steering angle. A steering angular velocity is calculated on the basis of this, and steering force correction is performed when it is determined that the calculated steering steering angular velocity is equal to or less than a certain value.
(6) A vehicle steering apparatus according to a sixth aspect of the present invention includes a steering angle ratio variable device 3 that changes a steering angle ratio, which is a transmission ratio of a front wheel steering angle from a steering angle of the steering wheel 1, according to the vehicle speed, and a steering wheel. A steering force adjustment device 5 that adjusts a steering force that returns the steering wheel 1 to a neutral direction when the steering wheel 1 is steered; a vehicle state prediction device 5 that calculates a vehicle state after a predetermined time from the current vehicle state; A steering force calculation device 5 that calculates a steering force based on the calculated vehicle state, a control device 5 that corrects the steering force by controlling the steering force adjustment device 4 so as to obtain the calculated steering force, and a vehicle speed detection A vehicle speed detection device 7 and a steering angle detection device 6 for detecting the steering angle of the steering wheel 1, and the vehicle state prediction device 5 detects the steering angle ratio, the detected vehicle speed, the acceleration / deceleration calculated from the vehicle speed, and the detection. Vehicle position and vehicle angle after a certain time when the current vehicle speed is maintained, and vehicle after a certain time when the current acceleration / deceleration is maintained based on the steering steering angle and the steering steering angular velocity calculated from the steering angle. The vehicle state deviation, which is the difference between the position and the vehicle angle, is calculated, and the control device 5 calculates a correction steering force according to the calculated vehicle state deviation, and corrects a predetermined reference correction steering force with this correction steering force. This achieves the above-described object.
(7) The invention according to claim 7 is the vehicle steering apparatus according to claim 6, wherein the steering angle ratio decreases as the vehicle speed increases, and the control apparatus 5 has a small steering force during acceleration and a steering force during deceleration. The steering force is corrected by controlling the steering force adjusting device 4 so as to increase.
(8) The invention according to claim 8 is the vehicle steering apparatus according to claim 6, wherein the control device 5 has a vehicle position when the current acceleration is maintained rather than a vehicle position when the current vehicle speed is maintained during acceleration. there the outer case is (curve turning direction bulging in), and there at the time of deceleration than the vehicle position in the case of maintaining the current vehicle speed, (toward involving a curve turning) the vehicle position in the case of maintaining the current deceleration inner In this case, the steering force correction is performed respectively.
(9) The invention of claim 9 is characterized in that, in the vehicle steering device of claim 6, the control device 5 performs steering force correction when the vehicle state deviation tends to be constant or decreasing.
(10) The invention according to claim 10 is characterized in that, in the vehicle steering device according to claim 6, the control device 5 performs the steering force correction when the steering steering angular velocity is equal to or less than a predetermined value.
[0006]
In addition, in the section of the means for solving the above-described problems for explaining the configuration of the present invention, the drawings of the embodiments are used to explain the present invention in an easy-to-understand manner. It is not limited.
[0007]
【The invention's effect】
According to the present invention, in the vehicle steering apparatus in which the steering angle ratio changes depending on the vehicle speed, the steering force is calculated based on the current vehicle state and the vehicle state after a certain time, and the steering force correction is performed. The driver can naturally perform correction steering with respect to swelling and entrainment of the vehicle track during acceleration / deceleration.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
<< First Embodiment >>
A first embodiment of a vehicle steering system according to the present invention is shown in FIG. The vehicle steering apparatus includes a steering wheel 1, a steering angle ratio variable device 3 and a steering force adjustment device 4 provided between the steering wheel 1 and the rack and pinion mechanism 2, and a steering angle ratio variable device 3. And a control device 5 for changing and controlling the steering force by the steering angle ratio and steering force adjusting device 4. In accordance with the command amount from the control device 5, the steering angle ratio variable device 3 can arbitrarily set the steering angle ratio, and the steering force adjusting device 4 can arbitrarily adjust the steering force. Here, the steering force adjusting device 4 artificially generates self-aligning torque with an electric motor or the like, and adjusts the force in the direction to return the steering wheel 1 to the neutral state when the vehicle turns, that is, the steering force. it can. The control device 5 includes the steering angle of the steering wheel 1 detected by the steering angle detection device 6, the vehicle speed detected by the vehicle speed detection sensor 7, and the on / off state of the ignition key detected by the ignition switch 8. Entered.
[0009]
FIG. 2 shows the characteristic of the steering angle ratio with respect to the vehicle speed. The steering angle ratio is constant at the maximum value Gmax when the vehicle speed is VL or less, and gradually decreases when the vehicle speed is VL or more. For this reason, when acceleration / deceleration is performed with a constant steering angle, the vehicle has a characteristic that it bulges outward during an acceleration turn with respect to an ordinary vehicle having a fixed steering angle ratio, and winds inward during a deceleration turn.
[0010]
The vehicle steering apparatus according to the present invention assists in correction steering for swelling during acceleration turning and entrainment during deceleration turning, and changes the steering force in accordance with acceleration / deceleration. In the embodiment of the present invention, the steering force correction is not performed except during acceleration / deceleration.
[0011]
The steering wheel is reduced during acceleration turning, and the steering wheel 1 can be operated lightly when the driver performs a turning operation. The steering wheel is increased during deceleration turning, and the steering wheel is operated when the driver performs a switching back operation. 1 can be operated lightly. The steering force is calculated on the basis of the difference between the current vehicle state after a certain time and the steering angle ratio, for example (steering force calculation device). Hereinafter, the calculation method will be described.
[0012]
A steering angle ratio ahead of a predetermined time when the current acceleration / deceleration is maintained is predicted (vehicle state prediction device), and the steering force is increased or decreased according to the difference between the predicted steering angle ratio and the current steering angle ratio. The reason for taking the rudder angle ratio difference until a certain time is because the driver's reaction may be delayed in the method of correcting the steering force according to the change gradient of the current rudder angle ratio with respect to acceleration / deceleration. In the embodiment of the present invention, the correction amount of the steering force is determined by predicting a certain time ahead in consideration of the delay in the operation of the driver.
[0013]
As shown in FIG. 2, when the current vehicle speed is V0 and the vehicle speed after time Tc when the deceleration is maintained is V1, the steering angle ratio increases from G0 to G1. Here, the vehicle speed V1 is calculated by the following equation using the acceleration / deceleration V0d calculated from the time-series data of the vehicle speed V0.
[Expression 1]
V1 = V0 + Tc · V0d (Formula 1)
[0014]
FIG. 3 shows the change amount G ′ of the steering angle ratio with respect to the vehicle speed V. This is a derivative of the characteristic of the steering angle ratio G with respect to the vehicle speed V in FIG. In FIG. 3, the area (integrated value) from the vehicle speed V0 to the vehicle speed V1 is the difference in the steering angle ratio from the present time to the time Tc. If the unit time amount of this area is ΔG (hereinafter referred to as a steering angle ratio predicted change amount), it can be expressed as follows.
[Expression 2]

The sign is-when decelerating and + when accelerating.
[0015]
The steering force F is a predetermined correction value for the steering force derived below, which is a predetermined force F ′ (hereinafter referred to as a reference steering force) necessary to keep the steering angle of the steering wheel constant when traveling at a constant speed. It is assumed that ΔF ′ (hereinafter referred to as a basic correction steering force) is added.
[0016]
FIG. 4 shows the relationship between the steering angle ratio predicted change amount ΔG and the basic correction steering force ΔF ′. When the predicted change amount ΔG of the steering angle ratio is around 0 (−Gs ≦ ΔG ≦ Gs), the basic correction steering force ΔF ′ is set to zero so as not to react to slight acceleration / deceleration such as engine braking. That is, a dead zone is provided. When G <−Gs and Gs <G, the steering angle ratio predicted change amount ΔG and the basic correction steering force ΔF ′ are in a proportional relationship. However, this proportional gradient is changed during acceleration (steering angle ratio predicted change ΔG is +) and deceleration (steering angle ratio predicted change ΔG is −). This is because the driving operation is more difficult for the return operation during the deceleration turn than the increase operation during the acceleration turn, and this proportional gradient is increased so that a large steering force can be obtained during the deceleration turn. .
[0017]
Further, the correction steering operation for the swelling at the time of acceleration turning and the entrainment at the time of deceleration turning is a relatively slow operation as the operation of the steering wheel 1, and the operation of the steering wheel 1 faster than that is a constant turning trajectory of the vehicle. Therefore, it is assumed that the steering wheel 1 is operated when the vehicle is not traveling, and the steering force is not corrected. Here, the steering angular velocity θsd is used as a value representing the operation speed of the steering wheel.
[0018]
FIG. 5 shows a relationship between the absolute value | θsd | of the steering angular velocity and the coefficient Kf of the steering force correction amount. The coefficient Kf of the steering force correction amount is a coefficient to be applied to the basic correction steering force ΔF ′. When the absolute value of steering angular velocity | θsd | is equal to or greater than a certain value, the coefficient Kf of the basic steering force correction amount is set to zero and the steering force correction is not performed. From the above, the steering force is expressed by the following equation.
[Equation 3]
Steering force F = reference steering force F ′ + corrected steering force ΔF ′ × Kf (Formula 3)
[0019]
Here, the vehicle steering apparatus according to the present invention assists in a correction operation for a phenomenon that swells at the time of acceleration and gets involved at the time of deceleration, and does not perform correction in other operations. FIG. 6 shows a case where the steering force correction is performed and a case where the steering force correction is not performed. The steering force is corrected only when the steering angle is constant or increased during acceleration turning, and only when the steering angle is constant or switching back during deceleration turning.
[0020]
The processing procedure of the control device 5 for performing the steering force correction by the method described above is shown in the flowchart of FIG.
[0021]
The vehicle speed V0 and the steering angle θs are read (step S1). Based on the time-series data of these values and FIG. 6, it is determined whether or not the steering force correction is to be performed (step S2). If a positive determination is made in step S3 that the steering force is corrected, the current acceleration / deceleration V0d is obtained from the time-series data of the vehicle speed V (step S4), and the vehicle speed V1 after a certain time Tc is calculated by (Equation 1). (Step S5).
[0022]
In step S6, a steering angle ratio predicted change amount ΔG is obtained from the steering angle change amount G ′ of FIG. 3 and (Equation 2). From this ΔG and FIG. 4, a basic correction steering force ΔF ′ is calculated (step S7). Next, the coefficient Kf is obtained from the absolute value | θsd | of the steering angular velocity from FIG. 5 (step S8). The steering force F is derived from the reference steering force F ′, the basic correction steering force ΔF ′, and the coefficient Kf by (Equation 3) (step S9). In step S10, the steering force adjusting device 4 is driven so that the steering force F is obtained.
[0023]
If it is determined in step S3 that the steering force correction is not performed, the steering force F is set to the reference steering force F ′ (step S12), and the steering force adjusting device 4 is driven so that the steering force F is obtained in step S10. To do.
[0024]
If it is determined affirmative in step S11 that the key is OFF, the control is terminated. If a negative determination is made, the process returns to step S1 again to continue the control.
[0025]
As described above, in the vehicle steering apparatus according to the first embodiment, the basic correction is performed according to the steering angle ratio predicted change amount ΔG that is the difference between the current steering angle ratio and the predicted steering angle ratio ahead of a certain time. The steering force is determined, and the steering force adjustment device 4 is driven so as to obtain a steering force calculated by adding / subtracting the basic correction steering force to / from the reference steering force to correct the steering force. Therefore, the driver can naturally perform the correction steering for the swelling at the time of acceleration and the entrainment at the time of deceleration without changing the steering angle ratio at the time of acceleration / deceleration turning. In addition, in the relationship between the steering angle ratio predicted change amount ΔG and the basic correction steering force shown in FIG. 4, the proportional gradient is increased at the time of decelerating turning, which is difficult to drive compared to at the time of acceleration turning. Power is obtained. In addition, when the steering operation is slow, it is determined that the driver is performing the correction steering of the vehicle track, so that the steering force correction can be performed when the correction steering is being performed. Furthermore, since the steering force correction is performed only when the steering angle is constant or increased during acceleration turning, and only when the steering angle is constant or switching back during deceleration turning, the steering force correction can be performed when performing correction steering. .
[0026]
<< Second Embodiment >>
In the vehicle steering apparatus according to the first embodiment, the basic correction steering force ΔF ′ is determined based on the steering angle ratio difference ΔG during acceleration / deceleration. However, the vehicle steering apparatus according to the second embodiment is more detailed. The basic correction steering force ΔF ′ is obtained by predicting the vehicle state.
[0027]
The configuration of the vehicle steering device according to the second embodiment is the same as that of the first embodiment shown in FIG. 1, but the processing content in the control device 5 is different from that of the first embodiment. Hereinafter, differences from the first embodiment will be mainly described.
[0028]
A vehicle position and a vehicle angle after a predetermined time are predicted from the steering angle ratio, the vehicle speed, the acceleration / deceleration, the steering steering angle, and the steering steering angular velocity. Calculate the vehicle position and vehicle angle after a certain time when maintaining the current vehicle speed, the vehicle position and vehicle angle after a certain time when maintaining the current acceleration / deceleration, respectively, A corrected steering force is determined according to a vehicle state deviation that is a difference in vehicle angle.
[0029]
FIG. 8 shows vehicle tracks when the current vehicle speed is maintained and when the current acceleration / deceleration is maintained. This is a view of the vehicle trajectory from directly above. The vehicle positions when the current vehicle speed is maintained and when the current deceleration is maintained are (Xc, Yc) and (Xr, Yr), respectively, and the vehicle angle is θc. , Θr. Here, the vehicle angle is an angle formed by the Y-axis and the vehicle front-rear direction D after a certain period of time when the vehicle front-rear direction is the Y-axis. Even when the current acceleration is maintained, the following calculation method is applied in the same manner as when the current deceleration is maintained.
[0030]
The basic correction steering force ΔF ′ is a constant coefficient Ke for converting the difference between the vehicle position and the vehicle angle into a basic correction steering force value, and a running state deviation Ec that collectively represents the difference between the vehicle position and the vehicle angle. From the above, it can be expressed as follows.
[Expression 4]
Basic correction steering force ΔF ′ = Ke × running state deviation Ec (Formula 4)
here,
[Equation 5]

[0031]
FIG. 9 shows an outline of a method for calculating the vehicle positions (Xc, Yc), (Xr, Yr) and the vehicle angles θc, θr after a certain time. It is assumed that the vehicle is turning along a circumference corresponding to the steering angle. Here, it is the calculation of the vehicle position and the vehicle angle after a minute time Δt, and each value after a certain time Tc is repeated Tc / Δt times. This calculation method is common to both the case where the current vehicle speed is maintained and the case where the current acceleration / deceleration is maintained.
[0032]
First, a predicted value θs ′ of the steering angle after Δt seconds is obtained from the steering angle θs and its differential value, that is, the steering angular velocity θsd.
[Formula 6]
Steering angle predicted value θs ′ = θs (t) + Δt · θsd (t) (Formula 6)
[0033]
Note that the vehicle position at the start of calculation is (0, 0), and the longitudinal direction of the vehicle is the Y axis. Assuming that the response of the vehicle angle to the steering angle is represented by a coefficient K, and the steering angle ratio to the vehicle speed at the time of calculation is G (t), the vehicle angle θ with respect to the vehicle traveling direction (vehicle longitudinal direction D) is Can be represented.
[Expression 7]
Vehicle angle θ = θs ′ · G (t) · K (Expression 7)
[0034]
If the vehicle speed is V (t), the vehicle position (XΔt, YΔt) after Δt seconds can be expressed as (Equation 8).
[Equation 8]

[0035]
Further, the vehicle angle θΔt after Δt seconds is 2θ.
[0036]
These calculations are repeated Tc / Δt times to derive the vehicle position and vehicle angle after a certain time Tc. It is obtained for both the case where the current vehicle speed is maintained and the case where the current acceleration / deceleration is maintained, and the basic correction steering force ΔF ′ and the running state deviation Ec are obtained from (Equation 4) and (Equation 5).
[0037]
Further, the vehicle steering apparatus according to the second embodiment, like the first embodiment, swells when accelerating and corrects the correction operation for the entrainment when decelerating. When the steering operation is performed, correction is not performed. Specifically, when the vehicle position when the current acceleration is maintained is outside (the direction in which the vehicle turns when turning), compared to the vehicle position when the current vehicle speed is maintained during acceleration, or when the current vehicle speed is maintained during deceleration The steering force correction is performed only when the vehicle position when the current deceleration is maintained is the inner side (the direction in which the vehicle is involved in the curve turning). Even in this case, the steering force correction is performed only when the running state deviation Ec is constant or decreasing. FIG. 10 shows the vehicle track, the running state deviation Ec, and the presence or absence of steering force correction in the vehicle steering apparatus according to the second embodiment.
[0038]
As described above, according to the second embodiment, the same effect as in the first embodiment can be obtained. Further, a running state deviation Ec is obtained from the vehicle position and vehicle angle after a certain time when the current vehicle speed is maintained and the vehicle position and vehicle angle when the current acceleration / deceleration is maintained, and the basic correction steering force is calculated based on this value. Since it is determined, the vehicle state can be predicted in more detail, and the steering force correction can be performed according to the predicted vehicle state. Further, when the vehicle turns, the vehicle track swells more than when the current vehicle speed is maintained, and when the running state deviation Ec is decreasing or constant, when the vehicle is decelerated, the vehicle track is involved more than when the current vehicle speed is maintained. Since the steering force correction is performed when the traveling state deviation Ec is decreasing or constant, the steering force correction can be performed when the correction steering is performed.
[0039]
The present invention is applied to all vehicle steering devices that calculate a vehicle state after a predetermined time from the current vehicle state and calculate a steering force based on the calculated vehicle state to correct a steering force. It is. Therefore, the method for calculating the steering force is not limited to the above-described embodiment.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of a vehicle steering apparatus according to the present invention. FIG. 2 is a diagram showing a relationship between a vehicle speed V and a steering angle ratio G. FIG. FIG. 4 is a diagram showing a relationship between a steering angle ratio predicted change amount ΔG and a basic correction steering force ΔF ′. FIG. 5 is a graph showing a relationship between an absolute value of steering angular velocity | θsd | and a coefficient Kf of a steering force correction amount. FIG. 6 is a diagram showing conditions for performing steering force correction in the first embodiment. FIG. 7 is a flowchart showing a steering force correction procedure executed by the control device 5. FIG. 8 is to maintain the current vehicle speed. FIG. 9 is a diagram showing an outline of a method for calculating the vehicle position and the vehicle angle when the vehicle is operated and the current acceleration / deceleration is maintained. FIG. 10 is a diagram showing the outline of a calculation method of the vehicle position and the vehicle angle. Diagram showing conditions for correction 【Explanation of symbols】
1: Steering wheel 2: Rack and pinion mechanism 3: Steering angle ratio varying device 4: Steering force adjusting device 5: Control device 6: Steering angle detecting device 7: Vehicle speed detecting sensor 8: Ignition switch

Claims

A steering angle ratio variable device that changes a steering angle ratio, which is a transmission ratio of the steering angle of the steering wheel to the front wheel steering angle, according to the vehicle speed;
A steering force adjusting device for adjusting a steering force for returning the steering wheel to a neutral direction when the steering wheel is steered;
A vehicle state prediction device for calculating a vehicle state after a certain time from the current vehicle state;
A steering force calculation device that calculates the steering force based on the calculated vehicle state;
A control device for correcting the steering force by controlling the steering force adjusting device so as to obtain the calculated steering force ;
A vehicle speed detection device for detecting the vehicle speed,
The vehicle state prediction device calculates an acceleration / deceleration of the current vehicle speed based on the detected vehicle speed, calculates a vehicle speed after a predetermined time from the calculated acceleration / deceleration, and calculates the vehicle speed from the detected current vehicle speed. Calculate the difference ΔG in the steering angle ratio up to the calculated vehicle speed after a certain period of time,
The steering force computation unit, the calculated calculates a correction steering force from the difference ΔG steering ratio, the vehicle characterized that you correct the reference steering force predetermined by the calculated correction steering force Steering device.

The vehicle steering system according to claim 1, wherein
The rudder angle ratio decreases as the vehicle speed increases,
The vehicle steering device according to claim 1, wherein the control device performs steering force correction by controlling the steering force adjusting device so that the steering force is small during acceleration and the steering force is large during deceleration .

The vehicle steering apparatus according to claim 2, wherein
A steering angle detection device for detecting a steering angle of the steering wheel;
Based on the detected steering angle, the control device controls the steering wheel when the vehicle is decelerating when the steering angle of the steering wheel is constant or when the steering wheel is increased and operated. A steering apparatus for a vehicle, wherein the steering force is corrected when a steering angle is constant or when the steering wheel is turned back .

The vehicle steering apparatus according to claim 2 , wherein
The vehicle steering apparatus according to claim 1, wherein the amount of correction of the steering force that changes in accordance with the difference ΔG in the steering angle ratio is greater during deceleration than during acceleration .

The vehicle steering system according to claim 1 , wherein
A steering angle detection device for detecting a steering angle of the steering wheel;
The control device calculates a steering angular velocity based on the detected steering steering angle, and performs steering force correction when the calculated steering steering angular velocity is determined to be equal to or less than a predetermined value. apparatus.

A steering angle ratio variable device that changes a steering angle ratio, which is a transmission ratio of the steering angle of the steering wheel to the front wheel steering angle, according to the vehicle speed;
A steering force adjusting device for adjusting a steering force for returning the steering wheel to a neutral direction when the steering wheel is steered;
A vehicle state prediction device for calculating a vehicle state after a certain time from the current vehicle state;
A steering force calculation device that calculates the steering force based on the calculated vehicle state;
A control device for correcting the steering force by controlling the steering force adjusting device so as to obtain the calculated steering force;
A vehicle speed detection device for detecting the vehicle speed;
A steering angle detection device for detecting a steering angle of the steering wheel,
The vehicle state prediction device is configured to generate a current value based on the steering angle ratio, the detected vehicle speed, an acceleration / deceleration calculated from the vehicle speed, the detected steering steering angle, and a steering steering angular velocity calculated from the steering angle. The vehicle position and the vehicle angle after a certain time when the vehicle speed is maintained, and the vehicle position and the vehicle angle after a certain time when the current acceleration / deceleration is maintained, and the calculated vehicle after the certain time. Calculate the vehicle state deviation, which is the difference between the position and the vehicle angle,
The control device calculates a corrected steering force in accordance with the calculated vehicle state deviation, and corrects a predetermined reference steering force with the calculated corrected steering force .

The vehicle steering apparatus according to claim 6 , wherein
The rudder angle ratio decreases as the vehicle speed increases,
The vehicle steering device according to claim 1, wherein the control device performs steering force correction by controlling the steering force adjusting device so that the steering force is small during acceleration and the steering force is large during deceleration .

The vehicle steering apparatus according to claim 6 , wherein
The control device is effective when the vehicle position when the current acceleration is maintained is outside (in a direction in which the vehicle turns in a curve) from the vehicle position when the current vehicle speed is maintained during acceleration and when the vehicle is decelerated. A steering apparatus for a vehicle, which performs steering force correction when the vehicle position when the current deceleration is maintained is inward (in the direction of winding in a curve turn) from the vehicle position when the vehicle speed is maintained .

The vehicle steering apparatus according to claim 6 , wherein
The control device performs a steering force correction when the vehicle state deviation is constant or tends to decrease .

The vehicle steering apparatus according to claim 6 , wherein
The vehicle steering device according to claim 1, wherein the control device performs steering force correction when the steering angular velocity is equal to or less than a predetermined value .