JP2619658B2 - Control method of four-wheel steering device for automobile - Google Patents
Control method of four-wheel steering device for automobileInfo
- Publication number
- JP2619658B2 JP2619658B2 JP62269909A JP26990987A JP2619658B2 JP 2619658 B2 JP2619658 B2 JP 2619658B2 JP 62269909 A JP62269909 A JP 62269909A JP 26990987 A JP26990987 A JP 26990987A JP 2619658 B2 JP2619658 B2 JP 2619658B2
- Authority
- JP
- Japan
- Prior art keywords
- wheel steering
- steering angle
- front wheel
- rear wheel
- road
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D7/00—Steering linkage; Stub axles or their mountings
- B62D7/06—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins
- B62D7/14—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering
- B62D7/15—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels
- B62D7/159—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Theoretical Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Steering-Linkage Mechanisms And Four-Wheel Steering (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は自動車用４輪操舵装置の制御方法に関するも
のである。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a four-wheel steering device for an automobile.
従来の技術 自動車において、前輪の操舵に応じて後輪を転舵させ
るようにした４輪操舵装置は従来より種々開発され、例
えば特開昭61−57466号公報にて公開されている。2. Description of the Related Art In a motor vehicle, various four-wheel steering devices in which the rear wheels are steered according to the steering of the front wheels have been conventionally developed, and are disclosed, for example, in Japanese Patent Application Laid-Open No. 61-57466.
上記のような４輪操舵装置は、従来は一般にハンドル
操作角等により検出した前輪舵角と車速センサにて検出
した車速とから後輪操舵角（転舵方向を含む）目標値を
決定し、後輪操舵用アクチュエータ（油圧アクチュエー
タ或は電動モータ等）を作動させて上記目標値通りに後
輪を転舵させるようになっており、例えば低車速域では
後輪を前輪とは逆方向に転舵させて旋回性の向上をはか
り、中，高車速域では後輪を前輪と同方向に転舵させて
安定性の向上をはかると言う制御を行っているのが普通
である。Conventionally, such a four-wheel steering device generally determines a rear wheel steering angle (including a steering direction) target value from a front wheel steering angle detected by a steering wheel operation angle or the like and a vehicle speed detected by a vehicle speed sensor. The rear wheel steering actuator (hydraulic actuator or electric motor, etc.) is operated to steer the rear wheel according to the target value. For example, in a low vehicle speed range, the rear wheel rotates in the opposite direction to the front wheel. In general, control is performed to steer the steering wheel so as to improve turning performance, and to steer the rear wheel in the same direction as the front wheel in the middle and high vehicle speed ranges to improve the stability.
発明が解決しようとする問題点 上記のような前後輪操舵装置は、車速に応じて変化す
る前後輪舵角比の特性を予じめコントロールユニットに
設定しておき、前輪舵角情報と車速情報とからコントロ
ールユニットが上記設定特性に基づき後輪操舵角目標値
を決定し、この目標値通りに後輪を転舵させると言う制
御を行うものである。Problems to be Solved by the Invention In the front and rear wheel steering apparatus as described above, the characteristic of the front and rear wheel steering angle ratio that changes according to the vehicle speed is set in advance in the control unit, and the front wheel steering angle information and the vehicle speed information are set. Thus, the control unit determines the rear wheel steering angle target value based on the set characteristics, and performs control to turn the rear wheels according to the target value.
しかし車両の運動性能は路面状態によって大きく影響
され、特に荒れた路面（例えば砂利路等）ではドライバ
の予期しない挙動を示すことがあり安定性が悪くなる。However, the kinetic performance of the vehicle is greatly affected by the road surface condition, and particularly on a rough road surface (for example, a gravel road), the behavior of the driver may be unexpected and the stability is deteriorated.
本発明は上記の点に対処することを主目的とするもの
である。The present invention has as its main object to address the above points.
問題点を解決するための手段 本発明は、上記のような４輪操舵装置において、前輪
の舵角を検出する前輪舵角センサの前輪舵角信号の変動
周波数が所定値より大きい変動周波数における変動成分
の振幅の平方和が所定時間内に設定値以上となった場合
悪路と判断し、後輪の同相方向の操舵量を増大させる制
御を行うことを特徴とするものである。Means for Solving the Problems The present invention relates to a four-wheel steering system as described above, wherein the fluctuation frequency of the front wheel steering angle signal of the front wheel steering angle sensor for detecting the steering angle of the front wheel is higher than the predetermined value. When the sum of squares of the component amplitudes is equal to or greater than a set value within a predetermined time, it is determined that the road is bad, and control is performed to increase the amount of steering of the rear wheels in the same phase.
作用 上記により、例えば砂利路等の荒れた路面を走行する
ときはコントロールユニットが前輪舵角信号の変動から
路面の荒さを的確に推定し、標準的な前後輪転舵比特性
で後輪を転舵させる場合より同相方向に後輪操舵量を増
大させることによって、車両挙動の変化を少くし、操縦
安定性の向上をはかることができる。Effect As described above, when traveling on rough roads such as gravel roads, the control unit accurately estimates the road surface roughness from fluctuations in the front wheel steering angle signal, and steers the rear wheels with the standard front and rear wheel steering ratio characteristics. By increasing the amount of rear wheel steering in the same phase direction as in the case where the vehicle is driven, a change in vehicle behavior can be reduced, and steering stability can be improved.
又、４輪操舵車両において通常装備されている前輪舵
角センサの前輪舵角信号を用いて路面状態を判断する構
成を採っているので、例えば車体の上下動を検出するセ
ンサ等の新規な路面状態検出手段の追加なしに、精度の
よい路面状態の検出が可能となり、構成の簡略化及びコ
ストの低廉化をはかることができる。In addition, since the road surface condition is determined using the front wheel steering angle signal of the front wheel steering angle sensor normally equipped in a four-wheel steering vehicle, a new road surface such as a sensor for detecting the vertical movement of the vehicle body is used. The road surface condition can be detected with high accuracy without adding a state detecting means, and the configuration can be simplified and the cost can be reduced.
実施例 以下本発明の実施例を附図を参照して説明する。Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.
第１図において、１はハンドル、２は従来より公知の
例えばラックピニオン形式等の前輪操舵機構、３は前輪
であり、ハンドル１から前輪３に至る前輪操舵機構２に
は例えばステアリングシャフトの回転角，ラックシャフ
トの摺動変位量等から前輪３の舵角を検出する前輪舵角
センサ４が設けられ、該前輪舵角センサ４の前輪舵角信
号と車速センサ５の車速信号とはコントロールユニット
６にインプットされる。In FIG. 1, reference numeral 1 denotes a steering wheel, 2 denotes a conventionally known front wheel steering mechanism of, for example, a rack and pinion type, 3 denotes front wheels, and a front wheel steering mechanism 2 from the steering wheel 1 to the front wheels 3 includes, for example, a rotation angle of a steering shaft. A front wheel steering angle sensor 4 for detecting the steering angle of the front wheels 3 based on the amount of sliding displacement of the rack shaft is provided. The front wheel steering angle signal of the front wheel steering angle sensor 4 and the vehicle speed signal of the vehicle speed sensor 5 are controlled by a control unit 6. Is input to
コントロールユニット６には例えば第３図の点線にて
示すような車速に対応する前後輪転舵比の特性Ａが予じ
め設定されており、前輪舵角信号と車速信号がインプッ
トされると該設定特性Ａに基づき後輪操舵角目標値を決
定して出力信号を発するようになっている。For example, a characteristic A of the front and rear wheel steering ratio corresponding to the vehicle speed as shown by a dotted line in FIG. 3 is set in the control unit 6 in advance, and the setting is made when a front wheel steering angle signal and a vehicle speed signal are input. A rear wheel steering angle target value is determined based on the characteristic A, and an output signal is issued.
７はモータ、８は電磁クラッチであり、上記コントロ
ールユニット６の出力信号によって電磁クラッチ８がオ
ンとなると共にモータ７が回転し、ウオームギヤ，ウオ
ームホイール等の減速機構およびリンク機構等よりなる
後輪操舵機構９を介して後輪10が転舵され、後輪舵角を
検出する後輪舵角センサ11の後輪舵角信号及びモータの
回転速度を検出するモータ回転速度センサ12のモータ回
転速度信号等によるフィードバック制御により、後輪10
を上記コントロールユニット６が決定した後輪操舵角目
標値通りに転舵させるようになっている。Reference numeral 7 denotes a motor, and 8 denotes an electromagnetic clutch. The electromagnetic clutch 8 is turned on by the output signal of the control unit 6, and the motor 7 is rotated. The rear wheel steering is constituted by a reduction mechanism such as a worm gear and a worm wheel, and a link mechanism. A rear wheel 10 is steered through a mechanism 9, a rear wheel steering angle signal of a rear wheel steering angle sensor 11 for detecting a rear wheel steering angle, and a motor rotation speed signal of a motor rotation speed sensor 12 for detecting a rotation speed of a motor. The feedback control of the rear wheel 10
Is steered according to the rear wheel steering angle target value determined by the control unit 6.
コントロールユニット６には、第２図に示すように前
輪舵角センサ４の前輪舵角信号と車速センサ５の車速信
号とから後輪操舵角目標値を決定する後輪操舵角演算部
61が設けられると共に、上記前輪舵角信号から悪路かど
うかを判断する悪路判定部62が設けられている。The control unit 6 includes a rear wheel steering angle calculation unit that determines a rear wheel steering angle target value from the front wheel steering angle signal of the front wheel steering angle sensor 4 and the vehicle speed signal of the vehicle speed sensor 5 as shown in FIG.
61 is provided, and a rough road determination unit 62 for determining whether the road is a rough road from the front wheel steering angle signal is provided.
即ち、前輪舵角信号はローパスフィルタLPFにて平滑
処理されて後輪操舵角演算部61に入力され、前述したよ
うに例えば第３図点線示の特性Ａに基づき後輪操舵角目
標値を決定し、後輪を該目標値通りに転舵させると言う
制御を行う。That is, the front wheel steering angle signal is smoothed by the low-pass filter LPF and input to the rear wheel steering angle calculation unit 61, and as described above, the rear wheel steering angle target value is determined based on, for example, the characteristic A shown by the dotted line in FIG. Then, control for turning the rear wheels according to the target value is performed.
前輪舵角信号はハイパスフィルタHPFを介して悪路判
定部62にも入力され、第４図に示すような方法で走行路
面が悪路であるかどうかを判定し、悪路であると判断し
たときは後輪操舵角演算部61に信号を発して上記第３図
点線示の特性Ａを実線示Ｂの如く全車速範囲にわたり同
相方向にずらせた特性に変更させ、後輪操舵角演算部61
は実線示Ｂの特性に基づき後輪操舵角目標値を決定する
ことにより、良路の場合に比し、逆相転舵の場合は逆相
転舵量が小，同相転舵の場合は同相転舵量が大となると
言うように、いずれの場合も良路のときよりアンダステ
ア傾向を増加させるよう後輪操舵量が変更される。The front wheel steering angle signal is also input to the rough road determination unit 62 via the high-pass filter HPF, and it is determined whether the traveling road surface is a rough road by the method shown in FIG. At this time, a signal is sent to the rear wheel steering angle calculation unit 61 to change the characteristic A shown by the dotted line in FIG. 3 to a characteristic shifted in the same phase direction over the entire vehicle speed range as shown by the solid line B, and the rear wheel steering angle calculation unit 61
By determining the rear wheel steering angle target value based on the characteristics shown by the solid line B, the reverse phase steering amount is smaller in the case of reverse phase steering, and the same phase In any case, the steering amount of the rear wheel is changed so that the understeer tendency is increased as compared to the case of a good road.
荒れた路面では路面の影響を受けて、第５図に例示す
るように良路のコーナリング時に比し前輪舵角信号の変
動が細かくなる。On a rough road surface, the front wheel steering angle signal fluctuates more finely than when cornering on a good road, as illustrated in FIG. 5, due to the influence of the road surface.
そこで前輪舵角信号が入力されたとき、第４図のフロ
ーチャートに示すように、先ずハイパスフィルタHPFに
て前輪舵角信号の周波数ｆが所定値f0（例えばf0＝10Hz
程度に設定される）より大である変動周波数における変
動成分だけ取出し、次にｆ＞f0の変動成分の振幅の平方
和ａを求める。そして所定時間内（例えば0.2秒程度に
設定される）の振幅の平方和ａと設定値a0とを比較し、
ａ＞a0でった場合悪路であると判断し、前述したように
後輪操舵角演算部61に後輪操舵量変更指令を発し、良路
の場合よりアンダステア傾向を増加させる方向に後輪操
舵量を変更させることにより、荒れた路面での車両挙動
の変化を減少させ、操縦安定性の向上をはかることがで
きるものである。Therefore, when the front wheel steering angle signal is input, as shown in the flowchart of FIG. 4, first, the frequency f of the front wheel steering angle signal is increased by a high-pass filter HPF to a predetermined value f 0 (for example, f 0 = 10 Hz).
Then, only the fluctuation component at the fluctuation frequency which is larger than (set to about) is extracted, and then the sum of squares a of the amplitude of the fluctuation component of f> f 0 is obtained. Then, the sum of squares a of the amplitude within a predetermined time (for example, set to about 0.2 seconds) is compared with the set value a 0 ,
determining that bad road if De'a> a 0, emits the rear wheel steering amount change command to the rear wheel steering angle calculation section 61 as described above, after the direction of increasing the understeer tendency than in the case of good road By changing the wheel steering amount, a change in vehicle behavior on a rough road surface can be reduced, and steering stability can be improved.
尚上記実施例では前輪舵角と車速とから後輪操舵角目
標値を決定する例を示しているが、本発明は例えば前輪
の操舵トルク或はパワステアリング装置を装備したもの
の場合は該パワステアリング装置による操舵補助力等か
ら前輪舵力を検出し該前輪舵力と車速とから後輪操舵角
目標値を決定するようにした４輪操舵装置にも適用可能
であり、又後輪操舵用のアクチュエータおよび後輪操舵
機構等は図示のモータおよびリンク機構以外従来より公
知の任意のものを採用可能であることは言うまでもな
い。In the above embodiment, an example is shown in which the rear wheel steering angle target value is determined from the front wheel steering angle and the vehicle speed. The present invention is also applicable to a four-wheel steering system in which front wheel steering force is detected from a steering assist force by the device and a rear wheel steering angle target value is determined from the front wheel steering force and the vehicle speed. It goes without saying that any known actuators and rear wheel steering mechanisms other than the illustrated motor and link mechanism can be used.
発明の効果 以上のように本発明によれば、前輪舵角を検出する前
輪舵角センサの前輪舵角信号の変動から路面が悪路であ
るかどうかを的確に判断し、悪路であると判定したとき
は、良路のときに比し、後輪の操舵量を同相方向即ちア
ンダステア傾向を増加させる方向に変更させる制御を行
うことにより、悪路走行時の車両挙動の変化を減少さ
せ、操縦安定性の著しい向上をはかることができるもの
である。Advantageous Effects of the Invention As described above, according to the present invention, it is accurately determined whether or not a road surface is a rough road from a fluctuation of a front wheel steering angle signal of a front wheel rudder angle sensor that detects a front wheel steering angle. When it is determined, by performing control to change the steering amount of the rear wheels in the in-phase direction, that is, the direction to increase the understeer tendency, as compared with the case of a good road, a change in vehicle behavior during traveling on a rough road is reduced, The steering stability can be significantly improved.
更に、本発明では、４輪操舵車両において通常装備さ
れている前輪舵角センサの前輪舵角信号を用いて路面状
態の判断を行う構成を採っているので、路面状態判断の
ための新たな検出手段の追加は全く不要であり、構成の
簡略化及びコストの低廉化をはかることができるもの
で、実用上多大の効果をもたらし得るものである。Further, the present invention adopts a configuration in which the road surface state is determined using the front wheel steering angle signal of the front wheel steering angle sensor normally equipped in a four-wheel steering vehicle, so that a new detection for determining the road surface state is performed. No additional means is required at all, and the structure can be simplified and the cost can be reduced, and a great effect can be obtained in practical use.
第１図は本発明の一実施例を示す平面説明図、第２図は
コントロールユニット部における制御系統のブロック
図、第３図は前後輪転舵比特性の一例を示す図、第４図
は悪路判定方法の一例を示すフローチャート、第５図は
前輪舵角信号の良路と悪路との比較を示す図である。 １……ハンドル、２……前輪操舵機構、３……前輪、４
……前輪舵角センサ、５……車速センサ、６……コント
ロールユニット、７……モータ、９……後輪操舵機構、
10……後輪、11……後輪舵角センサ。1 is an explanatory plan view showing one embodiment of the present invention, FIG. 2 is a block diagram of a control system in a control unit, FIG. 3 is a diagram showing an example of front-rear wheel turning ratio characteristics, and FIG. FIG. 5 is a flowchart illustrating an example of a road determination method, and FIG. 5 is a diagram illustrating a comparison between a good road and a bad road of a front wheel steering angle signal. 1 ... steering wheel, 2 ... front wheel steering mechanism, 3 ... front wheel, 4
... front wheel steering angle sensor, 5 ... vehicle speed sensor, 6 ... control unit, 7 ... motor, 9 ... rear wheel steering mechanism,
10 ... rear wheel, 11 ... rear wheel steering angle sensor.
Claims (1)
を制御する自動車用４輪操舵装置において、前輪舵角を
検出する前輪舵角センサの前輪舵角信号の変動周波数が
所定値より大である変動周波数における変動成分の振幅
の所定時間内の平方和が設定値より大であったとき悪路
と判定し、後輪の同相方向の操舵量を増大させる制御を
行うことを特徴とする自動車用４輪操舵装置の制御方
法。In a four-wheel steering apparatus for an automobile for controlling a rear wheel steering angle from a front wheel steering angle or a steering force and a vehicle speed, a variable frequency of a front wheel steering angle signal of a front wheel steering angle sensor for detecting a front wheel steering angle is predetermined. When the sum of squares of the amplitude of the fluctuation component at the fluctuation frequency that is larger than the predetermined value is larger than the set value, it is determined that the road is a bad road, and the control to increase the in-phase steering amount of the rear wheels is performed. A method for controlling a four-wheel steering device for a vehicle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62269909A JP2619658B2 (en) | 1987-10-26 | 1987-10-26 | Control method of four-wheel steering device for automobile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62269909A JP2619658B2 (en) | 1987-10-26 | 1987-10-26 | Control method of four-wheel steering device for automobile |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01111573A JPH01111573A (en) | 1989-04-28 |
| JP2619658B2 true JP2619658B2 (en) | 1997-06-11 |
Family
ID=17478910
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62269909A Expired - Lifetime JP2619658B2 (en) | 1987-10-26 | 1987-10-26 | Control method of four-wheel steering device for automobile |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2619658B2 (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62131881A (en) * | 1985-12-04 | 1987-06-15 | Toyota Motor Corp | Rear wheel steering control device for front and rear wheel steering vehicle |
-
1987
- 1987-10-26 JP JP62269909A patent/JP2619658B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01111573A (en) | 1989-04-28 |
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