JP2005206115A

JP2005206115A - Steering device for vehicle

Info

Publication number: JP2005206115A
Application number: JP2004017181A
Authority: JP
Inventors: Masahiro Kubota; 正博久保田
Original assignee: Nissan Motor Co Ltd
Current assignee: Nissan Motor Co Ltd
Priority date: 2004-01-26
Filing date: 2004-01-26
Publication date: 2005-08-04

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device for a vehicle capable of transmitting difference of left and right road surfaces μ to a driver as difference of weight of steering. <P>SOLUTION: A controller 13 is provided with a road surface μ presumption means 26 for presuming the road surface μ of left and right rear wheels based on output of left and right rear wheel axle force sensors 20, 21 and a motor speed sensor 22. When difference of a predetermined value or higher exists on the road surfaces μ of the left and right wheels, steering auxiliary force in left steering and right steering is changed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、操舵量に応じて運転者の操舵補助力を増減制御する車両用操舵装置の技術分野に属する。 The present invention belongs to the technical field of a vehicle steering apparatus that controls increase / decrease of a driver's steering assist force according to a steering amount.

従来の車両用操舵装置では、先行路の路面μを推測し、低μ路では高μ路よりも操舵補助力を減らして操舵を重くすることにより、車両挙動が不安定となるのを防止している（例えば、特許文献１参照）。
特開平１１−３２１６７０号公報 In the conventional vehicle steering system, the road surface μ of the preceding road is estimated, and the steering assist force is reduced on the low μ road compared to the high μ road to increase the steering, thereby preventing the vehicle behavior from becoming unstable. (For example, refer to Patent Document 1).
JP 11-321670 A

しかしながら、上記従来技術にあっては、路面μに応じて左操舵と右操舵で均一に操舵補助力を変更しているため、左右の路面μが異なるスプリットμ路等において、制動や駆動により車両挙動が乱れた場合には、修正操舵しづらく、運転者は操舵の重さの違いで左右路面μの差を判断しにくいという問題がある。 However, in the above prior art, since the steering assist force is uniformly changed by left steering and right steering according to the road surface μ, the vehicle is applied by braking or driving on a split μ road where the left and right road surfaces μ are different. When the behavior is disturbed, there is a problem that it is difficult to perform the correction steering, and it is difficult for the driver to determine the difference between the left and right road surface μ due to the difference in the steering weight.

本発明は、上記問題に着目してなされたもので、その目的とするところは、左右路面μの違いを操舵の重さの差として運転者に伝達できる車両用操舵装置を提供することにある。 The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a vehicle steering apparatus that can transmit a difference in right and left road surface μ to a driver as a difference in steering weight. .

上記目的を達成するため、本発明では、操舵手段に加わる操舵量を検出する操舵量検出手段と、転舵輪を転舵させる舵取機構に操舵補助力を加減算する動力源と、前記操舵量検出手段による操舵量に応じて操舵補助力を増減するように前記動力源を駆動制御する操舵制御手段と、を備えた車両操舵装置において、
左右輪それぞれの路面μを推測する路面μ推測手段を設け、
前記操舵制御手段は、左右輪の路面μに所定値以上の差があるとき、左操舵時と右操舵時の操舵補助力を変更することを特徴とする。 In order to achieve the above object, in the present invention, the steering amount detecting means for detecting the steering amount applied to the steering means, the power source for adding / subtracting the steering assist force to the steering mechanism for turning the steered wheels, and the steering amount detection In a vehicle steering apparatus comprising: a steering control unit that drives and controls the power source so as to increase or decrease a steering assist force according to a steering amount by the unit.
Provide road surface μ estimation means to estimate the road surface μ of each of the left and right wheels,
The steering control means changes the steering assist force during left steering and right steering when there is a difference of a predetermined value or more in the road surface μ between the left and right wheels.

よって、本発明の車両用操舵装置にあっては、左右路面μに所定値以上の差があるとき、左操舵時と右操舵時とで異なる操舵反力となるため、左右路面μの違いを操舵の重さの差として運転者に伝達できる。 Therefore, in the vehicle steering device of the present invention, when there is a difference of a predetermined value or more in the left and right road surface μ, the steering reaction force differs between left steering and right steering. This can be transmitted to the driver as the difference in steering weight.

以下に、本発明の車両用操舵装置を実施する最良の形態を、実施例１〜３に基づいて説明する。 Below, the best form which implements the steering device for vehicles of the present invention is explained based on Examples 1-3.

まず、構成を説明する。
図１は、実施例１の車両用操舵装置の構成を示すブロック図である。
実施例１の車両用操舵装置は、舵取り操作用のハンドル（操舵手段）１と舵取り動作を行う舵取機構２とを連結する操舵軸３に、ハンドル１に加わる操舵トルクを検出するトルクセンサ（操舵状態検出手段）４と操舵力補助用のモータ（動力源）５とが配置された、いわゆる電動パワーステアリングシステムである。 First, the configuration will be described.
FIG. 1 is a block diagram illustrating the configuration of the vehicle steering apparatus according to the first embodiment.
The vehicle steering apparatus according to the first embodiment includes a torque sensor that detects a steering torque applied to the handle 1 to a steering shaft 3 that connects a steering handle 1 for steering operation and a steering mechanism 2 that performs a steering operation. This is a so-called electric power steering system in which a steering state detecting means) 4 and a steering force assisting motor (power source) 5 are arranged.

ハンドル１は、図示しない車室内部に運転者と対向するように、軸周りに回転可能に固定されている。舵取機構２は、操舵軸３の下端に一体形成されたピニオン６と、これに噛合するラック軸７とを備えるラック&ピニオン式の舵取り装置により構成される。 The handle 1 is fixed so as to be rotatable around an axis so as to face the driver in a vehicle interior (not shown). The steering mechanism 2 is constituted by a rack and pinion type steering device including a pinion 6 integrally formed at the lower end of the steering shaft 3 and a rack shaft 7 meshing with the pinion 6.

ラック軸７は、図示しない車両前部に、左右方向摺動可能に固定され、ラック軸７の両端は、左右のタイロッド８，９を介して、操向用の前輪１０，１１に連結されている。操舵を補助するモータ５は、モータ５の発生トルクを操舵軸３の回転トルクに変換するような減速機１２を介して、操舵軸３に結合されている。また、モータ５のモータ軸には、モータ５の回転数を検知するモータ速度センサ（操舵状態検出手段）２２が取り付けられている。 The rack shaft 7 is fixed to a front portion of the vehicle (not shown) so as to be slidable in the left-right direction. Both ends of the rack shaft 7 are connected to steering front wheels 10 and 11 via left and right tie rods 8 and 9. Yes. The motor 5 that assists steering is coupled to the steering shaft 3 via a speed reducer 12 that converts torque generated by the motor 5 into rotational torque of the steering shaft 3. A motor speed sensor (steering state detecting means) 22 that detects the number of rotations of the motor 5 is attached to the motor shaft of the motor 5.

後輪１６，１７は、図示しない車体に回転軸１８，１９を介して固定されている。回転軸１８，１９には、軸力センサ（制動状態判断手段および駆動状態判断手段）２０，２１が取り付けられている。また、車体には車体の前後Ｇを計測する前後Ｇセンサ２３が取り付けられている。 The rear wheels 16 and 17 are fixed to a vehicle body (not shown) via rotary shafts 18 and 19. Axial force sensors (braking state determination means and drive state determination means) 20 and 21 are attached to the rotary shafts 18 and 19, respectively. Further, a front / rear G sensor 23 for measuring the front / rear G of the vehicle body is attached to the vehicle body.

コントローラ（操舵制御手段）１３には、トルクセンサ４からの操舵トルク信号と、軸力センサ２０，２１からの後輪２輪の横力信号と、前後Ｇセンサ２３からの前後Ｇ信号と、車速センサ１４からの車速信号、モータ速度センサ２２からのモータ速度信号等が入力される。コントローラ１３は、各センサからの信号に基づいてモータ５を駆動制御し、運転者の操舵力（運転者に伝達される操舵反力）を調整する。モータ５の The controller (steering control means) 13 includes a steering torque signal from the torque sensor 4, lateral force signals for the two rear wheels from the axial force sensors 20 and 21, front and rear G signals from the front and rear G sensor 23, and vehicle speed. A vehicle speed signal from the sensor 14, a motor speed signal from the motor speed sensor 22, and the like are input. The controller 13 controls the driving of the motor 5 based on the signal from each sensor and adjusts the driver's steering force (steering reaction force transmitted to the driver). Of motor 5

図２は、実施例１のコントローラ１３の制御ブロック図であり、コントローラ１３は、駆動電流算出部Ａと補正電流算出部Ｂとを備えている。
電動パワーステアリングシステムにおいては、運転者の操舵力を低減するために、駆動電流算出部Ａによりモータ５の駆動電流値を算出する。運転者によりハンドル１が操作されると、機械的な連結により前輪１０，１１が操向される。この時の負荷は、トルクセンサ４により捩れ操舵トルクとして検出される。トルクセンサ４の出力は、駆動電流算出部Ａに与えられる。さらに、駆動電流算出部Ａには、モータ速度センサ２２の出力と、車速センサ１４の出力が与えられる。 FIG. 2 is a control block diagram of the controller 13 according to the first embodiment. The controller 13 includes a drive current calculation unit A and a correction current calculation unit B.
In the electric power steering system, the drive current calculation unit A calculates the drive current value of the motor 5 in order to reduce the driver's steering force. When the handle 1 is operated by the driver, the front wheels 10 and 11 are steered by mechanical connection. The load at this time is detected as a torsional steering torque by the torque sensor 4. The output of the torque sensor 4 is given to the drive current calculation unit A. Further, the output of the motor speed sensor 22 and the output of the vehicle speed sensor 14 are given to the drive current calculation unit A.

駆動電流算出部Ａは、操舵トルクから車速に応じた操舵トルク−ベースアシスト電流マップ２５を参照し、ベースアシスト電流値を算出する。また、モータ５の回転速度およびその微分値、車速等に基づいて、慣性補償電流値、ダンピング補償電流値および戻り補償電流値を演算し、これらをベースアシスト電流値に加算してモータ５の基本駆動電流値を算出する。 The drive current calculation unit A calculates a base assist current value by referring to the steering torque-base assist current map 25 corresponding to the vehicle speed from the steering torque. Further, based on the rotational speed of the motor 5, its differential value, vehicle speed, etc., an inertia compensation current value, a damping compensation current value, and a return compensation current value are calculated, and these are added to the base assist current value to calculate the basic of the motor 5. A drive current value is calculated.

補正電流算出部Ｂは、路面μ推測手段２６により、右後輪軸力センサ２０と左後輪軸力センサ２１の出力と、モータ速度センサ２２の出力の積分値に基づいて、左右路面μをそれぞれ算出する。 The correction current calculation unit B calculates the left and right road surface μ by the road surface μ estimation means 26 based on the integrated values of the outputs of the right rear wheel axial force sensor 20 and the left rear wheel axial force sensor 21 and the motor speed sensor 22, respectively. To do.

続いて、左右路面μの差から、補正電流マップ２７に基づいて、第１の補正電流値を算出する。補正電流マップ２７は、左右路面μの差が所定値よりも小さいとき、第１の補正電流値がゼロとなり、左右路面μの差が所定値以上のとき、左の路面μが右より高い場合は、偏差に略比例した正の補正電流値、逆に右の路面μが左より高い場合は、偏差に略比例した負の補正電流値となるように設定されている。 Subsequently, a first correction current value is calculated based on the correction current map 27 from the difference between the left and right road surface μ. The correction current map 27 indicates that the first correction current value is zero when the difference between the left and right road surface μ is smaller than a predetermined value, and the left road surface μ is higher than the right when the difference between the left and right road surface μ is equal to or greater than the predetermined value. Is set to be a positive correction current value substantially proportional to the deviation, and conversely, when the right road surface μ is higher than the left, a negative correction current value is substantially proportional to the deviation.

補正電流算出部Ｂは、前後Ｇセンサ２３の出力から、第１の補正係数マップ２８に基づいて、補正係数を設定し、これを第１の補正電流に乗算して第２の補正電流値を算出する。第１の補正係数マップ２８は、車両が所定の加速度以上のとき加速を行っているとき（駆動状態）、加速度に略比例した負の補正係数となり、所定の減速度以上の減速を行っているとき（制動状態）、減速度に略比例した正の補正係数となるように設定されている。また、所定の加速度より低い加速度、または所定の減速度よりも小さい減速度のとき（非制駆動状態）、加速度に略反比例した正の補正係数、または減速度に略比例した正の補正係数となるように設定されている。 The correction current calculation unit B sets a correction coefficient from the output of the front / rear G sensor 23 based on the first correction coefficient map 28, and multiplies the first correction current by the first correction current value to obtain the second correction current value. calculate. The first correction coefficient map 28 is a negative correction coefficient that is substantially proportional to the acceleration when the vehicle is accelerating when the acceleration is equal to or higher than a predetermined acceleration (driving state), and is decelerating more than a predetermined deceleration. Sometimes (braking state), the positive correction coefficient is set to be approximately proportional to the deceleration. In addition, when the acceleration is lower than the predetermined acceleration or the deceleration is lower than the predetermined deceleration (non-braking / driving state), a positive correction coefficient approximately inversely proportional to the acceleration or a positive correction coefficient approximately proportional to the deceleration It is set to be.

コントローラ１３は、算出した基本駆動電流値と第２の補正電流値とを加算して目標電流値を算出し、モータ電流センサ２４により検出される実電流値が目標電流値と一致するようにモータ５の駆動電流を制御する。モータ５へ供給される電源は、バッテリ１５により与えられる。 The controller 13 calculates the target current value by adding the calculated basic drive current value and the second correction current value, and the motor so that the actual current value detected by the motor current sensor 24 matches the target current value. 5 is controlled. Power supplied to the motor 5 is provided by a battery 15.

次に、作用を説明する。
［路面μ推測方法］
ここで、路面μ推測手段２６で実行される路面μの推測方法について説明する。
タイヤのコーナリングパワーＣｐは、Fiala理論から、下記の式(1)のように表される。
Ｃp＝Ｋ（1−0.0166Ｋ／μ₀Ｌ） …(1)
ただし、Ｋ：コーナリングスティフネス、μ₀：路面摩擦係数、Ｌ：接地荷重 Next, the operation will be described.
[Road surface μ estimation method]
Here, the road surface μ estimation method executed by the road surface μ estimation means 26 will be described.
The tire cornering power Cp is expressed by the following formula (1) from the Fiala theory.
Cp = K (1-0.0166K / μ ₀ L) (1)
Where K: cornering stiffness, μ ₀ : road friction coefficient, L: contact load

すなわち、路面摩擦係数μ₀が低いほどタイヤのコーナリングパワーＣpが減少するので、左右後輪１６，１７の路面反力すなわち軸力センサ２０，２１の出力は、路面μの低下に応じて小さくなる。従って、操舵角並びに左右後輪１６，１７の軸力を実測し、操舵角に対する実軸力と、予め内部モデルとして設定された基準軸力とを比較すれば、各輪の路面μを推定することができる。 That is, as the road surface friction coefficient μ ₀ is lower, the cornering power Cp of the tire decreases, so the road surface reaction force of the left and right rear wheels 16, 17, that is, the output of the axial force sensors 20, 21 becomes smaller as the road surface μ decreases. . Accordingly, the road surface μ of each wheel is estimated by actually measuring the steering angle and the axial forces of the left and right rear wheels 16 and 17 and comparing the actual axial force with respect to the steering angle and a reference axial force set in advance as an internal model. be able to.

［制駆動状態に応じた左右操舵時の操舵反力変更作用］
(a) 左路面μ>右路面μ、かつ制動状態の場合は、まず左右路面μの差に略比例した操舵右方向への第１の補正電流値が算出され、これに正の補正係数が掛けられるため、補正電流算出部Ｂからは右方向への第２の補正電流値が出力される。 [Steering reaction force change action during left and right steering according to braking / driving state]
(a) When the left road surface μ> the right road surface μ and in a braking state, first, a first correction current value in the steering right direction that is substantially proportional to the difference between the left and right road surfaces μ is calculated, and a positive correction coefficient is added thereto. Therefore, the correction current calculation unit B outputs the second correction current value in the right direction.

その結果、右操舵はアシスト電流が増えて操舵が軽くなり、左操舵はアシスト電流が減少し操舵が重くなる。左右μスプリット路面での制動は、路面μが高い方へ車両は回転するので、(a)の状態では左路面側に車両は回転しようとするが、車両挙動をさらに不安定にさせる左操舵を重くすることで車両挙動のさらなる悪化を防止し、車両挙動を抑制させる右操舵を軽くすることで短時間での車両挙動修正が容易となる。 As a result, the right steering increases the assist current and lightens the steering, while the left steering decreases the assist current and increases the steering. When braking on the left and right μ-split road surfaces, the vehicle rotates toward the higher road surface μ.Therefore, in the state of (a), the vehicle tries to rotate to the left road surface side, but left steering that further destabilizes the vehicle behavior is performed. By increasing the weight, it is possible to prevent further deterioration of the vehicle behavior, and to lighten the right steering that suppresses the vehicle behavior to facilitate vehicle behavior correction in a short time.

また、左右路面μ差と減速度とに略比例して車両挙動は不安定になるが、左右路面μ差と減速度とに略比例して補正しているため、路面状態や減速度に応じた操舵力を実現できる。 In addition, although the vehicle behavior becomes unstable in proportion to the left and right road surface μ difference and deceleration, it is corrected in proportion to the left and right road surface μ difference and deceleration, so it depends on the road surface condition and deceleration. Steering force can be realized.

(b) 右路面μ>左路面μ、かつ制動状態の場合は、まず操舵左方向への第１の補正電流値が算出され、これに正の補正係数が掛けられるため、補正電流算出部Ｂからは左方向への第２の補正電流値が出力される。 (b) When the right road surface μ> the left road surface μ and the braking state, the first correction current value in the left direction of the steering is first calculated, and this is multiplied by a positive correction coefficient, so that the correction current calculation unit B Outputs a second correction current value in the left direction.

その結果、左操舵はアシスト電流が増えて操舵が軽くなり、右操舵はアシスト電流が減少し操舵が重くなる。左右μスプリット路面での制動は路面μが高い方へ車両は回転するので、(b)の状態では右路面に車両は回転しようとするが、車両挙動をさらに不安定にさせる右操舵を重くすることで車両挙動のさらなる悪化を防止し、車両挙動を抑制させる左操舵を軽くすることで短時間での車両挙動修正が容易となる。 As a result, the left steering increases the assist current and lightens the steering, and the right steering decreases the assist current and increases the steering. When braking on the left and right μ-split roads, the vehicle rotates toward the higher road surface μ, so in the state of (b), the vehicle tries to rotate to the right road surface, but the right steering that makes the vehicle behavior more unstable becomes heavy. Thus, further deterioration of the vehicle behavior is prevented, and the left behavior for suppressing the vehicle behavior is lightened, so that the vehicle behavior can be easily corrected in a short time.

(c) 左路面μ>右路面μ、かつ非制駆動状態の場合は、まず加速度に略比例した操舵右方向への第１の補正電流値が算出され、これに正の補正係数が掛けられるため、補正電流算出部Ｂからは右方向への第２の補正電流値が出力される。 (c) When the left road surface μ> the right road surface μ and the non-braking / driving state, the first correction current value in the steering right direction that is substantially proportional to the acceleration is first calculated, and this is multiplied by a positive correction coefficient. Therefore, the correction current calculation unit B outputs the second correction current value in the right direction.

その結果、右操舵はアシスト電流が増えて操舵が軽くなり、左操舵はアシスト電流が減少し操舵が重くなる。従って、路面μの低い右へ転舵すると操舵が軽くなることで、運転者へ右路面のμが低いことを伝達でき、路面μの高い左へ転舵すると操舵が重くなることで、運転者へ左路面のμが高いことを伝達できる。 As a result, the right steering increases the assist current and lightens the steering, while the left steering decreases the assist current and increases the steering. Therefore, when steering to the right with a low road surface μ, the steering becomes lighter, so it can be transmitted to the driver that the μ of the right road surface is low, and when steering to the left with a high road surface μ, the steering becomes heavier. Can convey that μ on the left road surface is high.

(d) 右路面μ>左路面μ、かつ非制駆動状態の場合は、まず加速度に略比例した操舵左方向への第１の補正電流値が算出され、これに正の補正係数が掛けられるため、補正電流算出部Ｂからは左方向への第２の補正電流値が出力される。 (d) When the right road surface μ> the left road surface μ and the non-braking / driving state, the first correction current value in the left direction of the steering substantially proportional to the acceleration is first calculated and multiplied by a positive correction coefficient. Therefore, the correction current calculation unit B outputs the second correction current value in the left direction.

その結果、左操舵はアシスト電流が増えて操舵が軽くなり、右操舵はアシスト電流が減少し操舵が重くなる。従って、路面μの低い左へ転舵すると操舵が軽くなることで、運転者へ左路面のμが低いことを伝達でき、路面μの高い右へ転舵すると操舵が重くなることで、運転者へ右路面のμが高いことを伝達できる。 As a result, the left steering increases the assist current and lightens the steering, and the right steering decreases the assist current and increases the steering. Therefore, when steering to the left with a low road surface μ, the steering becomes lighter, so it can be transmitted to the driver that the μ of the left road surface is low, and when steering to the right with a high road surface μ, the steering becomes heavier. Can convey that μ on the right road surface is high.

(e) 左路面μ>右路面μ、かつ駆動状態の場合は、まず左右路面μの差に略比例した操舵右方向への第１の補正電流値が算出され、これに負の補正係数が掛けられるため、補正電流算出部Ｂからは左方向への第２の補正電流値が出力される。 (e) When the left road surface μ> the right road surface μ and the driving state, the first correction current value in the right direction of the steering is calculated which is approximately proportional to the difference between the left and right road surfaces μ, and a negative correction coefficient is added to this. Therefore, the correction current calculation unit B outputs a second correction current value in the left direction.

その結果、左操舵はアシスト電流が増えて操舵が軽くなり、右操舵はアシスト電流が減少し操舵が重くなる。左右μスプリット路面での駆動は路面μが低い方へ車両は回転するので、(e)の状態では右路面に車両は回転しようとするが、車両挙動をさらに不安定にさせる右操舵を重くすることで車両挙動のさらなる悪化を防止し、車両挙動を抑制させる左操舵を軽くすることで短時間での車両挙動修正が容易となる。 As a result, the left steering increases the assist current and lightens the steering, and the right steering decreases the assist current and increases the steering. When driving on the left and right μ-split road surface, the vehicle rotates toward the lower road surface μ, so in the state of (e), the vehicle tries to rotate on the right road surface, but the right steering that makes the vehicle behavior more unstable becomes heavy. Thus, further deterioration of the vehicle behavior is prevented, and the left behavior for suppressing the vehicle behavior is lightened, so that the vehicle behavior can be easily corrected in a short time.

また、左右路面μ差と加速度とに略比例して車両挙動は不安定になるが、左右路面μ差と加速度とに略比例して補正しているため、路面状態や加速度に応じた操舵力を実現できる。 In addition, the vehicle behavior becomes unstable in proportion to the difference between the left and right road surface μ and the acceleration, but since the correction is made in proportion to the difference in the left and right road surface μ and the acceleration, the steering force corresponding to the road surface condition and the acceleration. Can be realized.

(f) 右路面μ>左路面μ、かつ駆動状態の場合は、まず左右路面μの差に略比例した操舵左方向への第１の補正電流値が算出され、これに負の補正係数が掛けられるため、補正電流算出部Ｂからは右方向への第２の補正電流値が出力される。 (f) When the right road surface μ> the left road surface μ and in the driving state, first, a first correction current value in the left direction of steering substantially proportional to the difference between the left and right road surfaces μ is calculated, and a negative correction coefficient is added thereto. Therefore, the correction current calculation unit B outputs the second correction current value in the right direction.

その結果、右操舵はアシスト電流が増えて操舵が軽くなり、左操舵はアシスト電流が減少し操舵が重くなる。左右μスプリット路面での駆動は、路面μが低い方へ車両は回転するので、(f)の状態では左路面に車両は回転しようとするが、車両挙動をさらに不安定にさせる左操舵を重くすることで車両挙動のさらなる悪化を防止し、車両挙動を抑制させる右操舵を軽くすることで短時間での車両挙動修正が容易となる。 As a result, the right steering increases the assist current and lightens the steering, while the left steering decreases the assist current and increases the steering. When driving on the left and right μ-split road surface, the vehicle rotates toward the lower road surface μ, so in the state of (f), the vehicle tries to rotate to the left road surface, but the left steering which makes the vehicle behavior more unstable is heavy. By doing so, further deterioration of the vehicle behavior is prevented, and right-hand steering for suppressing the vehicle behavior is lightened, so that the vehicle behavior can be easily corrected in a short time.

次に、効果を説明する。
実施例１の車両用操舵装置にあっては、下記に列挙する効果が得られる。 Next, the effect will be described.
In the vehicle steering apparatus according to the first embodiment, the following effects can be obtained.

(1) コントローラ１３は、左右輪の路面μに所定値以上の差があるとき、左操舵時と右操舵時の操舵補助力（アシストトルク）を変更するため、左操舵時と右操舵時とで異なる操舵反力となり、運転者に左右路面μが異なることを判らせることができる。 (1) The controller 13 changes the steering assist force (assist torque) at the time of left steering and right steering when there is a difference of a predetermined value or more between the road surface μ of the left and right wheels. Thus, the steering reaction force differs, and the driver can be made aware that the right and left road surface μ is different.

(2) コントローラ１３は、制動状態のとき、路面μが低い方へ車両移動する操舵時の操舵補助力を、路面μが高い方へ車両移動する操舵時の操舵補助力よりも大きくするため、制動時に高μ路側へヨーレートが発生しやすいスプリットμ路において、路面μが高い方へ車両が回転する場合の、修正操舵が容易になる。 (2) In the braking state, the controller 13 increases the steering assist force at the time of steering that moves the vehicle toward the lower road surface μ than the steering assist force at the time of steering that moves the vehicle toward the higher road surface μ. In the split μ road where the yaw rate is likely to occur on the high μ road side during braking, the correction steering is facilitated when the vehicle rotates toward the higher road surface μ.

(3) コントローラ１３は、駆動状態のとき、路面μが低い方へ車両移動する操舵時の操舵補助力を、路面μが高い方へ車両移動する操舵時の操舵補助力よりも小さくするため、駆動時に低μ路側へヨーレートが発生しやすいスプリットμ路において、路面μが低い方へ車両が回転する場合の、修正操舵が容易になる。 (3) When the controller 13 is in the driving state, the steering assist force at the time of steering that moves the vehicle to the lower road surface μ is smaller than the steering assist force at the time of steering that moves the vehicle to the higher road surface μ. In the split μ road where the yaw rate is likely to occur on the low μ road side during driving, the correction steering is facilitated when the vehicle rotates toward the lower road surface μ.

(4) コントローラ１３は、非制駆動状態のとき、路面μが低い方へ車両移動する操舵時の操舵補助力を、路面μが高い方へ車両移動する操舵時の操舵補助力よりも大きくするため、左右操舵反力を発生させ、運転者に左右路面μが異なることを操舵の重さの差として伝えることができる。 (4) In the non-braking state, the controller 13 increases the steering assist force at the time of steering to move the vehicle to the lower road surface μ than the steering assist force at the time of steering to move the vehicle to the higher road surface μ. Therefore, it is possible to generate a left-right steering reaction force and inform the driver that the left-right road surface μ is different as a difference in steering weight.

(5) コントローラ１３は、左操舵時と右操舵時の操舵力の差を左右路面μの差に略比例させるため、左右路面μの差が操舵反力の大きさとして運転者に伝わりやすい。 (5) Since the controller 13 makes the difference in steering force between left steering and right steering substantially proportional to the difference in the left and right road surface μ, the difference in the left and right road surface μ is easily transmitted to the driver as the magnitude of the steering reaction force.

実施例２では、左右路面μが異なるとき、左操舵時と右操舵時の操舵補助力の差を、車速に応じて変化させる点で、実施例１と異なる。なお、実施例１と同一の構成部位には、同一符号を付して説明を省略する。 The second embodiment differs from the first embodiment in that when the left and right road surface μ is different, the difference in steering assist force during left steering and right steering is changed according to the vehicle speed. In addition, the same code | symbol is attached | subjected to the component same as Example 1, and description is abbreviate | omitted.

図３は、実施例２のコントローラ１３ａの制御ブロック図であり、コントローラ１３ａは、駆動電流算出部Ａと補正電流算出部Ｃとを備えている。補正電流算出部Ｃは、実施例１の補正電流算出部Ｂに対し、第２の補正係数マップ２９を加えた点で構成が異なる。 FIG. 3 is a control block diagram of the controller 13a according to the second embodiment. The controller 13a includes a drive current calculation unit A and a correction current calculation unit C. The correction current calculation unit C is different from the correction current calculation unit B of the first embodiment in that a second correction coefficient map 29 is added.

第２の補正係数マップ２９は、車速が高いほど補正係数が大きくなるように設定されている。補正電流算出部Ｃでは、補正電流マップ２７で算出された補正係数に、第１の補正係数マップ２８で設定された補正係数と、第２の補正係数マップ２９で設定された補正係数とを掛け合わせることにより、第３の補正係数を算出する。 The second correction coefficient map 29 is set so that the correction coefficient increases as the vehicle speed increases. In the correction current calculation unit C, the correction coefficient calculated in the correction current map 27 is multiplied by the correction coefficient set in the first correction coefficient map 28 and the correction coefficient set in the second correction coefficient map 29. The third correction coefficient is calculated by combining them.

コントローラ１３ａでは、算出した基本駆動電流値と第３の補正電流値とを加算して目標電流値を算出し、モータ電流センサ２４により検出される実電流値が目標電流値と一致するようにモータ５の駆動電流を制御する。 The controller 13a calculates the target current value by adding the calculated basic drive current value and the third correction current value, and the motor so that the actual current value detected by the motor current sensor 24 matches the target current value. 5 is controlled.

すなわち、実施例２では、車速に略比例して第３の補正電流値の絶対値が大きくなるため、車速が高いほど、車両挙動を不安定にさせる方向への操舵がより重くなり、車両挙動を抑制させる方向への操舵がより軽くなる。 In other words, in the second embodiment, the absolute value of the third correction current value increases substantially in proportion to the vehicle speed. Therefore, the higher the vehicle speed, the heavier the steering in a direction that makes the vehicle behavior unstable. Steering in the direction to suppress the is lighter.

次に、効果を説明する。
実施例２の車両用操舵装置にあっては、実施例１の(1)〜(5)の効果に加え、下記の効果が得られる。 Next, the effect will be described.
In the vehicle steering apparatus of the second embodiment, in addition to the effects (1) to (5) of the first embodiment, the following effects can be obtained.

(6) コントローラ１３ａは、車速が高いほど左操舵と右操舵の操舵の重さの差を大きくするため、車速が高いほど大きくなる車両挙動変化に対し、車両挙動安定方向となる修正操舵が容易となる。 (6) The controller 13a increases the difference in weight between the left steering and the right steering as the vehicle speed increases. Therefore, it is easy to perform the correction steering in the vehicle behavior stable direction with respect to the vehicle behavior change that increases as the vehicle speed increases. It becomes.

実施例３では、左右路面μが異なるとき、左操舵時と右操舵時の操舵補助力の差を、操舵速に応じて変化させる点で、実施例１と異なる。実施例１と同一の構成部位には、同一符号を付して説明を省略する。 The third embodiment differs from the first embodiment in that when the left and right road surface μ is different, the difference in steering assist force during left steering and right steering is changed according to the steering speed. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

図３は、実施例３のコントローラ１３ｂの制御ブロック図であり、コントローラ１３ｂは、駆動電流算出部Ａと補正電流算出部Ｄとを備えている。補正電流算出部Ｄは、実施例１の補正電流算出部Ｂに対し、第３の補正係数マップ３０を加えた点で構成が異なる。 FIG. 3 is a control block diagram of the controller 13b according to the third embodiment. The controller 13b includes a drive current calculation unit A and a correction current calculation unit D. The correction current calculation unit D is different from the correction current calculation unit B of the first embodiment in that a third correction coefficient map 30 is added.

第３の補正係数マップ３０は、操舵速が高いほど補正係数が大きくなるように設定されている。補正電流算出部Ｄでは、補正電流マップ２７で算出された補正係数に、第１の補正係数マップ２８で設定された補正係数と、第３の補正係数マップ３０で設定された補正係数とを掛け合わせることにより、第４の補正係数を算出する。 The third correction coefficient map 30 is set so that the correction coefficient increases as the steering speed increases. In the correction current calculation unit D, the correction coefficient calculated in the correction current map 27 is multiplied by the correction coefficient set in the first correction coefficient map 28 and the correction coefficient set in the third correction coefficient map 30. By combining them, the fourth correction coefficient is calculated.

コントローラ１３ｂでは、算出した基本駆動電流値と第４の補正電流値とを加算して目標電流値を算出し、モータ電流センサ２４により検出される実電流値が目標電流値と一致するようにモータ５の駆動電流を制御する。 The controller 13b calculates the target current value by adding the calculated basic drive current value and the fourth correction current value, and the motor so that the actual current value detected by the motor current sensor 24 matches the target current value. 5 is controlled.

すなわち、実施例３では、操舵速に略比例して第４の補正電流値が大きくなるため、操舵速が高いほど、車両挙動を不安定にさせる方向への操舵がより重くなり、車両挙動を抑制させる方向への操舵がより軽くなる。 That is, in the third embodiment, the fourth correction current value increases substantially in proportion to the steering speed. Therefore, the higher the steering speed, the heavier the steering in a direction that makes the vehicle behavior unstable, and the vehicle behavior is reduced. Steering in the direction to be suppressed becomes lighter.

次に、効果を説明する。
実施例３の車両用操舵装置にあっては、実施例１の(1)〜(5)の効果に加え、下記の効果が得られる。 Next, the effect will be described.
In the vehicle steering apparatus of the third embodiment, in addition to the effects (1) to (5) of the first embodiment, the following effects can be obtained.

(7) コントローラ１３ｂは、操舵速が高いほど左操舵と右操舵の操舵の重さの差を大きくするため、操舵速が高いほど大きくなる車両挙動変化に対し、車両挙動安定方向となる修正操舵が容易となる。 (7) The controller 13b increases the difference in weight between the left steering and the right steering as the steering speed is higher, so that the corrected steering that becomes the vehicle behavior stable direction with respect to the vehicle behavior change that increases as the steering speed increases. Becomes easy.

（他の実施例）
以上、本発明を実施する最良の形態を、実施例１〜３に基づいて説明したが、本発明の具体的な構成は各実施例に限定されるものではなく、発明の要旨を逸脱しない範囲の設計変更等があっても本発明に含まれる。 (Other examples)
The best mode for carrying out the present invention has been described based on the first to third embodiments. However, the specific configuration of the present invention is not limited to each embodiment, and does not depart from the gist of the invention. Such design changes are included in the present invention.

例えば、実施例１〜３では、本発明を電動パワーステアリングシステムに適用した例を示したが、運転者の操舵状態や車両の走行状態にかかわりなく操舵反力を調整可能な車両用操舵装置に本発明を適用してもよい。例えば、モータで油圧ポンプを駆動し油圧ポンプの力で操舵反力を増減させる、いわゆるモータ駆動油圧パワーステアリングシステムに適用してもよいし、操舵ハンドルとタイヤがメカニカルに接続されておらず、操舵ハンドルの反力を任意に発生可能な、いわゆるステアバイワイヤシステムに適用してもよい。 For example, in the first to third embodiments, an example in which the present invention is applied to an electric power steering system has been described. However, the present invention is applied to a vehicle steering apparatus that can adjust a steering reaction force regardless of a driver's steering state or a vehicle's traveling state. The present invention may be applied. For example, the present invention may be applied to a so-called motor-driven hydraulic power steering system in which a hydraulic pump is driven by a motor and the steering reaction force is increased or decreased by the force of the hydraulic pump, or the steering handle and the tire are not mechanically connected, and steering is performed. You may apply to what is called a steer-by-wire system which can generate | occur | produce the reaction force of a handle arbitrarily.

また、実施例１〜３の構成において、各構成品は相当の機能を持つものであれば、上記以外でも構わないし、取り付け部位が変更されても構わない。例えば、モータ速度センサ２２の代わりにモータ角度を計測するセンサを採用しても構わないし、モータ速度を直接計測せずに、モータ５の逆起電力を利用して算出してもよい。また、後輪横力の計測に左右後輪にそれぞれ軸力センサ２０，２１を付けているが、軸力計以外にロードセルや微小な変位を計測するストロークセンサ等を用いても構わない。 Moreover, in the structure of Examples 1-3, if each component has a considerable function, it may be other than the above, and the attachment site may be changed. For example, instead of the motor speed sensor 22, a sensor that measures the motor angle may be employed, or the motor speed may be calculated using the counter electromotive force of the motor 5 without directly measuring the motor speed. In addition, although the axial force sensors 20 and 21 are attached to the left and right rear wheels, respectively, for measuring the lateral force of the rear wheel, a load cell, a stroke sensor for measuring a minute displacement, or the like may be used in addition to the axial force meter.

さらに、路面μを推測する手段および方法は、実施例で例示した以外の一般的な手法を用いて、その手法にあった計測手段に変更してもよい。例えば、各輪の回転速度と制駆動状態から各輪のスリップ率を算出し、スリップ率から各輪の路面μを推測する手法およびセンサを用いてもよいのは言うまでもない。 Furthermore, the means and method for estimating the road surface μ may be changed to a measuring means suitable for the method using a general method other than that exemplified in the embodiment. For example, it goes without saying that a method and a sensor for calculating the slip ratio of each wheel from the rotational speed of each wheel and the braking / driving state and estimating the road surface μ of each wheel from the slip ratio may be used.

また、実施例１〜３では、左右後輪１６，１７の状態から左右路面μを推測したが、前輪１０，１１の状態から、または４輪の状態から左右路面μを推測してもよい。さらに、左操舵時と右操舵時の操舵補助力の差を、車速と操舵速の両方に応じて変更してもよい。加えて、モータ回転速度、すなわち操舵速を積分することで操舵角としているが、操舵速の代わりにハンドル１の回転角度を直接計測してもよい。 In Examples 1 to 3, the left and right road surface μ is estimated from the state of the left and right rear wheels 16 and 17, but the left and right road surface μ may be estimated from the state of the front wheels 10 and 11 or from the state of four wheels. Further, the difference in steering assist force during left steering and right steering may be changed according to both the vehicle speed and the steering speed. In addition, although the steering angle is obtained by integrating the motor rotation speed, that is, the steering speed, the rotation angle of the handle 1 may be directly measured instead of the steering speed.

実施例１の車両用操舵装置の構成を示すブロック図である。1 is a block diagram illustrating a configuration of a vehicle steering apparatus according to a first embodiment. 実施例１のコントローラ１３の制御ブロック図である。FIG. 3 is a control block diagram of a controller 13 according to the first embodiment. 実施例２のコントローラ１３ａの制御ブロック図である。FIG. 6 is a control block diagram of a controller 13a according to a second embodiment. 実施例３のコントローラ１３ｂの制御ブロック図である。It is a control block diagram of the controller 13b of Example 3.

Explanation of symbols

１ハンドル
２舵取り機構
３操舵軸
４トルクセンサ
５モータ
６ピニオン
７ラック
８，９タイロッド
１０，１１前輪
１２減速機
１３，１３ａ，１３ｂコントローラ
１４車速センサ
１５バッテリ
１６，１７後輪
１８，１９後輪回転軸
２０，２１軸力センサ
２２モータ角度センサ
２３横Ｇセンサ
２４モータ電流センサ
２５操舵トルク−ベースアシスト電流マップ
２６路面μ推測手段
２７補正電流マップ
２８第１の補正係数マップ
２９第２の補正係数マップ
３０第３の補正係数マップ
DESCRIPTION OF SYMBOLS 1 Handle 2 Steering mechanism 3 Steering shaft 4 Torque sensor 5 Motor 6 Pinion 7 Rack 8, 9 Tie rod 10, 11 Front wheel 12 Reducer 13, 13a, 13b Controller 14 Vehicle speed sensor 15 Battery 16, 17 Rear wheel 18, 19 Rear wheel rotation Axes 20, 21 Axial force sensor 22 Motor angle sensor 23 Lateral G sensor 24 Motor current sensor 25 Steering torque-base assist current map 26 Road surface μ estimation means 27 Correction current map 28 First correction coefficient map 29 Second correction coefficient map 30 Third correction coefficient map

Claims

Steering amount detecting means for detecting a steering amount applied to the steering means, a power source for adding / subtracting steering assisting force to a steering mechanism for turning the steered wheels, and steering assisting force according to the steering amount by the steering amount detecting means. In a vehicle steering apparatus comprising: a steering control unit that drives and controls the power source so as to increase or decrease,
Provide road surface μ estimation means to estimate the road surface μ of each of the left and right wheels,
The vehicle steering apparatus according to claim 1, wherein the steering control means changes a steering assist force during left steering and right steering when there is a difference of a predetermined value or more in the road surface μ between the left and right wheels.

The vehicle steering apparatus according to claim 1,
Braking state determination means for determining whether or not the braking state is provided,
The steering control means, when in a braking state, increases a steering assist force at the time of steering that moves the vehicle toward a lower road surface μ than a steering assist force at the time of steering that moves the vehicle toward a higher road surface μ. A vehicle steering system.

The vehicle steering apparatus according to claim 1 or 2,
Drive state determination means for determining whether or not the drive state is provided,
The steering control means, when in a driving state, makes a steering assist force at the time of steering to move the vehicle to a lower road surface μ smaller than a steering assist force at the time of steering to move the vehicle to a higher road surface μ. A vehicle steering system.

The vehicle steering apparatus according to any one of claims 1 to 3,
When the steering control means is in a non-braking state and a non-driving state, the steering assist force at the time of steering when the vehicle moves toward the lower road surface μ, and the steering assist force at the time of steering when the vehicle moves toward the higher road surface μ A vehicle steering apparatus characterized by being made larger than the above.

The vehicle steering apparatus according to any one of claims 1 to 4, wherein:
The vehicle steering apparatus characterized in that the steering control means makes a difference in steering assist force between left steering and right steering substantially proportional to a difference in left and right road surface μ.

The vehicle steering apparatus according to any one of claims 1 to 5,
The steering control means changes the difference in steering assist force between left steering and right steering according to at least one of a vehicle speed and a steering speed.