JP4089637B2 - Power steering device for vehicle and disturbance estimation device for vehicle - Google Patents

Description

  The present invention relates to a vehicle power steering device that controls a steering assist state of a vehicle in consideration of disturbance applied in a lateral direction with respect to the vehicle, and a vehicle disturbance estimation device that estimates the disturbance.

When a car is running, steering is often affected by various disturbances. Focusing on this point, a technique for controlling the steering system of the vehicle according to the disturbance that the vehicle receives during traveling has been developed.
For example, in Patent Document 1, so-called disturbance suppression performance that prevents disturbances such as cross winds applied to the vehicle from affecting the steering operation of the driver can be improved by steering assist control using an electric power steering device. Things have been proposed.

In this technique, in the control of the steering reaction force (corresponding to the steering assist force), the steering angle component T1 of the steering reaction force based on the steering angle (= the gain obtained by multiplying the steering angle) and the damping based on the steering angular velocity. A component T2 (= steering angular velocity multiplied by gain), a first vehicle behavior suppression component T3 based on vehicle yaw rate (= yaw rate multiplied by gain), and a second vehicle based on lateral acceleration of the vehicle. Calculate the behavior suppression component T4 (= lateral acceleration multiplied by gain) and the road surface component T5 (= steering reaction force multiplied by gain) based on the steering reaction force, as in the following equation: These steering reaction force components T1, T2, T3, T4, and T5 are added to determine the target steering reaction force Ts, and the output torque of the reaction force motor (corresponding to the steering assist electric motor), that is, the steering handle Steering reaction force for this target To return control to the steering reaction force Ts.
Ts = T1 + T3 + T4 + T5-T2

  On the other hand, as a technique of automatic steering, Patent Document 2 discloses that in the automatic steering control in which the steering force of the steering device is feedback-controlled so that the lateral position of the own vehicle approaches the reference position determined from the traveling lane marking. When a disturbance such as a side wind or bank acts on the vehicle, the lateral force and yawing moment acting on the vehicle are estimated by calculation, and the lateral force and yawing moment due to the disturbance are offset to feed the steering amount in feedback control. A technique has been proposed in which a steering device is automatically steered based on a value obtained by adding a forward steering amount, and a disturbance determination threshold value is changed according to the traveling state of the host vehicle.

Further, in Patent Document 3, when a straight running state of the vehicle is detected, a disturbance yaw moment amount acting on the vehicle is detected, and a disturbance suppression yaw moment amount is obtained in accordance with the detected disturbance yaw moment amount. A control command value for generating a moment amount by the yaw moment generator is set, and the set control command value is output to the yaw moment generator. Therefore, a technique has been proposed in which the vehicle posture is stabilized against a crosswind disturbance or a road disturbance by a disturbance suppression yaw moment generated by a yaw moment generator based on a control command value.
JP-A-5-105100. JP 2001-97234 A Japanese Patent Laid-Open No. 2002-212380

By the way, in each of the above-mentioned documents, the steering assist state and the steering state are controlled according to the vehicle behavior. However, for disturbances that affect the vehicle behavior, the disturbance that interferes with steering and rather assists steering. There is a disturbance for.
In other words, disturbance factors that affect the lateral movement of the vehicle not only adversely affect the vehicle behavior such as crosswinds and narrow roads, but also assist the steering rather than by the road structure that takes into account the vehicle's running characteristics such as the lateral slope of the road surface. There is something for. For disturbance due to the former factor, we want to suppress the influence on steering as much as possible, but for the lateral gradient disturbance due to the latter gravitational acceleration component etc., it is generally necessary to run smoothly on a curved road, This effect should not be suppressed.

However, in the technique of Patent Document 1, these disturbances cannot be separated, and the gravitational acceleration component necessary for smoothly running on a curved road is also removed as a disturbance, so that appropriate control cannot be performed.
Patent Document 2 describes that the lateral force Y _w and yawing moment N _w acting on the host vehicle due to the disturbance are estimated by calculation. However, the lateral disturbance of the vehicle is obstructed by steering. However, there is no technical idea to separate and control the disturbance to become a disturbance to assist the steering.

Patent Document 3 also describes that the vehicle posture is stabilized against a lateral wind disturbance or a road surface disturbance. However, the lateral disturbance is separated into a disturbance that disturbs steering and a disturbance that assists steering. There is no technical idea to control.
In addition, when separating the lateral disturbance of the vehicle into a disturbance that hinders steering and a disturbance that assists steering, it is possible to more appropriately set the specific type of the lateral disturbance to be estimated. This is important for proper steering assist.

  The present invention has been devised in view of the above-described problems, and estimates the lateral disturbance of a vehicle by separating it into a disturbance that hinders steering and a disturbance that aids steering, rather than a curved road. A vehicle power steering device capable of improving active safety by appropriately performing steering assist so as to suppress the influence of lateral disturbance on steering while ensuring smooth running performance, and An object of the present invention is to provide a vehicle disturbance estimation device.

In order to achieve the above target, a vehicle power steering apparatus according to the present invention is added to an actuator that is mounted on a vehicle and applies steering assist torque to a steering system, vehicle speed detection means that detects the vehicle speed of the vehicle, and the vehicle. A power steering device comprising: steering torque detection means for detecting steering torque; and control means for controlling the actuator based on detection information from the vehicle speed detection means and the steering torque detection means. Based on the steering angle detecting means for detecting the steering angle, the yaw rate detecting means for detecting the yaw rate of the vehicle, the lateral acceleration detecting means for detecting the lateral acceleration of the vehicle, and the steering-vehicle system model of the vehicle, The vehicle speed V detected by the vehicle speed detection means, the steering angle detection means, the yaw rate detection means, and the lateral acceleration detection means, respectively, and the steering. yaw moment from the δ and yaw rate γ and lateral acceleration G _y, a lateral disturbance of the vehicle, the lateral force tends to rotate the lateral force disturbance phi _cw and the vehicle tending to move the vehicle laterally An estimation means for separating and estimating the disturbance φ _mo and the lateral gradient disturbance φ _rb acting on the vehicle by the lateral inclination of the traveling road surface is provided, and the control means, based on the estimation result by the estimation means, A correction means for correcting the steering assist torque applied by the actuator is provided so as to mainly suppress the lateral force disturbance φ _cw and the yaw moment disturbance φ _mo among the lateral disturbances.

An electric motor that is advantageous for carrying out fine steering assist control is suitable as the actuator.
The vehicle further includes steering angular velocity detecting means for detecting the steering angular velocity of the vehicle, the estimating means is configured to further estimate the yaw rate and lateral velocity of the vehicle, and the correcting means includes the steering angular velocity detecting means and the steering angular velocity detecting means. A first correction torque is calculated from the steering angle, the steering angular speed, the vehicle speed, and the yaw rate and lateral speed estimated by the estimation means detected by the steering angle detection means and the vehicle speed detection means, respectively. A second correction torque is calculated from the estimated lateral force disturbance φ _cw , yaw moment disturbance φ _mo, and side gradient disturbance φ _rb, and the steering assist is calculated based on the first correction torque and the second correction torque. It is preferable to correct the torque (claim 2).

Further, the estimating means includes the vehicle speed V, the steering angle δ, the yaw rate γ, and the lateral acceleration G _y detected by the vehicle speed detecting means, the steering angle detecting means, the yaw rate detecting means, and the lateral acceleration detecting means, respectively. It is preferable to provide an observer for estimating the above-described lateral force disturbance φ _cw , yaw moment disturbance φ _mo, and lateral gradient disturbance φ _{rb as the} state quantities from each state quantity (Claim 3).
Further, the correction means calculates the first correction torque by multiplying each of the steering angle, the steering angular speed, the yaw rate, and the lateral speed by a gain set in accordance with the vehicle speed, The second correction torque is calculated by multiplying the lateral force disturbance φ _cw , the yaw moment disturbance φ _mo, and the lateral gradient disturbance φ _rb by a gain that is set according to the vehicle speed, respectively. Preferably, the steering assist torque is corrected based on the correction torque and the second correction torque.

In addition, the vehicle disturbance estimation device of the present invention includes vehicle speed detection means for detecting the vehicle speed V of the vehicle, steering angle detection means for detecting the steering angle δ of the vehicle, and yaw rate detection for detecting the yaw rate γ of the vehicle. Means for detecting a lateral acceleration G _y of the vehicle, a vehicle speed detecting means, a steering angle detecting means, a yaw rate detecting means, and a lateral acceleration based on a steering-vehicle system model of the vehicle. From the vehicle speed V, the steering angle δ, the yaw rate γ, and the lateral acceleration G _y detected by the detection means, the lateral disturbance of the vehicle is caused by the lateral force to move the vehicle laterally. A force disturbance φ _cw , a yaw moment disturbance φ _mo that attempts to rotate the vehicle, and a lateral gradient disturbance φ _rb that acts on the vehicle due to a lateral inclination of the road surface, and an estimation means that separates and estimates It is characterized by.

Further, the estimation means includes vehicle speed V, steering angle δ, yaw rate γ, and lateral acceleration G _y detected by the vehicle speed detecting means, the steering angle detecting means, the yaw rate detecting means, and the lateral acceleration detecting means, respectively. It is preferable to provide an observer for estimating the above-described lateral force disturbance φ _cw , yaw moment disturbance φ _mo, and lateral gradient disturbance φ _{rb as the} state quantities from each state quantity (Claim 6).

According to the vehicle power steering apparatus of the present invention, the lateral disturbance of the vehicle is caused by the lateral force disturbance φ _cw that attempts to move the vehicle laterally by the lateral force and the yaw moment disturbance φ _mo that attempts to rotate the vehicle. And the lateral gradient disturbance φ _rb acting on the vehicle due to the lateral inclination of the road surface, and from this estimation result, the lateral force disturbance φ _cw and the yaw moment disturbance φ _mo are mainly calculated from the lateral disturbance of the vehicle. Since the steering assist torque is applied so as to be suppressed, the steering assist can be appropriately applied.

In other words, the vehicle behavior caused by the side wind and the bottleneck can be grasped as a lateral force disturbance φ _cw and a yaw moment disturbance φ _mo. Of the lateral disturbances of the vehicle, mainly these lateral force disturbance φ _cw and yaw moment disturbance By applying steering assist torque so as to suppress φ _mo , the influence on the side gradient disturbance φ _rb caused by the side gradient of the road surface provided to enable smooth running on a curved road is suppressed. Without disturbing, it is possible to suppress the influence of the disturbance that influences the vehicle behavior as the lateral force disturbance φ _cw and the yaw moment disturbance φ _mo due to a side wind or a narrow road and disturbs the steering, for example, a curved road The active safety can be improved by suppressing the influence of the lateral force disturbance on the steering while ensuring the smooth running performance.

Further, steering angular velocity detection means for detecting the steering angular velocity ω of the vehicle is provided, and the estimation means estimates the vehicle yaw rate γ and lateral velocity v, and the correction means includes steering angular velocity detection means and steering angle detection means. The first correction torque is calculated from the steering angle δ, the steering angular velocity ω, the vehicle speed V detected by the vehicle speed detection means and the vehicle speed V, the yaw rate γ and the lateral speed v estimated by the estimation means, and estimated by the estimation means. If the second correction torque is calculated from the lateral force disturbance φ _cw , the yaw moment disturbance φ _mo, and the lateral gradient disturbance φ _rb, and the steering assist torque is corrected based on the first correction torque and the second correction torque, Steering assist can be performed appropriately (claim 2).

Further, in the estimating means, each state of the steering angle δ, the yaw rate γ, the lateral acceleration G _y and the vehicle speed V detected by the observer by the steering angle detecting means, the yaw rate detecting means, the lateral acceleration detecting means and the vehicle speed detecting means, respectively. The lateral force disturbance φ _cw , the yaw moment disturbance φ _mo, and the side gradient disturbance φ _rb are obtained by estimating the state force side force disturbance φ _cw , yaw moment disturbance φ _mo, and side gradient disturbance φ _rb It is possible to reliably separate and estimate, and it is possible to reliably separate and grasp a disturbance that hinders steering and a disturbance that assists steering (claim 3).

Further, the correction means calculates the first correction torque by multiplying each of the steering angle δ, the steering angular speed ω, the yaw rate γ, and the lateral speed v by a gain set in accordance with the vehicle speed V, and the lateral force. The second correction torque is calculated by multiplying each of the disturbance φ _cw , the yaw moment disturbance φ _mo, and the lateral gradient disturbance φ _rb by a gain set in accordance with the vehicle speed V, and calculating the second correction torque. By correcting the steering assist torque based on the second correction torque, steering assist can be performed more appropriately.

According to the vehicle disturbance estimation device of the present invention, the lateral disturbance of the vehicle is determined by the lateral force from the vehicle speed V, the steering angle δ, the yaw rate γ, and the lateral acceleration G _y based on the steering-vehicle system model. Lateral force disturbance φ _cw trying to move the vehicle laterally, yaw moment disturbance φ _mo trying to rotate the vehicle, and lateral gradient disturbance trying to move the vehicle laterally due to the weight due to the lateral inclination of the road surface Since it is estimated separately from φ _rb , it is possible to reliably separate and grasp the disturbance that hinders steering and the disturbance that assists steering.

Further, in the estimating means, each state of the steering angle δ, the yaw rate γ, the lateral acceleration G _y and the vehicle speed V detected by the observer by the steering angle detecting means, the yaw rate detecting means, the lateral acceleration detecting means and the vehicle speed detecting means, respectively. The lateral force disturbance φ _cw , the yaw moment disturbance φ _mo, and the side gradient disturbance φ _rb are obtained by estimating the state force side force disturbance φ _cw , yaw moment disturbance φ _mo, and side gradient disturbance φ _rb It can be reliably separated and estimated (claim 6).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIGS. 1 to 11 show a power steering apparatus for a vehicle and a disturbance estimation apparatus for a vehicle as an embodiment of the present invention and will be described based on these drawings.
As shown in FIG. 1, the power steering apparatus for a vehicle according to the present embodiment includes an electric motor (here, a DC motor) 11 as a steering actuator, detects the steering operation state of the vehicle and the state of the vehicle, and detects these. A target steering assist amount is set by an ECU (electronic control unit) 30 from the detection result, and the DC motor 11 is controlled so as to obtain this target steering assist amount.

  For example, as shown in FIG. 3, the DC motor 11 includes a steering system (here, rack and pinion 3) including a steering wheel 1, a steering shaft 2, a rack and pinion 3, a tie rod 4, steering wheels (front wheels) 5L, 5R, and the like. ). Of course, this apparatus can be applied not only to the pinion type electric power steering but also to the case where a small motor is added to the hydraulic power steering or the rack assist type electric power steering.

Further, as means for detecting the steering operation state and the vehicle state, a steering wheel angular velocity sensor 21 as steering speed detection means (front wheel steering angular speed detection means) for detecting a steering angular speed (front wheel steering angular speed) ω _{f_s} , and a steering angle (front wheel) A steering angle sensor 22 as a steering angle detection means (front wheel steering angle detection means) for detecting δ _{f_s} , a yaw rate sensor (yaw angular velocity sensor) 23 as a yaw rate detection means for detecting the yaw rate γ _s of the vehicle, A lateral acceleration sensor 24 as a lateral acceleration detecting means for detecting the lateral acceleration G _{y_s} of the vehicle, a vehicle speed detecting means 25 for detecting the vehicle speed V, and a steering torque (input steering torque) _{Th_s} applied by the driver through the steering wheel (handle). And a steering torque detecting means (steering torque sensor) 26 for detecting.

The ECU 30 includes, as functional elements, a basic steering assist amount calculation unit (electric power steering control calculation unit) 31 that calculates a basic steering assist amount (basic assist torque) T _{m_base,} and an estimation that estimates lateral disturbance applied to the vehicle. An observer 32 as a means and a correction means for calculating a steering assist correction amount (assist torque correction amount) corresponding to a disturbance component applied to the steering system and correcting the steering assist amount (disturbance suppression control amount) accordingly. Disturbance suppression correcting means) 33 is provided.

The electric power steering control calculation unit 31 calculates a basic steering assist amount (basic assist torque) T _{m_base} based on the input steering torque _{Th_s} detected by the steering torque detection means 26 and the vehicle speed V detected by the vehicle speed detection means 25. To do.
In observer 32, based on the front wheel steering angle detecting means 22, the yaw rate detecting means 23, the lateral acceleration detecting means 24, a vehicle speed detecting means 25 in each detected the front wheel steering angle [delta] _{f_s,} yaw rate gamma _s, the lateral acceleration G _{y_s,} the vehicle speed V Lateral disturbance applied to the vehicle, etc. [Specifically, lateral force disturbance estimated value (estimated lateral force disturbance φ _cw trying to move the vehicle laterally by lateral force) φ _{cw_e} , yaw moment disturbance estimation Value (estimated value of yaw moment disturbance φ _mo trying to rotate the vehicle) φ _{mo_e} , estimated lateral gradient disturbance value (estimated value of lateral gradient disturbance φ _rb acting on the vehicle due to lateral inclination of the road surface) φ _{rb_e} , lateral The estimated speed value v _e and the estimated yaw rate value γ _e ] are estimated.

From the function (estimating means) for estimating the lateral disturbance and the like, the front wheel steering angle detecting means 22, the yaw rate detecting means 23, the lateral acceleration detecting means 24, and the vehicle speed detecting means 25, the vehicle disturbance according to the present embodiment. An estimation device is configured.
The correction means 33 includes a steering assist correction amount calculation unit (disturbance suppression control calculation unit) 34 for calculating a correction steering assist amount (correction assist torque) T _{m_add} and a correction assist torque T added to a basic assist torque T _{m_base. An} adder 35 for adding _{m_add} is provided.

The steering assist correction amount calculation unit 34 includes a lateral force disturbance estimated value φ _{cw_e} , a yaw moment disturbance estimated value φ _{mo_e} , a lateral gradient disturbance estimated value φ _{rb_e} , a lateral velocity estimated value v _e , and a yaw rate estimated value estimated by the observer 32. γ _e , the front wheel steering angular speed ω _{f_s} detected by the front wheel steering angular speed detection means 21, the front wheel steering angle δ _{f_s} detected by the front wheel steering angular speed detection means 21, and the vehicle speed V detected by the vehicle speed detection means 25. Based on this, a correction assist torque T _{m_add} corresponding to a disturbance component applied to the steering system is calculated.

That is, the steering assist correction amount calculation unit 34 multiplies the front wheel steering angular velocity ω _{f_s} by the gain K _ω to multiply the front wheel steering angular velocity correspondence correction amount (= K _ω ω _{f_s} ), and multiplies the front wheel steering angle δ _{f_s} by the gain K _δ. front wheel steering angle corresponding correction amount ₍₌ K δ ω _{f_s),} lateral velocity corresponding correction amount in the horizontal velocity estimate v _e is multiplied by a gain _{K v (= K v v e} ) a gain K to the yaw rate estimated value gamma _e yaw rate-dependent correction amount by multiplying the _r a (= K _r gamma _e), respectively calculated, the sum of these correction amounts (first correction _{torque) T m_fb (= K ω ω} f_s + K δ ω f_s + K v v e The basic assist torque T _{m_base} is feedback-corrected by + K _r γ _e ).

Further, the lateral force disturbance estimated value φ _{cw_e} is multiplied by the gain K _{Φ_cw} to _calculate a lateral disturbance corresponding correction amount (second correction torque) T _{m_cw} (= K _{Φ_cw} φ _{cw_e} ), and further, the yaw moment disturbance estimated value φ _{mo_e} lateral disturbance corresponding correction amount by multiplying the gain K _{Fai_mo} (second correction _{torque) T m_mo (= K Φ_mo φ} mo_e) is calculated, the correction amount T _{M_cw,} feedforward the basic assist torque T _{M_base} by T _{M_mo} to correct.
As shown in FIG. 1, the lateral gradient disturbance estimated value φ _{rb_e} is _multiplied by the gain K _{Φ_rb} (= small value) to correct the lateral gradient disturbance corresponding correction amount (second correction torque) T _{m_rb} (= K _{Φ_rb} φ _{rb_e} ). The basic assist torque T _{m_base} may be feedforward corrected using this correction amount, but basically, the lateral force disturbance estimated value φ _{cw_e} and the yaw moment disturbance estimated value φ _{mo_e} are mainly used (or these _Therefore , it is important to feed-forward correct the basic assist torque T _{m_base} so that the influence of the lateral disturbance is eliminated.

Therefore, the control system is configured to suppress only the influence of the lateral wind disturbance among the lateral gradient disturbance, the lateral force disturbance, and the yaw moment disturbance separated by the estimation of the observer 32.
That is, as shown in FIG. 4, the road lateral slope on the curved road is generally provided to cancel the centrifugal force generated by turning the curve and facilitate turning on the curve. In addition, the lateral slope on the straight road is a small value of about 2-3%, but is provided for drainage. In the observer 32, the control system is configured so as to suppress only the influence of the lateral wind disturbance by excluding such a lateral gradient disturbance from the disturbance disturbance target among the lateral disturbances.

The estimation by the observer 32 will be further described. The relationship of each variable related to the DC motor 11 can be modeled into a control block as shown in FIGS. 3 to 5 show the respective parts (parts P1, P2, and P3 partitioned by a one-dot chain line) in FIG. 2 in an enlarged manner.
The parameters in FIGS. 1 and 2 to 5 are shown in Table 1 below.

上式（Ａ）において、ゲインａ₁₁，ａ₁₂，ａ₂₁，ａ₂₂，ｂ₁，ｂ₂はいずれも車速に応じて決定し、ゲインll_(1,1)〜ll_(7,3)はいずれもモータの周波数特性を考慮して数式演算により適正値を設定することができる。 From the relationship shown in FIG. 2, the following equation (A) is derived as an observer state equation.

In the above equation (A), the gains a ₁₁ , a ₁₂ , a ₂₁ , a ₂₂ , b ₁ , b ₂ are all determined according to the vehicle speed, and the gains ll _{(1,1) to} ll ₍ 7,3 ₎ are In either case, an appropriate value can be set by mathematical calculation in consideration of the frequency characteristics of the motor.

Thus, the observer 32, the front wheel steering angle [delta] _{f_s,} yaw rate gamma _s, the lateral acceleration G _{y_s,} the steering torque T _h, as an input variable to each state quantity of the vehicle speed V, the and the lateral velocity estimated value v _e and yaw rate estimated value gamma _e The respective state quantities of the lateral force disturbance estimated value φ _{cw_e} , the yaw moment disturbance estimated value φ _{mo_e,} and the lateral gradient disturbance estimated value φ _{rb_e} can be estimated.
Here, the observer 32 for estimating the side gradient disturbance, the side wind disturbance, and the moment disturbance will be described in more detail.

In designing the observer 32, it is necessary to construct a robust lateral control system, which is based on the following assumptions (a) to (d).
(A) The sensor signal assumes a steering angle, a steer torque, a yaw rate, and a lateral acceleration.
(B) Non-linearity of tire and suspension is not considered.
(C) Since a control system that is robust against lateral disturbance is designed, no driver operation is assumed (Th = 0).

  As shown in FIG. 5, the actual steering system is composed of a mechanical system and a DC motor system. The inertial system is composed of a steering wheel, a DC motor, and a tire, and the elastic system is composed of a torsion bar and a tire. Here, when a differential equation is built around the kingpin, the following equations (1) to (3) are obtained.

ここで、δ_fは前輪実舵角、αはハンドル角（コラム軸回り）、Ｔ_sは路面からのセルフアライニンクトルク、Ｔ_mはＤＣモータの付加トルク、Ｔ_hはドライバトルク（トルクセンサ値）である。なお、系のパラメータＩ_s，Ｃ_s，Ｎ_t，Ｎ_m，Ｋ_tをについては前記の表１に記載する。

Here, [delta] _f the front wheel actual steering angle, alpha is the steering wheel angle (the column axis), T _s is the self-Alai Schimmelpenninck torque from the road surface, T _m is the additional torque of the DC motor, T _h is the driver torque (torque sensor value ). The system parameters I _s , C _s , N _t , N _m , and K _t are described in Table 1 above.

Here, the front wheel actual steering angle δ _f can be measured from the sensor values _Th and α.
When the previous equation (2) is modified, the following equation (4) is obtained.

さらに、ここでは、図６に示すような二輪モデルを車両モデルとする。前輪実舵角δ_fをシステム入力として定義すると、かかるモデルの車両系の運動方程式を次式（５）,（６）のように記述できる。

Furthermore, here, a two-wheel model as shown in FIG. 6 is a vehicle model. If the front wheel actual steering angle δ _f is defined as a system input, the equation of motion of the vehicle system of this model can be described as the following equations (5) and (6).

ここで、ｖは車両の横速度,γは車両のヨーレイト,φは横方向外乱要素であり、φ_moはモーメント外乱成分である。また、パラメータＩ_s，Ｃ_s，Ｎ_t，Ｎ_m，Ｋ_tは前記表１に記載する。

Here, v is the lateral velocity of the vehicle, γ is the yaw rate of the vehicle, φ is a lateral disturbance element, and φ _mo is a moment disturbance component. Parameters I _s , C _s , N _t , N _m , and K _t are listed in Table 1 above.

The above equations (5) and (6) showing differential equations representing the lateral movement and yaw movement of the vehicle are generally well known.
As described above, the lateral disturbance φ is composed of the lateral force disturbance φ _cw and the lateral gradient disturbance φ _rb [see the following equation (7)].

これらの横力外乱φ_cw,ヨーモーメント外乱値φ_mo,横勾配外乱φ_rbは式（５）に外部入力として与えられるが、直接計測することはできない。そこで、これらの横方向外乱の対策として、図７に示すように、オブザーバで外乱を推定し、コントローラ（ＥＣＵ３０内の制御指令系）ではフィードフォワードループによって外乱の影響を近似的に打ち消す制御手法をとった。この手法では、外乱が一定値の場合積分制御と等価である。計測される出力信号である横加速度センサ値は、次式に示すように車両の状態量と横勾配外乱φ_rbとで表現されるが、横力外乱φ_cw及びヨーモーメント外乱φ_moは含まれない。なお、コントローラ３０では横外乱以外の外乱については、車両の各状態量をフィードバックして外乱の影響を抑制している。

These lateral force disturbance φ _cw , yaw moment disturbance value φ _mo , and lateral gradient disturbance φ _rb are given as external inputs to equation (5), but cannot be directly measured. Therefore, as a countermeasure against these lateral disturbances, as shown in FIG. 7, a control method is used in which the disturbance is estimated by an observer, and the controller (control command system in the ECU 30) approximately cancels the influence of the disturbance by a feedforward loop. I took it. This method is equivalent to integral control when the disturbance is a constant value. The lateral acceleration sensor value, which is the output signal that is measured, is expressed by the vehicle state quantity and the lateral gradient disturbance φ _rb as shown in the following equation, but the lateral force disturbance φ _cw and yaw moment disturbance φ _mo are included. Absent. Note that the controller 30 feeds back each state quantity of the vehicle for disturbances other than lateral disturbances to suppress the influence of the disturbances.

By the way, the detection value G _{y — s} of the G sensor is expressed by the equation (8a) on the flat road s having no right and left gradient, but is a disturbance φ _rb having a lateral gradient. Is included, equation (8b) is obtained.

上記の式（８ａ）は、３つの横方向外乱φ_cw，φ_mo，φ_rbを分離できる可能性があることを示しており、式（５），（６），（７），（８ｂ）を整理すると、次の状態方程式（９），（１０）が得られる。

The above equation (8a) indicates that the three lateral disturbances φ _cw , φ _mo , φ _rb may be separated, and the equations (5), (6), (7), (8b) Is obtained, the following state equations (9) and (10) are obtained.

ここで、未知の状態量ｖと横方向外乱φ_cw，φ_mo，φ_rbを同時に推定するオブザーバを設計するために、次式（１１），（１２）に示すように３つの横方向外乱φ_cw，φ_mo，φ_rbを状態量として拡張したモデルを定義する。

Here, in order to design an observer that simultaneously estimates the unknown state quantity v and the lateral disturbances φ _cw , φ _mo , and φ _rb , three lateral disturbances φ as shown in the following equations (11) and (12): _cw, φ _mo, defines an expanded model phi _rb as the quantity of state.

上式（１１），（１２）はｖ,γ,φ_cw，φ_mo，φ_rbの係数行列Ａ,Ｃ（下式）にかかる階級（ｒａｎｋ［Ｃ ＣＡ ・・・ＣＡ^n-1］^T）が状態数（状態量の種類）ｎを満たすので、可観測であり、未知の状態量ｖと未知の外乱φ_cw，φ_rbをオブザーバによって推定することができる。ここで、ｖ,γ,φ_cw，φ_mo，φ_rbは推定結果であり、以下のＬは推定ゲイン行列である。

The above equations (11) and (12) are classes (rank [C CA... CA ⁿ⁻¹ ] ^T ) according to the coefficient matrices A and C (the following equations) of v, γ, φ _cw , φ _mo and φ _rb. Satisfies the number of states (types of state quantities) n, which is observable, and the unknown state quantities v and the unknown disturbances φ _cw and φ _rb can be estimated by the observer. Here, v, γ, φ _cw , φ _mo , and φ _rb are estimation results, and the following L is an estimation gain matrix.

このようなオブザーバのブロック図を模式的に示すと、図８のようになる。
線形ロバストを制御するにあたり、４次の微分方程式を制御対象モデルとして適用すると、この４次モデルは、操舵系モデルの２つの状態変数である前輪実舵角δ_fと前輪実舵角速度δ_f´および車両系の２つの状態変数である横速度ｖとヨーレイトγとで構成される。ここで、横方向外乱φ_cw，φ_mo，φ_rbは外部入力として制御対象に与えられる。なお、前式（１）におけるドライバトルクはゼロと仮定する(Ｔ_h＝０)。

A block diagram of such an observer is schematically shown in FIG.
In controlling the linear robustness, when a fourth-order differential equation is applied as a control target model, the fourth-order model is obtained by the front wheel actual steering angle δ _f and the front wheel actual steering angular velocity δ _f ′, which are two state variables of the steering system model. And two state variables of the vehicle system, the lateral velocity v and the yaw rate γ. Here, the lateral disturbances φ _cw , φ _mo , and φ _rb are given to the controlled object as external inputs. Note that the driver torque in the previous equation (1) is assumed to be zero (T _h = 0).

そして、本ロバスト制御システムは、状態フィードバックループと外乱抑制フィードフォワードループとから構成する。状態フィードバックループは、十分な系の応答性と安定性を確保する。外乱抑制フィードフォワードループは、横風外乱の定常状態における影響を抑制する。式（１４）における制御入力は、次式（１５）〜（１７）により定める。

The robust control system includes a state feedback loop and a disturbance suppression feedforward loop. The state feedback loop ensures sufficient system response and stability. The disturbance suppression feedforward loop suppresses the influence of the crosswind disturbance in the steady state. The control input in equation (14) is determined by the following equations (15) to (17).

ここで,［Ｋω，Ｋδ，Ｋ_v，Ｋγ］は状態フィードバックゲインであり、ＬＧ制御理論によって得られる。状態フィードバックループは,主に系を安定化させることを目的とする。前輪実舵角速度δ_fは、モータの付加電圧と電流から計算することができる。前輪実舵角δ_fは前式（４）から得られる。

Here, [Kω, Kδ, K _v , Kγ] are state feedback gains, which are obtained by LG control theory. The state feedback loop is mainly aimed at stabilizing the system. The front wheel actual steering angular velocity δ _f can be calculated from the additional voltage and current of the motor. The front wheel actual steering angle δ _f is obtained from the previous equation (4).

As described above, v, φ _cw , φ _mo and φ _rb are estimated from the disturbance observer. On the other hand, the disturbance suppression feedforward loop aims to reduce the influence of the side wind disturbance φ _cw and the yaw moment disturbance φ _mo . Specifically, the steady value of the yaw rate caused by the side force disturbance φ _cw and the yaw moment disturbance φ _mo The feed forward gain is determined so that the value is zero. First, when determining the feedforward gain k _{ff_cw} , it is assumed that φ _mo = 0 and φ _rb = 0 in equation (14).

  From the above assumption, the following equation of state (18) is obtained.

定常状態(ｄｘ／ｄｔ＝０)において式（１８）は次式（１９）のように変形される。

In the steady state (dx / dt = 0), the equation (18) is transformed into the following equation (19).

ここで、δ_fss,ｖ_ss,γ_ssは、φ_cwに対するδ_f,ｖ,γの定常値である。従って、この方程式を直接解くと次式（２０）が得られる。

Here, δ _fss , v _ss , and γ _ss are steady values of δ _f , v, and γ with respect to φ _cw . Therefore, the following equation (20) is obtained by directly solving this equation.

外乱によって生じるヨーレイトの定常値を０にするために、式（２０）のγ_ssの行に注目すると、次式（２１）が導出される。

In order to make the steady value of the yaw rate caused by the disturbance zero, paying attention to the row of γ _{ss in} equation (20), the following equation (21) is derived.

従って、式（２１）,（１７）からフィードフォワードゲインＫ_{ff_cw}及びＫ_{ff_mo}を求める次式（２２ａ），（２２ｂ）を得ることができる。

Therefore, the following equations (22a) and (22b) for obtaining the feedforward gains K _{ff_cw} and K _{ff_mo} can be obtained from the equations (21) and (17).

本発明の一実施形態としての車両用パワーステアリング装置は、上述のように構成されているので、操舵アシスト補正手段（操舵アシスト補正量演算部３４及び演算部３５）３３により、前輪舵角速度対応補正量（＝Ｋ_ωω_{f_s}）、前輪舵角対応補正量（＝Ｋ_δω_{f_s}）、横速度対応補正量（＝Ｋ_vｖ_e）、ヨーレイト対応補正量（＝Ｋ_rγ_e）の加算値Ｔ_{m_fb}（＝Ｋ_ωω_{f_s}＋Ｋ_δω_{f_s}＋Ｋ_vｖ_e＋Ｋ_rγ_e）により基本アシストトルクＴ_{m_base}をフィードバック補正するとともに、横力外乱φ_cwに対応した補正量である横方向外乱対応補正量Ｔ_{m_cw}（＝Ｋ_{Φ_cw}φ_{cw_e}）と、ヨーモーメント外乱φ_moに対応した補正量である横方向外乱対応補正量Ｔ_{m_mo}（＝Ｋ_{Φ_mo}φ_{mo_e}）とにより基本アシストトルクＴ_{m_base}をフィードフォワード補正するので、横方向外乱のうちから横勾配外乱を除去した横方向外乱（横風外乱等）φ_cwとヨーモーメント外乱φ_moとを抑制するように電動モータを制御して操舵アシストトルクを与えるので、カーブ路のスムーズな走行性能を確保しながら、操舵への横風外乱の影響を抑制して、アクティブ・セーフティを向上させることができるようになる。

Since the vehicle power steering apparatus according to the embodiment of the present invention is configured as described above, the steering assist correction means (the steering assist correction amount calculation unit 34 and the calculation unit 35) 33 corrects the front wheel steering angular velocity corresponding correction. the amount ₍₌ K ω ω _{f_s),} front wheel steering angle corresponding correction amount ₍₌ K δ ω _{f_s),} lateral velocity corresponding correction amount (= K _{v v e),} the yaw rate corresponding correction amount adding value (= K _r γ _e) the _{T m_fb (= K ω ω f_s} + K δ ω f_s + K v v e + K r γ e) as well as feedback correcting the basic assist torque _T m_base, lateral disturbance corresponding correction is a correction amount corresponding to the lateral force disturbance phi _cw amount _{T m_cw (= K Φ_cw φ cw_e} ), lateral disturbance corresponding correction amount T _{M_mo} a correction amount corresponding to the yaw moment disturbance _{φ mo (= K Φ_mo φ mo_e} ) and by the feed forward correcting the basic assist torque T _{M_base} Because Since lateral disturbance lateral disturbance removal of the horizontal gradient disturbance from among (crosswind disturbance) controls the electric motor so as to suppress the phi _cw and yaw moment disturbance phi _mo to give a steering assist torque, the curved road While ensuring smooth running performance, it is possible to improve the active safety by suppressing the influence of cross wind disturbance on the steering.

Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, each gain _{Kω, Kδ, K v, K} r, K ff_cw, K ff_mo, for K _{Ff_rb,} as it is possible to improve the stability and steering feeling of the system, be set appropriately in accordance with the vehicle speed is important.

It is a block diagram which shows the function structure of the power steering apparatus for vehicles as one Embodiment of this invention. It is a block diagram of the observer which estimates the state quantity of the motor control system concerning the power steering device for vehicles as one embodiment of the present invention. FIG. 3 is a block diagram of a principal part of an observer for estimating a state quantity of a motor control system according to a vehicle power steering apparatus as one embodiment of the present invention, and shows an enlarged portion P1 of FIG. FIG. 3 is a block diagram of a principal part of an observer for estimating a state quantity of a motor control system according to a vehicle power steering apparatus as one embodiment of the present invention, and shows an enlarged portion P2 of FIG. It is a principal part block diagram of the observer which estimates the state quantity of the motor control system concerning the power steering device for vehicles as one Embodiment of this invention, and has expanded and shown the part P3 of FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating a vehicle power steering device as one embodiment of the present invention. It is a figure explaining the horizontal disturbance to the vehicle which drive | works, (a) is a typical top view of the vehicle which drive | works, (b) is a typical rear view of the vehicle which drive | works. It is a mimetic diagram showing a steering system model concerning one embodiment of the present invention. It is a mimetic diagram showing a vehicle system model concerning one embodiment of the present invention. It is a block diagram explaining steering control concerning one embodiment of the present invention. It is a block diagram of an observer explaining steering control concerning one embodiment of the present invention.

Explanation of symbols

11 DC motor 21 Front wheel rudder angular velocity detection means (steering angular velocity detection means)
22 Front wheel rudder angle detecting means (steering angle detecting means)
23 Yaw rate detection means 24 Lateral acceleration detection means 25 Vehicle speed detection means 26 Steering torque detection means 30 Electronic control unit (ECU) as control means
31 Basic control amount setting unit (Electric power steering control calculation unit)
32 Estimation means (observer)
33 Correction means (disturbance suppression correction means)
34 Steering assist correction amount calculation unit (disturbance suppression control calculation unit)
35 Calculation unit

Claims (6)

An actuator mounted on a vehicle for applying steering assist torque to a steering system, vehicle speed detection means for detecting the vehicle speed of the vehicle, steering torque detection means for detecting steering torque applied to the vehicle, vehicle speed detection means, A power steering device comprising control means for controlling the actuator based on detection information from the steering torque detection means,
Steering angle detection means for detecting the steering angle of the vehicle;
Yaw rate detecting means for detecting the yaw rate of the vehicle;
Lateral acceleration detecting means for detecting lateral acceleration of the vehicle;
The vehicle speed V, steering angle δ, and yaw rate γ detected by the vehicle speed detecting means, the steering angle detecting means, the yaw rate detecting means, and the lateral acceleration detecting means based on the vehicle steering-vehicle system model, respectively. And the lateral acceleration G _y , the lateral disturbance of the vehicle, the lateral force disturbance φ _cw that attempts to move the vehicle laterally by lateral force, and the yaw moment disturbance φ _mo that attempts to rotate the vehicle, An estimation means for separating and estimating the lateral gradient disturbance φ _rb acting on the vehicle by the lateral inclination of the traveling road surface;
From the estimation result by the estimation means, the control means is provided with the steering assist torque applied by the actuator so as to suppress mainly the lateral force disturbance φ _cw and the yaw moment disturbance φ _mo among the lateral disturbances of the vehicle. A power steering apparatus for a vehicle, comprising a correcting means for correcting. A steering angular velocity detecting means for detecting the steering angular velocity of the vehicle;
The estimating means is configured to further estimate the yaw rate and lateral velocity of the vehicle;
The correcting means is configured to calculate the first angle based on the steering angle, the steering angular speed, the vehicle speed detected by the steering angular speed detecting means, the steering angle detecting means, and the vehicle speed detecting means, and the yaw rate and lateral speed estimated by the estimating means. 1 correction torque is calculated, a second correction torque is calculated from the lateral force disturbance φ _cw , yaw moment disturbance φ _mo, and lateral gradient disturbance φ _rb estimated by the estimation means, and the first correction torque and 2. The vehicle power steering apparatus according to claim 1, wherein the steering assist torque is corrected based on the second correction torque. The estimating means includes states of the vehicle speed V, the steering angle δ, the yaw rate γ, and the lateral acceleration G _y detected by the vehicle speed detecting means, the steering angle detecting means, the yaw rate detecting means, and the lateral acceleration detecting means, respectively. The vehicle according to claim 1, further comprising an observer for estimating the lateral force disturbance φ _cw , the yaw moment disturbance φ _mo, and the lateral gradient disturbance φ _rb as state quantities from the quantity. Power steering device. The correction means calculates the first correction torque by multiplying each of the steering angle, the steering angular speed, the yaw rate, and the lateral speed by a gain that is set according to the vehicle speed, and the lateral force disturbance φ _cw described above. And the yaw moment disturbance φ _mo and the lateral gradient disturbance φ _rb are multiplied by gains set in accordance with the vehicle speed to calculate the second correction torque, and the first correction torque and the second correction torque are calculated. The power steering apparatus for a vehicle according to any one of claims 1 to 3, wherein the steering assist torque is corrected based on the torque. Vehicle speed detecting means for detecting the vehicle speed V of the vehicle;
Steering angle detection means for detecting the steering angle δ of the vehicle;
A yaw rate detecting means for detecting the yaw rate γ of the vehicle;
Lateral acceleration detecting means for detecting the lateral acceleration G _{y of the} vehicle;
The vehicle speed V, steering angle δ, and yaw rate γ detected by the vehicle speed detecting means, the steering angle detecting means, the yaw rate detecting means, and the lateral acceleration detecting means based on the vehicle steering-vehicle system model, respectively. And the lateral acceleration G _y , the lateral disturbance of the vehicle, the lateral force disturbance φ _cw that attempts to move the vehicle laterally by lateral force, and the yaw moment disturbance φ _mo that attempts to rotate the vehicle, A vehicle disturbance estimation device comprising: estimation means for separating and estimating a lateral gradient disturbance _φrb acting on the vehicle by a lateral inclination of a traveling road surface. The estimating means includes states of the vehicle speed V, the steering angle δ, the yaw rate γ, and the lateral acceleration G _y detected by the vehicle speed detecting means, the steering angle detecting means, the yaw rate detecting means, and the lateral acceleration detecting means, respectively. The vehicle disturbance estimation according to claim 5, further comprising an observer for estimating the lateral force disturbance φ _cw , the yaw moment disturbance φ _mo, and the lateral gradient disturbance φ _rb as state quantities from the quantity. apparatus.

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