JP4123158B2 - 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 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 a reference position determined from the traveling lane marking line. 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.
The present invention was devised in view of the above-described problems, and estimates the lateral disturbance of the vehicle by separating it into a disturbance that hinders steering and a disturbance that aids steering. A vehicle power steering apparatus 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. and a δ and yaw rate γ and lateral acceleration G _y, a lateral disturbance of the vehicle, transverse gradient disturbance phi acting on the vehicle by a transverse inclination of the yaw moment disturbance phi _mo and road surface which tends to rotate the vehicle _rb And an estimation unit that estimates the noise separately, and the control unit applies to the control unit by the actuator so as to mainly suppress the yaw moment disturbance φ _mo among the lateral disturbances of the vehicle based on the estimation result by the estimation unit. And a correction means for correcting the steering assist torque.

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 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. Preferred (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 that an observer for estimating the yaw moment disturbance φ _mo and the lateral gradient disturbance φ _{rb as the} state quantities is provided 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, and the yaw moment disturbance described above. The second correction torque is calculated by multiplying each of φ _mo and the lateral gradient disturbance φ _rb by a gain set in accordance with the vehicle speed, and based on the first correction torque and the second correction torque. It is preferable to correct the steering assist torque (claim 4).

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 means for detecting the yaw rate γ of the vehicle. When the lateral acceleration detecting means for detecting a lateral acceleration G _y of the vehicle, of the vehicle steering - based on the vehicle system model, vehicle speed detecting means and the steering angle detection means and said yaw rate detecting means and the lateral acceleration detected Yaw moment disturbance φ _mo trying to rotate the vehicle and lateral inclination of the road surface from the vehicle speed V, steering angle δ, yaw rate γ, and lateral acceleration G _y detected by the vehicle _Is provided with an observer for estimating each state quantity of the lateral gradient disturbance φ _rb acting on the vehicle by separating the lateral disturbance of the vehicle into the yaw moment disturbance φ _mo and the lateral gradient disturbance φ _rb And estimation means to It is characterized by that example.

According to the vehicle power steering apparatus of the present invention, the lateral disturbance of the vehicle is separated into the yaw moment disturbance φ _{mo that} is intended to rotate the vehicle and the lateral gradient disturbance φ _rb that acts on the vehicle due to the lateral inclination of the traveling road surface. and estimates, from the estimated result, imparting a steering assist torque to suppress predominantly yaw moment disturbance phi _mo of lateral disturbance of the vehicle, it is possible to appropriately applying a steering assist.

In other words, as the vehicle behavior caused by such as a side wind or Tetsuro, it can be grasped as a yaw moment disturbance phi _mo, among lateral disturbance of the vehicle, primarily applying a steering assist torque to suppress the yaw moment disturbance phi _mo By doing so, the side slope disturbance φ _rb caused by the side slope of the road surface provided to enable smooth running on curved roads can be attributed to side winds, narrow roads, etc. without suppressing the effect. As the yaw moment disturbance φ _mo affects the behavior of the vehicle and interferes with steering, the influence can be suppressed.For example, while ensuring smooth running performance on curved roads, the influence of lateral force disturbance on steering can be reduced. It becomes possible to suppress and improve active safety.

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 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, the steering assist is appropriately performed. (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. from the amount, by estimating the yaw moment disturbance phi _mo and horizontal gradient disturbance phi _rb is the state quantity can be estimated reliably separate the yaw moment disturbance phi _mo and horizontal gradient disturbance phi _rb, steering Therefore, it is possible to reliably separate and grasp the disturbance that disturbs the disturbance and the disturbance for assisting the 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 yaw moment The second correction torque is calculated by multiplying each of the disturbance φ _mo and the lateral gradient disturbance φ _rb by a gain set in accordance with the vehicle speed V to obtain the first correction torque and the second correction torque. By correcting the steering assist torque based on this, steering assist can be performed more appropriately (claim 4).

According to the vehicle disturbance estimation device of the present invention, the vehicle lateral disturbance from the vehicle speed V, the steering angle δ, the yaw rate γ, and the lateral acceleration G _y is calculated by the observer based on the steering-vehicle system model. The yaw moment disturbance φ _mo that tries to rotate the vehicle and the lateral gradient disturbance φ _rb that acts on the vehicle due to the lateral inclination of the road surface are estimated separately, so that the disturbance that interferes with steering and rather the steering assist Disturbances can be reliably separated and grasped.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 8 show a vehicle power steering apparatus and a vehicle disturbance estimation apparatus according to an embodiment of the present invention, which will be described with reference to 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 a means for detecting the steering operation state and the vehicle state, a steering wheel angular speed sensor 21 as a 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) ( _Steer angle) steering angle sensor 22 as a steering angle detection means (front wheel steering angle detection means) for detecting δ _{f_s} , yaw rate sensor (yaw angular velocity sensor) 23 as a yaw rate detection means for detecting the yaw rate r _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.
The observer 32 is based on the front wheel steering angle δ _{f — s} , yaw rate r _s , lateral acceleration G _{y — s} , and vehicle speed V detected by the front wheel steering angle detection means 22, yaw rate detection means 23, lateral acceleration detection means 24, and vehicle speed detection means 25, respectively. Lateral disturbance applied to the vehicle, etc. [specifically, yaw moment disturbance estimated value (estimated yaw moment disturbance φ _mo trying to rotate the vehicle by lateral force) φ _{mo_e} , lateral gradient disturbance estimated value (running estimated value of the lateral gradient disturbance phi _rb tending to move the vehicle laterally by weight by the lateral inclination of the road _surface) φ rb_e, lateral velocity estimate v _e, estimating the yaw rate estimated value r _e]. 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 yaw moment disturbance estimated value (hereinafter also simply referred to as a moment disturbance estimated value) φ _{mo_e} , a lateral gradient disturbance estimated value φ _{rb_e} , a lateral velocity estimated value v _e , estimated by the observer 32. a yaw rate estimated value r _e, the detected front-wheel steering angular speed omega _{f_s} front wheel steering angular velocity detecting means 21, the front steering and front wheel steering angle [delta] _{f_s} detected by the angular velocity detecting means 21, the vehicle speed detected by the vehicle speed detecting means 25 Based on V, 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 rudder angular velocity ω _{f_s} by the gain k _ω to obtain the front wheel rudder angular velocity corresponding correction amount (= k _ω ω _{f_s} ), and the front wheel rudder angle δ _{f_s} by the gain Kδ. the 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 _r a yaw rate estimated value r _e the over yaw rate corresponding correction amount (= k _{r r e),} each calculated basic by these correction amounts of added value _{T m_fb (= k ω ω f_s} + k δ ω f_s + k v v e + k r r e) The assist torque T _{m_base} is feedback corrected.

The moment disturbance estimated value φ _{mo_e} is multiplied by the gain k _{Φ_mo} to calculate a lateral disturbance corresponding correction amount T _{m_mo} (= k _{Φ_mo} φ _{mo_e} ), and the basic assist torque T _{m_base} is feedforward corrected using the correction amount T _{m_mo.} . As shown in FIG. 1, a lateral gradient disturbance corresponding correction amount T _{m_rb} (= _{kΦ_rb} φ _{rb_e} ) is calculated by multiplying the lateral gradient disturbance estimated value φ _{rb_e} by a gain k _{Φ_rb} (= small value). While the basic assist torque T _{M_base} may be feedforward correction by the amount, basically, in accordance with only the moment the disturbance estimated value phi _{Mo_e,} as the influence of the lateral disturbance is eliminated, the basic assist torque T _{M_base} It is important to correct feedforward.

Therefore, the control system is configured to suppress only the influence of the side wind disturbance among the side gradient disturbance and the side wind disturbance (also referred to as a side force disturbance) separated by the observer 32 estimation.
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.

When the estimation by the observer 32 is further described, the relationship of each variable related to the DC motor 11 can be modeled in a control block as shown in FIG.
The parameters in FIGS. 1 and 2 are shown in Table 1 below.

  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 l ₁₁ , l ₁₂ , l ₂₁ , l ₂₂ , l _{31 are determined.} , L ₃₂ , l ₄₁ , and l ₄₂ can be set to appropriate values by mathematical calculation in consideration of the frequency characteristics of the motor.
Therefore, in the observer 32, each of the state quantities of the front wheel steering angle δ _{f — s} , the yaw rate r _s , the lateral acceleration G _{y — s} , and the vehicle speed V is used as input amounts, and the lateral velocity estimated value v _e , the yaw rate estimated value r _e, and the moment disturbance estimated value φ Each state quantity of _{mo_e} and lateral gradient disturbance estimated value φ _{rb_e} can be estimated.

Here, the observer 32 for estimating the side gradient disturbance and the side wind 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 (T _h = 0).
(D) Since a lateral force disturbance other than the gradient generated in the vehicle is not assumed, the lateral force disturbance other than the gradient is included in the moment disturbance estimated value.

  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.

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 driver torque _Th and the steering wheel angle α, which are sensor values.

  When the previous equation (2) is modified, the following equation (4) is obtained.

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 follows.

Here, v is the lateral velocity of the vehicle, γ is the yaw rate of the vehicle, and φ is a lateral disturbance element. The system 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.
These moment disturbance estimated values φ _{mo — e} and lateral gradient disturbance φ _rb are given as external inputs to equations (5) and (6), 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. A lateral acceleration sensor value, which is an output signal to be measured, is expressed by a vehicle state quantity and a lateral gradient disturbance φ _rb as shown in the following equation, but does not include a moment disturbance φ _mo . 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 (7) on the flat road s having no right and left gradients, but is a disturbance φ _rb having a lateral gradient. Is included, equation (8) is obtained.

The above equations (7) and (8) indicate that the two lateral disturbances φ _mo and φ _rb can be separated, and the equations (5), (6), and (8) are arranged as follows: The equation of state is obtained.

Here, in order to design an observer that simultaneously estimates the unknown state quantity v and the lateral disturbances φ _mo and φ _rb , the two lateral disturbances φ _mo and φ _rb are expanded as state quantities as shown in the following equation. Define the model.

In the above equations (11) and (12), the rank (rank [C CA... CA ⁿ⁻¹ ] ^T ) of the coefficient matrices A and C (lower equations) of v, γ, φ _mo and φ _rb is the number of states. Since (state type) n is satisfied, it is observable, and the unknown state quantity v and unknown disturbances φ _mo and φ _rb can be estimated by the observer. Here, v, γ, φ _mo , and φ _rb are estimation results, and the following L is an estimation gain matrix.

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 disturbances 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).

  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 equation.

Here, [k _ω , k _δ , k _v , k _γ ] is a state feedback gain, which is 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 _mo and φ _rb are estimated from the disturbance observer. On the other hand, the disturbance suppression feedforward loop is intended to reduce the influence of yaw motion generated in the vehicle due to crosswinds, etc. Specifically, the steady value of the yaw rate generated by the moment disturbance estimated value φ _{mo_e} is set to zero. Determine the feed forward gain. When determining this feedforward gain k _ff , it is assumed that φ _rb = 0 in equation (14).

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

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

Here, δ _fss , v _ss and γ _ss are steady values of δ _f , v and γ with respect to φ _mo . Therefore, the following equation that directly solves this equation is obtained.

Here, since the control amount has a steady value of 0, γ _ss = 0 can be set. Therefore,

Expression (21) can be modified as the following expression (21 ′), and the feedforward gain K _ff (= _{KΦ_mo} ) is obtained from the following expression (22).

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 r e)} the basic assist torque T _{M_base} well as the feedback correction by _{T m_fb (= k ω ω f_s} + k δ ω f_s + k v v e + k r r e), basic by lateral disturbance corresponding correction amount _{T m_mo (= k Φ_mo φ mo_e} ) since the assist torque T _{M_base} feed forward correction, by controlling the steering assist torque of the electric motor so as to suppress the transverse gradient disturbance lateral disturbance to remove (crosswind disturbance) phi _mo among the lateral disturbance Since obtaining, while ensuring smooth running performance of the curved road, by suppressing the influence of the crosswind disturbance to the steering, it is possible to improve the active safety.

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, the gains _{k ω, k δ, k v} , k r, for k _{Fai_mo,} as it is possible to improve the stability and steering feeling of the system, it is important to appropriately set according to the vehicle speed .

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. 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 Estimation means (observer)
32 Basic control amount setting unit (Electric power steering control calculation unit)
33 Correction means (disturbance suppression correction means)
34 Steering assist correction amount calculation unit (disturbance suppression control calculation unit)
35 Calculation unit

Claims (5)

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 is separated into a yaw moment disturbance φ _mo trying to rotate the vehicle and a lateral gradient disturbance φ _rb acting on the vehicle due to the lateral inclination of the traveling road surface. And estimating means for estimating
The control means is provided with a correction means for correcting the steering assist torque applied by the actuator so as to mainly suppress the yaw moment disturbance φ _mo of the lateral disturbance of the vehicle based on the estimation result by the estimation means. A power steering device for a vehicle. 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 yaw moment disturbance φ _mo and the lateral gradient disturbance φ _rb estimated by the estimation means, and the first correction torque and the second correction torque are calculated. The power steering apparatus for a vehicle according to claim 1, wherein the steering assist torque is corrected based on the steering assist 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 power steering apparatus according to claim 1 or 2, further comprising an observer for estimating the yaw moment disturbance _φmo and the lateral gradient disturbance _φrb , which are state quantities, from the quantity. 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, and the yaw moment disturbance φ _mo described above. 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 steering is performed based on the first correction torque and the second correction torque. The vehicle power steering apparatus according to any one of claims 1 to 3, wherein the assist torque is corrected. 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 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. From the state quantities of γ and the lateral acceleration G _y , the state quantities of the yaw moment disturbance φ _mo trying to rotate the vehicle and the side gradient disturbance φ _rb acting on the vehicle due to the lateral inclination of the traveling road surface are estimated. A vehicle disturbance estimation, comprising: an observer for estimating the lateral disturbance of the vehicle by separating it into the yaw moment disturbance φ _mo and the lateral gradient disturbance φ _rb apparatus.

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