JP2006168649A - Power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power steering device capable of realizing accurate determination of an input direction of steering torque and the optimum steering force assist according to the input direction of the steering torque. <P>SOLUTION: The power steering device is provided with an input determination part 13h for determining whether detected input torque is an input from a steering side or an input from a road surface side based on a steering angular velocity θ<SB>h</SB>' and a pinion angular velocity θ<SB>p</SB>'; and a frequency characteristic correction means (input determination part 13h, personal input correction part 13i, road surface input correction part 13j and target steering torque correction part 13k) for correcting the frequency characteristic of the assist torque such that gain of the assist torque is enhanced in a frequency area of steering of a driver when it is determined that the input torque is the input from the steering side and gain of the assist torque is reduced in the frequency area of disturbance input from the road surface when it is determined that the input torque is the input from the road surface side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention belongs to the technical field of a power steering apparatus that assists the steering of a driver by an assist actuator such as a motor connected to a steering system of a vehicle.

The conventional power steering apparatus is configured to assist the steering torque applied to the steering shaft with the output torque of the motor. In other words, the output torque of the motor is increased or decreased by varying the amplification degree of the detection signal of the steering torque applied by the driver to the steering shaft in accordance with the detection signal such as the vehicle speed or the road condition, thereby obtaining a desired steering torque. Yes (see, for example, Patent Document 1).
Japanese Patent Publication No. 50-33584

  However, in the above-described conventional power steering apparatus, even when there is a disturbance input from the road surface to the steering shaft, the assist torque is generated according to the detected input torque. There is a problem in that assist torque is generated and steering feeling is deteriorated.

  The present invention has been made paying attention to the above-mentioned problems, and its purpose is to accurately determine the steering torque input direction and to realize an optimum steering force assist according to the steering torque input direction. The object is to provide a steering device.

In order to achieve the above object, the present invention provides:
An input torque detecting means for detecting an input torque to a steering shaft connecting the steering wheel and the steering mechanism;
An assist actuator that outputs an assist torque for assisting the input torque to the steering mechanism;
Assist control means for driving and controlling the assist actuator in accordance with the input torque;
In a power steering apparatus having
A steering-side steering state quantity detecting means for detecting a steering-state quantity on the steering wheel side relative to the assist actuator;
Steering wheel side steering state amount detecting means for detecting a steering state amount on the steered wheel side with respect to the assist actuator;
An input determination means for determining whether the detected input torque is an input from the handle side or an input from the road surface side based on the steering wheel side steering state amount and the steered wheel side steering state amount;
When it is determined that the input torque is input from the steering wheel side, the assist torque gain is increased in a predetermined driver steering frequency region, and the input torque is determined to be input from the road surface side. A frequency characteristic correcting means for correcting the frequency characteristic of the assist torque so as to reduce the gain of the assist torque in a frequency region of disturbance input from a preset road surface when
It is characterized by providing.

  In the present invention, the input direction of the steering torque is determined on the basis of the two steering state quantities on the steering wheel side and the steering wheel side with the assist actuator interposed therebetween, so that the input torque is not affected by the friction or inertia of the assist actuator. It is possible to accurately determine whether the vehicle is on the steering wheel side or the road surface side.

  When it is determined that the input torque is input from the steering wheel side, the assist torque is increased in the steering frequency range to increase the steering feeling, and the input torque is input from the steering wheel side. If it is determined, the assist torque gain is reduced in the frequency range of disturbance input from the road surface to reduce vehicle wobbling and driver steering burden during the disturbance action.

  Therefore, in the power steering device of the present invention, it is possible to realize accurate determination of the input direction of the steering torque and optimum steering force assist according to the input direction of the steering torque.

  Hereinafter, the best mode for carrying out the power steering apparatus of the present invention will be described based on Examples 1 to 9.

First, the configuration will be described.
FIG. 1 is a diagram illustrating a configuration of the electric power steering apparatus according to the first embodiment.

  A steering wheel 1 for steering operation by the driver is provided at an upper end portion of a steering shaft (steering shaft) 2, and a pinion 5 is provided at a lower end portion of the steering shaft 2. The steering shaft 2 includes, in order from the handle 1 side, a handle angle sensor (handle-side steering state amount detection means) 3, a torque sensor (input torque detection means) 9, a motor (assist actuator) 11, and a pinion angle sensor (steering). Wheel side steering state amount detection means) 4 is provided.

  The handle angle sensor 3 detects the rotation angle of the upper end portion of the steering shaft 2, that is, the handle 1 side. The torque sensor 9 detects the input torque to the steering shaft 2. The pinion angle sensor 4 detects the rotation angle of the lower end portion of the steering shaft 2, that is, the pinion 5.

  The pinion 5 and a rack (not shown) formed on the rack shaft 6 constitute a rack and pinion type steering mechanism. The rack shaft 6 is slidably provided in the vehicle width direction, and front wheels (steering wheels) 8 and 8 are connected to both ends of the rack shaft 6 via tie rods 7 and 7. That is, the rack shaft 6 slides left and right according to the steering amount of the driver input to the handle 1, and the front wheels 8, 8 are steered.

  The motor 11 outputs the generated torque to the steering shaft 2 via the speed reducer 10 that converts the rotational torque of the steering shaft 2 to assist the driver's steering force. The motor current supplied to the motor 11 is controlled by a controller (assist control means) 12.

  In addition to the steering wheel angle from the steering wheel angle sensor 3, the steering torque from the torque sensor 9, and the pinion angle from the pinion angle sensor 4, the controller 12 includes a yaw rate from the yaw rate sensor 15 and a vehicle speed sensor (vehicle speed detection means). ) The vehicle speed from 16 is input. The controller 12 calculates the drive current of the motor 11 based on the input from each sensor, and supplies the calculated drive current to the motor 11. Power supplied to the motor 11 is provided by a battery 14.

The controller 12 includes an angular velocity calculation unit 13A, a comparison unit 13B, and a steering torque calculation unit 13C.
The angular velocity calculation unit 13A calculates a steering wheel angular velocity from the steering wheel angle and calculates a pinion angular velocity from the pinion angle.

  The comparison unit 13B compares the steering wheel angular velocity calculated by the angular velocity calculation unit 13A with the pinion angular velocity, and determines whether the input torque is input from the driver or input from the road surface. The steering torque calculation unit 13C calculates the auxiliary steering torque, that is, the assist torque to be output from the motor 11 based on the result of the comparison unit 13B, and calculates the drive current of the motor 11 according to the auxiliary steering torque.

FIG. 2 is a system block diagram of the controller 12 according to the first embodiment.
The steering torque detector 13 a detects the steering torque T _input from the detection value of the torque sensor 9. In the steering wheel angle detecting unit 13b, it detects a steering wheel angle theta _h of the vehicle from the detected value of the steering wheel angle sensor 3. The pinion angle detection unit 13 c detects the pinion angle θ _{p of the} vehicle from the detection value of the pinion angle sensor 4.

The target steering torque calculation unit 13d, based on the steering torque T _{input The} and the sensor values detected by the steering torque detecting unit 13a (yaw rate sensor 15, a vehicle speed sensor 16), determines a target assist steering torque T _i. At this time, the target auxiliary steering torque _Ti is calculated by adapting the detection result from the torque sensor 9 to an experimentally obtained map or equation.

As the characteristic of the target auxiliary steering torque T _i , for example, the target auxiliary target auxiliary steering torque T _i is increased so that the steering wheel 1 is lightly cut at stationary or extremely low speeds, and the steering wheel 1 is heavy and heavy at high speeds. Thus, the target auxiliary steering torque _Ti is reduced.

The steering wheel angular velocity calculator 13e calculates a steering wheel angular velocity θ _h ′ based on the steering wheel angle detected by the steering wheel angle detector 13b. The pinion angular velocity calculation unit 13f calculates the pinion angular velocity θ _p ′ based on the pinion angle detected by the pinion angle detection unit 13c. The steering wheel angular velocity calculator 13e and the pinion angular velocity calculator 13f constitute the angular velocity calculator 13A shown in FIG.

  The comparison calculation unit (steering state amount change speed comparison calculation means) 13g compares the steering wheel angular velocity calculated by the steering wheel angular velocity calculation unit 13e with the pinion angular velocity calculated by the pinion angular velocity calculation unit 13f.

  The input determination unit (input determination unit) 13h determines whether the input torque is input from a human being or road input based on the comparison result of the comparison calculation unit 13g. At this time, if the steering wheel angular velocity is larger than the pinion angular velocity, it is determined that the input is from a human, and if the steering wheel angular velocity is smaller than the pinion angular velocity, it is determined that the input is from the road surface. When the steering wheel angular velocity is equal to the pinion angular velocity, the input direction cannot be determined. The comparison operation unit 13g and the input determination unit 13h constitute the comparison unit 13B illustrated in FIG.

The human input correction unit 13i determines the frequency characteristic of the steering angle input filter that corrects human input based on the determination result of the input determination unit 13h. The road surface input correction unit 13j determines the frequency characteristic of the steering angle input filter that corrects the road surface input based on the determination result of the input determination unit 13h. Frequency characteristics of the filter, for example, calculates the steering wheel angle frequency f _h from the steering wheel angle theta _h, calculate a pinion angular frequency f _p than the pinion angle theta _p, is determined based on these frequencies f _h, the f _p .

The target steering torque correction unit (frequency characteristic correcting means) 13k, with respect to the target assist steering torque T _i calculated based on the steering torque T _{input The,} human input correction unit 13i and the filter by the filter determined by the road surface input correction unit 13j Processing is performed to calculate the auxiliary steering torque T _M.

  The target steering torque calculation unit 13d and the target steering torque correction unit 13k constitute the steering torque calculation unit 13C illustrated in FIG. The input determination unit 13h, the human input correction unit 13i, the road surface input correction unit 13j, and the target steering torque correction unit 13k constitute a frequency characteristic correction unit.

The control current calculation unit 13 m converts the auxiliary steering torque T _M determined by the target steering torque correction unit 13 k into a control current amount I _M that flows through the motor 11 and outputs the converted control current I _M to the motor 11.

Next, the operation will be described.
[Assist control processing]
FIG. 3 is a flowchart showing the flow of assist control processing executed by the controller 12 of the first embodiment, and each step will be described below.

In step S1, the detected value T _input of the torque sensor 9, the value θ _h of the steering wheel angle sensor 3, the value θ _p of the pinion angle sensor 4, the value γ of the yaw rate sensor 15, and the value V of the vehicle speed sensor 16 are detected. And proceeds to step S2.

In step S2, a target auxiliary steering torque _Ti is determined from the value _Tinput of the torque sensor 9 read in step S1, and the process proceeds to step S3.

In step S3, a steering wheel angular velocity θ _h ′ and a pinion angular velocity θ _p ′ are calculated based on the value θ _h of the steering wheel angle sensor 3 and the value θ _p of the pinion angle sensor 4 read in step S1, and the process proceeds to step S4. Transition.

In step S4, it is determined whether or not | θ _h '|> | θ _p ' | from the steering wheel angular velocity θ _h 'and the pinion angular velocity θ _p ' calculated in step S3. If YES, the process proceeds to step S5. If NO, the process proceeds to step S6.

  In step S5, it is determined that the input is human, and the process proceeds to step S7.

  In step S6, it is determined that the road surface (disturbance) is input, and the process proceeds to step S7.

In step S7, on the basis of the pinion angle frequency f _p obtained from the determination result and the handle angular frequency obtained from the steering wheel angle theta _h f _h and pinion angle theta _p in step S5 or step S6, to determine the filter characteristics. Subsequently, the target assist steering torque T _i to filter calculates the assist steering torque T _M, the process proceeds to step S8.

Here, filter processing of the target assist steering torque T _i, in addition to the filter based on the steering angle frequency f _h and the pinion angular frequency f _p, and a filter in accordance with the road surface friction coefficient mu, a filter in accordance with the vehicle speed V, the This is performed using a filter corresponding to the steering state. The road surface friction coefficient calculation method may be an arbitrary method such as a method of estimating from the difference between the wheel speed and the vehicle body speed or a method of referring to road infrastructure information (corresponding to road surface friction coefficient detection means). .

In step S8, the control current amount I _M output from the motor 11 is determined from the auxiliary steering torque T _M corrected in step S7, and the process proceeds to step S9.

In step S9, the control current amount I _M determined in step S8 is supplied to the motor 11 to cause the motor 11 to output assist torque, and the process proceeds to return.

Next, a method for determining the frequency characteristics of the filter in step S7 will be described.
[Filter processing according to torque input direction]
If it is determined in step S5 that the input is human, the filter shown in FIG. 4 is used. If it is determined in step S6 that the road is input, the filter shown in FIG. 5 is used.

Gain1 filter of Figure 4 is set to a frequency characteristic as increasing the gain near the steering wheel angle frequency f _h, Gain2 filter of Figure 5 is set to a frequency characteristic as lower the gain in the vicinity of the pinion angular frequency f _p Has been. This improves the steering sensitivity at the time of steering input and ensures vehicle stability by suppressing disturbance input.

  Here, when it is determined that the input is human, the filter shown in FIG. 6 may be used instead of the filter shown in FIG. 4, and when the input is determined as the road surface input, the filter shown in FIG. 7 may be used instead of the filter shown in FIG. .

  The gain Gain3 of the filter in FIG. 6 is set to a frequency characteristic that increases the gain of the high frequency component, and the Gain 4 of the filter in FIG. 7 is set to a frequency characteristic that decreases the gain of the low frequency component. As a result, the human steering compensation amount at the time of high-speed turning is increased to improve the steering feeling, and the vehicle stability is ensured by suppressing disturbance input.

[Filter processing according to road friction coefficient]
In step S7, if the road surface friction coefficient is smaller than a specific low μ road threshold value μ ₀ , the filter shown in FIG. 8 is used. Gain 5 of this filter is set to a frequency characteristic that increases the gain of the low frequency component and decreases the gain of the high frequency component. This ensures the stability of the vehicle while traveling on a low μ road.

[Filter processing when the steering wheel angular velocity and pinion angular velocity are both minimum values]
In step S7, when both the steering wheel angular velocity θ _h ′ and the pinion angular velocity θ _p ′ are minimal values and the deviation between the two is slight, the possibility of corrective steering is high, so the filter shown in FIG. 9 is used. Gain 6 of this filter is set to a frequency characteristic that increases the gain of the low frequency component. As a result, the driver's steering burden on the correction steering is reduced, and an improvement in steering feeling is ensured.

[Filter processing according to vehicle speed]
If it is determined in step S7 that the input is human, a filter process corresponding to the vehicle speed V is performed. For example, the filter shown in FIG. 10 is used during low-speed traveling where 0 ≦ V ≦ 10 (low vehicle speed threshold) [km / h]. Gain7 of this filter is set to a frequency characteristic as increasing the gain near the steering wheel angle frequency f _h.

When traveling at a high speed where 80 (high vehicle speed threshold) <V [km / h], a filter as shown in FIG. 11 is used. Gain 8 of this filter is set to a frequency characteristic that increases the gain of a low frequency component having a handle angular frequency f _h or less.

The filter shown in FIG. 12 is used during medium speed traveling where 10 <V ≦ 80 [km / h]. The gain 9 of this filter is basically set to a frequency characteristic that increases the gain in the vicinity of the steering wheel angular frequency f _h . However, the higher the vehicle speed V, the closer to the frequency characteristic during high speed driving shown in FIG. Is set to

  Here, the steering wheel steering frequency when operating a human vehicle is generally said to be 0 [Hz] to 10 [Hz], and particularly when parking or traveling at a low speed, steering at a large steering angle is often performed. High-speed steering is required. Therefore, during extremely low speed to low speed traveling, for example, by increasing the gain of 2 [Hz] or more and 10 [Hz] or less, the driver's steering operation burden is reduced, and the steering feeling is improved.

  Further, steering at high speed is often fine steering mainly for correcting the direction of the vehicle, and the steering angle is small and low-speed steering is performed. Therefore, when driving at high speed, the gain of 0 [Hz] to 1 [Hz] is increased to improve the stability of the vehicle.

  Further, when the vehicle travels at medium speed, the frequency characteristics at the time of high-speed traveling are increased as the vehicle speed V increases, thereby achieving both improvement in the driver's steering feeling and improvement in vehicle stability.

[Filter processing according to the steered state]
When the steering angle is maintained at a moderate steering angle (10 [deg] to 40 [deg]) for a certain period of time or longer, for example, 15 [deg] for 2 [s] or longer, The case of rudder can be considered. For this reason, in step S7, the load shown in FIG. 13 is used to increase the gain of extremely low frequency including 0 [Hz], thereby reducing the steering load during turning or the like and improving the stability of the vehicle.

Here, the steering holding state is detected based on the steering wheel angle θ _h and the steering wheel angular velocity θ _h ′, which are the outputs of the steering wheel angle sensor 3. Specifically, when the steering wheel angle θ _h is any angle between 10 [deg] and 40 [deg] and the steering wheel angular velocity θ _h ′ is less than a predetermined value for 2 [s] or longer, the steering is maintained. (Corresponding to the steering holding detection means).

[Filter processing when the steering wheel angular velocity and pinion angular velocity are almost the same]
When the values of the steering wheel angular velocity θ _h and the pinion angular velocity θ _p are substantially the same and it is difficult to determine whether the input is human input or road input, the filter shown in FIG. 14 is used in step S7. Gain 11 of this filter is set to a frequency characteristic that increases the gain of a low frequency component having a handle angular frequency f _h or less.

By correcting the target assist steering torque T _i by these filtering, it is possible to realize improvement of steering feeling, the stabilization of the reduction and the vehicle steering load. However, any of the above logics is performed within a range that enhances the effect of improving the steering feeling and the normal function of the electric power steering is not lost.

[Incorrect determination of steering torque input direction in the prior art]
In the power steering apparatus, in addition to the magnitude of torque applied to the steering shaft, it is necessary to detect the direction of the torque. In the conventional steering torque detection logic, across the torque sensor in the steering shaft input side compares the rotation angle theta _p of the rotation angle theta _h and the output side of the (handle side) (pinion side) (FIG. 15 (a)) Then, it is determined that torque is applied in the direction in which the input side is leading (FIG. 15 (b)).

  On the other hand, when steering a running vehicle, not only the regular input torque (steering torque) applied from the steering wheel side in response to the steering operation, but also the road surface reaction force applied to the steering wheel is input torque from the steering wheel side (hereinafter referred to as reverse input). Called the torque).

  However, the reverse input torque as described above is applied in a state where the pinion side precedes the steering torque which is a normal input. As a result, in the above-described steering torque detection logic, it is as if the steering torque in the same direction as the direction of bias of the steered wheels due to the road surface reaction force that is the cause of the reverse input torque is the input torque direction determination. judge. As a result, when the steering assist motor is driven in response to this torque detection, the driving force of the motor is applied to the steering mechanism in the same direction as the reverse input torque. Torque to be transmitted is transmitted, and the steering feeling may be deteriorated.

  That is, it is difficult for the conventional technology to determine whether the input torque is due to the driver or the road surface reaction force. In particular, the auxiliary steering is appropriately performed when a disturbance depending on the road surface state or the traveling state is input. There was a problem that not.

  Therefore, the rotation angle of the steering shaft connecting the steering wheel and the steering mechanism is detected at different positions in the axial length direction, and the torque applied to the steering wheel is calculated based on the detected difference in the rotation angle, and the angular velocity or angular velocity is calculated. A power steering device that includes means for determining whether the input torque is based on an input from a steering wheel side or an input from a steered wheel side based on a relationship between accelerations, and drives and controls the motor based on the determination result Proposals have been made.

  However, in the configuration of the power steering device described above, since the input from the road surface is transmitted to the angle detector through the motor, it is not possible to detect the friction and inertia components due to the influence of the motor friction and inertia. Therefore, there is a problem that the input (disturbance) from the road surface cannot be accurately detected.

[Determination of torque input direction based on steering wheel angular velocity and pinion angular velocity]
On the other hand, in the electric power steering apparatus according to the first embodiment, the steering angle θ _h and the pinion are detected by two angle sensors (the steering angle sensor 3 and the pinion angle sensor 4) arranged at different positions on the steering shaft 2 with the motor 11 interposed therebetween. The angle θ _p is detected. Then, by comparing the steering wheel angular velocity θ _h ′ with the pinion angular velocity θ _p ′ from the steering wheel angle θ _h and the pinion angle θ _p , the torque applied to the steering shaft 2 is input from the steering wheel side or the input from the wheel side. Determine whether.

As shown in FIG. 16, in the case of an input on the steering wheel side (human input), the generation of the pinion angle θ _p is delayed with respect to the steering wheel angle θ _h due to a delay specific to the steering system. _h ′ rises quickly with respect to the pinion angular velocity θ _p ′. On the other hand, in the case of steering wheel side input (road surface input), the generation of the steering wheel angle θ _h is delayed with respect to the pinion angle θ _p due to a delay specific to the steering system. At this time, the pinion angular velocity θ _p ′ is , Stand up quickly with respect to the steering wheel angular velocity θ _h '.

That is, in the first embodiment, the absolute value | θ _h '| of the steering wheel angular velocity is compared with the absolute value | θ _p ' | of the pinion angular velocity, and when | θ _h '|> | θ _p ' | If it is determined that the input is from the steering wheel side and | θ _h '| <| θ _p ' |, the input from the steered wheel side is determined to be affected by the friction, inertia, and the like of the motor 11. Thus, the torque input direction can be accurately determined.

[Assist action according to torque input direction]
In the first embodiment, when the steering torque T _input is an input from the steering wheel side, the motor 11 is driven and controlled as a characteristic that increases the gain near the steering wheel angular frequency f _h (gain near the human steering frequency). Thus, the steering feeling and the steering sensitivity at the time of steering input can be improved.

Also, when the steering torque T _{input The} is an input from the road surface, by controlling the driving of the motor 11 as a characteristic to decrease the pinion angle frequency f _p vicinity of the gain (gain near the road surface input frequency) disturbance effects At the time, specifically, it is possible to reduce the vehicle wobble and the driver's steering load on a cant road or a road surface having a bad road surface condition.

  Further, in the first embodiment, since the frequency characteristics of the assist torque are changed not only in the torque input direction but also in the driving state such as the road surface friction coefficient μ, the vehicle speed, and the steering state, the steering feeling is improved in various driving scenes. In addition, it is possible to reduce the steering load and stabilize the vehicle.

Next, the effect will be described.
In the electric power steering apparatus according to the first embodiment, the following effects can be obtained.

(1) A torque sensor 9 that detects input torque to the steering shaft 2 that connects the steering wheel 1 and the steering mechanism, a motor 11 that outputs assist torque to assist the input torque to the steering mechanism, and the input torque In a power steering apparatus having a controller 12 for driving and controlling the motor 11, a steering-side steering state amount detection means (a steering wheel angle sensor 3) that detects a steering state amount (a steering wheel angle θ _h ) closer to the steering wheel than the motor 11. Steering wheel side steering state amount detecting means (pinion angle sensor 4) for detecting the steering state amount (pinion angle θ _p ) on the steered wheel side relative to the motor 11, the steering wheel side steering state amount and the steered wheel side Based on the steering state quantity, an input determination unit 13h that determines whether the detected input torque is input from the steering wheel side or input from the road surface side; When it is determined that the input from Le side, increasing the gain of the assist torque in the frequency f _h region of a steering of a preset driver (see FIG. 4), when the input torque is input from the road surface when it is determined to lower the gain of the assist torque in the frequency f _p region of the disturbance inputs from the preset road (see FIG. 5) as described above, the frequency characteristic correcting means for correcting the frequency characteristic of the assist torque (input determination 13h, a human input correction unit 13i, a road surface input correction unit 13j, and a target steering torque correction unit 13k), so that an accurate determination of the steering torque input direction and an optimum steering according to the steering torque input direction are provided. Force assist can be realized.

  (2) When it is determined that the input torque is input from the steering wheel side, the frequency characteristic correcting means increases the gain of the high frequency component exceeding the predetermined frequency of the assist torque (see FIG. 6), and the input torque is increased on the road surface side. When it is determined that the input is from the engine, the gain of the low frequency component that is equal to or lower than the predetermined frequency of the assist torque is decreased (see FIG. 7). The vehicle stability can be ensured by improving disturbance and suppressing disturbance input.

  (3) A vehicle speed sensor 16 for detecting the vehicle speed V is provided, and the frequency characteristic correction means determines the frequency characteristic of the assist torque according to the change in the vehicle speed V when it is determined that the input torque is input from the steering wheel side. Since the frequency region to be corrected is changed, the optimum steering force assist can be realized according to the vehicle speed V.

(4) The frequency characteristic correction means increases the assist torque gain in the driver's steering frequency f _h region during low speed driving when the vehicle speed V is equal to or lower than a predetermined low vehicle speed threshold (10 [km / h]). Therefore, the driver's handle operation burden can be reduced and the steering feeling can be improved at the time of parking or low speed traveling where high speed steering is required.

(5) The frequency characteristic correction means is a low frequency component of assist torque when the vehicle speed V exceeds a predetermined high vehicle speed threshold (80 [km / h]) and is below the driver's steering frequency f _h region. (See FIG. 11), it is possible to improve the stability of the vehicle at the time of high-speed traveling with a lot of minute correction steering.

(6) When the vehicle speed V is in the vehicle speed range between the low vehicle speed threshold (10 [km / h]) and the high vehicle speed threshold (80 [km / h]), the frequency characteristic correcting means The higher the value, the lower the high frequency component gain of the assist torque and the low frequency component gain in the driver's steering frequency f _h region (see FIG. 12), thereby improving the driver's steering feeling and vehicle stability. It is possible to achieve both improvement in performance.

  (7) Provided with a steering holding means for detecting a steering holding state in which the handle 1 is held at a predetermined angle (10 [deg] to 40 [deg]) for a certain time (about 2 [s]), the frequency characteristic correcting means is When the steering state is detected, the gain of the extremely low frequency component of the assist torque is increased (see FIG. 13), so that the burden of steering can be reduced during turning and the stability of the vehicle can be improved. .

(8) A road surface friction coefficient detecting means for detecting the road surface friction coefficient μ of the traveling road is provided, and the frequency characteristic correcting means is configured such that when the detected road surface friction coefficient μ is smaller than a predetermined low μ road threshold value μ ₀ , Since the gain of the low frequency component of the assist torque is increased and the gain of the high frequency component is decreased (see FIG. 8), it is possible to ensure the stability of the vehicle while traveling on a low μ road.

(9) Steering wheel side steering state quantity changing speed (steering wheel side steering state quantity changing speed (steering wheel angular speed θ _h ')) and steering wheel side steering state quantity changing speed which is the changing speed of the steering wheel side steering state quantity And a comparison calculation unit 13g that compares (pinion angular velocity θ _p ′) with the input determination unit 13h when the steering wheel side steering state amount change speed is larger than the steering wheel side steering state amount change speed. Since it is determined that the input is from the side, the input direction of the steering torque can be accurately determined using the two angle sensors without being affected by the friction and inertia of the motor 11 and the speed reducer 10.

(10) The input determination unit 13h determines that the input direction cannot be determined when the steering wheel side steering state amount change speed is equal to the steered wheel side steering state amount change speed, and the frequency characteristic correction unit determines that the input direction determination is impossible. Since the gain of the low frequency component of the assist torque is increased in the region below the steering frequency f _h of the driver (see FIG. 14), the stability of the vehicle can be improved when a slight correction steering is performed. .

  (11) The input determination unit 13h determines that the steering is corrected when the steering wheel side steering state amount change speed and the steered wheel side steering state amount change speed are both minimum values and the deviation between the two is slight, and the frequency characteristics are determined. When it is determined that the correction steering is performed, the correction means increases the gain of the low frequency component of the assist torque (see FIG. 9), so that the driver's steering burden for the correction steering can be reduced, and an improvement in steering feeling can be secured. .

(12) The steering wheel side steering state quantity detection means is a steering wheel angle sensor 3 that detects the steering wheel angle θ _h that is the rotation angle of the steering shaft 2 on the steering wheel side relative to the motor 11, and the steering wheel side steering state quantity detection means. Is a pinion angle sensor 4 that detects the pinion angle θ _p that is the rotation angle of the steering shaft 2 on the steered wheel side relative to the motor 11, so that the two are not affected by the friction or inertia of the motor 11. An angle sensor can be used to accurately determine the torque input direction.

  In the second embodiment, the torque sensor is not provided, and the input torque to the steering shaft is estimated from the steering wheel angle and the pinion angle.

FIG. 17 is a system block diagram of the controller 12a according to the second embodiment. In the second embodiment, the input torque T _input is estimated based on the difference between the handle angle θ _h and the pinion angle θ _p instead of the torque sensor. A torque estimation unit 13n is provided. The target steering torque calculation unit 13d, based on the estimated input torque T _{input The,} determines a target assist steering torque T _i.
Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

Next, the operation will be described.
[Assist control processing]
FIG. 18 is a flowchart showing the flow of the assist control process executed by the controller 12a according to the second embodiment. Each step will be described below. Steps S14 to S20 are the same steps as steps S3 to S9 in FIG.

In step S11, it reads the value theta _h of the steering wheel angle sensor 3, the value theta _p of the pinion angle sensor 4, and the value γ of the yaw rate sensor 15, and a value V of the vehicle speed sensor 16, the process proceeds to step S12.

In step S12, the input torque T _input is estimated from the deviation | θ _h −θ _p | between the steering wheel angle θ _h and the pinion angle θ _p read in step S1, and the process proceeds to step S13.

In step S13, a target target auxiliary steering torque _Ti is determined based on the estimation result in step S2, and the process proceeds to step S14.

[Input torque estimation function]
In the second embodiment, in order to estimate the input torque T _input based on the difference between the steering wheel angle θ _h and the pinion angle θ _p , the configuration of the first embodiment including the torque sensor 9 for detecting the input torque T _input is used. The cost can be reduced and the system can be made compact by reducing the number of parts.

Next, the effect will be described.
In the electric power steering apparatus according to the second embodiment, in addition to the effects (1) to (12) of the first embodiment, the following effects can be obtained.

(13) the input torque estimation unit 13n, based on the handle angle theta _h and the pinion angle theta _p, for estimating the input torque T _{input The,} without using the input torque detecting means, can be estimated input torque, system configuration This is advantageous.

  In Example 3, the steering system model and the vehicle model are used to estimate the pinion angle when there is no road surface (disturbance) input from the steering wheel angle, and input based on the deviation between the estimated pinion angle and the actual pinion angle It is an example which determines the direction of a torque.

Figure 19 is a system block diagram of a controller 12b of Example 3, Example 3, enter the steering wheel angle theta _h detected by the steering angle sensor 3, the estimated pinion angle in the absence of road surface input (estimated Misao A model (steering wheel side steering state amount estimating means) 13p that outputs a steering wheel side steering state amount) θ _p ^* is provided.

The model 13p includes a steering system model and a vehicle model (such as a motorcycle model or an experimentally determined map or expression), and an estimated pinion angle θ when there is no road surface (disturbance) input based on the steering wheel angle θ _h. Estimate _p ^* .

In the comparator 13q, a deviation θ _p ^* −θ _p between the estimated pinion angle θ _p ^* and the detected pinion angle θ _p is obtained and output to the input determination unit 13h ′. The input determination unit 13h ′ determines whether the input is from a human or the road surface based on θ _p ^* −θ _p .

The human input correction unit 13i ′ determines the frequency characteristic of the steering angle input filter that corrects the human input based on the determination result of the input determination unit 13h ′. The road surface input correction unit 13j ′ determines the frequency characteristic of the steering angle input filter that corrects the road surface input based on the determination result of the input determination unit 13h ′. Frequency characteristics of the filter, for example, calculates the steering wheel angle frequency f _h from the steering wheel angle theta _h, calculate a pinion angular frequency f _p than the pinion angle theta _p, is determined based on these frequencies f _h, the f _p .
Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

Next, the operation will be described.
[Assist control processing]
FIG. 20 is a flowchart showing the flow of assist control processing executed by the controller 12b of the third embodiment. Each step will be described below. Step S21, step S22, and step S28 to step S30 are steps for performing the same processing as step S1, step S2, and step S7 to step S9 in FIG.

In step S23, the estimated pinion angle θ _p ^* when there is no road surface input is estimated from the steering wheel angle θ _h read in step S21 using the steering system model and the vehicle model, and the process proceeds to step S24.

In step S24, a deviation θ _p ^* −θ _p between the estimated pinion angle θ _p ^* estimated in step S23 and the actual pinion angle θ _p is calculated, and the process proceeds to step S25.

  In step S25, it is determined whether the deviation calculated in step S24 is other than zero. If YES, the process proceeds to step S26, and if NO, the process proceeds to step S27.

  In step S26, it determines with road surface input, and transfers to step S28.

  In step S27, it is determined that there is no road surface input, that is, human input, and the process proceeds to step S28.

[Disturbance input estimation by model]
In the third embodiment, the estimated pinion angle θ _p ^* is estimated from the steering wheel angle θ _h using the model 13p, and the frequency characteristics of the assist torque are corrected according to the deviation between the estimated pinion angle θ _p ^* and the pinion angle θ _p. Therefore, compared to the first and second embodiments, disturbance detection errors other than modeling errors (detection errors by sensors, etc.) can be made zero, and the disturbance input amount can be calculated more accurately.

Next, the effect will be described.
In the electric power steering apparatus according to the third embodiment, in addition to the effects (1) to (12) of the first embodiment, the following effects can be obtained.

(14) as input steering wheel angle theta _h, equipped with a model 13p that the estimated pinion angle theta _p ^* output in the absence of disturbance inputs from the road surface by using a steering system model and the vehicle model, the input determination unit 13h ' Determines that the input torque is an input from the road surface side when a deviation occurs between the pinion angle θ _p and the estimated pinion angle θ _p ^*, and the frequency characteristic correcting means determines that the deviation θ _p ^* −θ _p Accordingly, since the frequency characteristics of the assist torque are changed, disturbance detection errors other than modeling errors (detection errors by sensors, etc.) can be made zero, and the disturbance input amount can be accurately calculated.

  In the fourth embodiment, the steering angle when there is no road surface input is estimated from the pinion angle using the steering system model and the vehicle model, and the direction of the input torque is based on the deviation between the estimated steering wheel angle and the actual steering wheel angle. It is an example which determines.

FIG. 21 is a system block diagram of the controller 12c according to the fourth embodiment. In the fourth embodiment, the pinion angle θ _h detected by the pinion angle sensor 4 is input, and the estimated handle angle (estimated handle) when there is no road surface input. Side steering state quantity) θ _h ^* is output (steering wheel side steering state quantity estimation means) 13p ′.

This model 13p ′ includes a steering system model and a vehicle model (such as a motorcycle model or an experimentally determined map or equation), and an estimated steering wheel angle θ _h when there is no road surface input based on the pinion angle θ _p. ^* Estimate.

The comparator 13q ′ obtains a deviation θ _h ^* −θ _h between the estimated handle angle θ _h ^* and the detected handle angle θ _h and outputs the deviation to the input determination unit 13h ″. Based on the deviation of θ _h ^* −θ _h , it is determined whether the input is from a human or from the road surface.

The human input correction unit 13i "determines the frequency characteristic of the steering angle input filter that corrects human input based on the determination result of the input determination unit 13h". The road surface input correction unit 13j "determines the frequency characteristic of the steering angle input filter that corrects the road surface input based on the determination result of the input determination unit 13h". Frequency characteristics of the filter, for example, calculates the steering wheel angle frequency f _h from the steering wheel angle theta _h, calculate a pinion angular frequency f _p than the pinion angle theta _p, is determined based on these frequencies f _h, the f _p .
Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

Next, the operation will be described.
[Assist control processing]
FIG. 22 is a flowchart showing the flow of assist control processing executed by the controller 12c according to the fourth embodiment. Each step will be described below. Step S31, step S32, and step S38 to step S40 are the same steps as step S1, step S2, and step S7 to step S9 in FIG.

In step S33, the steering wheel angle θ _h ^* when there is no road surface input is estimated from the pinion angle θ _p read in step S21 using the steering system model and the vehicle model, and the process proceeds to step S34.

At step S34, and calculates a deviation theta _h ^* - [theta] _h and the actual steering wheel angle theta _h and steering wheel angle theta _h estimated in step S33, the process proceeds to step S25.

  In step S35, it is determined whether or not the deviation calculated in step S34 is other than zero. If YES, the process proceeds to step S36, and if NO, the process proceeds to step S37.

  In step S36, it is determined that the road surface is input, and the process proceeds to step S38.

  In step S37, it is determined that there is no road surface input, that is, human input, and the process proceeds to step S38.

[Disturbance input estimation by model]
In the fourth embodiment, the estimated handle angle θ _h ^* is estimated from the pinion angle θ _p using the model 13p ′, and the frequency characteristics of the assist torque are corrected according to the deviation between the estimated handle angle θ _h ^* and the handle angle θ _h. Therefore, compared to the first and second embodiments, disturbance detection errors other than modeling errors (detection errors by sensors, etc.) can be made zero, and the disturbance input amount can be calculated more accurately.

Next, the effect will be described.
In the electric power steering apparatus according to the fourth embodiment, in addition to the effects (1) to (12) of the first embodiment, the following effects can be obtained.

(15) A model 13p ′ having the pinion angle θ _p as an input and using the steering system model and the vehicle model as an output and an estimated handle angle θ _h ^* in the absence of disturbance input from the road surface is provided, and an input determination unit 13h "Determines that the input torque is input from the road surface side when a deviation occurs in the steering wheel angle θ _{h and the} estimated steering wheel angle θ _h ^*, and the frequency characteristic correcting means determines that the deviation θ _h ^* −θ _h Accordingly, since the frequency characteristics of the assist torque are changed, disturbance detection errors other than modeling errors (detection errors by sensors, etc.) can be made zero, and the disturbance input amount can be accurately calculated.

  In the fifth embodiment, a steering torque sensor is provided on the steering shaft closer to the steering wheel than the motor, a pinion torque sensor is provided on the steering shaft closer to the pinion than the motor, and the input torque is compared by comparing the outputs of these two torque sensors. This is an example of determining the input direction.

  FIG. 23 is a diagram illustrating the configuration of the electric power steering apparatus according to the fifth embodiment. In the fifth embodiment, a pinion torque sensor that detects torque on the pinion side of the steering shaft 2 relative to the motor 11 is used instead of the pinion angle sensor. (Standing wheel side steering state quantity detection means) 17 differs from the first to fourth embodiments in that a steering wheel side steering state quantity detection means 17 is provided. In the fifth embodiment, the torque sensor 9 according to the first to fourth embodiments will be described as the steering wheel torque sensor (handle-side steering state amount detecting means) 9.

  That is, in the fifth embodiment, of the input torque applied to the steering shaft 2, the torque on the handle side of the motor 11, that is, the handle torque is detected by the handle torque sensor 9, and the torque on the pinion side of the motor 11, that is, the pinion torque Is detected by the pinion torque sensor 17.

FIG. 24 is a system block diagram of the controller 12d according to the fifth embodiment.
In the handle torque detecting section 13a, detects a steering wheel torque T _h from the detected value of the steering wheel torque sensor 13a. The pinion torque detector 13r detects the pinion torque T _p from the detection value of the pinion torque sensor 17.

In the torque deviation calculation unit 13s, and calculates a deviation [Delta] T _{input The} handle torque T _h and pinion torque T _p. The adder 13t adds the target auxiliary steering torque T _i and the deviation ΔT _input to calculate the pre-correction auxiliary steering torque T.

In the handle torque change amount calculation unit 13u, on the basis of the steering wheel torque T _h detected by the steering wheel torque detecting section 13a, calculates the steering wheel torque variation T _h '. The pinion torque change amount calculation unit 13v calculates a pinion torque change amount T _p ′ based on the pinion torque T _p detected by the pinion torque detection unit 13r.

The comparison calculation unit 13w compares the handle torque change amount T _h ′ calculated by the handle torque change amount calculation unit 13u with the pinion torque change amount T _p ′ calculated by the pinion torque change amount calculation unit 13v.

  The input determination unit 13x determines whether the input torque is input from a human or an input from the road surface based on the comparison result of the comparison calculation unit 13w. At this time, if the handle torque change amount> the pinion torque change amount, it is determined that the input is from a human, and if the handle torque change amount <the pinion torque change amount, it is determined that the input is from the road surface.

The human input correction unit 13y determines the frequency characteristic of the steering angle input filter that corrects human input based on the determination result of the input determination unit 13x. The road surface input correction unit 13z determines the frequency characteristic of the steering angle input filter that corrects the road surface input based on the determination result of the input determination unit 13x. Frequency characteristics of the filter, for example, to calculate the steering wheel torque frequency f _h from the handle torque T _h, to calculate the pinion torque frequency f _p than the pinion torque T _p, is determined based on these frequencies f _h, the f _p .
Other configurations are the same as those in the first embodiment, and thus description thereof is omitted.

Next, the operation will be described.
[Assist control processing]
FIG. 25 is a flowchart showing the flow of assist control processing executed by the controller 12d of the fifth embodiment. Each step will be described below. Steps S42 and S47 to S51 are the same steps as steps S2 and S5 to S9 in FIG.

In step S41, the detected value T _h of the handle torque sensor 9, the value T _p of the pinion torque sensor 17, the value γ of the yaw rate sensor 15, and the value V of the vehicle speed sensor 16 are read, and the process proceeds to step S42. .

In step S43, the calculated [Delta] T _{input The} is the absolute value of the deviation of the steering wheel torque T _h and pinion torque T _p read in step S41, the process proceeds to step S44 and step S45.

In step S44, 'calculates the pinion torque change amount T _p from the pinion torque T _p' handle torque variation T _h from the handle torque T _h detected in step S41 is calculated, and the process proceeds to step S46. It is determined whether the absolute value | T _h '| of the handle torque change amount is larger than the absolute value of the pinion torque change amount | T _p ' |. If YES, the process proceeds to step S47, and if NO, the process proceeds to step S48.

  In the fifth embodiment, the determination operation in the torque input direction based on the comparison between the steering torque change speed and the pinion torque change speed and the assist action in accordance with the torque input direction are the same as those in the first embodiment, and thus description thereof is omitted. To do.

Next, the effect will be described.
In the electric power steering apparatus according to the fifth embodiment, in addition to the effects (1) to (11) of the first embodiment, the following effects can be obtained.

  (16) The steering wheel side steering state quantity detection means is a steering wheel torque sensor 9 that detects a steering torque that is input torque to the steering shaft 2 on the steering wheel side from the motor 11, and the steering wheel side steering state quantity detection means is Since the pinion torque sensor 17 detects the pinion torque that is the input torque to the steering shaft 2 on the steered wheel side relative to the motor 11, the two torque sensors are not affected by the friction or inertia of the motor 11. Can be used to accurately determine the direction of torque input.

  In the sixth embodiment, the input torque to the steering shaft is estimated from the steering wheel torque and the pinion torque.

Figure 26 is a system block diagram of a controller 12e in Example 6, in Example 6, the input torque estimating section for estimating the input torque T _{input The} on the basis of the difference between the steering wheel torque T _h and pinion torque T _p (input Torque estimation means) 13n ′. The target steering torque calculation unit 13d, based on the estimated input torque T _{input The,} determines a target assist steering torque T _i.
Other configurations and operations are the same as those in the fifth embodiment, and thus description thereof is omitted.

[Input torque estimation function]
In the sixth embodiment, since the input torque T _input is estimated based on the difference between the handle torque _Th and the pinion torque T _p , an input detection unit for detecting the input torque T _input is not necessary, and the number of parts is reduced. Cost reduction and system downsizing can be achieved.

Next, the effect will be described.
In the electric power steering apparatus according to the sixth embodiment, the following effects can be obtained in addition to the effects (1) to (11) of the first embodiment and the effect (16) of the fifth embodiment.

(17) the input torque estimating section 13n ', based on the steering wheel torque T _h and estimated pinion torque T _p, for estimating the input torque T _{input The,} the input torque by using a means for detecting a steering state quantity Since it can be estimated, the input torque detection means is not required, which is advantageous in terms of the system configuration.

  In the seventh embodiment, the pinion torque when there is no road surface (disturbance) input is estimated from the steering torque using the steering system model and the vehicle model, and input based on the deviation between the estimated pinion torque and the actual pinion torque. It is an example which determines the direction of a torque.

Figure 27 is a system block diagram of a controller 12f Example 7 In Example 3, enter the handle torque T _h detected by the steering wheel torque sensor 9, in the absence of road surface input estimating pinion torque (estimated steering A model (steering wheel side steering state amount estimation means) 18 that outputs a steering wheel side steering state amount) T _p ^* is provided.

The model 18 includes a steering system model and the vehicle model (such as an automatic two-wheel model and experimentally obtained map or equation), based on steering wheel torque T _h, the road surface (a disturbance) when the input is not estimated pinion torque T Estimate _p ^* .

In the comparator 13q ′, a deviation T _p ^* −T _p between the estimated pinion torque T _p ^* and the detected pinion torque T _p is obtained and output to the input determination unit 13x ′. The input determination unit 13x ′ determines whether the input is from a human or the road surface based on T _p ^* −T _p .

The human input correction unit 13y ′ determines the frequency characteristic of the steering angle input filter that corrects human input based on the determination result of the input determination unit 13x ′. The road surface input correction unit 13z ′ determines the frequency characteristic of the steering angle input filter that corrects the road surface input based on the determination result of the input determination unit 13x ′.
Other configurations are the same as those in the fifth embodiment, and thus description thereof is omitted.

[Disturbance input estimation by model]
In the seventh embodiment, the estimated pinion torque T _p ^* is estimated from the handle torque T _h using the model 18, and the frequency characteristic of the assist torque is corrected according to the deviation between the estimated pinion torque T _p ^* and the pinion torque T _p. Therefore, as compared with the fifth and sixth embodiments, disturbance detection errors other than modeling errors (detection errors by sensors, etc.) can be made zero, and the disturbance input amount can be calculated more accurately.

Next, the effect will be described.
In the electric power steering apparatus according to the seventh embodiment, in addition to the effects (1) to (11) of the first embodiment and the effect (16) of the fifth embodiment, the following effects can be obtained.

(18) The input determination unit 13x ′ includes a steering torque T _h as an input and an output 18 of an estimated pinion torque T _p ^* in a state where there is no disturbance input from the road surface using the steering system model and the vehicle model. When the deviation occurs in the pinion torque T _p estimated pinion torque T _p ^* , it is determined that the input torque is an input from the road surface side, and the frequency characteristic correcting means determines according to the deviation T _p ^* −T _p. Since the frequency characteristic of the assist torque is changed, disturbance detection errors other than modeling errors (such as detection errors by sensors) can be made zero, and the disturbance input amount can be calculated accurately.

  In the eighth embodiment, the steering torque when there is no road surface (disturbance) input is estimated from the pinion torque using the steering system model and the vehicle model, and input based on the deviation between the estimated steering wheel torque and the actual steering torque. It is an example which determines the direction of a torque.

Figure 28 is a system block diagram of a controller 12g of the Example 8, in Example 3, enter the pinion torque T _p detected by the pinion torque sensor 17, in the absence of road surface input estimating handle torque (estimated steering wheel and a model (handle-side steering state quantity estimating means) 19 for outputting a side steering state quantity) T _h ^*.

This model 19 includes a steering system model and a vehicle model (such as a motorcycle model or an experimentally determined map or equation), and an estimated handle torque T when there is no road surface (disturbance) input based on the pinion torque T _p. Output _h ^* .

The comparator 13q ″ obtains a deviation T _h ^* −T _h between the estimated handle torque T _h ^* and the detected handle torque T _h and outputs it to the input determination unit 13x ″. The input determination unit 13x ″ determines whether the input is from a human or from the road surface based on T _h ^* −T _h .

The human input correction unit 13y ″ determines the frequency characteristic of the steering angle input filter that corrects human input based on the determination result of the input determination unit 13x ″. The road surface input correction unit 13z "determines the frequency characteristic of the steering angle input filter that corrects the road surface input based on the determination result of the input determination unit 13x".
Other configurations are the same as those in the fifth embodiment, and thus description thereof is omitted.

[Disturbance input estimation by model]
In Example 8, estimates the estimated wheel torque T _h ^* pinion torque T _p using a model 19 to correct the frequency characteristic of the assist torque in accordance with the deviation between the estimated wheel torque T _h ^* and the handle torque T _h Therefore, as compared with the fifth and sixth embodiments, disturbance detection errors other than modeling errors (detection errors by sensors, etc.) can be made zero, and the disturbance input amount can be calculated more accurately.

Next, the effect will be described.
In the electric power steering apparatus according to the eighth embodiment, in addition to the effects (1) to (11) of the first embodiment and the effect (16) of the fifth embodiment, the following effects can be obtained.

(19) as input pinion torque T _h, with an estimated steering wheel torque T _h ^* model 19 to output in the absence of disturbance inputs from the road surface by using a steering system model and the vehicle model, the input determination unit 13x " when a deviation in the steering wheel torque T _h and the estimated wheel torque T _h ^* occurs, it determines the input torque to be input from the road surface, the frequency characteristic correction means, the difference T _h ^* -T _h Accordingly, since the frequency characteristics of the assist torque are changed, disturbance detection errors other than modeling errors (detection errors by sensors, etc.) can be made zero, and the disturbance input amount can be accurately calculated.

  In the ninth embodiment, the yaw rate in the absence of road surface input is estimated from the steering torque using the steering system model and the vehicle model, and the yaw rate in the absence of road surface input is estimated from the pinion torque using the vehicle model. It is an example which determines road surface input based on the deviation of two estimated values.

FIG. 29 is a system block diagram of the controller 12h according to the ninth embodiment.
Model (first vehicle behavior estimation means) 18 'is provided with a steering system model and the vehicle model, first estimated yaw rate (first estimated vehicle behavior) in the case by entering the handle torque T _h no road surface input gamma _p ^* Is output. The model (second vehicle behavior estimating means) 20 includes a vehicle model, and outputs a second estimated yaw rate (second estimated vehicle behavior) γ _h ^* when the pinion torque T _p is input and the driver does not input steering. To do.

The comparator 21 outputs a value obtained by subtracting the first estimated yaw rate γ _p ^* from the second estimated yaw rate γ _h ^* to the input determination unit 22. The input determination unit 22 determines whether the input is from a human or from the road surface based on the deviation γ _h ^* −γ _p ^* .

In the human input correction unit 23, the frequency of the steering angle input filter that corrects the human input based on the determination result (deviation γ _h ^* −γ _p ^* ) of the input determination unit 22 and the yaw rate γ detected by the yaw rate sensor 15. Determine the characteristics. In the road surface input correction unit 24, the frequency of the steering angle input filter that corrects the road surface input based on the determination result (deviation γ _h ^* −γ _p ^* ) of the input determination unit 22 and the yaw rate γ detected by the yaw rate sensor 15. Determine the characteristics.

[Disturbance input estimation by model]
In the ninth embodiment, the first estimated yaw rate γ _p ^* and the second estimated yaw rate γ _h ^* are estimated using the models 18 ′ and 20, and the deviation between the estimated γ _h ^* and γ _p ^* and the actual yaw rate γ Therefore, the disturbance input amount can be accurately estimated and the assist torque for obtaining a desired yaw rate characteristic can be set.

Next, the effect will be described.
In the electric power steering apparatus according to the ninth embodiment, the following effects can be obtained in addition to the effects (1) to (11) of the first embodiment and the effect (16) of the fifth embodiment.

(20) A model 18 ′ that receives the steering torque T _h and outputs the first estimated yaw rate γ _p ^* in the absence of disturbance input from the road surface using the steering system model and the vehicle model, and the pinion torque T _p , And a model 20 that outputs a second estimated yaw rate γ _h ^* when the driver's steering input is not considered using a vehicle model, and the input determination unit 22 has γ _h ^* and γ _p ^*. When there is a deviation, it is determined that the input torque is input from the road surface side, and the frequency characteristic correction means changes the frequency characteristic of the assist torque according to the deviation γ _h ^* −γ _p ^* , so modeling Disturbance detection errors other than errors (detection errors by sensors, etc.) can be reduced to zero, the amount of disturbance input can be accurately calculated, and steering force assist that obtains desired yaw rate characteristics can be realized.

(Other examples)
The best mode for carrying out the present invention has been described based on the first to ninth embodiments. However, the specific configuration of the present invention is not limited to each embodiment, and departs from the gist of the invention. Even if there is a design change within a range not to be included, it is included in the present invention.

  For example, in the ninth embodiment, yaw rate is used as a vehicle behavior parameter, but other parameters such as yaw rate gain, yaw acceleration, lateral velocity, or lateral acceleration may be used.

It is a figure which shows the structure of the electric power steering apparatus of Example 1. FIG. 1 is a system block diagram of a controller 12 according to a first embodiment. 3 is a flowchart illustrating a flow of assist control processing executed by a controller 12 according to the first embodiment. It is a filter characteristic figure at the time of determining with human input. It is a filter characteristic figure at the time of determining with road surface input. It is a filter characteristic figure at the time of determining with human input. It is a filter characteristic figure at the time of determining with road surface input. It is a figure which shows the filter characteristic at the time of low micro road driving | running | working. It is a filter characteristic diagram when the steering wheel angular velocity and the pinion angular velocity are both minimum values and the deviation between the two is slight. It is a filter characteristic figure at the time of low speed driving. It is a filter characteristic figure at the time of high speed driving. It is a filter characteristic figure at the time of medium speed running. FIG. 6 is a filter characteristic diagram when a medium steering angle is maintained for a certain period of time. It is a filter characteristic figure in case it is difficult to determine whether human input is road surface input. It is a figure which shows the response delay of a handle | steering-wheel torque and a pinion torque with respect to the step input from a steering wheel side or a steering wheel side. It is a figure which shows the input direction determination effect | action of Example 1. FIG. It is a system block diagram of the controller 12a of Example 2. It is a flowchart which shows the flow of the assist control process performed with the controller 12a of Example 2. FIG. It is a system block diagram of the controller 12b of Example 3. 10 is a flowchart illustrating a flow of assist control processing executed by a controller 12b according to the third embodiment. FIG. 10 is a system block diagram of a controller 12c according to a fourth embodiment. 14 is a flowchart illustrating a flow of assist control processing executed by a controller 12c according to the fourth embodiment. It is a figure which shows the structure of the electric power steering apparatus of Example 5. FIG. 10 is a system block diagram of a controller 12d according to a fifth embodiment. It is a flowchart which shows the flow of the assist control process performed with the controller 12d of Example 5. FIG. FIG. 10 is a system block diagram of a controller 12e according to a sixth embodiment. FIG. 10 is a system block diagram of a controller 12f according to a seventh embodiment. FIG. 10 is a system block diagram of a controller 12g according to an eighth embodiment. FIG. 10 is a system block diagram of a controller 12h according to a ninth embodiment.

Explanation of symbols

1 Handle 2 Steering shaft 3 Handle angle sensor 4 Pinion angle sensor 5 Pinion 6 Rack shaft 7 Tie rod 8 Front wheel 9 Torque sensor 10 Reducer 11 Motor 12 Controller 14 Battery 15 Yaw rate sensor 16 Vehicle speed sensor

Claims (17)

An input torque detecting means for detecting an input torque to a steering shaft connecting the steering wheel and the steering mechanism;
An assist actuator that outputs an assist torque for assisting the input torque to the steering mechanism;
Assist control means for driving and controlling the assist actuator in accordance with the input torque;
In a power steering apparatus having
A steering-side steering state quantity detecting means for detecting a steering-state quantity on the steering wheel side relative to the assist actuator;
Steering wheel side steering state amount detecting means for detecting a steering state amount on the steered wheel side with respect to the assist actuator;
An input determination means for determining whether the detected input torque is an input from the handle side or an input from the road surface side based on the steering wheel side steering state amount and the steered wheel side steering state amount;
When it is determined that the input torque is input from the steering wheel side, the assist torque gain is increased in a predetermined driver steering frequency region, and the input torque is determined to be input from the road surface side. A frequency characteristic correcting means for correcting the frequency characteristic of the assist torque so as to reduce the gain of the assist torque in a frequency region of disturbance input from a preset road surface when
A power steering apparatus comprising: The power steering apparatus according to claim 1, wherein
When it is determined that the input torque is input from a steering wheel side, the frequency characteristic correcting unit increases a gain of a high frequency component exceeding a predetermined frequency of the assist torque, and the input torque is input from the road surface side. When it is determined that there is a power steering device, the gain of a low frequency component that is equal to or lower than the predetermined frequency of the assist torque is reduced. In the power steering device according to claim 1 or 2,
Vehicle speed detection means for detecting the vehicle speed,
The frequency characteristic correcting unit changes a frequency region for correcting the frequency characteristic of the assist torque according to a change in vehicle speed when it is determined that the input torque is input from a steering wheel side. Power steering device. In the power steering device according to claim 3,
The frequency characteristic correcting means increases a gain of the assist torque in a driver's steering frequency region during low-speed traveling when the vehicle speed is equal to or lower than a predetermined low vehicle speed threshold value. The power steering device according to claim 3, wherein:
The frequency characteristic correcting means increases the gain of the low frequency component of the assist torque below a steering frequency range of the driver when the vehicle speed is higher than a predetermined high vehicle speed threshold. . The power steering apparatus according to any one of claims 3 to 5,
When the vehicle speed is in a vehicle speed region between the low vehicle speed threshold value and the high vehicle speed threshold value, the frequency characteristic correcting unit is configured to reduce the assist torque in the driver's steering frequency region as the vehicle speed increases. A power steering apparatus characterized by lowering the gain of a high frequency component and increasing the gain of a low frequency component. The power steering apparatus according to any one of claims 1 to 6,
A steering holding detection means for detecting a steering holding state in which the steering wheel is held at a predetermined angle for a certain period of time;
The frequency characteristic correcting means increases a gain of an extremely low frequency component of the assist torque when a steering state is detected. The power steering apparatus according to any one of claims 1 to 7,
A road surface friction coefficient detecting means for detecting the road surface friction coefficient of the traveling road is provided,
The frequency characteristic correcting unit increases the gain of the low frequency component of the assist torque and decreases the gain of the high frequency component when the detected road surface friction coefficient is smaller than a predetermined low μ road threshold value. Power steering device. The power steering apparatus according to any one of claims 1 to 8,
A steering state amount change speed for comparing a steering wheel side steering state amount change speed, which is a change speed of the steering wheel side steering amount, and a steering wheel side steering state amount change speed, which is a change speed of the steering wheel side steering state amount. Comparing operation means,
The input determining means determines that the input torque is an input from a steering wheel side when the steering wheel side steering state amount changing speed is larger than the steering wheel side steering state amount changing speed. Steering device. The power steering apparatus according to claim 9, wherein
The input determination means makes the input direction determination impossible when the steering wheel side steering state amount change speed is equal to the steering wheel side steering state amount change speed;
The frequency characteristic correcting means increases the gain of the low frequency component of the assist torque in a region below the steering frequency of the driver when the input direction cannot be determined. In the power steering device according to claim 9 or 10,
The input determining means determines that the steering is corrected when the steering-side steering state amount change speed and the steered-wheel-side steering state amount change speed are both minimum values and the deviation between the two is slight.
The power steering device according to claim 1, wherein the frequency characteristic correcting unit increases a gain of a low frequency component of the assist torque when it is determined that the steering is corrected. The power steering apparatus according to any one of claims 1 to 11,
The power steering device, wherein the input torque detecting means estimates the input torque based on the steering wheel side steering state amount and the steered wheel side steering state amount. The power steering apparatus according to any one of claims 1 to 12,
Steering wheel side steering state quantity estimation means that takes the steering wheel side steering state quantity as an input and outputs an estimated steered wheel side steering state quantity when there is no disturbance input from the road surface using a steering system model and a vehicle model. With
The input determination means determines that the input torque is an input from the road surface side when a deviation occurs between the detected steering wheel side steering state amount and the estimated steering wheel side steering state amount;
The power steering apparatus according to claim 1, wherein the frequency characteristic correcting unit changes a frequency characteristic of the assist torque in accordance with the deviation. The power steering apparatus according to any one of claims 1 to 12,
A steering wheel side steering state quantity estimating means for receiving the steering wheel side steering state quantity as an input, and using the steering system model and the vehicle model as an output, the estimated steering wheel side steering state quantity in a state without disturbance input from the road surface is provided. ,
The input determination means determines that the input torque is an input from the road surface side when a deviation occurs between the detected steering wheel side steering state amount and the estimated steering wheel side steering state amount;
The power steering apparatus according to claim 1, wherein the frequency characteristic correcting unit changes a frequency characteristic of the assist torque in accordance with the deviation. The power steering apparatus according to any one of claims 1 to 14,
The steering-side steering state amount detection means is a steering wheel angle sensor that detects a steering wheel angle that is a rotation angle of a steering shaft closer to the steering wheel than the assist actuator,
The steering wheel side steering state quantity detecting means is a pinion angle sensor that detects a pinion angle that is a rotation angle of a steering shaft on a steering wheel side with respect to the assist actuator. The power steering apparatus according to any one of claims 1 to 14,
The steering wheel side steering state amount detecting means is a steering wheel torque sensor that detects a steering wheel torque that is an input torque to a steering shaft on a steering wheel side relative to the assist actuator,
The steered wheel side steering state amount detecting means is a pinion torque sensor that detects a pinion torque that is an input torque to the steered wheel side steering shaft with respect to the assist actuator. The power steering apparatus according to claim 16, wherein
First vehicle behavior estimation means that takes the steering wheel torque as an input and outputs a first estimated vehicle behavior in the absence of disturbance input from the road surface using a steering system model and a vehicle model;
Second vehicle behavior estimation means for outputting the second estimated vehicle behavior when the pinion torque is input and the driver's steering input is not taken into account using the vehicle model;
With
The input determining means determines that the input torque is an input from the road surface side when a deviation occurs between the first estimated vehicle behavior and the second estimated vehicle behavior;
The power steering apparatus according to claim 1, wherein the frequency characteristic correcting unit changes a frequency characteristic of the assist torque in accordance with the deviation.

Images