JP2002104223A - Steering torque presumption device, steering torque presumption method and steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more accurately presume a torque acting on a steering wheel and more appropriately judge a wheel-free state. SOLUTION: A disturbance torque Td as a torque acting on a steering shaft from the outside is presumed based on an inputted steering angle θh and a steering angular velocity ωh by an observer method at a disturbance torque presumption part 64. The presumed disturbance torque Td and a shaft torque Tp acting on the steering shaft are added by an adder 66 to presume a steering torque Th. When an absolute value of this presumed steering torque Th is less than a threshold value and a predetermined time is passed, the wheel-free state is judged by a state judgment part 68. A more precise wheel-free state can be judged by presuming the steering torque Th with a good follow-up property and a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering torque estimating device, a steering torque estimating method, and a steering device, and more particularly, to a steering torque estimating device and a steering torque for estimating a steering torque of a steering wheel in a steering device mounted on a vehicle. The present invention relates to an estimation method and an in-vehicle steering device that outputs a steering reaction force according to operation of a steering wheel.

[0002]

2. Description of the Related Art Conventionally, as this type of steering device, there has been proposed a steering device that determines a steering wheel free state based on a torque acting on a rotation shaft of a steering wheel and a rotation speed of a motor (for example, Japanese Patent Laid-Open No. 2000-2000). -62634). In this device, when the output from the torque sensor attached to the rotation shaft of the handle is 0 and the rotation speed of the motor is detected, it is determined that the handle is released from the hand when the handle is released.

[0003]

However, in such a steering device, there is a case where an appropriate steering-free state cannot be determined. When the steering wheel is suddenly released from the steering wheel holding state, the output from the torque sensor does not become 0 due to the influence of the steering wheel inertia or the like for a certain period of time despite the steering wheel being in the free state. In such a case, in the steering device described above, the determination of the steering wheel free state is performed with a delay. Since the delay in the determination of the steering wheel free state appears as a delay in switching the steering control law, the steering control cannot be properly performed. In addition, when torque is positively applied to the rotating shaft of the steering wheel by steering control or the like, the torque is generated on the rotating shaft of the steering wheel even when the hand is released from the steering wheel. Not done.

Further, when a sufficient self-aligning torque cannot be obtained at a low speed, the steering wheel may stop at a constant steering angle due to the influence of friction of a motor or the like. In this case, it is desired that the steering wheel be returned by positive control. However, in the above-described steering device, even if the torque of the rotating shaft of the steering wheel becomes the value 0, the rotation speed of the motor is not detected. Unable to determine,
The steering wheel stops at a constant steering angle.

[0005] It is an object of the present invention to provide a steering torque estimating apparatus and a steering torque estimating method that more accurately estimate a torque acting on a steering wheel. Another object of the present invention is to determine the steering wheel free state more appropriately.

[0006]

Means for Solving the Problems and Their Functions and Effects The steering torque estimating apparatus, the steering torque estimating method and the steering apparatus according to the present invention employ the following means in order to achieve at least a part of the above object.

A steering torque estimating device according to the present invention is a steering torque estimating device for estimating a steering torque of a steering wheel in a steering device mounted on a vehicle, comprising a steering angle detecting means for detecting a steering angle, and a steering angular speed. Steering angular velocity detecting means, shaft torque detecting means for detecting the axial torque of the rotating shaft of the steering wheel, and the steering torque based on the detected shaft torque, the detected steering angle, and the detected steering angular velocity. And a steering torque estimating means for estimating the steering torque.

In the steering torque estimating apparatus according to the present invention, the shaft torque of the rotating shaft of the steering wheel, the steering angle and the steering angular speed are detected, and the steering torque of the steering wheel is determined based on the detected shaft torque, steering angle and steering angular speed. presume. By performing the estimation of the steering torque based on the shaft torque, the steering angle, and the steering angular velocity, it is possible to more accurately estimate the steering torque.

In the steering torque estimating apparatus according to the present invention, the steering torque estimating means estimates a disturbance torque as a torque input from the outside based on the detected steering angle and the detected steering angular velocity. The apparatus may further include disturbance torque estimating means, and addition estimating means for performing an addition operation on the estimated disturbance torque and the detected shaft torque to estimate the steering torque. This is based on the fact that the steering torque corresponds to the sum of the disturbance torque and the shaft torque. This makes it possible to estimate a more appropriate steering torque even when the torque is being actively applied to the rotating shaft of the steering wheel. In the steering torque estimating device according to the aspect of the present invention, the disturbance torque estimating means includes:
A means for estimating the disturbance torque by an observer technique using the detected steering angle and steering angular velocity using the steering angle, the steering angular velocity, and the disturbance torque as state variables. In this case, the disturbance torque estimating means may be means for calculating the disturbance torque using a state equation represented by the following equation (1). Here, in equation (1), θh is the steering angle, ωh is the steering angular velocity, θh * is the estimated value of the steering angle, ωh * is the estimated value of the steering angular velocity, Td * is the estimated value of the disturbance torque, and Jh is the steering inertia. , Cc is the handle viscosity, and G is the observer gain.

[0010]

(Equation 2)

The steering torque estimating method according to the present invention is a steering torque estimating method for estimating a steering torque of a steering wheel in a steering device mounted on a vehicle, wherein (a) a steering torque is estimated based on an input steering angle and a steering angular velocity. The gist is to estimate a disturbance torque as an externally input torque, and (b) add and calculate the estimated disturbance torque and the input torque of the rotating shaft of the steering wheel to estimate the steering torque. .

According to the steering torque estimating method of the present invention, a more appropriate steering torque can be estimated even in a state in which torque is actively applied to the rotating shaft of the steering wheel.

In the steering torque estimating method according to the present invention, the step (a) is performed by an observer method using the input steering angle and the steering angular velocity using the steering angle, the steering angular velocity and the disturbance torque as state variables. This may be a step of estimating the disturbance torque.
In this case, the above equation (1) can be used as the state equation.

A steering system according to the present invention is a vehicle-mounted steering system that outputs a steering reaction force in accordance with the operation of a steering wheel. The gist of the invention is to provide a steering wheel free state determining means for determining a steering wheel free state based on the steering torque estimated by the torque estimating device.

In the steering device of the present invention, the steering wheel free state is determined based on the more accurate estimation of the steering torque by the steering torque estimating device of the present invention, so that the steering wheel free state can be determined more appropriately.

In the steering apparatus according to the present invention, the steering wheel free state determining means may determine that the absolute value of the estimated steering torque falls from a value larger than the first predetermined value to a value equal to or less than the first predetermined value. It is determined that the steering wheel free state has been reached from the steering wheel non-free state, and the estimated absolute value of the steering torque has increased from a value smaller than a second predetermined value larger than the first predetermined value to a value larger than the second predetermined value. Means for determining that the steering wheel is in the free steering state from the steering wheel free state. This can prevent the determination of the handle free state and the determination of the handle non-free state from being performed frequently. In the steering apparatus according to the aspect of the present invention, the steering wheel free state determination unit may determine that the absolute value of the estimated steering torque is larger than the first predetermined value.
And a means for determining that the steering wheel is in the free steering state from the steering wheel non-free state when a predetermined time has elapsed after the predetermined time has elapsed. In this way, it is possible to prevent an erroneous determination that the instantaneous steering torque value of 0 occurring when the steering wheel is continuously steered from right to left and from left to right is the steering wheel free state.

[0017]

Next, embodiments of the present invention will be described with reference to examples. FIG. 1 is a configuration diagram schematically showing a configuration of a steering device 20 mounted on a vehicle according to one embodiment of the present invention. The steering device 20 of the embodiment, as illustrated,
The steering wheel 30 and the steering torque of the steering wheel 22 are transmitted to the rack 28 via the pinion gear 26 to control the steering wheels 30 and 3.
2 includes a steering shaft 24 for changing the turning angle of 2, a motor 34 for outputting an output torque to the rack 28 via a reduction gear 36 and a pinion gear 38, and an electronic control unit 50 for controlling the entire apparatus.

The electronic control unit 50 is configured as a microprocessor mainly including a CPU 52, and includes a ROM 54 storing a processing program, a RAM 56 temporarily storing data, and an input / output port (not shown). Prepare. The electronic control unit 50 receives a shaft torque Tp from a torque sensor 40 attached to the steering shaft 24, a steering angle θh from a steering angle sensor 42 attached to the steering shaft 24, a vehicle speed V from a vehicle speed sensor 58, and the like. Input via the input port. Also, the electronic control unit 50 outputs the motor 34
A drive signal to the controller is output via an output port.

FIG. 2 illustrates a control block when the electronic control unit 50 of the steering apparatus 20 of the embodiment operates as a handle free state determination block 60 for determining a handle free state in which the handle 22 is released. FIG. The handle free state determination block 60 includes:
As shown, the input steering angle θh and steering angular velocity ω
h and a shaft torque Tp, a steering torque estimating unit 62 for estimating the steering torque Th of the steering wheel 22, and a state determining unit 68 for judging the steering wheel free state based on the steering torque Th estimated by the steering torque estimating unit 62. And The steering torque estimating unit 62 calculates the input steering angle θh.
A disturbance torque estimating unit 64 for externally estimating a disturbance torque Td as a torque acting on the steering shaft 24 from the outside based on the steering angle speed ωh, and a disturbance torque estimating unit 6
And an adder 66 for performing an addition operation on the disturbance torque Td and the shaft torque Tp estimated in Step 4. In the embodiment, the steering angular velocity ωh is obtained by calculation by dividing the difference between the steering angles θh sampled twice (θh−previous θh) by the sampling time.

The disturbance torque estimating section 64 obtains the steering angle θh *, the steering angular velocity ωh *, and the disturbance torque Td * as the estimated values by using the above-described equation (1), and obtains the disturbance torque Td as the estimated value. * Is output as the disturbance torque Td. Here, the observer gain G can be determined by various methods. In the embodiment, the value obtained by the pole arrangement method is used.

Equation (1) can be used as a state equation for the following reason. The dynamic characteristics of the handle 22 can be expressed as a model of the following equation (2). here,
a is a steering angular acceleration.

[0022]

(Equation 3)

Here, a disturbance torque Td as an external input applied to the steering shaft 24 of the handle 22
Is the difference between the steering torque Th and the shaft torque Tp (Td = Td
h-Tp). Then, assuming that the change in the disturbance torque Td is slower than the estimated speed, the disturbance torque Td is assumed.
The above-described equation (1) is derived if an expansion system (the following equations (3) and (4)) is set in which d is regarded as one of the states and the disturbance torque Td as the state quantity is estimated.

[0024]

(Equation 4)

The state determining section 68 includes a steering torque estimating section 62
It is determined that the steering wheel free state has been reached when a predetermined time has elapsed after the absolute value of the steering torque Th estimated from the above becomes smaller than a state larger than the threshold T1, and the absolute value of the estimated steering torque Th is larger than the threshold T1. When the state is changed from a state smaller than T2 to a state larger than T2, it is determined that the steering wheel non-free state is reached. By making the determination of the steering wheel free state and the determination of the steering wheel non-free state have hysteresis using the threshold values T1 and T2, frequent changes in the determination are suppressed. In addition, the steering wheel free state is determined by waiting for a predetermined time to elapse after the estimated absolute value of the steering torque Th is reduced from a state greater than the threshold value T1 and the steering wheel is moved from right to left.
It is possible to prevent an erroneous determination that the state of the instantaneous steering torque Th value 0 generated when steering is performed continuously from left to right as the steering wheel free state.

FIG. 3 is an explanatory view exemplifying a state in which the hand is released from the steering wheel 22 in the steering apparatus 20 of the embodiment. FIG. 3A shows changes in the measured value and the estimated value of the steering angle θh and changes in the measured value and the estimated value of the steering angular velocity ωh.
(B) shows changes in the estimated steering torque Th and the shaft torque Tp. As shown in FIG. 3A, the measured value and the estimated value of the steering angle θh and the measured value and the estimated value of the steering angular velocity ωh are respectively on the same curve, and the estimated value and the measured value match well. Therefore, the disturbance torque T is calculated using the equation (1).
It can be seen that the estimation by the disturbance torque estimation unit 64 for estimating d can sufficiently follow the change of the steering wheel 22. Further, as shown in FIG. 3B, after the hand is released from the steering wheel 22, a sinusoidal torque acts on the steering shaft 24 by the active control, but the steering torque Th is close to 0. You can see it calm down. That is, in the steering device 20 of the embodiment, even if the torque is acting on the steering shaft 24 by the active control,
Since the steering torque Th can be more accurately estimated, the steering wheel free state can be determined based on the steering torque Th.

FIG. 4 is an explanatory view exemplifying a state in which the driver returns the handle 22 while holding the handle 22 in the steering device 20 of the embodiment. FIG. 4A shows changes in the measured and estimated values of the steering angle θh and changes in the measured and estimated values of the steering angular velocity ωh, and FIG. 4B shows changes in the estimated steering torque Th and the shaft torque Tp. . FIG. 4 (b)
As shown in (2), since the estimated steering torque Th gradually decreases, it is understood that the situation in which the driver grips the steering wheel 22 and slowly returns the steering wheel 22 can be estimated. The steering wheel free state is not determined until the driver finishes returning the steering wheel 22.

According to the steering apparatus 20 of the embodiment described above, the disturbance torque Td acting as an externally applied torque on the steering shaft 24 is estimated based on the steering angle θh and the steering angular velocity ωh.
The steering torque Th can be estimated by adding the shaft torque Tp acting on the steering torque Th. Moreover, since the disturbance torque Td is estimated using the observer method, the disturbance torque Td can be estimated with high accuracy and with good tracking.
As a result, the steering torque Th can be estimated with high accuracy and good tracking.

Further, according to the steering apparatus 20 of the embodiment, since the steering wheel free state is determined based on the steering torque Th estimated with high accuracy and high accuracy, the steering wheel free state can be determined more accurately. Moreover, the threshold value T1
Since the determination of the steering wheel free state and the determination of the steering wheel non-free state are provided with hysteresis using the threshold value and the threshold value T2, it is possible to prevent the determination from frequently changing.
Further, even if the estimated absolute value of the steering torque Th is reduced from a state larger than the threshold value T1, the steering wheel is not determined to be in the steering wheel free state until a predetermined time has elapsed, so that the steering wheel is continuously moved from right to left and left to right. It is possible to prevent an erroneous determination that the instantaneous steering torque Th having a value of 0 generated during steering is the steering wheel free state.

In the steering apparatus 20 of the embodiment, the difference between the steering angles θh sampled twice (θh−previous θ
h) is divided by the sampling time to calculate the steering angular velocity ωh, but the steering angular velocity ωh may be directly sensed.

In the steering apparatus 20 according to the embodiment, the estimated steering torque Th is used for determining whether the steering wheel is free.
The estimated steering torque Th may be used for various controls other than the determination of the steering wheel free state.

In the steering apparatus 20 according to the embodiment, the determination of the steering wheel free state and the determination of the steering wheel non-free state are provided with hysteresis using the threshold value T1 and the threshold value T2. Absent. In addition, even if the estimated absolute value of the steering torque Th is reduced from a state larger than the threshold value T1, the state is not determined to be the steering wheel free state until a predetermined time has elapsed, but the steering free state is not waited for the predetermined time to elapse. The judgment may be made.

In the steering device 20 of the embodiment, when a sufficient self-aligning torque cannot be obtained at a low speed and the steering wheel stops at a constant angle due to the influence of the friction of the motor or the like, From the equation (2), the steering torque Th becomes zero and the steering wheel free state can be determined.

The embodiments of the present invention have been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various embodiments may be made without departing from the scope of the present invention. Of course, it can be carried out.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a configuration of a steering device 20 mounted on a vehicle according to an embodiment of the present invention.

FIG. 2 is an electronic control unit 5 of the steering device 20 according to the embodiment;
FIG. 10 is an explanatory diagram illustrating a control block when operating as a handle free state determination block 60 for determining a handle free state in which 0 is a state in which the handle 22 is released.

FIG. 3 shows a steering wheel 22 in the steering device 20 according to the embodiment.
It is explanatory drawing which illustrates the state at the time of releasing a hand from.

FIG. 4 is an explanatory diagram illustrating a state in which the driver returns the steering wheel 22 while holding the steering wheel 22 in the steering device 20 of the embodiment.

[Explanation of symbols]

20 steering device, 22 steering wheel, 24 steering shaft, 26 pinion gear, 28 rack, 30,
32 steering wheel, 34 motor, 36 reduction gear, 38 pinion gear, 40 torque sensor, 42 steering angle sensor, 50 electronic control unit, 52 CPU, 54 R
OM, 56 RAM, 58 vehicle speed sensor, 60 steering wheel free state determination block, 62 steering torque estimator,
64 disturbance torque estimator, 66 adder, 68 state determiner.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) B62D 119: 00 B62D 119: 00 (72) Inventor Shoji Asai 41st Nagatute-cho, Yakumichi, Nagakute-cho, Aichi-gun, Aichi, Japan (1) Toyota Central Research Laboratory Co., Ltd. (72) Inventor Toshihiro Takahashi 1-1-1, Asahi-cho, Kariya-shi, Aichi Prefecture Toyota Koki Co., Ltd. (72) Inventor Mineichi 1-1, Asahi-cho, Kariya-shi, Aichi Prefecture F term in Toyota Koki Co., Ltd. (reference) 3D032 CC50 DA03 DA09 DA15 DA23 EB11 EC21 3D033 CA02 CA13 CA16 CA17 CA19 CA28 CA29

Claims (9)

[Claims] 1. A steering torque estimating device for estimating a steering torque of a steering wheel in a steering device mounted on a vehicle, comprising: a steering angle detecting device for detecting a steering angle; a steering angular speed detecting device for detecting a steering angular speed; Shaft torque detecting means for detecting a shaft torque of a rotating shaft of a steering wheel; steering torque estimating means for estimating the steering torque based on the detected shaft torque, the detected steering angle, and the detected steering angular velocity A steering torque estimating device comprising: 2. The steering torque estimating means includes: a disturbance torque estimating means for estimating a disturbance torque as a torque input from the outside based on the detected steering angle and the detected steering angular velocity; The steering torque estimating device according to claim 1, further comprising: an addition estimating unit that performs an addition operation on the detected disturbance torque and the detected shaft torque to estimate the steering torque. 3. The disturbance torque estimating means is a means for estimating the disturbance torque by an observer technique using the detected steering angle and steering angular velocity using the steering angle, the steering angular velocity, and the disturbance torque as state variables. The steering torque estimating device according to claim 2. 4. The steering torque estimating apparatus according to claim 3, wherein said disturbance torque estimating means is means for calculating said disturbance torque using a state equation represented by the following equation. (Equation 1) 5. A steering torque estimating method for estimating a steering torque of a steering wheel in a steering device mounted on a vehicle, the method comprising: (a) determining a torque input from outside based on an input steering angle and a steering angular velocity; (B) a steering torque estimating method of estimating the steering torque by adding and calculating the estimated disturbance torque and the input torque of the rotating shaft of the steering wheel. 6. The step (a) is a step of estimating the disturbance torque by an observer technique using the input steering angle and steering angular velocity with the steering angle, the steering angular velocity and the disturbance torque as state variables. The steering torque estimating method according to claim 5. 7. An in-vehicle steering device that outputs a steering reaction force according to operation of a steering wheel, wherein the steering torque estimating device according to any one of claims 1 to 4, and the steering torque estimating device estimates the steering torque. A steering wheel free state determining means for determining a steering wheel free state based on a steering torque. 8. The steering wheel free state judging means changes the steering wheel non-free state to a steering wheel when the estimated absolute value of the steering torque falls from a value greater than a first predetermined value to a value equal to or less than the first predetermined value. It is determined that the steering wheel is in the free state, and when the absolute value of the estimated steering torque is changed from a value smaller than a second predetermined value larger than the first predetermined value to a value larger than the second predetermined value, the steering wheel free state is set. 8. The steering apparatus according to claim 7, wherein the steering device is configured to determine that the steering wheel non-free state has been reached. 9. The steering wheel free state determination means, when the absolute value of the estimated steering torque has decreased from a value greater than the first predetermined value to a value equal to or less than the first predetermined value, and a predetermined time has elapsed. The steering device according to claim 8, wherein the steering device is means for determining that a steering free state has been reached from a non-free state.