JP5402244B2 - Vehicle physical quantity estimation device - Google Patents

Description

  The present invention relates to a vehicle physical quantity estimation device for estimating a vehicle physical quantity.

  As a conventional vehicle physical quantity estimation device, for example, as described in Patent Document 1, a device that detects and estimates a vehicle offset or yaw angle based on an image of a front road acquired by a CCD camera is known. Yes.

JP 2005-343260 A

  By the way, in the said vehicle physical quantity estimation apparatus, what was provided with the vehicle physical quantity estimation means (what is called a vehicle physical quantity observer) which estimates the vehicle physical quantity which is a physical quantity regarding a vehicle is known. In such a vehicle physical quantity estimation device, when the slip angle is estimated, an error due to the physical relationship between the yaw angle and the slip angle may occur in the estimation.

That is, for example, with respect to the offset D of the vehicle X, there is a physical relationship shown in the following equation (a) between the yaw angle θ and the slip angle β. Even if an error α (hereinafter referred to as “offset error α”) occurs in each of the yaw angle estimated value θ ^ and slip angle estimated value β ^ as vehicle physical quantities, the offset errors α cancel each other out in the whole equation. The physical relationship between the estimated yaw angle value θ ^ and the estimated slip angle value β ^ may be satisfied.
dD / dt = V [θ + β] (a)
dD / dt = V [θ ^ + β ^] = V [(θ−α) + (β + α)] (b)
However, dD / dt: time differential value of offset, V: vehicle speed.

  Therefore, in recent vehicle physical quantity estimation devices, it is strongly desired to accurately estimate the slip angle.

  Then, this invention makes it a subject to provide the vehicle physical-quantity estimation apparatus which can estimate a slip angle accurately.

  In order to solve the above-described problem, a vehicle physical quantity estimation device according to the present invention includes vehicle physical quantity estimation means for estimating a vehicle physical quantity that is a physical quantity related to a vehicle, and yaw angle detection means for detecting a yaw angle of the vehicle. The physical quantity estimation means corrects the slip angle as the estimated vehicle physical quantity based on the yaw angle as the estimated vehicle physical quantity and the yaw angle detected by the yaw angle detection means.

  In this vehicle physical quantity estimation device, the slip angle estimated by the vehicle physical quantity estimation means is corrected based on the yaw angle estimated by the vehicle physical quantity estimation means and the yaw angle detected by the yaw angle detection means. Therefore, even if an offset error occurs in the estimated slip angle, the offset error can be suppressed from the physical relationship between the yaw angle and the slip angle. Therefore, it is possible to accurately estimate the slip angle.

  Here, as a configuration that favorably achieves the above-described effects, specifically, the vehicle physical quantity estimation means calculates the difference between the yaw angle as the estimated vehicle physical quantity and the yaw angle detected by the yaw angle detection means as an offset error. And the structure which correct | amends the slip angle as an estimated vehicle physical quantity with an offset error is mentioned.

  Further, the yaw angle detection means may detect the yaw angle using an in-vehicle camera or GPS.

  Further, the vehicle physical quantity estimation means estimates the vehicle physical quantity in consideration of the road surface inclination of the road on which the vehicle travels. Based on this, it is preferable to estimate the offset, yaw angle, slip angle, and yaw rate as vehicle physical quantities. In this case, the vehicle physical quantity can be estimated in consideration of the road surface inclination.

  According to the present invention, it is possible to accurately estimate the slip angle.

It is a block diagram which shows the vehicle physical quantity estimation apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the road information which a vehicle-mounted camera detects.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted. Further, “^” added on the symbol means an estimated value, and “˜” added on the symbol means a corrected value. For the convenience of description, these “^” and “˜” may be added to the upper right of the symbol.

  FIG. 1 is a block diagram showing a vehicle physical quantity estimation device 1 according to an embodiment of the present embodiment. As shown in FIG. 1, a vehicle physical quantity estimation device 1 according to the present embodiment is mounted on a vehicle X such as an automobile, and estimates a vehicle physical quantity that is a physical quantity related to the vehicle X (hereinafter simply referred to as “vehicle physical quantity”). is there. The vehicle physical quantity estimation device 1 includes a steering angle sensor 2, a yaw rate sensor 3, and an in-vehicle camera (yaw angle detection means) 4.

  The steering angle sensor 2 detects and acquires the steering angle δ of the vehicle X. The yaw rate sensor 3 detects and acquires the yaw rate γ of the vehicle X. The in-vehicle camera 4 functions as a road shape estimation unit, and detects and acquires road information (also referred to as vehicle trajectory information) that is a parameter related to a road on which the vehicle X travels. As shown in FIG. 2, the in-vehicle camera 4 here is based on a road image around the vehicle X, and an offset D that is a relative distance between the road center 11 and the vehicle X and a yaw that is an angle of the vehicle X with respect to the road 10. The angle θ and the curvature (that is, 1 / curve R) C of the road 10 are estimated.

  Returning to FIG. 1, the vehicle physical quantity estimation device 1 includes an ECU (Electronic Control Unit: vehicle physical quantity estimation means) 5 constituted by, for example, a CPU, a ROM, a RAM, and the like. The ECU 5 includes a vehicle physical quantity observer 5a that estimates a vehicle physical quantity based on output values from the sensors 2 to 4, an offset error estimation unit 5b that estimates an offset error α described later, and a yaw angle estimated by the vehicle physical quantity observer 5a. The yaw angle correction unit 5c for correcting the estimated value θ ^ and the slip angle correction unit 5d for correcting the slip angle estimated value β ^ estimated by the vehicle physical quantity observer 5a are configured.

  In the vehicle physical quantity estimation device 1 configured as described above, when the vehicle X travels on the road 10, the following processing is sequentially performed. That is, first, the steering angle δ, the yaw rate γ, the offset D, the yaw angle θ, and the curvature C are output as output values from the sensors 2 to 4 to the vehicle physical quantity observer 5a.

但し、Ｋ：オブザーバゲイン、Ｃ_ｆ：前輪コーナリングフォース、Ｃ_ｒ：後輪コーナリングフォース、ｍ：車両Ｘの質量、Ｖ：車速、ｌ_ｆ：重心から前輪軸中心までの距離、ｌ_ｒ：重心から後輪軸中心までの距離、Ｉ_ｚ：車両Ｘの断面２次モーメント。 Subsequently, a calculation based on the output value is executed by the vehicle physical quantity observer 5a, and an offset estimated value D ^, a yaw angle estimated value θ ^, a slip angle estimated value β ^, and a yaw rate estimated value γ ^ are estimated. Specifically, in the vehicle physical quantity observer 5a, a model in which the curvature C and the road camber (road slope, cant) are expanded is incorporated, and the calculation according to the following expression (1) is executed based on the output value.

Where K: observer gain, C _f : front wheel cornering force, C _r : rear wheel cornering force, m: mass of vehicle X, V: vehicle speed, l _f : distance from the center of gravity to center of front wheel axis, l _r : from center of gravity Distance to the center of the rear wheel axis, I _z : secondary moment of inertia of the vehicle X

但し、ｌ：ｌ_ｆ+ｌ_ｒ、Ａ：スタビリティファクタ。 Here, the load camber amount Y is calculated by an equation of motion (see the following equation (2)) in consideration of the road camber of the road 10 when the vehicle X turns, and an acceleration sensor (G sensor) or the like is used. It is unnecessary. Therefore, an error caused by an acceleration sensor or the like can be removed.

Here, l: l _f + l _r , A: stability factor.

Here, the physical relationship between the time differential value dD / dt of the offset D, the yaw angle θ, and the slip angle β is expressed by the following equation (3). Therefore, for example, as shown in the following equation (4), even if the offset error α actually occurs in each of the yaw angle estimated value θ ^ and the slip angle estimated value β ^, It is found that such physical relationships are satisfied because they cancel each other.
dD / dt = V [θ + β] (3)
dD / dt = V [θ ^ + β ^] = V [(θ−α) + (β + α)] (4)

Therefore, in this embodiment, the offset error estimation unit 5b estimates the offset error α based on the yaw angle estimated value θ ^ estimated by the vehicle physical quantity observer 5a and the yaw angle θ output by the in-vehicle camera 4. Specifically, the offset error α is estimated according to the following equation (5).
α = θ−θ ^ (5)

Subsequently, the slip angle correction unit 5d corrects the slip angle estimated value β ^ based on the offset error α, and calculates a slip angle correction candidate value β _t ^˜ . Specifically, the slip angle correction candidate value β _t ^˜ is derived from the slip angle estimated value β ^ according to the following equation (6).
β _t ^〜 = β ^ −α (6)

When the slip angle correction candidate value β _t ^˜ is averaged during a predetermined time, and the average value β _ave ^˜ and the slip angle correction candidate value β _t ^˜ deviate by more than a threshold value, the rate of change according to the divergence The slip angle estimated value β ^ is corrected so as to change, and the slip angle corrected estimated value β ^~ is calculated.

Further, when the yaw angle correction unit 5e averages the estimated yaw angle θ ^ during a predetermined time and the average value θ _ave ^ deviates from the yaw angle θ output from the in-vehicle camera 4 by a threshold value or more, such deviation The yaw angle estimated value θ ^ is corrected so as to change at a rate of change according to, and the yaw angle corrected estimated value θ ^~ is calculated.

As described above, in this embodiment, the vehicle physical quantity observer 5a considering the road camber is constructed using the vehicle motion information (steering angle δ and yaw rate γ) and the vehicle trajectory information (offset D, yaw angle θ, and curvature C). ing. Then, an offset error α is calculated from the yaw angle estimated value θ ^ estimated by the vehicle physical quantity observer 5a and the yaw angle θ detected by the in-vehicle camera 4, and the slip angle estimated value β ^ is corrected by the offset error α. Yes. That is, the slip angle estimated value β ^ is corrected based on the yaw angle θ and the yaw angle estimated value θ ^ so that the offset error α is suppressed, and the slip angle corrected estimated value β ¹ is obtained.

Thus, for example, even if an offset error occurs in the slip angle estimated value beta ^, ^in-slip angle corrected estimate beta can suppress the offset error alpha. That is, according to the present embodiment, it is possible to accurately estimate the slip angle β.

  Note that if the load camber amount and the slip angle β are estimated from the acceleration sensor, they are easily affected by noise. Further, it is theoretically particularly difficult to remove the offset error α in the acceleration sensor. In this respect, the present embodiment is useful because the acceleration sensor is unnecessary as described above.

  In addition, since a completely flat place is limited to, for example, a factory at the time of shipment of the vehicle X, if the vehicle physical quantity estimation device 1 does not consider the load camber, the estimation accuracy of the slip angle β is substantially increased. May be reduced. On the other hand, in the present embodiment, as described above, since the extended model considering the road camber is incorporated in the vehicle physical quantity observer 5a, the slip angle β is accurately estimated even when traveling on any road or place. It becomes possible.

  Incidentally, it is usually difficult to determine the authenticity of these values only from the relationship between the offset D, the yaw angle θ, and the slip angle β detected by the in-vehicle camera 4.

  As mentioned above, although preferred embodiment of this invention was described, the vehicle physical-quantity estimation apparatus which concerns on this invention is not restricted to the said vehicle physical-quantity estimation apparatus 1 which concerns on embodiment, The summary described in each claim was changed. It may be modified within the range not applied, or applied to other things.

  For example, in the above embodiment, the in-vehicle camera 4 is used as the yaw angle detection means for detecting the yaw angle θ of the vehicle X, but a GPS (Global Positioning System) or the like may be used.

  Since the offset error α is stationary, noise removal may be performed by filtering the offset error α with a low-pass filter. In this case, the estimation accuracy of the slip angle β can be further improved.

  Incidentally, the estimation accuracy of the vehicle physical quantity observer 5a is usually higher when the road shape is closer to a straight line. Therefore, for example, when it is determined that the road shape is close to a straight line from the detected curve R (curvature C), steering angle δ or yaw rate γ, the yaw angle θ can be corrected, while the road shape is other than a straight line (for example, A curve or the like), correction may be prohibited, the rate of change in correction may be reduced (correction speed may be reduced), or the cutoff frequency of the low-pass filter may be varied. .

  In the above-described embodiment, the slip angle correction unit 5d and the yaw angle correction unit 5c each perform the correction to change the slip angle estimated value β ^ and the yaw angle estimated value θ ^ with the change rate. The method is not limited to this, and various methods such as weight correction may be used.

DESCRIPTION OF SYMBOLS 1 ... Vehicle physical quantity estimation apparatus, 4 ... In-vehicle camera (yaw angle detection means), 5 ... ECU (vehicle physical quantity estimation means), 10 ... Road, X ... Vehicle.

Claims (3)

Vehicle physical quantity estimating means for estimating a vehicle physical quantity that is a physical quantity related to the vehicle;
Yaw angle detection means for detecting the yaw angle of the vehicle;
Means for detecting a steering angle of the vehicle;
Means for detecting the yaw rate of the vehicle;
Means for detecting an offset that is a relative distance between a road center and the vehicle;
Means for detecting the curvature of the road on which the vehicle travels ,
The vehicle physical quantity estimating means includes
The vehicle physical quantity is estimated in consideration of the road surface inclination of the road on which the vehicle travels,
Based on the detected steering angle, yaw rate, offset of the road center and the relative distance of the vehicle, yaw angle and the curvature of the road on which the vehicle travels, the offset, yaw of the road center and the relative distance of the vehicle. Estimating the angle, slip angle and yaw rate as the vehicle physical quantity,
A vehicle physical quantity estimation device that corrects the estimated slip angle as the vehicle physical quantity based on the estimated yaw angle as the vehicle physical quantity and the yaw angle detected by the yaw angle detection means.   The vehicle physical quantity estimation means calculates an offset error from the difference between the estimated yaw angle as the vehicle physical quantity and the yaw angle detected by the yaw angle detection means, and uses the estimated slip angle as the vehicle physical quantity as the offset error. The vehicle physical quantity estimation apparatus according to claim 1, wherein the correction is performed by   The vehicle physical quantity estimation device according to claim 1 or 2, wherein the yaw angle detection means detects a yaw angle using an in-vehicle camera or GPS.

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