JP2008049828A - Yaw rate estimating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a yaw rate estimating device capable of estimating the yaw rate with high accuracy even when a vehicle is not in a normal turning state. <P>SOLUTION: The yaw rate estimating device 1 has a control unit which determines a turning state whether or not a vehicle is in a normal turning state and estimates the yaw rate of the vehicle based on the result. The control unit 7 comprises an image processing unit 8 for obtaining the curve radius of a road with its image picked up by a camera 4, and a yaw rate estimation unit 9 for estimating the yaw rate of the vehicle based on the lateral acceleration detected by a lateral acceleration sensor 2, the vehicle speed detected by a vehicle speed sensor 3, the curve radius obtained by the image processing unit 8, the steering speed detected by a steering speed sensor 5, and the longitudinal acceleration detected by a longitudinal acceleration sensor 6. When the vehicle is not in a normal turning state, the yaw rate estimation unit 9 estimates the third yaw rate by taking the weighted mean of the first and second yaw rates, and sets the third yaw rate as a final value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a yaw rate estimation apparatus that estimates a yaw rate of a vehicle.

Conventionally, as a yaw rate estimation apparatus, what was described in the nonpatent literature 1 and the patent document 1, for example is known. The yaw rate estimation device described in Non-Patent Document 1 estimates a yaw rate based on wheel speed and lateral acceleration. When estimating the yaw rate based on the inner / outer wheel speed difference, the yaw rate estimating device described in Patent Document 1 uses the yaw rate estimation parameter based on the inner / outer wheel speed difference based on the estimated yaw rate based on the vehicle speed and lateral acceleration in the steady turning state. Is calculated.
SAE TECHNICAL PAPER SERIES 2000-01-0696, Estimation of Vehicle SideSlip Angle and Yaw Rate, Aleksander Hac and Melinda D. Simpson, Delphi Automotive System Japanese Patent No. 3649036

  However, the yaw rate estimation device using the lateral acceleration as in Non-Patent Document 1 has a problem that the accuracy is deteriorated when it is not in a steady turning state. Further, in Patent Document 1, it is possible to reduce the yaw rate estimation error caused by the difference in the rotational speeds of the inner and outer wheels during turning, but no consideration is given to the estimation of the yaw rate in the unsteady turning state.

  An object of the present invention is to provide a yaw rate estimation device capable of estimating a yaw rate with high accuracy even when the vehicle is not in a steady turning state.

  The yaw rate estimation apparatus according to the present invention includes a vehicle speed detecting means for detecting the vehicle speed of the vehicle, a lateral acceleration detecting means for detecting the lateral acceleration of the vehicle, a vehicle speed detected by the vehicle speed detecting means, and a lateral speed detected by the lateral acceleration detecting means. First yaw rate estimation means for estimating the first yaw rate of the vehicle based on acceleration, second yaw rate estimation means for estimating the second yaw rate of the vehicle by an estimation method different from the estimation method by the first yaw rate estimation means, A third yaw rate estimating means for estimating the third yaw rate of the vehicle based on the yaw rate and the second yaw rate; and a turning state determining means for determining the turning state of the vehicle. When it is determined that the vehicle is not in a steady turning state, the first yaw rate is greater than when the vehicle is determined to be in a steady turning state. It is characterized in estimating a third yaw rate by increasing the weighting of the second yaw rate against.

  Thus, in the present invention, the first yaw rate of the vehicle is estimated using the lateral acceleration of the vehicle, and the second yaw rate of the vehicle is calculated using an estimation method (for example, a curve radius) different from the first yaw rate estimation method. The third yaw rate of the vehicle is estimated based on the first yaw rate and the second yaw rate. Then, the final yaw rate of the vehicle is obtained according to the turning state of the vehicle. For example, when the vehicle is in a steady turning state, the first yaw rate is used as it is as the final yaw rate, and when the vehicle is not in a steady turning state (is in an unsteady turning state), the third yaw rate is used as the final yaw rate. To do. At this time, when the vehicle is not in a steady turning state, a third yaw rate obtained by increasing the weight of the second yaw rate with respect to the first yaw rate is obtained compared to when the vehicle is in a steady turning state. As a result, the yaw rate can be estimated with high accuracy not only when the vehicle is in a steady turning state but also when the vehicle is not in a steady turning state.

  The yaw rate estimation apparatus of the present invention further includes curve radius estimation means for estimating the curve radius of the road on which the vehicle travels, and the third yaw rate estimation means is large when the curve radius estimated by the curve radius estimation means is small. It is preferable that the weighting of the second yaw rate with respect to the first yaw rate is larger than that of the first yaw rate. In general, the smaller the curve radius of the road on which the vehicle travels, the more likely the vehicle will be in an unsteady turning state. Therefore, the curve radius estimating means can estimate the curve radius of the road on which the vehicle actually travels, and the third yaw rate can be estimated based on the estimated curve radius. At this time, when the curve radius is small, the third yaw rate is estimated so that the weight of the second yaw rate is increased with respect to the first yaw rate, compared with the case where the curve radius is large. The error in yaw rate estimation due to the radius can be reliably reduced.

  The yaw rate estimation apparatus of the present invention further includes a steering speed detection means for detecting the steering speed of the vehicle, and the third yaw rate estimation means is higher when the steering speed detected by the steering speed detection means is higher than when the steering speed is lower. The weighting of the second yaw rate with respect to the first yaw rate may be large. In general, the higher the steering speed at which the driver operates the steering, the easier the vehicle is in an unsteady turning state. Accordingly, the steering speed can be detected by the steering speed detecting means, and the third yaw rate can be estimated based on the detected steering speed. At this time, when the steering speed is high, the third yaw rate is estimated so that the weighting of the second yaw rate with respect to the first yaw rate is larger than when the steering speed is low, thereby estimating the yaw rate due to the steering speed. The error can be reduced reliably.

  The yaw rate estimation apparatus of the present invention further includes longitudinal acceleration detection means for detecting longitudinal acceleration of the vehicle, and the third yaw rate estimation means is higher when the longitudinal acceleration detected by the longitudinal acceleration detection means is high than when it is small. The weighting of the second yaw rate with respect to the first yaw rate may be large. In general, the higher the longitudinal acceleration of the vehicle generated by the driver's accelerator operation, the more likely the vehicle will be in an unsteady turning state. Accordingly, the longitudinal acceleration can be detected by the longitudinal acceleration detecting means, and the third yaw rate can be estimated based on the detected longitudinal acceleration. At this time, when the longitudinal acceleration is high, the yaw rate estimation due to the longitudinal acceleration is performed by estimating the third yaw rate so that the weighting of the second yaw rate with respect to the first yaw rate is larger than when the longitudinal acceleration is small. The error can be reduced reliably.

  The yaw rate estimation apparatus of the present invention further comprises curve radius estimation means for estimating the curve radius of the road on which the vehicle travels, and the second yaw rate estimation means is detected by the curve radius and vehicle speed detection means estimated by the curve radius estimation means. The second yaw rate is preferably estimated based on the vehicle speed. Thereby, the second yaw rate can be reliably estimated by an estimation method different from the estimation method of the first yaw rate. In addition, since the second yaw rate is estimated using the curve radius of the road on which the vehicle actually travels, the yaw rate can be estimated not only in the traveling state of the vehicle but also in the road environment. Based on this, it becomes possible to estimate the yaw rate.

  According to the present invention, since the yaw rate can be estimated with high accuracy even when the vehicle is not in a steady turning state, the behavior of the vehicle can be accurately grasped regardless of the turning state of the vehicle.

  Hereinafter, a preferred embodiment of a yaw rate estimation apparatus according to the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  FIG. 1 is a block diagram illustrating a configuration of a yaw rate estimation apparatus according to the present embodiment. The yaw rate estimation apparatus 1 is mounted on a vehicle (not shown), and as shown in FIG. 1, a lateral acceleration sensor 2 that detects the lateral acceleration of the vehicle, a vehicle speed sensor 3 that detects the speed (vehicle speed) of the vehicle, and a vehicle A vehicle 4 that images the road ahead in the traveling direction, a steering speed sensor 5 that detects the steering speed of the vehicle, a longitudinal acceleration sensor 6 that detects the longitudinal acceleration of the vehicle, and a turning state of the vehicle; A control unit 7 for estimating the yaw rate of the vehicle based on the result is provided.

  The control unit 7 performs image processing on a road image ahead of the traveling direction of the vehicle imaged by the camera 4 to obtain a curve radius of the road, the lateral acceleration detected by the lateral acceleration sensor 2, and the vehicle speed sensor 3. A yaw rate estimator 9 for estimating the yaw rate of the vehicle based on the detected vehicle speed, the curve radius determined by the image processor 8, the steering speed detected by the steering speed sensor 5, and the longitudinal acceleration detected by the longitudinal acceleration sensor 6; I have.

によって第１ヨーレートω_ｌａを求めることにより行う。 FIG. 2 is a flowchart showing the yaw rate estimation processing procedure of the yaw rate estimation unit 9. As shown in FIG. 2, when estimation of the yaw rate is started, first, the first yaw rate of the vehicle is estimated based on the lateral acceleration detected by the lateral acceleration sensor 2 and the vehicle speed detected by the vehicle speed sensor 3 (step 1). ). The first yaw rate is estimated when the first yaw rate is ω _la , the lateral acceleration is a _y (m / s ² ), and the vehicle speed is V (m / s).

To obtain the first yaw rate ω _la .

Since in order to estimate the first yaw rate more accurately it is necessary to use a vehicle speed V instead car longitudinal speed V _x, practice the error does not become so large even with a vehicle speed V, the yaw rate estimating apparatus 1 Then, the first yaw rate is estimated using the vehicle speed V.

  Then, it is determined whether or not the vehicle is in a steady turning state (step 2). Specifically, (1) when the displacement amount of the curve radius obtained by the image processing unit 8 is larger than the set value, it is determined that the vehicle enters or exits the curve, and (2) When the steering speed detected by the steering speed sensor 5 is higher than the set value, it is determined that the steering speed is high. (3) When the longitudinal acceleration detected by the longitudinal acceleration sensor 6 is higher than the set value, the longitudinal acceleration is It is determined that the value is high, and it is determined that each is not in a steady turning state (unsteady turning state).

At this time, if it is determined that the vehicle is in a steady turning state, the first yaw rate is set to the final yaw rate ω _est (step 3).

によって第２ヨーレートω_ｃａｍを求めることにより行う。 On the other hand, if it is determined that the vehicle is not in a steady turning state, the second yaw rate is estimated based on the curve radius obtained by the image processing unit 8 and the vehicle speed detected by the vehicle speed sensor 3 (step 4). The second yaw rate is estimated when the second yaw rate is ω _cam , the road curve radius is R (m), and the vehicle speed is V (m / s).

To obtain the second yaw rate ω _cam .

によって第３ヨーレートω_ｅｓｔを求めることにより行う。 When the first yaw rate and the second yaw rate are estimated in this way, the third yaw rate of the vehicle is estimated by taking a weighted average of the first yaw rate and the second yaw rate (step 5). The third yaw rate is estimated when ω _est is the third yaw rate, w ₁ is the design value weight function of the first yaw rate, and w ₂ is the design value weight function of the second yaw rate.

To obtain the third yaw rate ω _est .

となる。なお、第１ヨーレートの適合関数Ｋ_ｌａ及び第２ヨーレートの適合関数Ｋ_ｃａｍは、実験により適切な値が設定される。 In addition, the weighting functions w ₁ and w ₂ in Equation 3 represent the yaw rate using the longitudinal acceleration as a _x (m / s2), the steering speed as γ (rad / s), the steering angular velocity as δ (rad), and the lateral acceleration. When the fitting function of the first yaw rate to be estimated is K _la and the fitting function of the second yaw rate to estimate the yaw rate using the curve radius of the road is K _cam ,

It becomes. Note that the first yaw rate adaptation function _Kla and the second yaw rate adaptation function _Kcam are set to appropriate values through experiments.

  Then, the estimated third yaw rate is set as the final yaw rate (step 6).

As can be seen from Equation 3 and Equation 4 above, when (a) the curve radius of the road is reduced, (b) the steering speed is increased, and (c) the longitudinal acceleration is increased, the weighting of the first yaw rate ω _la is decreased. At the same time, the weighting of the second yaw rate ω _cam is increased. This is because if the road curve radius is small, the driver tends to move suddenly, and if the driver is moving suddenly, the steering speed increases and the longitudinal acceleration increases. It is. For this reason, in the cases (a) to (c), the weighting of the first yaw rate ω _la that decreases the estimation accuracy of the yaw rate is decreased, and the weighting of the second yaw rate ω _cam is increased.

On the other hand, when (A) the curve radius of the road increases, (B) the steering speed decreases, and (C) the longitudinal acceleration decreases, the weighting of the first yaw rate ω _la increases and the weighting of the second yaw rate ω _cam increases. Get smaller. That is, in (A) to (C), since the vehicle approaches a steady turning state, the weight of the first yaw rate ω _la that increases the estimation accuracy of the yaw rate is increased, and the weight of the second yaw rate ω _cam is decreased. .

  In the above, step 1 of the yaw rate estimation unit 9 in the control unit 7 is “the first yaw rate of the vehicle is estimated based on the speed detected by the vehicle speed detection means 3 and the lateral acceleration detected by the lateral acceleration detection means 2. 1 yaw rate estimation means ". Step 4 of the yaw rate estimator 9 constitutes “second yaw rate estimation means for estimating the second yaw rate of the vehicle by an estimation method different from the estimation method by the first yaw rate estimation means”. Step 5 of the yaw rate estimator 9 constitutes “third yaw rate estimating means for estimating the third yaw rate based on the first yaw rate and the second yaw rate”. Step 2 of the camera 4, steering speed sensor 5, longitudinal acceleration sensor 6, image processing unit 8 and yaw rate estimation unit 9 in the control unit 7 constitutes “turning state determination means for determining the turning state of the vehicle”.

  FIG. 3 is a diagram showing an example of the curvature of the curve on the road on which the vehicle travels as a condition for simulating the estimation of the yaw rate. When a simulation was performed using a conventional yaw rate estimation method (corresponding to the first yaw rate) based on the lateral acceleration and the vehicle speed, the results shown in FIG. 4 were obtained. As shown in FIG. 4, it can be seen that the yaw rate estimation error is large when entering the curve (I) and when exiting the curve (III). In other words, when entering the curve (I) and when leaving the curve (III), the steering speed detected by the steering speed sensor 5 is higher than the set value or detected by the longitudinal acceleration sensor 6. When the longitudinal acceleration becomes higher than the set value, the steady turning state is lost, and the estimation error of the yaw rate is increased.

In contrast, in the case of a simulation of the estimated yaw rate by the yaw rate estimating apparatus 1, as shown in FIG. 5, the curve radius (curvature) of the road R, the steering speed gamma, based on the variation of the longitudinal acceleration a _x Thus, by adjusting the weighting w ₁ of the first yaw rate and the weighting w ₂ of the second yaw rate, the result shown in FIG. 6 was obtained.

As shown in FIG. 5, when entering the curve (I), since it is determined that the vehicle is not in a steady turning state, a third yaw rate that takes a weighted average of the first yaw rate and the second yaw rate is estimated, and the curve As the curvature becomes larger (the curve radius becomes smaller), the weight w ₁ of the first yaw rate ω _la becomes smaller and the weight w ₂ of the second yaw rate ω _cam becomes larger. When leaving the curve (III), since it is determined that the vehicle is not in a steady turning state, a third yaw rate that takes a weighted average of the first yaw rate and the second yaw rate is estimated, and the curvature of the curve becomes small (curve As the radius increases, the weight w ₁ of the first yaw rate ω _la increases and the weight w ₂ of the second yaw rate ω _cam decreases. On the other hand, while the vehicle is traveling on a road having a constant curvature (curve radius) (II), the vehicle is determined to be in a steady turning state, so the first yaw rate is the final yaw rate.

  Therefore, as shown in FIG. 6, when the vehicle is in a steady turning state, a result equivalent to the conventional yaw rate estimation method shown in FIG. 4 is obtained. However, when the vehicle is not in a steady turning state, the estimation error of the yaw rate is sufficient. You can see that it has become smaller. Thus, it can be said that the effectiveness of the yaw rate estimation method according to the present embodiment has been clarified.

  According to the yaw rate estimation apparatus 1 as described above, the road radius on which the vehicle actually turns is captured by the camera 4 and image processing is performed to estimate the road curve radius R, and based on the curve radius R and the vehicle speed. A second yaw rate is estimated. When the vehicle is not in a steady turning state, the third yaw rate is obtained by taking a weighted average of the first yaw rate and the second yaw rate by weighting according to the turning state of the vehicle. For this reason, even if the estimation accuracy of the first yaw rate is reduced when the vehicle is not in a steady turning state, the reduction in the accuracy of yaw rate estimation can be suppressed by setting the third yaw rate as the final yaw rate. This makes it possible to estimate the yaw rate with high accuracy even when the vehicle is in a steady turning state or an unsteady turning state.

  In addition, since the second yaw rate is estimated using the curve radius R of the road on which the vehicle actually travels, not only the travel state of the vehicle but also a wide range of conditions including the road environment on which the vehicle actually travels. The yaw rate can be estimated.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the second yaw rate is estimated based on the curve radius and the vehicle speed. However, any estimation method may be used as long as the second yaw rate is estimated by an estimation method different from the first yaw rate, for example, a yaw rate sensor (not shown). The second yaw rate may be estimated on the basis of the yaw rate detected at, the wheel speeds of the inner and outer wheels detected by a wheel speed sensor (not shown), or the like.

  Further, the road image captured by the camera 4 is image-processed by the image processing unit 8 to obtain (estimate) the radius of the road ahead in the vehicle traveling direction. If the curve radius of the road can be estimated, The curve radius may be estimated by any means. For example, the curve radius may be estimated by a navigation system or the like, or the curve radius may be estimated by acquiring curve radius information by road-to-vehicle communication or the like.

  Whether the vehicle is in a steady turning state is determined based on the road curve radius estimated by the image processing unit 8, the steering speed detected by the steering speed sensor 5, and the longitudinal acceleration detected by the longitudinal acceleration sensor 6. However, it may be determined alone or in combination as appropriate. The third yaw rate is estimated based on the first yaw rate and the second yaw rate based on the curve radius of the road obtained by the image processing unit 8, the steering speed detected by the steering speed sensor 5, and the longitudinal acceleration detected by the longitudinal acceleration sensor 6. Although the calculation is performed by the weighting of the yaw rate, it may be calculated alone or may be calculated in combination as appropriate.

  When the vehicle is in a steady turning state, the first yaw rate is the final yaw rate, but the third yaw rate may be the final yaw rate regardless of the turning state of the vehicle. In this case, when the vehicle is not in a steady turning state, the weight of the second yaw rate is increased with respect to the first yaw rate compared to when the vehicle is in a steady turning state. It may be estimated.

It is a block diagram which shows the structure of the yaw rate estimation apparatus which concerns on this embodiment. It is a flowchart which shows the yaw rate estimation process sequence of the yaw rate estimation part in a control unit. It is the figure which showed an example of the curvature of the curve which a vehicle drive | works. It is a figure which shows the yaw rate estimated by the conventional yaw rate estimation method using a lateral acceleration. It is a figure which shows the relationship between the weighting of a 1st yaw rate, and the weighting of a 2nd yaw rate. It is a figure which shows the yaw rate estimated by the yaw rate estimation apparatus which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Yaw rate estimation apparatus, 2 ... Lateral acceleration sensor (lateral acceleration detection means), 3 ... Vehicle speed sensor (vehicle speed detection means), 4 ... Camera (turning state determination means, curve radius estimation means), 5 ... Steering speed sensor (steering) Speed detection means, turning state determination means), 6... Longitudinal acceleration sensor (longitudinal acceleration detection means, turning state determination means), 7... Control unit, 8... Image processing section (turning state determination means, curve radius estimation means), 9 ... Yaw rate estimation unit (first yaw rate estimation means, second yaw rate estimation means, third yaw rate estimation means, turning state determination means).

Claims (5)

Vehicle speed detecting means for detecting the vehicle speed of the vehicle;
Lateral acceleration detecting means for detecting lateral acceleration of the vehicle;
First yaw rate estimation means for estimating a first yaw rate of the vehicle based on a vehicle speed detected by the vehicle speed detection means and a lateral acceleration detected by the lateral acceleration detection means;
Second yaw rate estimation means for estimating the second yaw rate of the vehicle by an estimation method different from the estimation method by the first yaw rate estimation means;
Third yaw rate estimating means for estimating a third yaw rate of the vehicle based on the first yaw rate and the second yaw rate;
Turning state determining means for determining a turning state of the vehicle,
The third yaw rate estimator is configured to detect the first yaw rate when the turning state determining means determines that the vehicle is not in a steady turning state, compared to when the vehicle is determined to be in a steady turning state. A yaw rate estimation apparatus that estimates the third yaw rate by increasing the weight of the second yaw rate. A curve radius estimating means for estimating a curve radius of a road on which the vehicle runs;
2. The third yaw rate estimation means is characterized in that the weight of the second yaw rate with respect to the first yaw rate is larger when the curve radius estimated by the curve radius estimation means is smaller than when the curve radius is large. The yaw rate estimation apparatus described in 1. A steering speed detecting means for detecting a steering speed of the vehicle;
2. The third yaw rate estimation means is characterized in that the weighting of the second yaw rate with respect to the first yaw rate is larger when the steering speed detected by the steering speed detection means is higher than when the steering speed is low. The yaw rate estimation apparatus described in 1. It further comprises longitudinal acceleration detecting means for detecting longitudinal acceleration of the vehicle,
2. The third yaw rate estimation means is characterized in that the weight of the second yaw rate relative to the first yaw rate is larger when the longitudinal acceleration detected by the longitudinal acceleration detection means is high than when the longitudinal acceleration is small. The yaw rate estimation apparatus described in 1. A curve radius estimating means for estimating a curve radius of a road on which the vehicle runs;
5. The second yaw rate estimation unit estimates the second yaw rate based on a curve radius estimated by the curve radius estimation unit and a vehicle speed detected by the vehicle speed detection unit. The yaw rate estimation apparatus according to any one of the above.

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