Sideslip angle estimation apparatus and method and automotive vehicle incorporating the same

Abstract

In order to enhance the accuracy of estimation of sideslip angle β, a sideslip angle estimation apparatus calculates a first sideslip angle β2 between the direction of centrifugal force acting on the vehicle body during cornering and the lateral direction of the vehicle body based on accelerations exerted on the vehicle body and acting in two different directions. A sideslip angle between the longitudinal direction of the vehicle body and the direction of travel of the vehicle is calculated based on the calculated first sideslip angle β2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:

FIG. 1A is a side view of a vehicle employing a controller capable of executing a sideslip-angle estimation according to embodiments of the invention, and FIG. 1B is a schematic system block diagram of the vehicle;

FIG. 2 is a block diagram showing a sideslip angle estimation apparatus of a first embodiment;

FIG. 3 is an explanatory view showing the principle of action of centrifugal force acting on the vehicle during cornering;

FIG. 4 is an explanatory view showing the principle of action of centrifugal force acting on the vehicle during cornering with a change in vehicle speed;

FIG. 5 is a control map used to calculate a compensation gain;

FIGS. 6A-6D are time charts showing the effects obtained by the apparatus of the first embodiment;

FIG. 7 is a block diagram showing a sideslip angle estimation apparatus of a second embodiment;

FIG. 8 is a control map used to calculate a compensation gain;

FIG. 9 is a diagram explaining an apparatus of a third embodiment;

FIG. 10 is a flow chart showing a gain setting process executed within an apparatus of a fourth embodiment; and

FIGS. 11A-11E are time charts showing the effects obtained by the apparatus of the fourth embodiment.

Claims

1. A sideslip angle estimation apparatus for estimating a sideslip angle of a vehicle, comprising: an acceleration detection section operable to detect acceleration values in two different directions with respect to a vehicle body;a first sideslip angle estimation section operable to estimate a first sideslip angle between a direction of centrifugal force acting on the vehicle body and a lateral direction of the vehicle body based on the acceleration values detected by the acceleration detection section; anda sideslip angle calculation section operable to calculate the sideslip angle of the vehicle based on the first sideslip angle.

2. The sideslip angle estimation apparatus according to claim 1, further comprising: a quantity-of-running-state detection section operable to detect a quantity associated with a running state of the vehicle; anda second sideslip angle estimation section operable to estimate a second sideslip angle between a longitudinal direction of the vehicle body and a direction of travel of the vehicle body via an integral calculus operation that utilizes the quantity associated with the running state,wherein the sideslip angle calculation section is further operable to calculate the sideslip angle of the vehicle based on the first and second sideslip angles.

3. The sideslip angle estimation apparatus according to claim 2 wherein the quantity-of-running-state detection section comprises at least one of a steer angle sensor and a yaw rate sensor.

4. The sideslip angle estimation apparatus according to claim 2, further comprising: a cornering state detection section operable to detect a cornering state of the vehicle,wherein the sideslip angle calculation section is further operable to calculate the sideslip angle of the vehicle using at least one of the first and second sideslip angles depending on the cornering state.

5. The sideslip angle estimation apparatus according to claim 2 wherein the sideslip angle calculation section further comprises a compensation section operable to perform feedback compensation for the integral calculus operation of the second sideslip angle estimation section based on a deviation between the first and second sideslip angles; and wherein the sideslip angle calculation section is further operable to calculate the sideslip angle based on the second sideslip angle compensated by the compensation section.

6. The sideslip angle estimation apparatus according to claim 5, further comprising: a cornering state detection section operable to detect a cornering state of the vehicle; anda compensation gain control section operable to control a weight for the feedback compensation based on the cornering state,wherein the compensation section is further operable to perform the feedback compensation for the integral calculus operation of the second sideslip angle estimation section based on the deviation between the first and second sideslip angles wherein the feedback compensation includes a controlled weight.

7. The sideslip angle estimation apparatus according to claim 6 wherein the compensation gain control section is further operable to increase the weight for the feedback compensation as the cornering state of the vehicle approaches a limit.

8. The sideslip angle estimation apparatus according to claim 6, further comprising: a centrifugal force disappearance decision section operable to determine whether the centrifugal force acting on the vehicle body disappears,wherein the compensation gain control section is further operable to limit the weight for the feedback compensation until the centrifugal force reoccurs after the centrifugal force disappearance decision section determines that the centrifugal force acting on the vehicle body disappears.

9. The sideslip angle estimation apparatus according to claim 8 wherein the compensation gain control section is further operable to limit the weight for the feedback compensation until a predetermined time period has expired from a point of time when the centrifugal force disappearance decision section determines that the centrifugal force acting on the vehicle body disappears.

10. The sideslip angle estimation apparatus according to claim 2, further comprising: a third sideslip angle estimation section operable to estimate a third sideslip angle using direct integration that utilizes the quantity of running state as a parameter;a cornering state detection section that detects a cornering state of the vehicle wherein the sideslip angle calculation section further comprises: a first correction section operable to perform a first feedback correction for the parameter of the third sideslip angle estimation section based on the third sideslip angle and the acceleration values;a second correction section operable to perform a second feedback correction for an integral calculus operation of the third sideslip angle estimation section based on a deviation between the second and third sideslip angles; anda compensation section operable to perform a feedback compensation for the integral calculus operation of the third sideslip angle estimation section based on a deviation between the first and third sideslip angles,wherein the first correction section is further operable to control a weight for the first feedback correction based on the cornering state of the vehicle,wherein the second correction section is further operable to control a weight for the second feedback correction based on the cornering state of the vehicle, andwherein the compensation section is further operable to control a weight for the feedback compensation based on the cornering state of the vehicle; andwherein the sideslip angle calculation section is further operable to calculate the sideslip angle of the vehicle based on the third sideslip angle corrected by the first and second correction sections and by the compensation section.

11. The sideslip angle estimation apparatus according to claim 10 wherein the sideslip angle calculation section is further operable to calculate the sideslip angle of the vehicle based on the third sideslip angle corrected by the first correction section using a controlled weight for the first feedback correction, the second correction section using a controlled weight for the second feedback correction and by the compensation section using a controlled weight for the feedback compensation.

12. The sideslip angle estimation apparatus according to claim 10 wherein the second correction section is further operable to increase the weight for the second feedback correction relative to the weight for the first feedback correct and the weight for the feedback compensation when the cornering state of the vehicle is within a non-cornering region, wherein the first correction section is further operable to increase the weight for the first feedback correction relative to the weight for the second feedback correction and the weight for the feedback compensation when the cornering state of the vehicle is within a moderate cornering region, andwherein the compensation section is further operable to increase the weight for the feedback compensation relative to the weight for the first feedback correction and the weight for the second feedback correction when the cornering state of the vehicle is out of both of the non-cornering region and the moderate cornering region.

13. The sideslip angle estimation apparatus according to claim 1, further comprising: a vehicle-speed variation detection section that detects a variation of vehicle speed,wherein the first sideslip angle estimation section is further operable to estimate the first sideslip angle based on the variation of the vehicle speed and the acceleration values.

14. The sideslip angle estimation apparatus according to claim 1 wherein the acceleration detection section is further operable to detect second acceleration values in two directions, each of the two directions differing from each of longitudinal and lateral directions of the vehicle body.

15. An automotive vehicle comprising the sideslip angle estimation apparatus according to claim 1.

16. A sideslip angle estimation apparatus for estimating a sideslip angle of a vehicle, comprising: first means for detecting a first acceleration in a first direction with respect to a vehicle body;second means for detecting a second acceleration in a second direction with respect to the vehicle body;means for estimating a first sideslip angle between a direction of centrifugal force acting on the vehicle body and a lateral direction of the vehicle body based on the first acceleration and the second acceleration; andmeans for calculating the sideslip angle based on the first sideslip angle.

17. A method of estimating a sideslip angle of a vehicle, comprising: detecting a first acceleration in a first direction with respect to a vehicle body;detecting a second acceleration in a second direction with respect to the vehicle body;estimating a first sideslip angle between a direction of centrifugal force acting on the vehicle body and a lateral direction of the vehicle body based on the first acceleration and the second acceleration; andcalculating the sideslip angle based on the first sideslip angle.

18. The method according to claim 17, further comprising: detecting a vehicle speed;estimating a second sideslip angle between a longitudinal direction of the vehicle body and a direction of travel of the vehicle body via an integral calculus operation using the vehicle speed;detecting a cornering state of the vehicle, and wherein calculating the sideslip angle based on the first sideslip angle further includes calculating the sideslip angle using the first sideslip angle and using the second sideslip angle depending on the cornering state.

19. The method according to claim 17, further comprising: detecting a third acceleration in a third direction with respect to the vehicle body;detecting a fourth acceleration in a fourth direction with respect to the vehicle body;substituting the third acceleration and the fourth acceleration for the first acceleration and the second acceleration when estimating the first sideslip angle between the direction of the centrifugal force acting on the vehicle body and the lateral direction of the vehicle body when at least one of the first acceleration and the second acceleration is less than or equal to a predetermined acceleration value.

20. The method according to claim 19 wherein detecting the first acceleration in the first direction with respect to a vehicle body further comprises detecting a lateral acceleration using a lateral acceleration sensor, wherein detecting the second acceleration in the second direction with respect to the vehicle body further comprises detecting a longitudinal acceleration using a longitudinal acceleration sensor,wherein detecting the third acceleration in the third direction with respect to the vehicle body further comprises detecting an acceleration value of a third acceleration sensor inclined at +45 degrees with respect to the lateral acceleration sensors, andwherein detecting a fourth acceleration in a fourth direction with respect to the vehicle body further comprises detecting an acceleration value of a fourth acceleration sensor inclined at +45 degrees with respect to the longitudinal acceleration sensors.