Source: http://www.google.fr/patents/US8024099
Timestamp: 2013-12-12 23:17:51
Document Index: 125859767

Matched Legal Cases: ['art 21', 'art 26', 'art 25', 'art 26', 'art 22', 'art 21', 'art 26', 'art 23', 'art 22', 'art 24', 'art 23', 'art 21', 'art 21', 'art 31', 'art 32', 'art 31', 'art 31', 'art 32', 'art 32', 'art 31', 'ART=0', 'ART=0', 'art 23']

Brevet US8024099 - Deceleration controller for vehicle - Google�BrevetsRecherche Images Maps Play YouTube Actualit�s Gmail Drive Plus » Recherche avanc�e dans les brevets | Connexion Recherche avanc�e dans les brevets BrevetsA deceleration control apparatus and method for controlling deceleration of a vehicle where a controller is operable to set a target vehicular speed calculated based on a turning condition of the vehicle and a lateral acceleration limitation value. The controller is also operable to apply deceleration...http://www.google.fr/patents/US8024099?utm_source=gb-gplus-shareBrevet US8024099 - Deceleration controller for vehicle Num�ro de publicationUS8024099 B2Type de publicationOctroi Num�ro de demandeUS 11/591,348 Date de publication20 sept. 2011 Date de d�p�t1 nov. 2006 Date de priorit�7 nov. 2005Autre r�f�rence de publicationCN1962326A, CN1962326B, US20070106445 Num�ro de publication11591348, 591348, US 8024099 B2, US 8024099B2, US-B2-8024099, US8024099 B2, US8024099B2 InventeursTatsuya Suzuki, Shinji Matsumoto, Masahide Nakamura, Tomohiro Jimbo Cessionnaire d'origineNissan Motor Co., Ltd.Exporter la citationBiBTeX, EndNote, RefManCitations de brevets (37), R�f�renc� par (3), Classifications (27), �v�nements juridiques (1) Liens externes: USPTO, Cession USPTO, EspacenetDeceleration controller for vehicleUS 8024099 B2 R�sum� A deceleration control apparatus and method for controlling deceleration of a vehicle where a controller is operable to set a target vehicular speed calculated based on a turning condition of the vehicle and a lateral acceleration limitation value. The controller is also operable to apply deceleration to the vehicle based on the actual vehicular speed and the target vehicular speed and to correct the deceleration used when the vehicle is traveling along a detected curve. Correcting the deceleration can be done by, for example, correcting the lateral acceleration limitation value.
a speed sensor for detecting an actual vehicular speed;
a detection device operable to detect a start of a curve in a path of the vehicle; and
compute a lateral acceleration limitation value as the vehicle enters the curve based on the distance of the vehicle from the start of the curve, wherein the lateral acceleration limitation value decreases from a maximum prescribed lateral acceleration value in advance of the curve to a reference lateral acceleration value at the start of the curve, wherein the reference lateral acceleration is based on the radius of the curve and is smaller than the prescribed lateral acceleration value;
set a target vehicular speed calculated based on the lateral acceleration limitation value and a yaw rate of the vehicle, wherein the target vehicular speed decreases as the lateral acceleration limitation value decreases, and the target vehicular speed decreases as the yaw rate of the vehicle increases; and
apply deceleration to the vehicle if the actual vehicular speed exceeds the target vehicular speed.
2. The deceleration control apparatus according to claim 1 wherein the controller is further operable to:
reduce the reference lateral acceleration value as the radius of the curve decreases; and
increase the reference lateral acceleration value as the radius of the curve increases.
3. The deceleration control apparatus according to claim 1 wherein the controller is further operable to:
reduce the reference lateral acceleration value as a difference between a preset vehicle speed and the actual vehicular speed prior to entry of the vehicle into the curve, the preset vehicle speed based on the radius of the curve.
4. The deceleration control apparatus according to claim 1 wherein the controller is further operable to:
compute the lateral acceleration limitation value as the vehicle exits the curve based on the distance of the vehicle from the end of the curve, wherein the lateral acceleration limitation value increases from the reference lateral acceleration value in advance of the end of the curve to the prescribed lateral acceleration value at the end of the curve.
compute the lateral acceleration limitation value by increasing the lateral acceleration limitation value from the reference lateral acceleration value to the prescribed lateral acceleration value as the vehicle approaches an exit of the curve, after the vehicle has passed a point where the radius of the curve is at a minimum value.
override the computation of the lateral acceleration limitation value by setting the lateral acceleration limitation value equal to the prescribed lateral acceleration value when the accelerator operation is detected.
override the computation of the lateral acceleration limitation value by setting the lateral acceleration limitation value equal to the prescribed lateral acceleration value when a turning direction of the curve is opposite a steering direction.
override the computation of the lateral acceleration limitation value by setting the lateral acceleration limitation value equal to the prescribed lateral acceleration value when the radius of the curve is greater than a prescribed upper limit value.
9. A deceleration control apparatus for a vehicle, the apparatus comprising:
means for detecting a start of a curve in a path of the vehicle;
means for computing a lateral acceleration limitation value that decreases from a maximum prescribed lateral acceleration value to a reference lateral acceleration value based on a distance of the vehicle from the start of the curve, wherein the reference lateral acceleration value is based upon the radius of the curve;
means for setting a target vehicular speed calculated based on a yaw rate of the vehicle and the lateral acceleration limitation value, wherein the target vehicular speed decreases as the lateral acceleration limitation value decreases, and the target vehicular speed decreases as the yaw rate of the vehicle increases; and
means for applying deceleration to the vehicle based on the actual vehicular speed and the target vehicular speed.
10. A method for controlling deceleration of a vehicle, comprising:
detecting a start of a curve in a path of the vehicle;
computing a lateral acceleration limitation value as the vehicle enters the curve based on the distance of the vehicle from the start of the curve, wherein the lateral acceleration limitation value decreases from a maximum prescribed lateral acceleration value in advance of the curve to a reference lateral acceleration value at the start of the curve, and the reference lateral acceleration value is based upon the radius of the curve;
setting a target vehicular speed based on a yaw rate of the vehicle and the lateral acceleration limitation value; and
applying deceleration control to the vehicle if an actual speed of the vehicle is greater than the target vehicular speed.
11. The method for controlling deceleration according to claim 10, further comprising:
overriding the computation of the lateral acceleration limitation value by setting the lateral acceleration limitation value equal to the prescribed lateral acceleration value when the accelerator operation is detected.
12. The method for controlling deceleration according to claim 10, further comprising:
correcting the deceleration control by reducing the reference lateral acceleration value as the radius of the curve decreases.
13. The method for controlling deceleration according to claim 10, further comprising:
computing the reference lateral acceleration value based additionally on a difference between the preset vehicle speed and an actual speed of the vehicle prior to entry of the vehicle into the curve.
14. The deceleration control apparatus according to claim 1 wherein the controller is further operable to set the target vehicle speed at prescribed intervals.
15. The deceleration control apparatus according to claim 1 wherein the controller is further operable to set the target vehicular speed to reflect changes in the yaw rate as the vehicle travels along the curve. Description
CROSS-REFERENCES TO RELATED APPLICATIONS This application claims priority from Japanese Patent Application Serial No. 2005-322307, filed Nov. 7, 2005, which is incorporated herein in its entirety by reference.
TECHNICAL FIELD The present invention pertains to a deceleration controller for a vehicle, which controller is used for deceleration control of a vehicle when making a curve, for example.
BACKGROUND There are known deceleration controllers for vehicles. For example, in Japanese Kokai Patent Application No. Hei 10[1998]-278762, a safe vehicular speed for making a curve is computed based on a given turning condition of the vehicle and an allowable level of lateral acceleration preset according to a road-surface friction coefficient. The speed is automatically reduced to a safe vehicular speed, or lower, by an automatic braking system if the vehicle is about to exceed the safe vehicular speed in order to prevent spinning, drifting and overturning.
SUMMARY In one vehicle deceleration control apparatus taught herein, the apparatus comprises a speed sensor for detecting an actual vehicular speed and a controller. The controller is operable to set a target vehicular speed calculated based on a given turning condition of the vehicle and a lateral acceleration limitation value. The controller is also operable to apply deceleration to the vehicle based on the actual vehicular speed and the target vehicular speed and to correct the deceleration of the vehicle based on information of a curve in a path of the vehicle.
DETAILED DESCRIPTION For known devices and methods for controlling deceleration of vehicles such as that described in Japanese Kokai Patent Application No. Hei 10[1998]-278762 mentioned above, since the allowable level of lateral acceleration as the threshold value for applying deceleration control is preset, the deceleration control may be applied for conditions other than traveling along a curve, such as when changing lanes. This can cause a sense of discomfort in the driver if the deceleration control is applied unnecessarily during travel other than along a curve.
A yaw rate sensor 11 detects a yaw rate φ′ (referred to as measured yaw rate φ′ hereinafter) of the vehicle. A steering angle sensor 12 detects steering angle δ of the steering wheel and outputs the signal to the deceleration controller 10. The wheel speed sensors 13FL, 13FR, 13RL, and 13RR detect the revolving speeds, that is the wheel velocities Vwi(i=FL�RR) of respective wheels 2FL, 2FR, 2RL, and 2RR (collectively, Vw) and outputs the signals to the deceleration controller 10. An accelerator sensor 14 detects depression amount (e.g., opening angle θth) of an accelerator, not shown, and outputs the signal to the deceleration controller 10. A second acceleration sensor 15 detects lateral acceleration Yg generated by the vehicle and outputs the signal to the deceleration controller 10.
As shown in FIG. 2, for example, the deceleration controller 10 is equipped with a yaw rate computation part 21, which computes a selected yaw rate φ* to be used for arithmetic processing based on the steering angle δ sent from the steering angle sensor 12, the vehicle velocities VwFL through VwRR sent from the speed sensors 13FL through 13RR, and the measured yaw rate φ′ sent from the yaw rate sensor 11. The deceleration controller 10 also includes a lateral acceleration limitation value computation part 26, which computes lateral acceleration limitation value Yg*, and a corrective lateral acceleration limitation value computation part 25, which corrects the corrective lateral acceleration value Yg* computed by the lateral acceleration limitation value computation part 26. A target vehicular speed computation part 22 of the deceleration controller 10 computes target vehicular speed V* based on the selected yaw rate φ* from the yaw rate computation part 21, the lateral acceleration limitation value Yg* computed by lateral acceleration limitation value computation part 26, and a road-surface friction coefficient μ. A target deceleration computation part 23 of the deceleration controller 10 computes target deceleration Xg* based on target vehicular speed V*, which is computed by the target vehicular speed computation part 22. Finally, the deceleration controller 10 includes a deceleration control part 24, which drives the brake fluid pressure control unit 1 and the engine throttle control unit 3 so as to realize the target deceleration Xg* computed by the target deceleration computation part 23.
In S2, a yaw rate is computed. Computation of the yaw rate is carried out by yaw rate computation part 21 shown in FIG. 2. As illustrated in FIG. 5, yaw rate computation part 21 is equipped with yaw rate estimation part 31 and yaw rate selection part 32. Yaw rate estimation part 31 estimates a yaw rate φe based on steering angle δ detected by steering angle sensor 12 and wheel velocities Vw detected by wheel speed sensors 13. The estimated yaw rate φe is estimated using a widely used technique based on the steering angle δ and the vehicular speed or wheel velocity. Yaw rate estimation part 31 outputs the estimated yaw rate φe (referred as estimated yaw rate φe hereinafter) to yaw rate selection part 32. Yaw rate selection part 32 performs select-high by selecting the higher value between the estimated yaw rate φe input from yaw rate estimation part 31 and the measured yaw rate φ′ detected by yaw rate sensor 11.
Referring again to FIG. 6, in S23 corrective lateral acceleration limitation value Ygc_HO, which is used to correct lateral acceleration limitation value Yg to be described later, is computed. As shown in FIG. 10, when distance LSTART to the start of the curve is greater than prescribed value LS1 (refer to FIG. 4), that is, when the vehicle is traveling, before reaching the position at prescribed distance LS1 from the start of the curve, corrective lateral acceleration limitation value Ygc_HO is set at prescribed value Ygc. When distance LSTART to the start of the curve decreases below prescribed value LS1, corrective lateral acceleration limitation value Ygc_HO is brought increasingly closer to reference lateral acceleration limitation value Ygc_0, which was set based on correction coefficient KD in S22. The distance LSTART decreases until the start of the curve (LSTART=0) is reached. When the start of the curve (LSTART=0) is passed, corrective lateral acceleration limitation value Ygc_HO is set at reference lateral acceleration limitation value Ygc_0, which was set based on correction coefficient KD in S22.
Ygc � HO=Ygc (1)
Ygc � HO=(Ygc−Ygc �0)/L S1 �L START +Ygc �0 (2)
Ygc � HO=Ygc �0 (3)
Yg*=Ygc � HO+Ygv+Yga (4)
V*=μ�Yg*/φ* (5)
In S6 target deceleration Xg* is computed. The computation is carried out by target deceleration computation part 23 shown in FIG. 2. Target deceleration Xg is computed using equation (6):
Xg*=K�ΔV/Δt (6)
Xg*=(K1�ΔV+K2�dΔV)/Δt (7)
where dΔV indicates the deviation value obtained by subtracting a past value ΔVz of speed deviation ΔV from the current speed deviation ΔV(dΔV=ΔV−ΔVz), and K1 and K2 are prescribed gains.
Acc=Acc � bs (9)
When target deceleration Xg* returns to 0 or lower as the vehicle passes the curve, a transition is made from S32 to S38. Because deceleration control is applied once when Xg*>0, and the deceleration control involvement flag is set to ON, a transition is made to S40 based on the decision made in S38 in order to control the brake fluid pressure so that the pressure is reduced. After the braking control is finished, the throttle opening angle is recovered to the level that corresponds to the accelerator operation amount performed by the driver. When the throttle is fully recovered, deceleration control involvement flag is reset to OFF before ending deceleration control.
In addition, because reference lateral acceleration limitation value Ygc_0 decreases as correction coefficient KD increases (refer to S22 of FIG. 6), deceleration control intervention timing is set forward as correction coefficient KD increases. Then, correction coefficient KD increases as curve value R decreases (refer to S22 of FIG. 6), and the deceleration control intervention timing is set forward as curve value R decreases. The forwarded deceleration control intervention timing also means that cancellation of deceleration control becomes more difficult, and thus easier to maintain. The relationship is summarized below in Table 1:
(i.e. when cancellation of deceleration
control becomes more difficult)
Target deceleration: Xg*
Target vehicular speed: V*
Lateral speed limitation value: Yg*
Corrective lateral acceleration limitation value: Ygc_HO
Reference lateral acceleration limitation value: Ygc_0
As described above, lateral speed limitation value Yg* (and accordingly the corrective lateral acceleration limitation value Ygc_HO) is set based on value R at a prescribed position within the curve, and lateral speed limitation value Yg* decreases as value R of the curve ahead of the vehicle decreases. As a result, deceleration control can be implemented more easily based on value R of the curve.
Velocity-sensitive lateral acceleration correction value Ygv increases as vehicular speed V decreases (refer to FIG. 13). Therefore, the lateral acceleration limitation value Yg* also increases (refer to equation (4)). Target vehicular speed V* is increased in a low-speed area (refer to equation (5)), so that deceleration control becomes harder to apply (refer to equation (6)). The application of deceleration control is made harder while in a low-speed area to reduce driver discomfort from deceleration control being applied while in the low-speed area.
Correction coefficient KD may be set based on the amount of overspeed. For example, as shown in FIG. 19, correction coefficient KD is increased as the amount of overspeed increases, and correction coefficient KD is set at a fixed value once the amount of overspeed has exceeded a certain value. The amount of overspeed refers to the differential value between prescribed vehicular speed V*2 and the current vehicular speed Vi, which is calculated with Vi≧V*2 as a condition. The prescribed vehicular speed V*2 is calculated by:
V* 2=√(Ygc�R) (11)
The prescribed value Ygc is a value used to set lateral acceleration limitation value Yg*. Therefore, the lateral acceleration limitation value Yg* and the amount of overspeed can be set using the same index. For example, assuming that R=100 m and Ygc=0.45 g, the prescribed vehicular speed V*2 is √(0.45�9.8�100)=71 km/h.
Yg � est=Vi 2 /R (12)
Ygc � HO=Ygc �0+ΔYgc�Δt (13)
A revision of lateral acceleration limitation value Yg* based on correction coefficient KD may be canceled when a driving operation is performed by the driver. For example, as shown in FIG. 30, the target vehicular speed V* (=Vc), which is computed by setting corrective lateral acceleration limitation value Ygc_HO at prescribed value Ygc, is faster, and the target vehicular speed V* (=Vc_HO) computed using corrective lateral acceleration limitation value Ygc_HO (Ygc>Ygc_HO≧Ygc_0), which is computed based on correction coefficient KD, is slower than the actual vehicular speed Vi (V). The reference lateral acceleration limitation value Ygc is not corrected based on correction coefficient KD although deceleration control is actually applied (Vi>Vc_HO, ΔV<0). The result is that the target vehicular speed is greater than the actually vehicular speed, Vc>Vi (Xg*<0). When the driver operates the accelerator, accelerating the vehicle, and deceleration control is not applied (the area sandwiched by the dotted lines in FIG. 30), correction of lateral speed limitation value Yg* based on correction coefficient KD is canceled. This occurs, for example, at the end of the curve.
When the accelerator is operated by the driver while deceleration control is in progress, the correction of lateral acceleration limitation value Yg based on correction coefficient KD is canceled, and deceleration control can be applied in conformity with the intent of the driver. For example, even if deceleration control is applied unnecessarily due to a drop in the detection accuracy of the road shape, that is, value R, deceleration control is canceled when the driver accelerates, so that creation of a sense of discomfort in the driver by the deceleration control can be prevented.
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