JP2001260782A - Vehicle rollover judgment method - Google Patents

Abstract

(57) [Summary] To determine the possibility of a vehicle rolling over based on the roll angle and the roll angular velocity of the vehicle, determine the possibility of rollover considering the height of the center of gravity of the vehicle. Increase accuracy. A roll angle θ and a roll angular velocity ω of a vehicle are provided.
The threshold value line S is set on a two-dimensional map with parameters as parameters, and the actual roll angle θ and roll angular velocity ω of the vehicle
When the history line crosses the threshold value line S from the non-rollover area on the origin side to the rollover area on the anti-origin side, it is determined that the vehicle may roll over. When the position of the center of gravity of the vehicle is raised due to the loading of luggage on the roof or the like, the threshold value line S is moved closer to the origin side from the solid line position to the broken line position, so that the history line crosses the new threshold value line S '. This makes it easy to determine that there is a possibility of rollover, so that the performance of the air curtain can be effectively exhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining whether or not a vehicle may roll over based on the roll angle and the roll angular velocity of the vehicle.

[0002]

2. Description of the Related Art On a two-dimensional map using a roll angle and a roll angular velocity of a vehicle as parameters, a rollover area is set at a place where the roll angle and the roll angular velocity are large (an area away from the origin), and a roll angle and a roll angular velocity are set. When a non-rollover area is set in a small area (the area including the origin) and the actual roll angle and roll angular velocity detected by the sensor are plotted on a map, the history line enters the rollover area from the non-rollover area, Japanese Patent Laying-Open No. 7-164985 discloses a technique in which it is determined that there is a possibility that a vehicle rolls over and an active roll bar is raised.

[0003]

However, in the case where a roof carrier is mounted on a vehicle and heavy loads are mounted on the vehicle, the center of gravity of the vehicle is higher than in a normal state. Roll angle θ that does not cause any problem
Alternatively, even if the roll angular velocity ω is generated, the vehicle may roll over. However, the conventional two-dimensional map using the roll angle and the roll angular velocity as parameters is
Since the change in the height of the center of gravity due to the loading of the load is not considered, there is a problem that it is difficult to accurately determine the possibility of rollover.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and determines the height of the center of gravity of a vehicle when determining whether or not the vehicle may roll over based on the roll angle and roll angular velocity of the vehicle. It is an object of the present invention to improve the accuracy of determining the possibility of rollover in consideration of the above.

[0005]

According to the first aspect of the present invention, a threshold value line is set on a two-dimensional map in which a roll angle and a roll angular velocity of a vehicle are used as parameters. A vehicle that determines that the vehicle may roll over when a history line of the actual roll angle and roll angular velocity of the vehicle crosses from a non-rollover region on the origin side of the threshold value line to a rollover region on the anti-origin side. In the rollover judging method, the threshold value line is changed according to the height of the center of gravity of the vehicle.

According to the above configuration, the threshold value line for judging the possibility of rollover of the vehicle is changed according to the height of the center of gravity of the vehicle, so that the influence of the height of the center of gravity on the possibility of rollover is compensated. Thus, an accurate determination can be made.

According to the second aspect of the present invention,
In addition to the configuration of claim 1, the threshold value line is moved to the origin side as the position of the center of gravity of the vehicle increases, and the threshold value line is moved to the side opposite to the origin as the position of the center of gravity of the vehicle decreases. A rollover determination method characterized by causing the rollover is performed.

According to the above configuration, the threshold value line moves to the origin side when the center of gravity of the vehicle increases and the possibility of rollover increases, and the threshold value line decreases when the center of gravity of the vehicle decreases and the rollover possibility decreases. Moves to the side opposite to the origin, so that the influence of the height of the position of the center of gravity on the possibility of rollover can be accurately compensated.

According to the third aspect of the present invention,
In addition to the configuration of the first aspect, there is proposed a rollover determination method for a vehicle, wherein the height of the position of the center of gravity of the vehicle is detected based on the roll state of the vehicle generated according to steering.

According to the above configuration, since the roll state of the vehicle generated according to the steering changes depending on the height of the center of gravity, the height of the center of gravity can be accurately detected based on the roll state.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 9 show an embodiment of the present invention. FIG. 1 is a diagram showing types of rollover of a vehicle, and FIG. 2 is a graph showing roll angles θ and roll angular speeds ω and rollability of the vehicle. FIG. 3 is a diagram for explaining the relationship, FIG. 3 is a map for determining the possibility of rollover of the vehicle, FIG. 4 is a block diagram of a control system of the air curtain, and FIG. 5 shows an initial value θi of the roll angle θ from the lateral acceleration Gy. FIG. 6 is a diagram illustrating a method of determining whether a history line is in a rollover region or a non-rollover region, FIG. 7 is a flowchart illustrating an operation, and FIG. 8 is a diagram illustrating a center-of-gravity height h of a vehicle. FIG. 9 is a diagram illustrating a calculation method, and FIG. 9 is a diagram illustrating a change in the deployment timing of the air curtain depending on the height of the position of the center of gravity.

FIG. 1 shows the types of rollover of the vehicle classified by cause. The types of rollover of the vehicle are classified into “simple rotation”, “simple rotation + sideslip speed” and “divergence” according to the vehicle behavior in the process of rolling over. , "Climbover" and "fallover." A typical rollover of the "simple rotation + skid speed" type is called "tripover", and a typical rollover of the "divergent" type is called "turnover".

"Flipover" is a rollover that occurs when one of the left and right wheels of a vehicle runs over an obstacle. “Climb over” is a rollover that occurs when a vehicle whose tire rises off the road surface while riding on an obstacle at the bottom falls down sideways. “Fallover” is a rollover in which one of the left and right wheels of the vehicle falls off the road shoulder. “Trip over” is a rollover that occurs when a vehicle skids and one of the left and right tires collides with a curb or the like due to a roll moment about the curb as a fulcrum. “Turnover” means that the frequency of the steering wheel operation is changed when the steering wheel is operated left and right alternately to make a double lane change or triple lane change, or to pass an S-shaped road. Is close to the frequency of the natural vibration of the vehicle, the roll angle of the vehicle diverges due to resonance.

FIG. 2 shows a part (first quadrant) of a two-dimensional map for determining the possibility of rollover of the vehicle. The roll angle θ on the vertical axis is a positive value (above the origin) and the right roll angle is The positive value (right side of the origin) of the roll angular velocity ω on the horizontal axis corresponds to the right roll angular velocity. In this two-dimensional map, a threshold value line S composed of a straight line descending to the right is set, and the origin side of the threshold value line S, that is, a region where the roll angle θ and the roll angular velocity ω are small is set as a non-rollover region, Anti-origin side of line S, that is, roll angle θ and roll angular velocity ω
The region where is larger is the rollover region. The history lines H1 to H of the actual roll angle θ and the roll angular velocity ω of the vehicle
When the vehicle crosses the threshold value line S from the non-rollover area on the origin side to the rollover area on the opposite side of the origin, it is determined that there is a possibility of the vehicle rolling over.

The hysteresis line H1 shows a case where only the roll angle θ is slowly increased from the state where both the roll angle θ and the roll angular velocity ω are 0 (origin) while the roll angular velocity ω is kept substantially at 0. At a point a where the value line S intersects the vertical axis, the roll angle θ becomes the critical roll angle θC.
When the vehicle reaches RT, it is determined that there is a possibility of the vehicle rolling over. At this time, the center of gravity CG of the vehicle is on a vertical line passing through the tire on the outer side in the roll direction, which is a fulcrum of rolling, and this state is a static stability limit for rollover of the vehicle.
The value of the critical roll angle θCRT varies depending on the shape of the vehicle and the loading state, but is generally about 50 °.

Incidentally, even if the roll angle θ is 0, the vehicle may roll over if a large roll angular velocity ω is acting. At this time, the roll angular velocity ω is changed to the critical roll angular velocity ω
CRT.

When the vehicle has a roll angular velocity ω in the same direction as the direction of the roll angle θ, rollover is promoted by the roll angular velocity ω.
Rollover will occur even in a state smaller than RT. For example, when the history line of the roll angle θ and the roll angular velocity ω is indicated by H2, it is determined that the vehicle may roll over at a point b where the history line H2 crosses the threshold value line S from the origin side to the anti-origin side. . The roll angle θ at this time is a value smaller than the critical roll angle θCRT.

When the history line of the roll angle θ and the roll angular velocity ω is indicated by H3, the positive value of the roll angular velocity ω quickly changes from increasing to decreasing, and further shifts to a negative value. Does not cross the threshold value line S, and therefore it is determined that there is no possibility of the vehicle rolling over.

FIG. 3 shows the entire two-dimensional map for determining the possibility of rollover of the vehicle. The two threshold lines S, S are set in the first and third quadrants, and the threshold lines S, S are point-symmetric with respect to the origin in the initial setting state. The rollover area is not set in the second quadrant where the roll angle θ is positive and the roll angular velocity ω is negative, and the fourth quadrant where the roll angle θ is negative and the roll angular velocity ω is positive. This is because the rollover of the vehicle does not occur when the roll angular velocity ω in the direction opposite to the direction is generated.

FIG. 3 shows history lines H4 to H8 of the roll angle θ and the roll angular velocity ω corresponding to the various types of rollover described with reference to FIG.

The history line H4 corresponds to a rollover of a "simple rotation" type such as "flipover", "climbover", or "fallover", and the roll angle θ
And the absolute value of the roll angular velocity ω simply increase, and the rollover occurs.

The history line H5 indicates "trip over".
This corresponds to a rollover of the “simple rotation + skid speed” type, and the roll angular velocity ω is generated by the roll moment generated when the tire collides with a curb or the like in the process of skidding the vehicle.
Has increased sharply, leading to a rollover.

The history lines H6 and H7 correspond to a "divergence" type rollover called "turnover". The history line H6 indicates a rollover in a double lane change, and the absolute value of the roll angle θ diverges in the process in which a vehicle that has rolled to the right in the first lane change rolls to the left in the next lane change. Has crossed over the threshold value line S. The history line H7 indicates a rollover in a triple lane change, in which a vehicle that rolls right in the first lane change rolls left in the next lane change and rolls right again in the subsequent lane change. Diverges and crosses over the threshold line S in the first quadrant.

In the history line H8, the roll angle θ converges toward the origin before crossing the threshold value line S. In this case, the vehicle does not roll over.

FIG. 4 shows an example of a control system for deploying an air curtain for protecting the occupant's head when the vehicle rolls over along the inner side surface of the passenger compartment.

An inflator 13 for generating high-pressure gas for deploying an air curtain and an ignition transistor 14 are connected in series between the battery 11 and the grounding section 12. When the ignition transistor 14 is turned on by a command from the electronic control unit U, the inflator 13 is ignited to generate high-pressure gas, and the air curtain supplied with the high-pressure gas is developed along the inner surface of the vehicle interior. In order to determine the possibility of the vehicle rolling over, the electronic control unit U includes a signal from a lateral acceleration sensor 15 for detecting a lateral acceleration Gy, which is an acceleration in the lateral direction of the vehicle, and a roll for detecting a roll angular velocity ω of the vehicle. A signal from the angular velocity sensor 16, a signal from the vehicle speed sensor 17 for detecting the vehicle speed V, and a signal from the steering angle sensor 18 for detecting the steering angle δ of the steering wheel are input.

As shown in FIGS. 4 and 5, the lateral acceleration sensor 15 fixed to the vehicle body has an ignition switch set to O.
The lateral acceleration Gy at the time of N is output. When the ignition switch is turned on, the vehicle is in a stopped state, so that only the lateral component of the gravitational acceleration G = 1 in the vehicle lateral direction is detected as the lateral acceleration Gy without detecting the lateral acceleration caused by the centrifugal force accompanying the turning of the vehicle. I do. Therefore, the lateral acceleration G
y, an initial value θi of the roll angle θ of the vehicle is defined as θi =
It can be calculated by sin ^-1 Gy.

As described above, when the initial value θi of the roll angle θ of the vehicle is calculated based on the output of the lateral acceleration sensor 15 when the ignition switch is turned on, the initial value θi is calculated by the variation of the roll angle θ. Is added to calculate the roll angle θ of the vehicle. That is, from the time when the ignition switch is turned on, the integral value ∫ωdt of the roll angular velocity ω output from the roll angular velocity sensor 16 is changed to the roll angle θ.
Is added to the initial value θi as a variation of
The roll angle θ of the vehicle is calculated.

The lateral acceleration sensor 15 cannot detect the lateral acceleration Gy at the time of free fall of the vehicle, and calculates the lateral acceleration caused by the centrifugal force accompanying the turning of the vehicle as the lateral acceleration which is a component of the gravitational acceleration G in the lateral direction of the vehicle body. There is a disadvantage that the lateral acceleration Gy output from the lateral acceleration sensor 15 is calculated only for calculating the initial value θi of the roll angle θ of the vehicle at the time when the ignition switch is turned on, although it has a disadvantage that it cannot be identified as Gy and is erroneously detected. By using the integrated value ∫ωdt of the roll angular velocity ω output from the roll angular velocity sensor 16 for the calculation of the roll angle θ of the vehicle thereafter, the above-mentioned disadvantages can be solved and the accurate roll angle θ can be calculated. Can be.

Incidentally, the magnitude of the possibility of rollover of the vehicle changes according to the height of the center of gravity CG. FIG. 8A shows a vehicle in which the center of gravity CG is low because no load is loaded on the roof, and FIG. 8B shows a state in which the center of gravity CG is high because load is loaded on the roof. Is shown. When both vehicles are turning at the same speed and the same turning radius, the roll angle θ is the center of gravity position CG in FIG.
The higher the vehicle, the larger. The reason is that the center of gravity C
This is because, when centrifugal force due to the turn acts on G, the vehicle having a higher center of gravity CG has a larger roll moment because the distance from the roll center to the point of application of centrifugal force (that is, the center of gravity CG) is larger. .

The electronic control unit U calculates the height of the center of gravity CG of the vehicle based on the vehicle speed V detected by the vehicle speed sensor 17 and the steering angle δ detected by the steering angle sensor 18.
Specifically, a roll angle θ when the vehicle is making a steady turn at a predetermined vehicle speed V and a steering angle δ is detected, and the roll angle θ is applied to a two-dimensional map using the vehicle speed V and the steering angle δ as parameters. By doing so, the height h of the center of gravity position CG of the vehicle can be searched on a map. Alternatively, a roll angular velocity ω when a vehicle running straight at a vehicle speed V performs steering at a predetermined steering angular velocity dδ / dt is detected, and a two-dimensional map using the vehicle speed V and the steering angular velocity dδ / dt as parameters is obtained. By applying the roll angular velocity ω, the height h of the center of gravity CG of the vehicle can be searched on a map.

The height at which the center of gravity CG of the vehicle becomes the lowest is defined as the reference center of gravity height hmin, and the rollover region and the non-rollover region are determined in accordance with the deviation h-hmin between the detected center of gravity height h and the reference center of gravity height hmin. The threshold value line S that partitions the rollover area,
S is moved to the side approaching the origin.

A history line which is a locus of coordinate points formed by the roll angle θ of the vehicle calculated as described above and the roll angular velocity ω output from the roll angular velocity sensor 16 is shown on the map shown in FIG. When the history line crosses the threshold value lines S, S from the origin side to the anti-origin side, it is determined that the vehicle may roll over, and the ignition transistor 1
4 is turned on to ignite the inflator 13 of the air curtain. At this time, as the center of gravity CG of the vehicle increases, the threshold value lines S, S move to the side approaching the origin, so that the history line can easily cross the threshold value lines S, S, and there is a possibility of rollover. The determination can be made earlier.

The above operation will be further described with reference to FIGS.

First, in step S1, the lateral acceleration Gy, the roll angular velocity ω, the vehicle speed V, and the steering angle δ are read, and in step S2, the threshold value lines S, S on the map are temporarily set according to the lateral acceleration Gy. The threshold value lines S, S are determined when the critical roll angle θCRT, which is the intercept of the vertical axis of the map, and the critical roll angular velocity ωCRT, which is the intercept of the horizontal axis, are determined. In this embodiment, when the rollover of the vehicle is promoted by the lateral acceleration Gy, both the critical roll angle θCRT and the critical roll angular velocity ωCRT decrease, and the threshold lines S, S
Moves in the direction approaching the origin and the rollover of the vehicle is suppressed by the lateral acceleration Gy, the critical roll angle θCRT
And the critical roll angular velocity ωCRT both increase, and the threshold value lines S, S move in a direction away from the origin. Thereby, it is possible to set an appropriate rollover region and a non-rollover region in accordance with the lateral acceleration Gy of the vehicle.

When the threshold value line S in the first quadrant moves in a direction away from the origin, the threshold value line S in the third quadrant moves in a direction approaching the origin, and the threshold value line S in the first quadrant moves to the origin. When moving in the approaching direction, the threshold value line S in the third quadrant moves in the direction away from the origin.

Once the critical roll angle θCRT and the critical roll angular velocity ωCRT are determined, the equation for the threshold lines S, S is given by θ = − (θCRT / ωCRT) ω ± θCRT (see FIG. 3).

In the following step S3, the height of the center of gravity h of the vehicle is calculated based on the vehicle speed V, the steering angle δ, and the roll angle θ (or the roll angular speed ω). In step S4, the height of the center of gravity h and the reference height of the center of gravity are calculated. The threshold value lines S, S that separate the rollover region and the non-rollover region are moved to the side closer to the origin in accordance with the deviation h−hmin from the hmin. This allows
The positions of the threshold value lines S, S according to the height h of the center of gravity are finally determined.

Subsequently, it is determined whether or not the coordinate point P defined by the current roll angle θ1 and roll angular velocity ω1 is in a rollover area or a non-rollover area. That is, in step S5, the determination value θ2 is calculated by substituting the current value of the roll angular velocity ω1 into ω of the equation of the threshold value line S finally determined. The judgment value θ2 is θ at the intersection Q between the straight line ω = ω1 and the threshold value line S.
Coordinates. In the following step S6, the judgment value θ2 is compared with the current roll angle θ1, and if | θ2 | <| θ1 | is satisfied, the coordinate point P formed by the current roll angle θ1 and the roll angular velocity ω1 is satisfied in step S7. Is determined to be in the rollover area, and if | θ2 | <| θ1 | does not hold, it is determined in step S8 that the coordinate point P formed by the current roll angle θ1 and roll angular velocity ω1 is in the non-rollover area. FIG. 6 shows a case where the coordinate point P is in the rollover region (| θ2 | <| θ1
|) Are indicated.

FIG. 9 shows a change in the deployment timing of the air curtain according to the height of the center of gravity of the vehicle. When the center of gravity of the vehicle is low (normal time), a threshold value line S indicated by a solid line is set. The vehicle history line shown by the solid line is R1
Then, the air curtain is deployed across the threshold value line S. On the other hand, when the position of the center of gravity of the vehicle is high, a threshold value line S 'shown by a broken line is set, and the history line of the vehicle shown by the broken line crosses the threshold value line S' at R2, and the air curtain is deployed. As described above, when the vehicle is likely to roll over due to the high center of gravity of the vehicle, it is possible to perform the determination of the possibility of the rollover earlier and to effectively exert the performance of the air curtain.

Although the embodiments of the present invention have been described above, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, the determination of the possibility of the vehicle rolling over is applied to the deployment control of the air curtain.
It can be applied to other uses such as deployment control of the side airbag and deployment control of the retractable roll bar. Further, an initial value θi of the roll angle θ of the vehicle is calculated by using a vertical acceleration Gz which is a component of the gravitational acceleration G in a vehicle vertical direction, θi =
It can be calculated by cos ^-1 Gz.

[0044]

As described above, according to the first aspect of the present invention, the threshold value line for judging the possibility of rollover of the vehicle is changed in accordance with the height of the center of gravity of the vehicle. The influence of the height on the possibility of rollover can be compensated for to make an accurate determination.

According to the second aspect of the present invention,
When the center of gravity of the vehicle increases and the rollover probability increases, the threshold value line moves to the origin side, and when the vehicle's center of gravity decreases and the rollover possibility decreases, the threshold value line moves to the anti-origin side, The influence of the height of the position of the center of gravity on the possibility of rollover can be accurately compensated.

According to the third aspect of the present invention,
Since the roll state of the vehicle generated according to the steering changes according to the height of the position of the center of gravity, the height of the position of the center of gravity can be accurately detected based on the roll state.

[Brief description of the drawings]

FIG. 1 is a diagram showing types of rollover of a vehicle.

FIG. 2 is a diagram illustrating a relationship between a roll angle θ and a roll angular velocity ω and a possibility of rollover of a vehicle.

FIG. 3 is a map for determining the possibility of rollover of the vehicle.

FIG. 4 is a block diagram of a control system of the air curtain.

FIG. 5 is an explanatory diagram of a method for calculating an initial value θi of a roll angle θ from a lateral acceleration degree Gy.

FIG. 6 is a diagram showing a method of determining whether a history line is in a rollover area or a non-rollover area.

FIG. 7 is a flowchart illustrating an operation.

FIG. 8 is an explanatory diagram of a method of calculating a height h of the center of gravity of the vehicle.

FIG. 9 is a diagram illustrating a change in the deployment timing of the air curtain depending on the height of the position of the center of gravity.

[Explanation of symbols]

 CG Center of gravity position h Height of center of gravity position S Threshold line θ Roll angle ω Roll angular velocity

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B60R 21/32 B60R 21/32 (72) Inventor Osamu Takahata 1-4-1 Chuo, Wako-shi, Saitama Stock F-term in Honda R & D Co., Ltd. (reference) 3D037 FA21 3D054 AA06 AA07 AA16 DD28 EE09 EE14 EE15 EE20 EE27 FF20

Claims (3)

[Claims] 1. A threshold value line (S) is set on a two-dimensional map having parameters of a roll angle (θ) and a roll angular velocity (ω) of a vehicle, and the actual roll angle (θ) and roll angular velocity ( ω) when the history line of the threshold value line (S) crosses from the non-rollover region on the origin side of the threshold value line (S) to the rollover region on the anti-origin side, and it is determined that there is a possibility that the vehicle rolls over. A method of determining rollover of a vehicle, wherein the threshold value line (S) is changed according to the height (h) of the center of gravity (CG) of the vehicle. 2. The threshold value line (S) is moved to the origin side as the center of gravity (CG) of the vehicle increases, and the threshold value line (S) is shifted as the center of gravity (CG) of the vehicle decreases. The method according to claim 1, wherein S) is moved to a side opposite to the origin. 3. The vehicle rollover determination according to claim 1, wherein a height (h) of a center of gravity (CG) of the vehicle is detected based on a roll state of the vehicle generated according to steering. Method.