JP2001260786A - Method for determining vehicle rollover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently increase the accuracy of determining whether or not there is a possibility of vehicle rollover according to the roll angle and roll angular velocity of the vehicle, by taking into account the influence of an external force acting on the position of the center of gravity of the vehicle. SOLUTION: A threshold line S is set on a two-dimensional map whose parameters are the roll angle θ and roll angular velocity ω of the vehicle, and one determines that there is a possibility of vehicle rollover when hysteresis lines of the actual roll angle θ and roll angular velocity ω of the vehicle cross the threshold line S from a non-rollover area on the side of an original point to a rollover area on the side opposite to the original point. If the direction of a gravitational force acting on the position of the center of gravity of the vehicle and the direction of a centrifugal force pass inside of the grounding point of an outer turning wheel, the roll of the vehicle is restrained; if the resultant of the forces passes outside of the grounding point, the roll of the vehicle is promoted. Thus, depending on the direction of the resultant the threshold line S on the map is moved in the direction toward or away from the original point to increase the accuracy of determining whether or not there is a possibility of vehicle rollover.

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]

By the way, the gravity downward in the vertical direction acts on the position of the center of gravity of the vehicle, and when the vehicle turns, a centrifugal force acting outward in the turning direction acts on the position of the center of gravity. Due to the resultant force, a moment is generated with the ground point of the wheel outside the turning direction as a fulcrum. When the centrifugal force is large, the resultant force passes outside the contact point of the wheel, so that a moment is generated around the contact point to promote the rollover of the vehicle, and when the centrifugal force is small, the resultant force is applied to the wheel. , A moment is generated around the contact point to suppress the vehicle from rolling over.

However, in the above-mentioned conventional apparatus, only the rollability of the vehicle is determined using the roll angle and the roll angular velocity of the vehicle as parameters, and the influence of gravity and centrifugal force acting on the vehicle is not taken into account. There has been a problem that the accuracy of determining the possibility cannot be sufficiently increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and is an external force acting on the position of the center of gravity of a vehicle when judging the possibility of the vehicle rolling over based on the roll angle and the roll angular velocity of the vehicle. It is an object of the present invention to sufficiently increase the accuracy of determining the possibility of rollover in consideration of the influence of the above.

[0006]

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 of (1), there is proposed a rollover judging method of the vehicle, wherein the threshold value line is moved based on an external force acting on the position of the center of gravity of the vehicle.

According to the above configuration, the threshold value line is moved based on the external force acting on the position of the center of gravity of the vehicle. Therefore, the roll moment generated based on the external force is taken into consideration to enhance the accuracy of determining the possibility of rollover. be able to.

According to the invention described in claim 2,
In addition to the configuration of the first aspect, a vehicle rollover determination method is proposed, wherein the external force is a combined force of gravity and centrifugal force acting on the position of the center of gravity of the vehicle.

According to the above configuration, it is possible to further improve the accuracy of determining the possibility of rollover in consideration of the influence of the roll moment generated by the combined force of gravity and centrifugal force acting on the position of the center of gravity of the vehicle.

According to the third aspect of the present invention,
In addition to the configuration of claim 1, when the external force acts in a direction that promotes the rollover of the vehicle, the threshold value line is moved to the origin side, and the external force acts in a direction that suppresses the rollover of the vehicle. Proposes a method of determining a rollover of a vehicle, characterized in that the threshold value line is moved to the side opposite to the origin.

According to the above construction, when an external force acting on the position of the center of gravity of the vehicle promotes the rollover of the vehicle, the threshold value line moves to the origin side, and when the external force suppresses the rollover of the vehicle, the threshold is moved. Since the value line moves to the side opposite to the origin, the accuracy of determining the possibility of the vehicle rolling over can be further improved.

[0012]

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.

FIGS. 1 to 8 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 possible rollover 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 an external force acting on a position of a center of gravity. It is a figure explaining the influence on the possibility of rollover.

FIG. 1 shows types of rollover of a 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 judging the possibility of rollover of the vehicle. The positive value (above the origin) of the roll angle θ on the vertical axis is the right roll angle. 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 history line H1 shows the case where the roll angle θ and the roll angular velocity ω are both 0 (origin), and only the roll angle θ is slowly increased while the roll angular velocity ω is almost kept 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 °.

Even if the roll angle θ is 0, the vehicle may roll over if a large roll angular velocity ω acts. 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 the "simple rotation" type such as "flipover", "climbover", "fallover", etc., 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 "divergent" 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, since the roll angle θ converges toward the origin before crossing the threshold value line S, the vehicle does not roll over in this case.

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

An inflator 13 for generating a 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 and a signal from a vertical acceleration sensor 17 that detects a vertical acceleration Gz that is an acceleration in the vehicle vertical direction 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.

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 as described above, the initial value θi is calculated by 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.

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 by 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.

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

First, in step S1, the lateral acceleration Gy and the roll angular velocity ω are read, and in step S2, the lateral acceleration Gy is calculated.
The threshold value lines S on the map are determined according to y.
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 vehicle rolls over due to the lateral acceleration Gy, both the critical roll angle θCRT and the critical roll angular velocity ωCRT decrease, and the threshold lines S, S move in the direction approaching the origin, and the lateral acceleration Gy causes When rollover of the vehicle is suppressed, the critical roll angle θCRT and the critical roll angular velocity ω
The CRT increases together and the threshold value lines S, S move in a direction away from the origin. Thereby, the lateral acceleration G of the vehicle is obtained.
An appropriate rollover area and non-rollover area according to y can be set.

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).

Subsequently, it is determined whether 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 S3, the determination value θ2 is calculated by substituting the current value of the roll angular velocity ω1 into ω in the equation of the threshold value line S. The determination value θ2 is the θ coordinate of the intersection Q between the straight line ω = ω1 and the threshold value line S.
In the following step S4, the judgment value θ2 and the current roll angle θ1
If | θ2 | <| θ1 | holds, the current roll angle θ1 and roll angular velocity ω are determined in step S5.
1 is determined to be in the rollover region, and | θ2
If | <| θ1 | is not satisfied, it is determined in step S6 that the coordinate point P formed by the current roll angle θ1 and roll angular velocity ω1 is in the non-rollover region. FIG. 6 shows a case where the coordinate point P is in the rollover region (| θ2 | <| θ1 |).

As shown in FIG. 8A, if the vehicle is turning left with the roll angle = 0, the gravity center Fg of the vehicle in the vertical direction and the centrifugal force of the horizontal direction in the right direction are located at the center of gravity CG of the vehicle. The force Fh acts. Vehicle roll angle =
In the state of 0, since the vertical direction of the vehicle coincides with the vertical direction, the vertical acceleration Gz detected by the vertical acceleration sensor 17 is obtained.
The vertical force Fz (= m × Gz) obtained by multiplying the vehicle mass m by the vehicle body mass m matches the gravity Fv, and the lateral direction of the vehicle coincides with the horizontal direction. The lateral force Fy multiplied by m (= m × Gy) matches the centrifugal force Fh. In FIG. 8A, the resultant force F of the gravity Fv and the centrifugal force Fh passes through the contact point P of the right wheel, which is the turning outer wheel. The rollover of the vehicle is suppressed by the counterclockwise roll moment described above, and conversely, when the resultant force F passes outside the ground point P, the rollover of the vehicle is promoted by the clockwise roll moment around the ground point P.

However, since the roll angle θ actually occurs when the vehicle is turning, the direction of the gravity Fv and the direction of the centrifugal force Fh acting on the center of gravity CG of the vehicle are changed as shown in FIG. The direction of the vertical force Fz detected by the vertical acceleration sensor 17 and the direction of the lateral force Fy detected by the lateral acceleration sensor 15 are shifted by the roll angle θ. The vertical force Fz and the lateral force y have the following relationship with the gravity Fv, the centrifugal force Fh, and the roll angle θ.

Fz = Fv cos θ−Fh sin θ Fy = Fh cos θ + Fv sin θ As shown in FIG. 8B, the vertical force Fz calculated from the output of the vertical acceleration sensor 17 and the lateral force Fy calculated from the output of the lateral acceleration sensor 15 Is equal to the resultant force F of the gravity Fv and the centrifugal force Fh. Therefore, the roll angle θ of the vehicle
Is not 0, if the resultant force F of the vertical force Fz calculated from the output of the vertical acceleration sensor 17 and the lateral force Fy calculated from the output of the lateral acceleration sensor 15 is obtained, the result is the gravity Fv.
And the resultant force F of the centrifugal force Fh,
If the vehicle passes through the inside of the ground point P of the turning outer wheel, the vehicle rolls over. If the resultant force F passes outside the ground point P, the vehicle rolls over.

As shown in FIG. 6, when the rollover of the vehicle is suppressed by the resultant force F of the gravitational force Fv and the centrifugal force Fh acting on the position CG of the center of gravity of the vehicle, the threshold value S of the map is reduced. It is moved in the direction away from the origin (arrow B direction) to delay the determination of the possibility of rollover, and the resultant force F of the gravity Fv and the centrifugal force Fh acting on the center of gravity CG of the vehicle.
When the rollover of the vehicle is promoted, the threshold value S in the map is moved in the direction approaching the origin (the direction of the arrow A) to accelerate the determination that there is a possibility of rollover, and based on the resultant force F, The rollover possibility determination accuracy can be improved in consideration of the generated roll moment.

As described above, in the present embodiment, the threshold values S, S of the map are moved by the lateral acceleration Gy of the vehicle, and the map is determined based on the gravity Fv and the centrifugal force Fh acting on the center of gravity CG of the vehicle. Since the threshold values S and S are moved, it is possible to accurately determine the possibility of rollover of the vehicle and deploy the air curtain at an appropriate timing.

Although the embodiment of the present invention has 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.

[0045]

As described above, according to the first aspect of the present invention, the threshold value line is moved based on the external force acting on the position of the center of gravity of the vehicle, and therefore, the roll moment generated based on the external force In consideration of the above, it is possible to enhance the accuracy of determining the possibility of rollover.

According to the second aspect of the present invention,
In consideration of the effect of the roll moment generated by the combined force of gravity and centrifugal force acting on the position of the center of gravity of the vehicle, the accuracy of determining the possibility of rollover can be further increased.

According to the invention described in claim 3,
When the external force acting on the position of the center of gravity of the vehicle promotes the rollover of the vehicle, the threshold line moves to the origin side, and when the external force suppresses the rollover of the vehicle, the threshold line moves to the anti-origin side. Therefore, the accuracy of determining the possibility of the vehicle rolling over can be further improved.

[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 a view for explaining the influence of an external force acting on the position of the center of gravity on the possibility of rollover.

[Explanation of Signs] CG center of gravity position F resultant force (external force) Fh centrifugal force Fv gravity S threshold value 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 G01P 15/00 G01P 15/00 J (72) Inventor Osamu Takahata Wako Saitama 1-4-1, Ichichuo F-term in Honda R & D Co., Ltd. (Reference) 3D037 FA21 3D054 AA06 AA07 AA16 DD28 EE09 EE14 EE18 EE20 EE30 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, comprising: moving the threshold value line (S) based on an external force (F) acting on a center of gravity (CG) of the vehicle. 2. The method according to claim 1, wherein the external force (F) is a position of a center of gravity (C) of the vehicle.
The method for determining rollover of a vehicle according to claim 1, wherein the resultant is a resultant force of gravity (Fv) and centrifugal force (Fh) acting on G). 3. When the external force (F) acts in a direction that promotes rollover of the vehicle, the threshold value line (S) is moved to the origin side, and the external force (F) suppresses the rollover of the vehicle. The method according to claim 1, wherein the threshold value line (S) is moved to a side opposite to the origin when acting in the direction.