JP2001071787A - Vehicle rollover judgment method - Google Patents

Abstract

(57) [Summary] To determine whether or not a vehicle may roll over based on a roll angle and a roll angular velocity of the vehicle, the determination accuracy is further improved. 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 steering angle δ of the vehicle acts in a direction that promotes rollover of the vehicle, the threshold line S
Is moved in a direction approaching the origin, and when the steering angle δ of the vehicle acts in a direction to suppress the rollover of the vehicle, the threshold line S is moved in a direction away from the origin.

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]

The main parameters governing the possibility of the vehicle rolling over are the roll angle and the roll angular velocity, but there are other parameters that promote or suppress the vehicle rollover. Exists.
For example, even if the roll angle and the roll angular velocity of the vehicle are the same, the magnitude of the rollover greatly differs depending on the steering angle of the vehicle. Specifically, when the steering wheel is steered to the left, the vehicle rolls to the right, and when the steering wheel is steered to the right, the vehicle rolls to the left. Steering to the left increases the rollover of the vehicle to the right, and steering the steering wheel to the right while the vehicle rolls to the left increases the rollover of the vehicle to the left.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and further improves the accuracy of determining whether or not the vehicle may roll over based on the roll angle and roll angular velocity of the vehicle. With the goal.

[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 rollover determination method for a vehicle that determines that the vehicle may roll over when the history line of the actual roll angle and roll angular velocity of the vehicle crosses the threshold value line from the origin side to the anti-origin side, A method of judging a rollover of a vehicle, characterized in that a threshold value line is changed in accordance with a change direction of a steering angle of the vehicle.

According to the above configuration, the threshold value line set on the two-dimensional map using the roll angle and the roll angular velocity of the vehicle as parameters changes according to the direction in which the steering angle of the vehicle changes. A more accurate determination can be made by compensating for a change in rollover possibility that changes depending on the change direction.

According to the second aspect of the present invention,
In addition to the configuration of claim 1, when the change direction of the steering angle is a direction that increases the absolute value of the roll angle of the vehicle, the threshold value line is moved to the origin side, and the absolute value of the roll angle of the vehicle is changed. There is proposed a method of judging rollover of a vehicle, characterized in that the threshold value line is moved to the side opposite to the origin when the direction is to decrease.

According to the above configuration, the threshold value line moves toward the origin when the change direction of the steering angle of the vehicle is a direction in which the absolute value of the roll angle is increased, so that the actual roll angle and the roll angular velocity of the vehicle are changed. Can easily cross the threshold value line from the origin side to the anti-origin side, and the possibility of rollover can be determined earlier. Conversely, when the change direction of the steering angle of the vehicle is a direction that decreases the absolute value of the roll angle, the threshold value line moves to the opposite side of the origin, so that the history lines of the actual roll angle and the roll angular velocity of the vehicle include the threshold value. It is difficult to cross the value line from the origin side to the anti-origin side, so that the possibility of rollover can be more accurately determined.

[0009]

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 7 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 inflatable curtain, and FIG. 5 is an initial value θ _{0 of the} roll angle θ from the lateral acceleration Gy. FIG. 6 is a diagram illustrating the movement of a threshold value line based on the steering angle δ, and FIG. 7 is a flowchart illustrating the operation.

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 + lateral speed”, and “divergence” according to the vehicle behavior in the process leading to rollover. , "Climbover" and "fallover."
A typical rollover of the "simple rotation + lateral speed" type is called "tripover", and a typical rollover of the "divergent" type is called "turnover".

[0012] "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 that occurs when one of the left and right wheels of the vehicle steps off the shoulder of the road. “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. And history lines H _{1 to} H ₁ of the actual roll angle θ and roll angular velocity ω of the vehicle.
_{When 3} 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 H ₁ shows a case where only the roll angle θ is slowly increased from the state in which both the roll angle θ and the roll angular velocity ω are 0 (origin) and the roll angular velocity ω is kept at 0. When the roll angle θ reaches the critical roll angle θ _CRT at point a, which is an intercept where the value line S intersects the vertical axis, 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 θ _CRT varies depending on the shape of the vehicle and the loaded state, but is generally about 50 °.

Note that even if the roll angle θ is 0, a large
If the wheel angular velocity ω is acting, the vehicle may roll over
is there. At this time, the roll angular velocity ω is changed to the critical roll angular velocity ω
_CRT And

When the vehicle has a roll angular velocity ω in the same direction as the direction of the roll angle θ, the roll angle is promoted by the roll angular velocity ω.
Rollover will occur even in a state smaller than the _CRT . For example, determining if a rollover possibility of the vehicle at the point b the history line H ₂ crosses the threshold line S from the origin side opposite home side there is the history line of the roll angle θ and the roll angular velocity ω is indicated with H ₂ Is done. At this time, the roll angle θ is a value smaller than the critical roll angle θ _CRT .

When the history line of the roll angle θ and the roll angular velocity ω is indicated by H ₃ , the positive value of the roll angular velocity ω quickly changes from increasing to decreasing, and further shifts to a negative value. It is determined that H ₃ does not cross the threshold value line S, and thus 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 quadrant and the third quadrant, respectively, and these threshold lines S, S are point-symmetric with respect to the origin. 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 H _{4 to} H _{8 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 H ₄ corresponds to a “simple rotation” type rollover such as “flipover”, “climbover”, “fallover”, and the roll angle θ.
And the absolute value of the roll angular velocity ω simply increase, and the rollover occurs.

[0021] The history line H ₅ is, "trip over"
This corresponds to the rollover of the "simple rotation + lateral speed" type, in which the roll angular velocity ω suddenly increases due to the roll moment generated when the tire collides with a curb or the like in the process of skidding, and the rollover occurs. .

The history lines H ₆ and H ₇ correspond to a “divergent” type rollover called “turnover”. History line H ₆ is shows a roll in a double lane change, roll the vehicle to the right in the first lane change is an absolute value diverges roll angle θ in the course of the roll to the left in the next lane change, third It has rolled over the threshold line S in the quadrant. History line H ₇ is shows the rollover triple lane change, the roll angle in the course of vehicle roll to the right in the first lane change is rolled to the left in the next lane change, roll again right in the subsequent lane change The absolute value of θ has diverged, and has rolled over the threshold value line S in the first quadrant.

In the history line H ₈ , the roll angle θ converges toward the origin before crossing the threshold value line S, so that the vehicle does not roll over in this case.

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

Between the battery 11 and the grounding section 12, an inflator 13 for generating a high-pressure gas for expanding the inflatable curtain and an ignition transistor 14 are connected in series. 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 inflatable curtain supplied with the high-pressure gas expands along the inner side surface of the vehicle compartment. The electronic control unit U includes a lateral acceleration G, which is an acceleration in the lateral direction of the vehicle body, in order to determine whether the vehicle can roll over.
A signal from a lateral acceleration sensor 15 for detecting y and a signal from a roll angular velocity sensor 16 for detecting a roll angular velocity ω of the vehicle are input.

As shown in FIG. 5, a lateral acceleration sensor 15 fixed to the vehicle body outputs a lateral acceleration Gy when an ignition switch is turned on. When the ignition switch is turned on, the vehicle is in a stopped state. Therefore, only the lateral component of the gravitational acceleration G 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. Therefore, using the lateral acceleration Gy, the initial value θ ₀ of the roll angle θ of the vehicle can be calculated from θ ₀ = sin ⁻¹ Gy.

[0027] Initial values theta ₀ of the roll angle theta of the vehicle is calculated based on the output of the lateral acceleration sensor 15 when the ON the ignition switch in the manner described above, the roll angle theta to the initial value theta ₀ The roll angle θ of the vehicle is calculated by adding the variation. 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.
By adding to the initial value θ ₀ 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 at the time when the ignition switch is turned on, and the initial value θ ₀ of the roll angle θ of the vehicle is calculated when the ignition switch is turned on. Then, by using the integrated value ∫ωdt of the roll angular velocity ω output by the roll angular velocity sensor 16 for the calculation of the roll angle θ of the vehicle thereafter, the above-mentioned disadvantages are eliminated and the accurate roll angle θ is calculated. be able to.

A history line as 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 inflatable curtain.

When the steering wheel is steered leftward, the vehicle body rolls rightward due to centrifugal force. Conversely, when the steering wheel is steered rightward, the vehicle body rolls leftward due to centrifugal force. The magnitude of the centrifugal force generated at this time increases as the turning radius of the vehicle decreases, and increases as the vehicle speed increases. Therefore, when the roll angle θ and the roll angular velocity ω of the vehicle are in the first quadrant of FIG. 3 and the vehicle may roll to the right, turning the steering wheel to the left may increase rollover. There is. Conversely, the roll angle θ and roll angular velocity ω of the vehicle are shown in FIG.
In the third quadrant, there is a possibility that the vehicle may roll to the left, and turning the steering wheel to the right may increase the rollover.

Therefore, the changing direction of the steering angle δ detected by the steering angle sensor 17 (that is, the sign of the time differential value of the steering angle δ)
Is the direction in which the absolute value of the roll angle θ of the vehicle increases, that is, when the roll angle θ is positive (rightward), the steering angle change rate dδ / dt is negative (the steering angle δ increases to the left). When the roll angle θ is negative (leftward) and the steering angle change rate dδ / dt is positive (the steering angle δ increases rightward) when the roll angle θ is negative (leftward), as shown by an arrow A in FIG. , The threshold value lines S, S are moved in a direction approaching the origin. As a result, the history lines of the roll angle θ and the roll angular velocity ω can easily cross the threshold value lines S, S, and it is possible to more accurately determine the possibility of rollover in consideration of the changing direction of the steering angle δ of the vehicle. Become.

On the other hand, when the detected steering angle δ acts to reduce the absolute value of the roll angle θ of the vehicle, that is, when the roll angle θ is positive (rightward), the steering angle change rate d
When δ / dt is positive (steering angle δ increases rightward) and when roll angle θ is negative (leftward), steering angle change rate dδ / dt is negative (steering angle δ ), The threshold value line S, S is moved in a direction away from the origin to make it difficult for the history line to cross the threshold value line S, S, and a change in the lateral steering angle δ of the vehicle. It is possible to more accurately determine the possibility of rollover in consideration of the direction. In any of the above cases, the movement amount of the history line is set according to the magnitude of the detected lateral steering angle change rate dδ / dt.

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

First, in step S1, the lateral acceleration Gy, the roll angular velocity ω, and the steering angle δ are read, and in step S2, the threshold value lines S, S on the map are determined according to the lateral acceleration Gy. The threshold value lines S, S are determined when the critical roll angle θ _{CRT as} the intercept on the vertical axis of the map and the critical roll angular velocity ω _{CRT as} the intercept on the horizontal axis are determined. In this embodiment, when the rollover of the vehicle is promoted by the lateral acceleration Gy, the critical roll angle θ _CRT and the critical roll angular velocity ω _CRT are both reduced, and the threshold value lines S, S are set so as to approach the origin.

Critical roll angle θ_CRTAnd critical roll angular velocity
Degree ω_CRTIs determined, the equation for the threshold value lines S, S is: θ = − (θ_CRT/ Ω_CRT) Ω ± θ_CRT  (See FIG. 3).

In the following step S3, the steering angle δ is differentiated for steering.
The steering angular velocity dδ / dt is calculated. In the next step S4
The ratio of the sign of the steering angle θ to the sign of the steering angular velocity dδ / dt
And the sign of the steering angle θ and the sign of the steering angular velocity dδ / dt
Are different, steering will help the vehicle roll over.
And in step S5, step S2
Move the threshold value lines S, S determined in
Move. Specifically, the critical roll angle θ_CRTIs α
New critical roll angle θ_CRTSet and critical
Roll angular velocity ω_CRTIs reduced by β and a new critical law
Angular velocity ω_CRT Setting a new threshold value
In S, S are set.

Conversely, if the sign of the steering angle θ and the sign of the steering angular velocity dδ / dt match in step S4, it is determined that the vehicle is prevented from rolling over due to steering. The threshold value lines S, S determined in S2 are moved in a direction away from the origin. Specifically, the critical roll angle θ _CRT is increased by α to set a new critical roll angle θ _CRT , and the critical roll angular velocity ω
New critical roll angular velocity ω _CRT by increasing _CRT by β
Are set, new threshold value lines S, S are set.

Subsequently, the current roll angle θ₁And roll
Angular velocity ω₁The coordinate point P formed in the rollover area or non-rollover
To determine if it is That is, in step S7,
The current roll angular velocity ω is added to ω in the equation of the threshold line S.₁of
Substitute the value and judge value θ_TwoIs calculated. Judgment value θ_TwoIs a straight line
ω = ω₁Is the θ coordinate of the intersection Q of the threshold value line S with the threshold value line S.
In the following step S8, the judgment value θ_TwoAnd the current roll angle θ₁
And |_Two| <| Θ₁If | is true,
In step S9, the current roll angle θ₁And roll angular velocity ω
₁Is determined to be in the rollover region, and | θ_Two
| <| Θ₁If | does not hold, the current
Roll angle θ₁And roll angular velocity ω₁ Coordinate point P
Is determined to be in the non-rollover region. FIG. 6 shows a coordinate point P
Is in the rollover region (| θ_Two| <| Θ₁|) Is indicated
ing.

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 rollover of the vehicle is applied to the deployment control of the inflatable curtain, but this is applied to other controls such as the deployment control of the side airbag and the deployment control of the retractable roll bar. Can be applied to applications. Further, the initial value θ ₀ of the roll angle θ of the vehicle can be calculated by θ ₀ = cos ⁻¹ Gz using the vertical acceleration Gz which is a component of the gravity acceleration G in the vehicle vertical direction.

[0041]

As described above, according to the first aspect of the present invention, the threshold value line set on the two-dimensional map using the roll angle and the roll angular velocity of the vehicle as parameters serves as the changing direction of the steering angle of the vehicle. Therefore, a more accurate determination can be made by compensating for a change in the possibility of rollover that changes according to the direction of change in the steering angle of the vehicle.

According to the second aspect of the present invention,
When the change direction of the vehicle steering angle is a direction that increases the absolute value of the roll angle, the threshold value line moves to the origin side, so the history line of the actual roll angle and roll angular velocity of the vehicle is based on the threshold value line. It is easy to cross from the side to the side opposite to the origin, and it is possible to quickly determine that there is a possibility of rollover.
Conversely, when the change direction of the steering angle of the vehicle is a direction that decreases the absolute value of the roll angle, the threshold value line moves to the opposite side of the origin, so that the history lines of the actual roll angle and the roll angular velocity of the vehicle include the threshold value. It is difficult to cross the value line from the origin side to the anti-origin side, so that the possibility of rollover can be more accurately determined.

[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 inflatable curtain.

FIG. 5 is an explanatory diagram of a method of calculating an initial value θ ₀ of a roll angle θ from a lateral acceleration Gy.

FIG. 6 is a diagram illustrating movement of a threshold value line based on a steering angle δ.

FIG. 7 is a flowchart illustrating an operation.

[Explanation of symbols]

 S threshold value line δ steering angle θ roll angle ω roll angular velocity

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission Date] April 7, 2000 (200.4.7)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

Continued on the front page (72) Inventor Osamu Takahata 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3D037 FA06 FA23 FA26

Claims (2)

[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 vehicle crosses the threshold value line (S) from the origin side to the anti-origin side to determine that there is a possibility that the vehicle rolls over. The threshold value line (S) Is changed according to the change direction of the steering angle (δ) of the vehicle. 2. When the change direction of the steering angle (δ) is a direction that increases the absolute value of the roll angle (θ) of the vehicle, the threshold value line (S) is moved to the origin side to roll the vehicle. The method according to claim 1, wherein the threshold value line (S) is moved to a side opposite to the origin when the absolute value of the angle (θ) is decreased.