JP3875449B2 - Vehicle rollover judgment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is based on the roll angle and roll angular velocity of the vehicle, to a method for determining whether a possibility of the vehicle rollover is there.
[0002]
[Prior art]
On a two-dimensional map with the roll angle and roll angular velocity of the vehicle as parameters, a rollover region is set where the roll angle and roll angular velocity are large (region away from the origin), and where the roll angle and roll angular velocity are small (origin) The vehicle can roll over when a non-rollover area is set in the area and the history line in which the actual roll angle and roll angular velocity detected by the sensor are plotted on the map enters the rollover area from the non-rollover area. Japanese Patent Application Laid-Open No. 7-164985 discloses that an active roll bar is raised when it is determined that there is a property.
[0003]
[Problems to be solved by the invention]
By the way, vertical downward gravity acts on the center of gravity position of the vehicle, and when the vehicle turns, centrifugal force outward in the turning direction acts on the center of gravity position. A moment is generated with the contact point of When the centrifugal force is large, the resultant force passes outside the ground contact point of the wheel, so that a moment is generated around the ground contact point that promotes vehicle rollover. When the centrifugal force is small, the resultant force is applied to the wheel. Therefore, a moment is generated around the grounding point that suppresses vehicle rollover.
[0004]
However, the above-mentioned conventional system only determines the rollover possibility of the vehicle using the roll angle and roll angular velocity of the vehicle as parameters, and does not consider the influence of gravity and centrifugal force acting on the vehicle. There was a problem that the determination accuracy could not be sufficiently increased.
[0005]
The present invention has been made in view of the above circumstances, and an external force acting on the position of the center of gravity of the vehicle when determining whether or not the vehicle may roll over based on the roll angle and the roll angular velocity of the vehicle. The purpose is to sufficiently improve the accuracy of rollover possibility determination.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the invention described in claim 1, a threshold line is set on a two-dimensional map using the roll angle and roll angular velocity of the vehicle as parameters, and the actual roll angle of the vehicle and in the rollover determination method for a vehicle determines that a possibility exists that the vehicle rolls over when the history line of the roll angular velocity is across the threshold line from a non-rollover region of origin side of it to the rollover area of the opposite home side, vehicle based on the external force acting in the gravity center position, the rollover judgment method for a vehicle, characterized in that moving the threshold line in a direction away from the direction or origin approaching the origin is proposed.
[0007]
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, it is possible to improve the rollover possibility determination accuracy in consideration of the roll moment generated based on the external force. .
[0008]
According to a second aspect of the present invention, in addition to the configuration of the first aspect, the external force is a resultant force of gravity and centrifugal force acting on the position of the center of gravity of the vehicle. Is proposed.
[0009]
According to the above configuration, the rollover possibility determination accuracy can be further increased in consideration of the influence of the roll moment generated by the resultant force of gravity and centrifugal force acting on the position of the center of gravity of the vehicle.
[0010]
According to the invention described in claim 3, in addition to the configuration of claim 1, when the external force acts in a direction that promotes vehicle rollover, the threshold line is moved to the origin side, A vehicle rollover judging method is proposed, in which when the external force acts in a direction to suppress the rollover of the vehicle, the threshold value line is moved to the non-origin side.
[0011]
According to the above configuration, the threshold value line moves to the origin side when the external force acting on the center of gravity position of the vehicle promotes the vehicle rollover, and when the external force suppresses the vehicle rollover, the threshold value line is Since it moves to the non-origin side, it is possible to further improve the determination accuracy of the vehicle rollover possibility.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0013]
1 to 8 show an embodiment of the present invention. FIG. 1 is a diagram showing types of rollover of a vehicle. FIG. 2 is a diagram for explaining the relationship between the roll angle .theta. And the roll angular velocity .omega. FIG. 3 is a map for determining whether or not the vehicle can roll over, FIG. 4 is a block diagram of an air curtain control system, and FIG. 5 is a method of calculating an initial value θi of the roll angle θ from the lateral acceleration Gy. FIG. 6 is a diagram showing a method for determining whether a history line is in a rollover region or a non-rollover region, FIG. 7 is a flowchart for explaining the action, and FIG. 8 is a rollover of an external force acting on the center of gravity position. It is a figure explaining the influence on sex.
[0014]
FIG. 1 shows the type of rollover of a vehicle classified by cause. The types of rollover of a vehicle are classified into “simple rotation”, “simple rotation + skid speed” and “divergence” according to the vehicle behavior in the process of rollover. ”,“ Climbover ”and“ Fallover ”. A typical roll of the “simple rotation + slip speed” type is called “trip over”, and a typical roll of the “divergence” type is called “turn over”.
[0015]
“Flipover” is a rollover that occurs when one of the left and right wheels of a vehicle rides on an obstacle. “Climb over” is a rollover that occurs when a vehicle that has climbed on an obstacle at the bottom and the tire has lifted from the road surface 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 caused by a roll moment with the curb as a fulcrum when the vehicle slips and one of the left and right tires collides with the curb. “Turnover” means that when the steering wheel is operated left and right alternately to perform a double lane change, a triple lane change, or to pass through an S-shaped road, When the natural vibration frequency is approached, the roll angle of the vehicle rolls off due to resonance.
[0016]
FIG. 2 shows a part of the two-dimensional map (first quadrant) for determining the possibility of rollover of the vehicle. The vertical axis roll angle θ corresponds to the right roll angle with a positive value (above the origin). A 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. The opposite side of the line S, that is, the region where the roll angle θ and the roll angular velocity ω are large is defined as a rollover region. Then, when the history lines H1 to H3 of the actual roll angle θ and the roll angular velocity ω of the vehicle cross the threshold value line S from the non-rollover area on the origin side to the rollover area on the opposite origin side, it is determined that the vehicle may roll over. Is done.
[0017]
The history line H1 is a case where only the roll angle θ is slowly increased from the state where the roll angle θ and the roll angular velocity ω are both 0 (origin) and the roll angular velocity ω is substantially held at 0, and the threshold line S When the roll angle θ reaches the critical roll angle θCRT at the point a which is an intercept that intersects the vertical axis, it is determined that the vehicle may roll over. At this time, the center of gravity position 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 becomes a static stability limit for the 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 °.
[0018]
Even if the roll angle θ is 0, the vehicle may roll over if a large roll angular velocity ω is applied. The roll angular velocity ω at this time is defined as a critical roll angular velocity ωCRT.
[0019]
If the vehicle has a roll angular velocity ω in the same direction as the roll angle θ, the roll angular velocity ω facilitates the rollover, and therefore rollover occurs even when the roll angle θ is smaller than the critical roll angle θCRT. Will do. 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 the point b where the history line H2 crosses the threshold value line S from the origin side to the non-origin side. . At this time, the roll angle θ is smaller than the critical roll angle θCRT.
[0020]
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, the hysteresis line H3 becomes the threshold value to shift to a negative value. It is determined that the vehicle does not cross the line S and therefore there is no possibility of the vehicle rolling over.
[0021]
FIG. 3 shows the entire two-dimensional map for determining the possibility of rollover of the vehicle. The two threshold value lines S and S are set in the first quadrant and the third quadrant, and these threshold value lines S and S are point-symmetric about the origin in the initial setting state. No rollover region is set in the second quadrant where the roll angle θ is positive and the roll angular velocity ω is negative, and in 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 in a state where the roll angular velocity ω in the direction opposite to the direction is generated.
[0022]
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 in FIG.
[0023]
The history line H4 corresponds to a “simple rotation” type rollover such as “flipover”, “crimeover”, “fallover”, etc., and the absolute value of the roll angle θ and the absolute value of the roll angular velocity ω are simply Increased and overturned.
[0024]
The history line H5 corresponds to a “simple rotation + slip speed” type rollover called “trip over”, and the roll angular velocity ω is caused by the roll moment generated by the tire colliding with the curb or the like in the process of the vehicle slipping. It has increased rapidly and has turned over.
[0025]
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 the vehicle rolled to the right in the first lane change rolls to the left in the next lane change. It has come to roll over the threshold value line S. The history line H7 indicates a rollover at a triple lane change. A vehicle that rolls to the right at the first lane change rolls to the left at the next lane change and then rolls to the right at the next lane change. absolute value diverges, has come to roll over the first quadrant of the threshold line S of.
[0026]
History line H8, since the roll angle θ is converged toward the origin before exceeding the threshold value line S, does not lead to vehicle rollover in this case.
[0027]
FIG. 4 shows an example of a control system for deploying an air curtain that protects a passenger's head when the vehicle rolls over along the inner side surface of the passenger compartment.
[0028]
An inflator 13 that generates high-pressure gas for deploying the air curtain and an ignition transistor 14 are connected in series between the battery 11 and the grounding unit 12. When the ignition transistor 14 is turned on in response to a command from the electronic control unit U, the inflator 13 is ignited to generate high-pressure gas, and the air curtain that is supplied with the high-pressure gas is developed along the inner side surface of the passenger compartment. In order to determine whether or not the vehicle can roll over, the electronic control unit U includes a signal from the lateral acceleration sensor 15 that detects the lateral acceleration Gy that is the acceleration in the lateral direction of the vehicle body, and a roll that detects the roll angular velocity ω of the vehicle. A signal from the angular velocity sensor 16 and a signal from the vertical acceleration sensor 17 that detects the vertical acceleration Gz that is an acceleration in the vertical direction of the vehicle body are input.
[0029]
As shown in FIGS. 4 and 5, the lateral acceleration sensor 15 fixed to the vehicle body outputs the lateral acceleration Gy when the ignition switch is turned on. Since the vehicle is in a stopped state when the ignition switch is turned on, the lateral acceleration caused by the centrifugal force accompanying the turning of the vehicle is not detected, and only the lateral component of the vehicle body of gravity acceleration G = 1 is set as the lateral acceleration Gy. To detect. Therefore, the initial value θi of the roll angle θ of the vehicle can be calculated by θi = sin ⁻¹ Gy using the lateral acceleration Gy.
[0030]
When the initial value θi of the vehicle roll angle θ is calculated based on the output of the lateral acceleration sensor 15 when the ignition switch is turned on as described above, the variation of the roll angle θ is added to the initial value θi. Thus, the roll angle θ of the vehicle is calculated. That is, the roll angle θ of the vehicle is calculated by adding the integral value ∫ωdt of the roll angular velocity ω output from the roll angular velocity sensor 16 to the initial value θi as the fluctuation amount of the roll angle θ from the time when the ignition switch is turned on. Is done.
[0031]
The lateral acceleration sensor 15 cannot detect the lateral acceleration Gy at the time of free fall of the vehicle, and distinguishes the lateral acceleration caused by the centrifugal force accompanying the turning of the vehicle from the lateral acceleration Gy that is a lateral component of the gravitational acceleration G. Although it has a demerit that it cannot be detected erroneously, the lateral acceleration Gy output by the lateral acceleration sensor 15 is used only for calculating the initial value θi of the roll angle θ of the vehicle when the ignition switch is turned on. The roll angle θ of the vehicle thereafter can be calculated by using the integral value ∫ωdt of the roll angular velocity ω output by the roll angular velocity sensor 16 to eliminate the above disadvantages and calculating the accurate roll angle θ.
[0032]
Thus, a history line that 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 drawn on the map shown in FIG. When the history line crosses the threshold value lines S, S from the origin side to the non-origin side, it is determined that the vehicle may roll over, and the ignition transistor 14 is turned on to ignite the air curtain inflator 13.
[0033]
The above operation will be further described with reference to FIGS.
[0034]
First, in step S1, the lateral acceleration Gy and the roll angular velocity ω are read, and in step S2, threshold value lines S and S on the map are determined according to the lateral acceleration Gy. The threshold lines S and 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, the critical roll angle θCRT and the critical roll angular velocity ωCRT both decrease and the threshold value lines S and S move in the direction approaching the origin, and the lateral acceleration Gy When the rollover of the vehicle is suppressed, the critical roll angle θCRT and the critical roll angular velocity ωCRT both increase and the threshold value lines S and S move in the direction away from the origin. Thereby, the appropriate rollover area and non-rollover area according to the lateral acceleration Gy of the vehicle can be set.
[0035]
When the threshold value line S of the first quadrant moves away from the origin, the threshold value line S of the third quadrant moves toward the origin, and the threshold value line S of the first quadrant approaches the origin. When moving, the threshold line S in the third quadrant moves in a direction away from the origin.
[0036]
When the critical roll angle θCRT and the critical roll angular velocity ωCRT are determined, the equation of the threshold lines S and S is
θ = − (θCRT / ωCRT) ω ± θCRT
(See FIG. 3).
[0037]
Subsequently, it is determined whether the coordinate point P formed by the current roll angle θ1 and the roll angular velocity ω1 is in the rollover region or the non-rollover region. That is, in step S3, the determination value θ2 is calculated by substituting the current value of the roll angular velocity ω1 into ω of the threshold value line S equation. The determination value θ2 is the θ coordinate of the intersection point Q between the straight line ω = ω1 and the threshold value line S. In subsequent step S4, the determination 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 S5. If | θ2 | <| θ1 | is not satisfied, it is determined in step S6 that the coordinate point P formed by the current roll angle θ1 and the roll angular velocity ω1 is in the non-rollover region. FIG. 6 shows the case where the coordinate point P is in the rollover region (| θ2 | <| θ1 |).
[0038]
By the way, as shown in FIG. 8A, if the vehicle is turning left with the roll angle = 0, the center of gravity CG of the vehicle has gravity Fv in the vertical direction and centrifugal force Fh in the horizontal direction to the right. Act. Since the vertical direction of the vehicle coincides with the vertical direction when the vehicle has a roll angle = 0, the vertical force Fz (= m × Gz) obtained by multiplying the vertical acceleration Gz detected by the vertical acceleration sensor 17 by the vehicle body mass m is Since the horizontal direction of the vehicle coincides with the gravity Fv and the horizontal direction of the vehicle coincides with the horizontal direction, the lateral force Fy (= m × Gy) obtained by multiplying the lateral acceleration Gy detected by the lateral acceleration sensor 15 with the vehicle body mass m is the centrifugal force. Matches Fh. In FIG. 8A, the resultant force F of the gravity Fv and the centrifugal force Fh passes through the ground contact point P of the right wheel that is the turning outer wheel, but when the resultant force F passes inside the ground contact point P, The rollover of the vehicle is suppressed by the counterclockwise roll moment, and conversely, when the resultant force F passes outside the contact point P, the rollover of the vehicle is promoted by the clockwise roll moment around the contact point P.
[0039]
However, since the roll angle θ is actually generated when the vehicle turns , as shown in FIG. 8B, the direction of gravity Fv acting on the center of gravity position CG of the vehicle and the direction of centrifugal force Fh are determined by the vertical acceleration sensor. The direction of the vertical force Fz detected at 17 and the direction of the lateral force Fy detected by the lateral acceleration sensor 15 are respectively 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.
[0040]
Fz = Fv cosθ−Fh sinθ
Fy = Fh cosθ + Fv sinθ
As shown in FIG. 8B, 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 a resultant force F of gravity Fv and centrifugal force Fh. Matches. Therefore, even when 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, it is determined by the gravity Fv. Therefore, if the resultant force F passes inside the ground contact point P of the turning outer wheel, the rollover of the vehicle is suppressed, and conversely, if the resultant force F passes outside the ground contact point P, the vehicle Will be promoted.
[0041]
And Thus, when the vehicle rollover by the resultant force F of gravity Fv and centrifugal force Fh acting on the center-of-gravity position CG of the vehicle is suppressed, as shown in FIG. 6, away the threshold line S maps from the origin When the vehicle rollover is accelerated by the resultant force F of the gravity Fv and the centrifugal force Fh acting on the center of gravity position CG of the vehicle, the map is moved in the direction (arrow B direction). Is determined in consideration of the roll moment generated based on the resultant force F by moving the threshold value line S in the direction approaching the origin (in the direction of arrow A) to speed up the determination of the possibility of rollover. Accuracy can be increased.
[0042]
As described above, in this embodiment, the threshold value lines S and S of the map are moved by the lateral acceleration Gy of the vehicle, and the threshold value line of the map is based on the gravity Fv and the centrifugal force Fh acting on the center of gravity position CG of the vehicle. Since S and S are moved, it is possible to accurately determine the possibility of rollover of the vehicle and to deploy the air curtain at an appropriate timing.
[0043]
Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.
[0044]
For example, in the embodiment, the determination of the possibility of rollover of the vehicle is applied to the deployment control of the air curtain, but it is applied to other uses such as the deployment control of the side airbag and the deployment control of the retractable roll bar. can do. In addition, the initial value θi of the roll angle θ of the vehicle can be calculated by θi = cos ⁻¹ Gz using the vertical acceleration Gz that is a vertical acceleration component of the gravitational acceleration G.
[0045]
【The invention's effect】
According to the invention described in claim 1 as described above, based on the external force acting on the center-of-gravity position of the vehicle, since to move the threshold line in a direction away from the direction or the origin of approaching the origin, the external force It is possible to increase the accuracy of determining the possibility of rollover in consideration of the roll moment generated based on the roll moment.
[0046]
According to the second aspect of the present invention, it is possible to further improve the rollover possibility determination accuracy in consideration of the influence of the roll moment generated by the resultant force of gravity and centrifugal force acting on the position of the center of gravity of the vehicle.
[0047]
According to the invention described in claim 3, when the external force acting on the center of gravity position of the vehicle promotes the rollover of the vehicle, the threshold line moves to the origin side, and the external force suppresses the rollover of the vehicle. In this case, the threshold value line moves to the non-origin side, so that it is possible to further increase the determination accuracy of the vehicle rollover possibility.
[Brief description of the drawings]
FIG. 1 is a diagram showing the types of rollover of a vehicle. FIG. 2 is a diagram illustrating the relationship between a roll angle θ and a roll angular velocity ω and the possibility of rollover of the vehicle. Map for Air Curtain [FIG. 4] Block diagram of air curtain control system [FIG. 5] Explanatory diagram of method for calculating initial value θi of roll angle θ from lateral acceleration Gy [FIG. 6] Whether history line is in rollover region or not FIG. 7 is a flowchart showing a method for determining whether the rollover region is present. FIG. 7 is a flowchart for explaining the operation. FIG. 8 is a diagram for explaining the influence of an external force acting on the position of the center of gravity on the rollover possibility.
CG center of gravity position F resultant force (external force)
Fh Centrifugal force Fv Gravity S Threshold line θ Roll angle ω Roll angular velocity

Claims (3)

A threshold value line (S) is set on a two-dimensional map using the vehicle roll angle (θ) and roll angular velocity (ω) as parameters, and the actual roll angle (θ) and roll angular velocity (ω) history lines of the vehicle are set. in there rollover judgment method for a vehicle determines that a possibility exists that the vehicle rolls over when across the threshold line (S) from the non-rollover region of origin side of it to the rollover area of the opposite home side,
A vehicle rollover determination method , wherein the threshold value line (S) is moved in a direction approaching or away from an origin based on an external force (F) acting on a center of gravity (CG) of the vehicle.   2. The vehicle rollover judging method according to claim 1, wherein the external force (F) is a resultant force of gravity (Fv) and centrifugal force (Fh) acting on the center of gravity (CG) of the vehicle.   When the external force (F) acts in a direction that promotes vehicle rollover, the threshold line (S) is moved to the origin side, and the external force (F) acts in a direction that suppresses vehicle rollover. The vehicle rollover judging method according to claim 1, characterized in that said threshold value line (S) is moved to the opposite origin side.

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