JP2001260700A - Rolling over determining method for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy in determining the possibility of the rolling over by detecting the floating-up of one of left and right driving wheels of a vehicle from a road surface in determining the presence of the possibility of the rolling over of the vehicle on the basis of a rolling angle and a rolling angular speed of the vehicle. SOLUTION: A threshold value line S is determined on a two-dimensional map applying the rolling angle θ and a rolling angular speed ω of the vehicle as parameters, and the presence of the possibility of the rolling of the vehicle is determined when a hysteretic line of the actual rolling angle θ and the rolling angular speed ω crosses the threshold value line S from a non-rolling region at an origin side to a rolling region at a non-origin side. When it is detected that one of left and right driving wheels is floated up from the road surface and idled at a high speed by the action of a differential gear, the threshold value line S is close to the origin side from a solid line position to a broken line position to allow the hysteretic line to easily cross a new threshold value line S', whereby the presence of the possibility of the rolling over can be judged earlier, and the performance of the air curtain can be effectively exercised.

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, even if the roll angle θ of the vehicle is the same, when the roll angle θ is generated because the road surface is inclined left and right, one of the left and right wheels of the vehicle is The rollover possibility is different between the case where the roll angle θ is generated due to the rollover and the rollover possibility. That is, at the moment when one of the left and right wheels of the vehicle rises off the road, the vehicle has a roll angular velocity ω in the rollover direction,
As compared with the case where only the roll angle θ is generated and the roll angular velocity ω is not generated on an inclined road surface, the possibility of the vehicle rolling over is increased. Therefore, if it is possible to detect that one of the left and right wheels of the vehicle has lifted off the road surface, it is possible to further improve the accuracy of determining the possibility of rollover.

The present invention has been made in view of the above circumstances, and when determining whether there is a possibility that the vehicle rolls over based on the roll angle and the roll angular velocity of the vehicle, one of the left and right drive wheels of the vehicle is used. An object of the present invention is to increase the accuracy of determining the possibility of rollover by detecting that the vehicle has risen from the road surface.

[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. Wherein the threshold value line is moved to the origin side when the difference between the rotational speed change rates of the left and right driving wheels driven via the differential gears is equal to or greater than a predetermined value. A vehicle rollover determination method is proposed.

According to the above configuration, when the difference between the rotational speed change rates of the left and right drive wheels driven via the differential gears is equal to or greater than a predetermined value, one of the left and right drive wheels is lifted off the road surface and idles. At this time, the threshold value line is moved to the origin side so that the history line can easily cross the threshold value line, so that the rollover possibility determination accuracy can be improved.

[0007]

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 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 diagram 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. FIG. 9 is a diagram illustrating a change in the drive wheel speed, and FIG. 9 is a diagram illustrating a change in the deployment timing of the air curtain due to the lifting phenomenon of the wheels.

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".

[0010] "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 history line H1 shows the case where the roll angle θ and the roll angular velocity ω are both 0 (origin) and the roll angle θ is slowly increased while the roll angular velocity ω is kept substantially zero. 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 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 roll angular velocity ω quickly changes from increasing to decreasing and further shifts to a negative value, so that the history line H3 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 "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 "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 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. Drive wheel speed sensors 17L, 1 for detecting the signal from the angular speed sensor 16 and the left and right drive wheel rotation speeds VL, VR
The signal from 7R is input. As shown in FIG. 5, the left and right drive wheels WL, WR are driven via a differential gear DG.

As shown in FIGS. 4 and 5, the lateral acceleration sensor 15 fixed to the vehicle body has an ignition switch
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 determines 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.

By the way, it is assumed that, for example, the vehicle rolls rightward and the right driving wheel WR of the left and right driving wheels WL, WR driven via the differential gear DG rises from the road surface. In this case, due to the function of the differential gear DG, the left drive wheel WL, which is in contact with the road surface and receives a load, rotates at a rotation speed VL according to the vehicle speed, whereas the right drive wheel floats off the road surface and is in a no-load state. The WR idles and the rotational speed VR increases rapidly. As a result, the left driving wheel W detected by the left driving wheel speed sensor 17L
Rotational speed change rate ΔVL, which is a time derivative of the rotational speed VL of L
Hardly changes, whereas the right driving wheel speed sensor 17R
The rotation speed change rate ΔVR, which is a time differential value of the rotation speed VR of the right drive wheel WR detected by the above, rapidly increases. Therefore, the difference between the rotational speed change rates ΔVL, ΔVR of the left and right drive wheels WL, WR is calculated, and when the absolute value of the difference exceeds a predetermined value ΔV, it is determined that one of the left and right drive wheels WL, WR has risen. be able to. FIG. 8 shows a state in which the right drive wheel WR rises at time t1, the rotation speed VR sharply increases, and a large rotation speed change rate ΔVR is detected.

When it is detected that one of the left and right drive wheels WL, WR has risen from the road surface, a threshold value line for dividing a rollover region and a non-rollover region of a two-dimensional map for determining the possibility of rollover of the vehicle. S, S are moved to the side approaching the origin.

When one of the left and right drive wheels WL, WR slips on a road surface having a small friction coefficient at the time of sudden start or rapid acceleration, or at the time of sudden braking, one of the left and right drive wheels WL, WR has a small friction coefficient. Even when the vehicle is locked by stepping on the road surface, a difference occurs between the rotational speed change rates ΔVL and ΔVR of the left and right drive wheels WL and WR. However, the difference that occurs in this case is smaller than the difference that occurs when one of the left and right drive wheels WL and WR floats and idles, so that the predetermined value Δ
By setting V appropriately, one of the left and right driving wheels WL,
The floating phenomenon of the WR can be reliably detected.

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. In this process, when one of the left and right drive wheels WL, WR rises from the road surface, 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 roll over. It is possible to make a determination as to whether or not there is sex.

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

First, in step S1, the lateral acceleration Gy, the roll angular velocity ωV, and the left and right driving wheel rotational speeds VL, VR are read. 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 the critical roll angle θC, which is the intercept of the vertical axis of the map.
When RT and the critical roll angular velocity ωCRT, which is the intercept of the horizontal axis, are determined, they are determined. In this embodiment, when the rollover of the vehicle is promoted by the lateral acceleration Gy, the critical roll angle θCR
When the threshold value T and the critical roll angular velocity ωCRT both decrease and the threshold value lines S, S move in the direction approaching the origin, and the rollover of the vehicle is suppressed by the lateral acceleration Gy, both the critical roll angle θCRT and the critical roll angular velocity ωCRT The threshold value lines S, S increase and 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 left and right driving wheels WL, which are obtained by time-differentiating the left and right driving wheel rotation speeds VL, VR, respectively.
WR rotation speed change rate ΔVL, absolute value of difference between ΔVR | ΔV
L−ΔVR | is calculated, and if the absolute value | ΔVL−ΔVR | of the difference is equal to or greater than a predetermined value ΔV in step S4, the threshold value line S that separates the rollover region and the non-rollover region is determined in step S5. , S by a predetermined amount to the side approaching the origin. Thereby, the positions of the threshold value lines S, S that partition the rollover region and the non-rollover region are finally determined.

Subsequently, it is determined whether the coordinate point P defined by the current roll angle θ1 and the roll angular velocity ω1 is in the rollover area or the non-rollover area. That is, in step S6, 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 S7, 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 S8. Is determined to be in the rollover region, and if | θ2 | <| θ1 | does not hold, it is determined in step S9 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
|) Are indicated.

FIG. 9 shows the change in the deployment timing of the air curtain according to the lift of one of the left and right drive wheels WL and WR. When the lift phenomenon is not detected, the threshold value line S shown by a solid line is set, and In the history line, the air curtain unfolds across the threshold value line S at R1. On the other hand, when the uplift phenomenon is detected, a threshold value line S 'close to the origin indicated by a broken line is set, and the history line of the vehicle crosses the threshold value line S' at R2, and the air curtain is deployed. In this way, if one of the left and right drive wheels WL, WR comes up early in the process of the vehicle reaching the rollover, the threshold value line S moves to the origin side early accordingly, so that the determination of the possibility of the rollover is made earlier. 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.

[0040]

As described above, according to the first aspect of the present invention, if the difference between the rotational speed change rates of the left and right driving wheels driven via the differential gears is equal to or greater than a predetermined value, one of the left and right driving wheels is switched. It is determined that the drive wheel of the vehicle is floating from the road surface and is spinning, so at this time, the threshold value line is moved to the origin side so that the history line can easily cross the threshold value line, so that the determination accuracy of rollover possibility is improved. Can be enhanced.

[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 diagram showing a change in drive wheel speed due to a wheel lifting phenomenon;

FIG. 9 is a view for explaining a change in the deployment timing of the air curtain due to the lifting phenomenon of the wheel.

[Explanation of symbols]

 DG Differential gear S Threshold value line WL Left drive wheel WR Right drive wheel θ Roll angle ω Roll angular velocity ΔV Predetermined value ΔVL Left drive wheel speed change rate ΔVR Right drive wheel speed change rate

──────────────────────────────────────────────────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 FA15 FA21 3D054 AA06 AA07 AA16 DD28 EE09 EE14 EE18 EE20 EE30 FF20

Claims (1)

[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. Rotational speed change rates (ΔVL, ΔVL) of left and right drive wheels (WL, WR) driven via differential gears (DG)
A method for determining a rollover of a vehicle, wherein the threshold value line (S) is moved to the origin side when the difference of (VR) becomes equal to or more than a predetermined value (ΔV).