JP2004262316A - Vehicle turnover detection device and vehicle occupant protective system using the detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle turnover detection device capable of extremely efficiently and accurately realizing the determination of the turnover of a vehicle by properly setting a threshold for determining the turnover of the vehicle without performing the calibrations of roll-over test and test data for each vehicle model and a vehicle occupant protective system. <P>SOLUTION: Vehicle structure parameters as values different from for each vehicle are stored in an EEPROM3. In the vehicle turnover determination part 4, basic thresholds for determining the turnover of the vehicle are set by using vehicle structure parameters stored in the EEPROM3. When a kinetic energy following the present rotation of the vehicle calculated based on signals from a roll angle velocity sensor 1 and the potential energy of a gravity center moved by the rotation exceed the basis threshold or a threshold obtained by correcting the basic threshold, the determination part determines that the vehicle is in the state of being turned over. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle rollover detection device that detects rollover of a vehicle and a vehicle occupant protection system using the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, various vehicle occupant protection systems have been proposed in which an occupant protection device such as a curtain airbag, a seat belt pretensioner, or an active roll bar is operated when a vehicle rolls over to protect the occupant from an impact caused by the vehicle rolling over. . In such a vehicle occupant protection system, it is required to properly operate the occupant protection device when it is determined that the vehicle rolls over without fail, and it is required to perform the rollover determination of the vehicle with extremely high accuracy. .
[0003]
In the conventional occupant protection system, such a rollover determination of the vehicle is made based on the relationship between the angular velocity (roll angular velocity) of rotation (roll) about the longitudinal axis of the vehicle and the inclination angle (roll angle) of the vehicle due to this rotation. It is generally performed based on (for example, refer to Patent Document 1). When judging the rollover of the vehicle from the relationship between the roll angular velocity and the roll angle, since the roll angular velocity and the roll angle at which the rollover is determined are different for each vehicle type, the actual vehicle is usually used. A rollover test is performed, and calibration for separating a rollover test, a non-rollover test, and a rough road test is performed based on the test data. A threshold value for determining the rollover of the vehicle is set by this calibration. When the roll angular velocity and the roll angle of the vehicle detected during driving of the vehicle exceed the set threshold values, the vehicle rolls over. Is determined.
[0004]
[Patent Document 1]
JP-A-7-164985
[Problems to be solved by the invention]
However, in the conventional techniques as described above, in order to set a threshold value for determining the rollover of the vehicle, it is necessary to repeatedly perform a rollover test for each vehicle type and perform calibration based on the obtained test data waveform, Since the labor and cost required to realize the rollover judgment of the vehicle are enormous, improvement thereof is desired.
[0006]
The present invention has been made in view of the above-described conventional circumstances, and does not perform a rollover test, calibration of test data, and the like for each vehicle type, and appropriately sets a threshold value for determining a rollover of the vehicle. It is an object of the present invention to provide a vehicle rollover detection device and a vehicle occupant protection system capable of extremely efficiently and highly accurately determining a rollover of a vehicle.
[0007]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, depending on the running mode of the vehicle, the rollover model may be considered to be substantially equivalent to the rollover model when the vehicle is stationary. In a simple rollover model, it has been found that the rollover of the vehicle can be properly determined from the state of the potential energy and the kinetic energy of the rolled vehicle using vehicle structural parameters such as the height of the center of gravity of the vehicle, the tread width, and the moment of inertia. . When such a rollover determination is performed, the vehicle structure parameters necessary for the rollover determination are rewritten for each vehicle type, so that an appropriate rollover determination can be made for all types of vehicles.
[0008]
The present invention has been made based on the above knowledge, and a vehicle rollover detecting device according to claim 1 stores a roll angular velocity detecting means for detecting a roll angular velocity of a vehicle, and a structural parameter of the vehicle. And calculating the potential energy and the kinetic energy of the vehicle at the time of rolling based on the roll angular velocity detected by the roll angular velocity detecting means. The calculated potential energy and kinetic energy are stored in the storage means. A vehicle rollover judging means for judging that the vehicle rolls over when a threshold value set using the stored vehicle structure parameters is exceeded.
[0009]
Further, the vehicle rollover detection device according to claim 2 is the vehicle rollover detection device according to claim 1, further comprising an acceleration detection unit that detects a lateral acceleration applied to the vehicle, wherein the vehicle rollover determination unit includes: The threshold value is corrected in accordance with the state of the lateral acceleration applied to the vehicle detected by the acceleration detection means.
[0010]
Further, in the vehicle rollover detection device according to claim 3, in the vehicle rollover detection device according to claim 1, a correction coefficient corresponding to a state of a lateral acceleration applied to the vehicle is stored in the storage unit. The vehicle rollover judging means performs a correction to the threshold value using a correction coefficient stored in the storage means.
[0011]
A vehicle occupant protection system according to a fourth aspect operates the occupant protection device when the vehicle rollover detection device according to any one of the first to third aspects determines that the vehicle rolls over. Is what you do.
[0012]
【The invention's effect】
According to the present invention, the rollover of the vehicle can be properly determined from the state of the potential energy and the kinetic energy of the rolling vehicle using the vehicle structure parameters stored in the storage means. By simply rewriting, it is possible to easily cope with all types of vehicles. Therefore, it is not necessary to perform a rollover test using an actual vehicle or calibrate test data for each vehicle type, and it is possible to extremely efficiently implement a highly accurate vehicle rollover determination.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0014]
FIG. 1 shows the overall configuration of a vehicle occupant protection system to which the present invention is applied. This vehicle occupant protection system determines whether the vehicle rolls over (rolls over), and when it determines that the vehicle rolls over, activates occupant protection devices such as a curtain airbag, a seat belt pretensioner, and an active roll bar. It is intended to protect the occupant when the vehicle rolls over, and includes a roll angular velocity sensor 1, a lateral G sensor 2, an EEPROM 3, a vehicle rollover judging unit 4, an inclination sensor 5, an occupant protection device operating unit 6, and the like.
[0015]
The roll angular velocity sensor 1 detects an angular velocity (roll angular velocity) of rotation (roll) about the front-rear axis of the vehicle. The output signal from the roll angular velocity sensor 1 is filtered by a high-frequency noise removal filter (LPF: Low Pass Filter) 7, AD-converted by an A / D converter 8, and read into the vehicle rollover judging unit 4.
[0016]
The lateral G sensor 2 detects acceleration in the lateral direction of the vehicle (lateral G). The output signal from the lateral G sensor 2 is filtered by a high-frequency noise removing filter (LPF) 9, AD-converted by an A / D converter 10, and read into the vehicle rollover judging unit 4.
[0017]
The EEPROM 3 stores the structural parameters of the vehicle. In the vehicle occupant protection system to which the present invention is applied, as will be described in detail later, the vehicle rollover judging unit 4 judges the rollover of the vehicle using the vehicle structure parameters stored in the EEPROM 3. .
[0018]
The vehicle rollover judging unit 4 calculates the kinetic energy associated with the current rotation of the vehicle and the potential energy of the center of gravity moved by the rotation based on the signal from the roll angular velocity sensor 1, and calculates the kinetic energy and the potential energy. Is determined to exceed the predetermined threshold, it is determined that the vehicle rolls over.
[0019]
Here, a specific method of the rollover determination in the vehicle rollover determination unit 4 will be described. The rollover of the vehicle when two wheels on one side of the vehicle are fixed shafts (the coefficient of friction between the wheels and the road surface is infinite) is considered based on the vehicle rollover model in FIG. In FIG. 2, OG is the position of the center of gravity of the vehicle, H is the height of the center of gravity of the vehicle, L is the distance from the wheel contact surface to the position of the center of gravity, W is the tread width, M is the vehicle weight, and g is the gravitational acceleration (9.8 m / sec). ² ) are shown.
[0020]
From the rollover model shown in FIG. 2, the potential energy X of the current center of gravity that moves with the rotation (roll) of the vehicle is obtained by the following equation (1). Here, Φ is a vehicle roll angle obtained by an integral value (∫Φdt) of an angular velocity signal (deg / sec) obtained from the roll angular velocity sensor 1, and ΦO is obtained by subtracting SSA (Static Stability Angle) from 90 degrees. The angle is (90-arctan ((W / 2) / H)). The SSA indicates the roll angle Φ when the position of the center of gravity (OG) of the vehicle becomes the highest, and is represented by arctan ((W / 2) / H).
[0021]
X = Mg (Lsin [ΦO + Φ] -H) (1)
Further, from the rollover model shown in FIG. 2, the kinetic energy Y associated with the rotation (roll) of the vehicle is obtained by the following equation (2). Here, IO is a moment of inertia around the center of gravity (OG), and ω is a value obtained by replacing the angular velocity signal (deg / sec) obtained from the roll angular velocity sensor 1 in rad / sec units.
[0022]
Y = 1/2 (IO + ML ² ) ω ² (2)
Among the parameters required for the calculations by the above equations (1) and (2), the moment of inertia around the center of gravity, the vehicle weight M, the distance L from the wheel contact surface to the center of gravity, the tread width W, the height of the center of gravity of the vehicle H is a vehicle structure parameter derived from the structure of the vehicle, and is a value predetermined for each vehicle, in other words, a value that differs for each vehicle. In the vehicle occupant protection system to which the present invention is applied, these vehicle structure parameters are stored in the EEPROM 3. Using these vehicle structural parameters, the vehicle rollover judging unit 4 uses the kinetic energy associated with the current rotation of the vehicle and the potential energy of the center of gravity moved by the rotation as the energy required for the vehicle to roll over. By judging whether or not the vehicle is rolling over, it is detected whether or not the vehicle is in a rollover state.
[0023]
The energy required for the vehicle to roll over is determined by the following equation (3).
[0024]
1/2 (IO + ML ² ) ω ² + Mg (Lsin [ΦO + Φ] −H) = Mg (L−H) (3)
In the above equation (3), （(IO + ML ² ) ω ² is the kinetic energy Y associated with the rotation of the vehicle, and Mg (Lsin [ΦO + Φ] -H) is the potential energy of the center of gravity moving with the rotation of the vehicle. X. Therefore, when the above equation (3) is plotted on a graph with the potential energy (Nm ^1/2 ) on the X axis and the kinetic energy (Nm ^1/2 ) on the Y axis, as shown in FIG. 3, Y = −X + Mg It is represented by the line (LH). Then, this line is used as a basic threshold value for rollover determination, and in a situation where the friction coefficient between the wheel and the road surface is considered to be infinite, basically, the vehicle moves by kinetic energy and rotation accompanying the rotation of the vehicle. When the potential energy of the center of gravity exceeds the basic threshold value, it can be determined that the vehicle rolls over. Note that Mg (LH) is a fixed value determined by the vehicle structure parameter, and by reading out the vehicle structure parameter stored in the EEPROM 3, the basic threshold value for judging rollover in the vehicle is determined.
[0025]
In the above, the case where two wheels on one side of the vehicle are fixed shafts (the coefficient of friction between the wheels and the road surface is infinite) was considered. However, as shown in FIG. Is the same when the value is zero.
[0026]
In this case, the potential energy X of the current center of gravity moving with the rotation (roll) of the vehicle is obtained by the above equation (1), as in the above-described example. The kinetic energy Y associated with the rotation (roll) of the vehicle is obtained by the following equation (4).
[0027]
Y = １ ／ (ML ² cos [ΦO + Φ] ² + IO) ω ² (4)
The energy required for the vehicle to roll over is obtained by the following equation (5).
[0028]
1/2 (ML ² cos [ΦO + Φ] ² + IO) ω ² + Mg (Lsin [ΦO + Φ] −H) = Mg (L−H) (5)
In the above equation (5), （(ML ² cos [ΦO + Φ] ² + IO) ω ² is the kinetic energy Y associated with the rotation of the vehicle, and Mg (Lsin [ΦO + Φ] −H) is associated with the rotation of the vehicle. This is the potential energy X of the moving center of gravity. Therefore, when the above equation (5) is plotted on a graph in which the potential energy (Nm ^1/2 ) is on the X axis and the kinetic energy (Nm ^1/2 ) is on the Y axis, Y = −X + Mg, as in the example described above. It is represented by the line (LH). Then, this line is used as a basic threshold value for rollover judgment, and in a situation where the friction coefficient between the wheel and the road surface is considered to be zero, basically, the kinetic energy accompanying the rotation of the vehicle and the center of gravity moving due to the rotation When the potential energy exceeds the basic threshold value, it can be determined that the vehicle rolls over.
[0029]
As described above, in a situation in which the friction coefficient between the wheel and the road is considered to be infinite or a situation in which the friction coefficient between the wheel and the road is considered to be zero, the data is basically stored in the EEPROM 3. The rollover of the vehicle can be determined using the basic threshold value determined based on the vehicle structure parameters obtained. However, in actuality, the vehicle weight, the height of the center of gravity, and the like may slightly change according to the number of occupants, the state of loading of luggage, and the like. In such a case, the basic threshold value may be set in consideration of worst conditions such as the maximum number of occupants and the maximum load weight, and in consideration of a margin as the energy amount.
[0030]
Further, actually, the friction coefficient varies depending on the state of the road surface on which the vehicle runs, and it is necessary to consider this point. Such a coefficient of friction between the wheel and the road surface depending on the road surface condition can be indirectly determined from the lateral acceleration (lateral G) of the vehicle. Therefore, in the vehicle occupant protection system to which the present invention is applied, in the vehicle rollover judging section 4, an equal energy with respect to the basic threshold value is determined in accordance with the signal from the lateral G sensor 2, that is, the state of occurrence of lateral G applied to the vehicle. Correction is made so as to increase or decrease the target margin, and rollover of the vehicle is determined using the corrected threshold value (the line shown by the broken line in FIG. 3).
[0031]
When correcting the basic threshold value defined by the potential energy and the kinetic energy, the ratio of the energy amounts corrected by the potential energy and the kinetic energy becomes equal. By storing information (correction coefficient) as to whether the margin of the percentage should be increased or decreased, such correction of the basic threshold value can be easily performed. Such information may be stored in advance in an EEPROM 3 or the like together with the above-mentioned vehicle structure parameters by previously obtaining an optimum margin amount according to the occurrence state of the lateral G by an experiment or the like.
[0032]
In a rollover mode of the vehicle, the friction coefficient between the wheel and the road surface may change abruptly, and such a change in the friction coefficient needs to be reflected in the rollover determination of the vehicle. Therefore, in the vehicle occupant protection system to which the present invention is applied, when the vehicle rollover judging unit 4 judges that the deceleration G in the vehicle lateral direction has suddenly changed based on the signal from the lateral G sensor 2, It is determined that the friction coefficient between the wheel and the road surface has changed abruptly, the basic threshold value is corrected according to the degree of the change, and the rollover of the vehicle is determined using the corrected threshold value.
[0033]
Explaining with a specific example, during a so-called turnover type rollover such as when the vehicle rolls over a sharp curve at high speed, the friction coefficient between the wheels and the road surface does not change abruptly. In addition, the friction coefficient between the wheel and the road surface changes suddenly even during a so-called fallover rollover in which one wheel of the vehicle rolls over an obstacle or falls off the side of the road. There is no. On the other hand, as shown in FIG. 5, when the wheels roll over while skidding, that is, when the vehicle rolls over in a so-called trip system, the friction coefficient between the wheels and the road surface increases rapidly, and a large deceleration G occurs accordingly. There is also.
[0034]
FIG. 6A shows how the vehicle lateral deceleration G occurs when the trip system rolls over, and FIG. 6B shows how the roll angle occurs. As shown in FIGS. 6A and 6B, when the trip system rolls over, the roll angle of the vehicle at the point where the large deceleration G occurs is small, but at this point the vehicle rolls over. Just have enough energy. Since the roll angle of the vehicle at the time when the friction coefficient μ between the wheel and the road surface suddenly changes is about several degrees, the vehicle lateral deceleration G at this time is Yhg (vehicle lateral deceleration G). = ΜRz / M ≒ μMg / M = μg (Rz is a perpendicular resistance, Rz = Mgcosθ, but is almost represented by Mg because the roll angle is very small). Therefore, the friction coefficient μ between the wheel and the road surface is represented by μ = Yhg / g.
[0035]
As described above, when the vehicle rollover judging unit 4 judges that the deceleration G in the vehicle lateral direction has changed abruptly based on the signal from the lateral G sensor 2, the friction coefficient between the wheel and the road surface suddenly increases. And the basic threshold value for rollover determination is corrected. Here, the correction of the basic threshold value is performed, for example, as shown in FIGS. 7 (a) and 7 (b), by dividing the level according to the degree of change of the deceleration G, that is, the degree of change of the friction coefficient between the wheel and the road surface. And then do it.
[0036]
In addition, in practice, it is necessary to consider the characteristics of suspensions that differ from vehicle to vehicle, and in this regard, correction is performed on the above-described basic threshold value so as to add an equal energy margin as a suspension correction coefficient. Just do it. The suspension correction coefficient, that is, the equal energy margin amount is, for example, the inertia moment IO around the vehicle center of gravity, the vehicle weight M, the distance L from the wheel contact surface to the center of gravity, the tread width W, the center of gravity H of the vehicle, and the like. These parameters may be stored in the EPROM 3 as vehicle structure parameters.
[0037]
In the vehicle rollover judging unit 4, the kinetic energy associated with the current rotation of the vehicle and the potential energy of the center of gravity moved by the rotation, which is calculated based on the signal from the roll angular velocity sensor 1, are based on the basic threshold described above or this basic threshold. When the corrected threshold value is exceeded, it is determined that the vehicle is in a rollover state, and a Hi-level rollover detection signal is output. The rollover detection signal from the vehicle rollover judging unit 4 is input to the AND circuit 11.
[0038]
Further, in the vehicle occupant protection system to which the present invention is applied, an inclination sensor 5 that is turned on in accordance with the inclination of the vehicle is provided, and an output signal from the inclination sensor 5 is provided after chattering is removed by the LPF 12. , Is output as a vehicle inclination signal from the inclination determination block 13 and is input to the AND circuit 11. When the AND circuit 11 determines that an AND condition between the rollover detection signal from the vehicle rollover determination unit 4 and the vehicle tilt signal from the tilt determination block 13 is satisfied, it is determined that the vehicle rolls over without fail. An occupant protection device such as a curtain airbag, a seat belt pretensioner, an active roll bar, or the like is operated by the protection device operating section 6 to protect the occupant when the vehicle rolls over.
[0039]
As described above, according to the vehicle occupant protection system to which the present invention is applied, the vehicle rollover determination unit 4 can accurately determine the rollover of the vehicle using the vehicle structure parameters stored in the EEPROM 3, By simply rewriting different vehicle structure parameters for each vehicle, it is possible to easily cope with all types of vehicles. Therefore, it is not necessary to repeatedly perform a rollover test using an actual vehicle for each vehicle type and perform calibration based on the obtained test data waveform as in the conventional case, and it is extremely efficient to determine a rollover of a vehicle with high accuracy. It is possible to realize it.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a vehicle occupant protection system to which the present invention is applied.
FIG. 2 is a diagram illustrating a rollover model of a vehicle when two wheels on one side of the vehicle are used as fixed axes.
FIG. 3 is a diagram showing a basic threshold value for vehicle rollover determination on a graph in which potential energy is set on the X axis and kinetic energy is set on the Y axis.
FIG. 4 is a diagram illustrating a rollover mode of a vehicle when a friction coefficient between wheels and a road surface is zero.
FIG. 5 is a view showing a rollover mode of a trip system in which a friction coefficient between a wheel and a road surface rapidly increases.
FIG. 6 is a diagram showing how a vehicle lateral deceleration G and a roll angle occur when the trip system rolls over.
FIG. 7 is a diagram illustrating an example in which correction of a basic threshold is performed by dividing the level according to the degree of change in deceleration G;
[Explanation of symbols]
1 Roll angular velocity sensor 2 Lateral G sensor 3 EEPROM
4 Vehicle rollover judging unit 5 Tilt sensor 6 Occupant protection device operating unit

Claims (4)

A roll angular velocity detecting means (1) for detecting a roll angular velocity of the vehicle;
Storage means (3) for storing structural parameters of the vehicle;
Based on the roll angular velocity detected by the roll angular velocity detecting means (1), potential energy and kinetic energy of the vehicle at the time of rolling are calculated, and the calculated potential energy and kinetic energy are stored in the storage means (3). A vehicle rollover detecting means for determining that the vehicle rolls over when a threshold value set using a vehicle structure parameter stored in the vehicle rollover is used. The vehicle further includes acceleration detection means (2) for detecting a lateral acceleration applied to the vehicle,
The vehicle rollover judging means (4) corrects the threshold value according to a state of a lateral acceleration applied to the vehicle detected by the acceleration detecting means (2). Vehicle rollover detection device. A correction coefficient according to the state of the lateral acceleration applied to the vehicle is stored in the storage means (3),
The vehicle rollover detection device according to claim 2, wherein the vehicle rollover determination unit (4) performs correction on the threshold using a correction coefficient stored in the storage unit (3). A vehicle occupant protection system comprising: activating an occupant protection device when the vehicle is detected to roll over by the vehicle rollover detection device according to any one of claims 1 to 3.

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