JP3567962B2 - Vehicle center-of-gravity height estimation device and rollover prevention device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for estimating the height of the center of gravity of a vehicle and a rollover prevention apparatus capable of determining the height of the center of gravity of a vehicle that varies depending on a load, and for example, accurately determining the risk of rollover when the vehicle turns.
[0002]
[Related background art]
In the case of vehicles such as trucks and buses, it cannot be denied that the height of the center of gravity of the vehicle changes depending on the load and the load such as passengers. In particular, the height of the center of gravity of a truck varies greatly depending on the type of load (difference in weight, bulk, etc.) and the loading condition (height of load, etc.). Such a change in the height of the center of gravity of the vehicle directly causes a change in the roll angle when the vehicle turns. Therefore, in order to prevent the vehicle from rolling over when turning, it is important to control the behavior of the vehicle, for example, the turning speed, after grasping the height of the center of gravity of the vehicle.
[0003]
[Problems to be solved by the invention]
Conventionally, for example, Japanese Patent Application Laid-Open No. Hei 6-297895 discloses a technique of executing deceleration control according to the height of the center of gravity of a vehicle in order to prevent the vehicle from rolling over when turning. However, the technology disclosed in this publication determines the lateral acceleration generated in the vehicle in accordance with a threshold value set based on the height of the center of gravity of the vehicle and the roll angle, and executes the rollover prevention control of the vehicle. Is obtained only in accordance with the position of the center of gravity determined in the above and the respective outputs of the ground displacement meters provided at three points of the vehicle body.
[0004]
That is, on the assumption that the position of the center of gravity determined in the vehicle body coordinate system does not change, it is considered that the position of the center of gravity has been vertically displaced in accordance with the displacement of the vehicle body coordinate system determined from the output of the ground displacement meter. It's just For this reason, even if the height of the center of gravity of the vehicle changes depending on the form of the load on the vehicle, specifically, the load amount or the load form, there is a problem that it cannot be dealt with at all. In particular, when the loading conditions change greatly, such as in a truck, no measure can be taken.
[0005]
The present invention has been made in view of such circumstances, and its purpose is to accurately determine the height of the center of gravity of a vehicle that changes depending on the load, and furthermore, according to the height of the center of gravity, the vehicle rolls over when turning. It is an object of the present invention to provide an apparatus for estimating the height of the center of gravity of a vehicle and a rollover prevention device which can accurately judge the danger of the vehicle and take appropriate measures to prevent the rollover.
[0006]
[Means for Solving the Problems]
In order to achieve the above-described object, a vehicle center-of-gravity height estimating apparatus according to the present invention includes a roll angle of a vehicle, a lateral acceleration acting on the vehicle, and a detecting unit that detects a weight of the vehicle. A center-of-gravity height estimating means for estimating the center of gravity of the vehicle based on the detected roll angle, lateral acceleration, and vehicle weight; and a roll angular velocity detecting means for detecting a roll angular velocity; In the method, when the roll angular velocity is equal to or less than a predetermined value, the roll angle and the lateral acceleration are used for estimating the center of gravity, and when the roll state is substantially steady, the center of gravity is estimated with high accuracy. It is characterized by.
[0007]
Further , as described in claim 2 , the vehicle weight is determined by a braking pressure at the time of vehicle braking detected using braking pressure detecting means and a deceleration of the vehicle detected using deceleration detecting means. A simple vehicle weight is detected by using a vehicle weight estimating means for estimating the vehicle weight based on the vehicle weight.
[0008]
The vehicle rollover prevention device according to the present invention includes the above-described vehicle center-of-gravity height estimating device as described in claims 3 and 4 , and further includes a driving state of the vehicle, for example, when turning. Equipped with means for detecting lateral acceleration of the vehicle, and means for performing safety measures for taking safety measures for preventing rollover,
Further, reference value setting means for setting a reference value that is a threshold value for determining the risk of rollover of the vehicle based on the height of the center of gravity of the vehicle estimated by the center-of-gravity height estimation means, and the detected driving state exceeds the reference value. And a rollover prevention control means for activating the safety measure execution means.
[0009]
That is, the vehicle rollover prevention device according to the present invention sets a reference value that is a criterion for judging the rollover danger of the vehicle in accordance with the center of gravity of the vehicle estimated by the center of gravity height estimating means. When the lateral acceleration (driving state) acting on the vehicle exceeds the reference value, the safety measure executing means is operated to take a safety measure for preventing the vehicle from rolling over. . In particular, the operating conditions of the safety measure execution means are varied according to the height of the center of gravity of the vehicle, which varies depending on the load, so that safety measures for preventing rollover according to the driving state can be performed regardless of the load state of the load. The feature is that it can be taken appropriately.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a vehicle center-of-gravity height estimating apparatus according to an embodiment of the present invention and a vehicle rollover prevention apparatus including the center-of-gravity height estimating apparatus will be described with reference to the drawings.
FIG. 1 is a block diagram showing an overall schematic configuration of a rollover prevention device provided with a center-of-gravity height estimation device. In FIG. 1, reference numeral 1 denotes a center-of-gravity height estimation processing unit (center-of-gravity height estimating means) which is a main component of the center-of-gravity height estimating apparatus, and is realized as a part of the processing function of, for example, arithmetic processing means including a microprocessor. The center-of-gravity height estimation processing unit 1 detects the roll angle Φ of the vehicle detected by the roll angle detection unit 2, the lateral acceleration Gy of the vehicle detected by the lateral acceleration detection unit 3, and the vehicle weight detection unit 4. According to the weight M of the vehicle, as described later, the height H of the center of gravity of the vehicle is estimated based on the equation of motion at the time of turning the vehicle.
[0011]
Here, the roll angle detecting means 2 converts a roll angular velocity φ detected using a roll angular velocity detector 2a such as a roll rate sensor into a high-pass filter (HPF) 2b and a low-pass filter (LPF). After filtering in order through 2c, the roll angular velocity φ is integrated using an integrator 2d, thereby obtaining the roll angle Φ. The lateral acceleration detecting means 3 is configured to filter and output the lateral acceleration Gy in the vehicle width direction detected using the lateral acceleration detector 3a including an acceleration sensor or the like via the LPF 3b.
[0012]
Further, the vehicle weight detecting means 4 applies acceleration (deceleration) Gx in the longitudinal direction of the vehicle detected by using a deceleration detector 4a including an acceleration sensor, and a braking force applied to a braking system to a braking force such as a pressure sensor. After the brake air pressure P detected by the pressure detector 4b is filtered through the LPFs 4c and 4d, respectively, the vehicle weight M is determined according to the acceleration (deceleration) Gx and the brake air pressure P as described later. And a vehicle weight estimation processing unit (weight estimation means) 4e for estimating the vehicle weight. The vehicle weight estimation processing unit 4e is also realized as a part of the processing function of the arithmetic processing unit including a microprocessor, similarly to the center-of-gravity height estimation processing unit 1 described above.
[0013]
On the other hand, the device for preventing rollover of the vehicle includes the center-of-gravity estimating device configured as described above, and the driving state detecting means 5 for detecting the driving state of the vehicle, and the rollover of the driving state detected by the driving state detecting means 5. Judgment means for comparing the danger with a predetermined judgment criterion and activating safety measure execution means 6 such as an automatic deceleration control device for taking safety measures for preventing the vehicle from rolling over according to the judgment result ( Reference value setting means 8 for setting a reference value as a criterion for determining the risk of rollover in accordance with the height H of the center of gravity of the vehicle obtained by the center-of-gravity height estimation processing section 1 It comprises.
[0014]
The driving state detecting means 5 detects, for example, the lateral acceleration Gy in the vehicle width direction detected by using the above-described lateral acceleration detector 3a as a driving state related to a rollover factor acting when the vehicle turns. Thus, the judging means 7 compares the reference value set by the reference value setting means 8 with the operating state (lateral acceleration Gy) to judge whether or not the operating state has a possibility of rollover. . When the lateral acceleration Gy obtained as the driving state exceeds the reference value, the determining means 7 determines that there is a high risk of the vehicle rolling over, and activates the safety measure execution means 6. Under such an operation, the vehicle is decelerated by applying a braking force to the vehicle or the like to avoid an operation state including a risk of deceleration rollover. The safety measure executing means 7 may be not only the above-described automatic braking control by the automatic deceleration control device but also a means for alerting the driver by issuing an alarm.
[0015]
The reference value setting means 8 sets the criterion used for determining the possibility of rollover in accordance with the center-of-gravity height H estimated by the center-of-gravity height estimation processing unit 1 as described above. A limit value of the lateral acceleration Gy that can prevent the vehicle from rolling over is set in advance by referring to table data obtained according to the height H of the center of gravity. More specifically, when the height H of the center of gravity of the vehicle is low, it is difficult to roll over. Therefore, a relatively large lateral acceleration Gy is allowed by setting a high reference value including a limit lateral acceleration for preventing rollover as a criterion. Like that. Conversely, when the height H of the center of gravity is high, the reference value including the limit lateral acceleration for preventing the rollover is set to a low value, whereby the allowable lateral acceleration Gy is greatly limited. That is, the reference value setting means 8 obtains the limit of the lateral acceleration Gy that can reliably prevent the vehicle from rolling over according to the estimated center-of-gravity height H, and uses this as a criterion (reference value) for preventing the vehicle from rolling over.
[0016]
Therefore, the danger of rollover is determined from the driving state (lateral acceleration Gy) of the vehicle under the reference value set according to the height H of the center of gravity of the vehicle, and the safety measure execution means 7 operates according to the determination result. Therefore, even if the height H of the center of gravity of the vehicle changes depending on the state of the vehicle, it is possible to reliably avoid the possibility of rollover during turning according to the driving state at that time.
[0017]
Here, a description will be given of the estimation process of the height H of the center of gravity of the vehicle described above. When the vehicle turns steadily, the force acting on the vehicle is:
(H-Hrc) · M · Gy = G · Φ
It can be expressed by the following equation of motion. Here, H is the height of the center of gravity of the vehicle, Hrc is the height of the roll center when the vehicle turns, M is the weight (mass) of the vehicle, Gy is the lateral acceleration acting on the vehicle, G is the roll rigidity value of the vehicle, and Φ is This is the roll angle of the vehicle. As shown in this equation of motion, the force acting on the vehicle during turning is greatly affected by the height H of the center of gravity and the weight M of the vehicle. Further, the roll center height Hrc and the roll rigidity value G are substantially constant, and can be regarded as almost constant. Therefore, if the height H of the center of gravity of the vehicle and its weight M, which changes depending on the state of the load, are clear, the relationship between the roll angle Φ of the vehicle and the lateral acceleration Gy acting on the vehicle at that time is calculated according to the above equation of motion. The possibility of rollover can be determined.
[0018]
Thus, the center-of-gravity height estimating apparatus easily obtains the roll angle Φ of the vehicle without using an expensive roll angle sensor by integrating the roll angular velocity φ detected by the roll rate sensor as described above. . On the other hand, with respect to the weight M of the vehicle that changes depending on the state of the cargo, the deceleration (acceleration in the front-rear direction) Gx acting on the vehicle and the braking force F at that time are F = M · Gx
And that the braking force F is expressed as a function of the brake coefficient B and the brake air pressure P. Specifically, the brake coefficients Bf and Br of the front and rear wheels and the brake air pressure Pf, By Pr, F = Bf · Pf + Br · Pr (= BP)
As shown.
[0019]
The body weight estimation processing unit 4e in the center-of-gravity height estimating apparatus focuses on such a motion relationship, and calculates the brake air pressure P when braking is applied during steady running and the deceleration applied to the vehicle at that time. From Gx, the weight M of the vehicle is estimated. Then, the center-of-gravity height estimation processing unit 1 calculates the above-described luck (for the center-of-gravity height H) in accordance with the vehicle weight M obtained during the steady running, the roll angle Φ of the vehicle, and the lateral acceleration Gy acting at that time, as described above. Solved estimation formula) The center of gravity H of the vehicle is estimated by an estimation process based on the dynamic equation. Therefore, the height H of the center of gravity of the vehicle, which changes depending on the loaded state, can be accurately obtained regardless of the loaded state of the load.
[0020]
Thus, according to the present apparatus for estimating the height H of the center of gravity, which varies depending on the state of the cargo, as described above, according to the vehicle weight M, the roll angle Φ, and the lateral acceleration Gy obtained during steady running, the safety of the automatic deceleration control device and the like The criterion for operating the measure execution means 6 can be appropriately set in accordance with the height H of the center of gravity estimated as described above. As a result, irrespective of the state of the load, the operation state is determined under a reference value set based on the height of the center of gravity H obtained according to the state of the load, and safety measures for preventing rollover, for example, The automatic deceleration control can be appropriately performed. Therefore, effects such as the drivability being impaired due to excessive action of the safety measures and the inconvenience such as the failure of the safety measures to function properly can be prevented.
[0021]
Further, as described above, since the roll angle Φ is obtained by integrating the output of the roll rate sensor, the roll angle can be detected relatively easily. Further, since the vehicle weight M is estimated from the brake air pressure P and the deceleration Gx acting on the vehicle, the height H of the center of gravity can be relatively easily estimated. , The sensor system can be compelled. Then, the height H of the center of gravity can be easily and effectively obtained, and the reference value for determining the risk of rollover can be obtained in accordance with the height H of the center of gravity. .
[0022]
When estimating the height H of the center of gravity, for example, as shown in FIG. 2, the roll rate (roll angular velocity) φ accompanying the steering operation during steady running is changed to a change in the steering wheel angle θ as shown in FIG. Accordingly, the roll rate φ changes as shown in FIG. 2B, so that the roll rate φ may be integrated as shown in FIG. 2C to obtain the roll angle Φ. Further, since the lateral acceleration Gy generated in the vehicle changes as shown in FIG. 2D according to the change in the roll angle Φ, for example, when the roll rate φ becomes zero (0) and the roll angle Φ becomes constant May be determined. Specifically, in the case where the vehicle turns slowly at the beginning of the traveling start, the roll angle Φ and the lateral acceleration Gy at that time are obtained at the above-mentioned timing to estimate the height H of the center of gravity. Good.
[0023]
By using the roll angle φ and the lateral acceleration Gy when the roll rate φ is zero (0) in this manner, the height H of the center of gravity can be easily estimated during steady turning, and the estimation accuracy can be improved. Can be expected. In this case, the roll rate serving as the threshold is not limited to zero (0) as described above, and may be equal to or lower than a low-level predetermined value. Further, the roll rate sensor can also be used for detecting the roll angle described above, so that an increase in cost can be suppressed.
[0024]
If the height H of the center of gravity is estimated as described above based on the roll angle Φ and the lateral acceleration Gy determined as described above, for example, when the vehicle returns to straight running, the integral value of the roll rate φ (roll angle Φ ) May be reset to prepare for the detection of the roll angle Φ again during the subsequent turning. At this time, while judging the danger of rollover according to the previously obtained center of gravity H, the center of gravity H is sequentially learned according to the center of gravity H obtained again, and the detection accuracy of the center of gravity H may be increased. good.
[0025]
The center of gravity H obtained as described above may be reset by manual operation of the vehicle driver, for example, in accordance with a load transfer operation, or the center of gravity H may be significantly different from the center of gravity H already obtained. It is determined that the status of the cargo has changed at the time when is obtained, and the center of gravity H newly obtained may be updated. In addition, the present invention can be variously modified and implemented without departing from the gist thereof.
[0026]
【The invention's effect】
As described above, according to the first aspect of the present invention, the height of the center of gravity is estimated using the roll angle and the lateral acceleration when the roll state is almost in a steady state, so that the estimation accuracy can be further improved. it can. According to the second aspect of the present invention, since the height of the center of gravity is estimated by calculating the vehicle weight according to the braking pressure and the deceleration, the height of the center of gravity can be obtained relatively easily while detecting the vehicle weight.
[0027]
Further, according to the third and fourth aspects of the present invention, a criterion value for taking safety measures for preventing rollover is determined according to the height of the center of gravity determined as described above, and the driving state of the vehicle is determined according to the criterion. As a result, the above safety measures can be actuated, so that there is a great effect in practical use, for example, measures such as deceleration control can be appropriately taken to prevent rollover regardless of the state of the load. Can be
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an apparatus for estimating the center of gravity of a vehicle according to an embodiment of the present invention, and a rollover prevention apparatus for a vehicle including the apparatus for estimating the center of gravity.
FIG. 2 is a diagram showing the timing of a center-of-gravity height estimation process in one embodiment of the present invention.
[Explanation of symbols]
1 Center of gravity height estimation processing unit (Centroid height estimation means)
2 roll angle detecting means 2a roll angular velocity detector 2d integrator 3 lateral acceleration detecting means 3a lateral acceleration detector 4 vehicle weight detecting means 4a deceleration detector 4b braking pressure detector 4e vehicle weight estimating processing unit (weight estimating means)
5 Operating state detection means 6 Automatic deceleration control device (safety measure execution means)
7 determination means (rollover prevention control means)
8 Reference value setting means

Claims (4)

Roll angle detection means for detecting the roll angle of the vehicle, lateral acceleration detection means for detecting the lateral acceleration acting on the vehicle, vehicle weight detection means for detecting the weight of the vehicle, and the vehicle weight detection means A center-of-gravity height estimating apparatus comprising: a center-of-gravity height estimating unit that estimates a center-of-gravity height of the vehicle based on a roll angle, a lateral acceleration, and a vehicle weight,
The apparatus further comprises a roll angular velocity detecting means for detecting a roll angular velocity, wherein the center of gravity height estimating means estimates the height of the center of gravity using the roll angle and the lateral acceleration when the roll angular velocity is equal to or less than a predetermined value. A device for estimating the center of gravity of a vehicle. Roll angle detection means for detecting the roll angle of the vehicle, lateral acceleration detection means for detecting the lateral acceleration acting on the vehicle, vehicle weight detection means for detecting the weight of the vehicle, and the vehicle weight detection means A center-of-gravity height estimating apparatus comprising: a center-of-gravity height estimating unit that estimates a center-of-gravity height of the vehicle based on a roll angle, a lateral acceleration, and a vehicle weight,
The vehicle weight detecting means detects the vehicle weight based on a braking pressure at the time of vehicle braking detected using braking pressure detecting means and a deceleration acting on the vehicle detected using deceleration detecting means. An apparatus for estimating the height of the center of gravity of a vehicle, comprising: a weight estimating means for estimating the center of gravity of the vehicle. Roll angle detection means for detecting the roll angle of the vehicle, lateral acceleration detection means for detecting the lateral acceleration acting on the vehicle, vehicle weight detection means for detecting the weight of the vehicle, and the vehicle weight detection means A rollover prevention device including a vehicle center-of-gravity height estimating device including: a center-of-gravity height estimating unit that estimates a center of gravity of the vehicle based on a roll angle, a lateral acceleration, and a vehicle weight,
Driving state detecting means for detecting a driving state of the vehicle; safety measure executing means for taking safety measures for preventing the vehicle from rolling over; and a vehicle center of gravity estimated by the center of gravity height estimating means. A reference value setting means for setting a reference value serving as a criterion for determining the risk of rollover of the vehicle, and when the driving state determined by the driving state detection means exceeds a reference value set by the reference value setting means, A rollover prevention device for a vehicle, comprising: a rollover prevention control unit that activates a safety measure execution unit. A rollover prevention device comprising the vehicle center-of-gravity height estimation device according to claim 1 or 2 ,
Driving state detecting means for detecting a driving state of the vehicle; safety measure executing means for taking safety measures for preventing the vehicle from rolling over; and a vehicle center of gravity estimated by the center of gravity height estimating means. A reference value setting means for setting a reference value serving as a criterion for determining the risk of rollover of the vehicle, and when the driving state determined by the driving state detection means exceeds a reference value set by the reference value setting means, A rollover prevention device for a vehicle, comprising: a rollover prevention control unit that activates a safety measure execution unit.

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