JPH11258260A - Estimation device for roll angle of vehicle apparatus for prevention of roll by using the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an estimation device, for the roll angle of a vehicle, by which the roll range of the vehicle can be detected without a need of a special detection means and to provide an apparatus for the prevention of a roll by using the device. SOLUTION: An estimation device 3 for a roll angle estimates the roll angle θof a vehicle by using a transverse acceleration detected by a transverse accelerometer 10, by using vehicle speeds detected by vehicle speed sensors 6 to 9 and by using an estimated acceleration estimated on the basis of a yaw rate detected by a yaw rate sensor 11. Thereby, it can detect the roll angle θ of the vehicle without using a detection means whose cost burden is large. In addition, an apparatus 13 for the prevention of a roll reduces the output of an engine and operates a braking device when the vehicle is in danger of the roll on the basis of roll angle information on the estimated roll angle θ. Thereby, the progress of the roll is suppressed, and it is possible to prevent the roll of the vehicle at low costs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for estimating a roll angle of a vehicle for estimating a roll angle at the time of turning of a vehicle from lateral acceleration, and a rollover prevention apparatus using the apparatus.

[0002]

2. Description of the Related Art It is known that an automobile (vehicle) bends outward due to centrifugal force when turning. For this reason, when the vehicle performs a sharp turning operation and the force for inclining outward exceeds the ground contact force, the wheels inside the turning lift from the road surface and roll over.

In particular, vehicles having a high center of gravity, or vehicles such as trucks and buses whose center of gravity varies greatly depending on the load and the number of occupants have a low turning limit. Therefore, Japanese Patent Laid-Open No. 6-29
As disclosed in JP-A-7985, a ground displacement meter that directly detects the inclination of the vehicle body with respect to the road surface is employed, and the roll angle of the vehicle is calculated from the detection output of the ground displacement meter to prepare for the rollover of the vehicle. Or using a roll angle sensor (inclinometer) for detecting the inclination of the vehicle body as disclosed in Japanese Utility Model Application Laid-Open No. 3-110903, and detecting the actual roll angle of the vehicle from the detection output of the roll angle sensor. 2. Description of the Related Art In order to prevent a vehicle from rolling over, it has been performed.

[0004]

By the way, in recent years, where low cost is desired, it is required that the roll angle of a vehicle be determined at a low cost. However, both the former and the latter require dedicated special detection means such as a device or a sensor for directly detecting the roll angle, and thus have a problem that the cost is high. There is a need for detection.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle roll angle estimating apparatus and a vehicle roll angle estimating apparatus capable of detecting a vehicle roll angle without requiring special detecting means. An object of the present invention is to provide a rollover prevention device used.

[0006]

According to a first aspect of the present invention, there is provided an apparatus for estimating a roll angle of a vehicle, wherein the lateral acceleration detecting means detects when the vehicle is turning or the like. The lateral acceleration is affected not only by the actual lateral acceleration but also by the roll angle of the vehicle, and the actual lateral acceleration not affected by the roll angle can be theoretically estimated from the vehicle speed and the yaw rate. Focusing on the knowledge that the vehicle roll angle is estimated based on the lateral acceleration of the vehicle detected by the lateral acceleration detecting means and the estimated lateral acceleration estimated based on the vehicle speed and the yaw rate, the cost burden is reduced. The roll angle of the vehicle is detected properly without the need for a large special detecting means.

According to a second aspect of the invention, there is provided a vehicle rollover prevention device.
Further, the configuration according to claim 1 is provided with a safety measure executing means for taking safety measures for preventing the vehicle from rolling over, and the safety is established when the information amount based on the roll angle information estimated by the roll angle estimation means becomes a predetermined reference. The measure execution means is activated to prevent the vehicle from rolling over at low cost.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in FIGS. In FIG. 1, reference numeral 1 denotes a vehicle (vehicle) on which a driving engine, for example, a diesel engine 2 is mounted, and 3 denotes a roll angle estimating device mounted on the vehicle 1.

The roll angle estimating device 3 has a controller 4 composed of, for example, a microcomputer. The controller 4 includes, as vehicle speed detecting means for detecting the vehicle speed of the vehicle 1, for example, a wheel speed sensor 6 for detecting the wheel speed of the left front wheel of the vehicle, a wheel speed sensor 7 for detecting the wheel speed of the right front wheel, A wheel speed sensor 8 for detecting the wheel speed of the rear wheel and a wheel speed sensor 9 for detecting the wheel speed of the right rear wheel are also connected.

The controller 4 includes a lateral acceleration sensor 10 (corresponding to a lateral acceleration detecting means) for detecting a lateral acceleration acting on the automobile 1, and a yaw rate sensor 11 (corresponding to a yaw rate detecting means) for detecting a yaw rate acting on the automobile 1. ) Is connected.

The controller 4 can estimate the roll angle of the vehicle 1 based on the detection outputs of the wheel speed sensors 6 to 9, the lateral acceleration sensor 10, and the yaw rate sensor 11 according to the knowledge obtained by the present inventors. It is.

Here, the knowledge obtained by the inventors is that the lateral acceleration of the vehicle detected by the lateral acceleration detecting means at the time of turning the vehicle body is affected not only by the actual lateral acceleration but also by the roll angle of the vehicle. In addition, the actual lateral acceleration not affected by the roll angle can be theoretically estimated from the vehicle speed and the yaw rate.

In other words, the lateral acceleration detected by the lateral acceleration detecting means is only a net lateral acceleration if the vehicle body 1a turns without tilting, but actually the vehicle body 1a is provided via a suspension device, tires and the like. Since the vehicle body 1a is in contact with the road surface, the vehicle body 1a rolls under the influence of centrifugal force as the vehicle turns. For this reason, the value of the lateral acceleration detected by the lateral acceleration detecting means attached to the vehicle body 1a is increased by the influence of the gravitational acceleration caused by the roll.

That is, the output detected by the lateral acceleration detecting means when the vehicle is rolling is obtained by synthesizing the vehicle width direction acceleration component caused by the actual lateral acceleration during turning and the vehicle width direction acceleration component caused by the gravitational acceleration. Output.

[0015] More specifically, the actual lateral acceleration during turning of the vehicle is estimated based on the turning state of the vehicle, specifically, the vehicle speed and the yaw rate. In other words, when the vehicle is making a circular turn, the lateral acceleration (m / s)
² ) is represented by Gy ′ = R · ω ² (1). The vehicle speed V at this time is represented by V = R · ω (2).

However, R: turning radius (m), ω: yaw rate (rad / s). Therefore, the equation (2) is transformed into R = V / ω,
When combined with the equation (1), the estimated lateral acceleration Gy 'is estimated from the given equation Gy' = V.omega. (3), that is, the product of the vehicle speed and the yaw rate.

At this time, when the vehicle body 1a is tilted at the roll angle θ in the roll direction as shown by the two-dot chain line in FIG. 1, the position of the center of gravity H changes, and the output from the lateral acceleration detecting means attached to the vehicle body 1a is changed. The detected lateral output Gy (m / s ² ) is obtained by adding the vehicle width direction acceleration component Gy ′ cos θ of the actual lateral acceleration Gy ′ to the vehicle width direction acceleration component g sin θ of the gravitational acceleration g from the sensor output value. It is understood that it is done.

That is, Gy = Gy'cosθ + g sinθ
Is output. However, g: gravity acceleration (9.8m / s
² ). Here, in the range where θ is small, cos θ is set to approximately 1, Gy = Gy ′ + g sin θ, and when this is transformed into the equation of roll angle θ, θ = sin ⁻¹ (Gy−Gy ′ / g)
(4), the estimated lateral acceleration Gy 'and the detected acceleration G
The roll angle is estimated from y.

Therefore, the controller 4 includes the vehicle speed V detected from the wheel speed sensors 6 to 9 and the yaw rate sensor 1.
A function of calculating the estimated lateral acceleration Gy 'from the above equation (3) using the yaw rate ω from 1 (corresponding to a lateral acceleration estimating means), the calculated estimated acceleration Gy' and the lateral acceleration sensor 1
A function (corresponding to a roll angle estimating means) for calculating the roll angle θ from the above equation (4) using the detected lateral acceleration Gy detected from 0 is set so that the roll angle can be indirectly estimated. It is.

The controller 4 includes, for example, a deceleration means as a means for taking safety measures in preparation for rollover of the vehicle, specifically, the electronic governor 2a of the diesel engine 2, an automatic brake device 12 (each of which corresponds to a safety measure execution means). Are connected, and constitute a rollover prevention device 13 using the roll angle estimation device 3.

That is, the controller 4 has a function of making two rollover prevention determinations, more specifically, it is determined whether or not the estimated roll angle θ is equal to or greater than a predetermined roll angle value that may cause the vehicle to roll over. A function is set to determine whether or not the estimated roll angular velocity θ ′ calculated based on the estimated roll angle θ is equal to or higher than a predetermined roll angular velocity that may cause the vehicle to roll over. When an estimated roll angle θ and an estimated roll angular velocity θ ′ exceeding these criteria are detected, the controller 4 controls the electronic governor 2a so as to reduce the output of the diesel engine 2, and also reduces the vehicle speed of the automobile. A function of operating the automatic brake device 12 is set so that when the vehicle turns, when a sign of rollover occurs, the force in the yaw direction of the vehicle causing the rollover is reduced to prevent the rollover. .

The operation of the roll angle estimating device 3 and the rollover preventing device 13 is shown in the flowchart of FIG.
Next, the operation will be described with reference to this flowchart. It is assumed that the car 1 is running on the road now.

The controller 4 reads the wheel speeds VFL, VFR, VRL, VRR of the respective wheels (front left / right wheels / rear right / left wheels) from the respective wheel speed sensors 6 to 9 in step S 1, and calculates the lateral acceleration Gy from the lateral acceleration sensor 10. Then, the yaw rate ω is read from the yaw rate sensor 11 and the subsequent step S
In 2, the vehicle speed V is calculated from each wheel speed VFL, VFR, VRL, VRR.

At this time, it is assumed that the vehicle turns, for example, to the left, and the vehicle body 1a is inclined in the roll direction as shown by a two-dot chain line in FIG. Then, in step S3, an estimated lateral acceleration Gy 'is obtained from the wheel speed and the yaw rate based on the given expression "Gy' = V. [Omega]". In the subsequent step S4, ".theta. = Sin- ¹ (Gy-Gy '/ g). ) "
From the estimated lateral acceleration Gy ′ and the actual lateral acceleration Gy that is the output value of the lateral acceleration sensor 10, the vehicle 1
The inclination of a in the roll direction, that is, the estimated roll angle θ is obtained.

Thus, the roll angle of the vehicle can be properly detected without using special detecting means having a large burden such as a ground displacement meter and a roll angle sensor. On the other hand, whether the estimated roll angle θ is equal to or larger than a predetermined roll angle at which danger of causing the vehicle to roll over in step S6, or the roll angular velocity θ ′ (calculated in step S5) obtained from the estimated roll angle θ in step S7 is the rollover of the vehicle If the rotational speed is equal to or higher than the predetermined roll angular velocity that may cause the danger, the controller 4 determines that there is a tendency to roll over, proceeds to step S8, controls the electronic governor 2a to reduce the engine output, and activates the automatic brake device 12. Action is taken.

Then, the yaw force of the vehicle causing the rollover is reduced, and the progress of the rollover thereafter is suppressed, and the vehicle body 1a which is about to rollover returns. Therefore, the rollover of the vehicle can be prevented beforehand by using the roll angle information such as the estimated roll angle θ and the estimated roll angular velocity θ ′.

In addition, since both roll angle estimation and rollover prevention can be performed by an inexpensive detection system such as a wheel speed sensor or a yaw rate sensor, the cost is low. In one embodiment, it is determined whether or not there is a danger of rollover using both the estimated roll angle and the estimated roll angular velocity. However, the present invention is not limited to this, and the estimated roll angle, the estimated roll angular velocity The determination may be made using only one of the above.

As the safety measure executing means, the deceleration means for reducing the engine output and activating the automatic brake device is used. However, the present invention is not limited to this. The yaw control is performed by controlling the braking force difference or the driving force difference between a plurality of wheels. However, control of rear wheel steering, roll control, or a structure combining a plurality of these may be used. Needless to say, an alert for notifying the rollover tendency may be combined.

Further, in one embodiment, the electronic governor of the diesel engine is controlled to reduce the engine output. However, it is also possible to control the fuel injection amount, intake air amount, ignition timing and the like of the gasoline engine.

[0030]

As described above, according to the roll angle estimating apparatus according to the first aspect, the lateral acceleration detected by the lateral acceleration detecting means, the lateral acceleration estimated based on the vehicle speed and the yaw rate are used. , The roll angle of the vehicle can be estimated.

Therefore, the roll angle can be appropriately estimated without the need for a special detecting means having a large cost burden.
The roll angle can be detected at low cost. According to the rollover prevention device of the second aspect, in addition to the effect of the first aspect, in a dangerous situation in which the vehicle rolls over, a safety measure for preventing the vehicle from rolling over based on roll angle information obtained from the estimated roll angle. Therefore, it is possible to prevent the vehicle from rolling over at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a configuration of a roll angle estimation device and a rollover prevention device using the device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of each device for estimating a roll angle and preventing rollover.

[Explanation of symbols]

2a, 11: electronic governor, automatic brake device (safety measure execution means) 4: controller (lateral acceleration estimation means, roll angle estimation means, control means) 6-9: wheel speed sensor (vehicle speed detection means) 10: lateral acceleration sensor (Lateral acceleration detecting means) 11 ... Yaw rate sensor (yaw rate detecting means).

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kunio Sakata 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation

Claims (2)

[Claims] 1. A lateral acceleration detecting means for detecting a lateral acceleration of a vehicle, a vehicle speed detecting means for detecting a vehicle speed, a yaw rate detecting means for detecting a yaw rate generated in the vehicle, and a vehicle speed detected by the vehicle speed detecting means. Lateral acceleration estimating means for estimating a lateral acceleration based on the yaw rate detected by the yaw rate detecting means; and a lateral acceleration detected by the lateral acceleration detecting means and a lateral acceleration estimated by the lateral acceleration estimating means. And a roll angle estimating means for estimating the roll angle of the vehicle. 2. A lateral acceleration detecting means for detecting a lateral acceleration of a vehicle, a vehicle speed detecting means for detecting a vehicle speed, a yaw rate detecting means for detecting a yaw rate generated in the vehicle, and a safety measure for preventing the vehicle from rolling over. Safety measure executing means for taking a measure, a lateral acceleration estimating means for estimating a lateral acceleration based on a vehicle speed detected by the vehicle speed detecting means and a yaw rate detected by the yaw rate detecting means, Roll angle estimating means for estimating the roll angle of the vehicle based on the lateral acceleration estimated by the lateral acceleration estimating means, and an information amount based on the roll angle information estimated by the roll angle estimating means. Control means for activating the safety measure execution means when the standard is met.