JPH10300481A - Vehicle running state control device and method using map data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle running control device and method using map data, ensuring running control even on a curve where a longitudinal gradient is present. SOLUTION: Data about the configuration of a curved road present on the expected route of a vehicle are acquired from a current position acquisition device 12 and a map database 14. An arithmetic control unit 18 computes, from data about longitudinal and cross gradients contained in the configuration data, longitudinal and lateral forces applied to the front and rear wheels, and computes a maximum frictional force that can be generated, from the friction coefficient μ of the road surface acquired by a road surface μ acquisition device 16 and from the vertical-to-road-surface component of load applied to the front and rear wheels. An excess lateral force is calculated from the longitudinal and lateral forces and the maximum frictional force, a lateral force that is permitted to be generated in the vehicle is calculated, and a desired vehicle velocity V is computed on the basis of it. Based on the desired vehicle velocity V, the velocity of the vehicle is controlled by means of a decelerator 20 and an alarm device 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle control system using map data for acquiring data relating to the shape of a road on an expected course of a vehicle, and controlling the vehicle speed or warning the vehicle speed adjustment based on the data.

[0002]

2. Description of the Related Art Hitherto, a device has been proposed which acquires the shape of a road ahead of an own vehicle from a map database and controls the vehicle speed so that the vehicle can travel smoothly on a curve existing ahead. Japanese Patent Application Laid-Open No. H8-202991 discloses such a technique. In this conventional example, when determining the target vehicle speed at a curve, the lateral force of the road surface, the vehicle lateral force due to the longitudinal gradient, the longitudinal force are subtracted from the friction coefficient μ of the road surface, or the lateral force is added depending on the direction of the transverse gradient. Then, a margin of the lateral force is calculated, and the target vehicle speed is calculated by balancing the margin of the lateral force with the centrifugal force of the curve. Here, the target vehicle speed is

(Equation 1) It is calculated by:

[0003]

However, when the curve through which the vehicle passes has a longitudinal gradient, the wheel loads on the front and rear wheels are not equal. Therefore, when the vehicle is controlled based on the lateral force margin determined based on the two-dimensional model as in the conventional example, there is a possibility that even at the target vehicle speed, the wheel with a small wheel load may exceed the limit of the frictional force. There is.
The driver normally controls acceleration and deceleration by taking into account the vertical gradient that he or she sees to some extent. However, if the above control is performed, the driver may not agree with the driver's feeling. was there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a vehicle travel control device and a map data utilization control system using map data for enabling reliable travel control even on a curve having a longitudinal gradient. It is an object of the present invention to provide a vehicle traveling control method.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a vehicle driving control apparatus using map data, which is capable of generating shape data including a vertical gradient of a curved road on an expected course of a vehicle. Means for acquiring, when entering a curve, estimated frictional force acquiring means for calculating an estimated frictional force for each of the front wheels and rear wheels of the own vehicle based on the shape data based on the shape data, and when entering the curve To
A means for estimating the longitudinal force and lateral force generated for each of the front and rear wheels of the vehicle based on the shape data, and estimating the lateral force margin that can be generated for the vehicle from the estimated friction force, longitudinal force, and lateral force Means for calculating, and vehicle speed control means for controlling the own vehicle speed so that the lateral force generated in the own vehicle when passing through the curve converges to the lateral force margin or less, or issuing a vehicle speed adjustment warning to the driver, It is characterized by having.

Further, in the vehicle traveling control apparatus using map data according to the present invention, a lateral force margin is calculated for a wheel having a smaller value among estimated friction forces obtained for each of a front wheel and a rear wheel. I do.

Further, in the vehicle driving control apparatus using map data according to the present invention, the shape data is acquired from the on-vehicle navigation system, and the vehicle speed control means controls the own vehicle speed in consideration of the positional relationship between the own vehicle position and the curve. Alternatively, a warning is issued to the driver to adjust the vehicle speed.

Further, in order to achieve the above object, the present invention relates to a vehicle driving control method using map data, comprising obtaining shape data including a vertical gradient of a curved road on an expected course of a vehicle, and When entering the vehicle, the estimated frictional force is calculated for each of the front and rear wheels of the own vehicle based on the shape data based on the shape data, and when entering the curve, the front and rear wheels of the own vehicle are calculated based on the shape data. The longitudinal force and the lateral force generated for each wheel are estimated and calculated. From the estimated frictional force, the longitudinal force and the lateral force, a lateral force margin that can be generated in the own vehicle is estimated and calculated, and when the vehicle passes the curve, The vehicle speed is controlled so that the lateral force generated in the vehicle converges to the lateral force margin or less, or a warning of the vehicle speed adjustment is issued to the driver.

Further, in the vehicle traveling control method using map data according to the present invention, a lateral force margin is calculated for a wheel having a smaller value among estimated friction forces obtained for each of a front wheel and a rear wheel. I do.

In the vehicle traveling control method using map data according to the present invention, the shape data is obtained from an on-vehicle navigation system, and the vehicle speed is controlled in consideration of the positional relationship between the vehicle position and the curve, or A vehicle speed adjustment warning is issued.

[0011]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a vehicle driving control device using map data according to the present invention. In FIG. 1, a vehicle speed is detected by a wheel speed sensor 10. Further, data such as a road shape stored in the map database 14 is read according to the current position of the vehicle acquired by the current position acquisition device 12. The data such as the road shape includes data such as a vertical slope and a cross slope. The current position acquisition device 12 is configured to acquire the current position from, for example, a GPS or the like. The map database 14 may be, for example, an in-vehicle navigation system. Alternatively, a telephone line may be connected to an external map data storage center, and map data may be taken online into a vehicle-mounted memory such as a DVD or a CD-ROM.

The road surface μ obtaining device 16 obtains the friction coefficient μ of the road surface of the road on which the vehicle runs. The road surface μ obtaining device 16 is a device that obtains a road surface friction coefficient μ by, for example, calculation from an information network such as an infrastructure, a database stored in advance, or various sensors. As described above, the current position acquisition device 12, the map database 14,
The road surface μ acquiring device 16 constitutes a shape data acquiring unit according to the present invention.

The vehicle speed and current position acquisition device 12 acquired by the wheel speed sensor 10 and the map database 1
4. The shape data of the road including the curve on the expected course of the vehicle acquired by the road surface μ acquiring device 16 is input to the arithmetic processing device 18. The arithmetic processing unit 18 calculates the load acting on each of the front wheel and the rear wheel of the own vehicle based on the vertical gradient and the cross gradient included in the shape data in the curve on the expected course of the own vehicle. Further, an estimated friction force is calculated for each of the front wheel and the rear wheel using the load and the friction coefficient μ of the road surface. In addition, the arithmetic processing unit 18
The longitudinal force and the lateral force generated for each of the front wheel and the rear wheel of the own vehicle are also estimated and calculated based on the shape data of the predicted course. Further, from the estimated friction force, the longitudinal force, and the lateral force, a value obtained by vectorially subtracting the lateral force margin that can be generated in the vehicle, that is, the resultant force of the longitudinal force and the lateral force, from the estimated friction force is calculated. . The arithmetic processing device 18 controls the vehicle speed by controlling the own vehicle speed by the reduction gear device 20 based on the lateral force margin obtained in this way, or by issuing a vehicle speed adjustment warning to the driver by the alarm device 22. It is configured to perform.

FIG. 2 shows a flow of an operation for smoothly traveling on a curve by the map data utilization vehicle traveling control device shown in FIG. FIG. 3 is an explanatory diagram of the distribution of loads applied to the front wheels and the rear wheels when the vehicle is located on a road having a vertical gradient. FIG. 4 is an explanatory diagram of distribution of the load applied to the front wheels when the vehicle is located on a road having a cross slope. The load applied to the rear wheel is the same, so that the illustration is omitted.

In FIG. 2, it is determined from the current position acquiring device 12 and the map database 14 whether or not a curve exists near the front on the predicted course of the vehicle (S1). If a curve exists, it is determined whether or not the curve has a vertical gradient based on information in the map database 14 (S2).

When there is a curved road having a vertical gradient on the predicted course of the vehicle, the wheel loads of the front and rear wheels, that is, the forces Ffw and Frw in the direction perpendicular to the road surface, are calculated by the arithmetic processing unit 1.
8 (S3). The wheel load Ffw of the front and rear wheels,
Frw is, as shown in FIG. 3, a component of gravity applied to the front wheel and the rear wheel in a direction perpendicular to the road surface. The load applied to the front wheels and the rear wheels changes according to the position of the center of gravity of the vehicle. That is, more load is applied to the wheel closer to the center of gravity.

The value obtained by multiplying the wheel loads Ffw and Frw of the front and rear wheels obtained as described above by the friction coefficient μ of the road surface is the maximum frictional force that can be generated in each wheel. Further, road surface direction components Ffx, Frx of gravity applied to the front wheels and the rear wheels.
Is the longitudinal force based on the gravity generated in each wheel.

Further, as shown in FIG. 4, when the road has a cross slope, the road surface direction components Ffy and Fry of the gravitational force applied to the front wheels and the rear wheels become lateral forces generated based on the gravity. . In this case, the wheel loads Ffw and Frw applied to the front and rear wheels are also reduced by the amount of the lateral force.

FIG. 5 shows a circle of the maximum possible friction force Ffw × μ described above. Further, the longitudinal force and the lateral force simultaneously generated on the front wheels are also shown. FIG. 5 shows the relationship between the forces at the front wheels, but the same can be applied to the rear wheels. The resultant force of the front-rear force Ffx and the lateral force Ffy generated on the front wheels is the maximum frictional force Ffw.
If it stays in the area inside the circle of × μ,
Since the grip force of the tire is larger than the resultant force, the tire does not slip. In this case, the lateral force has a margin by Fyf shown in FIG. This Fyf is hereinafter referred to as a lateral force margin.

The lateral force margin can be obtained from the maximum frictional force that can be generated at the front wheels and the rear wheels. That is, the maximum frictional force Ffw × μ that can be generated at the front wheels is
From FIG.

(Equation 2) And the maximum frictional force Fr that can be generated at the rear wheel
Similarly for w × μ

(Equation 3) Becomes In the above second and third formulas, the longitudinal force, the lateral force, and the lateral force margin generated at the front and rear wheels are expressed as vectors. These are determined by the direction of the vertical gradient and the cross gradient. Where Ffx
Is the longitudinal force applied to the front wheel by the longitudinal gradient, Frx is the longitudinal force applied to the rear wheel by the longitudinal gradient, Ffy is the lateral force applied to the front wheel by the transverse gradient, Fry is the lateral force applied to the rear wheel by the transverse gradient, Fyf is Fyr is equivalent to the front wheel margin.
This is the amount of lateral force margin for the rear wheels.

From the above-described equations (2) and (3), the lateral force margins Fyf and Fyr of the front and rear wheels are calculated by the processing unit 18 (S4).

Next, a lateral force that can be generated in the vehicle is obtained from each of the front wheel lateral force margin Fyf and the rear wheel lateral force margin Fyr based on the center of gravity of the vehicle (S5). That is, as shown in FIG. 6, when the distance from the center of gravity to the front wheel is lf, and the distance from the center of gravity to the rear wheel is lr,
From the lateral force margin Fyf at the front wheels, the vehicle lateral force Ff

(Equation 4) Can be obtained as Similarly, from the lateral force margin Fr on the rear wheels, the vehicle lateral force Fr is similarly calculated.

(Equation 5) Can be obtained as

As described above, the vehicle lateral force Ff, which is obtained from the lateral force margin Fyf, Fyr of the front wheel and the rear wheel, respectively.
A small value of Fr is set as the target lateral force F (S6). Using the target lateral force F, a target vehicle speed V for running smoothly on a curve in the arithmetic processing unit 18 is determined.

(Equation 6) (S7). Here, R is the curvature of the curve, which can be obtained from the map database 14. M is the weight of the vehicle.

Based on the target lateral force F or the target vehicle speed V obtained in the above steps, the arithmetic processing unit 18 can cause the speed reduction device 20 to perform deceleration control. Further, a warning such as adjusting the vehicle speed can be issued to the driver by the alarm device 22.

The above-described deceleration control of the vehicle speed or the vehicle speed adjustment warning is performed by the current position of the vehicle acquired by the current position acquisition device 12 and the current position of the vehicle in front of the vehicle determined based on the data in the map database 14. It is also preferable to perform the adjustment according to the positional relationship with the curve, that is, the distance. That is, looking at the difference between the current vehicle speed and the target vehicle speed V obtained by the wheel speed sensor 10, if this difference is small, it is possible to decelerate to the target vehicle speed V over a relatively short distance, but this difference is large. In this case, the distance required to decelerate to target vehicle speed V becomes longer. Therefore, the operation of the speed reducer 20 or the alarm device 22 can be controlled based on the distance to the curve, the current vehicle speed, and the target vehicle speed V.

When there is no longitudinal gradient, the target lateral force F and the target vehicle speed V are separately supplied from the front and rear wheels as described above.
Can be calculated as a one-wheel model instead of calculating.

According to the above-described method, it is possible to calculate the curve-passing target vehicle speed in consideration of the ratio of the load applied to the front wheels and the rear wheels when the front curve has a vertical gradient.

[0029]

As described above, according to the present invention,
Considering the longitudinal gradient on the expected course of the vehicle, comparing the front wheel load and the rear wheel load when traveling on a curve, and comparing with the reference value, that is, the maximum possible frictional force, based on the smaller wheel In addition, both the front wheels and the rear wheels can run without exceeding the allowable limit. For this reason, the driving | running | working close to a driver's image can be implement | achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a vehicle driving control device using map data according to the present invention.

FIG. 2 is a flowchart showing an operation of the embodiment shown in FIG. 1;

FIG. 3 is an explanatory diagram of load distribution applied to a front wheel and a rear wheel when a vehicle is located on a vertical gradient.

FIG. 4 is an explanatory diagram of load distribution on front wheels when the vehicle is located on a cross slope.

FIG. 5 is a diagram showing a relationship between a maximum frictional force that can be generated on a wheel, a longitudinal force, and a lateral force.

FIG. 6 is an explanatory diagram in a case where a target lateral force of a vehicle is obtained from a lateral force margin at a front wheel and a rear wheel.

[Explanation of symbols]

10 wheel speed sensor, 12 current position acquisition device, 14
Map database, 16 road surface μ acquisition device, 18 arithmetic processing device, 20 reduction gear, 22 alarm device.

Claims (6)

[Claims] 1. A means for acquiring shape data including a vertical gradient of a curved road on an expected course of the own vehicle, and when entering the curve, each of a front wheel and a rear wheel of the own vehicle based on the shape data. An estimated frictional force obtaining means for calculating an estimated frictional force for each of the applied loads, and a longitudinal force and a lateral force generated for each of a front wheel and a rear wheel of the own vehicle based on the shape data when the vehicle enters the curve. Means for estimating and calculating; means for estimating a lateral force margin that can be generated in the vehicle from the estimated frictional force, the longitudinal force and the lateral force; and a lateral force generated in the vehicle when passing through the curve. Vehicle speed control means for controlling the vehicle speed so as to converge to a value equal to or less than the lateral force margin or issuing a vehicle speed adjustment warning to the driver. 2. The vehicle driving control device using map data according to claim 1, wherein the lateral force margin is calculated for a wheel having a smaller value among estimated frictional forces obtained for each of a front wheel and a rear wheel. A vehicle travel control device using map data. 3. The vehicle travel control device using map data according to claim 1, wherein the shape data is obtained from an on-vehicle navigation system, and the vehicle speed control means determines a positional relationship between the own vehicle position and the curve. A vehicle travel control device using map data, wherein the vehicle speed is controlled in consideration of the vehicle speed, or a vehicle speed adjustment warning is issued to a driver. 4. Obtaining shape data including a vertical gradient of a curved road on an expected course of the own vehicle, and when entering the curve, acts on each of a front wheel and a rear wheel of the own vehicle based on the shape data. From the load, an estimated frictional force is calculated for each, and when the vehicle enters the curve, the longitudinal force and the lateral force generated for each of the front wheel and the rear wheel of the own vehicle are calculated based on the shape data, and the estimated frictional force is calculated. From the longitudinal force and the lateral force, a lateral force margin that can be generated in the own vehicle is estimated and calculated, so that the lateral force generated in the own vehicle when passing through the curve converges to the lateral force margin or less. A vehicle travel control method using map data, wherein the vehicle speed is controlled or a driver speed warning is issued to a driver. 5. The method according to claim 4, wherein the lateral force margin is calculated for a wheel having a smaller value among the estimated frictional forces obtained for each of the front wheel and the rear wheel. A vehicle traveling control method using map data. 6. The vehicle travel control method using map data according to claim 4, wherein the shape data is obtained from an on-vehicle navigation system, and the own vehicle is considered in consideration of a positional relationship between the own vehicle position and the curve. A vehicle driving control method using map data, comprising controlling a speed or issuing a vehicle speed adjustment warning to a driver.