JP4250013B2 - Road surface state determination device and method, and road surface state determination program - Google Patents

Description

【００３４】
図４にそれぞれの路面における平均変動量ｍｓｖの値の経時変化を示す。図４において、Ｒ１はアイスバーンの路面の場合、Ｒ２は圧雪された路面の場合、Ｒ３はアスファルトの路面の場合の変動量ｍｓｖを示す。
【００３５】
図４より明らかなように、路面状態により、平均変動量ｍｓｖに違いが現われており、具体的には、アイスバーンの路面の場合の曲線Ｒ１は、表１の極低μ路のしきい値の範囲にほぼ対応し、同様に、圧雪路面の場合の曲線Ｒ２は、低μ路のしきい値の範囲にほぼ対応し、アスファルトの路面の場合の曲線Ｒ３は、高μ路のしきい値の範囲にほぼ対応している。したがって、この判定実験では、３種類の路面状態を正確に判定することができた。
【００３６】
【発明の効果】
本発明によれば、車両の絶対速度を用いることなく車輪回転速度情報のみから走行中の路面状態を正確に判別することができ、従動輪のない四輪駆動車などにも広く適用することができる。
【図面の簡単な説明】
【図１】本発明の路面状態判定装置の一実施の形態を示すブロック図である。
【図２】図１における路面状態判定判定装置の電気的構成を示すブロック図である。
【図３】本発明の路面状態判定方法の一実施の形態を示すフローチャートである。
【図４】図３の路面状態判定方法によって求められた３種類の路面状態における平均変動量の時間的変化を示すグラフである。
【符号の説明】
１ 制御ユニット
２ 警報表示器
３ 初期化スイッチ
ＦＬＷ、ＦＲＷ、ＲＬＷ、ＲＲＷ タイヤ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a road surface state determination device and method, and a road surface state determination program. More specifically, the present invention relates to a road surface state determination device that determines the slipperiness between a running tire and a road surface, and more particularly to a road surface state determination device and method that can be applied to a four-wheel drive vehicle, and a road surface state determination program. .
[0002]
[Prior art]
In a conventional method for determining a road surface condition during traveling of a vehicle, it is important to obtain an absolute speed of the vehicle in order to determine a motion state of the vehicle and a road surface state during traveling.
[0003]
As a method for obtaining the absolute speed of the vehicle, for example, in the case of a two-wheel drive vehicle, the rotational speed of the driven wheel without driving force can be used as the absolute speed of the vehicle (see, for example, Patent Document 1).
[0004]
As another method, the absolute speed of the vehicle can be estimated from the output value of the acceleration sensor.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-253334
[Problems to be solved by the invention]
However, the former method has a problem that a four-wheel drive vehicle in which driving force is applied to all four wheels cannot be used because there are no driven wheels.
[0007]
Further, the latter method has a problem that there are many error factors due to the influence of the road surface gradient, and it is difficult to estimate with high accuracy.
[0008]
Therefore, because of these problems, it is very difficult to accurately determine the absolute speed of the vehicle in the case of a four-wheel drive vehicle, and the road surface condition determination method using the absolute speed of the vehicle is inferior in accuracy. Currently.
[0009]
The present invention has been made to solve such a problem, and can determine a road surface state without using an absolute vehicle speed, and can be applied to a four-wheel drive vehicle. An object is to provide a state determination program.
[0010]
[Means for Solving the Problems]
The road surface condition determination device of the present invention includes (a) a wheel rotation speed detection means for determining a wheel rotation speed of each wheel of the vehicle,
(B) a turning radius calculating means for obtaining a turning radius when the vehicle turns;
(C) a wheel rotation speed ratio calculating means for calculating a wheel rotation speed ratio between the left wheel and the right wheel for each of the front and rear wheels when the turning radius is equal to or greater than a predetermined value;
(D) a fluctuation amount calculating means for calculating a fluctuation amount of the rotation speed ratio;
And (e) determination means for determining a road surface state from the magnitude of the fluctuation amount.
[0011]
The road surface condition determination method of the present invention includes: (a) a wheel rotation speed detection step for determining a wheel rotation speed of each wheel of the vehicle;
(B) a turning radius calculating step for obtaining a turning radius when the vehicle turns;
(C) a wheel rotation speed ratio calculating step of calculating a wheel rotation speed ratio between the left wheel and the right wheel for each of the front wheel and the rear wheel when the turning radius is equal to or greater than a predetermined value;
(D) a fluctuation amount calculating step of calculating a fluctuation amount of the rotation speed ratio;
And (e) a determination step of determining a road surface state from the magnitude of the fluctuation amount.
[0012]
The road surface state determination program of the present invention includes a computer for determining a road surface state, (b) a turning radius calculation means for obtaining a turning radius when the vehicle turns, and (c) a turning radius of the vehicle equal to or greater than a predetermined value. A wheel rotation speed ratio calculating means for calculating a wheel rotation speed ratio between the left wheel and the right wheel for each of the front wheel and the rear wheel, and (d) a fluctuation amount calculating means for calculating a fluctuation amount of the rotation speed ratio. And (e) functioning as a determination means for determining the road surface state from the magnitude of the fluctuation amount.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, a road surface state determination apparatus and method and a road surface state determination program of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a road surface condition judging device of the present invention, FIG. 2 is a block diagram showing an electrical configuration of the road surface condition judging device in FIG. 1, and FIG. 3 is a road surface condition judging method of the present invention. FIG. 4 is a flow chart showing an embodiment of the present invention, and FIG. 4 is a graph showing temporal changes in the average fluctuation amount in the three types of road surface states determined by the road surface state determination method of FIG.
[0014]
In general, when a vehicle travels on a road surface in various states, a low μ road has a higher probability of different road surface conditions through which the left and right tires pass than a high μ road, and a difference tends to appear in the left and right wheel rotation behavior. It is in. The road surface state determination device of the present invention made by paying attention to this phenomenon determines the road surface state only from the fluctuation amount of the left / right rotation speed ratio without using the absolute speed as in the prior art. In addition, it can be applied to a four-wheel drive vehicle having no driven wheel.
[0015]
That is, as shown in FIG. 1, the road surface condition determining apparatus according to an embodiment of the present invention periodically determines the rotational speeds of the wheel tires provided in the tires FLW, FRW, RLW and RRW of the four-wheel drive vehicle. Rotational speed detecting means S for detecting the rotational speed is provided, and the output of the rotational speed detecting means S is transmitted to a control unit 1 such as ABS. Further, as shown in FIG. 2, the control unit 1 is connected with an alarm indicator 2 which is a display means constituted by a liquid crystal display element, a plasma display element or a CRT. Reference numeral 3 denotes an initialization switch operated by the driver.
[0016]
The rotational speed detecting means S generates a rotational pulse by using an electromagnetic pickup or the like and generates power using rotation like a wheel speed sensor or dynamo that measures the rotational speed from the number of pulses. An angular velocity sensor including one that measures the rotational speed can be used.
[0017]
As shown in FIG. 2, the control unit 1 stores an I / O interface 1a necessary for signal exchange with an external device, a CPU 1b functioning as a center of arithmetic processing, and a control operation program for the CPU 1b. The ROM 1c and the RAM 1d from which data or the like is temporarily written when the CPU 1b performs a control operation or from which the written data is read out.
[0018]
The control operation program of the CPU 1b includes, for example, a computer for determining a road surface state, turning radius calculation means for obtaining a turning radius when the vehicle turns, and a front wheel and a rear wheel when the turning radius of the vehicle is a predetermined value or more. For each wheel, a wheel rotation speed ratio calculation means for calculating a wheel rotation speed ratio between the left wheel and the right wheel, a fluctuation amount calculation means for calculating a fluctuation amount of the rotation speed ratio, and a magnitude of the fluctuation amount It functions as a determination means for determining the road surface condition.
[0019]
The road surface condition determination method for a four-wheel drive vehicle according to the present embodiment is executed, for example, according to the flowchart shown in FIG.
[0020]
(1) First, the wheel speed is calculated from the signal of the wheel speed sensor provided on each wheel, and the wheel rotational speeds v1, v2, v3, v4 of the left front wheel, right front wheel, left rear wheel and right rear wheel are calculated. Obtained (step S1).
[0021]
(2) Next, the turning radius of the vehicle is obtained (step S2). The turning radius may be obtained from a rudder angle sensor (not shown) or may be obtained by calculating from the wheel rotation speeds of the left and right wheels and the vehicle tread width.
[0022]
(3) When the turning radius is equal to or greater than a predetermined value (for example, 100 m), the left and right wheel ratio sf of the front wheel and the left and right wheel ratio sr of the rear wheel are calculated according to the following equations (1) and (2), respectively (steps S3 to S3). S4).
[0023]
sf _n = vl _n / v2 _n (1)
sr _n = v3 _n / v4 _n (2)
[0024]
(4) Next, the fluctuation amount sfv of the front wheel left / right wheel ratio and the fluctuation amount srv of the rear wheel left / right wheel ratio are calculated according to the following equations (3) and (4), respectively (step S5).
[0025]
sfv _n = ABS (sf _n −sf _n−1 ) (3)
srv _n = ABS (sr _n −sr _n−1 ) (4)
[0026]
(5) The sum of the fluctuation amounts of the front and rear wheels is calculated according to the following equation (5) (step S6).
[0027]
sv _n = sfv _n + srv _n (5)
[0028]
▲ 6 ▼ The obtained performs averaging processing for the sum sv _n of variation, calculates the average variation msv (step S7).
[0029]
(7) If the average fluctuation amount msv is larger than a threshold value set in advance for each vehicle, it is determined that the road surface is slippery (steps S8 to S9). For example, the threshold is determined in advance by performing a test for each vehicle.
[0030]
Based on the determination result obtained as described above, an alarm is issued to the driver using a buzzer or the like, or vehicle motion control is performed.
[0031]
【Example】
Next, using the road surface condition determination method of the present embodiment, an experiment for determining different road surface conditions was performed. The experimental conditions are as follows.
[0032]
a) A four-wheel drive vehicle ran on asphalt roads, snow-capped roads, and ice-burn roads.
b) The wheel sampling time is 0.04 seconds.
c) The turning radius is the same as the value obtained from the wheel speed and tread width of the front wheel averaged over 0.6 seconds, and the value obtained from the wheel speed and tread width of the rear wheel averaged over 0.6 seconds is further averaged. It was calculated.
d) The average fluctuation amount msv when the turning radius is 100 m or more was obtained.
e) The threshold values were set as shown in Table 1 below.
[0033]
[Table 1]

[0034]
FIG. 4 shows the change over time of the value of the average fluctuation amount msv on each road surface. In FIG. 4, R1 represents the fluctuation amount msv in the case of an ice burn road surface, R2 in the case of a snow-capped road surface, and R3 in the case of an asphalt road surface.
[0035]
As apparent from FIG. 4, the average fluctuation amount msv differs depending on the road surface condition. Specifically, the curve R1 in the case of the ice burn road surface is the threshold value of the extremely low μ road in Table 1. Similarly, the curve R2 in the case of a snowy road surface substantially corresponds to the threshold range of the low μ road, and the curve R3 in the case of an asphalt road surface is the threshold value of the high μ road. Almost corresponds to the range. Therefore, in this determination experiment, three types of road surface conditions could be determined accurately.
[0036]
【The invention's effect】
According to the present invention, it is possible to accurately determine the road surface state during traveling from only the wheel rotational speed information without using the absolute speed of the vehicle, and it can be widely applied to four-wheel drive vehicles without driven wheels. it can.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a road surface condition judging device of the present invention.
FIG. 2 is a block diagram showing an electrical configuration of the road surface condition determination / judgment apparatus in FIG. 1;
FIG. 3 is a flowchart showing an embodiment of a road surface condition determination method of the present invention.
4 is a graph showing temporal changes in average fluctuation amounts in three types of road surface states determined by the road surface state determination method of FIG. 3;
[Explanation of symbols]
1 Control unit 2 Alarm display 3 Initialization switch FLW, FRW, RLW, RRW Tire

Claims (3)

(A) wheel rotation speed detection means for determining the wheel rotation speed of each wheel of the vehicle;
(B) a turning radius calculating means for obtaining a turning radius when the vehicle turns;
(C) a wheel rotation speed ratio calculating means for calculating a wheel rotation speed ratio between the left wheel and the right wheel for each of the front and rear wheels when the turning radius is equal to or greater than a predetermined value;
(D) a fluctuation amount calculating means for calculating a fluctuation amount of the rotation speed ratio;
(E) A road surface state determination device comprising determination means for determining a road surface state from the magnitude of the fluctuation amount. (A) a wheel rotation speed detection step for determining a wheel rotation speed of each wheel of the vehicle;
(B) a turning radius calculating step for obtaining a turning radius when the vehicle turns;
(C) a wheel rotation speed ratio calculating step of calculating a wheel rotation speed ratio between the left wheel and the right wheel for each of the front wheel and the rear wheel when the turning radius is equal to or greater than a predetermined value;
(D) a fluctuation amount calculating step of calculating a fluctuation amount of the rotation speed ratio;
(E) a road surface state determination method including a determination step of determining a road surface state from the magnitude of the fluctuation amount. A computer for determining the road surface condition; (b) a turning radius calculation means for obtaining a turning radius when the vehicle turns; and (c) when the turning radius of the vehicle is a predetermined value or more, for each of the front wheels and the rear wheels. Wheel rotational speed ratio calculating means for calculating the wheel rotational speed ratio between the left wheel and the right wheel, (d) fluctuation amount calculating means for calculating the fluctuation amount of the rotational speed ratio, and (e) the fluctuation amount of the fluctuation amount. A road surface state determination program for functioning as a determination unit for determining a road surface state from a size.

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