JPS62118207A - Detector for road surface condition - Google Patents

Abstract

PURPOSE:To accurately detect the road surface conditions by statistical grasp by receiving reflected waves from a road of periodical transmission detection waves and discriminating the waves based on the frequency accumulation of reflection intensity exceeding a set value. CONSTITUTION:An ultrasonic oscillator 13 of a transmission and reception circuit 11 is controlled by a timer 23 of a control and arithmetic unit 21 and ultrasonic waves are transmitted periodically from a transmission horn 5 of a vehicle body to a road surface 29. Then, the ultrasonic reflected waves from the road surface 29 are received with a reception horn 9 and processed by a voltage detection circuit 17 and an A/D converter 19 and a reflected wave intensity digital signal is supplied to an arithmetic unit 25. Then, the unit 25 compares the reflected wave intensity digital signal with the set value and operates the frequency accumulation exceeding the set value and a discriminator 27 grasps the road surface conditions statistically and outputs discrimination signals of accurate road condition detection outputs of the concrete road, the rough asphalt road, the heavy snow road, the fresh snow road, etc., based on the operated result.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a road surface condition detection device used for detecting the condition of a traveling road surface from a vehicle.

[Technical Background of the Invention and Problems thereof] A road surface condition detection device has been proposed for automatically detecting road surface conditions.
See publication. Such conventional road surface condition detection devices statically detect whether the road surface is dry, wet, snowy, frozen, etc. using diffused reflection of light. For this reason, the detection is localized, and there is a problem in that false detection is likely to occur when the detected area is shoveled with snow but the entire road surface is covered in snow.

In order to solve such conventional technical problems, the applicant of the present application proposed a new road surface condition detection device in Japanese Patent Application No. 130985/1985. The road condition detection device
The time average and standard deviation of the reflected wave intensity of the detected wave transmitted toward the road surface from the transmitting means are calculated, and the road surface condition is determined from the combined characteristics of the two.

Although this prior invention is useful for accurately detecting road surface conditions, it has been desired to further improve the road surface condition detection device that can accurately distinguish between frozen roads and road surfaces with poor or deteriorated pavement conditions. .

[Purpose of the Invention] The present invention was developed to solve the above-mentioned conventional problem, and calculates the cumulative value of the frequency at which the reflected wave intensity exceeds a set value, and determines the road surface condition based on the frequency. It is an object of the present invention to provide a road surface condition detection device that can reliably detect road surface conditions by making judgments.

[Structure of the Invention] As shown in FIG. 1, the present invention includes a transmitting means for transmitting detection waves toward a road surface at a constant cycle, a receiving means for receiving reflected waves from the road surface, and a receiving means for receiving reflected waves from the receiving means. A wave intensity detection means, a calculation means for comparing the reflected wave intensity from the detection means with a set value and calculating a cumulative value of the frequency at which the set value is exceeded, and a determination means for determining the road surface condition from the output of the calculation means. The gist of the present invention is a road surface condition detection device comprising:

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be explained in detail based on the drawings. Second
The figure shows a circuit block diagram of an embodiment of the present invention.
The figure shows the equipment configuration. As shown in FIG. 3, a transmitting microphone 3 and a transmitting bone 5 as ultrasonic transmitting means are attached to a housing 1 that is attached to the body of an automobile, and a receiving microphone 7 and a receiving horn 9 as receiving means are attached.
is installed. Furthermore, the housing 1 has a transmitting/receiving circuit 11.
is included.

This transmitter/receiver circuit includes an ultrasonic oscillator 1 as shown in FIG.
3. It includes a received signal amplification circuit 15, a voltage detection circuit 17 of the amplification circuit, and an A/DI converter 19. This amplifier circuit 15, voltage detection circuit 17 and A/D converter 1
9 constitutes reflected wave intensity detection means.

The transmitting/receiving circuit 11 is connected to a control calculation device 21 .

This control calculation device 21 includes a timer 23 for the ultrasonic oscillator 13, a calculation device 25 for the detection signal from the reflected wave intensity detection means, and a determination device 27 for the calculation result of the calculation device 25.

The operation of the road surface condition detection device having the above configuration will now be explained based on the flowchart shown in FIG. The timer 23 of the control calculation device 21 controls the operation of the ultrasonic oscillator 13, and as shown in FIG.
A 12-hour oscillation pulse is sent out to the road surface 29 at a frequency (for example, every 10 m5ec) - Step 51 The ultrasonic waves sent out toward the road surface 29 are reflected by the road surface 29 and sent through the receiving horn 9 to the receiving microphone 7. and is applied to the amplifier circuit 15. Amplification circuit 15
amplifies the received reflected wave and outputs the amplified reflected wave to the voltage detection circuit 17, which receives a reflected wave intensity voltage. The reflected wave intensity voltage is input from the voltage detection circuit 17 to the control calculation device 21 through the A/D converter 19. As shown in FIG. 4, the voltage detection circuit 17 obtains a received pulse with a delay of t3 hours from the emission of the oscillation pulse, and after detecting the rising edge of this pulse, the voltage is 0.5n+.
The voltage at the time of scc is output as the reflected wave intensity (voltage value V) - Steps 52 and 53 In the control calculation unit 21, the calculation unit 25 compares the intensity V of the received pulse with the predetermined voltage values Vr+ and Vr2 - Stellar. Bu54~
57° Generally, the reflected wave intensity V shows large variations while the vehicle is running. In particular, as shown in Figure 5, the lowest value of the reflected wave intensity on an aging paved road with an uneven surface is due to reflections from compacted snow or frozen roads that have been compacted by vehicle traffic. Low friction coefficient with high wave strength (
μ) may be lower than the maximum value for the road, and if you try to determine the road surface condition by just transmitting and receiving ultrasonic waves twice, there is a possibility that false detection will occur between a rough paved road and a packed snow road. There is.

However, even on road surfaces where the reflected wave intensities are similar, when detecting the road surface condition at regular intervals and performing statistical processing of the reflected wave intensities, the reflected wave intensities of rough paved roads and compacted snow roads are different. The trends will be different. That is, it becomes as shown in the frequency cumulative diagram of FIG. 6 (voltage measurement results for the number of negative steps are integrated in order from the lowest voltage and expressed as a percentage curve).

■ Paved roads with high reflected wave intensity (concrete, etc.) ■
Paved roads with low reflected wave intensity (rough asphal roads, etc.), ■ Low 1 with high reflected wave intensity? Friction coefficient road (snow compacted road), ■
On each of the low friction coefficient roads (freshly snowed roads) where the reflected wave intensity is small, the cumulative value of the frequency of obtaining a reflected wave intensity voltage that is equal to or less than the fixed set voltage Vr+ or equal to or greater than Vr2 is statistically different. Therefore, two-wheel drive (2WD) is suitable for small paved roads ■ with reflected wave strength, and similar to this, four-wheel drive (4-wheel drive)
In order to separate the road from the low μ road (2) with a large reflected wave intensity that requires 4WD), the frequency cumulative value is set to 95% or more with respect to the comparison voltage value of the voltage intensity Vrl. Then, the number of times the comparison voltage value Vr+ is lower than or equal to the number of transmissions performed within a certain period of time is checked, and it is determined whether the count number/number of transmissions≧95%. In other words, when making a judgment every 128 times,
The number of times the voltage value is below Vr+ is (128x0.95==
=) If it is 122 times or more, it is determined that it is a low μ road.

Furthermore, in order to judge a high μ road, as is clear from FIG. 6, a region where the frequency cumulative value is low is used, and the case where the frequency cumulative value of intensity voltage Vr2 or less does not reach 30% is used as a reference. Therefore, if the number of times that the voltage value ■r2 becomes less than or equal to (128×0.30=) 38 times or less every 128 times, it is determined that there is a high μ road.

Therefore, when the reflected wave voltage intensity V becomes below the set voltage value Vr+, the performance device 25 increases the 4WD count by +1 count - step 54.55. Also, when the reflected wave voltage intensity V becomes below the set voltage value Vr2. 57.58 degrees, the 2WD count is increased by +1. The flow of steps 51 to 58 is repeated until the number of calls reaches a specified value, for example, 128 times. and,
When the number of calls reaches the specified 128 times, 4WD, 2
Step 5 in which the WD switching judgment is executed
8゜First, in order to determine whether it is necessary to switch to 4WD, it is determined whether the 4WD count is greater than the set number of times, that is, 122 or more (95% or more).
When this number of times is exceeded, it is assumed that the vehicle is traveling on a low μ road, and a command to switch to 4WD is issued. - Step 59.60゜When the 4WD count is low, whether it is necessary to switch to 2WD next. is judged. In other words,
When the 2WD count is less than a set number of times, for example 38, it is determined that the road is high and a command to switch to 2WD is issued - Steps 61 and 62. The routine is reset and a new Step 63 where the road surface condition detection flow is restarted: In this way, the voltage value of the reflected wave intensity is statistically processed, the road surface condition is grasped by determining the statistical characteristics, and the 4WD
- Automatic switching of 2WD is executed.

FIG. 8 shows another embodiment of the present invention, in which one transmitting microphone 3 and transmitting horn 5 are installed in the housing 1, and a plurality of receiving microphones 7 and receiving horns 9 are installed. It is. When multiple receiving means are provided in this way, if the distance between each receiving means is set to an appropriate value, multiple times the information from the road surface can be obtained within the same time, reflected wave intensity voltage value is obtained, and it is possible to shorten the time for statistical processing. Further, in each of the above embodiments, the transmitting and receiving means are shown as separate units, but it is also possible to use a plurality of integrated transmitting and receiving units, such as an ultrasonic sensor.

[Effects of the Invention] This invention compares the voltage value of the reflected wave intensity obtained by the receiving means with a predetermined setting value, and uses the frequency exceeding the comparison voltage value as discrimination information to determine the road surface condition. It has the advantage of being able to statistically understand road surface conditions and accurately detect road conditions.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to the claims of this invention, Fig. 2 is a circuit block diagram of an embodiment of this invention, Fig. 3 is a diagram of the electrical equipment configuration of the above embodiment, and Fig. 4 shows the operation of the above embodiment. A timing chart, FIG. 5 is a diagram showing temporal variations in the intensity of the three received waves, FIG. 6 is a frequency cumulative characteristic graph of the reflected wave intensity voltage of various road surfaces, FIG. 7 is a flowchart of the above embodiment,
FIG. 8 is an equipment configuration diagram of another embodiment of the present invention. 1... Housing 3... Transmitting microphone 5... Transmitting horn 7... Receiving microphone 9... Receiving horn 11... Transmitting/receiving circuit 13... Ultrasonic oscillator 15... Amplification Circuit 17... Voltage detection circuit 19.
...A/D converter 21...control calculation device 25...
Arithmetic device 27... Discrimination device patent applicant Nissan Motor Co., Ltd. Hoki 1 ≧ 2 fig. 3 fig. Haku 40 Gin Seki fig.

Claims (2)

[Claims] (1) A transmitting means for transmitting a detection wave toward the road surface at a constant cycle, a receiving means for receiving the reflected wave from the road surface, a means for detecting the intensity of the reflected wave from the receiving means, and a means for detecting the intensity of the reflected wave from the detecting means. A road surface condition detection device comprising a calculation means for comparing wave intensity with a set value and calculating a cumulative value of the frequency of exceeding the set value, and a determination means for determining a road surface condition from the output of the calculation means. (2) The road surface condition detection device according to claim 1, characterized by comprising a plurality of receiving means.