JP3223908B2 - Road surface condition estimation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road surface condition estimating device for estimating a road surface condition by irradiating a road surface with radio waves and measuring reflected waves from the road surface.

[0002]

2. Description of the Related Art This road surface condition estimating apparatus is also called a radio wave scatterometer, and is called dry, wet, water film, freezing, and snow based on the output intensity of scattering (output waveform) of a reflected wave from a road surface. The road surface condition in five stages is estimated.

FIG. 4 is a block diagram showing a configuration of such a conventional road surface condition estimation device. In the figure, an antenna 1 is installed at a high place near a road (general road, highway, etc.), transmits a pulse signal radio wave to the road surface of a road to be measured, and reflects the pulse signal from the road surface. To receive the waves. The antenna driving unit 2 drives the antenna 1 to a predetermined angle according to the antenna angle input data output from the data processing unit 6, and notifies the set angle when the antenna 1 has reached a predetermined angle. The set angle data is output to the data processing unit 6.

The transmitting / receiving section 3 generates a predetermined number of transmission pulse signals transmitted from the antenna 1 according to the control signal output from the data processing section 6 and outputs the generated signal to the antenna 1, and also outputs the predetermined number of transmission pulse signals to the antenna 1. It amplifies the number of received pulse signals and outputs the amplified signal to the AD converter 4. The A / D converter 4 converts the received pulse signal output from the transmission / reception unit 3 from an analog signal to a digital signal and outputs the digital signal to the pulse integrator 5. The pulse integrator 5 performs an integration process on the received pulse signals for the integration number according to the integration number input data output from the data processing unit 6 and outputs the integrated reception signal to the data processing unit 6. is there.

The data processing section 6 outputs antenna angle input data and integration number input data for controlling the operation of the antenna driving section 2 and the pulse integrator 5 to the antenna driving section 2 and the pulse integrator 5, respectively. Further, the data processing unit 6 outputs a control signal for instructing the transmission of the pulse signal a predetermined number of times to the transmission / reception unit 3. Further, the data processing unit 6 stores the reception signal output from the pulse integrator 5 and the antenna setting angle data output from the antenna driving unit 2 and, based on the stored data, calculates the road surface condition of the measurement range. Perform estimation processing.

The road surface condition result output unit 7 includes a data processing unit 6
The result of the estimated road surface condition is output by screen display or printout.

Next, the operation will be described. Prior to the start of the measurement, the operator inputs the area (range) of the road surface to be measured to the data processing unit 6 as the antenna scanning angle, and inputs the number of transmission pulse signals emitted from the antenna 1 to the data processing unit 6. The number of pulses of the transmission pulse signal is input when the road surface is measured by a single irradiation (hit) of the transmission pulse signal. In some cases, the road surface condition cannot be accurately estimated due to fluctuation or noise. This is because it is necessary to irradiate the same portion with the transmission pulse signal a plurality of times and take the average value of the reception signal.

The data processing unit 6 calculates the first set angle of the antenna 1 from the antenna scan angle input by the operator, and outputs the calculated set angle to the antenna drive unit 2 as antenna angle input data. In addition, the data processing unit 6 outputs the number of pulses of the transmission pulse signal input by the operator to the pulse integrator 5 as integration number input data. As described above, the number of pulses of the transmission pulse signal corresponds to the number of integrations of the reception pulse signal.

The antenna driving unit 2 drives the antenna 1 to a set angle in accordance with the antenna angle input data, and when the antenna 1 is set to a predetermined angle, processes the antenna set angle data for notifying the completion of the angle setting. Output to the unit 6. When the data processing unit 6 receives the antenna setting angle data output from the antenna driving unit 2, the data processing unit 6 outputs a control signal for instructing the transmission of a predetermined number of transmission pulse signals input by the operator to the transmission / reception unit 3.

When the control signal from the data processing unit 6 is input to the transmission / reception unit 3, a predetermined number of transmission pulse signals are generated in accordance with the control signal. The antenna 1 transmits (irradiates) the radio wave of the predetermined number of transmission pulse signals to the road surface, receives the reflection wave of the predetermined number of reception pulse signals from the road surface, and outputs the reflected wave to the transmission / reception unit 3. The transmitting / receiving unit 3 amplifies the predetermined number of received pulse signals and outputs the amplified signal to the AD converter 4.
The A / D converter 4 converts the received pulse signal from an analog signal to a digital signal and outputs the signal to the pulse integrator 5.

The pulse integrator 5 performs a predetermined number of integration processes on the received pulse signal in accordance with the integration number input data to obtain a smoothed received signal, and outputs the received signal to the data processing unit 6. The data processing unit 6 includes the pulse integrator 5
When the received signal output from the device is input, the received signal and the antenna setting angle data are stored as a set of data.

The above series of processing is automatically repeated while changing the set angle of the antenna 1 at predetermined intervals within the measurement range of the antenna scanning angle input by the operator. When all data collection (received signal and antenna setting angle data) within the measurement range of the antenna scanning angle is completed, the data processing unit 6 estimates the road surface condition using the stored data. The road surface condition result output unit 7 outputs a result of the road surface condition estimated by the data processing unit 6 by screen display or printout.

[0013]

However, in the above-described conventional road surface condition estimating apparatus, as shown in FIG. 5, when there is an obstacle such as a vehicle passing on the road surface in the measurement range, the obstacle is not affected. A reflected wave (unwanted signal) from an object is also measured (detected) as a received signal. As a result, there is a problem that the output intensity of the scattering (output waveform) of the reflected wave changes and the accuracy of the estimation result of the road surface condition deteriorates.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a road condition estimating apparatus capable of obtaining an accurate road condition estimation result even when an obstacle exists on the road surface. The purpose is to obtain.

[0015]

According to a first aspect of the present invention, there is provided a road surface condition estimating apparatus comprising: a time difference between a transmission time and a reception time of a radio wave theoretically determined from a distance between a radio wave transmission position and a road surface; The time difference between the transmission time and the reception time of the measured radio wave is compared, and if the two time differences do not match, the radio wave is removed from the measurement target and the road surface condition is estimated.

According to a second aspect of the present invention, there is provided a road surface condition estimating apparatus, comprising: a theoretical time difference determining means for theoretically determining a time difference between a transmission time and a reception time of a radio wave based on a distance between a radio wave transmission position and a road surface; Actual time difference calculation means for actually measuring the time and the reception time and calculating the time difference, and a comparison for comparing whether the time difference determined by the theoretical time difference determination means and the time difference calculated by the actually measured time difference calculation means match. And a removal processing means for removing the radio wave from the measurement target when the two time differences do not match.

According to a third aspect of the present invention, in the road surface condition estimating apparatus, the theoretical time difference determining means is configured to determine a time difference between the transmission time and the reception time of the radio wave according to the transmission angle of the radio wave.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a block diagram showing a configuration of a road surface condition estimation device according to Embodiment 1 of the present invention. In FIG. 1, an antenna 1 transmits a radio wave of a pulse signal to a road surface to be measured and receives a reflected wave of the pulse signal from the road surface. The antenna driving unit (theoretical time difference determining means) 2 drives the antenna 1 to a predetermined angle in accordance with the antenna angle input data output from the data processing unit 6, and when the antenna 1 has reached the predetermined angle, The antenna setting angle data (radio wave transmission angle) for notifying the setting angle is output to the data processing unit 6 and the memory 8.

The transmission / reception section 3 generates a predetermined number of transmission pulse signals transmitted from the antenna 1 in accordance with the control signal output from the data processing section 6 and outputs the signal to the antenna 1 and the delay time calculation processing section 9. Amplify a predetermined number of reception pulse signals received by the antenna 1 to A
-Output to the D converter 4 and the delay time calculation processing unit 9.

The A / D converter 4 converts a received pulse signal output from the transmission / reception unit 3 from an analog signal to a digital signal and outputs the digital signal to the pulse integrator 5. According to the integration number input data output from the processing unit 6, the integration processing of the reception pulse signals for the integration number is performed, and the integrated reception signal is output to the unnecessary signal removal processing unit 11.

The data processor 6 outputs antenna angle input data and integration number input data for controlling the operation of the antenna driver 2 and the pulse integrator 5 to the antenna driver 2 and the pulse integrator 5, respectively. Further, the data processing unit 6 outputs a control signal for instructing the transmission of the pulse signal a predetermined number of times to the transmission / reception unit 3. Further, the data processing unit 6 stores the reception signal output from the pulse integrator 5 through the unnecessary signal removal processing unit 11 and the antenna setting angle data output from the antenna driving unit 2, and stores the stored data. The estimation processing of the road surface condition in the measurement range is performed based on

The road surface condition result output unit 7 includes a data processing unit 6
The result of the estimated road surface condition is output by screen display or printout.

The memory (theoretical time difference determining means) 8 stores the transmission time of the transmission pulse signal and the road surface, which are theoretically determined according to the antenna setting angle data (radio wave transmission angle) output from the antenna driving unit 2. Time difference from the reception time of the received pulse signal reflected from the
Is stored in advance. The delay time calculation processing unit 9 calculates a time difference between the actually measured transmission time of the transmission pulse signal and the reception time of the reception pulse signal (hereinafter, actually measured time difference Δtm).

The comparator 10 compares the theoretical time difference Δts stored in the memory 8 with the actually measured time difference Δtm calculated by the delay time calculation processing section 9 and outputs an unnecessary signal removal identification signal according to the comparison result. This is output to the removal processing unit 11. The unnecessary signal removal processing unit 11 controls the passage of the received signal from the pulse integrator 5 to the data processing unit 6 according to the unnecessary signal removal identification signal output from the comparator 10.

Next, the operation will be described. Before starting the road surface measurement, the operator inputs an area (range) of the road surface to be measured as an antenna scanning angle to the data processing unit 6 as in the above-described conventional technology, and performs data processing on the number of pulses of the transmission pulse signal emitted from the antenna 1. Input to section 6.
The data processing unit 6 calculates the first set angle of the antenna 1 from the antenna scan angle input by the operator, and outputs the calculated set angle to the antenna drive unit 2 as antenna angle input data. In addition, the data processing unit 6 outputs the number of pulses of the transmission pulse signal input by the operator to the pulse integrator 5 as integration number input data.

The antenna driving unit 2 drives the antenna 1 to a set angle in accordance with the antenna angle input data, and when the antenna 1 is set to a predetermined angle, processes the antenna set angle data for notifying the completion of the angle setting. Output to the unit 6 and the memory 8.

When the data processing unit 6 receives the antenna setting angle data output from the antenna driving unit 2, the data processing unit 6 outputs a control signal for instructing transmission of a predetermined number of transmission pulse signals to the transmission / reception unit 3. On the other hand, the memory 8 stores a theoretical time difference Δts corresponding to the antenna setting angle data output from the antenna driving unit 2. This theoretical time difference Δt
s is theoretically determined by the distance between the antenna (radio wave transmission position) 1 and the road surface and the speed of the radio wave (the speed of light), but the speed of the radio wave and the installation height of the antenna 1 are known in advance. Therefore, the set angle (radio wave transmission angle) of the antenna 1 can be automatically determined as a parameter.

Upon receiving the control signal from the data processing unit 6, the transmitting / receiving unit 3 generates a predetermined number of transmission pulse signals in accordance with the control signal and outputs it to the antenna 1 (at the same time). The signal is output to the delay time calculation processing section 9. The delay time calculation processing unit 9 stores the time at which the transmission pulse signal output from the transmission / reception unit 3 is input as the transmission time of the transmission pulse signal.

The antenna 1 transmits (irradiates) the radio wave of the transmission pulse signal a predetermined number of times to the road surface, and receives the reflected wave of the reception pulse signal of the predetermined number of times reflected from the road surface or an obstacle such as a vehicle (see FIG. 5). And outputs it to the transmitting / receiving section 3. The transmitting and receiving unit 3 amplifies the predetermined number of received pulse signals and
It outputs to the D converter 4 and the delay time calculation processing section 9.

The A / D converter 4 converts the received pulse signal from an analog signal to a digital signal and converts the analog signal into a digital signal.
In accordance with the integration count input data, the pulse integrator 5 performs a predetermined number of integration processes on the received pulse signal to obtain a smoothed reception signal, and outputs the received signal to the data processing unit 6.

On the other hand, the delay time calculation processing section 9 calculates an actually measured time difference Δtm from the actually measured transmission time of the transmission pulse signal and the reception time of the reception pulse signal, and outputs the difference to the comparator 10.

The comparator 10 compares the theoretical time difference Δts stored in the memory 8 with the actually measured time difference Δtm calculated by the delay time calculation processing section 9 and determines whether the received signal is an unnecessary signal (a reflected wave from an obstacle). It is determined whether or not there is. FIG. 2 is a flowchart for explaining such comparison determination processing of unnecessary signals by the comparator 10. Upon receiving the theoretical time difference Δts and the measured time difference Δtm, respectively (steps ST1 and ST2), the comparator 10 determines whether the theoretical time difference Δts matches the measured time difference Δtm (whether or not they are the same) (step ST3). ).

Here, when the reflected wave from the ground surface (road surface) and the reflected wave from the obstacle are compared, as shown in FIG. 3, in the case of the reflected wave from the ground surface, the measured time difference Δtm is equal to the theoretical time difference Δts. In the case of a reflected wave from an obstacle, the time at which the reflected wave arrives is increased by the amount of the obstacle (the round-trip path between the antenna 1 and the obstacle is shortened) (see FIG. 5), and the measured time difference Δtm is shorter than the theoretical time difference Δts. Therefore, in the case of a reflected wave from an obstacle,
The theoretical time difference Δts does not match the actually measured time difference Δtm.

If the result of the above determination of the theoretical time difference Δts and the measured time difference Δtm shows that the theoretical time difference Δts and the measured time difference Δtm do not match, the comparator 10 determines that the reflected wave is a reflected wave from an obstacle, and turns on the flag. Is output to the unnecessary signal removal processing unit 11 as an unnecessary signal removal identification signal (step ST4). On the other hand, the theoretical time difference Δts and the measured time difference Δt
If m coincides with each other, it is determined that the signal is a reflected wave from the ground surface (road surface), and the off flag is output to the unnecessary signal removal processing unit 11 as an unnecessary signal removal identification signal (step ST).
5).

When the comparator 10 compares the coincidence between the theoretical time difference Δts and the measured time difference Δtm, strictly speaking, even if the reflected wave from the road surface, the two time differences may not coincide due to an error or the like. The comparison is made in consideration of an error, for example, by truncating the number of digits after the decimal point between the two time differences.

When the unnecessary signal removal identification signal output from the comparator 10 is an on-flag, the unnecessary signal removal processing section 11 sets the gate to an on state and sets the pulse integrator 5 Are not output to the data processing unit 6 (discarded). vice versa,
When the unnecessary signal elimination identification signal output from the comparator 10 is the off flag, the unnecessary signal elimination processing unit 11 sets the gate to the off state and sends the received signal output from the pulse integrator 5 to the data processing unit 6 as it is. Output.

The data processing unit 6 includes an unnecessary signal removal processing unit 1
When a reception signal output from the pulse integrator 5 is input after passing through 1, the reception signal and antenna setting angle data are stored as a set of data. Then, the road surface condition estimating apparatus automatically repeats the above series of processes while changing the set angle of the antenna 1 at predetermined intervals within the measurement range of the antenna scanning angle input by the operator.

When all data collection (receiving signal and antenna setting angle data) within the antenna scanning angle measurement range is completed, the data processing unit 6 estimates the road surface condition using the stored data. The road surface condition result output unit 7 outputs a result of the road surface condition estimated by the data processing unit 6 by screen display or printout.

As described above, according to the first embodiment, whether the received signal is an unnecessary signal is determined by comparing the theoretical time difference Δts and the actually measured time difference Δtm, and the unnecessary signal is removed. With such a configuration, even when an obstacle is present on the road surface, the road surface condition can be estimated only by the reflected waves from the road surface, and as a result, an accurate road surface condition estimation result can be obtained.

Further, by determining the logical time difference Δts in accordance with the set angle of the antenna 1, the theoretical time difference Δts at each measurement point on the road surface within the measurement range can be immediately determined.

[0041]

As described above, according to the first aspect of the present invention, the time difference between the transmission time and the reception time of the radio wave theoretically determined from the distance between the radio wave transmission position and the road surface is measured. The time difference between the transmission time and the reception time of the received radio wave is compared, and if the two time differences do not match, the radio wave is removed from the measurement target to estimate the road surface condition,
Even when an obstacle is present on the road surface, the road surface condition can be estimated only by the radio waves reflected from the road surface, and as a result, an accurate road surface condition estimation result can be obtained.

According to the second aspect of the present invention, the theoretical time difference determining means for theoretically determining the time difference between the transmission time and the reception time of the radio wave from the distance between the radio wave transmission position and the road surface, the transmission time and the reception time of the radio wave Actual time difference calculating means for actually measuring and calculating the time difference, and comparing means for comparing whether or not the time difference determined by the theoretical time difference determining means and the time difference calculated by the actually measured time difference calculating means match. If the time difference does not match, the apparatus is provided with a removal processing means for removing the radio wave from the object to be measured, so that even if there is an obstacle on the road surface, the radio wave reflected from the road surface is provided in the same manner as in the first aspect of the invention. Alone, the road surface condition can be estimated, and as a result, an accurate road surface condition estimation result can be obtained.

According to the third aspect of the present invention, the theoretical time difference determining means is configured to determine the time difference between the transmission time and the reception time of the radio wave according to the transmission angle of the radio wave. This has the effect that the theoretical time difference in points can be determined immediately.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a road surface condition estimation device according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating a process of comparing and determining unnecessary signals by a comparator.

FIG. 3 is a diagram comparing a measured time difference of a reflected wave from an obstacle and a measured time difference of a reflected wave from a road surface;

FIG. 4 is a block diagram showing a configuration of a conventional road surface condition estimation device.

FIG. 5 is a diagram illustrating reflection of radio waves when an obstacle is present on a road surface.

[Explanation of symbols]

 2 Antenna driver (theoretical time difference determining means) 8 Memory (theoretical time difference determining means) 9 Delay time calculation processing section (actually measured time difference calculating means) 10 Comparator (comparing means) 11 Unwanted signal removal processing section (removal processing means)

──────────────────────────────────────────────────続 き Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01W 1/00 G01N 22/00 G01S 13/04

Claims (3)

(57) [Claims] 1. A road surface condition estimating device for transmitting a radio wave to a road surface, receiving a radio wave reflected from the road surface, and estimating a road surface condition by measuring the intensity of the received radio wave, comprising: The time difference between the transmission time and the reception time of the radio wave theoretically determined from the distance to the road surface is compared with the time difference between the transmission time and the reception time of the radio wave actually measured, and the two time differences do not match. In such a case, the road condition estimating apparatus is configured to estimate the road condition by removing the radio wave from the measurement target. 2. A road surface condition estimating apparatus for transmitting a radio wave to a road surface, receiving a radio wave reflected from the road surface, and estimating a road surface condition by measuring the intensity of the received radio wave, comprising: Theoretical time difference determining means for theoretically determining the time difference between the transmission time and the reception time of the radio wave from the distance to the road surface; and an actual measurement time difference calculation for actually measuring the transmission time and the reception time of the radio wave and calculating the time difference. Means, comparing means for comparing whether the time difference determined by the theoretical time difference determining means and the time difference calculated by the actually measured time difference calculating means match, and if the two time differences do not match, measure the radio wave. A road surface condition estimating device comprising: a removal processing unit that removes the road surface from an object. 3. The road surface condition estimating device according to claim 1, wherein the theoretical time difference determining means determines a time difference between a transmission time and a reception time of the radio wave according to a transmission angle of the radio wave. .