development of rainfall information manufacturing...

Development of Rainfall Information Manufacturing

Technology by Using Signal of a Vehicle Rainfall Sensor

Byung-Sik Kim1, Young-Gon Kim2, Suk-Ho Lee3,

1 Department of Urban & Environmental Disaster Prevention School of Disaster Prevention,

Kangwon National University, 346 Joogang-ro, Smacheok-si, Gangwon-do, Republic of Korea

Abstract. This study is to develop rainfall information manufacturing

technology by using a rain sensor placed on a vehicle to carry out an automatic

wiping function. The rainfall information manufacturing method is using the

sensitivity of transmit-reception of a light sensor. When raindrop forms on a

window shield, this can make received light signal scattered and cause it

decreased. At this moment, the bigger raindrop is, the less reception receives

and rainfall information can be earned by using this reception. The reception

data of sensor is collected up to 250times per second, 8channels in total. The

collected rainfall data is developed by using the relationship of Signal and

Rainfall: S-R relationship, eliminating initial value after analyzing average

value from 1 to 10 minutes intervals to have rainfall information as a

representative big data.

Keywords: Rain Sensor, Rainfall Information, S-R Relationship, Big Data

1 Introduction

Most of vehicles have produced recently have automatic wiping function controlling

the speed of wipers according to rainfall amount. The automatic wiping function is to

control speed of the wipers according to the size of raindrop on detection area of

sensor by using rainfall sensor on a vehicle. In this study the existing rainfall sensor

was developed to have rainfall information by using the size of raindrops than the

automatic wiping function itself. The upgraded rainfall sensor is using sensing signal

from optic acquisition and this sensing signal is the light signal of sender reflected off

windshield so it is converting the degree of decreased light signal of optic acquisition

scattered by raindrop to rainfall information. The rainfall manufacturing method by

1 Professor(1st author), Department of Urban and Environmental Disaster Prevention

Engineering, Kangwon National University, Gangwon-do, Republic of Korea; E-mail:

[email protected] 2 Master Course, Department of Urban and Environmental Disaster Prevention Engineering,

Kangwon National University, Gangwon-do, Republic of Korea; E-mail:

[email protected] 3 Research professor(corresponding author), Department of Urban and Environmental Disaster

Prevention Engineering, Kangwon National University, Gangwon-do, Republic of Korea; E-

mail: [email protected]

Advanced Science and Technology Letters Vol.141 (GST 2016), pp.133-138

http://dx.doi.org/10.14257/astl.2016.141.27

ISSN: 2287-1233 ASTL Copyright © 2016 SERSC

using vehicle rainfall sensor is utilized then each vehicle on the road can be a rainfall

observatory, this can make high resolution rainfall measuring network and it can be

used to have various weather contents like road inundation information, detour

information etc. Therefore, in this study S-R relationship formula was developed by

using a rain sensor signal (S) and rain intensity (R) which can converted to rain

information by using signal from a rainfall sensor of a vehicle.

2 Theoretical Background

The rainfall measuring method by using rainfall sensor is to use reflexibility between

sender which can send light signal and receiver which can receive light signal from

front wind shield. When there is no rainfall, there is no raindrop, this can cause total

reflection, the light signal from sensor is reflected from front screen. Therefore, in this

case the light signal from sender comes back but when there is raindrop then raindrop

can cause scatter the light signal from sensor and decrease light signal. Therefore, if

the light signal relationship from receiver according to raindrops range in size can be

interpreted then the rainfall information manufacturing can be achieved.

Fig. 1. Operating Principle of Rain Sensor

3 Application and Result

3.1 Production of Rainfall

Rain sensors collect 250data per second from 8 channels in total. Supposing a rain

sensor of a vehicle as an observatory then 250 data per one observatory from 8

channels per second which means approximately 1.2million data can be produced in

10minutes. The rainfall information we want to have should be extracted from this big

amount of data. When wipers are working, wiper is collecting water drops from

Advanced Science and Technology Letters Vol.141 (GST 2016)

134 Copyright © 2016 SERSC

winshield and this causes decrease on signal value instantly. Therefore, among

1.2million data in 10minutes, the initial value and the instant numerical abnormality

should be eliminated to have proper rainfall information. But it is not possible to

eliminate numerical abnormality of millions of data one by one.

Fig. 2. The Initial Value and the Outlier Value of the Sensor Signal

3.2 Data Collecting Method

As stated earlier, eliminating numerical abnormality is almost impossible, the method

of including numerical abnormality was found rather than eliminating it. When we

use wipers with constant speed, this means this numerical abnormality can be

produced accordingly, data from rain sensor should be analyzed as 4ms, 1s, 2s, 5s,

10s, 30s, 60s, 120s, 300s. Refer data range 35 mm/hr to Fig 3 showing data range

according to time. After analyzing the value range by increasing average time under

same rain intensity, the data was collected approximately signal 550. Refer the test

result simulated at the range of 10~60 mm/hr as same method. The signal of rain

sensor from constant rain intensity can collect certain value by average. Therefore, the

rainfall intensity and signal average value during certain period of time is related to

linear approaches so S-R relationship formula by using sensor signal (S) and rain

intensity (R) can be produced.

(a) 4 ms (Original data) (b) 1 s


Copyright © 2016 SERSC 135

(c) 2 s (d) 5 s

(d) 10 s (e) 30 s

(e) 60 s (f) 120 s

(g) 300 s (h) 600 s

Fig. 3. Average Sensor Signal over Time Interval(35mm/hr)

3.3. Development of S-R Relationship Formula

A 10~60mm of rainfall was generated by using rainfall generator to develop S-R

relationship formula. Rain sensor data during 1 hour at each rain intensity was

collected. Refer analysis flow chart to Fig. 4.



Fig. 4. Rainfall Analysis Flow Chart

Collected data is to do regression analysis by using in units of 1, 2, 5 and 10

minutes except initial value. The sensor-rainfall relation was set to 80% of error range

considering the degree of a radar rainfall measuring data around 80%. As a result,

when the relation formula is set by using the average 5minutes data then we can

achieve appropriate result in target range (Fig. 5).

(a) 1 min (b) 2 min

(c) 5 min (d) 10 min

Fig. 5. Signal(S)-Rainfall(R) relationship


Copyright © 2016 SERSC 137

Therefore, the following relation formula is used then the rainfall information of

5minutes interval by using rainfall sensor can be calculated.

R = - 0.475S + 265.62(R2=0.8252). (1)

4 Conclusion

In this study, the actual rainfall amount is to measure by revising the existing wiper

moving rain sensor and using properly developed rainfall measuring sensor. The

artificial rainfall with fixed rainfall intensity was generated through a indoor test to

convert a signal of rain sensor to rainfall amount and the relation formula between

sensor-rainfall amount was developed by analyzing the relationship between rainfall

amount and a signal of sensor. It is estimated that the developed formula by using

outdoor test result can be adjusted to actual value of rainfall through revision. Also if

a technology converting collecting data to rainfall amount through moving vehicle

is used by revising data collection and analyzing method then spatiotemporal high

resolution rainfall information can be generated.

Acknowledgments. This research was carried out with the support of Korea

Meteorological Industry Promotion Agency (KMIPA 2015-4030)

References

1. Chandrasekar, V., Wang, Y., Chen, H.: The CASA quantitative precipitation estimation

system: a five-year validation stud. Hazards Earth Syst. VOL. 12, pp. 2811-2820(2012)

2. Haberlandt, U., Sester, M.: Areal rainfall estimation using moving cars as rain gauges a

modelling study. Hydrol. Earth Syst, VOL, 14, pp. 1139-2010(2010)

3. Kim, B.S., Kim, H.S., Yang, D.M.: Comparison of Spatial Distributions of Rainfall

Derived from Rain Gages and a Radar. Koren Wetlands Society, VoL. 12, No.3, pp. 63-

73(2010)



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