SMART ACTIVE LIQUID LEVEL MEASUREMENT USING INFRARED ... · (1) development of IR sensor arrangement (2) Transfer function determination (output voltage of IR receiver v/s distance)

International Journal of Research in Engineering, Technology and Science, Volume

VII, Special Issue, Feb 2017

www.ijrets.com, [email protected], ISSN 2454-1915

P. Veenasheela Rao and Dr. S B Chaudhury 1

SMART ACTIVE LIQUID LEVEL MEASUREMENT USING

INFRARED SENSORS SUITABLE AS COSUMER PRODUCTS

P. Veenasheela Rao1, Dr. S B Chaudhury2

1Lecturer, Department of Electronics and Communication Engineering,

2Head of Department, Department of Electronics and Communication Engineering, Al-Kabir Polytechnic

College, Jamshedpur, Jharkhand, India

ABSTRACT:

The infrared (IR) transceiver sensors are widely used in industries, medical equipment, and commercial applications as critical or non-critical proximity sensor. The amplitude response of IR sensors based on reflected ray from an object is non-linear and depends on the reflectance characteristics of the surface of the object. Hence, the use of IR sensor output in its original analog form has not been researched much for industrial applications. However, fast response of IR sensor is attractive for enhancing it’s applicability in analog form. This paper explores an approach, to use the reflected IR light intensity in its original analog form to estimate the distance of the reflecting object. This work is based on the “Phong Illumination Model” for determining the distance of reflecting object having the knowledge of properties of a surface. For simplifying the calculation, the IR (transmitter and reflector) sensor is computed as normal to the surface. The proof of concept

is demonstrated by measuring the water level of tank

Keywords: IR sensor, distance measurement, level sensor, microcontroller, industrial

measurement

[1] INTRODUCTION

The Infrared Sensor i.e. combination of Infrared emitter (IR LED) and Infrared photo-transistor are

widely used for numerous applications as proximity sensors e.g. commonly used as obstacle detector

[1]. As the proximity sensor their output is used in digital form (high & low logic) by using a

comparator at the output of IR photo-transistor/diode. The amplitude response of infrared (IR)

sensors depends on the reflectance properties of the target [2, 3]. Due to this the reflected light

intensity from IR sensor, in its original analog, has not gained popularity as sensor for commercial

product. Therefore, in order to use IR sensor for using as analog sensing information accurately,

prior knowledge of the surface must be known. In such case, the processing of analog information

also becomes complicated. These may be few reasons of non-utilization of IR transceiver as analog

sensor. Literature survey reveals that, very few researchers have explored IR sensors using reflected

light intensity to estimate the distance of an object. However, low cost of the IR sensor and their

inherently fast response are going to be pivotal for the use in various commercial applications as

distance measurement, level sensing, and object position detection etc. in future. Keeping in mind,

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SMART ACTIVE LIQUID LEVEL MEASUREMENT USING INFRARED SENSORS SUITABLE

AS COSUMER PRODUCTS


the future prospective of IR sensors utilization as analog sensing device, in this work we have

tried to explore the possibility of using the IR (analog) sensor as continuous water level

measurement in tank. Commercially different level sensors are available for different applications

[4]. Just to name few are: Calibrated pitot tubes, Ultrasonics (Using Doppler effect - a Tx/Rx pair

straddling the pipe), Thermal methods (if the liquid has well known c and k then a hot-wire

'anemometer' would sufficient), Piezoelectric (vortex/swirl meters - flow creates a stable pattern that

exerts pressure against piezo elements, Electrodynamic (If the liquid is conductive, then passing a

current through it in the presence of a magnetic field will yield a detectable voltage) etc.

In this work, we focused on the suitability of the proposed sensors to detect and active measurement

of the non-turbulent water level. The basic experiments indicate that the low cost IR sensors are able

to give reliable water level measurement. Thus, this new sensor can be used commercially. As a

future work, further development work is in progress to integrate the sensor output with low cost

ARM 16 bit processor which can be fitted in any water tank and can be commercialized with

affordable cost for the consumer market.

[2] PROBLEM DESCRIPTION

The backbone of the complete measurement concept is based on the infrared light intensity back-

scattered from water level. The calculations are carried out as described by “Phong Illumination

Model” which correlates the surface property, angle of incident IR light, intensity of reflected light

[2]. A simplified expression is proposed for modeling the sensor response as a function of distance

and angle of incidence. Using Phong Model, Tarek Mohammad calculated the distance to an object

with a flat surface [2] which is:

𝑑 = 𝑟(cos(ø) − 1) + cos(ø) √𝐶0 𝑐𝑜𝑠(ø)+𝐶1 cos (2ø)

𝐸 --------------- (1)

Where r = radius of sensor,

ø = angle between the source and normal of the surface,

C0, C1 = constants of Phong Model,

E = energy absorbed by the sensor.

In our study, the object is the upper surface layer of water in water tank as shown in Figure 1.

Equation 1 can be applied for the water level analysis of the present case.

Figure 1 Schematic Diagram of water Tank





For simplifying the calculation, the IR (transmitter and reflector) sensor is computed as normal to

the surface. Hence ø = 0° (ideally). Since we have observed the experiment for the non-turbulent

water, the water surface can be assumed as flat surface. Implementing ø ≤ 20° into the eqn.1

provides the water level as:

𝑑 √𝐶0+𝐶1

𝐸 --------------- (2)

Equation 2 reveals that water level is inversely proportional to √𝐸. For lower energy absorption

by the sensor (in the case of lower water level), the distance between the water surface and sensor

is higher. The energy (E) absorbed by the phototransistor is:

𝐸 = 𝐼𝐴

(2𝑑)2 --------------- (3)

Where, I = intensity of the sensor,

A = area of the sensor,

2d = distance travelled by the IR ray in transmitting and receiving by the sensor

(assuming that transmitter and receiver are separated with a negligible distance, since ø = 0°.

The typical characteristic of IR receiver is shown in Figure 2. It can be observed that the

sensitivity of sensor depends upon the angle of reflection (or angle of incident of IR transmitter)

and it is maximum when it is normal to the water surface [5]. In practical purpose it is not possible

and tried to keep as minimum as possible (ø ≤ 20°). However, the angular position of the IR sensor

is computed as normal to the surface for simplifying the calculation. The presented approach uses

only one parameter i.e. the reflection coefficient, αi. This approach gives satisfactory results for

water level. The influence of uncertainty of the relative reflectivity coefficient (α i) has been

analyzed [6], and an expression has been found to give a rough estimate of the error produced in

the distance estimation.

Figure 2 Typical characteristic of IR receiver




AS COSUMER PRODUCTS


[3] SYSTEM DESCRIPTION

Harry D. Downing and Dudley Williams (1975) had determined quantatively the optical properties

of water in the Infrared [7]. The paper presented that remarkable variations had been appeared in

the dielectric constant and the Lambert absorption coefficient due to the effect of Infrared rays in

water. This proved that the water surface measurements can be achieved using IR Sensors.

Figure 3 Phong Model

According to the Phong Illumination Model as shown in Figure 3, light is reflected in a number of

directions for one particular angle of incidence (i). But it is most intense in the direction where i =

r. In the present case, i = ø ≤ 20°. The intensity drops off to zero on either side of the angle r.

Figure 4 Block schematic representation of the

proposed scheme

Figure 5 Arrangement diagram of sensor

housing with electronics and mounting

arrangement

The block diagram of the system is shown in Figure 4. The implementation of proposed system

mainly involves four steps, which are:

(1) development of IR sensor arrangement

(2) Transfer function determination (output voltage of IR receiver v/s distance)

(3) design of signal processing and interfacing with microcontroller and

(4) Software development.

Arrangement diagram of sensor housing with electronics and mounting arrangement is shown in

Figure 5. This is smart active liquid level measurement which will be suitable as consumer

products.





[4] LAB SETUP

A 3mm IR Tx-Rx pair is used for measuring water level and it is connected to 5V DC power supply

[8]. The anolog output is directly measured in multimeter. We used a ruler scale to obtain the actual

value of water level. The different views of complete lab setup are shown in Figure 6. The receiver

(photodiode) detects the light intensity reflected by water surface. We have to find out the limitation

of range that can be measured precisely. Accurate measurement needs software implementation in

microcontroller as per Figure 4. The readings have been analyzed between 5.5cm (lower level) to

21.5cm (higher level). It has been observed that water level below 12cm the output values don’t

have much difference. For higher water levels the graph shows better results. The upper level is

restricted due to the size of water tank. It can be extended to much higher level by choosing bigger

water tank. The final observation has been presented in the observation table and respective graph

has been drawn.

Figure 6 Conceptual arrangement for IR Sensor mounting




AS COSUMER PRODUCTS


[5] OBSERVATION TABLE

S. No. Liquid Level (cm)

Output Voltage (mV)

1 21.5 22.9

2 21.0 22.2

3 20.5 20.1

4 20.0 19.4

5 19.5 18.5

6 19.0 17.6

7 18.5 17.0

8 18.0 16.5

9 17.5 16.1

10 17.0 15.8

11 16.5 15.6

12 16.0 15.4

13 15.5 15.1

14 15.0 15.0

15 14.5 15.0

16 14.0 14.8

17 13.5 14.7

S.

No. Liquid Level (cm)

Output Voltage

(mV)

18 13.0 14.7

19 12.5 14.6

20 12.0 14.5

21 11.5 14.5

22 11.0 14.5

23 10.5 14.5

24 10.0 14.4

25 9.5 14.4

26 9.0 14.4

27 8.5 14.4

28 8.0 14.4

29 7.5 14.3

30 7.0 14.3

31 6.5 14.3

32 6.0 14.2

33 5.5 14.2

Figure 7 Experimental result

[6] RESULT AND CONCLUSION

In this work, we focused on the ability of the sensors to detect the level of water surface in the tank.

The experimental results obtained are depicted in the [Figure 7]. The results show good agreement

between the expected level and the real data obtained during the tests. Work is still in progress to

Ou

tpu

t V

olt

age

(mV

) --

----

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have a linear change in output with respect to change in input. The experiment proves the validity

of Phong Illumination model which is quite helpful in the measurement of water level.

FUTURE SCOPE

The proposed future works are three fold:

1) To incorporate different signal processing to have proper level measurement even during

water level turbulence during tank filling.

2) It is proposed to incorporate different algorithm related water discharge rate computation,

tank filling rate computation.

3) And making the complete system as Internet of Things (IoT) enabled so that individual water

consumer can have complete transparency about the water level, water consumption pattern

in their mobile.

ACKNOWLEDGEMENT

We wish to acknowledge our debt to Al-Kabir Polytechnic, Kopali, Jamshedpur for providing us

the platform to complete our project. We express our sincere gratitude to all members of our

department and to generous support by the management of our college.

REFERENCES

[1] Technical Information SD-12, “Characteristics and use of infrared detectors” HAMAMATSU,

SOLID STATE DIVISION, pg. 3-7.

[2] Tarek Mohammad, “Using Ultrasonic and Infrared Sensors for Distance Measurement”. In the

International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing

Engineering Vol: 3, No: 3, 2009.

[3] G. Benet, F. Blanes, J. E. Simo, P. Perez, “Using Infrared sensors for distance measurement in

mobile robots”, Robotics and Autonomous Systems 1006 (2002) pg. 1-12.

[4] A. K. Sawhney, Puneet Sawhney, “Mechanical Measurements and Instrumentation & Control”,

Dhanpat Rai & Co. (P) Ltd., pg. 837-850.

[5] Data Sheet of IR Light-to-Voltage Optical Sensors, Texas Instruments, SOES008A-December

1992-Revised Februry 1993.

[6] G. Benet, F. Blanes, J. E. Simo, P. Perez, “Using Infrared sensors for distance measurement in

mobile robots”, Robotics and Autonomous Systems 1006 (2002) pg. 1-12.

[7] Harry D. Downing and Dudley Williams, “Optical Constants of Water in the Infrared”. In the

Journal of Geophysical Research, Vol.80, No. 12, pg. 1656-1661.

[8] “How to make IR Sensor Modules using comparator”, from Google Search.



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SMART ACTIVE LIQUID LEVEL MEASUREMENT USING INFRARED ... · (1) development of IR sensor arrangement (2) Transfer function determination (output voltage of IR receiver v/s distance)