Design of an automatic irrigation control system
-
Upload
oyediran-tobiloba -
Category
Engineering
-
view
197 -
download
17
Transcript of Design of an automatic irrigation control system
given by:
OYEDIRAN TOBILOBA JOSEPH
10CK011291
Electrical and Electronics Engineering
Friday 10th April, 2015
1. INTRODUCTION
2. AIM AND OBJECTIVES
3. METHODOLOGY
4. SYSTEM DESIGN
5. RECOMMENDATIONS
6. QUESTIONS AND ANSWERS
WHY THIS PROJECT ? ?
Humans always had to be involved. Someone has to be present, either continuously or intermittently. Such time could be used for something else!
A lot of water is wasted in the process as there is no way to ensure that the water actually get to the roots of the crops. There is not even enough water in the world for humans yet!
Design an irrigation system that can
autonomously control the irrigation process
and conserve water while at it.
• Develop a sensor to determine when irrigation is necessary
• Develop a control circuit (the brain of the system)
• Develop a pumping and delivery channel for the irrigation water
• Develop a power supply unit for the system
A moisture sensor was constructed to model the electrical resistance of the soil;
A regulated 12 volts power supply unit was constructed to power the system;
The control circuit was implemented using operational amplifier and timer;
And the pumping subsystem consisting of a submersible low-noise micro water pump was constructed using a small dc-operated motor.
Power Supply Unit
Step down transformer : turns ratio 16:1; 15V output
Diode bridge
Filtering capacitor : 2200uF
Voltage regulator: LM7812 ; 12V output
Noise cancelling capacitors : 0.1uF
Unit output 12V = control circuit supply voltage = pump’s driving voltage
Moisture sensing
Modelling soil electrical resistance
Inverse relationship between soil moisture content and electrical resistance
Calibration indicated 100kilo ohms as the sensor’s dry point for most soil samples.
Sharp sensitivity
Specs: probes’ length = 6cm
separating distance = 4cm
totally dry soil resistance = 1-2 mega ohms
The Control Circuit
15.0
8.0
2.5
5.0
3.0
1.5
12.0
7.5
2.0
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
40 50 60 70 80 90 100 110
Irrigationtime
(seconds)
Level of soil dryness (%)
Graph of irrigation time against percentage of soil dryness
clay soil
sandy soil
loamy soil
For the large scale implementation of this project:
a more powerful motor should be used;
the control circuit be implemented using amicrocontroller in order to accommodate morethan one sensor;
where homogenous irrigation is needed andthe crops cover every part of the area, the dripmeans of irrigation should be modified into asprinkling system
where there is possibility of presence of wateraround where the control box is located, themode of power supply should be implementedusing detachable, rechargeable batteries.