Declaration that this project is our original work

We are a 5th year Electrical and Computer Engineering students undersigned, declare that this project is our original work and has not been presented for a degree in any form and in any other university and that to the best of our knowledge and belief all source of material used for the project have been duly acknowledged.
Declared by:
Name Signature
1. __________________________________ _______________________
2. __________________________________ _______________________
3. __________________________________ _______________________
4. __________________________________ _______________________
5. __________________________________ _______________________
Date __________________
Approval of Advisor
As the student advisor, I clarify that this final year project which prepared by the students listed above is original work and complained according to the guideline provided by the department as far as my knowledge is concerned.

Confirmed by Advisor:
Name _____________________________________
Signature __________________________________
Date ______________________________________
Place: Jimma.

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First of all, we would like to thank the almighty God for the base of all the successful progress of life as a whole and this project as a particular. We would like to offer our deepest gratitude to our advisor Dr. Amruzh who shared with us the main principles of a successful preparation for a final project, who had the main role of providing us with the components of the project, and reviewing the context of this project with us. We extend our sincere thanks to Mr. Mengistu F. for his advice, support and guidance through the entire project.
Finally, we also extend our sincere thanks to all other faculty members of Electrical and Computer Engineering department and our friends for their support and encouragement.

With the increasing of Ethiopian population day to day the focus on effective and agricultural methods are getting more attention. To satisfy the need of those population we must develop and follow modern agricultural technology. Not only those but also, according to survey conducted by WHO (World Health Organization) it is estimated that every year about 3 million workers are affected by poisoning from pesticides from which 18000 die. In addition to these, there are many people that are suffering for venomous snakes and insects that can be occurred regularly in farm field. Thus with this as a major area of concern, this project deals with the development of remote controlled smart pesticide and fertilizer spraying hexacopter drone to help farmers. The proposed drone should be able to spray insecticides, pesticides and fertilizers using a tank provided onto the frame of the drone.
The process of spraying fertilizer, pesticide and manure spreading technique is done by using android application device. Here the hexacopter can be control through android phone for fertilizer and pesticide spraying process. So the hard work, human efforts, number of human labors can be reducing by it. This system reduce the problem related to the agricultural field and increase the agricultural productivity and also reduce the health problems which are caused by manual spraying.

Table of content
List of FiguresList of TablesAcronymsBLDC Brushless DC motor
CW Clockwise
CCW Counter Clockwise
DC Direct Current
ESC Electronic Speed Controller
FCB Flight Controller Board
GND Ground
IMU Inertial Measurement Unit
I2C Inter-Integrated Circuit
LiPo Lithium Polymer
PDB Power Distribution Board
PID Proportional Integral Derivational
PVC Poly Vinyl Chloride
PWM Pulse Width Modulation
RC Remote Control
RF Radio Frequency
RPM Revolution Per Minute
RPV Remotely Piloted Vehicle
SCL Serial Clock Line
SDA Serial Data Line
UAV Unmanned Arial Vehicle
WHO World Health Organization
WI-FI Wireless Fidelity
It is known that the main source of Ethiopian economy is agriculture. More than 80 percent of the population of the country are farmers whose income is depend on mainly agriculture. Even if so, today there are many people which are suffering for hunger due to shortage of food which is the result of traditional agricultural practice throughout the country. Now days the government of Ethiopia start to import agricultural products from foreign countries to solve this problem. However, this may not be the exact solution of the problem. As we know, the population of Ethiopia is increasing day to day. With the increasing of population day to day the focus on effective and modern agricultural methods are must get more attention, but it still uses obsolete methods.
The application of pesticides and fertilizers play a vital role for modernization of agricultural sector and gives higher crop yields. The rate of agriculture production is affected by major biological factors such as pests, diseases, weeds etc. These biological factors can be controlled by human beings with the help of pesticides and fertilizers, which ultimately increasing the productivity. All most all farmers in the country uses labor force to spray those pesticides and fertilizers to their farm in traditional way. Conventionally the spraying is done by labors carrying backpack sprayer and fertilizers are sprayed manually. During this time, pesticide exposure affects the human health in various ways and causes neurological and skin diseases like asthma, allergies, hypersensitivity, cancer, hormone disruption, and problems with reproduction and fatal development. According to survey conducted by WHO (World Health Organization) it is estimated that every year about 3 million workers are affected by poisoning from pesticides from which 18000 die. In addition to these, there are many people that are suffering for venomous snakes and insects that can be occurred regularly in farm field.

To overcome all these ill effects of the pesticides and fertilizers on human beings and also used to spray pesticides over large areas in short interval of time compared to conventional spraying, we are going to design and implement an automated aerial pesticide sprayer, so as to increase crop productivity throughout the country.

The hexacopter drone that we are going implement will be helpful in spraying fertilizers, pesticides and crop protection products while being controlled by a single person operating from a safe area at the ground. By changing the type of container used, the device can be used for spraying fertilizers, pesticides and crop protection products like manure etc. There by greatly reducing the time taken and maintaining the safety precautions for the farmer while spraying fertilizers and pesticides.

The device that we are going to implement is a combination of spraying mechanism on a hexacopter frame. The process of spraying the pesticides and fertilizer is controlled by means of a remote and android application. The information is fed through remote and android application that controls the functioning of valve to prevent the loss of pesticides and fertilizers. The body of the hexacopter aerial drone is mainly made of wood frame designed large enough for the use of propellers with a pesticide tank underneath with a capacity of 0.5 liter and a sprayer for spraying the pesticides effectively on an agricultural field and it also have a space for fertilizer storage. It is then mounted onto a hexagonal body with a brushless motor at the end of each arm that carries propeller made of composites of carbon nylon and other additives.

1.2 Statement of Problem
The World Health Organization estimates that there are around 3 million cases of pesticide poison in each year and up to 220,000 deaths, primarily in developing countries. Organophosphates and carbonates, affect the nervous system. Others may irritate the skin or eyes. Some pesticides maybe carcinogens others may affect the hormone or endocrine system in the body. Even very low levels of exposure during development may have adverse health effects. Pesticide exposure can cause a range of neurological health effects such as memory loss, loss of coordination, reduced speed of response to stimuli, reduced visual ability, altered or uncontrollable mood and general behavior, and reduced motor skills and to cover larger areas of fields while spraying pesticides in a short span of time when compared to a manual sprayer.

On the other hand, it is known that agriculture is the backbone of our country. Even if that, the Ethiopian agricultural sector still uses traditional methods. Pesticides and fertilizers play a vital role for increasing agricultural products in quality and quantity. This project is to mainly overcome the ill effects of pesticides on human beings (manual pesticide sprayers) and used to increase agricultural products in quantity and quality by spray pesticide and fertilizer over large areas in short interval of time compared to conventional spraying by using an automated system.

1.3.1 Main Objective
In this project, our major objective is to change the obsolete methods being currently followed in Ethiopian agriculture systems by helping the farmers to spray the pesticides or fertilizers on crops using hexacopter drone system and to reduce the ill effects of the pesticides and fertilizers on human beings.

Specific Objectives
In addition to our main objective, we have done the following specific tasks and each of them plays a vital role for the final system that we are going to design and implement.

To design a mechanism for pesticide and fertilizer spraying tank
To assemble the hexacopter drone using necessary components
To control different parameters like spraying speed and the drone speed control
Interfacing ESC with Arduino UNO
1.4 Scope of the Project
The scope of this project covers design and implementation of the hexacopter drone for pesticides and fertilizers spray that requires less maintenance with low cost for Ethiopian farmers. There are two parts involved this project, namely the hardware and software. The hardware part involved the construction of the water turbine, preparing the appropriate tank for the pesticides and fertilizers, assembling different parts of the hexacopter drone and controlling the flight using remote controller. In the software part each sensor has its own background thread that constantly reads and updates incoming data, whilst monitoring for errors and logging. Android application also developed to control the spray of pesticide and fertilizer through our smart phone.
1.5 Expected Outcome
From this project, we will expect that the final hexacopter drone and design of sprayer had to meet the following specifications after the completion of the project:
The drone must be capable of flying and landing in stable manner.

The pesticide and fertilizer spraying process must be done perfectly.

Synchronization of hexacopter and spraying system should be done without any imperfection.
The flight controller that we are design must control the drone as the required direction.

1.6 Project Outline
The thesis out line of hexacopter drone for pesticides and fertilizers sprayer project contains six chapters. The first chapter starts with brief introduction of the project. This chapter describes the background of the project, the problem statement, objectives and the scope of the project. The second chapter is about the researches related to fields of the project that are mainly about the UAV system. Chapter 3 discusses the methodology of the project that includes programming of Arduino UNO using arduino software, the characteristics of different sensors and the overall construction of the hexacopter drone. Chapter 4 presents the system design and implementation of the project and some discussions. Chapter 5 deals about simulation result and discussion of the result. Finally, Chapter 6 will be conclusion, recommendation and future work. It will conclude the whole project and enhance or recommend some future works for the project.

This chapter describes the past and current researches that have been carried out that are related to this project. This survey investigates numerous aspects of sensors and the overall working system of the related projects.
The advent of UAV system as aerial sprayers has been recent and its adoption commercially is still limited. UAV system include both autonomous (means they can do it alone) drones and remotely piloted vehicles (RPVs). Japan’s Yamaha Corporation was the first to produce an unmanned aerial vehicle for spraying crop protection product 8.

2.1 Unmanned Aerial Vehicles (UAV)
An unmanned aerial vehicle (UAV), commonly known as a drone, as an unmanned aircraft system (UAS), or by several other names, is an aircraft without a human pilot aboard. The flight of UAVs may operate with various degrees of autonomy, either under remote control by a human operator, or fully or intermittently autonomously, by onboard computers.

Compared to manned aircraft, UAVs are often preferred for missions that are too dull, dirty or dangerous for humans. They originated mostly in military applications, although their use is expanding in commercial, scientific, recreational, agricultural, and other applications, such as policing and surveillance, aerial photography, agriculture and drone racing. Civilian drones now vastly outnumber military drones, with estimates of over a million sold by 2015 5. Originally developed for military purposes (Graham, 2010), drones now have manifold civil applications and can be flown with little to no training. This development has gained great momentum especially since the start of the 21st century (Rothstein, 2015) 4.

Multiple terms are used for unmanned aerial vehicles, which generally refer to the same concept. The term drone, more widely used by the public, was coined in reference to the resemblance of navigation and loud and regular motor sounds of old military unmanned aircraft to the male bee. The term has encountered strong opposition from aviation professionals and government regulators 2.

2.2 Types of Unmanned Aerial Vehicles
There is no one standard when it comes to the classification of UAV. Defense agencies have their own standard, and civilians have their ever-evolving loose categories for UAV. People classify them by size, range and endurance, and use a tier system that is employed by the military. For classification, according to size, one can come up to classify as multi rotor, fixed wing and single rotor 1.

2.3 Hexacopter Drone Configuration
The hexacopter has six motors mounted typically 60 degrees apart on a symmetric frame, with three sets of CW and CCW motors or propellers. Hexacopter are very similar to the quadcopters, but they provide more lifting capacity with the extra motors. There is also improvement in redundancy. If one motor fails, the aircraft can remain stable enough for a safe landing. The downside is that they tend to be larger and more expensive to build. The configuration of the hexacopter is shown in Figure 2.1 below.

Fig 2.1 Hexacopter configuration
2.4 Basic Components of Hexacopter Drone
The hexacopter is the result of different components such as frame, flight controller, transmitter and receiver, batteries, propellers, motors and ESCs that are assembled together to form the complete system. The frame or body is what holds everything together. It is designed to be strong, light weight, and consist of a center plate where the main flight controller chip and sensors are mounted and arms where the motors are mounted.

The BLDC motors are responsible for to turn the propellers, which is responsible for providing thrust for countering gravity and drag. Every rotor ought to be controlled separately by a speed controller. Motors are the primary force behind how hexacopter fly.

The electronic speed controller or (ESC) is a device that tells the motor how to spin. It is responsible for controlling the rate at which the motor spins the propeller.

The flight controller is the brain of the hexacopter. It sits at the center, controlling the firmware within the ESCs, consequently controlling the spin rate of the motors.
Lithium polymer (LiPo) batteries are the most famous power source for controlling drones today. Without going a lot into detail, the principle explanation behind this is because they are rechargeable and ordinarily have expansive limits.

A hexacopter has six propellers, three normal propellers that spin counter-clockwise, and the remaining three are pusher propellers that spin clockwise.

2.5 Working Principle of Hexacopter Drone
Hexacopter have five main components; the power supply, speed controller, the motors, the flight controller and power distribution board. All of these components are place on a hexacopter frame that places the six motors at equal distance with propellers 6.

The flight controller unit is the brain of the entire unit and it controls every function of the system. It also contains additional sensors to help flight stability.

The electronic speed controller (ESC) orders the motors how they need to spin. It may give simple sound but the ESCs are the most important components in the system. Each motor has to spin at variable speeds to ensure proper flight and handling.

The remaining components such as battery, motors, and power distribution board have their own applications. The battery provides the power, the power distribution board sends the power where it is needed and when it is needed, and the motors spin the propellers as directed.

2.6 Pesticide Spraying Methods
There are different methods of pesticide spraying techniques that are practiced today in all over the world. Among these methods backpack sprayer, Lite-Trac sprayer, Bullet Santi sprayer and the recently discovered aerial sprayer are available to increase agricultural products in quality and quantity and also to minimize human power. These sprayers also the minimize the time that required to spray agricultural field and gives more productivity in less input. Even if modern spryer techniques are available, Ethiopian farmers didn’t use them still due to the high cost of the technology.
Backpack sprayer: It is mostly a plastic made container which operates on the principle of compressed air with harness that allows it to carried on the operator’s back. There is hand operated hydraulic pump that forces liquid pesticide through a hose and one or more nozzles. After we determine the amount of mixture needed and proper amount of water to the tank for our application, the labor has to carry all the weight of the pesticides filled tank which causes fatigue to labor and hence reduces the human capacity. This sprayer is adopted throughout Ethiopian farmers due to its low price 7.

Fig 2.3 Backpack sprayer
Lite-Trac is a trading name of Holme Farm Supplies Ltd, a manufacturer of agricultural machinery registered in England and based in Peterborough. The Lite-Trac name comes from “lite tractor”, due to the patented chassis design enabling the inherently very heavy machines manufactured by the company to have a light footprint for minimum soil compaction. The company’s products are identifiable by the combination of unpainted stainless steel tanks and booms with bright yellow cabs and detailing. A Lite-Trac crop sprayer, or liquid fertilizer applicator, mounts onto the SS2400 Tool Carrier centrally between both axles to maintain equal weight distribution on all four wheels and a low center of gravity whether empty or full. The stainless steel tanks are manufactured in capacities of up to 8,000 liters, whilst Pommieraluminium booms of up to 48 meters can be fitted 7.

Aerial Sprayer: Aerial sprayer is another type of spraying; it is beneficial for the farmers having large farms. This technique is not affordable by farmers having small and medium farm. It is modern technique in agricultural field. In aerial spraying the spraying is done with the help of small helicopter controlled by remote. On that sprayer is attached having multiple nozzles and sprayed it on the farm from some altitude. It is less time consuming and less human effort required to spray fertilizers 7.

In this chapter the block diagram representation of the hexacopter drone and its brief description, flow chart diagram of the system and its algorithms will be discussed. In addition to these, the spraying mechanism for both pesticides and fertilizers will be presented.

3.1 Block Diagram of Hexacopter Drone for Pesticide and Fertilizer Spraying
The overall block diagram of the system is given as shown in Figure 3.1 below.5095875264160Pump ON/OFF control
0Pump ON/OFF control

4476758890WIFI module
00WIFI module
16573505080Spray Tank
0Spray Tank
294322524130Spray speed controller
0Spray speed controller






2876550158116LIPO battery
0LIPO battery
Fig 3.1 Block diagram of hexacopter drone for pesticide and fertilizer spray
The figure 3.1 above demonstrates the block diagram of the overall system. The system energized from a rechargeable battery called LiPo cell. Lithium Polymer cells (LiPo) are a tremendous advance in battery technology for RC use only. The power distribution board (PDB) distributes power from the LiPo that runs to the other components of the drone. The six ESCs orders the six motors how they need to rotate. The system has six BLDC motors that functions to rotate the propellers. The flight control board (FCB) is the brain of the hexacopter which contains different sensors that determines how each of the hexacopter’s motors spin.
3.2 The Components Used in the Project
In this project we are use the following main components.

1.Frame with Integrated PCB
3.Arduino UNO Board
4.1000KV Brushless DC Motor
5. 30A ESC (Electronic Speed Controllers)
6. 11.1V 2200mAh 35C Lithium Polymer Battery3.2.1 Frame/body
The body or the frame of the drone is the component that carries everything together. It is design from strong and lightweight materials to avoid the side effect on the flight process. The frame consists of a center plate where the main flight controller chip and sensors with BLDC motors are mounted. It is mostly made of carbon fiber, fiberglass, aluminum or steel. Some cheaper, smaller models also use plastic. In our project, the body frame of the hexacopter drone is design from lightwood that are easily available in our surrounding to minimize the overall cost of the project.

3.2.2 Propeller
We use hexacopter propeller Kit is intended to be used with hexacopters. The propeller adapters fit all thin electric propellers with diameters of 8 inch. We use six propellers, 3 of them rotates in clockwise and the rest rotates counter clockwise direction.Those propellers are made from durable plastic. The specifications of the propellers are:
• Diameter:24cm.

• Thickness: 0.36 inch.

• Shaft diameter: 0.25inch.

• Propeller weight: 0.78 Oz (ounce) or 0.022Kg.

The propellers that we are used are shown on Figure 3.2 below.

Fig 3.2 Propellers
3.2.3 LiPo Batteries
Lithium polymer batteries, more commonly known as LiPo, have high energy density, high discharge rate and lightweight, which make them a great candidate for hexacopter applications. LiPo batteries used in RC are made up of individual cells connected in series and we use 3S LiPo. Each cell has a nominal voltage of 3.7V and a total voltage of 11.1V. The LiPo battery voltage affects BLDC motors RPM directly, therefore we can use higher cell count batteries to increase the hexacopter speed if the motor or ESC and other electronics support higher voltage.

LiPo battery is designed to operate within a safe voltage range, from 3.2V to 4.2V. Discharging below 3V could cause irreversible performance lost and even damage to the battery. Over charging above 4.2V per cell could be dangerous and eventually cause fire. Increasing the battery capacity gives longer flight time, but it will also get heavier in weight and larger in physical size. There is a trade-off between capacity and weight that affects flight time and agility of the hexacopter.

Battery Calculations: We must know and calculate the amount of energy that the battery consuming; hence the source required by the battery is;
Max source = discharge rate × capacity; the battery has a capacity of 2200 mAh and discharging rate of 25C. Therefore;
Max source= 25×2200mAh=55000mAh=55Amp; So, the max source i.e. ESCs should not exceed 55A, since we have selected a 30A ESC there is no problem, it is perfect battery. We should never discharge a Li-Po battery below 80% of its capacity.

Watt calculation of 3S LiPo: Watt = V(Voltage) × I (Ampere),but; I (Ampere) = (Max Efficiency) × (Max Current); 0.8×20A=16A
Watt of LiPo=11.1V×16A=177.6Watt, The actual LiPo battery is shown on Figure 3.3 below.

Fig 3.3 LiPo battery
3.2.4 BLDC motors
A brushless DC motor is a permanent magnet synchronous electric motor which is driven by direct current (DC) electricity and it accomplishes electronically controlled commutation system (commutation is the process of producing rotational torque in the motor by changing phase currents through it at appropriate times) instead of a mechanically commutation system .These motors are the primary force behind how hexacopter fly and they are like typical DC motors in the sense that coils and magnets are utilized to drive the shaft. The brushless motors do not have a brush on the shaft that deals with iterating the power in the coils, hence, the name “brushless” is used to call them. These motors have the responsibility of turning or rotating the six propellers as we order them through program instructions. A speed controller controls every rotor of the motor separately. This motors have 3 coils inside the center of the motor, which is settled to the mounting. On the external side, it contains multiple magnets mounted to the cylindrical structure that is appended to the turning shaft. Since the coils are fixed, there is no need for brushless. The actual physical diagram of the BLDC motor is shown on Figure 3.4 below.

Fig 3.4 BLDC motor
Construction of BLDC motor
BLDC motors can be constructed in different physical configurations. Depending on the stator windings, these can be configured as single-phase, two-phase, or three-phase motors. However, in our project we use three-phase BLDC motors with permanent magnet rotor are used. The construction of this motor is similar to three phase induction motor as well as conventional DC motor. This motor has stator and rotor parts as like all other motors.

The Stator of a BLDC motor made up of steel laminations to carry the windings. The windings are placed in slots which are axially cut along the inner periphery of the stator. These windings can be arranged in either star or delta. However, most BLDC motors that we are used in the project have three phase star connected stator.

The rotor of BLDC motor incorporates a permanent magnet. The number of poles in the rotor can vary from 2 to 8 pole pairs with alternate south and north poles depending on the application requirement. In order to achieve maximum torque in the motor, the flux density of the material should be high. A proper magnetic material for the rotor is needed to produce required magnetic field density.

Operation of BLDC motor
BLDC motor works on the principle similar to that of a conventional DC motor, that is on the Lorentz force law which states that whenever a current carrying conductor placed in a magnetic field it experiences a force. As a consequence of reaction force, the magnet will experience an equal and opposite force. In case BLDC motor, the current carrying conductor is stationary while the permanent magnet moves. When the stator coils are electrically switched by a supply source, it becomes electromagnet and starts producing the uniform field in the air gap. Though the source of supply is DC, switching makes to generate an AC voltage waveform with trapezoidal shape. Due to the force of interaction between electromagnet stator and permanent magnet rotor, the rotor continues to rotate.

It is known that the whole power system depends on selection of motor. So this project used Brushless DC motors its specifications are described below on Table 3.1.

Table 3.1 BLDC motor specification
Specifications Values
Kv 1000RPM/V
Max Current20A
Max Efficiency75%
Weight 47g
NO load current at 10V 0.75A
Poles 14
3.2.5 Flight Controller
The flight controller is the brain of the hexacopter drone. This board is what sits at the center, controlling the firmware within the ESCs, consequently controlling the spin rate of the motors. It mainly controls the rotation of the six ESCs and the gyro sensor. It takes the inputs from the receiver and adjusts the motor RPM accordingly, via ESC. In our project the flight controller is designed by using MATLAB Simulink and arduino UNO incorporated with gyro sensor.

3.2.6 Electronic speed controller
ESC stands for Electronic Speed Controller which is used to vary the speed, direction and possible to act as a dynamic brake, of a Brushless Motor. It converts the PWM signal from the flight controller or radio receiver, and drives the brushless motor by providing the appropriate level of electrical power. Most modern ESCs switch at a much higher rate, which makes them much more efficient by lose less power as heat in the controller. The maximum current usage of an ESC needs to be greater than the motor and propeller combination will draw. In terms of ESC, suggesting 20%-50% extra Amps is good to prevent the ESC from burnout. The ampere rating of BLDC motor is 26A so we considering the current rating of the ESC will be:
ESC amp rating = 1.2 to1.5 x max amp rating of motor
=1.2 to 1.5 x 20A=24A to 30A, therefore we can select the amp rating of ESC between ranges of 24A to 30A. Due to this, we have chosen the ESC of 30A. The hexacopter has six motors and its respective ESC, so all six ESCs will draw a total current of: 6*30A=180A.

Fig 3.5 Electronic speed controller
3.2.7 RC transmitter and receiver
The transmitter is the radio controller FS-i6X and the receiver is FS-IA6 with a six channel 2.4GHZ AFHDS 2A digital proportional RC system. The 1st four channels are generally used for flight controls and the last two are for other operations. It is used to control the hexacopter by sending reference values for roll, pitch, yaw and throttle. The operator can then control the hexacopter through its control system. The receiver must be connected to the flight controller, which needs to be programmed to receive RC signals.

FS-i6 Transmitter Specifications: The following table 3.2 bellow describes the specifications of the remote transmitter.
Table 3.2 specifications of the RC transmitter
Specifications value
No of Channels 6
RF Range 2.4-2.48GHZ
Low Voltage Warning ;4.2V
Weight 392g
power 6v
3.2.8 Gyro sensor
The gyroscope that we used is a sensor with L3G4200D model of 3-axis angular rate sensor (yaw, pitch, and roll) and used in the IMU systems to measure the rate of acceleration and position of the hexacopter. This module’s default communication setup is I²C. The Gyroscope module I2C is a bus slave. I²C communication is used to read and write to and from the Gyroscope’s data registers. The two signals need for I²C operation are the serial clock line (SCL) and the serial data line (SDA). The SDA line is bidirectional and used for sending and receiving the data to/from the interface. The configuration of the gyro sensor with arduino is shown on Figure 3.6 below.

Fig 3.6 Gyro connected to I2C port of Arduino
Specifications of gyro sensor:
Power Requirements: 2.7 to 6.5 VDC
Communication Interface: I2C (up to 400 kHz) or SPI (10 MHz; 4 ; 3 wire)
Operating temperature: -40 to +185 °F (-40 to +85 °C)
Dimensions: 0.85 X 0.80 in (2.16 X 2.03 cm)
3.2.9 WI-FI module
DC Motor drive
3.3 Thrust Calculation of the drone
We make sure that the BLDC motors must produce around 50% more thrust than the total weight of the hexacopter drone. This means that the motors will have enough extra thrust to control the drone in wind and during aggressive flight maneuvers.

The thrust required of a single motor is given by a general formula:
Thrust(T)=0.5x(total weight setup)The frame weight is 950 grams, and from other set up including sprayer we are getting a weight 350 grams. Therefore, the total weight of the drone is 1300 grams.
Required thrust = 1300×0.5 = 650 grams
Since we have six motors for hexa motor, T=6 x650=3900gramsThe actual amount of thrust that is produced by an individual motor is calculated using a formula:
T= (eta×P) ²×2×pi×r²×air density ^?Where; eta = propeller hover efficiency let us take it as 0.7 to 0.8
P= shaft power
r = radius of propellers in meters
Air density =1.22kg/m³, Voltage = 10V, Current =20A, Motor efficiency =75%=0.75, Eta=0.7
Therefore, P=voltage ×current ×motor efficiency=10×20×0.75=150 Watt
T=(0.7*150)2*2*3.14*0.122*1.220.33=11N, 11*0.101kg=1.111kg=1111grams. Hence, the thrust generated by each motor = 1111 grams.

Total thrust T=6*1111grams=6666grams=6.666kg
If we again choose any less efficiency in motor, then we take some factor of safety, assume if they work only 70% efficient work due to some factors we can produce thrust of:
T = 6.666×70/100 = 4.66kg, Therefore the minimum amount of thrust produced by all the motors is 4.66kg for stable flight.

Total flight time:
Max Flight Time = 80% × Max continous Amp draw (A)/Max Current of 6 ESCsMax continous Amp draw A = Battery capacity Ah × Discharge rate (C) =2.2Ah × 25C=55A
= 0.8 ×55180= 0.24hr = 60×0.24=14.4minutes
3.4 Modeling of The Hexacopter
The mathematical model of the hexacopter has to describe its attitude according to the well-known geometry of this UAV. More specifically, this aerial vehicle basically consists of six propellers located orthogonally along the body frame. There are three movements that describe all possible combinations of attitude. As shown on Figure 3.7 below the configuration consists three basic principal components; For successful hexacopter flying it is important to understand what roll, pitch and yaw is.

Roll: The roll control tells the hexacopter to move side to side. In order to roll to the right for example, the speed of the three motors at the left side of the hexacopter must increase, relative to the speed of the three motors on the right. This rolls down the right side of the hexacopter, resulting in a side-ways swaying movement. Conversely, in order to roll left, the speed of the motors of the right of the quadcopter should increase relative to the speed of the motors at the left.

Pitch: The pitch control tells the quadcopter whether to fly forward or backward. In order to pitch forward for example, the speed of the motors at the rear (back) of the hexacopter must increase, relative to the speed of the motors on the front. This pitches the nose (front) of the hexacopter down, resulting in the forward movement. This is achieved by either increasing the speed of the rear motors or decreasing the speed of the front motors. Conversely, in order to ‘pitch’ backwards, the speed of the motors at the front of the hexacopter must increase relative to the speed of the motors at the back.

Yaw: In this case, the rotation speed of diametrically opposing of three motors are increased or decreased, varying the torque in the direction of rotation of that motors. The diametrically opposing motors in a hexacopter rotate in the same direction, causing the hexacopter to rotate in the direction of the increased torque.

Roll (rotation around the X axis) is obtained when the balance of rotors 1, 2 and 3 (or 6, 5 and 4) is changed (speed increases or decreases). By changing the angle, lateral acceleration is obtained; pitch movement (rotation around the Y axis) is obtained when the balance of the speed of the rotors 1 and 6 (or 3 and 4) is changed. The angle change results in a longitudinal acceleration; yaw (rotation about the Z axis) is obtained by a simultaneous change of speed of the motors (1, 3, 5) or (2, 4, 6). The schematic structure of the hexacopter and the rotational directions of the propellers are shown below on Figure 3.7.

Fig 3.7 The structure of hexacopter and its frames
The hexacopter is considered as a symmetrical and a rigid body and therefore the differential equations of the hexacopter dynamics can be derived from the Euler angles. Consider two reference frames, the earth inertial frame and the body fixed frame attached to the center of mass of the copter. The starting point of the earth fixed frame is fixed on the earth surface and X, Y and Z axis are directed towards the North, East and down direction respectively and in this frame the initial position coordinates of the hexacopter is defined. The body fixed frame is centered on the hexacopter’s center of mass and its orientation is given by the three Euler angles namely; roll angle (?), yaw angle (?) and pitch angle (?). The position of the hexacopter in the earth frame of reference is given by the vector ? = x y z T and the Euler angles form a vector given as ? = ? ? ? T. The rotational matrix R gives the transformation from the body fixed frame to the earth frame is given by the formula:
R=cos? cos ? cos?sin?sin ?-cos?sin? cos? cos?sin?+sin?sin? cos ?sin? cos?cos?+sin?sin?sin?cos?sin?sin?-cos?sin? -sin?cos?sin?cos?cos? ……. (1)
Hexacopter have both translational and rotational motions. The equations for the translational motion are given as:
? = 1/m (cos? cos?sin?+ sin? sin?) U1-kftx ?/m
ÿ = 1/m (cos? sin? sin? – sin?cos?) U1-kfty ?/m ………………. (2)
ž= 1/m (cos? cos?) U1-kftz ?/m-g
The equations for the rotational motion of the three axis are given as:
……………………… (3)
From equation, 3 above the total system dynamics of hexacopter drone position and altitude is a 2nd order differential equations that are obtained and can be written as the following equations:
Jxx is moment of inertia about body frame’s x-axis
Jyy is moment of inertia about body frame’s y-axis
Jzz is moment of inertia about body frame’s z-axis
I is Moment arm
Jr Rotor inertia
m Hexacopter mass
Kf Aerodynamic force constant
Kt Aerodynamic translational coefficient
Forces and Moments:
The forces and moments induced on the hexacopter are responsible for its movement and overall attitude. Each of the forces can be broken into an x, y, and z component. As such, the equations of the net force and the net moment acting on the hexacopter’s body (Fnet and Mnet respectively) are provided as:
Fnet= ddt(mv)b+ ? × (mv)b………. (4)
Mnet= ddt(I?)b+ ? × (I?)b ………. (5)
Where I is the inertia matrix, v is the vector of linear velocities and ? is the angular velocity vector. The gravity vector, which is towards the center of the earth, is taken with respect to the craft coordinate system. Along with gravity, the only other forces to be considered are the forces generated by the propeller/motor combos. These forces combined with the force of gravity, allow us to solve the net force and momentum of inertia of the hexacopter.

Fg=mg-sin?cos?sin?cos?cos? bodyT……. (6)
The force of gravity (Fg) together with the force generated by the propellers and motors (FP) are equal to the sum of forces acting on the hexacopter Fnet:
Fnet= Fp+Fg ………. (7)
3.5 PID Controller Design
The PID controller is the most common control algorithm that is used to control feedback loops which makes the process variable close to the set point in spite of disturbances and variation of the process characteristics. In cases where there are external disturbances like wind or presence of unknown errors such as the mass of the quadrotor being unknown, PID control is used, which is a more complex version of the PD control. PID controller calculate error as the difference between a measured process variable and desired set-point. PID can solve the existing problems and improve the dynamic response of the hexa UAV. The controller attempts to minimize the error by altering the process control inputs. If a PID is not used then on application of a throttle, the hexacopter will reach the desired position but instead of being stable, it’ll keep oscillating around that point in space.

There are three control algorithms in a PID controller; P, I, and D. P depends on the present error and reduces the rise time and the steady state error; I depend on the accumulation of past errors and eliminates the steady state error; while D is a prediction of future errors based on the current rate of change. It increases the stability of the system and also improves the transient response. The main purpose of the PID controller is to force the Euler angles to follow desired trajectories. The objective in PID controller design is to adjust the gains to arrive at an acceptable degree of tracking performance in Euler angles. The block diagram for a PID controller is shown below on Figure 3.8.


Fig 3.8 PID Controller Block diagram
The total equation of classic PID controller output is:
ut=Kp*et+ Ki* 0te?d?+ Kd* ddte(t) Where; Kp K p {displaystyle K_{ ext{p}}} is the proportional gain, Kd is the derivative gain, Ki K i {displaystyle K_{ ext{i}}} is the integral gain,
tK d {displaystyle K_{ ext{d}}} e ( t ) = S P ? P V ( t ) {displaystyle e(t)=mathrm {SP} -mathrm {PV} (t)} is the time or instantaneous time ,
e(t) = SP – PV(t) is the error (SP is the set point, and PV(t) is the process variable), and
? t {displaystyle t} ? {displaystyle au } is the variable of integration (takes on values from time 0 to the present,t {displaystyle t} t).

3.5.1 Characteristics of P, I, and D Controllers
Generally there are three PID loops with their own coefficients, one per axis, so we set P, I and D values for each axis (pitch ? , roll ? and yaw ?).A proportional controller ( Kp) will have the effect of reducing the rise time but never eliminate the steady-state error. An integral controller (Ki) will have the effect of eliminating the steady-state error, but it may make the transient response worse. A derivative controller (Kd) will have the effect of increasing the stability of the system, reducing the overshoot, and improving the transient response.

3.5.2 PID Tuning
There are two types of PID tuning, automated and manual. Hexacopter is non-symmetric multi-copter in which usually tune one parameter at a time is required: P, I or D using fine tune. Manual tuning is done by doing various experiments which different conditions and parameter values. Automated tuning is done using the automatic PID control tuning option given in MATLAB tool kit. If the system must remain online, one tuning method is to first set Ki and Kd values to zero. For P gain, we first start low and work, until we notice it is producing oscillations. Then fine-tune it until we get to a point it is not sluggish ; there is no oscillation. For I gain, again we start low and increase slowly. Roll and Pitch our hexacopter left and right, and we pay attention to the how long does it take to stop and stabilize. For D gain, it can get into a complicated interaction with P and I value. When using D gain, we need to go back and fine-tune P and I to keep the plant well stabilized.

Flow chart for pilot Inputs
After we start, at initial stage we cheek the hexacopter starts working and ready ON the receiver and remote to calibrate accelerometer, gyroscope and calibrates ESC for all motors using flight controller. Then we will receive different commands and instructions that indicate the behavior of hexa copter such as up and down, left and right and forward and backward conditions. Then we read different data from the displayed remote such as the set points for pitch, roll and yaw. The flow chart for pilot inputs is shown below on Figure 3.9.

Fig 3.9 Flow chart for pilot input
3.6 Pesticide Spray Mechanism
3.6.1 Introduction
Pesticides are substances or mixtures that are obtained from natural products or chemically synthesized, which intended for preventing, destroying, repelling or mitigating any pest to control disease of certain kinds of agricultural plant. These pests can be insects, mice and other animals, unwanted plants (weeds), fungi or microorganisms like bacteria and viruses. There are different categories of pesticide are there but our project focuses solely on agricultural use of pesticides. Pesticide application is the process of applying or delivering various types of pesticides to target pests and weeds to increase and improve food production, protect public health, decrease pest-related property damage and injury, and reduce nuisance pest and weed populations. In agriculture, pesticides are used primarily to control nuisance weeds (herbicides), insects (insecticides), fungi (fungicides), nematodes (nematicides), and rodents (rodenticides). Agricultural pesticides are used in the greatest quantities to protect field and orchard crops such as “teff, bekolo, sindie and gebis”. In Ethiopian Agriculture Pesticides may be applied in a number of different ways as liquids and dry solids according to the nature of the environment. Liquid pesticides are usually applied as a spray of an aqueous solution or as oil droplets containing a solution or suspension of active ingredient. Since most of Ethiopian farmers are using liquid pesticides this project is also deals about the design and mechanism of liquid pesticide.

Although pesticides are important in agriculture to insure high crop yields and to improve food security their extensive or long use in agricultural areas can cause serious contamination of air, water, soil and other natural resources through various pathway.

Pesticides are applied to crops by means of spraying. In Ethiopia all most all farmers in the country uses labor force to spray those pesticides and fertilizers to their farm in traditional way. Conventionally the spraying is done by labors carrying backpack sprayer. During this time, pesticide exposure affects the human health in various ways and causes neurological and skin diseases like asthma, allergies, hypersensitivity, cancer, hormone disruption, and problems with reproduction and fatal development. To overcome all these ill effects of the pesticides and fertilizers on human beings and also to spray pesticides over large areas in short interval of time we are going to implement and use an automated aerial pesticide sprayer.

3.6.2 Design of pesticide Sprayer
Sprayer is mechanical device that are specifically designed to spray liquid like herbicides, pesticides, fungicides and fertilizers to the crops in order to avoid any pest and control the unwanted plant species quickly and easily. They have number of different varieties. In Ethiopian farms mostly hand operated and backpack spray pumps are used for pesticide spraying purpose. The main drawback of hand operated spray pump is that the user can’t use it for long time continuously as he gets tired after some hours.

So to minimize these problems of the farmers we are designed pesticide sprayer which is hold and sprayed by the hexacopter drone. To design this sprayer system, we use different simple materials which are obtained in our environment easily to make simple and cost effective.

Materials needed to design the pesticide sprayer: We use the following materials as row material for sprayer design.

Plastic container with 0.5L capacity as pesticide storage tank.

Plastic pipe with diameter of 0.5cm
9V DC motor with 150 RPM
Two similar size plastic capes with area of 50cm2
Curved turbine blades made from light aluminum
Central rotating light metal shaft
Turbine design
The size of the turbine depends on the amount of power required, whether electrical or mechanical. An actual diameter of 4cm turbine blade is provided at this project. Each blade is inclined at 450 for the purpose of perfect distribution of water to the outlet pipe. The overall designed pesticide sprayer device is shown below on Figure 3.10.

8191501524000043053001403352019300140335tankinlet pipeDC motor and turbine
Outlet pipenozzle
Fig 3.10 Pesticide sprayer nozzles and tank
Working principle of the sprayer:
The sprayer that we are designed is a much smaller, lightweight in which the kinetic energy of the water is converted into mechanical energy through the use of correctly placed pressure nozzles and blades.
However, as a typical sprayer turbine design has lots more blades attached to this central shaft, this rotation causes the next blade behind it to come into contact with the entering water pressure causing the turbine to rotate some more and so on. As the turbine continues to rotate, the water becomes trapped in between the turbines blades and is pushed along by the rotational movement of the turbine. At some point along the rotational angle of the turbine blades, the water encounters an opening in the casing, usually located at the center, which allows the water to exit at the high pressurized nozzles for sparing purpose.

The light metal curved blades are attached at the central rotating shaft at an angle of 450. This rotating shaft together with blades are enclosed by the two plastic capes to avoid external air. The shaft is attached with the external DC motor: as a result, when the motor gets energized the shaft start to rotate at a speed of almost equal to the rotation of the motor initially. Then the pipe that is connected to the pesticide supplier tank starts to absorb the pesticide water at high pressure. Then the pesticide water flowing through the casing of the enclosed turbine, hits the blades of the turbine producing torque and making the shaft rotate due to the velocity and pressure of the water. From the enclosed plastic capes there is another output pipe in which three nozzles with high pressure are attached.
We can guide the opening and closing of the nozzles as we want by control the speed of the motor. Since the sprayer is aerial spray we use a program instruction and android application to control the DC motor and sprayer nozzle at the ground control station using smart phone. When we give a command to the DC motor to “stop” and to “start” through a program instruction and the application through our smart phone, the outlet nozzles are open and close.

After the hexacopter drone fly and gets its target agriculture field, we give a “start” command to the DC motor. When we give this command the LiPo battery gives 9V source to the motor and the motor starts to rotate the shaft with its blades. The rotation of the blades creates high pressurized and compressed air which leads to the absorption of the pesticide chemical through the plastic pipe. The absorbed pesticide water strikes the metal blade that are inclined at 450. These blades have the ability to disturb the inlet pesticide water to the outlet pipe. At the outlet pipe three nozzles are connected with high pressure. As a result, we can spray the crop with sufficient pesticide concentration. We can increase the amount of pesticides that leave out through the nozzles by increase the speed of the motor. As the speed of the motor increase the rotation of the blades also increase which creates higher compressed and pressurized air which leads the absorption of more concentration of pesticide water. The amount of pesticide concentration is directly proportional to the speed of the DC motor which connected at the shaft of the blades.

Since we use the hexacopter drone for spray purpose aerially the tank status or amount of concentration of pesticide remaining in the tank can’t be cheek with our naked eye. Therefore, we can know the tank status with a level sensor that installed in the tank. The sensor gives the tank status information signal continually to our smart phone. As a result, when the tank gets low we decided to land the hexacopter properly.
But using the level sensor to know the tank status have its own limitation as we have recommended by professional persons that study about the agricultural pesticides. To use level sensor a skilled man power is needed during the spraying time. This is not suitable for Ethiopian farmers. So to avoid this problem we are recommend to use another technique called speed adjustment.

In speed adjustment technique, the hexacopter speed is adjusted to cover a certain hectare of field at a known time with known amount of pesticide water in Liter. As we obtain information and data from the professional persons one-hectare agricultural field covers 50×50m=2500m2. For this specified filed we need 25 liter of pesticide water. So to spray this amount of pesticide on one-hectare agricultural field the speed of the drone and the time taken to cover all the field is calculated.

Block diagram of sparing mechanism:
393557712283400Inlet pipe
4373195255473356969028626Blade and pump
00Blade and pump

3277210161951003752698132690005259629337515Motor drive
00Motor drive
Outlet pipe
4982845142240001798625133071Nozzle 1
00Nozzle 1

2362200368300Nozzle 2
00Nozzle 2
5274259114554Source, 9V
00Source, 9V
359176348717Nozzle 3
00Nozzle 3

Fig 3.11 Sprayer block diagram
3.7 Design of Fertilizer Sprayer
In a developing nation with a large population like Ethiopia, the agricultural sector has its own importance in terms of revenue and food security. The designed automatic fertilizer spreader facilitates the farmer by providing automation in spraying the fertilizer on their crops in the farms, increasing the productivity with reducing the working time and effort of manual operation. A method is generated to spread the fertilizer over a fallow land by dropping the fertilizer over the impeller disc.

Materials required:
1) Hopper: it is hard plastic container like PVC with a conical cross section area that is used for convey the fertilizer to the cylindrical nozzle. The Fertilizer Spreader machine should satisfy the following objectives:
Fertilization process should be less time consuming
Light weight
Less cost
User friendly
Specifications of hopper
Surface area=?r2 + ?rl=0.00785m2+0.01256m2=0.02041m2
2) Cylindrical nozzle: It is a thin cylindrical plastic nozzle which is used for spread the fertilizer on the crop. Its nozzle is controlled by a program which is “open” and “close” as we want in a certain delaying time. The opening and closing of the nozzle is controlled by the help of servo motor.
Specifications of cylindrical pipe
Height =5cm
Diameter =1.5cm
Area = 2?r2 +2?rh=3.5325cm2+23.55cm2=27cm2
Servo motor: Agriculture drones can perform variety of functions such as fertilizer and pesticide spraying, weather forecast and field monitoring etc. But our project is mainly concerned on sprayer in the agricultural field. This is achieved by using a simple circuit of servo motor controlled with the help of Arduino Uno. A mobile application is created using android application and the sprayer circuit is controlled via this application. The communication medium is WI-FI module and a slider is provided in the app in order to move the direction of motor. The servo motor is connected with the base, which is used to close and open the cylindrical nozzle as we want through program instructions. When the base moves down the nozzle become open and the fertilizers move down to the farm appropriately and when we want not to spray the fertilizer the base moves up and the nozzle becomes closed.

Fig 3.12 Servo motor
Specifications of servo motor:
Current=7.2 mA to 8 mA
Rotational range=600

315277460325cylindricalservo motor
Fig 3.13 Fertilizer sprayer tank
This project include hardware assembly, design and another part is software design. We use LiPo battery, gyro, brushless motor, ESC, servo motor and RC transmitter and receiver for the hardware design and we connected these components with microcontroller. Arduino UNO microcontroller is more suitable for establishing and implementing our project. Due to this and its compatibility, we select this microcontroller.

4.1 Receiver configuration with arduino
It is a most complex part in this project. In this circuit diagram of receiver configuration, it reads the signals released from the remote to the specific channels. This receiver is a fly sky receiver which has 6 channel outputs. We use 5 individual channels for this hexacopter drone project. Channel 1 for roll, channel 2 for pitch, channel 3 for throttle and channel 4 for yaw control. On receiver channel 1, 2, 3 and 4 signal out pin individually connected to arduino pin 8, 9, 10 ,11 and 12. Receiver VCC connected to arduino +5v out pin and GND to GND. After upload the code on arduino, we read on serial monitor every channel data individually and we can vary or control those signals by the remote controller. Generally, receiver receives 1000 to 2000 micro second plus. On the serial monitor we read 1025 micro second plus for channel lowest value and 1504 micro second plus is middle value and 1956 micro second is highest value.

Fig 4.1 Receiver configuration with arduino
4.2 Gyro interfacing with arduino
Gyro is a low-power three-axis angular rate sensor able to provide stability of zero rate level and sensitivity over temperature and time. It is very accurate to convert analog values to digital because it has a 16bit analog to digital converter hardware for each channel. It has the capability of capturing x, y and z channel at the same time. The data sensed by gyro is analyzed by arduino. The gyro data is compared with the pilot input data and the difference of the two data is feed to the PID flight controller as error. Then the flight controller minimizes this error, as a result the drone is going to stable.

During interfacing gyro is connected with SDA and SCL pin to arduino analog pin A04 and A05 respectively. VCC and GND are connected to arduino +5v and GND respectively. After uploading code and when we observe on serial monitor mode X, Y, Z directional change value is shown. All value will zero for zero directional change. Negative and positive value will show for directional change. The gyro sensor configuration with arduino UNO is shown below on Figure 4.2.

Fig 4.2 Gyro configuration with arduino
4.3 ESC interfacing with arduino
As we discussed before ESC have the responsibility of controlling the speed of BLDC. Generally, it supplies voltage to BLDC with high current flow. It receives PWM signal from arduino and convert it to voltage feed. ESC powered from rechargeable LiPO battery. ESC signal pin connected to pin change interrupt pin of arduino, digital pin 4 or 5 or 6 or 7. The three phase voltage out plug directly connected to thee brushless motor.

To test motor run or not ESC need PWM signal from the receiver. In here we connect ESC signaling pin directly to channel-3 signal out pin of receiver module. Because receiver produce PWM signal. The receiver powered from ESC, built-in voltage regulator provides +5V to receiver module. The configuration of the ESC with receiver is shown on Figure 4.3 below.

Fig 4.3 ESC configuration
4.4 Pesticide Sprayer motor interfacing with arduino and android application
In android control system the, the chemical pesticide sprayer system is controlled with mobile device like smart phone or a tablet that runs android operating system, which contains ESP 8266 WI-FI module (wireless Fidelity) module. Intelligent design using Wi-Fi wire-less control spraying system, send data signal to android mobile phone display, mobile phone via a wireless Wi-Fi spray to control the start and stop of the motor. Design of high-speed wireless access and transmission characteristics of Wi-Fi-based, wireless router as a network connection point, data transmission to the wireless router, wireless router via Wi-Fi network to send data out, android smart phones connect to a wireless router Wi-Fi network, a wireless router receives data and display on the phone. In our android application development, we have designed three buttons, namely “START, STOP and LEVEL” buttons to control the speed of the DC motor. The DC motor is connected directly with the central part of the turbine. As a result, the movement or rotation of the turbine is determined by the movement of the DC motor.
START button: When we press the “START” button from the smart phone, the DC motor gets active and starts to rotate resulting the turbine rotation. When the turbine rotates the blades absorb pesticide water from the tank through inlet pipe and distribute to the outlet nozzles for spraying purpose.
LEVEL button: This button is used after the motor gets start and spray process was beginning, if we want to increase or decrease the output pesticide level according to the amount of the pests or weeds present. This button is a sliding button and when we slide it from left to right the speed of the motor will increase and amount of pesticide water release through the nozzles also increase. While we slide the “LEVEL” button from right to left motor speed will be decrease as a result the amount of pesticide release also reduce. All this activities of motor control are performed by the help of DC motor drive that is directly connected to the motor and used to vary the speed of the motor as we want by android application instructions.

STOP button: This button is applicable when we have finished the spraying process or when a certain condition is occurred that prevent us from spraying. It directly stops the rotation of the motor.

Fig 4.4 ESP 8266 WI-FI module configuration with arduino
Wi-Fi module
Fig 4.5 Over all DC motor speed controller configuration
4.5 Fertilizer sprayer motor interfacing with arduino

4.6 Development of the Whole System
4.7 Cost Estimation
The total cost estimation of the project is calculated on the table 4.1 below. Relative to the cost of the hexacopter drone that are present today, it is very cost effective.

Table 4.1 cost estimation of the overall project
Equipment list Quantity Price in birr
Brushless DC motor 6 150*6=900
Electronic Speed controller 6 140*6=840
Receiver/Transmitter 1 2500
Arduino UNO 1 700
Wi-Fi module 1 250
LiPo battery 2 300
LiPo battery charger 1 250
Wood arm
1967230441960001 50
Servo motor 1
DC motor 1
Wi Fi module 1
Motor driver 1
Others Total amount of price:5790Birr
5.1 PID controller Simulink of hexacopter
The hexacopter dynamic motions are simulated by using MATLAB software using PID controller. The MATLAB Simulink block with sub-system block and results are shown in Figure 5.1 below which are pitch, roll and yaw responses of hexacopter respectively.

The Roll and Pitch PID controllers receive the command angles and the feedback angles and process these inputs every 10 ms. The output of both roll and pitch PID controllers are the roll and pitch corrections. The roll correction is passed to the mixing stage to produce the appropriate PWM signals for the right and left brushless DC motors. Furthermore, the pitch correction is used in the mixing stage to generate the PWM signals for the front and rear brushless DC motors.

5.2 DC motor speed control simulation result
5.3 Speed control of ESC
5.4 Tests and Results of PID controller
In the tests of the controllers during flight, the gains were adjusted, because the initial values of the design did not show a suitable performance. The derivate gains in particular had to be drastically decreased because their effect destabilized the system.
For roll, the proportional gain was set to Kp = 0.75, while the proportional gain for pitch resulted in Kp = 0.7. In both cases, the derivative gain was reduced to Kd = 0.02 and the integral gain was increased to Ki = 0.4 due to an error in steady state.

The proportional gain of the yaw controller was increased to KP=0.9; the derivative gain was decreased to Kd=0.05 and integral gain Ki is equal to 0.3. In yaw control, it is important to consider the discontinuities of the signal and to correct the controller performance on those points to avoid system failures. The controller implemented corrects the discontinuities and its response is acceptable as shown on the Figure below.

The altitude controller’s proportional gain was adjusted to Kp = 0.6; the derivative gain to Kd = 0.45; and the integral gain to Ki = 0.2.

Fig 5. Roll stability of the hexacopter
Fig 5. Pitch stability of the hexacopter
Fig 5. Yaw stability of the hexacopter
The overall objective of this project endeavor was to approach the design of automatic pesticide and fertilizer sprayer whose application is done by a man-portable hexacopter drone while being controlled by a single person operating from a safe and secure location to solve the problems related with quality and quantity of Ethiopian agricultural products. The derivation of the modeling equations and the raw implementation of a simulation model and controller design allowed us for the understanding of the physical characteristics that dictate the behavior of the drone. The right components have been chosen then the interface between components has been done, finally the algorithm was developed and the code was implemented in Arduino Uno. After implementation, the angular velocities of brushless DC motors have been controlled by RC remote controller, then the angular rates readings from the gyro were calibrated, obtained, filtered and processed then the PID controller gains were applied and the hexacopter was able to roll, pitch and yaw. The stability of the hexacopter is depend on the PID tuning.

By such successful implementation of such project, effective pesticide and fertilizer sprayer can be archived using hexacopter drone. The sprayer we have designed can also vary the amount of spray by varying the speed of DC motor. The exposures of highly toxic pesticide to human beings can be prevented since there is no direct contact. Implementing this project can hasten the pesticide spraying process and cover large area in short time. Encounters with venomous snakes that can be found regularly in agricultural field can be prevented.
In Ethiopia the drone, application is untouched even the technology is latest technology. Drones can perform multi applications such as surveying crops, monitoring diseases, determining precision application rates of pesticides and fertilizers, monitoring irrigation, geographical studying, planting and harvest crop and so on. Therefore, we recommended that the Ethiopian government should be plan and implement drone technology to make life easy.

6.3 Future work
Presently, the drone we have assembled is for spraying crop protection products only, but there are a lot of future scope for this concept such as crop surveillance for monitoring the health of the farm from a safe location. For anyone who wants to study and work on agricultural application drones, it can be add the following futures for better application and for best performance.

Flight time can be increased by increasing the battery capacity
Larger area can be covered by using more nozzles which can be arranged in the form of array
Weight lifting capacity of the drone can be increased by propellers and arms together with motors
Pesticide and fertilizer carrying capacity can be increased by increasing the size of the tank
3 Deccan Chronicle-vijayawada uav drone
8 John Villasenor, “Drones and the future of domestic aviation”, University of California Los Angeles, Vol. 102, 2014
9 Alaimo, A., Artale, V., Milazzo, C.L.R., Ricciardello, A.: Comparison between Euler and quaternion para-metrization in uav dynamics. In: AIP Conference Pro-ceedings (2013 PID Controller Applied to Hexacopter Flight (PDF Download Available). Available from:
10 “Hexa copter for pesticide spraying” Misbah Rehman.Z, Kavya.B, Divya Mehta, International journal of Scientific and Engineering Research, Volume 7, Issue 5, May-2016
11 Prof. Swati D Kale, Swati V Khandagale, Shweta S Gaikwad, Sayali S Narve, Purva V Gangal “Agriculture Drone for Spraying Fertilizer and Pesticides” Volume 5, Issue 12, December 2015
12 “Hexacopter UAV based Fertilizer and Pesticide Spraying System” ISSN No: 2414 – 6242
13 A.A.C. Fernando, and Ricardo, “Agricultural Robotics, Unmanned Robotic Service Units in Agricultural Tasks”, lEEE Industrial Electronics Magazine, pp. 48-58, Sep 2013.

14 C. Zhang, J. M. Kovacs,” The application of small unmanned aerial systems for precision agriculture: a review”, Precision Agriculture, Springer, 2012.

15 Fan Q N. The research on the pesticide spray system Using unmanned helicopter.


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