ELECTRONIC ENGINEERING, TELECOMMUNICATIONS AND INFORMATION TECHNOLOGIES – APPLIED ELECTRONICS [303180]

UNIVERSITY “POLITEHNICA” [anonimizat] – APPLIED ELECTRONICS

DIPLOMA PROJECT

PROJECT COORDINATOR:

ASSOC. PROF. [anonimizat]: [anonimizat]

2019

UNIVERSITY “POLITEHNICA” [anonimizat] – APPLIED ELECTRONICS

FIRST PERSON VIEW QUADCOPTER

PROJECT COORDINATOR:

ASSOC. PROF. [anonimizat]: [anonimizat]

2019

Academic Honesty Statement

I, [anonimizat], hereby declare that the work with the title “FIRST PERSON VIEW QUADCOPTER”, [anonimizat] "Politehnica" [anonimizat], based on my work.

[anonimizat], [anonimizat].

The thesis has never been presented to a higher education institution or research board in the country or abroad.

[anonimizat], [anonimizat]. I understand that plagiarism is an offense and is punishable under law.

[anonimizat].
I understand that the falsification of data and results constitutes fraud and is punished according to regulations.

[anonimizat] 21.06.2019

1.INTRODUCTION

1.1 INTRODUCTION

Drones and quadcopters have been revolutionized flight. These kind of drones help humans to take to the air in new and profound ways. Today’s [anonimizat].These nifty devices capture awesome aerial images and enable augmented reality game playing as well.

[anonimizat], especially their aerodynamic features and uses pique curiosity.

For my diploma project I [anonimizat] I need, [anonimizat] I was trying to build an FPV quadcopter using my own configuration for the components.

Before I start to build the quadcopter I decided on some requirments to achieve in my final configuration for the drone and for personal achievments i understand how a drone works and I was able to apply notions that I learned in these four years.

1.2 WHAT IS AN FPV QUADCOPTER?

Drones belong to a class of aerial vehicles called as Unmanned Aerial Vehicles(UAVs) and these devices can take to the air without pilots. [anonimizat]-controlled flight plans integrated into the system. These systems are working with Global Positioning Technology called GPS to guide and track all their movements.

An FPV quadcopter (quadrotor) is a flight drone, a multirotor helicopter which is built for high speed and agility that uses only four rotors to fly. This kind of drone is used speacially for racing competitions or just for fun.

1.3 THE HISTORY OF DRONES

These kind of devices have a rich history and with the help of computer technology and also engineering, they have developed in stunning ways.

Planes with no pilots appeared after the First World War, where the early version of today’s aerial torpedo was developed by Elmer Sperry of the Sperry Gyroscope company. The American military turned also the Standard E-1 planes into drones. The Larynx was a little monoplane that was able to fly on autopilot after being lunched from a warship. The US military experimented with these kind of remote-controlled drones and tried to build a variety of planes and drones.

Engineers developed quadcopters to solve problems that helicopter pilots had with making vertical flights. The technology has advanced drones and quadcopters dramatically, in the past decade some companies like Heli-Max, Parrot, DJ Innovations have lunched a lot of mini quadcopters.

Quadcopters have the qualities of different helicopters, which are either pitched or co-axial.The pitched ones are very agile and wind resistant and co-axial models depends on two layers of rotors and are more stable.

The pilots of these devices control them with the joysticks on a radio remote-controlled transmitter and a radio receiver process the pilot’s instructions.

A quadcopter use different aerodynamics. Newton’s law of motion states that for every action, there is an opposite and equal reaction. The 4 motors of a quadcopter ,two are moving clockwise and the other two moving counter-clockwise, negate any torque or force on the fuselage/frame and they stabilize the movement and function.

Figure 1.1 (Motor spin direction for quadcopter movements) [1]

1.4 WAYS TO USE QUADCOPTERS

1.4.1 Research

University researches are using these drones as a research tool, because they gather information needed for work in robotics, some real-time systems and also in flight control. These little and durable devices can survive in different enviroments and also can go into dangerous places on behalf of researchers helping to solve many difficulties with cost and logistics.

1.4.2 Military and law enforcement

The military scientists from different countries build quadcopters and drones for reconnaissance and combat purposes. Law enforcement agencies use them also in search and rescue missions as well because these little devices scour inaccessible areas for disaster survivors and the agencies also use these devices to uncover criminal activity.

1.4.3 Comercial use

In these days, many pilots use these quadcopters/drones to capture aerial videos and images. Some of them use Go Pro cameras for good captures during flight time.

1.5 HOW TO BUILD AN FPV QUADCOPTER?

If you are new in this area and you want to build your first quadcopter you need to buy some essential components and then you can make some upgrades in time.

The basic components that we need for the build and I also used for my build are:

Frame

Motors

ESC – electronic speed controller

FCB – flight controller board

PDB – power distribution board

Radio transmitter and receiver

Propellers – one for each motor ( 2 clockwise direction , 2 counter clockwise direction)

Lipo battery

Battery charger

Video camera

Video transmitter

Video receiver

2. COMPONENTS

2.1 FRAME

The frame is the main structure of an quadcopter that contains all the components of the build. The ideal frame for a quadcopter should be lightweight, strong and also offer a good balance. There are two types of frame: generally the stronger frames are heavier and are more stable in the air and the lighter frame that are more efficient and nimble.

For FPV racing speed the speed of the quadcopter is the top priority in a build so we need to choose a lightweight frame that will also react more quickly to stick inputs and also the acceleration will be more faster.

Quadcopter frame have an significant impact for our performane: weight distribution, rigidity and aerodynamics. Also the model of the frame determines how easy is to install all the quadcopter components and put all of them together in the frame. In these days all the frames are designed from different materials and shapes to make them weigh lighter, have a nice aspect and also to provide a good protection for components when a crash happens.

A frame can be made from different materials such as wood, 3D printed plastic, injection molded plastic, aluminium, PVC pipes, fibre glass.

The carbon fiber frames remains the most popular material for an quadcopter thanks to its relatively low cost and excellent properties:

Strength – carbon fiber is knows to be durable

Rigidity – offer stability and flight performance

Light weight – offer more speed, a better agility and a longer flight time

Also we have a few disadvantages if we choose a fiber carbon frame:

Carbon fiber is electrically conductive ( can cause a short circuit and burn the components if we have live wires touching the frame )

Blocks the radio frequency signal so we must to be sure that the antennas are not hidden inside the frame

We also must be carefully what size we are choosing for the frame because this determines the choice of the components that we are using in the build. The frame size has great influences for the following aspect for our quadcopter:

Propellers size

Motors size

Electronic speed controller (4-in-1 or individual)

Air resistance

Total weight

Camera compatibility

Moment of inertia of the quad

Motors are mounted on the end of each arm of the frame. The futher away they are from the centre of the frame, the larger the moment of inertia, which introduces a tendency for angular acceleration and deceleration during the flight.

Here we can see a simplified table with quadcopter frame sizes and maximum propeller size they can use:

Table 2.1

The frame shape is determined by how the arms are connected with the centered body.So we have the following frame models:

H model

X model

Hybrid X model

Stretch X model

Square model

Stretch Plus model

Figure 2.1 (H model) [2] Figure 2.2 (X model) [3]

Figure 2.3(Hybrid X model) [4] Figure 2.4 (Stretch X model) [5]

Figure 2.5( Square model) [6] Figure 2.6(Stretch Plus model) [7]

2.2 MOTORS

The motor is positioned under the propeller and also controls its speed and rotation. The choise of the motors plays an important role in the success of the final configuration and this is also the point when specifications start to get complicated. To choose the right motors for our configuration we must to know a few criteria.

2.2.1 Wheight of the quadcopter

First criterion for selecting the right motors for the quadcopter is to have a clear idea about the total weight of drone itself. We must to approximate the total wheight by simply calculating weight of each component of the drone. Also once we know the overall size of frame we cand determine the right propeller size. The idea about size and weight of propellers will help us to know about the overall thrust of motor that they will need for a perfect lifting of the quadcopter during the flights. This decision will help to maintain the speed in air and the weight will also contribute in flight time adjustments.

2.2.2 Thrust to weight ratio

The selected motor must be capable enough to produce the power to keep the quadcopter safe during windy weather and also in the time of flight maneuvers. For example if our quadcopter have an weight of 600 grams then we need to pick a motor that can generate at least twice amount of thrust.

2.2.3 Efficiency

The formula used for motor efficiency calculation is “thrust/power” used in Watts; its overall unit becomes g/W. So if we have higher value of g/W rating this means that the motor is more efficient and it will assist drone in longer flights.

2.2.4 Torque

Torque range helps us to define the ability of motor to hift between RPM (rotation per minit) value. If the motors have high torque value then it will naturally lead to snappy response as RPM will accept faster changes ( good for freestyle flight ) . So the high torque motors are able to generate a faster response rate and the drone can move between different RPM rating easily and efficiently.

2.2.5 Pole Count

Another important thing is motor pole count. The motors with higher pole count are able to produce greater torque value but at the same time will need more voltage from the battery. The motors with low pole count for a higher RPM will use smaller blades and will serve with smaller lift from ground.

2.2.6 Motor type

For quadcopter there are two types of motors: Brushed DC motor and Brushless DC motor.

Figure 2.7 (Motor type) [8]

2.2.7 Movements

For a successful flight the movement of two motors is in clockwise direction and the other two motors move in an anti-clockwise direction. This ensures the stability of the motors and effectiveness of the device.

Figure 2.8 (motor rotate direction) [9]

2.3 ESC – Electronic speed controller

Electronic speed controller have the purpose to control the speed of the motors. The electronic speed controller receive the throttle signal from the FC ( Flight Controller) and drives the motors to an optimal speed. A quality ESC ensure a reliable and smooth flight experience of the quadcopter.

When we choose the ESC first thing to look at them is the current rating, which is measured in Ampers. The motors draw current when they spin and if we draw more ampers than our ESC can support it will start to overheat, which means the motors will eventually fail and also the ESC can even end up in flames.

Three things tend to increase the current draw and put more stress on ESC:

Higher motor KV

Larger motor size

Heavier propellers

Another factor is the battery. How much current can draw from the battery. The 5” builds can survive on 20 amp electronic speed controllers because most of 4S (4 cells) lipo battery from 1300-1500mah won’t even put out enough current to burn a 20 amp electronic speed controller.

2.4 FC – Flight controller

The flight control board is the most important component of the quadcopter. Basically is the ‘brain’ of our drone. On this board we have the sensors such as accelerometers and gyroscopes. There are also flight controllers with two more sensors such as barometer and magnetometer. The FC have also the role to receive the user commands and control the motors in order to keep the drone in the air.

Also the FC comes on different sizes for different model of frames.

Table 2.2

Sensors role:

Accelerometer is a compact device designed to measure non-gravitational acceleration.

Gyroscope is a device that uses Earth’s gravity to help determine orientation.

Barometer is used to measure atmospheric pressure.

Magnetometer is used to measures magnetism.

2.4.1 Processor of Flight Controller

Until now the FC are using 4 main types of CPU to choose: F1, F3, F4, F7. For these days it’s recommended to use an F3 or F4 processor, because F1 model is an old one and F7 is still new and need some improvments in time.

Table 2.3

Figure 2.9 (F1 model) [10] Figure 2.10(F3 model) [11] Figure 2.11(F4 model) [12]

2.4.2 Flight Controller Firmware

The FC use different firmware from one model to another and the modern FC firmware normally can be configured using a software computer such as CleanFlight, BetaFlight, RaceFlight.

2.4.3 Universal Asynchronous Receiver/Transmitter (UART)

UART is the serial port from the hardware that allows us to connect external devices ( Radio receivers, VTX control, Telemetry) to the flight controller.Each UART from the flight controller has two pins on board, one of them is TX for transmitting data/signal and RX for receiving data/signal.

The number of UART on an flight controller depends on design of the flight controller and the processor used on the board.

Table 2.4

2.4.4 Voltage Regulator

The majority of Flight Controllers provides regulated 5V (some FC provides also 9V,12V or other voltages).These voltage regulators are named “BEC” which means battery eliminator circuit.

2.4.5 Boot button

The boot button from the flight controller can put the board into bootloader mode when we use the boot button. This button or pads in some versions of flight controllers allows us to flash firmware I case the normal firmware flash doesn’t work.

Figure 2.12(Left side-boot button | Right side-boot pads) [13]

2.5 Power Distribution Board

The power distribution board have the purpose to power on all the components of the quadcopter so on this board we connect the ESC, FCB, battery, video transmitter, radio receiver, camera, etc.

The PDB has positive and negative pads or terminals which are all connected.When we solder all of the positive wires from the ESC and the battery to the positive pads and the negative wires to all the negative pads, they will become all connected so the battery can provide power supply to all ESC’s. This case is available when we use for the build an ESC for each motor. In the other case when we use 4 in 1 ESC board (all the four motors are connected in a single board) we can connect the ESC directly to the battery pads where we plug in the battery in the PDB.

On the market we can find two types of PDB: integrated and stand alone PDB’s. Some quadcopter frames has a power distribution board integrated into the frame which allows us to solder the battery and ESC’s connectors directly on the frame.

Figure 2.13(Integrated PDB) [15] Figure 2.14(Stand alone PDB) [16]

PDB it’s a basic circuit board that connects all the ground connectors to one and all the positive connectors together allowing us to power on all the components that we mount on the quadcopter.

2.5.1 Voltage Regulator

On the market some PDB’s include a voltage regulator, also known as BEC (like Flight Controllers) that regulate the voltage to a specific value, 5V or 12V. So if we use a 4S battery which have 14.8V output the voltage regulator will convert this voltage and offer us a constant output of 5V or 12V for quadcopter equipment.

2.6 Radio Transmitter and Receiver

The radio transmitter and receiver should be the first components to buy when we want to build an quadcopter and we should look out at: price, modes, frequency and the number of channels.

A radio transmitter (TX) is a device that allows us to control the quadcopter wirelessly and the radio receiver (RX) receive the signal/commands from the radio transmitter .

Figure 2.15 (Radio Transmitter) [17]

2.6.1 Channels

Channels can be considered also as “the number of controls”. The number of channels determines how many individual AUX functions and control we can use and configure in the transmitter.

To control a quadcopter we need a minimum of 4 channels.For example the basic command for a quadcopter are: throttle, yaw ( rotate the quadcopter right and left), pitch ( lean forward and backward), roll ( roll the quadcopter left and right) , each of them use 1 channel.

For other configurations like arm the quadcopter or flight modes we need extra channels. These additional channels on a transmitter are called AUX channels in the form of switches . These switches are used to arm the quadcopter ( turn on the motors ) or to change the flight modes. In generally the most used transmitters are the models that have at least 5 or 6 channels.

2.6.2 Modes

On the market are 4 different transmitters modes – MODE 1, MODE 2, MODE 3, MODE 4. Each mode has different configuration for the 2 control sticks.

Mode 1 – has the elevator control on the left stick and the throttle on the right stick

Mode 2 – the most used because the stick represents the movement of the quadcopter and the elevator control is on the right stick and the throttle is on the left one. The right stick self centres in the both axis and the left stick self centres in yaw axis ( left and right direction ) and slides in the throttle ( up and down ) axis in order to allow a constant throttle.

Figure 2.16 (Radio Transmitter Mode1 and Mode2) [18]

MODE 3 – it’s the same with Mode 1 except the Aileron and Rudder are swapped.

MODE 4 – it’s the same with Mode 2 except Aileron and Rudder are swapped.

Figure 2.17 (Radio Transmitter Mode3 and Mode4) [19]

2.6.3 Frequency and Technology

The most used and common frequency for Receivers is 2.4 GHz because lower frequencies are available for longer range. The higher frequency have the advantage of smaller antenna which is more portable but the range is shorter than the lower frequency.

The 2.4 GHz system models is a newer technology and it’s become the standard models for radio control.

2.6.4 Radio Receiver

A radio transmitter usually comes with a radio receiver (RX) and it’s important to know that a TX model normally only works with an RX model from the same brand . This becomes an important thing because some brands of receivers are more expensive than others and also the receiver will limits what transmitter can we get, such as availability, size, because we need a compact form to makes them to fit perfect in the quadcopter frame.

Figure 2.18 (Radio receiver) [20]

2.7 PROPELLERS

On the quadcopter are used two motors that spin CW ( clockwise direction) and two motors that spins CCW ( counter-clockwise direction) so for the quadcopter we are also use matching CW and CCW propellers that are required to generate thrust and also having opposing yaw motion.

2.7.1 Propeller size

Proppelers can be found in different pitch and length:

The length of a propeller represent the diameter of a disc when it’s spinning

Pitch represent the travel distance of one single propeller rotation.

Propellers generate thrust when are spinning and they are moving air, so when they spin faster the more air it can be move and thus the more thrust it generates. The multirotor can’t fly in outer space because there is no air so the propellers won’t generate any thrust. To generate more thrust to leads to higher current draw we can increase the propeller length or pitch.

The shape of propellers plays a big and important role in performance of the quadcopter because it’s related to surface area, the most distinctive difference would probably be the tip of propellers: bull nose (BN), hybrid bullnose (HBN) and pointy nose.

Hybrid bullnose has more surface area than pointy nose propellers, while the bull nose one has even more surface area than HBN model of propellers.

Th shape of them also changes how the propellers interacts with airflow when are spinning and in generally the smooth/round edges propellers perform more efficiently than blunt/square propellers.

2.7.2 Number of blades

For quadcopters the 3-blade ( tri-blade) propellers are equally popular as the 2-blade (two-blade) propellers. They are commonly used in both: freestyle and racing flying. Basically by adding more blade it’s effectively adding more surface area and generates more thrust.

Figure 2.19 (2-blade propeller) [21] Figure 2.20 (3-blade propeller) [22]

2.8 LIPO BATTERY

To get the best experience, flight time and also performance it’s important to know how to choose the best LiPo battery because the LiPo battery power on all the components of quadcopter.

LiPo batteries comes from Lithium Polymer chemistry and these king of batteries have a very high energy density compared to other types and a battery with a such kind of energy density are able to hold more energy compared to another battery of the same wheight. This is the reason thy Lipo batteries are used for quadcopters.

This kind of battery is made from individual cells, each cell consists of some metal and chemicals packaged together to generate the electrical charge. Connecting these cells between them in various ways we are able to make different LiPo batteries witch various voltages and also capacities.

Figure 2.21 (Lipo Battery) [23]

2.8.1 Cells and Voltage

These kind of batteries are made from rectangular cells which are connected together. A cell holds a nominal voltage of 3,6 V. If more cells are connected in series the voltage can increase to 7.2V for 2 cells battery, 11.1V for 3 cells and so on.

On the market place we will see numbers like 3S2P and that means the battery is a 3 cell one ( 3S ) and the cells are connected in series and 2 cell sets connected in parallel (2P) and 6 individual sells in the battery.

2.8.2 Capacity

Capacity of the battery represent how long it can provide energy for the quadcopter, often quoted in mili Amp hours (mAH). The bigger is this number the more capacity it has, but the higher the capacity it is the heavier is the battery.

2.8.3 Discharge rate

Discharge rate is an important specification to check when we buy a LiPo battery. Discharge rate is notated on the batteries witch C ( C rating ) and define how fast you can extract the energy from battery. To check if the discharge rate is ok for the quadcopter we simply multiply the C value. If we buy a battery witch a C rating of 35C and 1300mAh it will have a continuous current output of 35 x 1,3 = 45,5.

2.8.4 Battery Voltage (cell count)

Battery voltage or cell count is an important decision because higher voltage allow the quadcopter motors to produce more power, however the higher voltage batteries are heavier since contain more cells.

2.9 Battery charger

On the market we can buy non-programmable charger which are “plug and charge”. We just needto plug the battery into the charger and it will start to charge the battery, no input from the user is needed. This might seem simple and also economical but these types of chargers are very slow in charging and we can’t change any of the settings and options.

Nowadays chargers are almost all computerized and programmable and allows us to set all sorts of parameters, such as charging current, type of battery and charging period. This types of chargers also show the battery condition, the voltage per cell, how much current has been charged into them and so on. Basically manages the charging process , ensuring the batteries are charged safely and accurately.

The programmable chargers also do clever things like adjusting charging current depending on charger temperature, auto-detecting battery cell counts and voltage level. Some chargers can charge Lipo battery up to 4S, some of them up to 6S or even higher. This depends on what we need now and in the future.

2.9.1 Charge Rate

The charge rate is limited by 2 factors:

Max charging current that lipo battery can take;

Max charging current that the charger can provide.

For better safety, the batteries are often recommended to be charget at 1C and some expensive batteries from these days are advertised to be fast charged, that means it can be charged at 2C or even higher.

To charge at 1C a 3S battery with 2000mAh capacity the charge current should be 1C x 2000mAh = 2000mA = 2A . To charge at 2C, the charge current should be 2 x 2000mA=4A.

The maximum charging rate that the charger can provide is normally provided in the specifications of the product.

2.9.2 Charger Power Output

Lipo Charger Power is measured in Watt (W) which is calculated by multiply the voltage and current ( Volts and Amps). If the charger does not meet the requirments, the battery it would be charged at a lower current.

2.9.3 Charger’s Modes

A lipo battery charger has the following modes:

Balance charge: is the safest and also the most used charging mode where both the main lead and balance lead are plugged into the battery charger, so the voltage of each cell from the battery is monitored and is balanced during and after charging.

Fast charge: the charging process is more faster because the charger doesn’t balance and monitor the voltage cell from the battery, it only looks at the overall voltage and here is a risk of overcharging one or multiple cells of the battery.

Discharge: this charging mode brings down the voltage of the cell ( depends on the charger and it’s settings)

Storage charge: this mode put the battery cell voltage to 3.8V (this is the voltage suitable for long-term storage)

In conclusion a decent charger should have at least: Balance Charge Mode, Discharge Mode and Storage Charge.

2.9.4 Multiple Channels for charging

Most chargers are single channel chargers and multiple channel charger are very powerful because each channel can be used to charge at the same time two or more different batteries in the same time.

Figure 2.22 (Battery charger) [24]

2.10 Video camera

The biggest payoffs of flying a drone is the images we capture during flight that give us a perspective that we can’t get elsewhere. An quadcopter will come with a camera built-in, but for the pilots that want a higher-quality image or the ability to fly without the added weight it makes sense to buy or build a drone without a camera and buy after what they wish.

Figure 2.23 (Video camera) [25]

2.11 Video transmitter

The video transmitter (VTX) it’s an essential part of a FPV configuration. It’s a device that send the video from FPV camera to a video receiver, which can then display the recorded images on a phone,laptop or FPV glasses.

Figure 2.24 (Video transmitter) [26]

Video transmitter (VTX) can use different frequencies, such as 1.2Ghz,2.4Ghz and 5.8 Ghz, but the most popular frequency that pilots are using is 5.8Ghz because:

The antenna is more smaller for these transmitters

5.8Ghz frequency are legal in many countries

2.11.1 Image Quality and VTX

When we speak about quality of the footage, such as contrast,wide dynamic range, colour and sharpness, paying extra money for a high end VTX isn’t going to improve dramatically the image quality.

Figure 2.25 (Image quality) [27]

The 5.8Ghz frequency systems used for FPV are old analogue technology, so don’t expect any HD level video, for a good quality of video we need to use on the quadcopter an HD action camera.

2.11.2 FPV Signal Quality

Here are 3 factors that affects FPV signal quality and give us a better range:

How good is the FPV antenna;

The sensitivity of video receiver

How accurate the video transmitter is at transmitting at the intended frequency

2.11.3 Video transmitter channels

A 5.8Ghz frequency is equal with 5800MHz, but the frequencies that are used in the band actually stretch from 5325MHz to 5945MHz.

This frequency is popular because it’s legal in many countries and the antennas can be made very small.

The channels available in a VTX , used to broadcast the video back to the video receiver. In the 5.8Ghz band for FPV systems, there are over 10 bands and 80 channels available and the video receiver should be compatible with some of these channels in order to work well.

Figure 2.26 (Video transmitter channels) [28]

2.11.4 NTSC vs. PAL

NTSC and PAL video formats are the two main types of fpv video camera format. The video transmitter doesn’t care about video format , because all modern VTX models on the market support both formats automatically.

2.12 Video receiver

The video receiver is a crucial part of the FPV, specially for first person view quadcopters systems that are using a small and simple camera mounted on the front. The video signal from the camera is send via the transmitter to the receiver where is formatted,amplified and broadcasted.

Figure 2.27 (Video receiver) [29]

2.12.1 Singular and Diversity Modules

The simplest video receivers have one receiver module, using a single antenna and for optimal video reception it has been found that using 2 separate receiving modules working together, called diversity the performance is better. In the receivers there are actually two receiver modules, each with their own antenna for use.

2.12.2 Video receiver frequencies

For racing and freestyle drones like FPV quadcopters, the optimal frequency for video transmission is the 5.8GHz band and it must be the same frequency chosen by the video transmitter to work.

In the following picture we can see the typical VRX frequencies for channels:

Figure 2.28 (VRX channels) [30]

3. Components used for my own build

For my diploma project I built a FPV quadcopter using my own configuration for components. In the following table we can see the brand and model of each component I used in build.

Table 3.1

3.1 FRAME

For my build I use Lisam LS-210 210mm Carbon Fiber Frame because it’s all made from fiber carbon and it’s very easy and rigid and have a medium size. Using this frame our boards ( ESC / FCB / PDB ) must have the same size to assembly all of them on the frame and also for this kind of frame it’s recommended to use these types of motors: Brushless Motor (KV2000~2300) ,electronically commutated motors with electric rotor rotation.

Figure 3.1 (Frame)

Table 3.1

3.2 MOTORS

For this type of frame I selected the Racerstar Racing Edition 2205 2300KV 2-4S Brushless Motor. These motors works with 2-4S lipo battery and are also compatible with our frame catch size.

“KV” is the velocity constant, and it commonly translates to “thousand RPM per volt”.

Figure 3.2 (Motors)

Table 3.2

Figure 3.3(Motor performance data) [31]

3.3 Electronic Speed Controller

The ESC model that I use for my build is a Racerstar RS20Ax4 V2 20A, which is a 4 in 1 model(four esc in a single board). That means all the four motors are connected to this ESC.

Figure 3.4(ESC) [32]

Table 3.3

3.4 Flight Controller

The flight controller board that I used is F3 Flight Controller . In this moment on the market we find FCB that have an F1, F3, F4 and F7 type of processors. It’s recommended to use an F3 or F4 processor for now becausee F1 is an old one and the F7 it’s still new and need some time to be improved.

F3 Flight Controller works with an F3 processor, fits perfect with the frame and also is compatible with CleanFlight for software configuration and the flash memory is enough to store the flight logs and also the CPU is working in best conditions for letting us to ARM the quadcopter ( that means we can turn on the motors ) .

Figure 3.5 (F3 Flight Controller) [33]

Table 3.4

3.5 Power Distribution Board

In my case I use Matek Systems PDB-XT60 that is compatible with 3S-4S lipo battery , fits on the frame and also have a voltage circuit where we can connect the video camera , video transmitter, flight controller, etc.

Figure 3.6 ( Matek Systems PDB) [34]

Table 3.5

3.6 Radio transmitter and receiver

For my build I use FlySky FS-i6 2.4G 6CH AFHDS RC Transmitter With FS-iA6 Receiver. The both components are using 6 channels, that means we can set up 2 AUX channels, one for flight modes and another AUX to arm the quadcopter motors.

Figure 3.7 ( Radio transmitter) [35] Figure 3.8 ( Radio receiver) [36]

Figure 3.9 ( Radio transmitter presentation) [37]

Table 3.6 (FS-i6 Specifications)

Table 3.7 (FS-iA6 Specifications)

3.7 Propellers

For my build I use four propellers that fit on our frame/motors and for a good airflow I use triblade propellers .

Figure 3.10 ( Propellers) [38]

Table 3.8

3.8 Lipo Battery

The battery used in my build is the 4S lipo battery TATTU and I choose this battery because gives the motors more power in flight time because provides a high voltage value 14.8V

Figure 3.11 ( Lipo battery) [39]

Table 3.9

3.9 Battery charger

I use a WLtoys V950 RC Helicopter Part DC 2-4S Battery Charger. This charger works with 2-4S batteries, having an input slot for each model of battery.

Figure 3.12 ( Battery charger) [40]

Table 3.10

3.10 Video camera

For my build I buy Eachine 1000TVL 1/3 CCD 110 Degree 2.8mm Lens Wide. This camera have a switch between PAL and NTSC video format. For PAL we have a 976H X 582V resolution and for NTSC 976H X 494V resolution .

Figure 3.13 ( Video camera) [41]

Table 3.11

3.11 Video transmitter

I use Eachine VTX03 Super Mini with a 5.8Ghz frequency and 72 channels.

Figure 3.14 (Video transmitter) [42]

Table 3.12

3.12 Video receiver

I use Eachine ROTG01 UVC OTG with a 5.8G frequency and 150 channels. This module help us to receive the video transmitted by the video transmitter . In my case I buy a module that is compatible with Android and also Windows operating system. This module receive the 5.8 Ghz signal and via a mobile application i can see in my flight time the video recorded in real time .

Figure 3.15 (Video receiver) [43]

Table 3.13

4. Build process

4.1 Step1 – mounting the frame

The fiber carbon frame comes in parts and it needs to be assembled. The bottom and top fuselage uses 3MM pure carbon fiber board, fuselage and arms in one make the space bigger and make it stronger.

Figure 4.1(mounting the frame) Figure 4.2(frame mounted)

4.2 Step2 – mounting the motors

After we assemble the frame, we need to mount each motor on the arm frame. The motors are fixed on the arms using 4 screws for each motor.

Figure 4.3 (motors) Figure 4.4 ( motors fixed on frame)

4.3 Step3 – placing the electronic speed controller

In this step we place the electronic speed controller in the frame module, then we connect the motors to ESC. Each motor has 3 wires, one for positive,one for ground and the third one is for signal.

Figure 4.5( ESC mounted)

On the ESC board we can see the A1-B1-C1 for motor one, A2-B2-C2 for motor two, A3-B3-C3 for motor three and A4-B2-C4 for motor four. A pin is for the signal wire, B pin is for positive wire and C pin is for negative wire. The RED and BLACK wires are used to power the board, connecting them directly to Lipo Battery , in my case soldering them under the XT60 connector pins from the Power Distribution Board. The GREEN, YELLOW, ORANGE and PURPLE represent the motor’s signals which goes to be soldered on Flight Controller.

4.4 Step 4 – mounting the power distribution board

After we mount the electronic speed controller and solder all the motor wires correctly, we place the power distribution board above the ESC, we solder the red and black wires of ESC directly under the XT60 connector from power distribution board.

Figure 4.6 ( PDB mounted)

In the picture we can see the power distribution board placed above the ESC. In left side the YELLOW connector is the XT60 connector for our battery and under the connector we can see the two wires from the ESC connected directly to battery voltage (power supply wires).

4.5 Step5 – mounting the video camera and video transmitter

Now we place the video camera in front of the frame and video transmitter in back of the quadcopter and connect them to the power distribution board.

Figure 4.7 ( video camera and video transmitter mounted on the frame)

Camera is placed in front of the frame. In picture we can see that my camera model has 3 wires: RED,BLACK and WHITE. The red wire is connected at 5V on the PDB, the black wire is connected to the ground on PDB and white wire is the video signal which is connected with the yellow wire of the video transmitter.

Video transmitter is placed on the back side of the frame. This component has also 3 wires: RED,BLACK and YELLOW. The red wire is connected also at 5V on PDB, black wire goes to ground on PDB and yellow wire is connected with the white wire of the video camera.

The following picture show the final process of this step(in picture is an extra red wire which is from the flight controller, also connected at 5V):

Figure 4.8 (connections on PDB)

4.6 Step6 – mounting the flight controller

After we successfully done these steps we place the next board which is the Fligh Controller.

Figure 4.9 (Flight Controller)

In the picture we can see the flight controller mounted on the frame. The two wires near the XT60 connector (red and black wires) power the flight controller. This wires are connected to 5V and ground on power distribution board.

Under them we can see a solder holes numbered from 1 to 8. Here we connect the motors respecting the order numbered , 1 for motor one, 2 for motor 2 and so on. On left and right side of flight controller we have the IO1 and IO2 (input-output) interface.

These wires goes in the radio receiver, representing the signals for CH1,CH2,CH3,CH4,CH5 and CH6 and also we have the power supply for receiver.

In the next picture we can see the filght controller ports and uses.

Figure 4.10 ( Flight Controller)

4.7 Step7 – mount the radio receiver and final look

After we connect all the pieces together , we connect the receiver to flight controller IO ports in correct order for channels and AUX channels, then we mount the top plate of the frame. After that we can mount the propellers on the motors.

The propellers and motors has 2 directions : CW(clockwise) and CCW(counter clockwise). We must respect the direction in order to have a successful flight.

After we do that the drone should look like this:

Figure 4.11 ( FPV Quadcopter)

4.8 Step8 – connect the quadcopter to Cleanflight

After we build the hardware part , it’s time for final step to get ready the quadcopter for a flight. In my case I use the CleanFlight configurator.

CleanFlight is an app that help us to configure our quadcopter in a easy way. Cleanflight supports a variety model of flight controllers and it’s an open-source flight controller software. With this app we can calibrate our drone, configure the motor speed spin, angle of inclination , rotation , controller sensitivity and more other things like GPS module, etc.

Figure 4.12 ( Cleanflight configurator)

To use this software, firstly we must to install some drivers on our operating system in order to connect the quadcopter with this software.

The following drivers must to be installed:

CP210x driver

STM USB VCP driver

Zading for Windows DFU flashing

If we install these drivers we can connect now the drone.

One end of the cable goes into the USB interface of the operating system and the other side goes into the Micro USB port of the flight controller. Then we press the CONNECT button placed up in the right side of Cleanflight app.

Figure 4.13 ( Connecting Flight Controller to CleanFlight)

After we are connected to the Cleanflight configurator the next windows will appear.

Figure 4.14 ( Main page of CleanFlight – Setup)

First thing we do now is to Calibrate Accelerometer and for that we need to press the button to calibrate. This is a sensor chip that can detect the acceleration of our quadcopter in the roll, pitch or yaw axis and also can detect the constant acceleration of gravity.

4.9 Step9 – Ports tab

Figure 4.15 ( CleanFlight – Ports)

On the ports tab we can find the UART slot that we plugged for our RX, we enable that port and we turn off other switched on that slot. In my case I use UART1. For F1 flight controllers here are two UART slots, but in my case are three because I have an F3 flight controller.

4.10 Step10 – Configuration tab

Figure 4.16 ( CleanFlight – Configuration)

Here we select the model of qadcopter we build Quad X drone and we choose from ESC/Motor Features the ONESHOT125. This is a faster ESC protocol created primarily for mini quadcopters. It uses shorter signal width and Flight Controller board can talk to the ESC/motor much quicker.

Figure 4.17 ( CleanFlight – Configuration – System configuration and Other features)

On the System configuration section we need to check the Accelerometer to enable it and from Other features section the Telemetry.

Accelerometer is the device that measures the proper acceleration and telemetry is the automatic measurement and wireless transmission of data from remote sources.

Figure 4.18 ( CleanFlight – Configuration – Receiver)

On the receiver section we select PWM RX input because our model of receiver has its own single wire, in our case we have 6 channel receiver and we need to connect 6 wires to read the inputs into the flight controller.

PWM is the Pulse Width Modulation wich has been around for a long time in the radio control and is the protocol that our ESC and servo talk to each other on.

4.11 Step11 – Receiver tab

Figure 4.19 ( CleanFlight – Receiver)

Here we can check if our channels works and also we can make a configuration for Stick Low, Stick Center and Stick High, how many rotations we want from the motors when we have the stick from radio transmitter on low, center and high position.

4.12 Step12 – Modes tab

Figure 4.20 ( CleanFlight –Modes)

The flight modes have the role to assists the pilot with flying the drone. Here I use the following modes:

Angle Mode:

Remains level without stick input

Pitch and roll is limited to a particular angle and the drone will not flip

Horizon Mode:

Remains level without stick input

Pitch and roll is not fully limited and the drone will allow for flips

Air Mode:

Makes the quadcopter to think that the drone is flying all the time. PID effect does never get damped out with low throttle, so that also means that it thinks it is flying even when on ground, 0 throttle isn’t anymore a non flying situation.

Acro Mode:

Requires stick input to manually return the drone to level

Pitch and roll inputs determine how fast the drone will rotate on the axis

4.13 Step13 – Motors tab

Figure 4.21 ( CleanFlight –Motors)

In this section we will verify that the motor placement is correct. Here we check the Arm motors configuration box in the right down section. Now we can spin up each motor one at a time by sliding the progress bar in the left down section.

Here we also can calibrate the ESC, Electronic Speed Controller. We check the box “I understand the risks” and we move the master slider all the way to the top and this will send the maximum throttle signal to all motors, four in our case. Now we can connect the battery and when the Electronic Speed Controller will receive max throttle signal at power up, they will enter calibration mode and our motors will beep for a few seconds to indicate this process.

4.14 Step14 – Blackbox tab

Figure 4.22 ( CleanFlight –Blackbox)

Blackbox in cleanflight is useful for diagnose any performance related issue on the quadcopter. All the data are saved on the Dataflash storage. Here we select Onboard Flash because our flight controller has an integrated blackbox and we select 500Hz blackbox logging rate because an F3 flight controller typically will not be able to run over 2kHZ unless our log rate is 500 Hz or lower.

4. Conclusion

This was for me a challenging project to build a quadcopter because I was a beginner in drone area, but after I did a lot of research about every part of a quadcopter and how to build from scratch a drone I’m happy with the result and I will continue with this type of project in the future because it was an interesting experience for me to understand how a drone works.

As airplanes did before, drones are forcing us to reconsider the question of who owns the air. Drones as observers in the sky will remain important for the indefinite future. These will grow easier to operate, the easy of flying and taking pictures can mask the fact that questions concerning how to use those pictures will not get any easier with higher sensor resolutions, cheaper memory and also better lenses.

All of this means that the quantity of informations drones can collect has the capacity to grow quickly than the human ability to take it all in.

I also hope that this paper will serve as a guide to any beginner that want to learn how it’s work and build a drone.

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