Cách chế tạo UAV drone máy bay không người lái how to make a drone

Vì bạn đang tìm kiếm để có được các máy bay không người lái UAV. Loạt hướng dẫn này được thiết kế để giúp bạn hiểu được lĩnh vực đang nổi lên của UAV và hướng dẫn bạn qua quy trình tự xây dựng UAV sử dụng các phụ kiện có sẵn. Thuật ngữ và các định nghĩa sử dụng ở đây nhằm cung cấp cho bạn, người đọc một sự hiểu biết của mỗi thuật ngữ không phải là định nghĩa từ điển. Mặc dù một vài từ có thể có nhiều nghĩa, định nghĩa được sử dụng trong văn bản của UAVDrone

Cách thức chế tạo một Máy bay không người lái (Drone/UAV)

Bài 1: Thuật ngữ

How to Make a Drone / UAV – Lesson 1: Terminology

Posted on October 29, 2014 by Coleman Benson & filed under How to Make a UAV / Drone

How to Make a Drone / UAV – Lesson 1: Terminology

How to Make a Drone / UAV – Lesson 2: The Platform

How to Make a Drone / UAV – Lesson 3: Propulsion

How to Make a Drone / UAV – Lesson 4: Choose a flight controller

How to Make a Drone / UAV – Lesson 5: Assembly

How to Make a Drone / UAV – Lesson 6: Get it all working together

How to Make a Drone / UAV – Lesson 7: FPV & Long-range

Vì bạn đang tìm kiếm để có được các máy bay không người lái UAV Loạt hướng dẫn này được thiết kế để giúp bạn hiểu được lĩnh vực đang nổi lên của UAV và hướng dẫn bạn qua quy trình tự xây dựng UAV sử dụng các phụ kiện có sẵn Thuật ngữ và các định nghĩa sử dụng ở đây nhằm cung cấp cho bạn, người đọc một sự hiểu biết của mỗi thuật ngữ không phải là định nghĩa từ điển Mặc dù một vài từ có thể có nhiều nghĩa, định nghĩa được sử dụng trong văn bản của UAV/Drone

So you’re looking to get into drones and UAVs? This tutorial series is designed to help you understand the emerging field of UAVs and guide you through the process of building your own UAV using off-the shelf parts The terminology and definitions used here are intended to give you, the reader an understanding of each term rather than a dictionary definition Although many words may have multiple meanings, the definition is used in the context of UAVs / Drones

Thuật ngữ / Terminology

Các kiểu UAV / Types

ARF

"Hầu như đã sẵn sàng để bay": một UAV đi kèm lắp ráp với gần như tất cả các

phần cần thiết để bay Các thành phần như bộ điều khiển và bộ tiếp nhận có thể không được bao gồm

“Almost Ready to Fly“: a UAV which comes assembled with almost all parts

necessary to fly Components like the controller and receiver may not be included

BNF

“ Ghép nối và bay”: một UAV được lắp ráp đầy đủ và bao gồm một bộ nhận Bạn chỉ cần chọn một bộ truyền phát tương thích và “ghép” nó với bộ nhận/thu

“Bind and Fly“: the UAV comes fully assembled and includes a receiver You only

need to choose a compatible transmitter and “bind” it to the receiver

DIY

“Tự làm”, được sử dụng với nghĩa “làm theo ý khách hàng” Điều này thường liên

quan đến việc sử dụng các bộ phận từ nhiều nhà cung cấp khác nhau và tạo ra hoặc sửa đổi các bộ phận

“Do It Yourself“, which is now commonly used to mean “custom” This normally

involves using parts from a variety of different suppliers and creating or modifying parts

Drone

Từ này đồng nghĩa với UAV Thuật ngữ “drone” dường như được sử dụng thông dụng hơn trong quân đội, còn “UAV” được sử dụng thông dụng cho sở thích sử dụng

This is synonymous with UAV The term “drone” seems to be more common for military use whereas “UAV” is more common for hobby use

Hexacopter

Một UAV có sáu mô tơ / cánh quạt

A UAV which has six motors / propellers

Multirotor

Nghĩa là một chiếc máy bay có nhiều rô to

“Multirotor” simply means an aircraft with multiple rotors

Octocopter

Một UAV có 8 mô tơ / cánh quạt

A UAV which has eight motors / propellers

Quadcopter

Một UAV có 4 mô tơ / cánh quạt và 4 cánh tay hỗ trợ Các cấu hình là thông thường

có dạng như dấu “+” (phía trước của UAV đối diện một cánh tay) hoặc có khung dấu “X” (phía trước của máy bay đối diện giữa hai cánh tay)

A UAV which has four motors / propellers and four support arms Configurations are normally “+” (the front of the UAV faces one of the arms) or “X” (the front of the aircraft faces between two arms)

RTF

"Sẵn sàng để bay": một UAV mà đi kèm việc lắp ráp hoàn chỉnh với tất cả các bộ

phận cần thiết Đơn giản chỉ cần sạc pin và bay!

“Ready To Fly“: a UAV which comes fully assembled with all necessary parts

Simply charge the battery and fly!

Size (mm)

“Kích cỡ” thông thường được đưa ra dạng mm (vd 450mm) và đại diện cho các điểm lớn nhất đối với khoảng cách điểm giữa hai động cơ trên một UAV Kích thước cũng có thể xác định "loại" của UAV (micro, mini vv)

“Size” is normally provided in millimeters (ex 450mm) and represents the greatest point to point distance between two motors on a UAV Size can also determine the

“class” of UAV ( micro, mini etc)

A UAV which has three motors / propellers, and usually three support arms

UAV

“Phương tiện trên không không người lái” (của một vài kiểu)

“Unmanned Aerial Vehicle” (of any kind)

V-Tail

Một UAV có bốn cánh tay, phía sau hai cánh tay là ở tại góc dạng chữ “V”

A UAV which has four arms, of which the rear two are at an angle to form a ‘V’

X4 / X8

X4 hay X8 là UAV cấu hình với 4 cánh tay hỗ trợ; Cấu hình X4 có một mô tơ tại cuối mỗi cánh, trong khi X8 có hai mô tơ mỗi cánh tay (một mặt trên, mặt còn lại ở phía dưới)

X4 and X8 are UAV configurations with four support arms; X4 configurations have one motor at the end of each arm, whereas X8 have two motors per arm (one facing

up, the other facing down)

Y3 / Y6

Y3 và Y6 là cấu hình UAV với 3 cánh tay hỗ trợ; Y3 cấu hình có một mô tơ tại cuối mỗi cánh tay, trong khi Y6 có hai mô tơ mỗi cánh tay (một mặt trên, mặt còn lại ở phía dưới)

Y3 and Y6 are UAV configurations with three support arms; Y3 configurations have one motor at the end of each arm, whereas Y6 have two motors per arm (one facing up, the other facing down)

Bốn cánh tay / Quadcopter Đuôi chữ V/V-Tail Khung 8 cánh tay / Octocopter Frame

Cơ học / Mechanics

CG

“Tâm trọng lực” đây là điểm trên máy bay tại đó khối lượng cân bằng phân phối

trên tất cả các mặt

“Center of Gravity“; this is the point on the aircraft where there is equal weight

distributed on all sides

pin là Deans & XT60, trong khi kết nối với bộ điều khiển bay và các cảm biến là khoảng cách đều nhau 0,1 "

In order to plug and unplug wires, connectors are used at the ends of wires

Common connectors for batteries are Deans & XT60, while connectors for the flight controller and sensors are 0.1″ spaced

Dampeners

Các phụ kiện cao su đúc được sử dụng để giảm thiểu rung động truyền tới UAV These are molded rubber parts used to minimize vibration transmitted throughout a UAV

Frame

Khung giống như “bộ xương” của máy bay và giữ tất cả các phần phụ kiện trên cùng với nó Các khung đơn giản có các mô tơ kết nối tới cánh tay nhôm hoặc các cánh ép đùn nhẹ khác sau đó kết nối đến một tâm của máy bay

The frame is like the “skeleton” of the aircraft and holds all of the parts together Simple frames have motors connected to aluminum or other lightweight extrusions (“arm”) which then connect to a central body

Multirotor landing gear normally does not have wheels as you might find on an airplane – this is to prevent it from moving when on the ground and reduce overall weight

LED

“Đi ốt phát sáng” Các đi ốt này được sử dụng để tạo quan sát UAV, chủ yếu vào

ban đêm hoặc khi điều kiện ánh sáng yếu

“Light Emitting Diode“ These are used to make the UAV visible, primarily at night

or low lighting conditions

Prop

Guards

“Bảo vệ cánh quạt” Là vật liệu bao quanh một cánh quạt để ngăn chặn các cánh quạt từ liên lạc với các đối tượng khác Chúng được thực hiện như là một tính năng

an toàn và là một cách để giảm thiểu thiệt hại cho UAV

“Propeller guards” are material which curround a propeller to prevent the propeller from contacting other objects They are implemented as a safety feature and a way

to minimize damage to the UAV

Retract

"Có thể thu vào" thường dùng để chỉ càng hạ cánh trong đó có hai vị trí: một để hạ cánh và cất cánh, và mặt khác, trong đó có tác dụng chiếm ít không gian hoặc để cải thiện tầm nhìn, trong suốt chuyến bay

“Retractable” normally refers to landing gear which has two positions: one for landing and takeoff, and another, which takes up less room or improves visibility, during flight

Shell

Lớp vỏ - Đây là một từ chỉ chuyên môn mỹ thuật / chức năng che sử dụng để nâng cao sức bền với các yếu tố và đôi khi cải thiện khí động học Một số UAV sản xuất chỉ có một lớp vỏ nhựa cũng đóng vai trò như những "khung"

This is an aesthetic / functional cover used to improve resistance to the elements and sometimes improve aerodynamics Some production UAVs only have a plastic shell which also acts as the “frame”

Bộ giảm rung động Anti-Vibration Dampener

Càng đáp đất đơn giản Simple Landing Gear

Lớp vỏ UAV UAV Shell

Đẩy, động cơ đẩy / Propulsion

BEC

“Mạch xả pin” một bộ điều chỉnh điện áp được xây dựng vào ESC có thể

cung cấp điện áp quy định 5V DC cho bất kỳ thiết bị điện tử nào mà cần nó

“Battery Eliminator Circuit“: a voltage regulator built into the ESC which

can provide regulated 5V DC power to any electronics which need it

CW indicates Clockwise rotation and CCW indicates

Counter-Clockwise rotation On a multi-rotor aircraft, you would normally use pairs

of counter-rotating propellers

ESC “Bộ điều khiển tốc độ điện tử” là thiết bị kết nối tới pin, mô tơ và bộ điều

khiển bay và điều khiển tốc độ tại đó mô tơ quay

“Electronic Speed Controller” is the device which connects to the battery,

motor and flight controller and controls the speed at which the motor rotates

LiPo

“Polime Li thi um” là loại pin thông dụng nhất được sử dugnj trong các máy bay không người lái Drone và UAV bởi vì khối lượng nhẹ (so với dung lượng lưu trữ) và tốc độ nạp dòng cao

Có các loại pin Lithium- trên thị trường như (LiFe, LiMn, LiOn,…)

“Lithium Polymer” is the most common battery used in drones and UAVs

because of its light weight (versus storage capacity) and high current discharge rates

There are other types of Lithium-based batteries available on the market as well (LiFe, LiMn, LiOn etc)

Motor

Động cơ được sử dụng để xoay cánh quạt; trong UAV loại nhỏ, một động cơ

“chổi quét” thường được sử dụng nhiều nhất, trong khi đó đối UAV lớn hơn, một động cơ "không chổi than" là phổ biến hơn nhiều

The motor is what is used to rotate the propellers; in small UAVs,

a brushed motor is most often used, whereas for larger UAVs, a “ brushless ” motor is much more common

PCB

Một “ Bo mạch in” là phần sợi thủy tinh phẳng với nhiều thành phần hàn

vào nó Nhiều sản phẩm điện tử có một PCB

A “Printed Circuit Board” is the flat fiberglass part with many components

soldered to it Many electronic products have a PCB

Power Distribution

Phân phối nguồn

Để cấp điện cho nhiều thiết bị khác nhau được sử dụng trong một UAV, pin phải được phân chia, là nơi mà các phân phối điện (bảng hoặc cáp) đến

Nó có các điểm đấu âm và dương duy nhất của pin và cung cấp nhiều điểm đấu đầu cuối khác nhau / kết nối mà các thiết bị khác (hoạt động ở cùng một điện áp) có thể nhận nguồn điện

In order to power so many different devices used in a UAV, the battery must

be split, which is where the Power Distribution (board or cable) comes into play

It takes the single positive and negative terminals of the battery and provides many different terminals / connection points to which other devices

(operating at the same voltage) can receive power

A device used to connect the propeller to the motor

Prop Saver

Một loại hub trong đó gắn trên động cơ của bạn và thay thế các bộ chuyển đổi cánh quạt Trong sự kiện của một vụ tai nạn, một phần của các trình bảo

vệ cánh quạt bị mất trong một nỗ lực để cứu cánh quạt

A type of hub which mounts on top of your motor and replaces the prop adapter In he event of a crash, a part of the prop saver is lost in an attempt to save the propeller

The “thrust” is the force which a specific motor and propeller can provide (at

a certain voltage) Usually measured in kilograms (Kg) or pounds (Lbs)

Pin LiPo / LiPo Battery

Cánh quạt chiều kim đồng hồ / Ngược chiều KĐH

Instead of (or in addition to) a hand held transmitter, a station (normally in a case or mounted to a tripod) is used to house / integrate the necessary components used to control a UAV

This can include the transmitter, antenna(e), video receiver, monitor, battery,

computer and other devices

Binding

Thuật ngữ "ghép cặp" đề cập đến cấu hình một bộ truyền phát cầm tay để nó

có thể giao tiếp với một bộ máy thu; nếu một máy phát đi kèm với một bộ tiếp nhận, nó nên được thực hiện tại nhà máy

The term “binding” refers to configuring a handheld transmitter so it can communicate with a receiver; if a transmitter came with a receiver, it should have been done at the factory

Các "bộ điều khiển bay" là những thứ được coi như là "bộ não" của một UAV

và xử lý tất cả các dữ liệu xử lý, tính toán và tín hiệu

Cốt lõi của một bộ điều khiển chuyến bay thường là một lập trình "vi điều khiển" Bộ điều khiển chuyến bay có thể có nhiều cảm biến trên bo, trong đó

có một gia tốc, con quay hồi chuyển, khí áp kế, la bàn, GPS, vv Nếu bộ điều khiển chuyến bay có khả năng điều khiển máy bay riêng của mình (ví dụ như để di chuyển đến tọa độ GPS cụ thể), nó có thể được coi là một "máy bay tự động"

The “Flight Controller” is what would be considered the “brain” of a UAV and handles all of the data processing, calculations and signals

The core of a flight controller is often a programmable “microcontroller” The flight controller may have multiple sensors onboard, including an

accelerometer, gyroscope, barometer, compass, GPS etc

If the flight controller has the ability to control the aircraft on its own (for example to navigate to specific GPS coordinates), it may be considered to be

an “autopilot”

Harness

Điều này thường dùng để chỉ "Bộ dây an toàn", mà các dây dẫn kết nối bộ thu

để điều khiển máy bay (và các thiết bị khác)

This usually refers to the “Wiring Harness” which are the wires that connect the receiver to the flight controller (and sometimes other devices)

HF/ UHF / VHF

"Tần số cao"; "Tần số rất cao" và "Tần số Siêu cao" sóng vô tuyến Đơn vị là

Hz (Hertz)

“High Frequency“; “Very High Frequency” and “Ultra High Frequency”

radio waves Units are in Hz (Hertz)

"quá trình xử lý, suy nghĩ") This is the program which is uploaded to your UAV’s flight controller (similar to a “thought process”)

Bộ điều khiển bay / Flight Controller

Các cảm biến / Định hướng / Sensors / Orientation

Accelerometer

Một cảm biến gia tốc đo gia tốc tuyến tính trong một đến ba trục Bộ phận này thông thường trong ký tự ‘g’ hoặc trọng lực Một cảm biến gia tốc có thể cung cấp cho máy bay không người lái định hướng với liên quan đến mặt đất

An accelerometer measures linear acceleration in one to three axes Units are normally in ‘g’ or gravity An accelerometer can provide your drone’s orientation with respect to ground

Một khí áp kế được sử dụng để đưa ra phản hồi như độ cao của UAV Nó đo

áp lực, và kể từ khi thay đổi áp suất theo độ cao, máy bay của bạn có thể

"biết" độ cao của nó

A Barometer is used to give feedback as to the altitude of the UAV It

measures pressure, and since pressure changes with altitude, your aircraft can

“know” its height

"Hệ thống định vị toàn cầu": các vệ tinh quay quanh hành tinh gửi ra tín hiệu

được chọn của các ăng-ten GPS và được gửi đến được xử lý bởi thiết bị nhận GPS để cung cấp tọa độ địa lý

“Global Positioning System“: satellites orbiting the planet send out signals

which are picked up by the GPS antenna and are sent to be processed by the GPS receiver to provide geographic coordinates

"Bộ phận đo Quán tính" kết hợp một gia tốc kế và con quay hồi chuyển

“Inertial Measurement Unit” combines an accerleometer and a gyroscope

Một linh kiện mà đo tốc độ không khí

A device which measures air speed

Roll

Xoay, Cuộn là chuyển động quay của máy bay dọc theo trục từ mũi đến đuôi của nó

Roll is the rotation of the aircraft along the axis from its nose to its tail

độ) với mặt phẳng hình thành giữa các mũi / đuôi và đầu cánh Yaw is the rotation of an aircraft about an axis perpendicular (90 degrees to)

to the plane formed between the nose / tail and wing tips

Xoay / Xoay quanh cánh/ Trệch

Roll / Pitch / Yaw

Cảm biến tốc độ không khí / Airspeed Sensor

Mô đun GPS / GPS Module

Video

FPV

“Hiển thị người đầu tiên” UAV được gắn với một camera và người vận hành có một

chuyển tải hình ảnh trực tiếp hiển thị trên cả hai màn hình hoặc kính thực tế ảo

“First Person View“: The UAV is mounted with a camera and the operator has a live video feed displayed on either a monitor or virtual reality glasses

Gimbal A devices which carries a camera and is normally actuated using either a servo motor or

a brushless DC motor A gimbal is what can stabilize a camera in flight

GoPro The GoPro series of action cameras is widely used for taking and/or transmitting video

LCD “Liquid Crystal Display” is a type of screen / monitor used to display the image received

by the receiver

OSD “On Screen Display” provides text on the monitor / screen which is being sent from the

aircraft (can include altitude, GPS location etc.)

VR “Virtual Reality” glasses or goggles provide the operator with a more “immersive”

experience

2-Axis Gimbal LCD Monitor for FPV VR Glasses

Do you Really Want a Custom UAV?

The choice of UAV depends on how much you want to learn about the field Building a custom UAV can be quite involved as well as dangerous If you would prefer to simply “get in the air” quickly, we’d suggest the following, in increasing order of complexity:

Toy

Multi-rotor toys are becoming increasingly popular Most are small, and can fit in the palm of your hand, though some like the A.R Drone Parrot are larger Toy multi-rotor UAVs are not necessarily easy to fly, but are more resistant to crashes Toys tend to be smaller and integrate the frame into the aesthetic shell

RTF

A “Ready To Fly” kit includes all the parts needed for a complete UAV Parts include the UAV itself (most often pre-assembled and pre-wired), the hand held transmitter, a battery and charger The craft is calibrated and should be able to fly with relative ease These are not however indestructible, and a crash may damage the system to the point where it is simply worth buying a new aircraft rather than attempting to repair it

ARF

An “almost ready to fly” kit is one where the frame, motors and most of the “core” parts are included and fully assembled (or a few parts need to be assembled, largely to help with shipping) Normally an ARF kit requires the addition of a transmitter / receiver and perhaps batteries and charger Other ARF kits do not include the flight controller itself You may need to do some calibration because of the additional parts required We do not suggest a BNF kit as not all transmitters and receivers are compatible with one another

Do you see terms which are missing and would be useful? Feel free to add them in the comments below

How to Make a Drone / UAV – Lesson 2: The Frame

Posted on January 19, 2015 by Coleman Benson & filed under How to Make a UAV / Drone

How to Make a Drone / UAV – Lesson 1: Terminology

How to Make a Drone / UAV – Lesson 2: The Frame

How to Make a Drone / UAV – Lesson 3: Propulsion

How to Make a Drone / UAV – Lesson 4: Choose a flight controller

How to Make a Drone / UAV – Lesson 5: Assembly

How to Make a Drone / UAV – Lesson 6: Get it all working together

How to Make a Drone / UAV – Lesson 7: FPV & Long-range

Now that you have decided to create your own custom or semi-custom multirotor UAV, the first step is to choose the frame You can either create your own, or base the project off a UAV frame kit There are many different types of frames and configurations used to create multi-rotor UAVs This guide covers the common / basic frame types, materials used to construct the frame, as well as design considerations We welcome any feedback you have in the comments section below

UAV Frame Types

Tricopter

Tricopter

 Description: A UAV which has three arms, each connected to one motor The front of the UAV tends to be between two of the arms (Y3) The angle between the arms can vary, but tends to be 120 degrees In order to move, the rear motor normally needs to be able to rotate (using a normal

RC servo motor) in order to counteract the gyroscopic effect of an uneven number of rotors, as well as to change the yaw angle A Y4 is slightly different in that it uses two motors mounted on the rear arm, which takes care of any gyroscopic effects – no servo is therefore needed

 Advantages: Different “look” for a UAV Flies more like an airplane in

forward motion Price is theoretically lowest among those described here since it uses the fewest number of brushless motor (and ESC)

 Disadvantages: Since the copter is not symmetric, the design uses a

normal RC servo to rotate the rear motor and as such, the design is less straightforward than many other multi-rotors The rear arm is more complex since a servo needs to be mounted along the axis Most, though not all flight controllers support this configuration

Quadcopter

Quadcopter

 Description: A “quadcopter” drone which has four arms, each connected

to one motor The front of the UAV tends to be between two arms (x configuration), but can also be along an arm (+ configuration)

 Advantages: Most popular multi-rotor design, simplest construction and

quite versatile In the standard configuration, the arms / motors are symmetric about two axes All flight controllers on the market can work with this multirotor design

 Disadvantages: There is no redundancy, so if there is a failure anywhere in

the system, especially a motor or propeller, the craft is likely going to crash

Hexacopter

Hexacopter

 Description: A “hexacopter” has six arms, each connected to one motor The front of the UAV tends to be between two arms, but can also be along one arm

 Advantages: It is easy to add two additional arms and motors to a

quadcopter design; this increases the total thrust available, meaning the copter can lift more payload Also, should a motor fail, there is still a chance the copter can land rather than crash Hexacopters often use the same motor and support arm, making the system “modular” Almost all flight controllers support this configuration

 Disadvantages: This design uses additional parts, so compared to a

quadcopter which uses a minimum number of parts, the equivalent hexacopter using the same motors and propellers would be more expensive and larger These additional motors and parts add weight to the copter, so in order to get the same flight time as a quadcopter,

Y6

Y6 Hexacopter

 Description: A Y6 design is a type of hexacopter but rather than six arms,

it has three support arms, with a motor connected to either side of the arm (for a total of six motors) Note that the propellers mounted to the underside still project the thrust downward

 Advantages: A Y6 design actually eliminates a support arm (as compared

to a quadcopter), for a total of three This means the copter can lift more payload as compared to a quadcopter, with fewer components than a normal hexacopter A Y6 does not have the same issue as a Y3 as it eliminates the gyro effect using counter-rotating propellers Also, should a motor fail, there is still a chance the copter can land rather than crash

 Disadvantages: This uses additional parts, so compared to a quadcopter

which uses the same components, the equivalent hexacopter would be more expensive Additional motors and parts add weigh to the copter, so

in order to get the same flight time as a quadcopter, the batteryneeds to

be larger (higher capacity) as well The thrust obtained in a Y6 as opposed

to normal hexacopter is slightly lower (based on experience), likely because the thrust from the top propeller is affected by the lower propeller Not all flight controllers support this configuration

Octocopter

Octocopter

 Description: An octocopter has eight arms, each connected to one motor The front of the UAV tends to be between two arms

 Advantages: More motors = more thrust, as well as increased redundancy

 Disadvantages: More motors = higher price and larger battery pack When

you reach this level most users are looking at very heavy payloads such as DSLR cameras and heavy gimbal systems Given the price of these

systems, added redundancy is really important

X8

X8 Octocopter

 Description: An X8 design is still an octocopter, but has four support arms, each with a motor connected to either side of each arm, for a total of 8 motors

 Advantages: More motors = more thrust, as well as increased redundancy

Rather than using fewer yet more powerful motors, octocopters provide added redundancy in the event of a motor failure

 Disadvantages: More motors = higher price and larger battery pack When

you reach this level most users are looking at very heavy payloads such as DSLR cameras and heavy gimbal systems

UAV Size

UAVs come in a variety of different sizes, from “nano” which are smaller than the palm of your hand, to mega, which can only be transported in the bed of a truck Although both very large and very small UAVs may get quite a bit of attention, they are not necessarily the most practical for hobbyists For most users who are getting started in the field, a good size range which offers the most versatility and value is between 350mm to 700mm This measurement represents the diameter of the largest circle which intersects all of the motors Not only do parts for UAVs in this size range come in a variety of different prices, there is by far the greatest selection of products available

Drone Sizes Smaller UAVs are not necessarily less expensive than medium sized ones This is largely due to the fact that the technology and time needed to produce small brushless motors or small brushless motor controllers is the same for small parts or for large ones The prices for the additional electronics such as the flight controller, remote control, camera etc tend not to change at all The frame is normally one of the least expensive parts of

a UAV, so although the frame for a small UAV may be half the price of a larger one, the overall price, with all parts needed, may still be very close

UAV Materials / Construction

Below are the more common materials found in multi-rotor drones This list does not include all possible materials which can be used and should be looked at as a guideline / opinion as to the use of each material to make the frame of a drone Ideally the frame should be rigid with as minimal vibration transmission as

possible

Wood

If you want your frame to be as inexpensive as possible, wood is a great option, and

will greatly reduce build time and additional parts required Wood is fairly rigid

and has been a proven material time and time again Although the aesthetics may

suffer, replacing a broken arm after a crash is relatively easy and “dirt cheap”

Painting the arm helps hide the fact that it’s wood Ensure you use wood which is

straight (no twisting or warping)

Foam

Foam is rarely used as the sole material for the frame and there tends to be some

form of inner skeleton or reinforcement structure Foam can also be used

strategically; as propeller guards, landing gear or even as dampening There are

also many different types of foam, and some variations are considerably stronger

than others Experimentation would be needed

Plastic

Most users can only access and work with plastic sheets (rather than 3D plastic

shapes or objects) Plastic tends to flex and as such is not ideal Used strategically

(such as a cover or landing gear), plastic can be a great option If you are

considering 3D printing the frame, consider the time needed to print the part

(versus buying a plastic frame kit), and how rigid the part will be in the air 3D

printing parts (or the entire frame) has so far been more successful on smaller

quadcopters Using plastic extrusions may also be an option for small and medium

sized drones

Aluminum

Aluminum comes in a variety of shapes and sizes; you can use sheet aluminum for

body plates, or extruded aluminum for the support arms Aluminum may not be as

lightweight as carbon fiber or G10, but the price and durability can be quite

attractive Rather than cracking, aluminum tends to flex Working with aluminum

really only requires a saw and a drill; take the time to find the right cross section

(lightweight and strong), and try to cut out any non-essential material

G10

G10 (variation of fiberglass) is used as a less expensive option than carbon fiber,

though the look and basic properties are almost identical G10 is mostly available

in sheet format and is used largely for top and bottom plates, while tubing in carbon

fiber (as compared to G10) is usually not much more expensive and is often used

for the arms Unlike Carbon Fiber, G10 does not block RF signals

PCB

Printed Circuit Boards are essentially the same as fiberglass, but unlike Fiberglass,

PCBs are always flat Frames <600mm sometimes use PCB material for top and

bottom plates, since the electrical connections integrated into the PCB can reduce

parts (for example the power distribution board is often integrated into the bottom

plate) Small quadcopter frames can be made entirely out of a single PCB and

integrate all of the electronics

Carbon Fiber

Carbon fiber is still the #1 sought-after building material due to its light weight and

high strength The process to manufacturer carbon fiber is still quite manual,

meaning normally only straightforward shapes such as flat sheets and tubes are

mass produced, while more complex 3D shapes are normally “one off” Carbon

fiber impedes RF signals, so be sure to take this into consideration when mounting

electronics (especially antennas)

Additional Considerations

Gimbal

Gimbal

direction as the frame itself, which does not provide the best video experience Most gimbals are mounted beneath the frame, in line with the UAV’s center of weight Gimbals are either connected directly to the bottom

of a UAV, or to a rail system The gimbal system therefore means the UAV needs longer landing gear so it does not touch the ground Mounting the gimbal or camera to the front of the UAV can also be done, and the weight can

be offset by placing the main battery further aft in the aircraft

Payload

Payload

Adding a “transportation” payload to a drone is still a bit of a luxury, as any added weight reduces flight time and reduces the other items you may wish to add as part of the key features If you really plan to have a payload, ensure that the mounting is as lightweight as possible (while still being secure) and that the load itself does not shift in flight

Landing Gear

Landing Gear

Landing gear for a UAV helps in many ways, and although some drones land directly on their bottom plate (normally to save weight), using landing gear cane be beneficial in many ways:

 Providing clearance between the bottom of the UAV and a non-flat surface such as grass (or small rocks)

 Providing clearance between the battery pack / gimbal and the ground

 In the event of a hard landing, it’s ideally the landing gear which will break (and be replaced) rather than the frame

 The right landing gear can also provide flotation (lightweight pool noodles etc.)

Mounting

Mounting Considerations

Although a UAV is far simpler to design and build than a normal helicopter, there are still enough parts to think about, and how to mount them should be considered early in the design process Some general points to consider regarding mounting, based largely on experience, include:

 If you plan to create a custom frame, one of the more difficult mounting areas is between the motors and the frame, as the four mounting holes need to be placed / drilled precisely Most motors for 400-600mm frames have the same mounting hole pattern, making it possible to use a frame from one manufacturer, and the motors from another

 The placement of all additional components should ideally be symmetric about one axis, which helps facilitate locating and adjusting the aircraft’s center of mass

 The flight controller should ideally be located at the center of the circle connecting all motors (and as such at the center of mass)

 The flight controller is normally fixed to the frame using standoffs, rubber dampeners or double-sided tape Many companies seem to use similar mounting hole locations for the flight controller (ex 35mm or 45mm square), but there is no “industry standard”

 The battery is heavy enough such that if your center of mass if off by a bit, you can move the battery slightly to adjust it Ensure the battery’s

mounting has a bit of “play”, but still ensures it holds the battery firmly Velcro straps are often used to secure the battery, and consider adding adhesive-backed velcro to the battery and frame as well

Guidelines

Step 1: See what materials and machining processes you have at your disposal

 If you do not have much as far as machining capabilities, are not comfortable with tools, or simply want a more professional frame, then consider purchasing a frame kit

 A decent frame can be made with basic tools and materials, but determining areas where it may be structurally weak, resonate (cause vibration) or may be misaligned take a keen eye and experience

 If you plan to create a custom frame, take into consideration all of the mounting which needs to be done; motors, electronics etc and plan accordingly

Step 2: List all of the additional (non-essential) parts you plan to add

 Additional items might include: one, two or three axis camera gimbal, parachute, onboard mini

 This list of additional / non-essential parts will give you an idea of the size of drone you will need, and add to the total weight calculation (to be done later)

Step 3: Get a rough idea of the size of frame you want

 A larger frame does not necessarily make the drone more capable, and a smaller frame does not mean the drone will be any less expensive

 A drone between 400 and 600mm is suggested for beginners

Step 4: Design, build and test the frame

 If you opted to purchase a frame kit, you should not have much to worry about in regards to durability / rigidity / assembly

 If you chose instead to design and build your own frame, it’s important to test its durability, check the weight and see if it can withstand vibration (minimal flex)

 Consider using a CAD software (many are free such as Google Sketchup) to design the frame and ensure dimensions are correct

Now that you have your frame, you can proceed with the next lesson

How to Make a Drone / UAV – Lesson 3: Propulsion

Posted on March 26, 2015 by Coleman Benson & filed under How to Make a UAV / Drone , Tutorials

How to Make a Drone / UAV – Lesson 1: Terminology

How to Make a Drone / UAV – Lesson 2: The Frame

How to Make a Drone / UAV – Lesson 3: Propulsion

How to Make a Drone / UAV – Lesson 4: Flight controller

How to Make a Drone / UAV – Lesson 5: Assembly

How to Make a Drone / UAV – Lesson 6: Get it all working together

How to Make a Drone / UAV – Lesson 7: FPV & Long-range

Now that you have either chosen or built a frame, the next step is to choose the right propulsion system A complete propulsion system includes motors, propellers, ESCs and a battery Almost all small multi-rotor

drones / UAVs are electric, with almost none being gas-powered For this reason, we will focus on

implementing an electric propulsion using brushless DC motors

1 Motor

The motors you use will have a huge impact on the payload (or maximum load) which your UAV can support,

as well as the flight time We strongly suggest using the same (propulsion) motor everywhere Note that even

if a pair of motors are the same brand and model, and from the same production run, their speeds may vary slightly, which is something the flight controllerwill take care of

Inrunner Motor Brushless DC Motor DC “Pancake” Motor

Brushed vs Brushless

Brushed motors spin the coil inside a case with fixed magnets mounted around the outside of the casing Brushless motors do the opposite; the coils are fixed either to the outer casing or inside the casing while the magnets are spun In most situations, you will be considering only brushless DC motors Brushless DC motors are used extensively in the hobby RC industry for products ranging from helicopters and airplanes to the drive system in RC cars and boats “Pancake” brushless motors have a larger diameter and are essentially flatter and often allow for higher torque and lower KV (details below) Smaller UAVs (usually the size of the palm of your hand) tend to use small brushed motors because of the lower price and simpler two-wire controller Although brushless motors come in a variety of different sizes and specs, selecting a smaller brushless motor rarely means it will be less expensive

Inrunner vs Outrunner

There are a few types of brushless DC motors:

 Inrunner – these have the fixed coils mounted to the outer casing and the magnets are

mounted to the armature shaft which spins inside the casing (tend to be used on RC cars because of the high Kv)

 Outrunner – these have the magnets mounted on the outer casing which is spun around the fixed coils in the center of the motor casing (the bottom mounting of the motor is fixed)

 Hybrid outrunner – technically outrunners but have a static outer shell around them to make them look like they’re inrunners

Inrunner brushless DC motors tend to be used in RC cars, airplanes and helicopters because of their high KV They may also be geared down to increase the torque Outrunners tend to have more torque

“KV”

The KV rating / value of a motor relates to how fast it will rotate for a given voltage For most multirotor aircraft, a low KV is desired (between 500 to 1000 for example) since this helps with stability For acrobatic flight however, you might consider a KV between 1000 and 1500 and also consider using smaller diameter propellers If the KV rating for a particular motor is 650rpm/V, then at 11.1V, the motor will be rotating at 11.1V x 650 = 7215rpm If you operate the motor at a lower voltage (say, 7.4V), the rpm will be 7.4V x 650rpm/V = 4810rpm It is important to note that using a lower voltage tends to mean that the current draw will be higher (power = current x voltage)

a motor + propeller combination which can provide more thrust, or reduce the weight of the aircraft If the propulsion system (all motors and props) can provide 2Kg of thrust (max) then your entire copter should be at most about half this weight (1Kg, including the weight of the motors themselves) The same calculation can be done for any given configuration Let’s assume a hexacopter‘s weight (including frame, motors, electronics, battery, accessories etc) to be 2.5Kg Each motor should therefore be capable of providing (2.5Kg/6 motors) x 2:1 = 0.83kg of thrust (or more) You can now calculate the specs of your motor(s) but suggest reading through the sections below before making a decision

Additional Considerations

 Connectors: Brushed DC motors have two connectors: one for positive, the other for

negative Reversing the wires reverses the rotation of the motor

 Connectors: Brushless DC motors have three connectors Refer to the ESC section below to know how to wire them and reverse direction of rotation

 Windings: The windings impact the KV of a motor When you want a lower KV but

maintain the torque, you may need to consider a larger pancake-style brushless DC motor

 Mounting: Most manufacturers have a general mounting pattern for brushless DC motors which has allowed companies which produce frames to not have to design adapters The pattern is normally metric, with two holes spaced 16mm apart, and another two holes spaced 19mm apart (at 90 degrees to the first)

 Thread: The mounting thread used to secure a brushless motor to a frame can vary Common metric screw sizes include M1, M2 and M3 and imperial might be 2-56 and 4-40

2 Propeller

Propellers for multi-rotor aircraft are adapted from propellers used in RC airplanes Why not use helicopter blades? Although it has been done, imagine the size of a hexacopter which used helicopter blades Note that a helicopter-type system also requires that you vary the pitch of the blades which significantly adds to the mechanical complexity You may also ask why not use a turbojet, turbofan, prop-jet etc? These are incredibly

good at providing a lot of thrust, but also require a lot of power If the objective of the drone was to move really fast rather than hover in confined areas, one of these may be a good option

Propeller

Blades & Diameter

Most multi-rotor aircraft have either two and three rotor blades, with the most common being two Do not assume that adding more blades will automatically mean more thrust; each blade must travel through the wake

of the one which precedes it, so the more blades, the more prevalent the wake will be A smaller

diameter propeller has less inertia and is therefore easier to speed up and slow down, which helps in acrobatic flight

Propeller Diameter

Pitch / Angle of Attack / Efficiency / Thrust

The thrust produced by a propeller depends on the density of the air, on the propeller’s RPM, on its diameter,

on the shape and area of the blades and on its pitch A propeller’s efficiency relates to the angle of attack which is defined as the blade pitch minus the helix angle (the angle between the resultant relative velocity and the blade rotation direction) The efficiency itself is a ratio of the output power to the input power Most well-designed propellers have an efficiency of 80%+ The angle of attack is affected by the relative velocity, so a propeller will have different efficiency at different motor speeds The efficiency is also greatly affected by the leading edge of the propeller blade, and it is very important that it be as smooth as possible Although a variable pitch design would be best, the added complexity required as compared to a multirotor’s inherent simplicity means a variable pitch propeller is almost never used Additional information regarding the theory behind blade design and thrust generated can be found online at sites such as the MDP project There are also several online tools which helpcalculate a propeller’s thrust Certain sites list a variety of motors such

as eCalc for the thrust calculations

Propeller Pitch (one revolution)

Propeller Angle of Attack

Rotation

Propellers are either designed to rotate clockwise (CW) or counter-clockwise (CCW) It is important to know which part of the propeller is intended to face upwards (the top surface is curved outward) If the design of your multirotor inverts some of the motors (as is the case for a Vtail, Y6, X8), be sure to change the orientation

of the propellers so the thrust is still downwards The top of the propeller should always face the sky The

documentation associated with the flight controller (discussed in the next lesson) normally shows you which way each propeller is intended to turn for each multi-rotor it supports

Counter Rotating Propellers

Fiber-Reinforced Polymer

A fiber-reinforced polymer propeller (carbon fiber, nylon reinforced carbon etc.) is “cutting edge” technology

in more ways than one Carbon fiber parts are still not very easy to produce and as such you pay quite a premium for them over a plastic propeller with the same specifications In the event of a crash, a carbon fiber propeller is harder to break and flex and as such will cause more damage to whatever it contacts This having been said, if you want to consider a fiber-reinforced propeller, they are normally well made and rarely require balancing, are stiffer (so fewer losses in efficiency due to flexing etc) and are lighter weight than other

materials We suggest considering these high performance propellers only after you are comfortable flying

Natural

Natural materials such as wood are not used often to make propellers for mulitirotors as they require

machining to produce and therefore cost more than plastic The main advantage heere is that wood is quite strong and will not bend Wood propellers are still used for RC airplanes

Propeller Materials

Folding

Folding propellers have a central part which connects to two pivoting blades When the center (which is connected to the motor’s output shaft) spins, centrifugal forces act on the blades, forcing them outwards and essentially making the propeller “rigid”, with the same effect as a fixed propeller Because of lower demand and higher number of parts required, folding propellers are less common than fixed propellers As expected, a folding propeller makes transporting the aircraft quite a bit easier, and combined with a folding frame, the

“retracted” size of the UAV can be significantly smaller than in flight Folding propellers also have a nice advantage of only having to change one blade in the event of a crash

Folding Propeller

Mounting

Since aerial vehicles can come in a wide range of sizes, so can propellers As such, there are a few somewhat more “standard” sized motor shaft diameters in the industry Propellers often come with a small selection of these adapter rings (which look like washers with various different diameter holes in the middle) to press into a cutout of the propeller so it centers it on the motor’s shaft If you find that the center (“bore”) of the propeller you are using is way too large for the shaft of your motor, you will need the spacer / adapter ring Don’t assume that the propeller you are purchasing includes the adapter; check the bore and compare it to your motor’s shaft diameter

Certain manufacturers further customize the way the propeller mounts to the motor Some have D-shaped (single or double) cutouts on the motor, and the propeller has the missing material; this ensures that the

propeller will not loosen itself in flight Other manufacturers have been known to include other types of specific “male / female” motor to propeller connections as well Newer propellers have a thread rather than a hole which is opposite to that of the rotation, and the motor’s shaft has the same thread, essentially tightening the propeller when rotating

Prop savers

Prop savers replace the normal propeller adapter on a motor and have a small part (such as an O-ring) which keeps the propeller in place In the event of a crash, the propeller is normally prevented from rotating (ex it contacts an object) and since the motor is still rotating and high speeds, it causes the O-ring to either rip apart

of fly off, ideally saving both the motor and the propeller from damage As great as this might be, there are a few disadvantages:

 The propeller sits higher on the shaft

 If the design of the prop saver is off, or not properly centered center it can lead to vibration

 Check O-rings periodically since they may become brittle and crack in flight

Prop guards

Propeller guards (“prop guards”) connect to the main frame and provide a fixed ring / cushion around the propeller Should the UAV contact an object, ideally the propeller guards will contact the object first and withstand the impact so the propellers are not touched Small toy multi-rotor UAVs often have removable plastic prop guards included As always, there are some compromises to using prop guards:

 They can be a high source of vibration

 Only good for low force impacts

 Can lower thrust if there are too many supports directly under the propeller wash

Prop Guard

Balancing

Most inexpensive propellers are not very well balanced, which can be seen by simply balancing the center on a pencil (one side will likely be heavier than the other) As such, it is always good practice to balance your propellers before fixing them to the motors It is very important that the propeller be balanced because if not, the vibrations caused by an unbalanced propeller often propagate to the flight controller, causing erratic flight

A propeller can be balanced many ways, but if you are building your own UAV, then an inexpensive prop balancer is ideal A prop balancer simply allows you to easily see where there is a weight unbalance in the propeller In order to adjust the weight, you can either sand down the heavier part (evenly sand the center part

of the propeller only as opposed to leading or trailing edges, and DO NOT cut off part of the propeller), or add

clear masking tape (which is very thin) to the lighter side (and keep adding lengths of tape evenly until it is balanced) Note that the farther away from the center you make the modification (sanding or adding tape) the more of an effect it will have based on the principle of torque

Propeller Balancer

3 ESC

An ESC (acronym for “Electronic Speed Controller“) is what allows the flight controller (covered in the next lesson) to control the speed and direction of a motor The ESC must be able to handle the maximum current which the motor might consume, and be able to provide it at the right voltage Most ESCs used in the hobby industry only allow the motor to rotate in one direction, though with the right firmware, they can operate in both directions

Brushless ESC

Connectors

An ESC might initially be confusing because it has several wires exiting on two sides

 Power input: The two thick wires (normally black and red) are to obtain power from the power distribution board / harness which itself receives power directly from the main battery

 3 bullet connectors: These pins are what connects to the three pins on the brushless motor There are some standard sizes in the industry, but if you find the two are mismatched, you will need to replace one set

 3-pin R/C servo connector: This connector accepts RC signals, but rather than requiring 5V

on the red and black pins, most of the time an internal BEC provides 5V to power the

electronics

In certain instances, the manufacturer does not want to assume which connectors you are using, and leaves the wires for the motor connection and power input bare (they may provide bullet connectors in the packaging which you may or may not want/need and would have to solder onto the wires) The bullet connectors you received with the motors may also not match those of the ESC, so in this case, it’s simply best to replace one

or the other Your next question is obviously given three bullet connectors, which one plugs into which on the motor? As far as the connector for the power, this is entirely up to you – ideally you would use connectors to make the ESC easily removable in case of failure, or if you want to use it on a different project, but be sure that the positive on the ESC goes to the positive on the battery, and same for negative In order to reverse the direction of rotation, swap any of two of the three connectors between the ESC and the brushless motor

BEC

Most ESCs include what is called a “Battery Elimination Circuit” or BEC This comes from the fact that historically, only one brushless motor was needed in a given RC vehicle, and rather than splitting hte battery, it would just need to be connected to the ESC, and the ESC would have an onboard voltage regulator to power the electronics.It is important to know the current which an ESC’s BEC can provide, though it is normally in the range of 1A or above and is almost always 5V

In a multi-rotor, you need to connect all ESCs to the flight controller, but only one BEC is needed, and having power coming from multiple sources all being fed to the same lines can potentially cause issues Since there is normally no way to deactivate a BEC on an ESC, it is best to remove the red wire and wrap it with electrical tape for all but one ESC It is still important to leave the black (ground) wire in place for “common ground”

Firmware

ESCs are not all equally good for use with multi-rotors It is important to understand that before multi-rotors were around, that brushelss hobby motors were used primarily for RC car drives, airplane propellers and as primary motors in model helicopters Most of these applications did not require very fast response time or rapid updating An ESC equipped with SimonK or bheli firmware is able to react very fast (much higher frequency) to changes in input, which may mean the different between stable flight or a crash

Power Distribution

Since each ESC is powered from the main battery, the main battery’s single connector must somehow be split amongst four ESCs To do so, a power distribution board, or power distribution harness is used This board (or cable) splits the main battery’s positive and negative terminals into four It is important to note the type of connectors used on the battery, ESC and power distribution board may not all be the same, and it is best, whenever possible, to choose a “standard” connector (such as Deans) which is used throughout Many

inexpensive boards require soldering, as they do not want to assume you are using any specific connector A very simply power distributor could involve a two input terminal block or soldering all positive connections together, and then all negative connections together

4 Battery

Chemistry

Batteries used in UAVs are now almost exclusively Lithium polymer (LiPo), with some more exotic ones being Lithium-Manganese or other Lithium variations Lead acid is simply not an option and NiMh / NiCd are still too heavy for their capacity and often cannot provide the high discharge rates needed LiPo offer high capacity with low weight, and high discharge rates The downsides are their comparatively higher cost and continued safety issues

Voltage

You should really only need to consider one battery pack for your UAV This battery’s voltage should

correspond with the motors you chose Almost all batteries used these days are lithium-based and incorporate

a number of 3.7V cells, where 3.7V = 1S Therefore a battery which is marked as 4S is likely 4 x 3.7V = 14.8V nominal Providing the number of cells however will help you determine which charger to use A single cell high capacity battery may physically look a lot like a low capacity multi-cell battery

Capacity

A battery pack’s capacity is measured in amp-hours (Ah) Small battery packs can be in the range of 0.1Ah (100mAh) though battery packs for medium sized drones are 2-3Ah (2000mAh-3000mAh) The higher the capacity, the longer the flight time, but the heavier the pack will be You can expect the flight time of a normal UAV to be in the order of 10-20 minutes, which might not seem like a long time, but you need to consider it’s always fighting against gravity, and unlike an airplane, there are no surfaces to help with lift

Discharge Rate

The discharge rate from a lithium battery is measured in C, where 1C is the capacity of the battery (normally in amp hours unless you’re looking at a very small drone the size of your hand) The discharge rate of most LiPo batteries is at least 5C (five times the capacity), but since most motors used in multirotors consume high current, the battery needs to be able to discharge at incredibly high current, which is often in the order of 30V

or more

Safety

LiPo batteries are not entirely safe since they contain pressurized hydrogen gas and have a tendency to burn and/or explode when there is something wrong As such, if you have any doubts about the battery pack you are holding, DO NOT plug it into the UAV or even the charger – consider it a “write off” and dispose of it

properly Telltale signs that something is wrong include dents or the battery is larger than it was when you first received it (i.e leaking gas) When charging a LiPo battery, it is best to keep it in a LiPo safe bag Storing the battery is also ideally done in a LiPo bag as well In the event of a crash, the first thing you need to do is unplug and check the battery Having the battery in a fully enclosed case may add to the weight, but can really help keep your battery safe in a crash Certain battery manufacturers sell batteries with and without a hard case

Charging

Most LiPo batteries have two connectors: one is intended to be the main “discharge” wires which can handle high current, while the other, normally smaller and shorter one is the charging connector This charging

connector is almost always a white JST connector which has one ground pin following by the same number of cells used to create the pack This is what you connect to the LiPo charger which then takes care of charging (and balancing) each internal cell The charger should indicate when charging is complete and, given the safety issues with LiPo batteries, it is best to unplug the battery and charger when charging is complete

Mounting

The battery pack is the heaviest item on the UAV and as such, should be placed dead center to ensure the motors are subjected to the same load A battery does not include any specific mounting (especially screws which could puncture the LiPo and cause a fire), so some mounting methods currently used involve Velcro straps, rubber, plastic compartment among others Having the battery suspended below the frame using Velcro

is quite popular because of accessibility

LiPo Battery

How to Make a Drone / UAV – Lesson 4: Flight Controller

Posted on May 25, 2015 by Coleman Benson & filed under How to Make a UAV / Drone

How to Make a Drone / UAV – Lesson 1: Terminology

How to Make a Drone / UAV – Lesson 2: The Frame

How to Make a Drone / UAV – Lesson 3: Propulsion

How to Make a Drone / UAV – Lesson 4: Flight Controller

How to Make a Drone / UAV – Lesson 5: Assembly

How to Make a Drone / UAV – Lesson 6: Get it all working together

How to Make a Drone / UAV – Lesson 7: FPV & Long-range

Now that you have chosen or designed a UAV frame, chosen the appropriate motors, propellers, ESCs

and battery, you can start looking into choosing a flight controller A flight controller for a multi-rotor UAV is

an integrated circuit normally made up of a microprocessor, sensors and input / output pins Out of the box, a flight controller does not magically know your specific UAV type or configuration, so you need to set certain parameters in a software program, and once complete, that configuration is then uploaded to board Rather than simply comparing flight controllers which are currently available, the approach we have taken here lists which features serve which functions, as well as aspects to look for

Main Processor

8051 vs AVR vs PIC vs ARM: These microcontroller families form the basis of most current flight

controllers Arduino is AVR based (ATmel) and the community seems to focus on MultiWii as being the preferred code Microchip is the primary manufacturer of PIC chips It is difficult to argue that one is better than the other, and it really comes down to what the software can do ARM (STM32 for example) uses 16/32-

bit architecture, whereas AVR and PIC tens to use 8 / 16-bit (described below) As single board computers become less and less expensive, expect to see a new generation of flight controllers which can run full

operating systems such as Linux or Android

CPU: Normally these are in multiples of 8 (8-bit, 16-bit, 32-bit, 64-bit) and is a reference to the size of the primary registers in a CPU Microprocessors can only process a set (maximum) number of bits in memory at a time The more bits a microcontroller can handle, the more accurate (and faster) the processing will be For example processing a 16-bit variable on an 8-bit processor is a bit of a chose, whereas on a 32-bit processor it

is very fast Note that the code also needs to work with the right number of bits, and at the time of this article, very few programs use code optimized for 32 bits

Microcontroller

Operating frequency: The frequency at which the main processor operates Frequency is measured in “Hertz”

(cycles per second) This is also commonly referred to as the “clock rate” The higher the operating frequency, the faster it can process data

Program Memory / Flash: The flash memory is essentially where the main code is stored If the program is

complex it may take up quite a bit of space Obviously the greater the memory, the more information it can store Memory is also useful when storing in-flight data such as GPS coordinates, flight plans, automated camera movement etc The code loaded to the flash memory remains on the chip even if it power is cut

SRAM: SRAM stands for “Static Random-Access Memory”, and is the space on the chip which is used when

making calculations The data stored in RAM is lost when power is cut The higher the RAM, the more information will be “readily available” for calculations at any given time

EEPROM: Electrically Erasable Programmable Read-Only Memory (EEPROM) is normally used to store

information which does not change in flight, such as settings, unlike data stored in SRAM which can relate to sensor data etc

Additional I/O Pins: Most microcontrollers have a lot of digital and analog input and output pins, and on a

flight controller, some are used by the sensors, others for communication and some may remain for general input and output These additional pins can be connected to RC servos, gimbal systems, buzzers and more

A/D converter: Should the sensors used onboard output analog voltage (normally 0-3.3V or 0-5V), the analog

to digital converter needs to translate these readings into digital data Just like the CPU, the number of bits which can be processed by the A/D determines the maximum accuracy Related to this is the frequency at which the microprocessor can read the data (number of times per second) to try to ensure no information is lost It is nevertheless hard not to lose some data during this conversion, so the higher the A/D conversion, the more accurate the readings will be, but it is important that the processor can handle the rate at which the information is being sent

Power

There are often two voltage ranges described in the spec sheet of a flight controller , the first being the voltage input range

of the flight controller itself (most operate at 5V nominal), and the second being the voltage input range of the main

microprocessor’s logic (ex 3.3V or 5V) Since the flight controller is a fairly integrated unit, you really only need to pay

attention to the input range for the flight controller itself Most multi-rotor aircraft flight controllers operate at 5V since

that is the voltage provided by a BEC (see lesson 3 for more information) To reiterate, you should ideally not power t

flight controller separately from the main battery The one exception is if you want a battery backup in the event that the

main battery draws enough power that the BEC cannot provide enough current / voltage, causing a brownout / reset

Rather than a battery backup however, capacitors are often used

Sensors

In terms of hardware, a flight controller is essentially a normal programmable microcontroller, but has

specific sensors onboard At a bare minimum, a flight controller will include a three axis gyroscope, but as

such will not be able to auto-level Not all flight controllers will include all of the sensors below and may

include a combination thereof The sensors

Accelerometer Axes

Accelerometer

As the name implies, accelerometers measure linear acceleration in up to three axes (let’s call them X, Y and Z) The units are normally in

“gravity” (g) which is 9.81 meters per second per second, or 32 feet per second per second The output of an accelerometer caintegrated twice to give a position, though because of losses in the output, it is subject to “drift” A very important characteristic of three axis accelerometers is that they detect gravity, and as such, can know which direction is “down” This plays a major role in

multirotor aircraft to stay stable The accelerometer should be mounted to the flight controller so that the linear axes line up with the main axes of the UAV

Gyroscope Axes

Gyroscope

A gyroscope measures the rate of angular change in up to three angular axes (let’s call them alpha, beta and gamma)

degrees per second Note that a gyroscope does not measure absolute angles directly, but you can iterate to get the angle which, just like an accelerometer, is subject to drift The output of the actual gyroscope tends to be analog or I2C, but in most cases you do not need to worry about it since this is handled by the flight controller‘s code The gyroscope should be mounted so that its

axes of the UAV

wind over the chip

GPS Satellites

GPS

Global Positioning Systems (GPS) use the signals sent by a number of satellites in orbit around the earth in order to determine their specific geographic location A flight controller can either have onboard GPS or one which is connected to it via a cable The GPS antenna should not be confused with the GPS chip itself, and can look like a small black box or a normal “duck” antenna In order to

accurate GPS lock, the GPS chip should receive data from multiple satellites, and the more the better

Distance

Distance

Distance sensors are being used more and more on drones since GPS coordinates and pressure sensors alone cannot tell you how from the ground you are (think hill, mountain or building) or if you will hit an object A downward-facing distance sensor might be based

on ultrasonic, laser or lidartechnology (infrared has issues in sunlight) Very few flight controllers include distance sensors as part of the standard package

Flight Modes

Below is a list of the most popular flight modes, though not all will be available on all flight controllers A

“flight mode” is the way the flight controller uses sensors and RC input in order to fly and stabilize the aircraft

If you have a transmitter with five or more channels you may be able to configure the software to allow you to

change the flight mode via the 5th channel (aux switch) while in flight Each mode is defined below

Mode Gyroscope Accelerometer Barometer Compass GPS Notes

( drone cannot auto-level) ANGLE

Stable mode; will try to keep the model level to the ground (but not at a fixed position)

acrobatics with fast RC commands.

BARO (Altitude

Barometer is used in order to keep a certain (fixed) height when

no other commands are received.

Proportional Integral Derivate (PID) control allows you to change the drone‘s flight characteristics, including how it reacts to user input,

how well and how quickly it stabilizes and more The PID settings and how the software uses the various sensor inputs are incredi

important, but without seeing and understanding the code which dictates this is not too useful when comparing flight controllers

Manufacturer which produce “ready to fly” kits are able to fine tune the PID settings and equations for their specific platform, which is

why most RTF muti-rotors fly quite well out of the box Builders of custom drones however need to use flight controllers which are

designed to be suitable for almost any type of multi-rotor aircraft, and as such it is up to the end-user to adjust the values until they are

satisfied with the flight characteristics

GUI

A GUI (Graphical User Interface) is what is used to visually edit the code (via a computer) which will be uploaded to the flight controller

The software provided with flight controllers continues to get better and better; the first flight controllers on the market used largely text

based interfaces which required that you understand almost all of the code and change specific sections to suit your project More re

flight controller GUIs use interactive graphical interfaces to help you configure the necessary parameters

Additional Features

The software used on certain flight controllers may have additional features which are not available on others Your selection of a specific

flight controller may ultimately depend on which additional features / fuctionality are offered These features can include:

 Autonomous waypoint navigation, which allows you to set GPS waypoints which the drone will follow autonomously

 “Oribiting” i.e moving around a fixed GPS coordinate with the front of the drone always pointed towards the

coordinate (useful for filming)

 “Follow me”: certain drones have a “follow me” feature which can be GPS based (for example tracking the GPS

coordinates of a smart phone)

 3D imaging: Most 3D imaging is done after a flight using images captured during the flight and GPS data

 “Open source”: the software associated with certain flight controllers cannot be modified / customized Open

products generally allow advanced users to modify the code to suit their specific needs

 Pitch (which translates to forward / backward motion)

 Elevation (closer to or farther away from the ground)

 Yaw (rotating clockwise or counter-clockwise)

 Roll (to strafe left and right) Additional channels can be used for any of the following

 Arming / disarming the motor s

 Gimbal controls (pan up/down, rotate clockwise / counter-clockwise, zoom)

 Change flight modes (acrobatic mode, stable mode etc)

 Activate / deploy a payload, parachute, buzzer or other device

 Any number of other uses

Most drone pilots prefer handheld control, meaning RC systems are still the number one choice for controlling a UAV On its own, the receiver simply relays the values input into the controller, and as such, cannot control a UAV The receiver must be connected to thecontroller, which needs to be programmed to receive RC signals There are very few flight controllers on the market which do