A basic overview of how drones are build and how they work


#1

Since I haven’t been so active in the past few months because of my lack of time, I’m coming back with some new knowledge to spread around. The 0x00sec drone is on the way to be accomplished right? So why not understand how drones generally work and even build your own.

Disclaimer: All the information provided in this article is pure self-researching, so if I got something wrong please let me know. Also some constructive criticism is always welcomed.

What is a drone

According to wikipedia a drone is:

An unmanned aerial vehicle ( UAV ), commonly known as a drone , is an aircraft without a human pilot aboard. UAVs are a component of an unmanned aircraft system (UAS) which include a UAV, a ground-based controller, and a system of communications between the two. The flight of UAVs may operate with various degrees of autonomy: either under remote control by a human operator or autonomously by onboard computers.

Typically an unmanned aircraft is made of light composite materials to reduce weight and increase maneuverability.

There are multiple types of drones. Here are some of them:

Number of Propellers Size Range Equipment
Tricopter Nano Drones Close Range Drones Drones with Camera
Quadcopter Mini Drones Short Range Drones Drones with FPV
Hexacopter Regular Size Drones Mid-Range Drones Drones with GPS
Octocopter Large Drones Endurance Drones Drones with stabilizers

As you can see, they can be categorized by range, size, number of propellers, etc. Of course, there are out there military drones, space drones, etc. But I mainly discuss here about types you can build and are out for the public to buy.

For the next part of the article, I will be talking only about FPV drones that are usually quadcopters.

The anatomy of a drone

In order to start building a drone, you will first need to understand what each component does. I will take each component apart and explain what is its role, but before that, let’s look at a basic overview of a basic FPV drone:

You can think of this as 3 main parts:

  • The FPV system consists of video streaming components such as: camera, FPV goggles and video transmitter.

  • The Flight system is helping the drone to actually fly (Flight Controller, motors, ESC, propeller, etc).

  • The Power system is made of components that distribute electrical power to the other components of the drone in order to make it work (PDB, Battery).

The FPV system

As said earlier, the FPV system consists of a camera, FPV goggles and a video transmitter. Basically the camera mounted on your drone capture a video. This is sent back with the help of the video transmitter by broadcasting a signal wirelessly. This signal is caught by your video receiver, on the goggles, and it’s shown onto the screen.

The flight system

The flight system is composed of the following components: flight controller, R/C controller, R/C receiver, motors, ESCs and propellers. The way it works is the following:

  1. The pilot is moving the joystick on the R/C controller.
  2. That signal is sent to the R/C receiver wirelessly.
  3. The R/C receiver then is forwarding the signal to the flight controller.
  4. The flight controller interprets these commands, calculates what speed each motor should have and send it to the ESCs.
  5. The ESCs are converting this signal to voltage and sends it to the motors.
  6. The motors now are producing the needed thrust to move the drone the way you wanted.

Drone components

Let’s start analyzing each of the components and see exactly what is the role for each of them.

Frame

This is the basic building block of a drone. It acts as a skeleton in which all of the other components are placed in such a manner that they uniformly distribute the drone’s center of gravity. Usually it needs to be as strong as possible but also as light as possible. That’s why they are generally made of carbon fiber.
They come in different styles and sizes but all have the same basic job.
This component will also determine what propeller size you’ll need to use. You can determine that by the frame’s size (the size of a frame is just the distance between the diagonal length (in mm) from the middle of one motor to the middle of the motor directly diagonal to it).

Propellers

Propellers are clove like blades structured to create a difference in air pressure. When in motion, they cut through the air creating difference in pressure between the top of the motors and the bottom. The top side is characterized by low pressure as compared to the bottom causing the drone to lift into the air.
The standard way to name propellers is 5x4x4. This means you have a 5 inch propeller with a pitch of 4 inches and there are 4 blades.

Motors

Motors are some of the most important components. They are the driving force of the drone and they provide thrust. Thus being crucial for the drone control in terms of direction and for correct propeller’s rotation. Still, the number of motors should be the same as the number of propellers.
Choosing the right motor is pretty important for the efficiency of the drone. Let’s take a look at a motor name found in the wild: DYS Samguk Series Wei 2207 2600kv Motor. The first number we encounter is 2207. This is specifying the dimensions of the motor, the motor is 22mm in diameter and have a 7mm height.
For more information on motors you can have a look at these resources:
Brushless motors
Choosing the right motors

Electronic Speed Controller (ESC)

This is an electronic control board that varies the motor speed. To make this possible, the ESC is taking commands from the Flight Controller and translate them into power to the motors. Thus every motor needs it’s own ESC.
It also acts as a dynamic brake. The component helps the ground pilot to approximate the height at which the drone is running in.

Flight Controller

The Flight Controller is the “brain” of the drone and it’s where all the magic happens. It interprets input from receiver, GPS module, battery monitor, IMU and other onboard sensors. It regulates motor speeds, via ESCs, to provide steering, as well as triggering cameras or other payloads. It controls autopilot, waypoints, follow me, failsafe and many other autonomous functions. The flight controller is central to the whole functioning of your drone.
It also determines and calculates the drone’s altitude in respect to the amount of power it consumes.

Power Distribution Board (PDB)

The PDB job is simply to distribute the power from the battery to the other relevant components such as: ESCs, Flight Controllers, VTX, FPV cam, Receiver, LEDs, etc hence the name Power Distribution Board.
Most of today’s PDB boards include BECs. A BEC stands for Battery Elimination Circuit. It basically represents a voltage regulator. If a voltage regulator would not be in place, you could easily burn out the other components by providing more voltage than the specific component can handle.

The battery

Now we get to the component that provides the power to your drone – the battery. Most drones use Lithium polymer (LiPo) batteries because they offer the best combination of energy density, power density, and lifetime on the market.
They are made by more cells packed together. So by adding more cells you add more voltage.

R/C Receiver

Often a standard r/c radio receiver unit. The minimum number of channels needed to control a quad is 4, but 5 is usually recommended.

R/C Controller

The Controller is what the pilot holds in the hands and send signals to the drone by playing with the joysticks.

FPV camera

FPV cameras are designed to have the lowest possible latency (the time it takes for it to capture a frame and send it back to you). Most FPV cameras do NOT provide HD output however as this increases the latency of the feed which is disastrous for FPV flying.

Video Transmitter

The camera would be useless without a video transmitter. This component is simply broadcasting the video feed back to the goggles.

Other drone technologies

Radar Positioning & Return Home

Many of the latest drones have dual Global Navigational Satellite Systems (GNSS) such as GPS and GLONASS.
The radar technology in the drone will signal the following on the remote controller display;

  • signal that enough drone GNSS satellites have been detected and the drone is ready to fl
  • display the current position and location of the drone in relation to the pilot
  • record the home point for ‘Return To Home’ safety feature

Obstacle Detection And Collision Avoidance Technology

Many drones are now equipped with collision avoidance systems. These drone vision systems use obstacle detection sensors to scan the surroundings, while software algorithms and SLAM technology produce the images into 3D maps allowing the flight controller to sense and avoid the object.

Internal Compass & Failsafe Function

Allows the UAV and remote control system to know exactly its flight location. Calibration of the Compass is required to set a home point. The home point is the location where the drone will return to in case of loss of signal between the drone and the remote control system. This is also know as “fail-safe function”.

No Fly Zone

Actually a lot of the already made drones out there waited to be sold include a “No Fly Zone” feature to increase flight safety and prevent accidental flights in restricted areas.
That’s why you better build your own :smiley:

Conclusion

Drone technologies have evolved significantly in the past few years. Thus, a lot of new technologies are on the way and a lot of improvements are waiting to be made. I think it’s a necessary thing you need to understand nowadays because they will soon be everywhere. From the Security view, this is a cool thing and a terrifying one at the same time because they are not so secure, so you can easily take control of one. But, you can also create drones for operations with a specific task in mind. A great example is the 0x00sec drone !
It’s pretty expensive to build your own but you will learn a lot and have a great experience.

I’m sorry that I haven’t contributed to the community for a while and I have been inactive for so long, but now I’m back and hope we can continue to spread knowledge and wisdom.
Cya on the IRC and thanks for reading !