**2. Quadrotor UAV concept**

The quadrotor consists of a main body having four centrally connected arms and four brushless motors attached to each end of the arm. Four rotors are attached to each engine whose rotation of the propellers/rotors is controlled by radio control. All of these motors are connected to controllers to control the speed of each individual motor. These controllers are connected together in parallel with the power

**Figure 1.** *UAV assembly diagram [13].*

*Quadrotor-Type UAVs Assembly and Its Application to Audit Telecommunications Relays DOI: http://dx.doi.org/10.5772/intechopen.104254*

distribution board. Further, a battery is used as the power source. The assembly diagram of the quadcopter drone is shown in **Figure 1** [14].

The motor distribution is powered by a battery. In this way, the board evenly distributes power to the four electronically controlled drives, eventually reaching each motor. The accelerometer measures the angle of the quadrotor on the X, Y and Z axes and adjusts and stabilizes the revolutions per minute (RPM) of each motor [14, 15].

The following paragraph describes the components we have selected to make this drone.

### **3. Frame design and building**

The first approach to designing the frame is to mount each arm at a central intersection to provide convenient mounting points and good support for each frame component [16]. The two arms are mounted vertically in the center and fixed by two boards. These boards are the basic support for flight controllers, batteries and distribution boards. Motors are attached to the ends of each arm [14]. The components used to assemble a quadrotor drone are described below.

#### **3.1 Quadrotor SK450 frame**

The frame is made of durable fiberglass and the arms are made of light nylon polyamide, with a height of 450 mm and 80 mm.

#### **3.2 Carbon fiber propellers 12 in**

Propellers are used to generate aerodynamic thrust. The first pair of propellers rotates clockwise (pusher) and the other pair rotates counterclockwise (puller) [17]. The thrust generated by propellers depends on the density of the air and the speed of the propeller, its diameter, the shape and surface of the blade and its pitch.

#### **3.3 Turnigy multistar 980 Kv motor**

The engine has a significant impact not only on flight time, but also on the payload the vehicle can carry. It is imperative to use the same engine throughout the same vehicle, as if pair of engine were of the same brand and model. Also, from the same production, their speeds may be slightly different and it is the air traffic controller who takes care of this [17].

#### **3.4 Electronic speed controller (QBrain ESC)**

The electronic speed controller (ESC) controls the speed and direction of the motor by inputting signals from the flight controller. The ESC must handle the maximum current drawn by the motor.

#### **3.5 Pixhawk flight controller**

The flight controller is a Pixhawk Mini programmable autopilot microcontroller manufactured by 3dr with enhanced sensors (accelerometer, gyroscope, etc.) that provide excellent flight stability and navigation to specific GPS coordinates.

### **3.6 Radio remote control turnigy 9X**

The radio control receiver sends a wireless input to the vehicle and uses at least four channels connected to the following to control the movement of all vehicles.

1.Pitch (controls the vehicle to forward/backward motion).


#### **3.7 2200 mAh lithium battery**

The batteries are lightweight and offer high capacity with high discharge rates. Battery capacity is measured in ampere-hours (Ah), and the larger the capacity, the longer the flight time [18].
