Knowing UAV Systems, Sub-Systems, and Components

Earlier, we read about the forces that work on a drone, its major hardware, systems, and sub-systems, and the systems that are applicable to the drone. Now, we will go ahead by learning about the development of these hardware systems. In this chapter, we will learn about the major concepts, terminologies, and laws that are helpful in the development of drones as a whole. This would let the user design their own system as per the specifications given.

In this chapter, we will learn how to select the best components for the drone as per their specification requirements and how they can be integrated to develop a drone. We will go through the following topics to help you understand the concept in detail:

• Understanding and conceptualizing the system
• Designing the propulsion system
• Designing and developing the airframe
• Developing the control system
• Selecting the navigation and communication system

Technical requirements

In this chapter, the major technical requirements are basic high school physics, knowledge of the resultant forces that act on the body, and basic electrical engineering and calculations. It would be beneficial to have an understanding of circuit voltage, current, power, batteries, and so on. Experience of handling electrical instruments is a plus.

Understanding and conceptualizing the system

Understanding and conceptualizing helps us to build every kind of drone for its dedicated application and purpose. As we saw in Chapter 1 the major applications for which a drone can be used, we now see how drones can be conceptualized and developed.

A drone is basically a platform that can fly into the air with a certain amount of payload capacity, which we have already studied with maximum take-off weight (MTOW). Thus, a drone platform can be helpful in transforming a drone for different applications by applying the permissible payload to it and optimizing its weight, endurance, size, and power.

When we are conceptualizing a system, we need to think about and decide on the following things:

• The application: The purpose of this is to know the application and purpose for which the drone is built, for example, an urban mapping by a LiDAR payload, a land survey using an RGB camera, crop spraying/seeding in agriculture, day and...

Designing the propulsion system

The propulsion system or power train is the most important system in the drone. It’s the backbone of the drone due to which the drone takes off in the air safely, performs missions, gives the required endurance, and is able to make sharp maneuvers and withstand high winds during the course of action. As we studied in an earlier chapter that the weight of the drone is key to choosing its propulsion system, we can look ahead for the approximate weight distribution of different components for the approximate total weight of the drone.

The propulsion system of the drone consists mainly of motors, propellers, ESCs, power distribution boards, and a battery. These are the key components whose weights play a key role in deciding on the MTOW of the drone. Let’s have a look at these components and a methodology to decide on the best components based on the working experience of developing a multicopter.

Let’s consider a drone whose total...

Designing and developing the airframe

An airframe is the skeleton of the drone that holds the avionics and other components together tightly and stiffly. It’s the structure that actually moves into the air and gets the effect of the environment; hence, an airframe should be rigid, strong, and lightweight. We can either design our own airframe using the different software available and following the composite manufacturing process or we can use the airframes available on the market.

Whether we are designing the airframe or getting the airframe, we need to consider the following points that would be helpful in giving us an idea of how much load the drone can carry and how maneuverable it can be:

• Professionally engineered: When an airframe is developed in a laboratory, certain materials are selected, such as carbon fiber, glass fiber, and so on, and have to go through the manufacturing process of cutting drilling. The material, that is, carbon fiber, is laid up in molds...

Developing the control system

In this section, we will cover control system development.

Electronic speed controllers and flight controllers

An electronics speed controller (ESC) is a small device that comes between the flight controller (FC) and the BLDC motors. An ESC, as the name suggests, controls the speed at which the BLDC motor rotates as per the signals received from the flight controller. Each motor requires one ESC to control its speed and is connected to the flight controller. The FC simultaneously has pulse with modulation (PWM) pins to which the ESC is connected. The FC gives the PWM/DShot signal to the ESC as per the commands given by the GCS RC to run the motors. The ESC gets power from the battery and signals from the flight controller. The following diagram illustrates this setup:

Figure 4.4 – The workings of an ESC

The ESC is connected to the battery and supplies the battery voltage to the motors. The ESC is a kind of oscillator...

Selecting the navigation and communication systems

Navigation and communication systems are the most important systems in the drone. The communication system helps to command and control the drone over longer distances, and the navigation system helps the drone decide its north and guides the system to the waypoints in an autonomous mission.

Communication systems

A communication system basically consists of a radio modem and an antenna that is connected to the ground control station and the drone, which are connected to each other. This system helps to program the drone for autonomous missions and command the drone mid-flight to perform specific tasks. Let’s see the parameters at which a communication system exists (examples of a radio modem is RFD900 433Mhz.):

• Range of drone: Range is a crucial factor that helps the engineer to decide and integrate the communication system. As the range requirement increases, the radio modem and antenna requirements also increase...

Summary

In this chapter, we have learned about the theory and selection of the key parts of the drone and the criteria that can be selected for them from the propulsion system to the GNSS device. This is the key concept of making a blueprint for the drone on all the parts available.

In the next chapter, we will focus more on the assembly and integration of these parts and the configuration software used for flying.