There has been a rising interest in the drone industry over recent years. However, multi-rotor devices have been around since 1922, with the first being named the de Bothezat helicopter which was attributed as a dedicated project to the, once existing, United States Army Air Service (USAAS). Nowadays, with the emergence of the internet, anyone is capable of learning the fundamentals behind the construction of an RC multi-rotor. Many open source drone projects (such as Ardupilot) have been presented to the public as a means of improving on the current technology and taking drones to new heights (excuse the pun). That being said, let’s look at the fundamental components for making a basic DIY drone.
Subsystems to Consider
Every drone is composed of these basic elements:
- Flight Controller: This is a dedicated integrated circuit (IC) that houses the brains of the operation. With multiple propellers, you need a system that is able to evaluate the current orientation of the drone and assess it against the stable position that the drone would like to assume. In simple terms, this is your Proportional, Integral and Derivative (PID) controller. A flight controller will, almost always, house any combinations of a magnetometer, accelerometer, barometer and GPS, each of which works to orient the UAV, produce a GPS lock and measure roll, pitch and yaw.
- Drive Train: The drive train consists of the three components that give your drone flight. They are, usually, directly connected to your flight controller and work to propel the drone based on remote instructions provided. The core components of your drive train are:
- Motor: For the sake of this article, we will only be discussing Brushless DC Motors (BLDC). These are motors that are largely governed by a revolving, induced, magnetic field. By providing a current to each of the 3 windings of the motors (each current has undergone a phase shift of 120° – 3 x 120° = 360° – A Full Circle!) through the Electronic Speed Controller (ESC).
- ESC: The ESC is a dedicated IC that converts a continuous DC power supply, along with a pulse width modulated (PWM) signal (typically provided by the flight controller), into the 3-phases of current.
- Propellers: Unlike the previous two, there is nothing too electronically technical here. Propellers can come in various forms and sizes. The main variables of concern that accompany quality propellers are: Propeller size (length of the blades), Pitch (Angle of attack for the blades) and material (typically polymer plastic vs carbon fiber).
- Batteries: In the case of batteries, your industry standard will be the Lithium-Polymer Battery (Li-Po), note that this is NOT the same as the Lithium-ion battery. Before purchasing your first Li-Po, it is important to read up on the standard handling procedures for storage, charging and discharging of batteries. Batteries produced energy due to a slow and continuous chemical reaction that exist between two relatively reactive elements. This reaction tends to store potential energy which can be harnessed for electronics. That being said, with any chemical, there comes a list of warning signs and safety data sheets (by WHMIS standards).
- Frame: The frame is typically an easy question to answer. Multi-rotor frames come in all shapes and sizes. You should always consider the purpose of your flight (racing, filming, parcel carry, logistics etc.). It is best to start off with a quad-copter (4 motor) frame and build your way up. The more complex the frame, the more work will be needed to coordinate the motor arrangement and to find storage for all of your wires.
- Power Distribution Board (PDB): The PDB is a dedicated IC that works to accept power from you battery and distribute it to the respective subsystems (the ESCs –> Motors and the flight controller). It is typically a simple circuit with a collection of plugs to accept cables for power transmission.
- Remote Control and transceiver: This combination works to give you wireless control of your DIY drone. The transceiver is a small circuit with multiple pins that allow you to plug directly into the flight controller. Following a basic remote set-up, the transceiver, will work to receive instructions from your remote controller and relay them over to the flight controller, which will, in-turn, translate those commands into coordinated instructions to the ESCs and motors. The transceiver will also transmit basic status information to the display on your remote for a basic SIT-REP of your drone.
The above information should help equip you with the basic terminology that is associated with a DIY drone project. You are now one step closer to building that sleek drone that will soar the skies and build your confidence in mechatronic design.
We will be working to release detailed articles on each component with specifics on a weekly basis.