What a drone is and how it works: components and technology
A drone is much more than a camera with propellers. To stay in the air, it needs to coordinate motors, sensors, positioning systems, wireless communications, and software capable of making constant corrections during flight.
When the pilot moves a lever on the control, the command is transmitted to the drone, the controller calculates how it should respond, and the engines modify their speed. At the same time, sensors check tilt, height, orientation and position to keep the aircraft stable.
In this guide you will learn what a drone is, what parts make it up and how its engines, propellers, sensors, GPS, flight controller and safety systems work together.
For a broader view of its uses, categories, regulations, and selection criteria, you can consult our complete guide to drones.
What a drone is and what UAVs and UAS mean
A drone or drone is an aircraft that can fly without having a pilot on board. It can be controlled remotely, perform assisted maneuvers, or follow certain programmed instructions using its flight system.
Although often used synonymously, the terms drone, UAV, and UAS do not mean exactly the same thing:
- Drone or drone: common term used to refer to an unmanned aircraft.
- UAV: acronym of Unmanned Aerial Vehicle. It refers primarily to the aircraft.
- UAS: acronym of Unmanned Aircraft System. It includes the aircraft, the command or control station, the communication links, and other elements necessary to operate.
Not all drones have four propellers either. There are multirotors, fixed-wing models, and hybrid configurations. These differences are developed in our guide on the different types of drones.
In this article we will focus mainly on the operation of multi-rotor drones, which are the most common among individual users.
Why a drone can fly
A multirotor flies thanks to the thrust generated by its propellers.
The motors rotate the propellers at high speed and move air downwards. In response, a counterforce is generated that propels the aircraft upwards.
Support, thrust and weight
To take off, the combined thrust of the propellers must exceed the weight of the drone.
When thrust and weight are balanced, the aircraft can be kept at approximately the same height. If the thrust increases, it rises; if it decreases, it falls.
In a quadcopter, two propellers usually rotate in one direction and the other two in the opposite direction. This configuration helps compensate for torque and allows control of the aircraft's orientation.
The four moves: throttle, pitch, roll and yaw
The movement of a drone is controlled by four fundamental commands:
- Throttle or power: regulates joint thrust and allows ascending or descending.
- Pitch or pitch: tilt the aircraft forward or backward.
- Roll or warping: tilt it to the left or right.
- Yaw or yaw: it makes it rotate on its vertical axis.
To move forward, for example, the controller reduces and slightly increases the power of certain motors. The drone tilts forward and some of the thrust begins to move it horizontally.
Stability depends on these variations being rapid, coordinated, and proportional to the pilot's commands.
Main parts of a drone
Although the configuration changes depending on the model, most multirotors share the following components:
| Component | Main function |
|---|---|
| Chassis or structure | It supports and protects the components |
| Engines | They transform electrical energy into motion |
| Propellers | They generate the thrust necessary to fly |
| ESC | They regulate the speed of each engine |
| Battery | It supplies power to motors and electronics |
| Flight controller | Processes orders and stabilizes the aircraft |
| IMU | Measures acceleration and rotation speed |
| Barometer | Helps estimate and maintain height |
| Magnetometer | Provides a guidance reference |
| GPS or GNSS | Helps calculate position |
| Receiver and antennas | They receive orders from the command |
| Transmission system | Send telemetry and image to the pilot |
| Camera | Capture photos or videos |
| Gimbal | Stabilizes and orients the camera |
| Firmware | Manages electronic operation |
Chassis
The chassis is the structure on which the motors, battery, and electronic components are mounted.
It must be rigid enough to maintain the drone's geometry and, at the same time, lightweight so as not to unnecessarily increase energy consumption.
Engines and propellers
Motors convert electrical energy into rotary motion. Propellers transform that movement into thrust.
The size, shape and inclination of the propellers influence efficiency, noise, speed and load capacity.
Electronic speed regulators
ESCs, or electronic speed regulators, control the power sent to each motor.
The controller continuously transmits instructions to the ESCs to accelerate or reduce the speed of the motors. Without this independent regulation, the drone would not be able to stabilize or change direction precisely.
Battery
Most drones use lithium batteries, mainly LiPo or Li-ion.
Real autonomy depends on factors such as:
- Battery capacity.
- Weight of the aircraft.
- Speed.
- Temperature.
- Wind.
- Maneuvers performed.
- Accessories installed.
- Battery condition and age.
The time advertised by manufacturers is usually obtained under favorable conditions, so the actual duration may be shorter.
Flight controller
The controller is the central system that coordinates the flight.
It receives commands from the pilot, consults the sensors, calculates the necessary response, and determines how much power each ESC should send to its engine.
It also manages functions such as:
- Stabilization.
- Flight modes.
- Positioning.
- Return to the point of origin.
- Height or distance limitations.
- Battery warnings.
- Response to signal loss.
How a drone works step by step
Operation can be understood as a continuous circuit between the pilot, controller, motors and sensors.
1. Initialization of systems
When you turn on the drone, the controller checks the status of the battery, sensors, motors, communications and positioning system.
During this phase, the point of origin can be established and checks of the IMU, compass, or visual system can be performed.
The pilot should not take off until the application confirms that the necessary systems are available.
2. Sending the order
The pilot moves a lever, presses a button, or selects an automatic function.
The controller converts that action into a digital signal and transmits it via the control link.
3. Controller processing
The controller receives the command and compares it with the current state of the aircraft.
To perform the calculation, use information such as:
- Tilt.
- Rotation speed.
- Estimated height.
- Orientation.
- Position.
- Travel speed.
- Battery status.
4. Engine regulation
After calculating the maneuver, the controller sends an instruction to each ESC.
Regulators modify the power of the motors. Differences in speed between them cause the drone to ascend, descend, tilt or rotate.
5. Correction using sensors
The sensors check if the actual movement matches the requested one.
When they detect a deviation, the controller adjusts the motors again. This process is repeated continuously during flight and forms a closed-loop control system.
Thanks to these corrections, an assisted drone can level itself, maintain height, or maintain a position despite minor disturbances.
6. Sending telemetry and video
While flying, the aircraft sends information to the controller or application.
This telemetry may include:
- Battery level.
- Height.
- Distance.
- Speed.
- Signal quality.
- Number of satellites.
- Sensor status.
- Security notices.
When a camera exists, video can also be transmitted in real time.
What sensors a drone uses
The sensors allow the controller to know the approximate status of the aircraft.
Not all models include the same systems and their behavior may change depending on the environment.
IMU: gyroscope and accelerometer
The IMU or inertial measurement unit usually integrates, among other elements, a gyroscope and an accelerometer.
The gyroscope measures the rotation speed on the different axes. The accelerometer detects accelerations and helps estimate orientation and movements.
The controller combines this data to determine if the drone is tilting or rotating and apply the necessary corrections.
Barometer
The barometer measures changes in atmospheric pressure and helps estimate variations in height.
It is especially useful for maintaining a relatively stable altitude, although pressure can change due to weather conditions and other factors.
Magnetometer or compass
The magnetometer provides an orientation reference with respect to the Earth's magnetic field.
May be affected by:
- Metal structures.
- Vehicles.
- Power lines.
- Speakers.
- Magnets.
- Electromagnetic interference.
That is why it is not advisable to take off from metal surfaces or ignore the application's compass warnings.
GPS and other GNSS systems
The GNSS receiver uses signals from satellite constellations to estimate the aircraft's position.
Depending on the model, you can combine:
- GPS.
- Galileo.
- GLONASS.
- BeiDou.
This information allows you to maintain your position, record routes, and use automatic functions.
Visual sensors and obstacle detection
Some drones incorporate cameras, infrared sensors, ultrasound, time-of-flight systems, or other technologies to observe the environment.
They can be used for:
- Maintain the position close to the ground.
- Estimate the distance from a surface.
- Detect obstacles.
- Brake.
- Surrounding certain objects.
- Assist during landing.
Its operation may worsen in low light, uniform surfaces, transparent objects, thin branches, cables, water, or rapid movements.
Therefore, obstacle detection should not be interpreted as a guarantee against collisions.
How a drone's GPS or GNSS works
Although it is commonly referred to as “GPS”, many drones actually use a GNSS receiver compatible with multiple constellations.
The receiver calculates a position estimate from the received signals. The controller combines that result with the IMU, barometer, compass, and, when available, visual sensors.
This combination is known as sensor fusion.
Thanks to positioning, the drone can:
- Maintain a position.
- Measure the distance from the point of origin.
- Record the route.
- Execute scheduled missions.
- Activate certain return functions.
- Show your position on the map.
However, accuracy can be reduced near tall buildings, metal structures, mountains, areas with interference, or places with poor sky visibility.
A drone can also fly without GPS, but it may not maintain its horizontal position in the same way. Its behavior will depend on the flight mode and other available sensors.
How the controller communicates with the drone
Communication is not just about sending orders. Many computers have several simultaneous information flows.
Control link
Transport orders from command to aircraft:
- Power.
- Address.
- Orientation.
- Camera movements.
- Activation of functions.
Its stability depends on the system used, antennas, distance, obstacles and interference.
Telemetry
Telemetry sends information from the drone to the pilot.
It allows you to monitor the condition of the aircraft and receive warnings during flight.
Video streaming
Drones with cameras can send a live image to the controller, phone, or glasses.
The quality and latency of that transmission depend on the system used. In immersive flight, low latency takes on special importance; this operation is developed in our guide on how FPV drones work.
Security and fault response systems
Safety systems reduce risks, but they do not eliminate pilot liability or guarantee that the drone can recover from any problem.
Return to the point of origin
The Return to Home or RTH function attempts to direct the aircraft to a previously saved point.
It can be activated manually or, depending on the model and configuration, in situations such as:
- Prolonged signal loss.
- Battery level determined.
- Pilot's order.
To function correctly, it needs to have a valid position and sufficient energy.
An appropriate height must also be set. A drone without front sensors could initiate the return journey and encounter an obstacle during the journey.
Signal loss
The behavior can be configured in some models to:
- Return.
- Stay suspended.
- Land.
The answer depends on the aircraft, flight mode, available positioning and selected configuration.
Low battery
The system can issue warnings, limit certain functions, recommend return, or initiate a landing.
Waiting for the battery to be practically dead increases the risk because wind or distance can prevent a safe return.
Obstacle detection
Sensors can help brake or modify the trajectory, but they have limits on distance, angle, speed, and lighting.
Some flight modes may reduce or disable certain detection functions.
GPS loss or interference
When positioning degrades, the drone may depend on the IMU, barometer, or visual system.
This can cause it to stop maintaining its horizontal position and start moving in the wind.
GPS, compass or interference warnings should not be ignored.
Security technology also does not replace compliance with the regulations for drones in Spain.
Automatic functions, autonomous flight and artificial intelligence
Not all automated functions use artificial intelligence.
A drone can follow a programmed route, maintain a height, or return to the point of origin using conventional rules, sensors, and algorithms.
Among the automatic functions we find:
- Assisted takeoff and landing.
- Position maintenance.
- Routes through crossing points.
- Return to the point of origin.
- Orbits around a point.
- Tracking a trajectory.
Artificial intelligence and computer vision can be used for more complex tasks, such as:
- Recognize people or objects.
- Follow a subject.
- Interpret images.
- Select a trajectory.
- Analyze data collected during a mission.
However, the degree of automation varies greatly between models. It should not be assumed that a drone can make safe decisions on its own in any environment.
Conclusion
A drone stays in the air thanks to the coordination between its motors, propellers, ESC, controller and sensors.
The controller receives commands from the pilot, calculates how each engine should respond, and uses information from the IMU, barometer, compass, GNSS, and visual sensors to correct movement.
Understanding this chain of operation helps interpret application alerts, correctly use automatic functions, and react better to changes in signal, battery, or positioning.
The next step is to learn how to fly a drone for the first time and apply this knowledge in a safe environment.
Frequently asked questions about how drones work
Drone is the common term. UAV refers primarily to the unmanned aircraft and UAS includes the complete set: aircraft, control, communications and other elements necessary to operate.
The controller uses data from the IMU and other sensors to detect deviations and continuously modify the speed of the motors.
Yes, but its behavior will depend on the flight mode and the available sensors. Without positioning, it may not automatically maintain a horizontal position.
You can estimate it by combining data from the barometer, GNSS, visual sensors, infrared systems, or other technologies, depending on the model.
No.
The opposite rotation helps compensate for the torque generated by the engines and allows control of the aircraft's rotation about its vertical axis.
It depends on the model and configuration. It can return, stay suspended, or land. These options should be checked before the flight.
No. Some do not have anti-collision sensors and others only detect obstacles in certain directions or conditions.
No. It depends on the stored position, battery, signal, sensors, configuration, and obstacles present on the route.
No. The controller coordinates the aircraft. The GPS or GNSS receiver is one of the systems that provides you with position information.
No. Many automatic functions use conventional algorithms. Artificial intelligence is usually reserved for recognition, tracking, image analysis, or advanced planning.