An unmanned aerial vehicle, commonly known as a drone, is a small aircraft that does not have a human pilot onboard. Drones can be controlled remotely with a handheld device called a controller, or they may fly autonomously using software-controlled flight plans embedded in their embedded systems. Drones have sensors and global positioning system (GPS) modules that communicate with the controller via radio waves. They are typically made of a lightweight composite material that reduces weight and maximizes maneuverability.
Some drones are equipped with GPS modules and a suite of onboard sensors, such as ultrasonic, laser or lidar distance sensors that illuminate the ground to calculate its distance, chemical sensors, and stabilization and orientation sensors. Others are fitted with visual cameras that offer still and video images, including color, red, green and blue or multispectral sensors. These capture both visible and nonvisible wavelengths, such as infrared, to detect gases, minerals or vegetation. Accelerometers, gyroscopes, magnetometers and barometers are also common drone features.
Drones can be used for many purposes, such as assessing crop health, measuring water quality or monitoring wildlife and natural disasters. They are also popular among sports fans, who use them to record game footage that would be difficult or dangerous to get otherwise. The drones also serve a vital role in military operations, such as delivering supplies to forward operating bases, conducting search-and-rescue missions and providing reconnaissance and surveillance support.
Despite their popularity, drones have sparked privacy and security concerns. Voyeurs and paparazzi have used drones to photograph private homes, events or other locations that are assumed to be private, and they can also pose a threat to safety by flying too close to commercial aircraft. Governmental agencies and businesses have responded by imposing drone regulations and requiring all drones to be registered, with some countries also establishing no-fly zones around airports.
There are a wide variety of drones available, from compact models such as the Parrot Anafi and PowerVision PowerEgg X to larger ones such as the Boeing Integrator. Most of these drones are rotor-based and have four propellers, although there are models with three, six and even eight propellers. The drones are powered by electric motors that convert mechanical energy into rotary motion. They also have a central flight control that works to maintain stability and a navigational sensor that measures the strength and direction of the magnetic field, functioning like a compass, to indicate its position.