Systems

Within each drone are several different systems to aid in navigation. Arguably, one of the most important systems is the Global Positioning System (GPS). The GPS uses satellites to determine its position. Without GPS, most drones will not be able to hold position without manual corrections made by the hand controls of the operator. Magnetic interference is something that largely affects the GPS unit’s ability to operate as intended. The ground station controller communicates with the aerial system through the use of radio transmissions across the 2.4 GHz frequency channel. Microwave antennas and high voltage lines create strong radio and magnetic interferences that affect the radio transmission which controls the drone.

Another vital system for flight is the Inertial Measurement Unit (IMU). This system uses an accelerometer and gyroscope to determine the movement of the drone. The IMU working with other onboard systems can determine the drone’s Degree of Freedom (DOF), which can be measured in tilt, roll, and pitch. Before each flight, it is important to calibrate the drone’s magnetometer, also known as the onboard compass. The purpose of the compass calibration is to correct the drone’s onboard flight system so that it is set for magnetic north, not true north.

If the drone loses signal, it will follow the operation preset selected during takeoff. When the drone loses signal, it will either initiate a return to home sequence, flying itself back to its launch location and landing, or it will attempt to maintain the position in a fixed hover until communication is restored. Some newer drones have dual modular redundancy to help prevent system failure that would lead to a crash. If one system unexpectedly goes offline, a secondary system running in parallel would keep the drone in operation.

Depending on the operational environment, key technical specifications for unmanned vehicles include endurance, size, payload, range, communication and navigation capabilities, and deployment mechanisms (Bellingham and Rajan 2007; Curtin et al. 2005).