Autonomous combat drones
The method of propulsion therefore depends on the intended role of the UAV, but, as hypersonic or noiseless drones continue to be researched, it will not be long before entirely new propulsion systems are developed.
Sensors and communications To ensure a complete understanding of its surroundings, a UAV requires a vast selection of sensors, not limited to lidar, radar and GPS. Lidar, Light Detection and Ranging, works to create a 3D model of the surroundings. It does this by sending out a stream of rapid laser pulses and capturing the responses. This has the benefit of being very high precision, can work in the dark and can penetrate through vegetation to the underlying terrain, unlike conventional photographs (DJI Enterprise, 2022). This is useful for both real-time flight calculations and as useful surveillance information for future missions. However, the processing of lidar data can be complex, so specialized processing equipment must be included in the construction of the drone. Any excessive weight will decrease flight performance, but inadequate processing of data could lose vital information, or the drone itself. Once again, a compromise must be struck between lidar performance and flight performance. However, engineers will be looking for ever-more efficient ways of capturing and storing this data. Communication of data is vital on the battlefield. Surveillance drones will be integrated into a widespread communication network, using a wide range of different technologies for fail-safe transmission. For example, short-range drones may use direct line-of-sight transmission, using UHF radio frequencies. However, as the name suggests, this technology cannot be used beyond visual range of the drone, making the scope of use quite small, but it can be effective in wide open spaces. The major alternative is BVLOS (Beyond Visual Line of Sight), which pre-programs and autonomizes the drones' movements. This program can then be constantly adjusted by calculations from the inputs mentioned above (e.g. lidar), to ensure the drone can reach its destination despite a changing environment. However, drones can also communicate by bouncing HF-radio frequencies off the ionosphere and to remote control centres. This allows for constant communication, which can make them remote- controlled or remotely monitored. However, this makes communication very subject to atmospheric conditions, as the frequency needs to be adjusted or direction changed to ensure the signal is being reflected to the right place (Jollet, n.d.).
Control Systems Drones with jet engines will make use of typical fixed-wing technology of control surfaces and ailerons to keep them in flight. However, the story is entirely different for drones which use electric propulsion.
All BLDC drones, to varying degrees, are controlled by the same system – a PID controller, which stands for ‘Proportional, Integral, Derivative,’ which Sayed, E. (2024) explains as follows. This system continuously changes the power being used by each motor to correct, move and adjust the drone's position. An error value is calculated between the current position and the desired position. Power is then redistributed to minimize that error, essentially moving the drone closer to its intended position.
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