Development of Battery-Independent Illumination Drones Integrated into Tethered UAVs for Extended Operations

Abstract

This study presents the design of an unmanned aerial vehicle (UAV) specifically developed for extended illumination in surveillance, search and rescue (SAR) operations, security enforcement, border surveillance, and other applications requiring lighting, particularly in disaster areas. Traditional battery-powered UAVs have limited operational time; therefore, a tethered drone design was implemented in this study to overcome flight duration constraints. The direct current (DC) energy required for the tethered drone is supplied by a Gold Series switch-mode power supply (SMPS) mounted on the drone. The alternating current (AC) energy needed for the SMPS is transmitted through a cable. Additionally, the light-emitting diode (LED) projector, operating on AC 220 volts, is powered by the same cable that supplies the drone, eliminating the need for an additional DC converter. This design choice reduces weight and ensures an optimized configuration. The projector is mounted on servos with dual-axis capability, allowing both horizontal and vertical movement to precisely illuminate the target area. Although studies on tethered and illumination drones exist in the literature, this work combines two distinct drone systems to create a more efficient UAV design. In the design process, considerations were made for various environmental conditions, particularly wind. Consequently, the thrust-to-weight (T/W) ratio was determined to be 1.54. For cable cross section, a 1.5% voltage drop was accounted for, yielding a required cross section of 1.16mm². However, to ensure safety and reliability, a cable with a cross section of 1.5mm² was selected. This proposed model, distinct from other studies in the literature, offers a practical design for field applications, particularly for night SAR operations in disaster zones such as earthquake sites, due to its point-focus illumination capability and extended flight duration.