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The photovoltaic microplane has dimensions of 0.15 m x 0.15 m and a weight of only 0.071 kg. According to its creators, it is the smallest rechargeable solar multirotor developed to date. It uses Sunpower solar module technology, with an efficiency of 22.6%, and a 0.3 Ah storage system based on lithium polymer batteries.
Researchers at Queen Mary University of London have built a prototype multirotor micro aerial vehicle that runs on photovoltaic energy and can fly for an average of 3.5 minutes.
Scientists claim their microdrone is the smallest solar-rechargeable multirotor developed to date, measuring 0.15m x 0.15m and weighing just 0.071kg.
For the photovoltaic system, the research team chose solar cells with a power per unit area of ??219 W/m2, manufactured by the American company Sunpower. It used a micromodule with a thickness of 0.000165 m, a mass of 0.0063 kg, a surface area of ??0.0156 m2, and a power conversion efficiency of 22.6%.
For the drone technology, they used a commercially available M:Tech quadcopter with a power consumption of 3.57 W. “The minimum power requirements of the M:Tech drone in hover are 2.59 times the output provided by this theoretical solar cell that meets the surface size requirements of the micro aerial vehicle (MAV),” the academics explain. “The limiting factors here are solar irradiance and solar energy conversion efficiency.”
They also stressed that the useful surface area of ??the quadcopter is too small to ensure solar-powered flight without energy storage. “The minimum solar panel surface area needed for a purely solar-powered flight would be 0.128 m × 0.128 m,” they specified. “For the Micro Solarcopter to float exclusively on solar power, it will need about 12 W, so it will require a surface area of ??0.234 m × 0.234 m, which is outside the size restriction of the MAV.”
The aerial vehicle also integrates a 0.3 Ah storage system based on lithium polymer batteries, a 32-bit flight controller, a Nine Eagles P-51 micro electric motor, a gearbox coupled to a Turnigy Micro-propeller. quad, a first-person view (FPV) camera, two switching voltage regulators, a buck-boost converter, and a MOSFET to turn the power on and off to the FPV camera. “The MOSFET was strategically placed so that it was exposed to the rotor airflow during flight and provided some level of cooling,” the team explains.
The selected battery has the best power density compared to other candidates, along with notable energy density, specific power and specific energy. “The battery is advertised with a discharge capacity of 45-90 C,” the group states. “The Micro Solarcopter stays at about 15 C charge with this battery.”
The battery may also enter hibernation mode when fully discharged for more than 40 days. In this way, the aerial vehicle does not use battery electricity during periods of little or no light.
Through a series of tests, the researchers verified that the solar aerial vehicle can fly at more than 15 m high for about 3.5 min, “depending on the defined voltage cut-off setting, which directly influences the useful life of the battery. ”. The battery can be recharged in about 68 min under standard lighting conditions at 25ºC.
“This flight time is short compared to fixed-wing MAVs, but close to the endurance figures of multirotor MAVs, which are around 5 minutes,” they further explain. “The advantage, however, is that the Micro Solarcopter can land, hibernate and recharge its battery independently without having to return to a home base.”
Their findings were presented in the study “ Development of a solar powered multirotor micro aerial vehicle,” published in scientific reports . Looking ahead, they say they intend to solve drone recharging problems by creating mobile unmanned ground vehicles that would serve as larger photovoltaic units that would allow for faster recharging. |
