Northwestern Polytechnical University scientists in China have developed a drone that can stay in flight indefinitely using a remote charging system with a target-tracking laser on the ground. The drone’s photoelectric converter captures energy from the laser, though efficiency of wireless power transmission is not high, ranging from 50-85% at the transmission end and losing around 50% again at receiving end.

Electricity being cheap, losses in charging drone via wireless transmission are acceptable as it allows for continuous surveillance. PowerLight, a Washington-based company, previously known as LaserMotive, had also successfully demonstrated a similar charging system in 2012, keeping a large drone airborne for 48 hours in wind tunnel and powering one of Lockheed Martin’s Stalker drones from ranges up to 600m outdoors.

NPU team developed an “intelligent visual tracking algorithm” to target the beam on the drone, and an adaptive beam shaping system to adjust for changes in atmospheric density. They also designed a method to identify obstacles and rapidly adjust the beam power to a safe level. They tested it with a small quadcopter, and demonstrated it working indoors with lights on and off, and outdoors at night, reaching altitudes of around 10m.

A ground-based gimbal tracks and targets the drone during flight. NPU team tested it indoors and outdoors in various lighting conditions including daylight, artificial light and low light.

A ground-based gimbal tracks and targets the drone during flight. NPU team tested it indoors and outdoors in various lighting conditions including daylight, artificial light and low light.

Laser systems’ long-range capabilities suggest the technology could pave the way for higher-altitude drone operations and create persistent airborne platforms similar to low-altitude satellites. However, the use of multicopter-style platforms will likely be limited by weather conditions.

The military potential of the technology may also face regulatory pushback as the devices would point lasers into the sky. PowerLight, a company closer to commercialization, is working on long-range, lightweight and compact wireless laser power transmission with functional safety shutdown systems and ability to operate in any weather.

The capability to charge electric aircraft in flight could greatly benefit the emerging eVTOL industry.

The capability to charge electric aircraft in flight could greatly benefit the emerging eVTOL industry.

Wireless power could revolutionize electric aircraft, particularly eVTOL air taxis, whose major concerns are battery density and range. A city-wide grid of laser chargers supplying energy as the aircraft fly overhead could make them more viable for commercial use, but significant work remains before it is legally approved and ready for urban use.

Sources: China Daily, South China Morning Post