BY ZACC DUKOWITZ
15 February 2023
When it comes to using drones for commercial applications, battery life is one of the biggest limiting factors.
Extending battery life has proved a tough challenge, and one that the drone industry has been laboring away at for years.
All this work has produced steady progress, with battery life steadily increasing. But the gains in flight time for drones that fly using your standard LiPo batteries have been relatively small despite all the work put into extending them.
Some less common approaches to powering drones have been tested, and seem promising. One is using hydrogen fuel cells, and tests have also been made with powering drones using gasoline (though these don’t seem to have gone anywhere).
Of course, you can also use a tether to send power up to the drone, allowing it to stay aloft as long as you want—but this means the drone has to remain stationary, since it’s leashed to the ground by the tether.
But there may be a way to power drones from a removed power source without having to tether them to ground.
That’s right—we’re talking about powering drones with lasers.
Credit: Northwestern Polytechnical University
NEW BREAKTHROUGHS FOR LASER-POWERED DRONES
The idea of using lasers as a power source for drones has been around for at least a decade.
But new research conducted by scientists at the Northwestern Polytechnical University (NPU) in China has been making the news lately, showing progress in work toward making this technology viable.
The team of researchers at NPU have equipped a drone with a module that converts light energy into electricity, allowing it to capture power from a high-energy laser beam so it can stay in flight indefinitely.
The researchers have dubbed these UAVs optics-driven drones (ODDs).
Credit: Northwestern Polytechnical University
Of course, for this laser-powering method to work the laser needs to be able to automatically track the drone.
For this reason, the researchers have made the laser adaptive and given it the ability to track its target—the photoelectric conversion module on the bottom of the drone—using an “intelligent visual tracking algorithm.”
According to NPU researchers, the algorithm has proven effective in a variety of environments, as well as differing light and weather conditions.
The lasers used to power the drone also have an adaptive technology that allows them to shape their beams autonomously, adjusting intensity as needed based on the distance the drone is from the power source and in instances where an object is detected between the laser beam and the drone.
The laser-power drone technology was recently tested on a small quadcopter. Tests were conducted outside at night and inside with both the lights on and off.
In the tests, the drone reaches a height of just about 33 feet in the air (see below for images from the tests).
Credit: Northwestern Polytechnical University
So far the NPU system has proven to be pretty inefficient, losing about 50% of the energy transmitted from the laser.
But it works.
And that may be all that matters right now, given that electricity is fairly inexpensive and that the approach allows the drone to can stay in the air indefinitely.
OTHER LASER-CHARGING DRONE PROJECTS
Here’s a quick rundown of other noteworthy efforts to charge drones with lasers.
In 2012, U.S.-based PowerLight (formerly known as LaserMotive), demonstrated its wireless drone charging system by keeping a large drone in the air for 48 hours in a wind tunnel.
The system was also used to power a Lockheed Martin Stalker drone outdoors at a range of 1,970 feet in the air.
Today PowerLight says it’s working on long-range, lightweight wireless laser power transmission system. Watch the video below to learn more.
DARPA’s Drone Laser Project
In 2018, DARPA (Defense Advanced Research Projects Agency) announced a program called the Stand-off Ubiquitous Power/Energy Replenishment—Power Beaming Demo (SUPER PBD).
The goal of the program was to test technology that would charge aircraft while in flight using laser beams.
In DARPA’s approach, the aircraft has solar panels in its wings and batteries in its fuselage. At first the batteries provide power to the aircraft, but as they run down a laser beam is pointed at the craft’s solar panels, allowing it recharge and stay in flight.
DARPA selected a UAS called Silent Falcon made by a company of the same name for its laser tests.
Credit: Silent Falcon
In 2018, a startup called LakeDiamond made news for its idea to use lab-grown diamonds to recharge drones while in flight.
The diamonds allow laser beams to maintain strength over a long distance, letting them recharge photovoltaic cells on the surface of the drone. In LakeDiamond’s laser, the light produced by a diode is directed at a booster composed of reflective material, an optical component, and a small metal plate to absorb the heat.
THE BENEFITS OF CHARGING DRONES WITH LASERS
So why would you want to charge drones with lasers?
The obvious benefit is that you would no longer have to worry about battery life. Using lasers, you could hypothetically have a drone that could fly for as long as you wanted.
But there are specific use cases that would benefit from having a drone that can fly for a very long time—maybe even forever.
Here they are:
Disaster relief. During time-consuming emergency missions, like searching for victims after a flash flood or earthquake, the ability to have a drone remain in the air for long periods of time could be extremely helpful.
Traffic control. Traffic never stops, and continuously flying drones could be used to monitor traffic and help improve safety on the roads.
Security patrols. Security concerns are in place every hour of the day, a fact that supports the idea of having a constant “eye in the sky” to monitor the security of a building or perimeter.
Flying satellites. Laser-powered drones could be used for higher altitude drone operations, in which drones basically act like small low-altitude satellites.
The last one sounds a little unlikely, but it does reveal the places our imagination can take us when a drone is no longer limited by how long it can stay in the air.
Who knows—maybe we’ll see laser-powered drones rolled out within our lifetime. Results from the research being conducted today certainly makes it seem like a strong possibility.
AeroEnvironment's newest UAV is rumored to look at lot like the Helios Prototype, which crashed in 2003.
BY SAM BLUMPUBLISHED: MAR 7, 2019
AeroEnvironment’s newest drone will mirror its prior creation, the Helios Prototype.
A race is on to build a fleet of solar-powered drones that beam internet down to the Earth beneath them, and the tech titans are dominating this chase—or so we thought. But now that Google and Facebook both have dashed their plans for roaming unmanned internet planes, a lesser known company is partnering with NASA to bring the project closer to reality, according to an IEEE Spectrum report.
It is the Hawk 30, a massive 10-engine drone in the vein of previous UAVs made by Airbus and the solar-powered Odysseus plane that can fly for months on end. The product of Japanese tech giant SoftBank and U.S. drone manufacturer AeroEnvironment, the Hawk could soon embark on test flights, with a launch from NASA’s Armstrong Flight Research Center potentially slated for this week.
The Hawk, though part of a new $65 million partnership between the two companies, is part of the same family as previous UAVs AeroEnvironment built for NASA. One of those was the Helios prototype, which crashed in 2003 during a high-altitude test. The Hawk mirrors its ill-fated predecessor in both ambition and design. In 2001, the Helios reached the highest altitude of any winged horizontal aircraft when it ascended to 93,000 feet. The milestone set a new precedent for high-altitude, solar aircraft.
While it may be years from commercial readiness, the Hawk 30 has big implications for the broadening of wireless connectivity in remote regions, if indeed it can succeed where others have failed: Facebook made a splashy foray into the internet-beaming drone race by announcing Aquila, a solar-powered UAV the size of a Boeing 737's wingspan that used propellers to ply air. (The project was abandoned in 2017 after the drones were damaged in landings). Google too began vetting its sky-born internet capabilities in 2015, but later scrapped drones in favor of Project Loon, which uses high-altitude balloons to beam down internet.
The Hawk will still have to fend off competition from the likes of Airbus, but its prospects are lifted by AeroEnvironments connections with NASA. IEEE Spectrum reports the company is contracted with the space agency for three flight tests that will take the drone up to 10,000 feet, with the intention go much higher if initial tests are successful:
AeroVironment is paying NASA nearly $800,000 to supervise and provide ground support for the upcoming low altitude tests, which are scheduled to continue until the end of June. If those are successful, the company will go higher in its next round.
There's currently no word on the Hawk's communications payload capacity, but its creators certainly hope that it helps expand wireless internet access across the globe. First, though, it will have to make it out of testing unscathed.
Source: IEEE Spectrum
The use of a UAS to acquire geodata for mapping purposes has evolved beyond infancy and is now rapidly maturing. How will it evolve in the foreseeable future?
The use of an unmanned aerial system (UAS) – cameras and Lidar sensors mounted on an unmanned aerial vehicle (UAV or ‘drone’) – to acquire geodata for mapping purposes has evolved beyond infancy and is now rapidly maturing. How will UAS mapping evolve in the foreseeable future? To envisage where exactly UAS technology is heading, it is appropriate to start with the big picture before examining the details.
So what is the current big picture for unmanned aerial systems? How are they embedded in today’s society? First of all, our planet is confronted with climate change. The most threatening effects are sea-level rise and lengthy heavy rainfall putting valleys, rivers, lowlands and deltas at increased risk of flooding. Each year, the world’s population expands by more than the equivalent of the total number of inhabitants in Australia and Canada combined. Less than 250 years ago, just one billion people were living on this planet. Today, that number has reached nearly eight billion. This represents an annual population growth rate of over 1% and a doubling of the population every 70 years – which is less than a lifetime for many people. Remember this when you complain about overcrowded cities! The Industrial Revolution brought the world machinery to plough, sow and harvest fields – which freed peasants from hard labour on farms, but also transformed smallholdings into industrial operations and signalled the end of the idyllic pastoral scenes immortalized in 19th-century paintings. Since then, those peasants’ descendants have continued to move around in search of work, contributing to the rapid growth of urban agglomerations. The resulting – and ongoing – societal developments have continuously increased the need for highly detailed, accurate and timely spatial data. This ever-evolving landscape forms the backdrop for examining where UAS mapping is now heading.
The main spatial data acquisition technologies for detailed 3D mapping of sites are based on imaging devices (photogrammetry) and Lidar sensors (laser scanning). The processing software to extract meaningful information from the data is greatly supported by the achievements of the computer vision research community over the last four decades. The major semi-finished products are point clouds. Cameras and Lidar sensors can be mounted on a wide variety of platforms or carriers, including vehicles and aircraft. Platforms operating outdoors, such as manned aircraft and cars, are usually equipped with GNSS and an inertial navigation system (INS) to accurately determine the six exterior orientation parameters of the sensors (3D position and orientation of the sensors in space). To improve reliability of georeferencing, additional sensors are often used such as wheel counters and compasses. The use of ground control points further enhances the geometric accuracy of the data. Thanks to simultaneous location and mapping (SLAM) algorithms, indoor mapping has become possible using trolleys, backpacks or handheld solutions. The decision for a specific platform depends on the application, size of the survey area, severity of disruption to human activities (e.g. interference with train timetables), required accuracy and level of detail, costs, instruments available at the surveying firms and the ability of those firms to communicate the benefits of their solutions to potential customers.
On the flip side of societal developments are the technological advances. The key trend in the evolution of UAS mapping can be summarized as the miniaturization of components. Cameras and Lidar sensors suited for capturing high-quality data are becoming smaller and lighter, propped up by advanced processing software which facilitates the use of calibrated metric cameras and heavy Lidar sensors for precision solutions. Today’s positioning and orientation systems (POS) based on GNSS and INS can be held in the palm of one’s hand. The miniaturization of rotors, electric engines and batteries, in combination with carbon-fibre frames, has enabled the construction of lightweight UASs without compromising air stability. On such systems, camera(s) and Lidar (sensors) can be mounted abreast for the simultaneous capture of images and Lidar point clouds. Concurrent capturing of Lidar point clouds and photogrammetric images has proven to be beneficial for 3D mapping of built-up areas.
As illustrated by the numerous case studies published in GIM International in recent years, the UAS has proven its suitability for many 3D mapping applications, including at archaeological sites, industrial complexes, power stations, open-pit mines and construction sites. The use of UASs for capturing such sites will continue to flourish. Particularly, UAS photogrammetry is routinely used for mapping, inspection and monitoring of such sites. The projects concern individual buildings, small areas of interest and other isolated outdoor sites. Vast areas, such as urban agglomerations, are usually three-dimensionally mapped by selecting one geodata acquisition technology (often aerial photogrammetry) for the entire territory. That means all spots are treated equally. However, it is not always a case of ‘one size fits all’; some spots are more equal than others. Choosing one technology based on the greatest common denominator results in a dataset in which some spots are captured at the right level of detail while others are over-detailed or under-detailed. By complementing a UAS with trolley-based, backpack or handheld mobile mapping systems, under-detailed spots can be captured at the desired level of detail.
The ongoing miniaturization of carriers and sensors in conjunction with SLAM algorithms for positioning and orientation purposes has also made it possible for copters to manoeuvre through indoor spaces. Equipped with cameras and/or laser scanners, they can collect high-density point clouds. The high level of detail and accuracy of the data helps facility managers to inspect their property. It also supports the creation of 3D cadastres, which are aimed at recording the ownership of volumetric parts of buildings and other constructions. Authorities and citizens alike are convinced that wasting fuel and other resources as well as the emission of harmful substances should be minimized through reuse, refurbishment and/or the use of alternatives in pursuit of the circular economy. The main consequence is that sites where humans are active, including agricultural lands and mines, need to be mapped and monitored in ever-greater detail. Within today’s industrial agriculture, for example, the collection of spatial data supports regular inspections to avoid waste of fertilizers, fuel, seeds and water. A UAS is well-suited for capturing such spatial data on a regular basis. When it comes to indoor mapping, UAS and mobile mapping complement rather than compete with one another. For example, if used indoors a UAS could collide with objects or people, causing damage and possibly injuries, making it useless in crowded indoor environments. In such a setting, mobile mapping is a perfect solution. In addition, the two platforms have different perspectives (i.e. view angles): sideways-looking versus image capture from above.
Building information modelling (BIM) plays an essential role in the circularity mindset, since information on the types and quantities of construction materials used is key. Such an information system, which is also needed for the inspection and maintenance of indoor and outdoor spaces, could be called a building materials cadastre.
Ever since the emergence of computers, it seems to have been a rule of thumb that the amount of data acquired by sensors is ten times as much as the processing capacity of computers – so it’s no wonder that so many researchers are throwing themselves into data science and artificial intelligence to speed up the processing of geodata. Another major bottleneck preventing the rapid introduction of UASs in several applications is that many professionals seem reluctant to replace tried-and-tested technology with a novelty that has a non-proven outcome – even though it may be convincingly cheaper and demonstrably more efficient.
There are four essential ingredients determining data quality (i.e. accuracy and detail) in 3D mapping systems: the sensors, the software, the platform and, above all, the survey plan. The design of the survey plan requires thorough knowledge, skills and expertise. This is where the geomatics specialist comes in. Given the strong societal needs for geoinformation outlined above, it is odd that universities in so few countries offer bachelor-level geomatics degrees; at best, the subject is usually on offer at master’s level only. There is a serious risk that society will pay the price for this in the future and be forced to increasingly depend on the less specialized knowledge of the multinational informatics industry.
Author: Mathias Lemmens