The vision of a drone-filled future involves tiny buzzing pieces of plastic and lithium-ion filling the skies above us. But for that vision to be realized, corporations have to be sure a plummeting drone won’t cause a horrific injury to innocent passersby below. So what actually happens when a drone collides with a human?
It’s a matter that the Alliance for System Safety of UAS through Research Excellence (ASSURE) has sought to reply with an 18 month-long study. Led by the University of Alabama, Hunstville together with Mississippi State University, The National Institute for Aviation Research at Wichita State University and a number of other others, ASSURE’s Phase II Ground Collision study checked out potential injuries arising from collisions between small unmanned aircraft systems (aka consumer drones) and folks.
Researchers not only desired to see what injuries resulted but to develop safety testing methodology and make recommendations to the FAA for rule-making. It’s the one comprehensive science-based study of its kind on the planet.
The Dangers of a Drone Collision
The testing setup for the drone collision experiment.
It sounds potentially terrifying and the videos here don’t look reassuring but ASSURE found that the small, mostly plastic drones are very flexible with loads of elasticity. Contrary to popular opinion, they have a tendency to soak up a big amount of impact energy, says David Arterburn, ASSURE’s principal investigator.
“A typical misconception is that each drone is a rock so when it hits you, it’s going to harm you want a rock.”
ASSURE conducted 512 impact tests and simulations using 16 different vehicles including popular consumer drones like DJI’s Phantom and Mavic Pro in addition to various objects and payloads (batteries, wood blocks) with weights starting from 0.71 to 13.2 lbs. Full anthropomorphic and simplified head-and-neck-only impact tests were done as were Post Mortem Human Surrogate (cadaver) impact tests.
And there is a reason why these videos and photos look just like automotive crash testing. One among the goals of ASSURE is to adapt such proven methodology to business drone flight. In tandem with making recommendations to the FAA, the organization can be searching for global safety standards.
Probably the most common injuries were lacerations, cuts, and bruises. Arterburn says that the inexact science of concussions prevented a practical assessment of the danger of that form of injury. There was just one incident of significant eye damage though ASSURE acknowledges that the rotating blades on ubiquitous quad-copter drones will result in ocular injuries. Amongst its recommendations to the FAA is rotor/blade guards for such drones and development of medical mitigation procedures.
A front view of a fixed-wing drone strikes a test dummy. The study adapted automotive testing methodology to drones. Credit: University of Witchita.
Researchers did the whole lot they may to make sure their testing was controlled, consistent and based on scientific method ASSURE Executive Director, Stephen P. Luxion says.
“We still had loads of variability,” he acknowledges. “Even a quarter-inch offset in a collision sequence could lead to a big reduction in injury to the person.”
But Luxion says the injuries within the report are true center-of-mass collisions, the worst case they may effect in testing. Overall, the outcomes show that fatalities required an almost golden hit. A bigger real-world sample size might change the equation, however the indications are that accidental death-by-drone needs to be fairly rare.
You may think the worst case can be getting struck by considered one of the sharp rotor arms of a quadcopter drone, but researchers found that the drones tended to rotate away from the strike point, taking kinetic energy with them. Most dangerous was being struck by the drone between the rotor arms with the blunt impact of the drone body doing the damage. Drones are inclined to tumble when control is lost and being hit by an upside-down drone did more damage as well.
The underside line is that orientation matters together with speed and weight, which can help illustrate rules for drones flying over crowds of individuals—an absolute necessity if the patron drone industry has any hope of growing.
Trying to find the Holy Grail
A plastic drone’s elasticity can absorb a majority of the impact as seen on this test footage. credit: university of witchita.’
Most of the people is just not alone in being interested in the severity of drone-human collisions. Drone makers were positively ravenous for a study, Arterburn says.
“Firms are really responding to the indisputable fact that they now have clear standards and methodology for testing that may result in actionable design changes they will make to enhance the protection of their products for the general public.”
The explanation is clear. Flying drones over urban and suburban environments is where the cash goes to be made in services from package delivery to pet tracking. It’s called “flight-over-people” within the industry and the principles governing it can affect many businesses.
The knowledge in ASSURE’s report is already having an impact on small drone design. Until recently, speed and payload were top design drivers—now safety is taking primacy.
“[Drone] makers can now evaluate their designs against ASSURE data,” Arterburn says. “That’s a metric they’ve never had before….once you get to the 8 to 10 pound [weight] range, mass and design elasticity begin to mix to make more serious injuries.”
That’s a possible issue for package delivery operators like UPS. The corporate made news with last-mile drone delivery tests in 2017, launching them from its famous brown trucks. UPS tested battery-powered 9.5 pound HorseFly drones with 10 pound payload capability—enough to handle typical residential deliveries. That might put the delivery drone weight at 20 kilos, significantly raising the danger of collision injuries.
One among the important thing findings of ASSURE’s testing was that drone payloads are inclined to have stiffer construction and more mass, increasing injury potential.
“Many payloads do not need the elasticity that the vehicles have due to their construction,” Arterburn says. “Each construction and mass have a job in defining injury potential.” For instance, a half-pound lithium battery poses more risk when carried externally than when enclosed inside a 2.5 pound drone.
Regulations governing the type of payloads, weights, and configurations that delivery drones can carry seem very likely. The potential use of drone parachutes may reduce risk but lots more testing in less controlled conditions shall be needed.
For now, unrestricted drone flight-over-people stays a dream—but it surely’s a dream value chasing.
