Researchers invent quadrotor safety system to protect fingers

Anyone who has been around the quadcopters on the market today has probably wondered just how bad it would hurt to get your finger caught in the whirring propellers. The answer is a lot, in fact, if the quadrotor is large enough you could lose that finger. Researchers at the University of Queensland in Brisbane, Australia have come up with a way to make quadrotor drones safer.

The challenge for safety systems for quadrotors aircraft now is one of weight and complexity. Too much weight lowers the payload and flight time while complex systems tend to break. The new system the researchers developed is called the Safety Rotor.

The idea behind the system is simple, a plastic hoop is added to the rotor that spins around the plane of the rotor itself. The idea is that the spinning hoop would contact anything that might hit the rotor first. When that spinning hoop registers contact its puts the brakes on the rotor.

The rotor won’t completely stop so the drone stays aloft, but it will slow the rotor enough to prevent the loss of a finger. The hoop spin is driven by the slight friction against the rotor hub that makes it rotate at a rate of a few tens of Hertz. That is fast enough to detect obstacles but slow enough that the hoop itself poses no danger.

The brake is electromagnetic and functions by shortening the motor inputs to turn into a generator instead. The current generated by the motor opposes the direction that the propeller is rotating. The faster the motor rotates, the more current it generates. The system will cost about $14 to add safety rotors to an average drone and add 22 grams of weight. Not much of a trade-off for the safety the system provides especially when kids are around.

SOURCE: Spectrum