The folks at Spectrum[1] have found a truly cool project for quadcopter pilots. It’s a spinning sensor that will stop the rotors if your finger gets too close to the blades, thereby preventing you – or your kids – from getting cut.
Researchers at the University of Queensland in Brisbane, Australia created so-called Safety Rotor to help prevent accidents with more powerful quadrotor drones. The system constantly senses for a “finger” – in this case a hot dog – and then slams the rotor to a stop within 0.077 seconds. A cage around the propellers spins more slowly than the propellers and is constantly on the lookout for biological material approaching the blades.
The measured latency [of the Safety Rotor’s braking response] was 0.0118 seconds from the triggering event to start of rotor deceleration. The rotor required a further 0.0474 s to come to a complete stop. Ninety percent of the rotational kinetic energy of the rotor (as computed from angular velocity) was dissipated within 0.0216 s of triggering, and 99 percent of the rotational kinetic energy of the rotor was dissipated within 0.032 s.
The safety functionality of the safety system was tested on the bench using a processed meat “finger” proxy to trigger the hoop, and also applied to an open rotor (without hoop) for comparison. The rotor was spun at hover speed (1100 rads−1) and the finger proxy was introduced into the hoop at 0.36 ms−1 … The rotor and finger motion were captured using a shutter speed of 480 Hz. The rotor came to a stop within 0.077 s, with only light marks on the finger proxy from the impact of the hoop. The rotor was completely stopped by the...