Despite invading people’s privacy and falling on the heads of the people, another danger from the drones arises from their rotor blades that can slice the skin easily. However, there is an experimental system which is designed to stop the rotor blades before they can cut the skin. The system is known as Safety Rotor and is being developed by a team from University of Queensland, Australia.
The system uses four lightweight plastic hoops and each one is mounted on one of the drone’s sets of rotors and extend out to surround the rotor blades. The spinning of the rotors causes the hoops to spin with it since they are mounted with a low-friction bearing on the rotor shaft. They do not spin fast like the rotors and can stop any of them independently. If a finger comes near the rotors, it will get hit by the hoop before making a contact with the blade itself. This makes the hoop to stop rotating which is instantly detected by an infrared optical sensor which is mounted below the hoop on the drone’s rotor arm.
The sensor also prompts the microcontroller which is driving the rotor’s motor to apply an electrodynamic braking system. This will stop the blades from spinning in less than 0.06 seconds from the time when the finger touches the hoop. Presently, a complete Safety Rotor setup weighs around 20 gms. It can be retrofitted to an existing drone as well for US$11. It will only obstruct the air flow or will reduce the flight time. If the systems were mass-produced and built into drones, it can cost less than $5 per unit. The team recently presented their Safety Rotor at the 2018 International Conference on Robotics and Automation and is looking for partners which are interested to commercialize the system.