Chinese university tackles rotor failure in drones with algorithm

BEIJING, Jan. 16 (Xinhua) -- For a drone with four propellers, also known as a quadcopter, the failure of one motor is a big problem. With only three rotors working, the drone loses stability and inevitably crashes unless an emergency control strategy sets in.

Researchers at Beihang University, specializing in aeronautical and astronautical research, have now found a solution to this problem: They designed an algorithm to stabilize the drone and keep it flying autonomously after one, two or even three rotors suddenly give out.

"When one rotor fails, the drone begins to spin on itself like a gyro," said lead researcher Quan Quan, a professor at the university.

This high-speed rotational motion will cause controllers to fail. Once it starts spinning, the drone can no longer estimate its position in the sky and eventually crashes.

In this new study, the problem was ingeniously tackled by Quan's team, who eschewed the conventional approach of controller switching and instead employed a sophisticated technique known as "uniform passive fault-tolerant control."

The algorithm enables the onboard computer to control the drone as it flies and spins, even if three propellers fail.

"The algorithm we have developed enables a functional propeller to generate the entire lift of the drone after it starts spinning -- it's akin to engaging in a game of table tennis where an adept player possesses the ability to serve, dash across to the opposing side, and skillfully catch the ball, thus seamlessly completing the game single-handedly," Quan explained to Xinhua.

The research findings appeared in the international journal IEEE Transactions on Robotics. It also featured a video showcasing the successful execution of outdoor experiments. During these experiments, the quadcopter demonstrated its ability to maintain safe flight even when faced with one, two or three rotor failures.

Ke Chenxu, a primary participant in the research and a Ph.D. student at the university, said that the method can be applied to multi-rotor drones with six or eight rotors.

According to the researchers, the study holds massive significance, as quadcopters are increasingly ubiquitous, spanning from fire rescue operations to package delivery services. They believe this fault-tolerant control method has the potential to enhance quadrotor flight safety across all domains.