Algorithm lets quadcopters keep flying on three or less propellers

Algorithm lets quadcopters kee...
A quadcopter running the algorithm is able to remain in control, even after losing one propeller
A quadcopter running the algorithm is able to remain in control, even after losing one propeller
View 1 Image
A quadcopter running the algorithm is able to remain in control, even after losing one propeller
A quadcopter running the algorithm is able to remain in control, even after losing one propeller

Whether it's for Amazon-purchased goods, text books or defibrillators, unmanned multicopters are increasingly being considered for use as delivery vehicles. Given that this would involve their flying over heavily-populated areas, however, many people are rightly concerned about the aircraft malfunctioning and crashing down onto someone below. That's why researchers at ETH Zurich have created a control algorithm that allows any quadcopter to keep flying, even if it loses multiple motors or propellers.

Because of the risk of crashes, most of the currently-proposed delivery drones are hexa- or octocopters. With their six or eight motors/propellers, they're already able to remain airborne if one of those should konk out. With all of that extra hardware, however, they're also larger, heavier, more complex, and thus less efficient than quadcopters.

The ETH algorithm can be added to the control system of existing quadcopters, and requires no physical changes or additions to the aircraft.

When the software detects that one or more of the propellers has stopped working – either because it's come off, or due to motor failure – it initially uses the remaining props to put the drone in a hovering horizontal spin. Then, by selectively altering the thrust of each propeller, it steers the quadcopter by tilting the angle of its rotation, and eases it down to a controlled landing.

The algorithm reportedly works even if only one prop is operational. A quadcopter using the technology to land on three propellers can be seen in the video below.

Source: ETH Zurich

Quadrocopter failsafe algorithm: recovery after propeller loss

Stephen Colbourne
I thought a quad-copter which had wings would be much more efficient, reliable and faster. This could be simply by having the aircraft rotate 90 degrees. An example of a full size tiltwing example is the Ryan X-13 Vertijet
Mark Neal
@stephen See quadshot or flexrotor for transition craft.
Amazing how something so obvious... isn't (until after you've seen it!)
Jay Finke
Talk about Mr toad's wild ride
I have been toying with a quad-copter design which incorporates rotors in wings with a lifting body cockpit. in my plan the stern rotors will swivel 90degs' and be pushers while the forward rotors will remain in the fixed wing lifting position. the rear rotors that swivel can also rotate to a negative or revers position for a very fast stop. I also thought a steerable ( safety ) 'glide parachute shoot' and /or under carriage air bags, would be a good idea for feathered prop , power failure. a passenger size model would require a jet power plant driving central generators. its fun to draw on an it would be a hoot to fly!
This is similar to how a single bladed helicopter flies.
As long as the period of precession of the craft is high enough to overcome the period of instability (remove the instability from the model) it works fantasticly...
They should be able to get it to work so well that the mission could still be completed at reduced performance, or the craft return back to base...
Great to see the recovery phase, the aircraft went out of control and recovered, a little like a fly or butterfly does in the real world when hit with a string gust of wind (though the mechanism is totally different).
What kind of failsafe do they have on e-volo multicopters? They will have to have something as good or better.