Robohub.org
 

Quadrocopter failsafe algorithm: Recovery after propeller loss

by
04 March 2014



share this:
Drone-Failsafe-Algorithm

UPDATE 04/03/2014:

In this video update, we show that a quadrocopter can be safely piloted by hand after a motor fails, without the aid of a motion capture system. This follows our previous video, where we demonstrated how a complete propeller failure can be automatically detected, and that a quadrocopter can still maintain stable flight despite the complete loss of a propeller. 

In the earlier video, we relied on an external motion capture system to measure the quadrocopter’s position and orientation.  By moving more of the algorithm onto the vehicle, the quadrocopter can now be piloted by hand after the failure. The algorithm is executed on the quadrocopter’s onboard micro-controller, and the only sensors required are the quadrocopter’s angular rate gyroscopes. We use blinking LEDs, mounted on the quadrocopter’s arms, to indicate a virtual yaw angle, so that the pilot can control the vehicle with the same remote control commands after the failure. As an alternative to the LED system, an onboard magnetometer could be used to track the vehicle’s yaw angle. Alternatively, by using more sophisticated algorithms, the system could be made to work using only the rate gyroscopes.

ORIGINAL STORY 02/12/2013

The video in this article shows an automatic failsafe algorithm that allows a quadrocopter to gracefully cope with the loss of a propeller. The propeller was mounted without a nut, and thus eventually vibrates itself loose. The failure is detected automatically by the system, after which the vehicle recovers and returns to its original position. The vehicle finally executes a controlled, soft landing, on a user’s command.

The failsafe controller uses only hardware that is readily available on a standard quadrocopter, and could thus be implemented as an algorithmic-only upgrade to existing systems. Until now, the only way a multicopter could survive the loss of a propeller (or motor), is by having redundancy (e.g. hexacopters, octocopters). However, this redundancy comes at the cost of additional structural weight, reducing the vehicle’s useful payload. Using this technology, (more efficient) quadrocopters can be used in safety critical applications, because they still have the ability to gracefully recover from a motor/propeller failure.

Failsafe_algorithm_sequence
(A) shows the quadrocopter in normal operation. In (B) the propeller detaches due to vibrations, and the quadrocopter starts pitching over in (C) – (E). In (F) the vehicle has regained control, and is flying stably.

The key functionality of the failsafe controller is a novel algorithm that I developed as part of my doctoral research at the Institute for Dynamic Systems and Control at ETH Zurich. This new approach allows such a vehicle to remain in flight despite the loss of one, two, or even three propellers. Having lost one (or more) propellers, the vehicle enters a continuous rotation — we then control the direction of this axis of rotation, and the total thrust that the vehicle produces, allowing us to control the vehicle’s acceleration and thus position.

Even if the vehicle can no longer produce sufficient thrust to support its own weight, this technology would still be useful: one could, for example, try to minimize the multicopter’s velocity when it hits the ground, or steer the multicopter away from dangerous situations such as water, or people on the ground.

This control approach can also be applied to design novel flying vehicles — we will be releasing some related results soon.

This technology is patent pending.

For more information, have a look at the Flying Machine Arena website, the IDSC research page, or just post your question in the comments below.

 

If you liked this article, you may also be interested in:

See all the latest robotics news on Robohub, or sign up for our weekly newsletter.



tags: , , , , , , , , , , , , , , , ,


Mark Mueller is a researcher at ETH Zurich's Flying Machine Arena.
Mark Mueller is a researcher at ETH Zurich's Flying Machine Arena.





Related posts :



Unable to attend #ICRA2022 for accessibility issues? Or just curious to see robots?

There are many things that can make it difficult to attend an in person conference in the United States and so the ICRA Organizing Committee, the IEEE Robotics and Automation Society and OhmniLabs would like to help you attend ICRA virtually.
17 May 2022, by
ep.

350

podcast

Duckietown Competition Spotlight, with Dr Liam Paull

Dr. Liam Paull, cofounder of the Duckietown competition talks about the only robotics competition where Rubber Duckies are the passengers on an autonomous driving track.
17 May 2022, by

Designing societally beneficial Reinforcement Learning (RL) systems

In this post, we aim to illustrate the different modalities harms can take when augmented with the temporal axis of RL. To combat these novel societal risks, we also propose a new kind of documentation for dynamic Machine Learning systems which aims to assess and monitor these risks both before and after deployment.
15 May 2022, by

Innovative ‘smart socks’ could help millions living with dementia

‘Smart socks’ that track rising distress in the wearer could improve the wellbeing of millions of people with dementia, non-verbal autism and other conditions that affect communication.
13 May 2022, by

Swiss Robotics Day showcases innovations and collaborations between academia and industry

The 2021 Swiss Robotics Day marked the beginning of NCCR Robotics’s final year. The project, launched in 2010, is on track to meet all its scientific goals in the three areas of wearable, rescue and educational robotics, while continuing to focus on supporting spin-offs, advancing robotics education and improving equality of opportunities for all robotics researchers.
10 May 2022, by

Afreez Gan: Open Source Robot Dog, Kickstarter, and Home Robots | Sense Think Act Podcast #18

In this episode, Audrow Nash speaks to Afreez Gan, who is the founder and CEO of MangDang; MangDang is a Chinese startup that makes Minipupper, an open source robot dog that uses the Robot Operating S...





©2021 - ROBOTS Association


 












©2021 - ROBOTS Association