Controlled flight of a multicopter experiencing a failure affecting an effector

Patent metadata

Field	Value
Publication number	US-10946950-B2
Application number	US-202016742506-A
Country	US
Kind code	B2
Filing date	Jan 14, 2020
Priority date	Jun 9, 2013
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

According to a first aspect of the invention, there is provided a method for operating a multicopter experiencing a failure during flight, the multicopter comprising a body, and at least four effectors attached to the body, each operable to produce both a torque and a thrust force which can cause the multicopter to fly when not experiencing said failure. The method may comprise the step of identifying a failure wherein the failure affects the torque and/or thrust force produced by an effector, and in response to identifying a failure carrying out the following steps, (1) computing an estimate of the orientation of a primary axis of said body with respect to a predefined reference frame, wherein said primary axis is an axis about which said multicopter rotates when flying, (2) computing an estimate of the angular velocity of said multicopter, (3) controlling one or more of said at least four effectors based on said estimate of the orientation of the primary axis of said body with respect to said predefined reference frame and said estimate of the angular velocity of the multicopter. The step of controlling one or more of said at least tour effectors may be performed such that (a) said one or more effectors collectively produce a torque along said primary axis and a torque perpendicular to said primary axis, wherein (i) the torque along said primary axis causes said multicopter to rotate about said primary axis, and (ii) the torque perpendicular to said primary axis causes said multicopter to move such that the orientation of said primary axis converges to a target orientation with respect to said predefined reference frame, and (b) such that said one or more effectors individually produce a thrust force along said primary axis.

First claim

The invention claimed is:

1. A method for operating a multicopter experiencing a failure during flight, the multicopter comprising,
a body; and
at least four effectors attached to the body, each configured to produce both a torque and a thrust force which can cause the multicopter to fly,

the method comprising the steps of,
when a failure has occurred in one or more of said at least four effectors resulting in a decrease in the torque and/or the thrust force produced by said one or more of said at least four effectors in which the failure has occurred, determining the decrease of torque and/or thrust force produced by said one or more of said at least four effectors in which the failure has occurred;
using a control unit to control one or more of said at least four effectors, based on, the determined decrease of torque and/or thrust force produced by said one or more of said at least four effectors in which the failure has occurred, the orientation of a primary axis of said body with respect to a predefined reference frame, and the angular velocity of said multicopter, such that said one or more effectors collectively produce a torque perpendicular to said primary axis, wherein the torque perpendicular to said primary axis causes said multicopter to move such that the orientation of said primary axis converges to a target orientation with respect to said predefined reference frame, and such that each of said one or more effectors individually produces a thrust force along said primary axis.

2. A method according to claim 1 comprising a step of identifying the failure that has occurred, and wherein said steps of determining the decrease of torque and/or thrust force produced by said one or more of said at least four effectors in which the failure has occurred, and, using a control unit to control one or more of said at least four effectors, are carried out in response to identifying the failure.

3. A method according to claim 2 wherein the step of identifying a failure is carried out using an evaluation unit which can communicate with the control unit.

4. A method according to claim 1 wherein the step of determining the decrease of torque and/or thrust force produced by said one or more of said at least four effectors in which the failure has occurred is carried out by an evaluation unit which can communicate with the control unit.

5. A method according to claim 2 wherein the step of identifying a failure comprises identifying a failure which results in a decrease of the torque and/or thrust force produced by at least one of said at least four effectors by an amount greater than 20%; or
wherein the step of identifying a failure comprises identifying a failure which results in a decrease of the torque and/or thrust force produced by at least one of said at least four effectors by an amount greater than 50%; or
wherein the step of identifying a failure comprises identifying a failure which results in a decrease of the torque and/or thrust force produced by at least one of said at least four effectors by an amount greater than 80%.

6. A method according to claim 2 wherein the step of identifying a failure comprises identifying a failure which results in the a least one of said at least four effectors producing no torque and/or thrust force.

7. A method according to claim 2 wherein the step of identifying a failure, is carried out by an evaluation unit based on data representative of at least one of (a) one or more variables of a plurality of variables of one or more of said at least four effectors, and/or (b) data representative of the motion of said multi copier.

8. A method according to claim 7 wherein the plurality of variables of one or more of said at least four effectors comprises at least one of: rotational speed; voltage; electric current; fuel flow; motor torque; mass flow; and/or power.

9. A method according to claim 7 wherein said data representative of the motion of said multicopter, comprises one or more of: an orientation of said multicopter; an angular velocity of said multicopter; an operational state of one or more of said at least four effectors of said multicopter; an acceleration of said multicopter; a translational velocity of said multicopter; and/or a position of said multicopter.

10. A method according to claim 2 , wherein in response to said identifying said failure, using a control unit to control one or more of said at least four effectors, such that said one or more effectors further collectively produce a torque along said primary axis, which causes said multicopter to rotate about said primary axis.

11. A method according to claim 10 wherein said torque along said primary axis causes said multicopter to rotate about said primary axis at a speed greater than 0.5 revolutions per second.

12. A method according to claim 1 , comprising using the control unit to carry out steps of, computing said estimate of the orientation of the primary axis of said body with respect to a predefined reference frame; and computing said estimate of the angular velocity of said multicopter.

13. A method according to claim 1 wherein said primary axis is an axis aligned with a sum of thrust forces produced by said one or more of said at least four effectors over a predefined time with respect to the predefined reference frame.

Assignees

• Eth Zuerich

Inventors

• Mueller Mark W
• Lupashin Sergei
• D'Andrea Raffaello
• Waibel Markus

Classifications

• B64U2201/20

  Remote controls · CPC title

• B64U2201/10

  autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS] · CPC title

• B64U2101/30

  for imaging, photography or videography · CPC title

• G05D1/617

  Safety or protection, e.g. defining protection zones around obstacles or avoiding hazards (arrangements for controlling the position or course of two or more vehicles for avoiding collisions therebetween G05D1/693; arrangements for reacting to or preventing system or operator failure G05D1/80) · CPC title

• B64U40/10

  for adjusting control surfaces or rotors · CPC title