Volitant vehicle rotating about an axis and method for controlling the same

Patent metadata

Field	Value
Publication number	US-10464661-B2
Application number	US-201414893851-A
Country	US
Kind code	B2
Filing date	Jun 5, 2014
Priority date	Jun 9, 2013
Publication date	Nov 5, 2019
Grant date	Nov 5, 2019

Abstract

According to a first aspect of the invention, there is provided a volitant vehicle comprising, a body (112), a control unit being configured to compute an estimate of the orientation of a primary axis (130) of said body with respect to a predefined reference frame, wherein said primary axis is an axis about which said vehicle rotates when flying; and at least one propeller (104) attacked to the body, wherein each of said at least one propeller has an axis of rotation (110) which is fixed with respect to said body, is configured to simultaneously produce a thrust force and a torque, said thrust force having a component along the primary axis, said torque having a component along the primary axis constructively contributing to the vehicle rotating about said primary axis, said torque having a component perpendicular to the primary axis, and all of said at least one propeller rotate with the same handedness about their respective thrust forces.

First claim

The invention claimed is:

1. A volitant vehicle comprising,
(a) a body,
(b) a control unit being configured to
i. compute 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 vehicle rotates when flying; and

(c) one or more propellers attached to the body, wherein
each of said one or more propellers
A. has an axis of rotation that is fixed with respect to said body,
B. wherein said one or more propellers is/are configured so that, during use said one or more propellers produce all thrust force necessary to lift the body, and all torque force that rotates the body about said primary axis,
said thrust force having a component along said primary axis,
said torque having a component along the primary axis constructively contributing to the vehicle rotating about said primary axis,
said torque having a component perpendicular to said primary axis, and

wherein all of said one or more propellers that contribute to said thrust force and torque force that lift and rotate said body during use, rotate with the same handedness about their respective thrust forces, and each of said one or more propellers is arranged such that the axis of rotation of each of said one or more propellers is substantially parallel to the primary axis,
wherein said control unit is further configured to compute said target orientation of said primary axis using said target acceleration of said volitant vehicle such that said target orientation is aligned with the vector sum of said target acceleration and the gravitational acceleration,
wherein said control unit is configured to compute said target orientation of said primary axis using said target acceleration of said volitant vehicle such that said target orientation is aligned with the vector sum of said target acceleration and the gravitational acceleration, using the equation ñ=(a−g)/∥a−g∥, wherein the vector a represents said target acceleration and the vector g represents the gravitational acceleration, and the vector ñ represents said target orientation, and ∥·∥ represents the Euclidean norm of a vector.

2. A volitant vehicle according to claim 1 , wherein said control unit is further configured to control all of said one or more propellers such that all of said one or more propellers collectively
produce a torque perpendicular to said primary axis causing said vehicle to move such that the orientation of said primary axis converges to a target orientation with respect to said predefined reference frame.

3. A volitant vehicle according to claim 1 wherein
each of said one or more propellers is configured to contribute to a resultant thrust force acting on said vehicle, by having each of said one or more propellers attached to the body such that
the thrust force having said component along the primary axis constructively, contributes to the component of the resultant thrust force along the primary axis.

4. A volitant vehicle according to claim 2 , wherein the thrust force of each of said one or more propellers contributes a fraction of at least 0.5/N to the component of the resultant thrust force along the primary axis when the orientation of the primary axis has converged, where N is the number of said one or more propellers.

5. A volitant vehicle according to claim 3 , wherein, for each of said one or more propellers,
a) produce the thrust force having said component along the primary axis constructively contributing to the component of the resultant thrust force along the primary axis,
b) and produce a torque with said component along the primary axis constructively contributing to the vehicle rotating about said primary axis when producing said thrust force, and
said component perpendicular to the primary axis,
achieved through the mechanical arrangement of said axis of rotation.

6. A volitant vehicle according to claim 5 , wherein
said mechanical arrangement comprises attaching each of the one or more propellers
to an effector,
said effector being rigidly attached to said body.

7. A volitant vehicle according to claim 2 , wherein, for each of the one or more propellers, the torque comprises
a) the force acting at a distance from the centre of mass of the vehicle, b) a reaction torque opposing the propeller's sense of rotation, caused by drag acting on the propeller blades moving through the air.

8. A volitant vehicle according to claim 2 , wherein, for each of the one or more propellers, at least 50% of the torque component perpendicular the primary axis is due to the thrust force acting at a distance from the centre of mass of the vehicle.

9. A volitant vehicle according to claim 1 , furthermore comprising
an input unit for receiving data from sensors and/or users,
a sensing unit for measuring data representative of the motion of said volitant vehicle, and
an evaluation unit operationally connected to said sensing and/or input unit,
wherein
a) said evaluation unit is configured to provide data representative of the motion of said volitant vehicle based on said data received from said sensing unit, and
b) said evaluation unit is operationally connected to said control unit to provide data, and
c) said control unit s structured and arranged to perform said computing of an estimate of the orientation of the primary axis based on said data provided by said evaluation unit.

10. The volitant vehicle according to claim 1 , wherein said control unit is configured such that, during use, the control unit controls said one or more propellers to collectively produce a torque along said primary axis to cause said volitant vehicle to rotate about said primary axis at a speed greater than 0.5 revolutions per second.

11. The volitant vehicle according to claim 1 , wherein said control unit is further structured and arranged
a) to compute a target acceleration for said volitant vehicle based on said data provided by said evaluation unit, and
b) to use said target acceleration to compute said target orientation of said primary axis for said volitant vehicle, and
c) to send said control signals to said effectors such that said one or more propellers is controlled such that the thrust collectively produced by said one or more propellers accelerates said volitant vehicle at said target acceleration.

12. The volitant vehicle according to claim 1 , wherein said control unit is further configured
to compute a target thrust force magnitude based on said data provided by said evaluation unit, and
to send said control signals to said effectors such that the magnitude of the resultant thrust force over a predefined period equals the target thrust force magnitude.

13. The volitant vehicle according to claim 12 , wherein said control unit is further configured to compute said target thrust force magnitude using said target acceleration of said volitant vehicle by,
computing said target acceleration,
computing said target thrust force magnitude as
f des =m∥a−g∥

wherein f des represents the target thrust force magnitude, ∥·∥ represents the Euclidean norm of a vector, a represents the said target acceleration, g represents the acceleration due to gravity and in represents the mass of said volitant vehicle.

14. The volitant vehicle of claim 1 , said volitant vehicle further comprising a sensor that is operationally connected to said sensing unit and structured and arranged
to detect data representative of the motion of the volitant vehicle, and
to provide said data representative of the motion of the volitant vehicle to said sensing unit.

Assignees

• Eth Zuerich

Inventors

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

Classifications

• B64U2101/30

  for imaging, photography or videography · 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

• B64U2201/20

  Remote controls · CPC title

• B64D45/00

  Aircraft indicators or protectors not otherwise provided for · CPC title

• B64C27/32

  Rotors · CPC title