Rotary-wing drone provided with a video camera delivering stabilized sequences of images

1. A rotary-wing drone ( 10 ), comprising:

a camera ( 14 ), including a hemispherical-field lens of a fisheye type pointing to a fixed direction (Δ) with respect to a drone body, as well as a digital sensor acquiring an image (I) formed by a lens and delivering raw pixel data;

an image processing means ( 156 ), receiving as an input the raw pixel data and delivering as an output rectified pixel data, compensated for geometric distortions introduced by the fisheye lens;

means ( 158 ) for delivering as an output rectified pixel data, for transmission to a display or a video-recording device;

an inertial unit ( 154 ), adapted to measure Euler angles (φ,θ,ψ) characterizing an attitude of the drone body with respect to an absolute terrestrial reference system; and

a control means ( 152 ), receiving as an input at least one Euler angle delivered by an inertial unit ( 154 ), and adapted to window the raw pixel data delivered as an output by a delivery means as a function of changes of attitude of the drone detected by the inertial unit,

characterized in that:

the digital sensor is a scanning sensor delivering line by line said raw pixel data;

the drone further includes extraction means ( 152 ), receiving as an input a selection signal defining over the digital sensor a position of a capturing area (ZC) of reduced size, and delivering as an output said raw pixel data, which correspond to the capture area of reduced size;

a servo-control means ( 152 ) are means adapted to dynamically modify said selection signal in a direction opposite to that of a change of attitude of the drone detected by the inertial unit and characterized by a corresponding variation of said at least one Euler angle; and

said image processing means ( 156 ) receive as an input the raw pixel data delivered by an extraction means.

2. The drone of claim 1 , wherein the servo-control means are adapted to modify the selection signal so that the raw pixel data delivered by the extraction means correspond to an image centered on a horizon, or centered on a fixed orientation with respect to the horizon.

3. The drone of claim 1 , wherein the camera is mounted in the drone so that a frame scanning direction (D B ) of the digital sensor is oriented parallel to a pitch angle ( 22 ) of the drone.

4. The drone of claim 1 , wherein said at least one Euler angle is a pitch angle (φ) of the drone, and the servo-control means are adapted to modify the selection signal so as to translate the capture area in a first direction, parallel to a main axis of the digital sensor.

5. The drone of claim 4 , wherein said at least one Euler angle is a yaw angle (ψ) of the drone, and the servo-control means are adapted to modify the selection signal so as to translate the capture area in a second direction, perpendicular to said first direction.

6. The drone of claim 1 , wherein the image processing means ( 156 ) are adapted to apply to each line (l i ) of the sensor an additional correction to compensate for the relative displacements of pixels from one line to the following one, induced by rotations of the drone about a yaw, pitch or roll axis.

7. The drone of claim 6 , wherein:

the camera ( 14 ) is a camera of a rolling shutter type delivering video data line by line;

the camera ( 14 ) and gyrometric sensors ( 102 ) of the inertial unit ( 154 ) are piloted by a common clock ( 160 ); and

an acquisition rate (F gyro ) of the gyrometric sensors ( 102 ) is a multiple (K) of a video data delivery rate (F cam ) of the camera ( 14 ).

8. The drone of claim 7 , further comprising a hardware circuit ( 170 ) adapted to:

compare a signal (S gyro ) delivered by the gyrometric sensors ( 102 ) with the signal (S cam ) delivered by the camera ( 14 );

determine a phase-shift value between these respective signals; and

apply this phase-shift value to the image processing means ( 156 ) so as to trigger in a synchronous manner said additional correction applied to each line of the digital sensor to compensate for the relative displacements of the pixels from one line to the following one.