WO2016146704A1

WO2016146704A1 - Device and method for panoramic imaging

Info

Publication number: WO2016146704A1
Application number: PCT/EP2016/055719
Authority: WO
Inventors: Gilles AUBRY; Vincent LEBOUCHER; Thierry CAMPOS
Original assignee: Hgh Systemes Infrarouges
Priority date: 2015-03-17
Filing date: 2016-03-16
Publication date: 2016-09-22
Also published as: FR3033905A1; FR3033905B1

Abstract

The present invention relates to a compact panoramic imaging device having a high resolution and high cadence (100), comprising: a detector (51), arranged to acquire an individual image of an environment (52); a motor (4), arranged to rotate the detector around an axis of rotation (16) of the motor, the motor being arranged to rotate the detector in direct drive mode; control means (6, 8), arranged to control the rotation of the detector around the axis of rotation of the motor according to at least one cycle of successive imaging phases and jump phases, in such a way that during each imaging phase the detector is fixed and does not turn around the axis of rotation of the motor, and acquires an individual image of the environment, and each jump phase comprises an acceleration phase of the detector around the axis of rotation of the motor followed by a deceleration phase of the detector around the axis of rotation of the motor.

Description

"Device and panoramic imaging method"

Technical area

The present invention relates to an imaging device and method.

Such a device allows a user to make a panoramic image almost in real time. The field of the invention is more particularly, but in a nonlimiting manner, that of:

- security: triggering an alarm and / or monitoring threats from movements in the image or the abnormal presence of objects, detection and monitoring of an abnormal approach of pedestrians, vehicles, drones, aircraft, helicopters , boats ... securing sensitive sites or installations (ports, airports, nuclear power stations, infrastructure network nodes, border or military zone surveillance), or

- mobile navigation and steering assistance, where peripheral vision is useful in complex environments. State of the art

Panoramic image acquisition systems are known by rotating a camera.

Among these systems, there is known a first family of systems for which the acquisition unit (or "camera") is rotated at a constant speed, as for example in the case of patent FR 2 947 132. In fact, when the moment of inertia of the elements to be rotated (including the camera) is important, it is not realistic for the skilled person, technically and economically, to proceed by acceleration / stop to move the acquisition unit between two angular positions held fixed the time of the image taking, while respecting a global rate of acquisition of the panoramic image that remains compatible with operational constraints (constraints of low vibration and acquisition "in real time" ). The acquisition unit as a whole is then maintained in constant and uniform rotation, this type of movement does not involve efforts or important couples. To maintain the fixed line of sight in the repository of the scene, it is then resorted to a counter-scanning device. This subassembly, integrated in the moving part of the system, compensates for the main rotational movement by generating an opposite relative rotation of the optical axis. Such a system is however not very compact and relatively expensive.

Among these systems, there is also known a second family of systems for which the acquisition unit (or the camera) is rotated at a non-constant speed, as for example in the case of patent WO 2013/109976. successive units of the acquisition unit are defined by the geometry of a cam. This system does not meet all the requirements for a compact, unobtrusive and reliable panoramic surveillance device, as it does not offer implementation flexibility that allows optimal use in the largest number of operational scenarios.

The object of the present invention is to provide a device or panoramic imaging method which is more compact and less expensive than the systems of the first family, but which at the same time has a greater flexibility of implementation than the systems of the second family for use in a larger number of operational scenarios.

Presentation of the invention

This objective is achieved with an imaging device, comprising: a detector, arranged to acquire an individual image of an environment by converting a light flux coming from the environment into an electrical signal,

a motor, arranged to drive the detector in rotation about an axis of rotation of the motor, the motor being arranged to drive the detector in rotation in direct drive mode, the device according to the invention not comprising, between the motor and the detector, of intermediate piece movable in rotation about an axis parallel to the axis of rotation of the motor, control means, arranged to control the rotation of the detector around the axis of rotation of the motor according to at least one cycle of imaging phases and successive jump phases (each cycle preferably having a duration of less than 2, 5 seconds, which preferably corresponds to the maximum time to cover a full rotation of 360 °), so that:

during each imaging phase, the detector is fixed and does not rotate around the axis of rotation of the motor, and makes an acquisition of an individual image of the environment, and

each jump phase comprises a phase of acceleration of the detector around the axis of rotation of the motor and then a phase of deceleration of the detector around the axis of rotation of the motor.

The motor is preferably arranged to drive the detector in rotation in direct drive mode, the device according to the invention does not comprise, between the motor and the detector, an intermediate piece movable in rotation about an axis parallel to the axis of rotation of the motor or any other degree of freedom in rotation or in translation.

In other words, none of the parts connecting the motor to the detector is rotatable about an axis parallel to the axis of rotation of the motor (or any other degree of freedom in rotation or in translation).

Each jump phase may comprise an acceleration phase of the constant acceleration sensor around the axis of rotation of the motor and then a deceleration phase of the constant deceleration detector around the axis of rotation of the engine. In this case, the constant acceleration is preferably equal, in absolute value, to the constant deceleration.

The detector may be an uncooled thermal infrared detector.

The detector may be a bolometric detector, preferably microbolometric type.

The detector may comprise a matrix of pixels. Each pixel preferably has an angular resolution around the axis of rotation of the motor, less than 2.5 mrad (preferably less than 2.3 mrad) or even less than 0.8 mrad (preferably less than 0.7 mrad).

The motor is preferably a brushless motor.

The device according to the invention may furthermore comprise means for constructing at least one panoramic image by assembling several individual images acquired by the detector during different imaging phases of a cycle of imaging phases and jump phases. each of these assembled individual images being derived from an imaging phase distinct from the imaging phases from which the other individual images assembled are derived. The means for constructing at least one panoramic image can be arranged:

to construct a complete panoramic image imaging 360 ° around the device by assembling several individual images acquired by the detector during different imaging phases of a cycle of imaging phases and jump phases, and / or

- to build several sectorial panoramic images (of identical or various widths) imagining distinct zones of the environment distributed at 360 ° around the device by assembling several individual images acquired by the detector during different phases of imaging of a cycle of imaging phases and jump phases.

The control means are preferably arranged to control a rotation of the detector around the axis of rotation of the motor in less than 2.5 seconds for the acquisition of all the individual images necessary to construct the complete panoramic image or the images. sectoral panoramas.

The control means are preferably arranged to control the rotation of the detector around the axis of rotation of the engine according to several cycles of imaging phases and jump phases, and in a return phase between each pair of successive cycles, so that during each return phase the detector rotates about the axis of rotation of the motor in a direction of rotation opposite to a direction of rotation to be traveled during the jump phases. The device according to the invention is preferably arranged so that, for each cycle of imaging phases and jumping phases, the detector makes at most one complete revolution rotation about the axis of rotation of the motor (preferably less than a full revolution of rotation about the axis of rotation of the motor).

The device according to the invention may comprise an electric wire connection between the detector and a part of the device according to the invention arranged to remain stationary during the jumping phases, the wire link comprising a sheet of wires whose one end is secured to the detector and the other is secured to the immobile part, this sheet of wire being located:

distributed between two arcs of circles, each circular arc being located in a disk-shaped surface perpendicular to the axis of rotation of the motor, so that by traversing a path along the sheet from the still part towards the detector:

o it rotates about the axis of rotation of the motor in a first direction of rotation when traversing this path on one of the arcs of the circle, and

o it rotates about the axis of rotation of the motor in a second direction of rotation opposite to the first direction of rotation when traversing this path on the other arc,

- On a loop connecting the two circular arcs, said loop preferably having a radius of curvature centered on an axis perpendicular to the axis of rotation of the motor.

The sheet of son is preferably arranged so that the distribution between the two circular arcs passes from a minimum of distribution on one of the arcs of circle to a maximum of distribution on this same arc when the detector makes less than two turns 360 ° around the axis of rotation of the engine (or preferably a 360 ° rotation or less of a 360 ° revolution around the axis of rotation of the engine) from a reference angular position . The angular reference position of the detector around the axis of rotation of the motor is preferably the position at which the detector returns at the end of each return phase.

The device according to the invention preferably has a mass of less than 2 kilograms. During each acceleration phase and each deceleration phase, the acceleration and deceleration are preferably greater, in absolute value, at 200 rad / s ² and / or less than 2000 rad / s ² .

The motor preferably has a torque greater than 0.01 Nm and / or less than 0.5 Nm.

According to yet another aspect of the invention, there is provided an imaging method, preferably implemented in a device according to the invention, and comprising:

a rotation drive, by a motor, of a detector around an axis of rotation of the motor, the detector being rotated in the direct drive mode, so that there is not, between the motor and the detector, an intermediate piece movable in rotation about an axis parallel to the axis of rotation of the motor, the detector being arranged to acquire an individual image of an environment by converting a stream light coming from the environment into an electrical signal,

a control, by control means, of the rotation of the detector around the axis of rotation of the motor according to at least one cycle of imaging phases and successive jump phases (each cycle preferably having a duration of less than 2 , 5 seconds, duration which corresponds preferably to the maximum duration to cover a complete rotation of 360 °), so that:

each jump phase comprises a phase of acceleration of the detector around the axis of rotation of the motor and then a phase of deceleration of the detector around the axis of rotation of the motor. Each jump phase may comprise an acceleration phase of the constant acceleration sensor around the axis of rotation of the motor and then a deceleration phase of the constant deceleration detector around the axis of rotation of the engine. The constant acceleration is preferably equal, in absolute value, to the constant deceleration.

The detector is preferably a thermal infrared detector which is uncooled.

The detector may be a bolometric detector, preferably microbolometric type.

The method according to the invention may comprise a construction, by means of construction, of at least one panoramic image, each panoramic image being constructed by assembling several individual images acquired by the detector during different imaging phases of a cycle. imaging phases and jump phases, each of these assembled individual images being derived from an imaging phase distinct from the imaging phases from which the other individual images assembled are derived. The construction of at least one panoramic image may include:

- A construction of a complete panoramic image imagining 360 ° around the axis of rotation of the engine by assembling several individual images acquired by the detector during different imaging phases of a cycle of imaging phases and phases jump, and / or

a construction, by the means of construction, of several sectorial panoramic images imagining distinct zones of the environment distributed at 360 ° around the axis of rotation of the engine, each sectorial panoramic image being constructed by assembling several individual images acquired by the detector during different imaging phases of a cycle of imaging phases and jump phases.

The control means can control a rotation of the detector around the axis of rotation of the motor in less than 2.5 seconds for the acquisition of all the individual images to build the complete panoramic image or sectorial panoramic images. The control means can control the rotation of the detector around the axis of rotation of the motor according to several cycles of imaging phases and jump phases (preferably so that during each cycle of jumping and imaging phases, the detector makes a maximum of two or a single turn (preferably less than one revolution) complete around the axis of rotation of the motor), and in a return phase between each pair of successive cycles, so that during each phase back the detector rotates about the axis of rotation of the motor in a direction of rotation opposite a direction of rotation to go during the jump phases.

The method according to the invention may comprise a use of an electrical wire connection between the detector and a part of the device according to the invention which remains stationary during the jumping phases, the wire link comprising a sheet of wires whose one end is secured. of the detector and the other is integral with the stationary part, this sheet of wire being located:

The distribution between the two arcs of circle can pass from a minimum of distribution on one of the arcs of circle to a maximum of distribution on this same arc of circle when the detector does less than two turns of 360 ° around the axis of rotation of the motor, preferably a 360 ° turn or even preferably less than a 360 ° turn around the axis of rotation of the motor from a reference angular position. The angular reference position of the detector around the axis of rotation of the motor is preferably the position at which the detector returns at the end of each return phase.

During each acceleration phase and each deceleration phase, the acceleration and deceleration are preferably greater, in absolute value, at 200 rad / s ² and / or less than 2000 rad / s ² .

DESCRIPTION OF THE FIGURES AND EMBODIMENTS Other advantages and particularities of the invention will appear on reading the detailed description of implementations and non-limiting embodiments, and the following appended drawings:

FIG. 1 is a schematic side view of a preferred embodiment of device 100 according to the invention,

FIG. 2 is a view from above of the individual image acquisition unit 1 of the device 100 according to the invention of FIG.

FIG. 3 illustrates the angular velocity of the detector 51 of the acquisition unit 1 of FIG. 2 as a function of time, during a so-called jump phase and then a so-called imaging phase,

FIG. 4 illustrates the angular position of the detector 51 of the acquisition unit 1 of FIG. 2 as a function of time, during a so-called jump phase and then a so-called imaging phase,

FIG. 5 illustrates the angular position of the detector 51 of the acquisition unit 1 of FIG. 2 as a function of time, during a so-called jump phase and then a so-called imaging phase, and then a new jump phase. 11 then a new imaging phase 12,

FIG. 6 illustrates the angular position of the detector 51 of the acquisition unit 1 of FIG. 2 as a function of time, during a cycle of imaging phases 12 and successive jump phases 11, this cycle comprising fifteen jump phases 11 and sixteen imaging phases 12, this cycle being followed by a return phase 13,

FIG. 7 is a perspective view of a ply 14 of wires between the detector 51 and an immobile part 24 of the device 100 according to the invention. of FIG. 1, for an angular position θ = 0 radian (or 0 °) of the detector 51 about the axis 16 with respect to a reference angular position 15,

FIGS. 8 and 9 are perspective views of the ply 14 of wires, for an angular position θ = π radian (or 180 °) of the detector 51 around the axis 16 with respect to the reference angular position (FIG. as for the schematic view of Figure 1), and

- Figure 10 is a perspective view of the ply 14 son, for an angular position θ = 2π radian (or 360 °) of the detector 51 about the axis 16 relative to the reference angular position 15.

These embodiments being in no way limiting, it will be possible to consider variants of the invention comprising only a selection of characteristics described or illustrated subsequently isolated from the other characteristics described or illustrated (even if this selection is isolated within of a sentence including these other features), if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art. This selection comprises at least one preferably functional characteristic without structural details, and / or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention from the state of the art. earlier.

Firstly, with reference to FIGS. 1 to 10, a first embodiment of imaging device 100 according to the invention embodying a method according to the invention will be described.

We will hear:

by "cycle" an assembly comprising several imaging phases 12 and several jump phases 11 (all the jump phases 11 of the same cycle 25 having the same direction of rotation of the detector 51 around the axis 16) . A cycle can allow the construction of a "complete panoramic image" or one or more "sectorial panoramic image (s)". - "Individual image" an image obtained by the detector 51 during an imaging phase 12 when the detector is fixed.

- By "panoramic image" an image obtained by construction from several individual images combined. A panoramic image can be:

a "complete panoramic image", which is an image imaging 360 ° around the device 100 (that is to say around the axis 16), or

o a "sectorial panoramic image", which is an image imitating only a limited sector of the environment

52 (less than 360 ° around the device 100 that is to say around the axis 16).

The device 100 comprises a detector 51, arranged to acquire an individual image (through a window 10) of an environment 52 (located around the detector 51) by converting a light flux (coming from the environment 52) into an electrical signal.

The detector 51 is part of an acquisition unit 1 (also called "camera" in the present description) typically also comprising optical components such as an objective.

The acquisition unit 1 typically comprises:

the objective, which creates the individual image of the environment 52 on the detector 51,

the detector 51, which converts the luminous flux into an electrical signal,

a reading electronics which amplifies and conditions the signal, preferably a preprocessing electronics which corrects the defects specific to the acquisition means and reconstructs a panoramic image.

The device 100 further comprises a processing panel (external to the cover 9 and not shown) which detects threats in the scene, tracks them and presents the results in a synthetic form.

The acquisition unit 1 is a passive system emitting no electromagnetic radiation unlike a radar or a lidar. The analyzed signal is for example: - in the visible spectrum for the human eye: a variation of the luminous flux from the sun or a lighting network and reflected by the environment 52, and / or

in the thermal infrared (IR) spectrum: a variation of emissivity or local temperature of the environment 52 specific to the behavior of a living being or of a vehicle.

The camera 1 perceives the scene or environment 52 through the peripheral window 10. The camera 1 creates a high resolution individual image of a restricted sector of the environment 52.

The detector 51 is in a plane 53, and is arranged to acquire an individual image of the environment 52 centered on an optical axis 54 (which is the optical axis of the camera 1) which is perpendicular to the plane 53.

The peripheral port 10 allows the device 100 to aim the surrounding panorama 52 while helping to close the internal volume of the device 100 to isolate external aggressions (rain, humidity, dust). Advantageously, for the use of a camera 1 not operating in the visible, the material of the window 10 may be selected opaque (in the range visible by the human eye) and / or colored to improve the discretion of the system (camouflage and masking of its moving parts). In the field of the infrared, the porthole 10 is for example Germanium.

The device 100 also comprises, in a main cover 9, a motor 4.

The main cover 9 keeps the elements it contains under a controlled atmosphere away from external aggression (rain, humidity, dust). It hides the moving parts.

The motor 4 comprises a single shaft 17 arranged to be movable in rotation. This shaft 17 is arranged to be rotatable about an axis of rotation 16 of the engine.

The axis 16 is in the plane 53.

The motor 4 is arranged to convert electrical energy into a rotational movement of the motor shaft 17. The motor 4 is arranged to drive the detector 51 in rotation (via the rotation shaft 17 of the motor 4 secured to a support 2 and the detector 51) around the axis of rotation 16 of the engine.

The detector 51 comprises a two-dimensional array of pixels. Each pixel has an angular resolution of the environment 52 (through the lens and all the other optical components of the acquisition unit 1), around the axis of rotation 16 of the motor, preferably less than 2, 5 milliradians, or even preferably less than 0.7 milliradians (mrad).

Detector 51 is a detector comprising bolometers (preferably microbolometers) for converting electromagnetic radiation or light flux (from environment 52) into an electrical signal.

The camera 1 comprises as detector 51 a module (thermal infrared microbolometer) of 640 x 480 elements (or pixels). The detector 51 is equipped with an open lens at f / 1.1 focal length 25mm (TAU 2.7640 provided by FLIR Systems).

The horizontal field of the camera 1 is of the order of 25 °. Its vertical field is of the order of 20 ° which allows after the geometric corrections to obtain the image of a panoramic banner of height 18 °.

Sixteen shots on successive angular sectors constitute a complete 360 ° panoramic image around the axis 16.

The complete panoramic image thus produced has a field of 360 ° xl8 °. Its format is 16 x 640 x 512 = 10240 x 512 pixels. Its spatial resolution is of the order of 0.6mrad (18 ° / 512).

The motor 4 is arranged to drive the detector 51 in rotation in the direct drive mode, that is to say without intermediate piece, between the motor 4 (or the rotary shaft 17 of this motor 4) and the detector 51, mobile in rotation about an axis parallel to the axis 16 of rotation of the motor 4 or according to any other degree of freedom in rotation or in translation. Indeed, the device 100 does not include, between the motor and the detector, an intermediate piece movable in rotation about an axis parallel to the axis of rotation of the motor or according to any other degree of freedom in rotation or in translation. It is said that the detector is embedded on the rotation shaft 17 of the engine 4. The device 100 comprises an electric wire link 3 between the detector 51 and a part of the device 100 arranged to remain stationary during the jump phases 11, the wire link 3 comprising a sheet 14 son.

The motor 4 allows the rotational drive of the mobile part consisting of the camera 1, its support 2 and the mobile part 14 of the link 3 around the axis 16 preferably oriented vertically to explore the surrounding panorama. 52.

The motor 4 is chosen according to the following characteristics to carry out the driving of the load:

- The torque of the engine 4 must be sufficient during the acceleration phases 11a or 13a and deceleration 11b or 13b.

- The maximum speed allowed by the engine 4 must be greater than the speed reached during the movement in the jump phase 11 or the return phase 13.

- The ratio between the moment of inertia of the load and that of the rotor of the motor must not be too high.

The size and mass of the engine 4 must be compatible with the compactness and transportability objectives of the device 100.

- Its cost must be reasonable.

The ratio of the moments of inertia is chosen not to exceed 20, recommended value on average by the motor manufacturers: considering the moment of inertia of the load, the moment of inertia of the rotor of the motor 4 chosen must thus be greater than 4.10 ^"6 kg m ² .

The motor 4 has a torque greater than 0.01 N.m and / or less than 0.5

N.m.

Given the different configurations of the camera 1, the control law and taking into account a safety factor of two, for the motor 4 to work in a comfort zone, the motor 4 chosen preferably has a torque greater than 0.1 Nm.

The maximum speed accessible to the engine 4 must be greater than 600RPM.

Drive Motor 4 is a compact, low-power "brushless" servomotor with high efficiency and high torque (TC 40 0.32 of the manufacturer's range M PC) equipped with a resolver of high resolution. The choice of the resolver is dictated by the need for a high angular resolution, compatible with the expected positioning accuracy.

The selected reference motor TC 40 0.32 has the following characteristics which are suitable:

- Moment of inertia of the rotor: 4.7. 10 ^"6 kg m ²

- Rated torque: 0.32Nm

- Maximum speed: 5000RPM

The support 2 makes it possible to fix the acquisition unit 1 on the shaft 17 of the rotary drive motor 4.

The support 2 is directly attached to the shaft 17 of the engine 4, without a transmission / reduction system, which provides a compact assembly and ensure a game-free, accurate, reliable and quiet movement.

The motor 4 is a brushless motor (or "Brushless" in English).

A brushless motor, or permanent magnet synchronous synchronous machine, is an electrical machine of the synchronous machines category, the rotor of which consists of one or more permanent magnets and provided with a rotor position sensor (effect sensor Hall, synchro-resolver, or incremental encoder for example). Its name comes from the fact that this type of engine contains no rotating collector and therefore no brushes.

The "brushless" motor technology is particularly suitable for the application:

- it has high reliability, equivalent to that of engines

AC and 4 times higher than that of a DC motor with brushes. Wear is limited to that of ball bearings.

- It allows greater power for the same mass and the same size. "Brushless" motors are more compact than AC and DC motors. They are 2 to 3 times lighter than DC motors.

- their efficiency is better than that of DC motors. Their control by electronics 6 allows the optimal management of the yield.

- the vibrations and noise generated by "brushless" motors are less. - this technology allows easy control of the movement using an electronic 6.

The device 100 further comprises, in the main cover 9, control means 6, 8 (more specifically an electronic control 6 of rotation), arranged to control (via an angular encoder 5 rotation) the rotation of the detector 51 around the axis of rotation 16 of the motor 4 according to at least one cycle of several imaging phases 12 and of several alternating jump phases 11 (in the same cycle 25, there are no two successive jump phases 11 without intermediate imaging phase 12 and there are no two successive imaging phases 12 without intermediate jump phase 11) and successive, the angular position of the detector 51 around the axis of rotation 16 of the motor 4 being different for each imaging phase 12 of the same cycle.

Each cycle of imaging phases 12 and jump phases 11 preferably comprises at least three (more preferably at least ten) imaging phases 12 and at least three (more preferably at least ten) imaging phases. jump 11.

Each cycle 25 of imaging phases 12 and jump phases 11 preferably has a duration of less than 2.5 seconds, which corresponds to the maximum duration to cover a complete rotation of 360 °.

The control electronics 6 of the engine 4 consists of a HORN module and ELMO with resolver input (10 to 15 bits).

As noted above, the 360 ° x18 ° field of view is covered by 10240 x 512 pixels. The stability of the shaft 17 during the imaging phases 12 must be of the pixel order to maintain optimum image quality. This implies a resolution better than 10000 points per revolution for the encoder 5 and low inertia so as not to increase the driving torque required. Resolver-type coding technology achieves this resolution. The encoder 5 is of the resolver type. Typically, the encoder 5 is a TAMAGAWA reference coder

TS2610N 171 E64.

The angular encoder 5 locates the position of the shaft 17 of the engine 4. Its accuracy must be compatible with the resolution of the image, to enslave the position of the shaft 17 of the motor 4 with a precision compatible with the size of a pixel.

The control means 6, 8 (more specifically an electronic control and communication 8) are arranged to control an acquisition of an individual image of the environment 52 by the detector 51 during each imaging phase 12.

During each imaging phase 12, the detector 51 is fixed (with respect to the engine 4) and does not rotate around the axis of rotation 16 of the engine 4, and acquires an image of the environment 52 .

Each jump phase 11 comprises only an acceleration phase 11a (with constant acceleration) of the detector 51 around the axis of rotation 16 of the motor 4 and then a deceleration phase 11b (at constant deceleration) of the detector 51 around the axis of rotation 16 of the motor 4, always with a speed in the same direction of rotation about the axis of rotation 16 of the motor 4.

The control and communication electronics 8 make it possible to:

transmitting the scanning law of the environment 52: direction, amplitude, speed, acceleration. Advantageously, the direction can be fixed in any bearing angle corresponding to the direction of a potential threat, allowing the transmission at a higher rate of the image in this direction (staring mode) and thus improve the identification of the threat or, conversely, its acquittal. An automatic tracking function is possible after snapping on the threat;

remote control of the camera 1: need to perform image uniformity corrections for a microbolometer camera 1 or to control the gain and the integration time for another type of camera 1, and more generally to access to all camera configuration settings 1.

transmitting the video signal from the camera 1: advantageously, the video data is corrected geometrically to facilitate the development of the panoramic image by simple juxtaposition (or "Stitching") thus corrected images. They are enriched with data specific to the environment 52 (temperature, geolocation) and to the operation of the system (data from the ILO).

The device 100 comprises means for constructing at least one panoramic image by assembling several individual images acquired by the detector 51 during different imaging phases 12 of a cycle 25 of imaging phases 12 and of jump phases 11, each these assembled individual images being derived from an imaging phase 12 distinct from the imaging phases 12 from which are derived the other individual images assembled. These means are located inside or outside the cover 9 (or are distributed between the two). These construction means comprise a computer, a central or calculation unit, an analog electronic circuit (preferably dedicated), a digital electronic circuit (preferably dedicated), and / or a microprocessor (preferably dedicated), and / or software means.

Each jump phase 11 comprises only an acceleration phase 11a of the detector 51 with constant acceleration around the axis of rotation 16 of the motor 4 and then a deceleration phase 11b of the detector 51 with constant deceleration around the axis of rotation 16 4. The constant acceleration is equal, in absolute value, to the constant deceleration.

The detector 51 is a thermal infrared detector (typical wavelengths detected: 7.5 pm to 13.5 pm) uncooled, of the bolometric or microbolometric type.

The detector 51 is said to be "uncooled" because the device 100 does not include any cooling system (electrically powered (refrigerator-type system, Peltier module, Stirling device, etc.) and / or using a liquid (heat pump, etc. ..) and / or a gas (Joule-Thompson device, fan, etc.)) arranged to specifically cool the detector 51, other than the simple ambient air (static) surrounding the detector 51 or the unit 1.

The means for constructing at least one panoramic image are arranged: to build a complete panoramic image imaging 360 ° around the device 100 or the axis 16 of rotation of the engine 4, by assembling several individual images acquired by the detector 51 during different imaging phases 12 of a cycle 25 of imaging phases 12 and jump phases 11, and / or

to construct a plurality of sectorial panoramic images imaging distinct zones of the environment 52 distributed at 360 ° around the device 100 or the axis 16 of rotation of the engine 4, by assembling several individual images acquired by the detector 51 during different imaging phases 12 of a cycle 25 of imaging phases 12 and jump phases 11.

The control means 6, 8 are arranged to control a rotation of the detector 51 about the axis of rotation 16 of the motor 4:

in less than 2.5 seconds for the acquisition of all the individual images acquired by the detector 51 during different imaging phases 12 of a cycle 25 of imaging phases 12 and of jump phases 11, and necessary to a construction of a complete panoramic image imaging 360 ° around the device 100 or the axis 16 of rotation of the engine 4, and / or

in a time less than that necessary for producing the complete panoramic image for the acquisition of all the individual images acquired by the detector 51 during different imaging phases 12 of a cycle 25 of imaging phases 12 and jump phases 11, and necessary for a construction of sectorial panoramic images.

The control means 6, 8 are arranged to control the rotation of the detector 51 around the axis 16 of rotation of the motor 4 according to several cycles of imaging phases 12 and jump phases 11, and in a return phase 13 between each pair of successive cycles, so that during each return phase 13 the detector 51 rotates about the axis of rotation 16 of the motor 4 in a direction of return rotation 18 opposite a direction of rotation going 19 traveled during the jumping phases 11.

The electrical connection 3 allows the transmission, between the fixed part (5, 6, 7, 8, 9, 10) and the mobile part (1, 2, 14), of the video signal of the camera 1, of the power supply of camera 1 and communication bidirectional between the camera 1 and the electronics 8 control and communication.

With reference to FIGS. 7 to 10, the electric wire link 3 comprises the sheet of wires 14 (or "flex"), one end 21 of which is secured to the detector 51 and the other end 22 is integral with a portion 24 of the device 100. arranged to remain stationary during the jumping 11 and return 13 phases (and thus secured to the main cover 9, via nuts 24, and therefore control means 6, 8) while the detector 51 moves by its rotational movement, this sheet of wire 14 being located:

distributed in a distributed manner between two arcs of circles 14a, 14c (preferably of the same radius), each circular arc 14a, 14c being located in a disk-shaped surface perpendicular to the axis of rotation 16 of the motor 4, so that by traversing a path along the web 14 starting from the immobile part 24 towards the detector 51:

o is rotated about the axis of rotation of the motor in a first direction of rotation when traversing this path on one of the arcs of circle 14a, and

o is rotated about the axis of rotation of the motor in a second direction of rotation opposite the first direction of rotation when traversing this path on the other arc 14c,

- On a loop 14b connecting the two circular arcs 14a, 14c, said loop preferably having a radius of curvature centered on an axis 20 perpendicular to the axis of rotation 16 of the motor 4.

The sheet of threads 14 is arranged so that the distribution between the two circular arcs 14a, 14c goes from a minimum of distribution on one of the arcs of a circle to a maximum of distribution on this same arc when the detector 51 does exactly a 360 ° rotation or less of a 360 ° turn around the axis of rotation 16 of the engine 4 from a reference angular position 15 (shown in FIG. 7) of the detector 51 about the axis rotation of the motor 4. In FIG. 7, the distribution is maximum for the arc 14c and minimum for the arc 14a. In Figure 10, the distribution is maximum for the arc 14a and minimum for the arc 14c. In this case, the rotation must have a reversal point (no continuous rotation on an indefinite number of revolutions).

It should be noted that between FIGS. 7 and 10 the detector 51 rotates 360 ° about the axis 16 while the loop 14b is only one half turn. Thus, along the length of the arc 14c at the starting position of FIG. 7, it is possible, in a variant, to make the distribution between the two circular arcs 14a, 14c pass from a minimum of distribution on one of the arcs of a circle to a maximum of distribution on the same arc when the detector 51 makes exactly two turns of 360 ° (or less than two revolutions) around the axis of rotation 16 of the engine 4 from the reference angular position 15 (equivalent to that of FIG. 7) of the detector 51 around the axis of rotation 16 of the engine 4, whereas the loop 14b only has a single turn of 360 ° (or minus) about the axis of rotation 16 of the motor 4 from the reference angular position 15.

Thus, for each cycle 25 of imaging phases 12 and jump phases 11, the detector 51 makes at least two complete turns (preferably at most one complete revolution) of rotation about the axis 16 (of preferably less than one full revolution of rotation about axis 16).

The reference angular position 15 of a detector 51 around the axis of rotation 16 of the motor 4 is the position at which the detector 51 returns at the end of each rewinding phase 13.

The advantage of such a sheet of son 14 is to be little subject to wear, unlike a rotary collector by friction of electrical contacts. The web 14 also provides an advantage of compactness, and low cost, compared to a solution by rotating collector hollow axis (expensive, bulky and fairly massive). Finally, another advantage of the ply 14 is that its replacement does not involve disassembly of the detector 51 with respect to the motor 4. It is sufficient to disconnect and reconnect at both ends of the ply 14. There are no registers lage to provide in case of replacement. The exchange can be done in the field.

The entire device 100 has a mass of less than 2 kilograms. The entire moving part (the acquisition unit 1 and its support 2 and the flex 14) driven in rotation by the motor 4 about the axis of rotation 16 the motor 4, integral with the shaft 17 of rotation of the motor 4, and comprising the detector 51, has a mass less than 300 or 200 grams.

During each acceleration phase 11a (at constant acceleration) and each deceleration phase 11b (at constant deceleration), the acceleration 11a and the deceleration 11b are greater, in absolute value, than 200 rad / s ² and / or less than 2000 rad / s ² .

The optical axis 54 is indexable manually in site, via the nuts 23, in the 0 ° and +/- 6 ° positions relative to the horizontal, which makes it possible to adapt the angle of view in site to the situation encountered at the installation (aim horizon, aim sky or aim ground). If these positions are not suitable, continuous indexing is possible (up to + -18 °). The interest of the indexed positions is that they make it possible to define the orientation of the camera 1 with sufficient precision to apply acceptable geometric corrections without additional calibration. However, it should be noted that the device 100 does not comprise an intermediate piece movable between the motor 4 and the detector 51 in rotation to adjust this optical axis 54. Indeed, this optical axis adjustment 54 is not possible on the device 100 but is only possible on a set of disassembled elements from the device 100 (without window 10, the nuts 23 loose therefore without motor 4 nor control means 6, 8 functional, etc.).

The device 100 further comprises a fixed base 7 which makes it possible to support and interface the device 100 with mechanical and / or electrical means (power supply, video signal). Advantageously, this base 7 is connected to a system allowing the geolocation of the device 100, and / or to a clinometer, and / or to a sensor indicating the direction of the magnetic north or the geographic north.

The imaging method implemented in the device 100 comprises:

a drive in rotation, by the motor 4, of the detector 51 around the axis of rotation 16 of the motor 4, the detector 51 being rotated in the direct drive mode (ie without an intermediate piece, between the motor 4 and the detector 51, mobile in rotation about an axis parallel to the axis of rotation 16 of the motor 4 or any other degree of freedom in rotation or in translation), the detector 51 being arranged to acquire an individual image of the environment 52 by converting a light flux from the environment 52 in an electrical signal,

a command, by the control means 6, 8, of the rotation of the detector 51 around the axis 16 of rotation of the motor 4 according to at least one cycle 25 of imaging phases 12 and successive jump phases 11, so that:

during each imaging phase 12, the detector 51 is fixed and does not rotate about the axis of rotation 16 of the engine 4, and acquires an image of the environment 52, and

o each jump phase 11 comprises (preferably only) an acceleration phase l ia of the detector 51 around the axis of rotation 16 of the motor 4 and a deceleration phase 11 b of the detector 51 around the axis of rotation 16 of the engine 4,

a construction, by the means of construction, of at least one panoramic image by assembling several individual images acquired by the detector 51 during different imaging phases 12 of a cycle 25 of imaging phases 12 and phases of jump 11, each of these individual images assembled resulting from an imaging phase 12 distinct from the imaging phases 12 from which are derived the other individual images assembled.

The control means 6, 8 control the rotation of the detector 51 about the axis of rotation 16 of the motor 4 according to several cycles of imaging phases 12 and jump phases 11 (so that during each cycle 25 phases of jump 11 and imaging 12, the detector 51 does at most a single complete revolution around the axis 16 of the motor 4), and in a return phase 13 between each pair of successive cycles 25, so that during each phase return 13 the detector 51 rotates about the axis of rotation 16 of the motor 4 in a reverse direction of rotation 18 opposite a direction of rotation go 19 traveled during the jump phases 11.

The drive motor 4 is driven by the electronics 6 for controlling the rotation according to a scanning law using the angular position signal supplied by the encoder 5, which allows a closed-loop servocontrol. The rotational movement must be stopped (imaging phase 12) for a compatible time of the minimum image acquisition time and must be as fast as possible (jump phase 11) between two image acquisition sectors . This type of movement makes it possible to take a large number of shots (high spatial resolution) in a short time (high speed) over an extended angular sector (panoramic image).

The law of the angular position e (t) of the detector 51 around the axis 16 of the motor 4 as a function of time is calculated so that the optical axis 54 is fixed in the frame of the environment 52 during the phases 12 said imagery corresponding to the aim towards the successive sectors in the field. Between the imaging phases 12, the optical axis 54 moves rapidly to align with the axis of the following sector, these are the so-called jump phases 11. Once a rotation has been performed, 360 ° or on one or more angular sector (s) more reduced (s)), there may be a so-called return phase 13 which returns to the bearing axis of the first sector without performing a complete turn .

The necessary torque C (t) (as a function of time t) is set by the value of angular acceleration and by the inertia J of the load 1, 2, 14 to move through the formula:

C (t) = J ^ Q (t)

dt

The maximum torque is reached during the acceleration phases 11a, 13a and deceleration 11b, 13b during the jump 11 and return 13 phases.

During each imaging phase 12, Q (t) = constant: the fixed individual image is printed on the detector 51 and the reading is made before the next imaging phase 12. Thus, during the imaging phases 12, the shaft 17 of the motor 4 must be fixed. The reading of the individual image of the environment 52 by the detector 51 occurs at the end of each imaging phase 12. In fact, the microbolometers are micro-resistors whose value varies as a function of their temperature. This depends on the radiation received, directly related to the temperature of the point of the scene conjugated with the pixel in question. If a micro resistance is conjugated with a hot stage portion, it receives IR radiation from it and heats up; conversely, if this same micro-resistance is conjugated with a portion of cold scene, it emits IR radiation absorbed by it and cools. An electronic system measures the value of these resistors at each individual image acquisition. However, a microbolometer detector has a very long thermal time constant, mainly because of their thermal inertia; the order of magnitude of the time constant is thus a few ms for the best detectors. In order for the current single image to be only slightly influenced by the previous one or images, it is then necessary for a duration of typically a few tens of milliseconds to elapse between the stabilization of the line of sight 54 in the scene 52 ( ie the beginning of an imaging phase 12) and the beginning of the reading of the individual image by the detector 51 (for this same imaging phase 12).

During each jump 11 and return phase 13, 0 (t) must be a zero derivative (rotational speed) continuous function at the beginning and end of the movement so that the movement is carried out without excessive acceleration, without excessive consumption of energy. energy and without excessive vibrations. The law that minimizes the torque and the consumption of the motor 4 is to increase the angular velocity co (t) with constant acceleration and then to decrease it with constant deceleration until the following position is reached: with reference to FIG. 3, the speed thus varies in a triangular form.

Thus, each jump phase 11 comprises an acceleration phase 11a of the detector 51 with constant acceleration around the axis of rotation 16 of the motor 4 and a deceleration phase 11b of the detector 51 with constant deceleration around the axis of rotation. 16 of the engine 4. Each return phase 13 comprises an acceleration phase 13a of the detector 51 with constant acceleration around the axis of rotation 16 of the motor 4 and then a deceleration phase 13b of the detector 51 with constant deceleration around the axis of rotation 16 of the motor 4.

The acceleration and deceleration values may be different, but to limit the torque and the power consumption, it is preferable that they be equal. Thus, for each jump phase 11 (as for each return phase 13), the constant acceleration is equal, in absolute value, to the constant deceleration.

The value of the acceleration (equal to that of the deceleration) then depends only on the time allowed for the jump 11 and the amplitude of the jump 11.

For a triangle-shaped speed law, the acceleration, constant,

40

is given by the following law: a = - Θ being the amplitude of the jump 11 or the return 13 in radians

T being the time taken to perform jump 11 or return 13 in seconds

4Θ

The couple is: C = J-

J being the inertia of the load driven by the motor 4 (in kg m ² ) By minimizing the inertia of the load, it is possible to realize large rotational movements in short times, with a low maximum power.

The construction of at least one panoramic image comprises, according to the variant:

- a construction of a complete panoramic image

360 ° around the axis of rotation 16 of the engine 4 by assembling several individual images acquired by the detector 51 during different imaging phases 12 of a cycle 25 of imaging phases 12 and jump phases 11, or

a construction, by the means of construction, of several sectorial panoramic images imaging distinct zones of the environment 52 distributed at 360 ° around the axis of rotation 16 of the motor 4, each sectoral panoramic image being constructed by assembling several individual images acquired by the detector 51 during different imaging phases 12 of a cycle 25 of imaging phases 12 and jump phases 11.

The refresh rate of the panoramic images is

0.44Hz (a new full 360 ° panoramic image every 2.3 seconds). Thus, the control means 6, 8 control a rotation of the detector 51 around the axis of rotation 16 of the motor 4 in less than 2.5 seconds for the acquisition of all the individual images (of a single cycle 25 of imaging phases 12 and jump 11) to build the complete panoramic image or sectorial panoramic images.

This rate is limited by the image frequency of the selected camera 1, clamped at 7.5 Hz for exportability reasons (US ITAR export control rules being applied if f> 9Hz). In absolute terms, a camera 1 that would work at 30Hz would theoretically achieve a frame rate of around 1.75Hz.

The image frequency of 7.5 Hz corresponds to an image period of 1000 / 7.5 = 133 ms per angular sector, to be distributed between the imaging phase 12 and the jump phase 11. The time required for the imaging phase 12 is at least equal to the thermal response time of the detector 51 with microbolometers, plus the reading time of an image, ie a total of 70ms minimum.

Dynamic motion control was first performed to test the system's response limits:

- A jump phase 11 can be performed in about 40ms,

An imaging phase 12 can therefore last up to about 90 ms (133-40), ie more than the 70 ms necessary for the formation and reading of the individual image for the microbolometer detector 51. about 120ms for an almost complete tour.

For this setting, the average consumption of the system is still very low, of the order of 5W. It would allow in absolute, if the frame rate of the camera 1 was not limited to 7.5 Hz, to make a panoramic image in 1.6s or 0.62Hz for a complete panorama. In practice, to further limit consumption and reduce the inertia required for the fixed part, the chronology of the phases is chained in the following manner, in the case of imaging a 360 ° complete panorama:

- Duration of each jump phase 11: Ts = 57ms

Duration of each imaging phase 12: Ti = 76 ms (= 133-57)

- Duration of the return phase 13: Tr = 190ms

The duration of 190ms corresponds to the loss of an individual image during the return phase 13 (190 = 57 + 76 + 57).

Under these conditions, the average consumption of the system is about 4W. The analysis time of a complete 360 ° panorama is 17 x 133 = 2261ms, which corresponds to an image rate of 0.44Hz for a complete panorama.

This consumption is largely compatible with the power supply possibilities of integrated and embedded equipment.

For a complete panoramic image, the positions of the camera 1 for the different imaging phases 12 are equidistributed in one turn (for example 16 positions spaced 22.5 °).

The sweeping law is defined at least by the following parameters which make it possible to drive the motor 4 by a velocity triangle law:

- Angular origin of the sweep figure

- Angular positions of the stages: 16 positions spaced by 22.5 ° - Maximum acceleration and deceleration for the jump phases 11:

480 rad / s ²

- Maximum acceleration and deceleration for the return phases 13: 650 rad / s ²

- Maximum speed for each jump phase 11:14 rad / s

- Maximum speed for each return phase 13: 62 rad / s

The following parameters are optimized to obtain a satisfactory stability during the imaging phases 12 (stability less than the pixel) and a displacement according to the triangle law during the phases of movement (jump 11 or return 13): - speed regulation parameters: P the proportional parameter and I the integral parameter

- Regulation parameters in position: P the proportional parameter The ELMO HORNET reference electronic module 6 was selected because of its ability to ensure:

The positioning repeatability better than an image pixel from the information delivered by the encoder 5,

- Slaving in speed and position during the imaging phase 12, jump 11 and return 13.

In this method implemented by the device 100, the electric wire link 3 and the wire ply 14 previously described are used.

Note that the device 100 allows to switch from full panning mode (360 °) to a reduced field mode but high frame rate. Indeed, it is possible to orient the acquisition unit 1 in the desired direction in the bearing, and to maintain constant the setpoint of the angle of rotation. The frame rate can then be increased to the maximum rate of the device 100, 7.5 to 30 Hz or more depending on the camera model 1 chosen.

In this mode, it may be advantageous to take advantage of the high frame rate to snap the tracking on a target of interest in the center of the field with a conventional image correlation algorithm.

The design also makes it possible to operate in intermediate modes, with reduced scanning to a few sectors not representing 360 ° but making it possible to monitor one (or more) useful zone (s) only.

Finally it is possible simply to electronically adjust the origin of the scan to further optimize the use and coverage.

Note also that the device 100 is fully compatible with the use of a camera 1 in the visible or near IR by adapting the window 10. In this case, the time required for the acquisition of a single image no longer has the same constraints as for a detector 51 with microbolometers since it can then be reduced to a few milliseconds. It is thus possible to mount at rates above 1Hz for a complete panoramic image.

Such implementation flexibility for use in a large number of operational scenarios is not possible in the state of the art as described by WO 2013/109976 in which:

the successive positions being defined by the geometry of a cam, it is not possible to orient the line of sight at will on an intermediate position,

the movement of the driving system being continuous, it is not possible to limit the acquisition to one or more sectors corresponding to a smaller number of images on one or more fractions of a turn only and thus to benefit from a higher refresh rate of the image of said sector. Among the other advantages conferred by the device 100 according to the invention compared to the state of the art, it will be noted:

the use of a non-cooled thermal infrared detector 51, preferably of the microbolometer type, for a set of reasons:

o the cost of this technology is compatible with wide distribution in particular civil markets;

a camera 1 of reduced size and mass, especially because of the lack of cooling system, not necessary for this technology; hence a positive impact on mass, volume, consumption, reliability and acoustic discretion.

o the resolution of camera 1 compatible with detection ranges of the order of km on small objects (standing pedestrian);

- With a reduced number of moving parts (shaft 17 and integral parts 1, 2, 14), simplifies the design, assembly, maintenance, reduces the cost, increases reliability (no moving parts intermediate, so less friction or wear), we optimize the angular precision (no games), we eliminate sources of noise and vibration, we reduce consumption (no friction).

- Stop imaging phase 12 is done without resorting to a lock or any form of mechanical indexing. This further reduces the number physical elements (see the advantages mentioned above), and to have total flexibility on the sweep figure. The origin of the scan, its amplitude and its stop, will be configurable in the field, allowing an operator to reconfigure the system to adapt to changing operating conditions. It will be possible to re-set them to the video rate, which will for example to enslave the line of sight 54 on the direction of a threat in "pursuit" mode.

In summary, the technical solution proposed according to the invention, based in particular on the rotational drive of a camera 1 with a narrow live field of view by a motor 4, makes it possible, by a judicious choice of the various constituent elements, to realize a high-resolution, high-speed panoramic image in a compact, reliable and quiet package.

This solution is particularly advantageous in the case where the mobile part 1, 2, 14 has a low inertia. The torque required for movement is then lower. The inertia of the fixed part, which guarantees the stability, can thus be reduced, in favor of the reduction of weight and the improvement of the compactness. This is the case for example infrared cameras with current microbolometers. It is possible to print this type of camera 1 a jerky movement at a frequency of the order of 10 to 20 Hz (high rate, high resolution) to cover a wide sector without generating consumption or excessive vibration.

Of course, the invention is not limited to the examples that have just been described and many adjustments can be made to these examples without departing from the scope of the invention.

For example, depending on the variant or embodiment considered:

two successive cycles (whose jump phases of the detector 51 are all in the same direction of rotation going around the axis 16) are spaced apart by a return phase 13 (with a reverse direction of rotation 18 opposite to the one-way direction). 19), as previously described, or

o two successive cycles 25 have opposite directions of rotation of the detector 51 around the axis of rotation 16 16; the return phases 13 (without acquisition of individual images) are then useless and absent.

Of course, the various features, shapes, variants and embodiments of the invention may be associated with each other in various combinations to the extent that they are not incompatible or exclusive of each other. In particular all the variants and embodiments described above are combinable with each other.

Claims

Imaging device (100), comprising:

a detector (51), arranged to acquire an individual image of an environment (52) by converting a light flux coming from the environment into an electrical signal,

a motor (4), arranged to drive the detector in rotation about an axis of rotation (16) of the motor, the motor being arranged to drive the detector in rotation in direct drive mode, the device according to the invention not including, between the motor and the detector, an intermediate piece movable in rotation about an axis parallel to the axis of rotation of the motor,

control means (6, 8) arranged to control the rotation of the detector around the axis of rotation of the motor according to at least one cycle (25) of imaging phases (12) and jump phases (11) successive, so that:

o each jump phase comprises an acceleration phase (l ia) of the detector around the axis of rotation of the motor and a deceleration phase (11b) of the detector around the axis of rotation of the motor.

Device according to claim 1, characterized in that the motor is arranged to drive the detector in rotation in the direct drive mode, the device according to the invention does not comprise, between the motor and the detector, a rotatable intermediate part. around an axis parallel to the axis of rotation of the motor or any other degree of freedom in rotation or in translation. Device according to claim 1 or 2, characterized in that each jump phase comprises an acceleration phase of the constant acceleration sensor around the axis of rotation of the motor and a deceleration phase of the constant deceleration detector around the axis of rotation of the motor.

4. Device according to claim 3, characterized in that the constant acceleration is equal, in absolute value, to the constant deceleration.

5. Device according to any one of the preceding claims, characterized in that the detector is an uncooled thermal infrared detector, preferably microbolometric type. 6. Device according to any one of the preceding claims, characterized in that the detector comprises a matrix of pixels, each pixel having an angular resolution around the axis of rotation of the motor, less than 2.5 mrad. 7. Device according to any one of the preceding claims, characterized in that the motor is a brushless motor.

8. Device according to any one of the preceding claims, characterized in that it further comprises means for constructing at least one panoramic image by assembling several individual images acquired by the detector during different imaging phases of a cycle. imaging phases and jump phases, each of these assembled individual images being derived from an imaging phase distinct from the imaging phases from which the other individual images assembled are derived.

9. Device according to claim 8, characterized in that the means for constructing at least one panoramic image are arranged to construct a complete panoramic image imaging 360 ° around the device by assembling several acquired individual images by the detector during different imaging phases of a cycle of imaging phases and jump phases.

10. Device according to claim 8 or 9, characterized in that the means for constructing at least one panoramic image are arranged to construct several sectorial panoramic images imaging distinct areas of the environment distributed at 360 ° around the device, each sectoral image. being constructed by assembling several individual images acquired by the detector during different imaging phases of a cycle of imaging phases and jump phases.

11. Device according to claim 9 or 10, characterized in that the control means are arranged to control a rotation of the detector around the axis of rotation of the motor in less than 2.5 seconds for the acquisition of all the images. to build the complete panoramic image or sectorial panoramic images. 12. Device according to any one of the preceding claims, characterized in that the control means are arranged to control the rotation of the detector around the axis of rotation of the engine according to several cycles of imaging phases and jumping phases. , and in a return phase (13) between each pair of successive cycles, so that during each return phase the sensor rotates about the axis of rotation of the motor in a direction of rotation opposite a direction of rotation to go traveled during the jump phases. 13. Device according to any one of the preceding claims, characterized in that it comprises a wired electrical connection between the detector and a part of the device according to the invention arranged to remain stationary during the jump phases, the wired connection comprising a web of wires whose one end is secured to the detector and the other is secured to the immobile part, this sheet of wire being located:

o is rotated about the axis of rotation of the motor in a first direction of rotation when traversing this path on one of the arcs of circle (14a), and

o is rotated about the axis of rotation of the motor in a second direction of rotation opposite the first direction when traversing this path on the other arc (14c),

14. Device according to claim 13, characterized in that the sheet of son is arranged so that the distribution between the two circular arcs passes from a minimum of distribution on one of the arcs of a circle to a maximum of distribution on the same arc when the detector makes less than two 360 ° turns around the axis of rotation of the motor from a reference angular position (15).

15. Device according to any one of the preceding claims, characterized in that it has a mass of less than 2 kilograms.

16. Device according to any one of the preceding claims, characterized in that during each acceleration phase and each deceleration phase, the acceleration and deceleration are greater, in absolute value, than 200 rad / s ² and / or less than 2000 rad / s ² .

17. Device according to any one of the preceding claims, characterized in that the motor has a torque greater than 0.01 Nm and / or less than 0.5 N .m. 18. Device according to any one of the preceding claims, characterized in that the entire movable part rotated by the motor (4) about the axis of rotation (16) of the motor (4) has a mass less than 300 grams.

19. Imaging method, comprising:

a rotation drive, by a motor (4), of a detector around a rotation axis (16) of the motor, the detector being rotated in the direct drive mode, so that it does not there is no intermediate piece between the motor and the detector movable in rotation about an axis parallel to the axis of rotation of the motor, the detector being arranged to acquire an individual image of an environment (52) by converting a luminous flux from the environment into an electrical signal,

a command, by control means (6, 8), of the rotation of the detector around the axis of rotation of the motor according to at least one cycle (25) of imaging phases (12) and of jumping phases ( 11), so that: