DE102005020594A1 - Unmanned observation helicopter has two remote control cameras for stereo effect - Google Patents

Abstract

An unmanned, remote control helicopter is fitted with at least two cameras (5, 7) nominally set with parallel optic axes and with the ability to vary the angle between the optic axes up to 20 deg. The cameras are spaced apart by 5 to 50 cm. and are each fitted with a transmitter and separate remote control, and can be operated in a synchronous manner.

Description

background the invention

helicopter are rotorcraft aircraft with at least a motor-driven rotor. There are numerous embodiments with different numbers of rotors in different arrangements.

little one and light helicopters win in airborne observation (Observation from the air, extraction of optical information from an aircraft from) increasingly important. It dominates the classic embodiment with a main rotor, primarily for lift generation, and a Tail rotor for the torque compensation.

disadvantage this concept: about 20% of the drive power will be for the tail rotor needed and do not stand for the buoyancy available (reduced energy efficiency). Furthermore, the mechanics of the control is relative costly and complicated (collective & cyclic pitch, stabilization systems Etc.). Furthermore feature Helicopters of this type over a rather low flight stability.

at the propulsion technology of helicopters for airborne observation You can find the most common internal combustion engines. The electric drive is on the rise, however. Some advantages: quiet, reliable, weather-independent operating behavior, fine controllability, low vibration. The trend towards electric drive is forced by the continuous development of electrical energy storage, towards ever higher Energy and power density.

nevertheless is far from reaching the level of fossil fuels here, therefore the energetic efficiency in the development of electric helicopters always a big one Role plays to sufficiently long flight times and sufficient payloads to achieve. Above all, consistent lightweight construction is important.

to Obtaining the image information will be in the airborne observation Cameras of different types used. High picture quality was so far associated with relatively high weight, which prohibited the use in particularly compact helicopters. With the progressive miniaturization of camera technology can also this field of application will be tapped.

The Practicality of helicopters for airborne observation depends essentially on the type of flight guidance from. Two approaches So far, the focus has been on:

a) Manual control on sight (like model helicopter)

One Pilot standing on the ground sees and assesses attitude and movement of the helicopter and controls the device manually with a remote control transmitter.

Advantages:

• • Relative low technical effort
• • Great variability in the Flight movements - fast changes possible. Also sudden Obstacles can be avoided. Target tracking possible.
• • Fast Commissioning (no flight planning at a ground station)

Disadvantage:

• • Difficult service It requires special flying skills, which severely restricts the users of this type of control. difficulties Above all, the detection of the attitude as well as the sense-corrective activity the control functions in different flight situations. flies the helicopter z. B. on the pilot, are "reversed right and left": Controls the pilot to the right, the helicopter flies as seen from the pilot Left.
• • Range of application is limited The range is limited by the visibility, in which the attitude can still be reliably detected. It is depending on the size and geometry of the helicopter only about 50 to several hundred meters, at üb Overall dimensions of about 0.5 to about 3 m. An interruption of the line of sight usually leads to a crash after a short time, because necessary tax corrections do not occur. For the airborne observation in urban terrain (between buildings, vegetation) therefore only conditionally suitable (line of sight interrupted more often).

b) Automatic flight guidance

Of the Flight is at a ground station, z. A special computer, planned. For this purpose, path coordinates are typically specified, the the aircraft subsequently without manual control interventions automatically.

Advantages:

• • None flying skills required
• • Works also without line of sight

Disadvantage:

• • loss of time until use by previous flight planning
• • higher technical effort, expensive
• • (Yet) rather larger helicopters reserved (elaborate, heavier technology needed higher Payload)
• • low variability in the flight movements - no fast changes possible. A new route requires new time-consuming inputs. obstacles Dodge hardly possible. Too inflexible for target tracking. For the airborne Observation in urban terrain - between Obstacles - therefore poorly suited.
• • Mobility of the operator limited by bulky ground station.

own Research has shown that it is quite difficult to use a helicopter remote control to camera image, the aircraft safely to navigate in the room. A central problem is the estimation of Distances. Whether an obstacle is further away or so close that an evasive maneuver is needed, can be difficult to assess. Particularly sensitive are the persecution of moving targets and use in confined spaces (eg between or inside buildings).

Of the Invention is based on the object, an improved remote-controlled Helicopters for airborne Observation, in particular the observation task better solved can be, even in confined spaces and for the pursuit moving goals. The invention is further based on the object to provide an improved method of airborne observation.

Short outline the invention

According to the invention Task solved with an unmanned, remote-controlled helicopter for observation from the air, with at least two cameras on the helicopter a distance of 5 cm to 50 cm (measured from the lens center to Lens center) are provided, the optical axes approximately oriented in the same direction, with an angular deviation from one camera to another of a maximum of 20 degrees. Using this Technology can be a three-dimensional image impression in the viewer The camera images are generated with the distances much better estimated can be.

For transmission The camera images to the viewer, there are various options. According to a first embodiment the invention can for two cameras each one transmitter for wireless transmission of the camera images be provided. With that you can the picture information for get each camera separately to the ground, received there separately and provided to a viewer as a three-dimensional image.

Of the Distance from two cameras may preferably be between about 7 cm and about 20 cm are. The optical axes of at least two cameras can approximate oriented in the same direction, with a smaller angular deviation of a maximum of 5 degrees to each other.

At least two cameras can be equipped with panning mechanism, with which the cameras can be pivoted together remotely relative to the helicopter. The pivoting movements of preferably exactly two cameras can be coupled, z. B. logical, electrical or mechanical.

at The mechanics for panning a camera are many design variants. The mechanics can swing movements of at least two cameras to enable axes the approximate lie parallel to the transverse axis of the helicopter. By "approximately parallel" is meant that the axes are inclined no more than 20 degrees to each other, preferably not more than 5 degrees. The axes may be particularly preferred with each other aligned.

at The pivoting movement of a camera can have different degrees of freedom be used. Or even a single one.

Of the Swing mechanism may include a rowing machine. The rotation axis the output of a rowing machine can simultaneously also a rotation axis represent a pivoting movement of a camera. The storage of the The output of a rowing machine and the bearing of the swivel mechanism of a camera can be identical be. A camera can be mounted on the output of a rowing machine be.

The optical axis of a camera (camera optics axis, recording direction) can approximate in a camera position in the hover of the helicopter lie horizontally, z. For example the camera view to the front ("cockpit view"). The optical axis can approximate in a camera position parallel to the longitudinal axis of the helicopter. A camera can preferably be pivoted in such a way accomplished be that the optical axis in a camera position down obliquely is directed, or vertically downwards.

To a further embodiment According to the invention, a camera may be a so-called board camera or include such. Here is the camera optics directly a (small) evaluation electronics (board) connected - a compact Lightweight construction.

Further Is it possible, a vibration-proof camera to attach the helicopter to for example, image blurs to prevent by mechanical vibrations.

Weight and size of the helicopter can vary. Preferably a take-off mass is below about 5 kg, more preferably below about 1 kg. The largest dimensions may preferably be below about 1.2 m.

Of the Helicopters may also be electrically powered. He can with three or more lifting units each having at least one rotor and be formed at least one rotor driving the electric motor.

• • Übertragung der Kamerabilder per Funk zum Boden;
• • Darstellen der Kamerabilder mit einem bildgebenden System, und zwar für das rechte Auge eines Betrachters das Bild einer Kamera und für das linke Auge desselben Betrachters das einer anderen Kamera; und
• • Anfliegen eines zu beobachtenden Zielobjekts mithilfe von Kamerabildern.

According to the invention, a method is also provided for observation from the air by means of a radio-controlled helicopter, wherein at least two cameras with a distance of 5 cm to 50 cm are provided on the helicopter whose optical axes are oriented approximately in the same direction (with a maximum deviation of 20 Degree to each other). The procedure contains the steps:

• • transmission of the camera images by radio to the ground;
• • displaying the camera images with an imaging system, for one viewer's right eye the image of one camera and for the left eye of the same observer that of another camera; and
• • Approaching a target to be observed using camera images.

The camera images of two displayed by an imaging system Cameras can create a three-dimensional image impression in the viewer.

Prefers can two remote-controlled swivel cameras together on a target object be aligned by remote control.

The Method can be used in urban environment, preferably in a radius of about 1 km.

Short description the drawings

Further Aspects and advantages of the invention will become apparent from the following Description of preferred embodiments, which will be explained with reference to the following figures.

1 shows a plan view of a four-rotor helicopter with two cameras according to a first embodiment of the invention;

2 shows a longitudinal sectional view of the helicopter after 1 ;

3 shows an enlarged section of 1 ;

4 shows an enlarged section of 2 ;

5 shows a representation like 4 but with a different camera position;

6 shows a representation like 4 but with another camera position;

7 shows an enlarged section like 3 according to a second embodiment of the invention; and

8th shows a viewer of the camera images.

description preferred embodiments the invention

To a preferred embodiment the invention provides a specific type of helicopter, namely those with three or more lifting units (so-called multi-rotor helicopters). Under lifting unit, the combination of at least one rotor with understood at least one motor driving the rotor. The lifting units can also contain other components, eg. B. gear or speed controller. The combination of exactly one rotor with exactly one motor is the most frequent execution a lifting unit. The axes of the rotors are typically (approximately) vertical. The rotors serve primarily the lift generation - therefore the name lifting unit.

highlight is the 4-rotor helicopter, which has system-related advantages and whose economic benefits are increasing, accelerated by current ones Developments of improved attitude stabilization techniques, which are particularly effective in this helicopter type to let. Among the advantages of the 4-rotor concept is the possibility a controller to all axes alone about the speed of four rigid Rotors, so without mechanics except rotating shafts, in particular without collective and cyclic rotor blade adjustment (see following table). 4-rotor helicopters can accordingly be built mechanically very minimalist.

Note: In the example according to the table, the 4 rotors are "on axis", in the exemplary embodiment 1 offset by 45 degrees.

In the plan view are the lifting units of 4-rotor helicopters almost always arranged at the corners of a square, often at the corners a square. The center distances are usually so big that the circular surfaces defined by the rotors are straight do not overlap. With that you can the rotors are arranged on one level without touching each other.

Out establish For aerodynamic efficiency, the rotors should be rather large in diameter have (low circular surface load). This requirement competes with the pursuit of compact dimensions.

The 1 and 2 show a speed-controlled, 4-rotor helicopter 1 , which is suitable for aerial observation in urban terrain. The helicopter 1 comprises a total of four lifting units 2 , The lifting units 2 each have one in the embodiment zweiblättrigen rotor 3 and an electric motor driving the rotor 4 , The lifting units 2 are on a support frame 11 attached and connected by this. The shoring 11 also carries a central control unit 12 and two cameras 5 ,

In the control unit 12 Two separate transmitters are integrated for the radio transmission of the camera images to the ground, a receiver for receiving the remote control signals from the ground, electronics for stabilizing the attitude and for controlling the lifting units and the central power supply (rechargeable battery).

The execution With two separate transmitters has the advantage of being on market components resorted can be. That applies to the entire chain of camera, transmitter and receiver (for receiving the camera images on the ground). requirement for this solution is that each chain works on a different frequency. Another Advantage: The image transfer is redundant. In case of failure of a component or a radio interference is only one chain affected. The other one provides further image information.

alternative can However, functions are summarized, for. B. by weight to save. So can two cameras are combined with a transmitter and a receiver.

The technical data of the helicopter 1 are as follows: Rotor diameter: 380 mm Power requirement (hover): 25 W Flight time: 20 min Take-off weight: 350 g Dimensions over everything (length, width): 800 mm Camera distance s: 130 mm

With the two cameras 5 These are board cameras. The camera optics are each directly on the board 6 attached ( 3 ), which houses the electronics belonging to the camera. Such a unit weighs only about 20 g, depending on the quality.

The board 6 turn is directly on the rotary drive 8th the rowing machine 7 (Servo) held.

The rowing machines 7 are about the vibration isolation 13 on the support frame 11 attached. The vibration isolation 13 are made of a soft, vibration-damping material. This disturbing vibrations are kept away from the cameras.

With rotation of the output 8th the rowing machine 7 is also the attached camera 5 pivoted. Thus, the camera is pivotable about an axis that is oriented parallel to the transverse axis of the helicopter. The arrangement allows depending on the position of the rotary drive 8th a camera view horizontally forward, ie in the direction of the longitudinal axis of the helicopter (cockpit view, 4 ), sloping downwards ( 5 ), or vertically downwards ( 6 ). Optionally, other camera positions are possible, for. B. Look up.

The pivot bearing of camera 5 and downforce 8th are identical. For storage of the camera 5 No effort is required because the storage with the rowing machines 7 already included. The Lö The solution is mechanically simple, low-friction and low-weight at the same time.

With the flexible electrical wires 14 are the cameras 5 and the rowing machines 7 with the central control unit 12 electrically connected. The cables are inside the shoring 11 laid.

The horizontal opening angle of the camera optics in the exemplary embodiment is 40 degrees, the vertical 30 degrees. This data becomes the viewer on the ground 9 provided a realistic cockpit view from the helicopter ("natural image").

In the embodiment, two cameras are present to the viewer 9 ( 8th ) to convey a three-dimensional impression. For this purpose, the optical axes of the two cameras are parallel, with a distance of 130 mm. The parallelism is ensured even when the cameras are rotated, because the rowing machines are moved synchronously. Both cameras thus take (almost) the same picture, but from a slightly different perspective. The viewer 9 carries an imaging system 17 at the head. The right eye of the viewer is offered the image of the right camera, the left eye of the left camera. The result is a three-dimensional image impression in the viewer, with which he can estimate distances much better. He can control the helicopter safer, especially obstacles easier to detect and avoid.

Of the in the embodiment provided distance of the two cameras of 130 mm is slightly larger than the human eye distance. This is the 3D effect over the reinforced normal view. The bigger the Camera distance, the easier it can be also different, larger distances be differentiated. However, if the camera distance is too great, in the near-sight unpleasant "distortions" - sometimes goes the 3D image impression entirely lost. 130 mm is a cheaper one Value. Depending on the distance of the target objects and depending on viewing habits can however, other values may be useful.

optional a camera can also be provided with a housing. The housing can also surrounded several cameras. It can, for example, two cameras combined into a "stereo camera" be.

7 shows a variant of the camera pivoting mechanism. Compared to the solution 3 is a rowing machine 7 saved. Both cameras 5 are moved with a single steering machine. The cameras 5 with the boards 6 are on the pipe 16 attached and connected. The right end of the tube is at the output 8th the rowing machine 7 held, the left in the camp 15 rotatably guided. The weight of the complete swing mechanism after 7 amounts to 8 g including rowing machine ( 3 : 11 g).

The airborne observation with the presented system may look like this: the operator and the viewer 9 ( 8th ) controls the aircraft manually with a remote control transmitter on the basis of the camera images, which are constantly in real-time close to the imaging system 17 be fed. He sees the surroundings of the helicopter as if he were sitting in it. For normal flight operations, the cameras are oriented horizontally (as in 4 ) or (slightly) downwards ( 5 ).

Because the camera is not tilted to the right or left, just to is an axis parallel to the transverse axis can be pivoted is the operator always in the picture, where the helicopter is in front, namely in the middle of the picture. This considerably simplifies the control.

One Control command "after for example, fly in the front always leads that the helicopter on the target object shown in the picture too moved. Control command "right" executes View of the operator always to a flight movement to "right". With the other Functions it is analog. A "reversal" from right / left or front / back does not take place.

For the look to the right and left is the whole helicopter around its vertical axis rotated (yaw function). In this way, the operator can be at any time provide a 360 ° view without the need for an additional swivel mechanism for one Camera would be required (Implementation of the minimal principle by combination of functions).

Especially with this control function, the advantages of the 4-rotor helicopter come to fruition. The yaw function is decoupled from the other control functions. Any command (pitch, roll, yaw, or up / down) of the helicopter does not require another command to compensate for side effects. (Conventional helicopters, on the other hand, are known for such unwanted couplings.) Example: Up / down changes torque compensation required by tail rotor.) Also the 4-rotor helicopter has no preferred flight direction as conventional types. It can be moved forwards / backwards, right / left alike. This makes it possible to rotate the helicopter at any time in such a position about its vertical axis, that the desired scenery can be seen in the camera image. The helicopter can stay in one place flying (hovering), moved forward, backward or sideways, with always neutral control behavior, in particular without automatically aligning forward in the direction of flight. (The propensity to "fly ahead" is familiar from conventional helicopters because of the wind vane effect of the tail boom and tail rotor.)

This special flight behavior of 4-Rotorenhubschraubern remains at Wind received (assuming the flow velocity at the helicopter is below the design airspeed). The hover is possible in any wind direction, without disturbing moments around the vertical axis. (Conventional helicopters are spinning more or less in the wind.)

When maneuvers the helicopter of the invention may be mentioned as an example: persecution of a fugitive bank robber in the city (forward flight). "Flying off" the park rows of a Parking garage with identification of the license plates (cross-flight). Circle of a target object, e.g. B. a burning building that is permanently in the picture remains (cross flight with rotation).

At the embodiment was the pivoting of the camera with only a single degree of freedom implemented, namely Pan about a transverse axis. Alone with this degree of freedom can - in combination with the greed function of the helicopter - the camera in every possible Attitude can be turned in any direction (implementation of the Minimal principle by dispensing with unnecessary degrees of freedom).

Opposite the Alternative, several (rigidly mounted) cameras for different To use directions, the concept presented has with swiveling Cameras advantages in costs and weight.

The Cameras are mounted close to the helicopter (important because of inertia, Overall center of gravity and flight behavior), with virtually unlimited visibility in all relevant directions. (Only the rotor blades comb the picture at certain Camera positions.)

The Pivoting the cameras makes valuable service in flight operations. For the Cruise flight (forward), the cameras are preferably horizontal Align to the front, at high airspeed possibly to the longitudinal axis slightly upward to the "tilt" of the helicopter in the high-speed flight too compensate. Some target objects can only be viewed from above, for example, a courtyard between buildings. Here you become the cameras temporarily put in a vertical position. A cheap camera position for many Flight situations is slightly inclined downwards. You can see in the bottom Picture part of the underground (important when landing) and in the upper just the horizon (helpful for orientation).

• a) Rollen, Nicken und Auf/Ab dienen vornehmlich der Bewegung des Fluggeräts im Raum.
• b) Mit Gieren und Schwenkwinkel wird im Raum „optisch navigiert" und das jeweilige Zielobjekt fokussiert (Gieren für „rechts-links-scrollen", Schwenkwinkel für „rauf-runter-scrollen).

The operator controls a total of 5 functions: Rolling, pitching, yawing, up / down and the tilt angle of the camera (s). These functions can be divided into 2 classes:

• a) Roll, pitch and up / down serve primarily the movement of the aircraft in space.
• b) With yaw and swivel angle in the room "visually navigated" and focused the respective target object (yaw for "right-left-scroll", swivel angle for "up-down-scroll).

The Experience has shown that these 5 functions of a single Operators can be controlled simultaneously, especially if the two functional classes are distributed to different controls. Would be more Functions implemented (eg additional camera adjustment options) would be the Operator overwhelmed, depending on the flight task. The operability is decisively influenced by the Flight characteristics and the helicopter's control behavior. With 4-rotor helicopters have achieved the best results.

The Work of the operator may be through additional equipment and electronic Helps (advanced attitude stabilization, GPS, zoom function on cameras etc.) and be relieved.

at many uses in urban terrain allowed by the aircraft no danger, neither to persons nor to things (Vehicles, buildings Etc.). Also in this point impresses in the embodiments presented helicopters. The kinetic energy in a crash is small, because of the low take-off weight of only 350 g.

Also at the risk potential Due to the rotating rotors, the presented concept has advantages. 4 small rotors are less dangerous as a big one like the conventional helicopter. The respective drive power (here about 6 W) is much smaller and the rotors are much lighter (here about 7 g). Both together causes the rotors without serious Injuries can be stopped by hand. (In the conventional Helicopters, on the other hand, are at considerable risk from the main rotor out. Rotor mass and mass moment of inertia rise disproportionately with the diameter. In addition, conventional rotors often very targeted with higher Moment of inertia be designed to improve the autorotation properties. Sometimes even more Weights attached.) The hazard potential in the helicopter of the invention can be further reduced by collision protection systems (eg with on the support frame retained protective rings or protective straps on the rotors).

Conclusion: The helicopter according to the invention with at least two cameras in a particular arrangement meets the Requirements for an aircraft for obtaining optical information from the air in an ideal way. The three-dimensional image greatly facilitates the control.

Especially advantageous is the embodiment as a multi-rotor helicopter. All-round visibility is in all directions and possible in every flight situation. The helicopter is easy to control, light, energy efficient, inexpensive, reliable, quiet and safe. It is universally applicable, even in urban areas, on the narrowest Space, between obstacles, over Crowds and inside buildings. Moving targets can be tracked become.

1

helicopter

2

lifting unit

3

rotor

4

electric motor

5

camera

6

circuit board

7

rowing machine

8th

output

9

observer

11

shoring

12

control unit

13

vibration isolation

14

electrical management

15

camp

16

pipe

17

imaging system

Claims (25)

Unmanned, radio-controlled helicopter ( 1 ) for observation from the air, whereby at the helicopter ( 1 ) at least two cameras ( 5 ) are provided with a distance of 5 cm to 50 cm, the optical axes are oriented approximately in the same direction, with an angular deviation of a maximum of 20 degrees to each other. Helicopter according to claim 1, characterized in that for two cameras ( 5 ) a transmitter is provided for radio transmission of the camera images. Helicopter according to claim 1 or 2, characterized in that the optical axes of at least two cameras ( 5 ) at a distance of about 7 cm to about 20 cm. Helicopter according to one of claims 1 to 3, characterized in that the optical axes of at least two cameras ( 5 ) are oriented approximately in the same direction, with an angle deviation of a maximum of 5 degrees to each other. Helicopter according to one of claims 1 to 4, characterized in that at least two cameras ( 5 ) are provided with pivoting mechanism, with which the cameras ( 5 ) relative to the helicopter ( 1 ) can be pivoted together remotely. Helicopter according to claim 5, characterized in that the mechanism pivotal movements of at least two cameras ( 5 ) about axes that are approximately parallel to the transverse axis of the helicopter ( 1 ) lie. Helicopter according to claim 5 or 6, characterized in that for the pivoting movement of a camera ( 5 ) a single degree of freedom is provided. Helicopter according to one of claims 5 to 7, characterized in that the mechanism for pivoting a camera ( 5 ) a rowing machine ( 7 ) contains. Helicopter according to claim 8, characterized in that the axis of rotation of the output ( 8th ) of a rowing machine ( 7 ) at the same time a rotation axis of a pivoting movement of a camera ( 5 ). Helicopter according to claim 8 or 9, characterized in that the bearing of the output ( 8th ) of a rowing machine ( 7 ) at the same time a bearing of the pivot mechanism of a camera ( 5 ). Helicopter according to one of claims 8 to 10, characterized in that a camera ( 5 ) at the output ( 8th ) of a rowing machine ( 7 ) is attached. Helicopter according to one of claims 1 to 11, characterized in that the optical axis of a camera ( 5 ) in a camera position in the hover of the helicopter ( 1 ) is arranged approximately horizontally. Helicopter according to one of claims 1 to 12, characterized in that the optical axis of a camera ( 5 ) is arranged in a camera position approximately parallel to the helicopter longitudinal axis. Helicopter according to one of claims 1 to 13, characterized in that the optical axis of a camera ( 5 ) in a camera position in the hover of the helicopter ( 1 ) is arranged obliquely downwards. Helicopter according to one of claims 1 to 14, characterized in that the optical axis of a camera ( 5 ) in a camera position in the hover of the helicopter ( 1 ) is arranged approximately vertically. Helicopter according to one of claims 1 to 15, characterized in that a camera ( 5 ) is a board camera or contains such. Helicopter according to one of claims 1 to 16, characterized in that a camera ( 5 ) isolated from the helicopter ( 1 ) is attached. Helicopter according to one of claims 1 to 17, characterized in that the take-off mass of the helicopter ( 1 ) does not exceed about 5 kg, more preferably does not exceed about 1 kg. Helicopter according to one of claims 1 to 18, characterized in that the largest dimension of the helicopter ( 1 ) does not exceed about 1.2 m. Helicopter according to one of claims 1 to 19, characterized in that the helicopter ( 1 ) is electrically driven. Helicopter according to claim 20, characterized in that the helicopter ( 1 ) with three or more lifting units ( 2 ) each having at least one rotor ( 3 ) and at least one rotor ( 3 ) driving electric motor ( 4 ) is trained. Airborne surveillance using a radio-controlled helicopter ( 1 ), whereby the helicopter ( 1 ) at least two cameras ( 5 ) are provided at a distance of 5 cm to 50 cm, the optical axes are oriented approximately in the same direction, with a maximum deviation of 20 degrees, comprising the steps of: • transmission of the camera images by radio to the ground; • Display the camera images with an imaging system ( 17 ), for the right eye of an observer ( 9 ) the image of a camera ( 5 ) and for the left eye of the same observer that of another camera ( 5 ); and • approaching a target object to be observed using camera images. A method according to claim 22, characterized in that two remotely controlled pivotable cameras ( 5 ) are aligned together to a target object by remote control. Method according to claim 22 or 23, characterized that the method is used in an urban environment. Method according to one of claims 22 to 24, characterized in that the helicopter ( 1 ) no more than about 1 km from the viewer ( 9 ) flies away.