GB2532841A

GB2532841A - Carrier system

Info

Publication number: GB2532841A
Application number: GB1515920.5A
Authority: GB
Inventors: Vogel Holger; Szczuka Gunther
Original assignee: Airbus DS Optronics GmbH
Current assignee: Hensoldt Optronics GmbH
Priority date: 2014-11-25
Filing date: 2015-09-08
Publication date: 2016-06-01
Anticipated expiration: 2035-09-08
Also published as: GB201515920D0; DE102014117277A1; GB2532841B; DE102014117277B4

Abstract

A carrier system 1, with a position-stabilized component 2; an imaging sensor 2a, which is designed to continuously detect image signals of a region surrounding the carrier system 1, a position sensor 3; stabilization means 5 for continuously stabilizing the position and/or the alignment of the component 2 and the imaging sensor 2a or at least the line of sight LOS thereof depending on measurement signals m_s of the position sensor 3. Image processing means 6 are designed to automatically determine a present drift of the position sensor 3 from the image signals v_s detected by the imaging sensor 2a. The carrier system 1 is designed to automatically at least approximately correct and/or compensate for the present drift of the position sensor 3 determined by the image processing means 6, in particular by means of the stabilization means 5. The carrier system is suitable for use on a moving carrier such as vehicles, ships, aircraft, buoys, masts etc. The drift may be determined by a global movement of the scene recorded by the imaging sensor.

Description

Description:

Carrier system The invention relates to a carrier system, to a method for determining a drift of a position sensor, and to a method for continuously stabilizing the position and/or the alignment of a component.

Components such as, for example, vision systems in or on moving carriers, in particular vehicles, ships, aircraft, buoys, masts, etc. should be stabilized with regard to their position and/or alignment particularly if these systems are having small fields of view. If such position stabilization is absent, then an observation during the movement of the carrier or the base is not possible or is possible only with difficulty or the visual range can be adversely influenced. It is known to arrange such components in carrier systems which are provided with in particular inertial measurement position sensors, preferably angular position sensors (e.g. gyroscope sensors / mechanical gyroscope sensors) or angular rate sensors, (e.g. gyrometers), which detect the movement of the Line Of Sight (LOS). In this case, a downstream stabilization controller in conjunction with corresponding actuators for axial rotation (e.g. motors or the like) can compensate for the rotational movement in such a way that the line of sight remains constant independently of the intrinsic movements of the reference area, i.e., of the fixing point of the vision system or of the component or of the carrier system to the carrier. In this case, such carrier systems can be embodied as part of the carrier or can be fitted on the carrier or connected thereto, e.g., by means of a suitable fixing device (fixing flange or the like).

Position sensors, in particular angular position sensors or angular rate sensors, in a wide variety of technologies are known. These include, for example, mechanical inertial gyroscopes, fibre-optic gyroscopes (FOG), laser gyroscopes or modern 30 MEMS (Micro-Electro-Mechanical Systems) gyroscopes.

However, such sensors exhibit an -albeit small -intrinsic drift. Said intrinsic drift is dependent on various characteristic, individual and dynamic factors. The gyroscope technology used, component variations, temperatures or even ageing play a part here.

On account of said intrinsic drift, a line of sight of a vision system which is stabilized by means of an angular position sensor or angular rate sensor does not remain constant for a longer period, but rather moves gradually away from the original alignment.

In order to keep a set observation position constant, said drift should be prevented or eliminated. Systems known from the art compensate for the drift by the user setting a correction manually, e.g., separately for each axial direction. Although this procedure significantly reduces the drift, the drift of the position sensors also contains a component that varies depending on the temperature, for example, such that the manually set drift compensation cannot achieve success that remains constant for a longer period. The user must disadvantageously intervene again and manually compensate for the drift once again. Since, in particular, angular position sensors or angular rate sensors are inertial measurement sensors, the rotation of the Earth likewise has an influence on the drift. This influence is dependent on the degree of latitude and, with regard to the angle of elevation, also dependent on the azimuthal viewing direction of the line of sight. In this regard, by way of example, the influence of the rotation of the Earth on the elevation axis is reversed upon an azimuthal rotation by 180°. Accordingly, an azimuthal rotation requires a renewed adjustment of the drift with regard to elevation.

An automatic drift adjustment wherein the gyroscope drift is detected with a carrier system at a standstill is likewise already known. For this purpose, however, it is absolutely necessary for the platform reference area or the carrier (e.g. in the form of a land vehicle/sea craft/aircraft, a mast, a buoy, etc.) to be at a standstill. An external high-quality reference gyroscope system, such as a navigation installation, for example, may likewise be necessary in the case of an automatic drift adjustment.

Usually it is not possible to achieve a standstill of the carrier or of the carrier system at least during operation, since this may be at odds with a predefined mission goal in the case of land vehicles or aircrafts. On a maritime carrier such as, for example, a boat, a ship or a buoy, a complete standstill of the carrier system is practically 5 impossible on account of the generally prevailing swell of the sea. For high masts, it is likewise not always possible to keep the carrier platform steady on account of wind movement. Previous methods using support data of a navigation platform fail in part owing to the inadequate performance of the navigation platform used. Higher-quality navigation platforms are often not considered for cost reasons. Moreover, after an to azimuthal rotation, the drift is detuned again by the latitude-dependent influence of the rotation of the Earth.

In the case of optronic vision systems, replacing the gyroscope stabilization by a digital image stabilization is not practicable since this leads to a lower stabilization quality and to reduced ranges, which is unacceptable in most systems. Moreover, the dynamic range (governed by the amplitude of the disturbances) is smaller in this case. Furthermore, the system with use of a digital image stabilization and mechanically coupled vision or active systems is not suitable for direction-finding and targeting applications. Moreover, the processing of the images additionally gives rise to a time delay of the displayed image, which is often not tolerable.

Proceeding from this, the present invention is based on the object of providing a carrier system of the type mentioned in the introduction which avoids the disadvantages of the prior art, in particular wherein the drift of a present position sensor during dynamic operation of the carrier system can be reliably determined and, if appropriate, compensated for.

According to the invention, this object is achieved by means of a carrier system, at least comprising: -a position-stabilized component; -an imaging sensor, which is designed configured to continuously detect image signals of a region surrounding the carrier system; - an, in particular inertial, position sensor; - stabilization means for continuously stabilizing the position and/or the alignment of the component and the imaging sensor or at least the line of sight thereof depending on measurement signals of the position sensor; and -image processing means, which are designed configured to automatically determine a present drift of the position sensor from the image signals detected by the imaging sensor, wherein - the carrier system is designed configured to automatically at least approximately correct and/or compensate for the present drift of the position sensor determined by 10 the image processing means, in particular by means of the stabilization means.

The measures according to the invention make it possible to realize an automatic drift compensation or a drift adjustment during operation or during the travel or movement of the carrier system or of the associated carrier (e.g. a vehicle). This is preferable to a drift compensation with the carrier system at a standstill, since this significantly improves the general utilization. A standstill of the platform reference area or of the carrier is thus advantageously not necessary. The drift compensation can be carried out during dynamic operation, that is to say with movement of the platform reference area (e.g. vehicle movement). The drift compensation can automatically correct the latitude-dependent influence of the rotation of the Earth on the drift in the case of a rotation. An external high-quality reference gyroscope system such as, for example, a navigation installation or the like is not required. Accordingly, a dynamic compensation of the drift of a stabilized platform on the basis of scene data is provided. The scene data are taken from the imaging sensor, the line of sight of which is inertially stabilized by the stabilizing system. A visual sensor (camera), a thermal sensor (thermal imaging device or the like), a radar sensor (radar scene) or some other sensor that images passively or actively in the electromagnetic spectrum may be appropriate as the imaging sensor. As a result of the automatic drift compensation according to the invention, it is generally possible to employ gyroscopes whose drift property has a low stability, without the region under consideration gradually being left. Considerable costs can be saved as a result.

Claim 13 specifies a method, in particular for continuously automatically determining a drift of a position sensor, in particular during dynamic operation, wherein: - at least one imaging sensor or at least the line of sight thereof is stabilized with regard to position and/or alignment depending on measurement signals of the 5 position sensor, and wherein - in image signals of the at least one imaging sensor, at least one global movement of the scene recorded by the at least one imaging sensor is detected within a predefinable time interval, from which the drift of the position sensor is determined.

The object of the invention is likewise achieved by means of the method specified in Claim 17. Claim 17 relates to a method for in particular continuously automatically stabilizing the position and/or the alignment of a component, in particular during dynamic operation, by means of stabilization means on the basis of measurement signals obtained by a position sensor, wherein a drift of the position sensor is determined continuously by means of the method according to the invention for determining a drift of a position sensor, and whereupon, if the drift of the position sensor is present, the latter is at least approximately or completely corrected and/or compensated for, in particular using the stabilization means.

The method according to the invention for continuously stabilizing the position of a component can advantageously also be used as an optional accessory or add-on for new installations, and also for retrofitting already existing installations.

It is advantageous if the image processing means are designed configured to determine the present drift of the position sensor from and/or depending on a global movement of the scene recorded by the image sensor, in particular within a predefinable or variable time interval.

The scene data of the imaging sensor can thus be analysed with regard to scene movements by means of an image processing. On the basis of the image content, a global movement over a relatively long time is identified, which is subsequently used for automatic drift compensation. In this case, the time interval can be fixedly predefined or be determined variably.

The carrier system can be designed configured to convert the global movement of the scene recorded by the imaging sensor into an angular movement of the imaging sensor.

The global movement determined from the scene can be converted to an angular movement of the camera by means of the field of view resolution.

In the case of the carrier system, a drift controller unit can be present, which is designed configured to form a drift compensation signal from the global movement of the scene recorded by the imaging sensor or from the angular movement of the imaging sensor.

The determined global movement of the scene or the angular movement of the camera can be fed to a drift controller unit, which forms therefrom a compensation value that can be used to eliminate the drift of the position sensor.

The carrier system can be designed configured to at least approximately or completely correct and/or compensate for the drift of the position sensor contained in the measurement signals of the position sensor by means of the drift compensation signal of the drift controller unit, in particular before the measurement signals of the position sensor are fed to the stabilization means.

In order to achieve a sufficient steadying of the component or of the line of sight of 25 the component, the intrinsic drift contained in the output signal of the position sensor can be compensated for upstream of the stabilization controller.

The drift controller unit can be designed configured to track adjust the drift compensation signal, in particular with a large time constant.

The drift controller can thus control the scene movement to zero by tracking the drift compensation signal, in particular with a large time constant. The stabilization means can compensate for temporally rapidly changing movements of the carrier system, while the drift controller only corrects the temporally sluggishly changing drift movements.

Advantageously, the image processing means can be designed configured, for the purpose of determining the global movement of the scene recorded by the image sensor, to determine at least one static region in an image detected by the imaging sensor, which is subsequently tracked by means of an object tracking or a method for object tracking.

In this case, an identified static region in the scene can be transferred to an object tracking. Methods for object tracking are sufficiently known from the prior art. Said object tracking can then track the position of a manually defined or a previously identified and automatically learned static region in the scene and forward the position changes identified in this case, preferably after having been subjected to temporal low-pass filtering, to the drift controller unit for compensation.

Consequently, the global movement and thus the present drift of the position sensor can be determined using simple means.

The image processing means can be des-i-g-ned-configuced, for the purpose of determining the global movement of the scene recorded by the imaging sensor, to use or to compare at least two images detected by the imaging sensor in a time interval, in particular of 0.01 second to 1 hour, preferably of 1 second to 60 seconds.

The calculation of the global movement or of the global drift can be carried out, for instance, by means of a method for determining a sensor self-movement as disclosed in EP 1 441 316 A2. A consideration temporally further apart can be used in the present case. At least two images of the imaging sensor in a time interval of 0.01 second to 1 hour, preferably of 1 second to 60 seconds, can be used for this purpose. The at least two images can then be subjected to low-pass filtering and be converted into the frequency domain by means of a Fast Fourier Transform (FFT). They can be convolved there, which corresponds to a correlation in the spatial domain, and the result can be transformed back into the spatial domain again by means of a reverse FFT. In the result image that arises therefrom, the results of all the correlations are indicated as grey-scale values. The position of the brightest grey-scale value in the result image accordingly corresponds to the shift of the second 5 image relative to the first image of the imaging sensor and thus to the drift of the stabilization system or of the position sensor in the time period between the two recordings. The global movement of the scene recorded by the imaging sensor or the drift vector can be converted into an angular movement of the imaging sensor or into an angle value on the basis of the current field of view and can be fed to the drift to controller and thereby corrected.

Consequently, for the purpose of determining the global movement of the scene recorded by the imaging sensor: - at least two images detected by the imaging sensor in a time interval, in particular of 15 0.01 second to 1 hour, preferably of 1 second to 60 seconds, can be used and/or compared with one another; and/or - at least one static region can be determined in an image detected by the imaging sensor, which is subsequently tracked by means of an object tracking. Therefore, two alternative procedures are available, which can also be combined with one another. 20 A drift compensation signal can be formed from the global movement of the scene recorded by the imaging sensor or from the angular movement of the imaging sensor. The drift of the position sensor contained in the measurement signals of the position sensor can be at least approximately or completely corrected and/or compensated for by means of the drift compensation signal before the measurement signals of the position sensor are fed to the stabilization means. The drift compensation signal can be tracked, in particular with a large time constant.

It is very advantageous if the determined global movement of the scene recorded by 30 the imaging sensor is checked for plausibility, in particular using a differential image.

In the case of extreme movements in the scene, incorrect calculations of the displacement vector can possibly occur. It is thus advantageous to identify such incorrect calculations and then not to use them for stabilization or for compensation of the drift. This can be carried out, e.g., by means of a locally tolerant subtraction in a so-called nine-cell neighbourhood of both images with a detection threshold taking account of the displacement vector determined. In digital image processing, a neighbourhood means a small, defined image region around a pixel, wherein each pixel of an image has four, horizontal and vertical, neighbours distinguished by the fact that they respectively share a pixel edge with the pixel. Furthermore, each pixel of an image also has four diagonal neighbours that share only a corner with the pixel.

Accordingly, this can be referred to, e.g., as a four-cell neighbourhood or an eight-cell neighbourhood. The nine-cell neighbourhood used in the present case is an eight-cell neighbourhood which was extended by the middle or central pixel. Pixels arranged at corner points or edges of an image can have correspondingly fewer neighbours. In the case of correct calculation and little movement, markings can hardly be found in a differential image created in this way. If a large part of the differential image is marked as difference, then the calculation has failed and the result should not be used, in which case a new calculation should be carried out. In the case of local regions having differences, a movement took place in the scene. Starting from a limit value that can be set, e.g., between approximately 5% and approximately 50%, of the proportion of this local movement in the image, either this calculation, too, can no longer be used or the calculation must be carried out again with these regions being masked out. Since the drift compensation is carried out at relatively long time intervals and, therefore, is nowhere near being subject to video real-time requirements, such iterative or repeated calculations can be carried out without problems in the event of errors.

In one embodiment of the invention, the stabilization means can comprise: -drive means in order to carry out an, in particular defined, movement of the position-stabilized component; and -a stabilization controller unit, which is communication-connected to the drive means and the position sensor and which receives the measurement signals of the position sensor as input signals and which is designed configured to control an inertial rotational movement present in the measurement signals of the position sensor to zero by driving the drive means in such a way that the position-stabilized component and in particular the position sensor are adjusted.

By means of this measure, the movement of the carrier system is compensated for and the component or the line of sight thereof is stabilized.

The, in particular inertial, position sensor can be embodied as an angular position sensor (e.g. gyroscope sensor, mechanical gyroscope or the like) or as an angular rate sensor (e.g. gyrometer or the like). Position sensors of arbitrary or different technologies are suitable, e.g. mechanical inertial gyroscopes, fibre-optic gyroscopes, laser gyroscopes or modern MEMS gyroscopes.

The position-stabilized component can comprise the at least one imaging sensor or 15 an element which stabilizes the line of sight of the imaging sensor.

The position-stabilized component can be an optronic vision system.

During a manual directing process for the optronic vision system (changing the line of sight/LOS), the drift controller unit or the drift compensation can be stopped in order to prevent an incorrect compensation. After the conclusion of the directing process, the newly chosen line of sight and the scene to be newly detected are used as reference.

Advantageous embodiments and developments of the invention are evident from the dependent claims. An exemplary embodiment of the invention is described in principle below with reference to the drawing.

In the figures: Figure 1 shows a schematic illustration of the effective principle of a carrier system according to the invention; Figure 2 shows a schematic illustration for clarifying a global image movement or a drift in an image; Figure 3 shows a schematic illustration for elucidating a small local moved region; and Figure 4 shows a schematic illustration of a carrier system according to the invention.

In the figures, functionally identical elements are provided with the same reference signs.

Figure 1 clarifies the effective principle of the automatic drift compensation according to the invention on the basis of one axis. In this case, on the basis of the image content, a global movement over a relatively long time is identified and this movement is used as additional compensation. Figure 1 shows a carrier system 1, which is arranged on an, in particular movable, carrier 10b (e.g. a vehicle) by means of a fixing device 10a (e.g. a fixing flange or the like). In further exemplary embodiments (not illustrated), the carrier system 1 could also be part of an, in particular movable, carrier or of an, in particular movable, base. The carrier system 1 comprises, as position-stabilized component, an optronic vision system 2 having a camera (e.g. in the visual range) as imaging sensor 2a, which is designed configured to continuously detect image signals of a region surrounding the carrier system 1. In other exemplary embodiments, the imaging sensor can also be embodied as a thermal imaging device. Furthermore, the optronic vision system 2 can also comprise a plurality of, in particular different, imaging sensors. A line of sight LOS of the imaging sensor 2a is indicated as a dashed arrow in Figure 1. The carrier system 1 furthermore comprises a position sensor, embodied as an angular rate sensor 3. In further exemplary embodiments, a different position sensor, e.g., an angular position sensor, could also be used here. In the present exemplary embodiment, the optronic vision system 2 comprising the imaging sensor 2a and the angular rate sensor 3 are arranged on a stabilized platform 4. In further exemplary embodiments (not illustrated), with the necessary changes, a stabilized platform 4 or the like could also be dispensed with. In this case, the carrier system could serve for stabilization. The angular rate sensor 3, as indicated in Figure 1, can have a drift or an intrinsic drift.

The carrier system 1 furthermore comprises stabilization means 5 for continuously stabilizing the position of the optronic vision system 2 and of the imaging sensor 2a or at least the line of sight LOS thereof depending on measurement signals m_s of the angular rate sensor 3 (in rad/s), which can have an inertial rate of rotation, in particular with a drift. The carrier system 1 furthermore comprises image processing means 6, which are designed configured to automatically determine a present drift of the angular rate sensor 3 from the image signals v_s detected by the imaging sensor 2a and forwarded to the image processing means 6. The carrier system 1 is designed configured to automatically at least approximately or completely correct and/or compensate for the present drift of the angular rate sensor 3 determined by the image processing means 6, in particular by means of the stabilization means 5.

The stabilization means 5 comprise drive means 5a embodied as a motor, preferably an electric motor, in order to carry out a movement of the stabilized platform 4 or of the position-stabilized component or of the optronic vision system 2, and a stabilization controller unit 5b, which is communication-connected to the drive means 5a, and the angular rate sensor 3 and which receives the measurement signals m_s of the angular rate sensor 3 as input signals and which is de-Sig-Red configured to control an inertial rotational movement present in the measurement signals m_s of the angular rate sensor 3 to zero by driving the drive means 5a, in such a way that the optronic vision system 2 and the angular rate sensor 3 or the stabilized platform 4 on which the optronic vision system 2 and the angular rate sensor 3 are arranged are adjusted.

The image processing means 6 receive as input signal the image signals v_s 30 detected by the imaging sensor 2a. The image processing means 6 are designed configured to determine the present drift of the angular rate sensor 3 from or depending on a global movement of the scene recorded by the imaging sensor 2a within a predefinable or variable time interval. The image processing means 6 yield as output signal a signal which characterizes the global movement of the scene recorded by the imaging sensor 2a (in pixels/s) and which is provided with the reference sign b_s in Figure 1. The carrier system 1 is designed configured to convert the determined global movement b_s of the scene recorded by the imaging sensor 2a, preferably by means of a field of view resolution A, into an angular movement of the imaging sensor 2a (in rad/s). The signal characterizing the angular movement of the imaging sensor 2a is provided with the reference sign w_s in Figure 1 and is in turn fed as input signal to a drift controller unit 7. The drift controller unit 7 is designed configured to form a drift compensation signal d_s (in rad/s) from the signal b_s of the global movement of the scene recorded by the imaging sensor 2a and/or from the signal w_s of the angular movement of the imaging sensor 2a.

As is evident from Figure 1, the drive means 5a can stabilize the stabilized platform 4 or the optronic vision system 2 and the angular rate sensor 3 in an adjusting direction or axis indicated by the double-headed arrow Pl. However, the principle can equally be used for a two-and three-axis stabilization. The line of sight LOS of the optronic vision system 2 or of the imaging sensor 2a is stabilized by the adjusting of the optronic vision system 2.

The drift of the angular rate sensor 3 that is contained in the measurement signals m_s of the angular rate sensor 3 is corrected and/or compensated for by means of the drift compensation signal d_s of the drift controller unit 7 before the measurement signals m_s of the angular rate sensor 3 are fed to the stabilization means 5. For this purpose, the drift compensation signal d_s is added to the measurement signals m_s of the angular rate sensor 3 in a suitable manner, whereupon these drift-corrected measurement signals mb_s of the angular rate sensor 3 are fed as input signal to the stabilization controller unit 5b of the stabilization means 5. The drift-corrected measurement signals mb_s of the angular rate sensor 3 are thus corrected by elimination of the drift of the angular rate sensor 3. The drift controller unit 7 is designed configured to track the drift compensation signal d_s, in particular with a large time constant.

Figure 2 clarifies a global image movement or a drift vector in an image detected by an imaging sensor by means of arrows P2. In contrast thereto, Figure 3 indicates a small locally moved region L in a differential image.

The image processing means 6 can be designed configured, for the purpose of determining the global movement b_s of the scene recorded by the imaging sensor 2a, to use at least two images detected by the imaging sensor 2a in a time interval, in particular of 0.01 second to 1 hour, preferably of 1 second to 60 seconds.

For this purpose, the calculation of the global movement or of the global drift can be carried out, for instance, by means of a method for determining a sensor self-movement as disclosed in EP 1 441 316 A2. A consideration temporally further apart can be used in the present case. At least two images of the imaging sensor 2a in a time interval of 0.01 second to 1 hour, preferably of 1 second to 60 seconds, can be used for this purpose. The at least two images can then be subjected to low-pass filtering and be converted into the frequency domain by means of a Fast Fourier Transform (FFT). They can be convolved there, which corresponds to a correlation in the spatial domain, and the result can be transformed back into the spatial domain again by means of a reverse FFT. In the result image that arises therefrom, the results of all the correlations are indicated as grey-scale values. The position of the brightest grey-scale value in the result image accordingly corresponds to the shift of the second image relative to the first image of the imaging sensor 2a and thus to the drift of the stabilization system or of the angular rate sensor 3 in the time period between the two recordings (see Figure 2).

The determined global movement b_s of the scene recorded by the imaging sensor 2a can be checked for plausibility, in particular using a differential image.

In the case of extreme movements in the scene, incorrect calculations of the drift vector can possibly occur. It is thus advantageous to identify such incorrect calculations and then not to use them for stabilization or for compensation of the drift.

This can be carried out, e.g., by means of a locally tolerant subtraction in a so-called nine-cell neighbourhood of both images with a detection threshold taking account of the drift vector determined. In the case of correct calculation and little movement, markings can hardly be found in a differential image created in this way. If a large part of the differential image is marked as difference, then the calculation has failed and the result should therefore not be used, in which case a new calculation should be carried out. In the case of local regions having differences, a movement took place in the scene (see Figure 3). Starting from a limit value that can be set, e.g., between approximately 5% and approximately 50%, of the proportion of this local movement in the image, either this calculation, too, can no longer be used or the calculation must be carried out again with these regions being masked out. Since the drift compensation is carried out at relatively long time intervals and, therefore, is nowhere near being subject to video real-time requirements, such iterative or repeated calculations can be carried out without problems in the event of errors.

Alternatively or additionally, the image processing means 6 can be designed configured, for the purpose of determining the global movement b_s of the scene recorded by the imaging sensor 2a, to determine at least one static region in an image detected by the imaging sensor 2a, which is subsequently tracked by means of an object tracking.

In this case, an identified static region in the scene can be transferred to an object tracking of the image processing means 6. Methods for object tracking are sufficiently known from the prior art. Said object tracking can then track the position of a previously identified and automatically learned static region in the scene and forward the position changes identified in this case, preferably after having been subjected to temporal low-pass filtering, to the drift controller unit for compensation. In this way, the global movement and thus the present drift of the angular rate sensor 3 can be determined using simple means.

Consequently, a method for determining the drift of the angular rate sensor 3 is specified, wherein: - the imaging sensor 2a or at least the line of sight LOS thereof is stabilized with regard to position and/or alignment depending on the measurement signals m_s of the angular rate sensor 3, and wherein - in the image signals v_s of the imaging sensor 2a, at least one global movement 5 b s of the scene recorded by the imaging sensor 2a is detected within a predefinable time interval, from which the drift of the angular rate sensor 3 is determined.

Furthermore, a method for continuously stabilizing the position and/or the alignment of the optronic vision system 2 by means of the stabilization means 5 on the basis of to measurement signals m_s obtained by the angular rate sensor 3 is provided, wherein the drift of the angular rate sensor 3 is continuously determined by means of the above-specified method for determining the drift of the angular rate sensor 3, and whereupon, if the drift is present, the latter is at least approximately or completely corrected and/or compensated for, in particular using the stabilization means 5.

Figure 4 shows an embodiment of a movable carrier system 1 according to the invention comprising an optronic vision system 2 stabilized in two axes EL (elevation) and AZ (azimuth) and embodied as a sensor head. The fixing device 10a embodied as a fixing flange connects the optronic vision system 2 or the carrier system 1 to the carrier 10b. An adjustability of the optronic vision system 2 as position-stabilized component with respect to the axes EL and AZ is indicated by double-headed arrows P3a and P4a. Movements of the carrier 10b relative to the axes EL and AZ, said movements being indicated by double-headed arrows P3b and P4b, can thereby be correspondingly compensated for by the position stabilization. Translational directions are symbolized by the double-headed arrows P5. The optronic vision system 2 comprises an imaging sensor 2a, embodied as a camera, and a further imaging sensor 2b, embodied as a thermal imaging device. An angular rate sensor 3 which supplies measurement signals in both axes EL, AZ, is integrated in the optronic vision system 2 (indicated by dashed lines). Furthermore, provision is made of first drive means 5a.1 for adjusting the optronic vision system 2 along the axis EL and second drive means 5a.2 for adjusting the optronic vision system 2 along the axis AZ. It goes without saying that the optronic vision system 2 or the carrier system 1 in accordance with Figure 4 can also comprise the components 5b, 6 and 7 (indicated by dashed lines). For the purpose of determining the drift, in principle both imaging sensors 2a and 2b can be used either individually or in combination.

List of reference signs: 1 carrier system 2 optronic vision system 2a,2b imaging sensors 3 angular rate sensor 4 stabilized platform stabilization means 5a,5a.1, 5a.2 drive means 5b stabilization controller unit 6 image processing means 7 drift controller unit 10a fixing device 10b carrier LOS Line of Sight

A field of view resolution

L locally moved region EL elevation axis AZ azimuth axis m_s measurement signals of the position sensor mb_s drift-corrected measurement signals of the position sensor v_s image signals of the imaging sensor b_s signal regarding the global movement of the scene w_s signal regarding the angular movement of the imaging sensor d s drift compensation signal P1,P2,P3a, P3b,P4a, P4b,P5 arrows/double-headed arrows

Claims

Patent Claims: 1. Carrier system (1), at least comprising: - a position-stabilized component (2); -an imaging sensor (2a,2b), which is designed configured to continuously detect image signals of a region surrounding the carrier system (1); - a position sensor (3); - stabilization means (5) for continuously stabilizing the position and/or the alignment of the component (2) and the imaging sensor (2a,2b) or at least the line of sight 10 (LOS) thereof depending on measurement signals (m_s) of the position sensor (3); and - image processing means (6), which are designed configured to automatically determine a present drift of the position sensor (3) from the image signals (v_s) detected by the imaging sensor (2a,2b), wherein -the carrier system (1) is designed configured to automatically at least approximately correct and/or compensate for the present drift of the position sensor (3) determined by the image processing means (6), in particular by means of the stabilization means (5).
2. Carrier system (1) according to Claim 1, wherein the image processing means (6) are designed configured to determine the present drift of the position sensor (3) from a global movement (b_s) of the scene recorded by the imaging sensor (2a,2b) within a predefinable or variable time interval.
3. Carrier system (1) according to Claim 2, which is designed configured to convert the global movement (b_s) of the scene recorded by the imaging sensor (2a,2b) into an angular movement (w_s) of the imaging sensor (2a,2b).
4. Carrier system (1) according to Claim 2 or 3, wherein a drift controller unit (7) is 30 present, which is designed configured to form a drift compensation signal (d_s) from the global movement (b_s) of the scene recorded by the imaging sensor (2a,2b) or from the angular movement (w_s) of the imaging sensor (2a,2b).
5. Carrier system (1) according to Claim 4, which is designed configured to correct and/or compensate for the drift of the position sensor (3) contained in the measurement signals (m_s) of the position sensor (3) by means of the drift compensation signal (d_s) of the drift controller unit (7) before the measurement signals (m_s) of the position sensor (3) are fed to the stabilization means (5).
6. Carrier system (1) according to Claim 4 or 5, wherein the drift controller unit (7) is designed configured to track the drift compensation signal (d_s), in particular with a 10 large time constant.
7. Carrier system (1) according to any of Claims 2 to 6, wherein the image processing means (6) are designed configured, for the purpose of determining the global movement (b_s) of the scene recorded by the imaging sensor (2a,2b), to determine at least one static region in an image detected by the imaging sensor (2a,2b), which is subsequently tracked by means of an object tracking.
8. Carrier system (1) according to any of Claims 2 to 7, wherein the image processing means (6) are designed configured, for the purpose of determining the global movement (b_s) of the scene recorded by the imaging sensor (2a,2b), to use at least two images detected by the imaging sensor (2a,2b) in a time interval, in particular of 0.01 second to 1 hour, preferably of 1 second to 60 seconds.
9. Carrier system (1) according to any of Claims 1 to 8, wherein the stabilization 25 means (5) comprise: - drive means (5a,5a.1,5a.2) in order to carry out a movement of the position-stabilized component (2); and - a stabilization controller unit (5b), which is communication-connected to the drive means (5a,5a.1,5a.2) and the position sensor (3) and which receives the measurement signals (m_s) of the position sensor (3) as input signals and which is designed configured to control an inertial rotational movement present in the measurement signals (m_s) of the position sensor (3) to zero by driving the drive means (5a,5a.1,5a.2) in such a way that the position-stabilized component (2) and the position sensor (3) are adjusted.
10. Carrier system (1) according to any of Claims 1 to 9, wherein the position sensor 5 is embodied as an angular position sensor or angular rate sensor (3).
11. Carrier system (1) according to any of Claims 1 to 10, wherein the position-stabilized component (2) comprises the imaging sensor (2a,2b) or an element which stabilizes the line of sight of the imaging sensor (2a,2b).
12. Carrier system (1) according to any of Claims 1 to 11, wherein the position-stabilized component is an optronic vision system (2).
13. Method for determining a drift of a position sensor (3), wherein: -at least one imaging sensor (2a,2b) or at least the line of sight (LOS) thereof is stabilized with regard to position and/or alignment depending on measurement signals (m_s) of the position sensor (3), and wherein - in image signals (v_s) of the at least one imaging sensor (2a,2b), at least one global movement (b_s) of the scene recorded by the at least one imaging sensor (2a) is 20 detected within a predefinable time interval, from which the drift of the position sensor (3) is determined.
14. Method according to Claim 13, wherein the global movement (b_s) of the scene recorded by the imaging sensor (2a,2b) is converted into an angular movement (w_s) 25 of the imaging sensor (2a,2b).
15. Method according to Claim 13 or 14, wherein for the purpose of determining the global movement (b_s) of the scene recorded by the imaging sensor (2a,2b): - at least two images detected by the imaging sensor (2a,2b) in a time interval, in 30 particular of 0.01 second to 1 hour, preferably of 1 second to 60 seconds, are used; and/or - at least one static region is determined in an image detected by the imaging sensor (2a,2b), which is subsequently tracked by means of an object tracking.
16. Method according to Claim 13, 14 or 15, wherein the determined global movement (b_s) of the scene recorded by the imaging sensor (2a,2b) is checked for plausibility, in particular using a differential image.
17. Method for continuously stabilizing the position and/or the alignment of a component (2) by means of stabilization means (5) on the basis of measurement signals (m_s) obtained by a position sensor (3), wherein a drift of the position sensor to (3) is determined continuously by means of a method according to any of Claims 13 to 16, and whereupon, if the drift of the position sensor (3) is present, the latter is at least approximately corrected and/or compensated for, in particular using the stabilization means (5).
18. Method according to Claim 17, wherein a drift compensation signal (d_s) is formed from the global movement (b_s) of the scene recorded by the imaging sensor (2a,2b) or from the angular movement (w_s) of the imaging sensor (2a,2b).
19. Method according to Claim 17 or 18, wherein the drift of the position sensor (3) contained in the measurement signals (m_s) of the position sensor (3) is corrected and/or compensated for by means of the drift compensation signal (d_s) before the measurement signals (m_s) of the position sensor (3) are fed to the stabilization means (5).
20. Method according to Claim 18 or 19, wherein the drift compensation signal (d_s) is tracked adjusted in particular with a large time constant.
21. Method according to any of Claims 13 to 20, wherein an angular position sensor or an angular rate sensor (3) is used as the position sensor.
22. Method according to any of Claims 13 to 21, wherein the position-stabilized component (2) comprises the imaging sensor (2a,2b) or an element which stabilizes the line of sight of the imaging sensor (2a,2b).
23. Method according to any of Claims 13 to 22, wherein an optronic vision system (2) is used as the position-stabilized component.