DE102009050522B4 - Localization system and method for finding thermals - Google Patents

Abstract

Localization system (1) for finding local thermal areas, which has at least the following components:
An infrared camera (2);
- An IR image processing unit (3) connected to the infrared camera (2); and
A motion prediction unit (6);
characterized in that
the movement prediction unit (6) has a receiving unit for corresponding weather data or a storage unit with stored weather data for deriving a simplified motion model of the thermal and wherein the localization system (1) further comprises an evaluation unit (7) for determining the position of a locally occurring thermal area in a three-dimensional coordinate system is connected to the IR image processing unit (3) and to the motion prediction unit (6).

Description

The invention relates to a localization system and a method for locating locally occurring thermals, such as those used by aircraft such as gliders to increase the altitude by the thermal windings and thus to influence the flight path or flight time.

One reason for the occurrence of thermals lies in the different degrees of warming of the soil depending on fouling, orientation, soil conditions and moisture. For example, dry, less vegetated areas with sandy soil heat up faster than forest or water areas or wet pastureland. The faster warming also leads to a faster and stronger warming of the air layers immediately above these areas. Warmer air increases when the surrounding air layers have a lower temperature. The rise of such warm air layers occurs in particular when external influences such as wind, the near-ground warm air to so-called "demolition edges", d. H. Obstacles such. As forest edges, mountain slopes, roads, etc., presses and thereby for "detachment" from the ground forces.

In sport aviation, especially in gliding, it is common to make use of areas with rising due to temperature differences air masses, so-called thermal. Aircraft located within such areas can maintain or extend their altitude without power and even travel longer distances without or with reduced energy consumption. In particular, in reconnaissance and observation missions of unmanned aerial vehicles (UAVs) there are considerable degrees of freedom in the selection of the local trajectories, which allow for extension of the duration of flight by taking into account localized thermal.

Several solutions for locating locally occurring thermals are already known from the prior art. Thus, the German patent publication DE 435004 a device to make perceptible on gliders the change of the wind flow, as it occurs when approaching thermal areas, by a sound changing with it. It is in accordance with the DE-PS 435004 to expose the windstream to a siren that changes its velocity and thus its sound as the wind flow changes. In this case, the perception of the change in tone on an electric-acoustic way to be done by means of microphones. Disadvantage of this prior art is that you have to be here already very close to the updraft to receive appropriate signals.

A similar approach to the solution proposed above pursues the DE 4035311 C1 , This document describes a method and a device for finding gliders for gliders. According to this prior art, the infrared radiation emanating from thermal Aufwindfeldern is detected with an electro-acoustic transducer. The frequency band from 3 Hz to 16 Hz is filtered out, amplified and fed to a frequency / voltage converter. The highest received frequency is then displayed. In addition, the device includes a measuring device for the relative signal strength of the received signal and an acoustic display proportional to the frequency of the signal. Again, you have to be relatively close to the thermal area to receive appropriate signals. For more distant thermal areas noise and the drift of sound due to horizontal air currents make it difficult to locate the thermal area.

The DE-OS 2248466 discloses a glider thermal sensor which measures the temperature change of the ambient air that is disregarded by the variometer. This is done by approximately determining the components of the temperature gradient in the direction of the aircraft transverse axis and the aircraft's longitudinal axis. These two components combine to form a two-dimensional vector that points in the direction of the largest increase in temperature and thus the strongest upwind. To measure the two gradient components, temperature sensors are used on the two wings at a distance of a span of normally 15 m. The transverse component of the temperature change is now proportional to the temperature difference at the two sensors. To measure the longitudinal component, two additional temperature sensors can now be used in the same way in the front and rear of the fuselage. These can be saved, however, because due to the forward movement of the aircraft, the time change of the average value of the temperatures at the two temperature sensors on the wings is proportional to the longitudinal component of the temperature gradient. Even with this solution, thermal areas in the greater distance are very difficult to detect.

Furthermore, a number of centering aids for aircraft are still known, which use the updraft by circles for height extraction. It should be achieved that the pilot as possible revolves around the center of the updraft channel and thus an optimum height gain is achieved. Such solutions are based either on the evaluation of Variometermessungen or mechanical changes in forces on the wings and are for example from the DE 19731081 A1 , of the DE 9017565 U1 and the WO 83/01050 A1 known. Again, the aircraft must already be in the immediate vicinity or already in the thermal area.

Finally, out of the DE 41 34 633 A1 a locating device for thermal updraft areas is known, which should allow a approach of such thermal areas directly. In this case, a solution is proposed as the solution, which scans the air space with a special suitable for the long-wave infrared region pyroelectric sensor according to the principle of passive infrared detection. The scanning is carried out by a horizontal pivoting movement of the sensor and allows the finding of temperature differences between the warmer Aufwindgebieten and the slightly colder ambient air, ie thus operates on the basic principle of DE-OS 2248466 , but with the advantage that the upwind areas can be found at greater distances. The approach to a corresponding thermal area is according to the DE 41 34 633 A1 indicated by two diodes and complemented by an acoustic signal in the immediate approach. The infrared radiation to be located is accordingly in the range of 50 μm. Disadvantage of this solution is that the distance to the updraft region can be determined only at a significant approximation. Also hereby no statement can be made whether larger or more favorable for the flight route Aufwindgebiete are available. The pure diode display is also no position determination, for example, for mapping geographic conditions where thermal often occurs, possible.

Furthermore, from the US Pat. No. 6,828,934 B2 an airborne microwave / infrared wind shear and air hole detector known. For this purpose, the air in front of the aircraft is heated by direct high-energy radiation such as microwave radiation from a respective microwave antenna and converted into images by means of an infrared camera. By monitoring these generated images, the presence of an airborne fault can be detected. The high energy beams preferably maintain a predetermined distance in front of the aircraft so that an evasive maneuver can be performed. For this purpose, an evaluation unit with a movement prediction unit and the movement prediction unit are in turn connected to an air speed meter. The airspeed meter provides the motion prediction unit with information, such as the airspeed of the aircraft. Thus, the high-energy beams are positioned by position adjuster.

Last is still out of the US Pat. No. 7,515,088 B1 a weather radar detection system and method adaptively known for weather characteristics. The method includes determining a classification of the weather and automatically adjusting the weather radar system in response to the classification of the weather. The invention is therefore based on the object to avoid the disadvantages of the known solutions of the prior art and to provide an improved solution for finding locally occurring thermals at a great distance. In addition, a comparison of several local thermal areas to be possible by the invention, which can be selected depending on preference, the largest, the nearest or lying on the predetermined course local thermal area.

This object is achieved by a localization system for finding local thermal areas with the features of claim 1 and a method for finding local thermal areas with the features of claim 7. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

As a result, the disadvantages of the known solutions of the prior art are avoided and provided an improved solution for finding locally occurring thermals at a great distance. In addition, a comparison of several local thermal areas is possible by the invention, which can be selected depending on preference, the largest, the nearest or lying on the given course local thermal area.

The occurrence of thermals can have different reasons. The movement of thermal detachments from heated floor surfaces depends on influences such as the orientation of the spoiler edge, the size of the heated floor surface, the wind directions, wind speeds and the temperature gradient in the course of the altitude and the overall weather situation. From a few known influencing variables, such as the vertical wind directions and the temperature profile, which are routinely predicted and / or measured with great accuracy by modern meteorology, it is possible with a movement prediction unit, for example a CPU with receiving unit for corresponding weather data or a storage unit with stored weather data , which can be entered before the aircraft is launched, derive a simplified model of movement of the thermals. By the evaluation unit then takes place a position determination of a locally occurring thermal area in a three-dimensional coordinate system based on the vertical wind directions and - wind speeds, the temperature profile and by means of the infrared camera and IR-associated image processing unit identified floor areas with increased heat radiation and their also identified demolition edges.

The invention also allows the detection of thermal at night. Areas of low heat radiation but high heat storage capacity, such as water or forest areas, radiate absorbed heat after sunset. These areas and possible demolition edges can be identified in infrared image data with the localization system according to the invention and the method according to the invention also at night. Finally, depending on the size of the aircraft and the accuracy of the measurement method, the invention can also be used in general aviation for determining turbulences caused by ground-level thermal z. B. at take-off or landing approach, as well as for the discovery of cloud thermics are used.

A particularly advantageous embodiment of the invention provides automatic image processing on the basis of optical and infrared camera image data. Thus, possible causes for the occurrence of thermals can be identified in an automatic form by means of image processing of optical and infrared camera image data, the development of thermals in consideration of meteorological conditions predicted and by localization of the thermals in a suitable coordinate system or appropriate visual representation for the flight planning of Aircraft can be harnessed.

Advantageously, an optical and an infrared camera can be mounted on an aircraft and measured or calibrated relative to the aircraft and relative to each other. The infrared camera can be calibrated to improve the measurement accuracy such that color values in the image can be assigned to specific temperatures.

In the acquired infrared image data, floor areas with higher heat radiation can be automatically detected by lighter colors. The coloring allows conclusions about the temperature of the area. By means of a search over all points in the infrared image, such bright colors can be automatically identified and, given a known position of the infrared camera, assigned to the corresponding floor areas and their coordinates in a common coordinate system and the corresponding surfaces registered one another.

In optical image data, possible demolition edges can be determined on the basis of strong locally occurring color differences, ie. H. automatically identified by color gradients and associated with the known position of the optical camera the corresponding floor areas and their coordinates in a common coordinate system and the corresponding edges are registered to each other.

With known wind directions and temperature curves, the movement of the thermals at the automatically identified points can now be calculated and projected into a three-dimensional coordinate system known to the aircraft. An optionally available navigation system can now incorporate the areas of possible occurrence of thermals in the flight planning and keep the altitude by circular or stationary flight in these areas with reduced engine power or increase and thereby increase the overall flight time.

For checking or confirming the presence of thermals in the areas determined by the method described above, it is possible to use the sensors commonly used in aircraft, for example a variometer, inertial sensors, etc. When flying through the identified, thermally active areas at constant flight direction and speed occurs in the presence of thermal positive vertical acceleration of the aircraft and can be measured with the sensor. Based on the extent of the areas with measured vertical accelerations, a fine localization of the most thermally active areas can then take place. The vertical accelerations actually measured by means of the sensor system of the aircraft in the calculated ranges of local thermals can be used to dynamically refine the thermal model on which the calculation is based, or the underlying parameters, such as, for example, B. the wind directions to adapt dynamically. Furthermore, thermals measured by the aircraft's sensor system, but not predicted by the existing thermal model, can be used by standard approaches of statistical learning to identify the most likely causes of thermals in the image data and extend the calculation model used to these new causes.

In addition, navigation systems of aircraft, in particular unmanned aerial vehicles (UAVs), can specifically take into account the local thermal areas discovered in the flight planning or trajectory planning and thereby extend the duration of flight and improve energy efficiency. In the case of unmanned aerial vehicles (UAVs), which are increasingly being used in the civilian and military sectors to perform surveillance and reconnaissance tasks, trajectory planning can, for example, be completely autonomous. The duration of flight of UAVs is essential for practical use in missions.

Finally, several aircraft, in particular several unmanned aerial vehicles, but at the same time independently depart from an area and identify thermally active areas by means of the invention and then make each other the data on the strongest thermal areas each other, for example by radio transmission available. As a result, the area covered by the thermal search can be considerably expanded.

Further measures improving the invention will be described in more detail below together with the description of a preferred embodiment of the invention with reference to FIGS. Show it:

1 a schematic representation of an advantageous embodiment of a localization system for finding local thermal areas;

2 a schematic representation of the movement of thermals due to the course of the wind directions, wind speeds and temperatures at different heights;

3 an infrared aerial view, where lighter colors correspond to higher surface areas;

4 an aerial aerial view of the area 3 ;

5 a result of an automatic edge detection of possible demolition edges in 4 ;

6 a localization of in the infrared image 3 Found heated bottom surfaces along possible edges 5 in the appropriate direction to the wind in a common coordinate system 4 ;

7 a three-dimensional localization of thermals in the course of altitude with known weather data (wind directions, temperatures) for further processing by a navigation system;

8th a schematic flow chart with the input variables infrared image, optical image, wind profile in the altitude profile, the processing steps color area extraction and edge detection, and the output variables thermal localization and trajectory planning.

1 shows a schematic representation of an advantageous embodiment of a localization system 1 to find local thermal areas with an infrared camera 2 , an IR image processing unit 3 as well as an optical camera 4 and an optical image processing unit 5 , The two image processing units 3 and 5 are with an evaluation unit 7 which, in turn, provides weather data from a motion prediction unit 6 receives. With this data and the cartographic data of a navigation system 8th determines the evaluation unit 7 The location of local thermal areas and displays them in a three-dimensional coordinate system on the input / output unit 9 at. About the navigation system 8th then a trajectory planning can be done.

According to the advantageous embodiment of the invention, the optical camera 4 and the infrared camera 2 mounted on a (not shown) aircraft and measured relative to the aircraft and relative to each other or calibrated. The infrared camera 2 can be calibrated to improve the measurement accuracy such that color values in the image can be assigned to specific temperatures. The localization in a three-dimensional coordinate system as well as the measurement of the camera positions can also be carried out by automatically determining escape and horizon lines in the camera images if the cameras are not known to be calibrated.

2 FIG. 12 shows a schematic representation of the movement of thermals due to the course of the wind directions and temperatures at different altitudes, as determined by the movement prediction unit based on meteorological forecasts for the geographical area in the movement prediction unit 6 stored and processed.

In the from the infrared camera 2 obtained infrared image data can by means of the IR image processing unit 3 Floor areas with higher heat radiation are automatically detected by lighter colors, as in 3 shown schematically in gray scale. The coloring allows conclusions about the temperature of the area. By searching over all points in the infrared image, such bright colors can be automatically identified and, if the position of the infrared camera is known 2 be assigned by calibration to the corresponding floor areas and their coordinates in a common coordinate system and the corresponding surfaces are registered to each other.

According to 4 can by means of the optical image processing unit 5 in the optical image data possible demolition edges based on strong locally occurring color differences, ie on the basis of color gradients, automatically identified and marked accordingly, as in 5 shown with thick lines. With known position of the optical camera 4 can then be assigned to the corresponding floor areas and their coordinates in a common coordinate system, the corresponding demolition edges and registered to each other, as in 6 shown.

At out of the motion prediction unit 6 known wind directions and temperature curves can now the movement of the thermals at the automatically identified points in an evaluation unit 7 calculated and in a the navigation system 8th the aircraft known three-dimensional coordinate system are projected, as in 7 shown. In 7 Several thermal areas are visible at different distances and different sizes.

The optionally available navigation system 8th of the aircraft can now incorporate the areas of possible occurrence of thermals in the flight planning and keep or increase altitude by circular or stationary flight in these areas with reduced engine power and thereby increase the overall flight time. The procedure of the whole procedure is schematically in 8th summarized.

LIST OF REFERENCE NUMBERS

1

Localization system for finding local thermal areas

2

Infrared camera

3

IR image processing unit

4

Optical camera

5

Optical image processing unit

6

Motion prediction unit

7

evaluation unit

8th

navigation system

9

Input / output unit

Claims (14)

Localization system ( 1 ) for locating local thermal areas, which comprises at least the following components: - an infrared camera ( 2 ); - one with the infrared camera ( 2 ) IR image processing unit ( 3 ); and - a motion prediction unit ( 6 ); characterized in that the movement prediction unit ( 6 ) has a receiving unit for corresponding weather data or a storage unit with stored weather data for deriving a simplified movement model of the thermal and wherein the location system ( 1 ) an evaluation unit ( 7 ), which for determining the position of a locally occurring thermal region in a three-dimensional coordinate system with the IR image processing unit ( 3 ) and with the movement prediction unit ( 6 ) connected is. Localization system ( 1 ) for locating local thermal areas according to claim 1, wherein further at least the following components are provided: - an optical camera ( 4 ); - one with the optical camera ( 4 ) connected optical image processing unit ( 5 ); wherein the evaluation unit ( 7 ) with the optical image processing unit ( 5 ) connected is. Localization system ( 1 ) for locating local thermal areas according to claim 1 or 2, wherein the locating system is arranged on an aircraft. Localization system ( 1 ) for locating local thermal areas according to claim 2 or 3, wherein the position and orientation of the infrared camera ( 2 ) and the optical camera ( 4 ) are arranged calibrated relative to each other. Localization system ( 1 ) for finding local thermal areas according to one of the preceding claims, wherein the location system ( 1 ) at least one electronic navigation system ( 8th ) having. Localization system ( 1 ) for finding local thermal areas according to one of the preceding claims, wherein the location system ( 1 ) further comprises at least one trajectory planning unit. A method for finding local thermal areas, comprising the following steps: - storing current altitude wind directions and wind speeds and the temperature profile for a geographical area in a movement prediction unit; - acquiring an infrared image of a geographical area with an infrared camera; - finding ground surfaces with increased heat radiation with an IR image processing unit connected to the infrared camera; - Position determination of a locally occurring thermal area in a three-dimensional coordinate system by an evaluation unit based on the vertical wind directions and wind speeds, the temperature profile and floor areas with increased heat radiation. Method for locating local thermal areas according to claim 7, wherein further demolition edges of thermal areas are detected by locally occurring color differences with an optical camera and automatically evaluated by an optical image processing unit, wherein the evaluation unit is connected to the optical image processing unit and these data in the position determination of a local occurring thermal area considered. Method for finding local thermal areas according to claim 7 or 8, wherein the infrared camera and the optical camera are calibrated relative to each other, or an automatic determination of escape and horizon lines in the camera images done. A method of finding local thermal areas according to any one of claims 7-9, wherein the orientation of the identified floor area is determined with increased heat radiation relative to the sun's position and the result is included in the calculation of the thermal activity. A method for locating local thermal areas according to any one of claims 7-10, wherein the coordinates of the detected local thermal areas are registered in a map and stored on a data memory, and when approaching the geographical area these coordinates as the starting coordinates for a re-determination of local thermal areas be used. Use of a localization system for locating local thermal areas according to any one of claims 1-6 in an unmanned aerial vehicle. Use according to claim 12, wherein the unmanned aerial vehicle autonomously integrates the local thermal areas located with the localization system into the trajectory planning. Use according to claim 12 in a plurality of simultaneously flying unmanned aerial vehicles which make their data mutually available to found local thermal areas.

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