Passive target data acquisition method and system
Abstract
A method that uses a passive objective data acquisition system (PTAS) (18) operating from an observation point (56) for the passive display of a target (58, 86, T), having the PTAS: passive observation means coupled to a navigation device (44) and azimuth angle (alpha) and elevation (delta) measuring devices, a computer module (20) functionally coupled to a database from DTM (22), to the observation means, and to a screen (30), the method comprising the steps of: measure the location data of the observation point and the azimuth angle and elevation data to the target, provide the measured data to the computer module, guide a vector (54, 70, v) towards the target, run a PTAS computer program on the computer module to calculate the point of intersection of the vector with the surface of the DTM and present both the observation point and the target on a corresponding DTM surface deduced from the base on the screen of DTM data, through which passive data are acquired passively to avoid the emission of radiation characterized in that it comprises the steps of: define an environment that surrounds the vector that originates at the observation point and a wrap mantle distanced from the vector proportionally to the measurement errors, run the PTAS computer program to calculate the points of intersection of the envelope with the surface of the DTM, and present the intersection points, an area of uncertainty defined by the intersection points, and the associated information on the screen.

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23 claims: 2 independent, 21 dependent
- 1ES 2 312 971 T3 REIVINDICACIONES 1. Un método que usa un sistema de adquisición pasiva de datos de objetivo (PTAS) (18) operativo desde un punto de observación (56) para la visualización pasiva de un objetivo (58, 86, T), teniendo el PTAS:medios de observación pasiva acoplados a un dispositivo de navegación (44) y a dispositivos (48, 46) de medición del ángulo de azimut (a) y de elevación (δ), un módulo de ordenador (20) acoplado funcionalmente a una base de datos de DTM (22), a los medios de observación, y a una pantalla (30), comprendiendo el método las etapas de: medir los datos de localización del punto de observación y los datos del ángulo de azimut y de elevación al objetivo, suministrar los datos medidos al módulo de ordenador, guiar un vector (54, 70, v) hacia el objetivo, ejecutar un programa de ordenador de PTAS sobre el módulo de ordenador para calcular el punto de intersección del vector con la superficie del DTM y presentar sobre la pantalla tanto el punto de observación como el objetivo sobre una superficie del DTM correspondiente deducida a partir de la base de datos del DTM, por medio del que se adquieren pasivamente los datos del objetivo para evitar la emisión de radiaciones caracterizado porque comprende las etapas de: definir un entorno que rodea al vector que se origina en el punto de observación y un manto de envoltura distanciado desde el vector proporcionalmente a los errores de medición, ejecutar el programa de ordenador del PTAS para calcular los puntos de intersección de la envoltura con la superficie del DTM, y presentar los puntos de intersección, un área de incertidumbre definida por los puntos de intersección, y la información asociada sobre la pantalla.
- 2El método de acuerdo con la reivindicación 1, que incluye adicionalmente:ejecutar el programa de ordenador del PTAS para deducir la distancia de separación entre los puntos de intersección seleccionados sobre la superficie del DTM, y deducir una medición de alcance que separa el punto de observación del objetivo.
- 3El método de acuerdo con la reivindicación 1, que incluye:ejecutar el programa de ordenador del PTAS para deducir los datos del objetivo que comprenden del alcance del objetivo y la localización del objetivo.
- 4El método de acuerdo con la reivindicación 1, que incluye:el funcionamiento ininterrumpido para deducir continuamente los datos calculados y medidos, y el funcionamiento ininterrumpido para proporcionar continuamente el alcance del objetivo, los datos de localización del objetivo, y la información asociada.
- 5El método de acuerdo con la reivindicación 1, que incluye:detectar la existencia de zona(s) muerta(s) distribuidas a lo largo del vector, entre el punto de observación del objetivo, y trazar la(s) zona(s) muerta(s) sobre la pantalla. ES 2 312 971 T3
- 6El método de acuerdo con la reivindicación 1, que incluye:suministrar al programa de ordenador del PTAS los datos seleccionados que comprenden la localización de la oposición, longitud del vector de la LOS, ángulos de azimut y elevación y ejecutar el módulo de ordenador del PTAS de acuerdo con los datos seleccionados para visualizar la(s) zona(s) muerta(s) del terreno y la información asociada.
- 7El método de acuerdo con la reivindicación 1, que incluye:visualizar el objetivo desde un punto de observación situado por encima de la superficie del DTM y situado tanto en una plataforma transportada por aire como en una plataforma espacial o en ambas.
- 8El método de acuerdo con la reivindicación 1, que incluye:visualizar el objetivo desde un punto de observación situado tanto en una plataforma basada en tierra como en una plataforma marítima o en ambas.
- 9El método de acuerdo con la reivindicación 1, que incluye:fijar el PTAS sobre una plataforma estabilizada.
- 10El método de acuerdo con la reivindicación 1, en el que:los datos medidos y la información asociada están disponibles para su salida en formato digital, y los datos mostrados en la información asociada son recuperables desde la pantalla.
- 11El método de acuerdo con la reivindicación 1, para buscar rápidamente la dirección Norte con precisión, que incluye:obtener al menos una lectura de la dirección Norte aproximada para la introducción en el módulo de ordenador, caracterizado porque comprende las etapas de: ejecutar un programa ordenador del procedimiento de búsqueda del Norte (NFP) sobre el módulo de ordenador para determinar un sector de la zona de observación (234), dividiendo la zona de observación en sub-sectores (239) y definir los objetivos de referencia (X), usar un dispositivo de medición de alcance activo para medir activamente el alcance desde el punto de observación a al menos un objetivo de referencia, suministrar los datos de al menos un alcance medido activamente en el módulo de ordenador, y ejecutar el programa de ordenador del NFP para calcular la desviación en los datos de azimut en al menos un objetivo de referencia mediante la asociación respectiva del alcance como se calcula por el PTAS y el alcance como se mide activamente para derivar un factor de desviación de azimut común que proporciona un factor de corrección para la indicación del Norte con precisión.
- 12El método de acuerdo con la reivindicación 11, en el que dichos objetivos de referencia son al menos dos y donde dichas mediciones activas de alcance son al menos dos.
- 13El método de acuerdo con la reivindicación 12, que incluye:seleccionar aleatoriamente un objetivo de referencia en cada uno de los al menos dos sub-sectores no adyacentes.
- 14El método de acuerdo con la reivindicación 12, en el que la ejecución del programa de ordenador del NFP incluye:dividir la zona de observación automáticamente en sub-sectores, y ES 2 312 971 T3 definir un objetivo de referencia seleccionado como un lugar geométrico para el que cada pequeña desviación en el azimut del vector de observación encuentra un gran cambio en el alcance.
- 15El método de acuerdo con la reivindicación 12, que incluye:ejecutar el programa de ordenador del NFP para el cálculo de si los ajustes de la localización del punto de observación reduce el valor del factor de desviación común, y ajustar la localización del punto de observación cuando los ajustes calculados en consecuencia reducen el valor del factor de desviación común.
- 16El método de acuerdo con la reivindicación 1, para la búsqueda super rápida pasiva de la dirección Norte con precisión, que incluye:definir un objetivo avistado específico sobre el terreno que rodea el punto de observación y tomar una lectura de datos de azimut aproximada del mismo, medir la localización del punto de observación, y tanto los datos del ángulo de azimut como de elevación hacia el objetivo de visualización específico, y suministrar los datos medidos como datos de entrada al módulo de ordenador, comprendiendo el método las etapas de: ejecutar el programa de ordenador del PTAS para calcular con los datos de entrada y los resultados de visualización sobre la superficie del DTM como un objetivo aproximadamente calculado, encontrar el objetivo singular de visualización sobre la pantalla, y leer los datos del objetivo de visualización específico como un azimut preciso a partir de la superficie del DTM, y ajustar el azimut del objetivo calculado aproximadamente con el azimut preciso, que se alimenta en el módulo del ordenador, para deducir un factor de desviación de azimut que proporciona un factor de corrección para indicar el Norte con precisión.
- 17Un sistema de adquisición pasiva de datos de objetivo (PTAS) (18) posicionado y operativo en un punto de observación (56) para la visualización pasiva de un objetivo (58, 86, T), a lo largo de un vector LOS (54, 70, v), que incluye:medios de observación pasiva que comprenden un dispositivo de navegación (44) para medición de los datos de localización del punto de observación, dispositivos (48, 46) de medición del ángulo de azimut (a) y de elevación (δ) para medir los datos del ángulo de azimut y de elevación hacia el objetivo, un módulo de ordenador (20) acoplado funcionalmente a un módulo de DTM (22), a los medios de observación, y a una pantalla (30), módulo de ordenador que recibe las medidas de la localización del punto de observación y de los datos angulares del objetivo para presentación sobre la pantalla de una superficie del DTM correspondiente deducida a partir del módulo del DTM, por medio del que los datos del objetivo se adquieren pasivamente para evitar la emisión de radiaciones, caracterizado porque: un programa de ordenador de PTAS que se ejecuta sobre el módulo de ordenador para calcular el punto de intersección del vector y de una envoltura, que rodea radialmente la longitud del vector de la LOS que se origina en el punto de observación y que presenta un manto de envoltura que se distancia a partir del vector de la LOS proporcionalmente a los errores de medición, con la superficie del DTM, y presenta los puntos de intersección con la información asociada sobre la pantalla.
- 18El PTAS de acuerdo con la reivindicación 17, en el que:al menos un área de error del objetivo (90, 92) se muestra sobre la pantalla en asociación con el objetivo.
- 19El PTAS de acuerdo con la reivindicación 17, en el que:la información asociada procesada por el módulo de ordenador, comprende: un punto de navegación para el punto de observación y para el objetivo, y ES 2 312 971 T3 un alcance que indica la distancia desde el punto de observación al objetivo y al menos a un área de error del objetivo, y una salida de información asociada en formato digital configurado para transmisión y para presentación sobre la pantalla.
- 20El PTAS de acuerdo con la reivindicación 19, que incluye:una capacidad de detección de zona muerta proporcionada por el programa de ordenador del PTAS, para deducir la distancia de separación entre las áreas de error del objetivo, cuando se detectara más de al menos un área de error, y producir la información asociada con la zona muerta y el área de error en formato digital configurado para transmisión y para presentación de la zona muerta y de la información asociada del área de error sobre la pantalla.
- 21El PTAS de acuerdo con la reivindicación 17, que incluye:una configuración del sistema implementada como un agregado de módulos fácilmente disponibles integrados con módulos complementarios añadidos y los programas de ordenador adecuados.
- 22El PTAS de acuerdo con la reivindicación 17, que incluye:una plataforma para fijar funcionalmente el PTAS, seleccionándose la plataforma entre un grupo de plataformas estáticas y móviles que consisten en plataformas basadas en tierra, en el aire, el mar y en el espacio, e implementándose la plataforma seleccionada como una plataforma estabilizada o como no estabilizada o ambas.
- 23El PTAS de acuerdo con la reivindicación 17, en el que el módulo de ordenador comprende una lectura aproximada de la dirección Norte, incluyendo adicionalmente el PTAS:un programa de ordenador del procedimiento de búsqueda del Norte (NFP) que se ejecuta sobre el módulo de ordenador para determinar un sector de la zona de observación (234), dividida en sub-sectores (239) con referencia a los objetivos de referencia (X) definidos en ellos, un dispositivo de medición de alcance activo para medir activamente el alcance desde el punto de observación hasta al menos dos objetivos de referencia, el módulo de ordenador que es capaz para recibir al menos dos alcances medidos activamente, y el programa de ordenador del NFP que es capaz de calcular la desviación en los datos de azimut en al menos dos objetivos de referencia mediante la asociación respectiva del alcance como se calcula por el PTAS y el alcance como se mide activamente para derivar un factor de desviación de azimut común que proporciona una corrección más rápida para la indicación del Norte con precisión.
Independent claims23
119 paragraphs in 9 sections, as filed
ES 2 312 971 T3
DESCRIPTION
Procedure and system for passive acquisition of target data.
Technical field
The present invention relates generally to the field of the use of digital maps in navigation. More particularly, the present invention relates to a method and a system for the passive acquisition of data of a target in relation to a digital map, and even more, to the use of the method and the system to find the North direction accurately.
Previous technique
The visual means for acquiring data from a target are well known per se. These optical instruments are used by geodesists and gunners, for example. Such equipment is comparable to a theodolite or compass theodolite, with a rotating base for pointing a telescope at the target. Typically these include a compass, a computer with a CPU to run the computer programs, an input / output unit, a memory and a display device, or simply a display. The pitch and yaw angles from an observation point to a target are measured with a vernier. More often, an active range measurement device, such as an LRF, is also included.
It is taken for granted that all modern viewing devices include an optical device, for example a telescope or binoculars, and have to be powered and leveled before use. Optics, feeding, and leveling are standard and common practice in the art, and will therefore not be mentioned below in the description.
Also known in the art is the acronym DTM (digital terrain model), or DEM (digital elevation model) which refers to digitized topographic models that provide a representation of the contour of the surface of a part of the terrain in the form of a digital map in three dimensions. Parties that perform surface or volume calculations with respect to modeled terrain possibly make use of such a DTM. When the DTM is stored in the memory of a computer, it can be used as a unit in a terrain database. The stored DTM then provides the basic data for executing the area and volume calculations implemented by a computer program associated with a computer and computer memory. Various engineering, military and environmental applications frequently refer to the DTM for surface or spatial calculations. A graphical illustration of a DTM is given in Figure 1, to which reference is now made.
Figure 1 shows a DTM surface S derived from a DTM database, associated with a Cartesian coordinate system (x, y, z), having a grid plane of points with coordinates (x, y) in the xy plane. A height (z) coordinate is defined for each discrete pair of (x, y) coordinates. Each point sampled on the contour of the terrain surface is represented by a junction of the X and Y lines on the grid. The height of each sampled point is given by values along the Z axis. The resolution of the DTM sample points in the X - Y plane, and the precision of the height measurements of each sampled point depend on various factors, for example, of the quality of the aerial photography from which the map has been prepared.
In US Patent No. 5,086,396, Waruszewsky Jr. describes "an aircraft navigation system" that includes "an inertial navigation system, a map of the terrain with elevation information stored in digital format as a function of the localization, a typical power management of a narrow beam altimeter (radar or laser), a display system, and a central processing unit for data processing according to preselected programs ”. This is an example of using a DTM for navigation purposes. Waruszewsky Jr. further explains that “the correct position of the aircraft with respect to the digitized map can allow the aircraft to enter into ground tracking procedures that use only devices to find the range in the flight position difficult to detect as a source of radiation electromagnetic emitted ”. Here Waruszewsky Jr. refers to the problems associated with detecting active detectors.
In US Patent No. 6,222,464, Tinkel et al. disclose “An automated method of scanning compensation in a target acquisition system to reduce potential risk areas surrounding an aircraft. The target acquisition system includes a scanning device with adjustable scanning limits for scanning the desired area in the vicinity of the aircraft ”. In their invention, Tinkel et al. make use of adjustable scan limits to define the scan area.
In US Published Patent Application No. 20020180636 A !, Lin, Chian-Fang et al. show a passive tracking / alignment processing method that provides information from passive detectors and associated tracking control devices and the integrated GPS / IMU navigation system, to produce the three-dimensional information of position and speed of a target. The passive tracking / alignment processing method includes the method of producing two or more sets of measurements of the direction of a target relative to a carrier, such as azimuth and elevation angle sets, from two or more synchronized sets. of passive detectors and associated tracking control devices, installed in locations other than the carrier, calculating the target range vector measurements with respect to the carrier using the two or more sets of direction measurements, and filtering the vector measurements
ES 2 312 971 T3 range to estimate the information in three dimensions of position and speed of the target. Use is made of passive detectors, but two or more synchronized sets of passive detectors are required.
US Patent No. 5,825,480 to Udagava et al. relates the calculation of a line of sight that crosses the digital terrain map and describes that "The CPU 31 reads the data in relation to the address stored in the memory section 33 and, from this data and the information of the topographic map , retrieves a coordinate of a position that initially crosses the earth's surface in this direction (S5<sub>5</sub> in Figure 3). Specifically, it calculates the position in which the line that extends from one's own position to the direction of observation initially crosses the surface of the earth ”.
US Patent No. 6,064,942 to Johnson et al. they generally refer to a direct observing system and method, and more particularly to an enhanced precision direct observing system using a satellite positioning system retriever integrated with a laser range finder and compass. Position can be used with the target position estimation program for improved target position estimation, recognizes the error problem, and lists measurement errors, systematic errors, and operator errors. Johnson et al. disclose a laser range finder, specifically an active finder device.
In "Terrain intervisibility - believe it or not?" Stiles deals with the inter-visibility of the terrain, with respect to the visibility from an enemy point of view, of a helicopter hidden or not by the characteristics of the terrain. Stiles uses a mathematical method for determining inter-visibility, by developing a number of real-time inter-visibility and probabilistic inter-visibility functions using hybrid or multi-definition techniques and algorithms to have the best possible results for a given set of computer resources. Stiles enumeration provides results from algorithm-based calculations and statistical analysis.
In "Computational ground and airborne localization over rough terrain", Yacoob et al. describe a laser range finder, specifically an active device. Yacoob et al. They further indicate that the points that fall on the surface of the DTM and are within the elevation error range constitute the active-set (AS). The implementation of distance calculations is then run for each point in the active set, then all points on the ground surface are checked to determine if they all fall within the cone of uncertainty, and finally, the visibility of all points is examined. Points identified above as falling within the AS's cone of uncertainty.
US Patent No. 4,954,827 to Baird et al. lists a passive system and method whereby data (including longitude, latitude, and altitude) and flight position from a detector platform and stored terrain data are used to calculate an estimated range from the platform for a ground-based target or threat, and the estimated range is then processed using a Kalman filter to increase the accuracy of the calculated range. Baird et al. also describe a unique application of the Kalman filter for passive positioning, using the target range, found from the intersection of the LOS vector with the digital terrain data, as a measurement quantity for the Kalman filter. . Baird et al. they work with mathematical tools such as the Kalman filter.
UK Patent No. 2254214 A to GEC Avionics Ltd. relates to an imaging system and in particular relates to aircraft imaging systems for discrimination between different sizes and shapes of objects viewed at different scopes. GEC Avionics Ltd. also describes a radar altimeter, specifically an active device.
US Patent No. 6,418,371 to Arnold describes a traffic guidance system for the control, guidance and / or optimization of traffic movements, in which a detector is provided to detect the momentary traffic situation. The detector comprises a radio receiver and / or a receiver for optical signals and / or a receiver for acoustic signals emitted by road users.
US Patent No. 6,343,245 to Degnan refers to a micro-altimeter that measures position or range with high precision from an orbital vehicle. The micro-altimeter has a low-power solid-state laser that generates pulses at a speed greater than 1 kilohertz. The pulses are supplied to a small telescope that sends them to a surface of the planet and receives the reflections returned. A high-efficiency photon detector measures the received photons and supplies the received photon signals to a process that performs a time-based bit comparison to find the time of flight and hence the range.
US Patent No. 6,668,218 to Bulow et al. describe a method for estimating a minimum range for a target with respect to a first point of interest, comprising obtaining three displacement data points, which uses the three displacement data points to determine a velocity contribution Vos of a first point of interest at a distance from a relative velocity vector during a period of time ranging from t0 to 0t0 ': determining a thetabeta angle as defined by offset relative to the vessel itself and heading to the point in time of closest approach to a second point of interest; and that calculates a minimum range using a predetermined formula.
ES 2 312 971 T3
Description of the invention
The problems solved by the present invention are of two types. First comes the problem of passive data acquisition and reaching a sighted target, without emitting radiation. The second problem is that starting from an approximate North direction, you quickly get an accurate North indication, where accurate is defined as ± 3.4 '(1 mil).
The second problem is solved by two different methods. The first method uses the PTAS as a building block fed with actively measured range data toward a baseline target. A North Finding Procedure (NFP) supports the evaluation of both calculated and measured data to derive a North with precision. The second method obtains super-rapid north finding (SRNF) based on the inherent capabilities of the PTAS when a single target is available, as will be described below.
The first problem is, therefore, acquiring the data from the target without emitting signals, such as those radiated by an RF device or laser to prevent others from detecting the observation. To solve this first problem, the invention uses a system of acquisition of data of the target (PTAS, of English "Passive Target Acquisition System") with visual means, operated from an observation position, with additional means to accept as input data, the location of the observation point, the elevation angle and azimuth angle of the target as well as additional means to process the input data obtained in conjunction with a DTM (digital terrain model). The terms DTM, DTM database, and DTM surface are used interchangeably below, and thus the terms observation location, observation position, and observation point are used.
The PTAS processes the input data and calculates the point of intersection of a line of sight (LOS), also known as a display vector or simply a vector, which starts from the observation point and goes towards the target, where the point of intersection indicates the location of the target. Since the target is now a known point on the DTM surface derived from the DTM database, the target data is also known and available in digital format for further processing even for transmission of the data if required. want. The operator is presented with a screen of the DTM on which the target is marked, and on which one or more different maps or photos can be superimposed, such as for example a topographic map, satellite map, an ortho-photo or an aerial photograph. . The terms line of sight (LOS), display vector, and vector are used interchangeably below.
It is taken for granted that the reference to the screen or the screen module, or the presentation on the screen, refers to both graphic and alphanumeric data, or information related or not to graphic information. Target data and associated information are defined as desired in relation to its content and presentation. The operator can choose to view the information that he wants either only as graphical data or as numerical data or both, by means of the aid of the input / output unit referred to above.
The PTAS also accepts as input various inaccuracies in the input data, such as instrument inaccuracies in azimuth and elevation angle, which are displayed on the screen in an area of uncertainty or error area, related to the target location, in addition to the calculated target location. This characteristic is obtained by defining measurement inaccuracies as an envelope surrounding the display vector, where the term envelope is used as a generic name for a three-dimensional shape representing measurement inaccuracies. The calculation of the intersection of the envelope with the contour of the ground surface of the DTM is displayed on the screen as an error area associated with the indicated target.
It sometimes happens that the display vector runs into a first terrain shape, say a first hill in the foreground, which partially obscures a second hill in the background, so the envelope that surrounds the display vector marks the contour of the surface of the DTM terrain both on the hill in the foreground and on the hill in the background, forming two different error zones separated from each other for the same objective. To the operator this is a warning that the target may lie in either of the two error areas, and that the range to the target may vary accordingly.
Furthermore, when the envelope surrounding the display vector leaves more than one trace on the terrain, a warning is provided that a "dead zone" or "hidden terrain", or a strip of terrain separates both traces, hiding entire surfaces of the view. Such knowledge is of great importance to search units, both for the rescue of survivors and for the arrest of traffickers.
Obtaining an accurate North reading is a second problem. The PTAS is effective as a basic building block, coupled with an NFP precision North search procedure, for fast determination of the North direction with precision. In this case, an approximate azimuth is sufficient when provided as input to the PTAS, although an active range measurement device is required, such as a Laser Range Finder (LRF). Based on the approximate azimuth reading and a few suitably chosen datum targets on the DTM, a span of each datum target is calculated by the PTAS and stored in memory. LRF readings are then taken
ES 2 312 971 T3 of the same reference targets, according to the data calculated by the PTAS, such as azimuth and elevation towards the reference targets, and stored in conjunction with the ranges of the calculated reference targets respectively . The NFP is then driven to find a common deviation factor that, when applied as a common correction factor, will adjust the azimuth of the calculated and measured ranges. The common correction factor is the correction factor by which approximate azimuth readings must be corrected to accurately indicate a north direction.
The method and system of the present invention is operated continuously from an observation point, which is land-based, transported by sea, air, or space-based. Typically, a stabilized platform is favorable for deployments that are handled on the move, on land, at sea, in the air, and in space.
PTAS development prototypes have been successfully handled in four specific fields of operation, namely transport, military, paramilitary and search and rescue applications. In relation to transportation systems, specifically for navigation, collision avoidance and coastal navigation. With the military, as attachments for items that are carried by hand such as personal binoculars and light weapons, air vehicles with and without a pilot, including observation missiles and balloons, and also for the designation and tracking of targets. The police, border patrols, and customs units have adopted the PTAS primarily for observation and intrusion prevention purposes, as it has been tested for search and rescue activities, and determination of the range and point of navigation.
For the field of land-based uses, the time required for the deployment of commonly used systems varies between 2 and 5 minutes from arrival at the observation point to acquisition of the target data, whereas with the present invention it is not possible. requires more than a minute.
The following results were collected in 153 tests carried out with development units, for the passive measurement of the scope under various conditions: in 142 cases, representing about 92% of the situations, the target and scope data were calculated with an accuracy of ± 20 m, for ranges between 100 m and 10,000 m. Six additional target data readings, or 4%, were correct within ± 50 m, while the remaining five readings were out of range by more than 100 m.
It is an advantage of the present invention to provide a method and system for passive acquisition of target data, without the emission of detectable radiation.
Furthermore, the present invention makes it possible to avoid the high cost, weight, volume and maintenance costs of the LRF device.
Another advantage is the display of error areas on the screen due to inaccuracies in the input data, consequently "dead areas" are detected and indicated as such.
A further advantage of the present invention is the ability of the PTAS to operate continuously, in contrast to the intermittent operation of an LRF.
Furthermore, an NFP is implemented to quickly accurately point North, even when using approximate azimuth input means.
An additional advantage is the ability to operate out of hand, and on the move, on land, sea or in the air, where movement refers to both the movement of the PTAS and the target. In other words, the system can deduce precise target data with great efficiency, both when the PTAS is in motion and when it follows a moving target.
Summary
It is an object of the present invention to provide a method and system for passive target data acquisition (PTAS) for passively viewing the target from an observation point so that target data is acquired from it and from the associated information. The target data is for example target range, azimuth angle, elevation angle and target location. The associated information is any additional information such as a navigation point, altitude, and particular data. Target data and associated information displayed on a screen in graphical and alphanumeric representation are available for output in digital format and ready for transmission.
Thus it is an object of the present invention to provide a method using a passive target data acquisition system (PTAS) operable from an observation point to passively view a target. The PTAS comprises:
passive observation means coupled to a navigation device and azimuth and elevation angle measuring devices
ES 2 312 971 T3 a computer module operatively coupled to a DTM database module, to the observation means, and to a display.
Understanding the method the stages of:
measuring the location data of the observation point, and the azimuth and elevation angle towards the target, and supplying the measured data to the computer module and the on-screen display of both the observation point and the target on a surface corresponding DTM derived from the DTM database.
The method being characterized by understanding the stages of:
directing a vector towards the target and defining an envelope surrounding the vector originating from the observation point, and an envelope mantle distanced from the vector proportionally to the measurement errors, the execution of a PTAS computer program on the module computer to calculate the intersection points of the vector and the envelope with the DTM surface, and represent the intersection points and associated information on the screen, with which the data of the objective is acquired passively to avoid the emission of radiation.
The method further comprises the steps of executing the PTAS computer program to deduce a distance separating between the selected intersection points on the DTM surface, and deriving a range measurement that separates the observation point from the target. Furthermore, the method and system further comprise the steps of operating continuously to continuously derive the measured and calculated data, and operating continuously to continuously provide the target range, the target location data, and associated information.
A further objective of the present invention is to provide the steps to detect the existence of dead zone (s) distributed along the vector, between the observation point and the target, and to indicate the zone (s) dead (s) on the screen. In addition, the system and method comprises supplying the PTAS computer program with selected data comprising the location of the position, the length of the LOS vector, the azimuth and elevation angles, and the execution of the computer model of the PTAS to show the dead zones of the terrain and the associated information, according to the selected data.
Another objective of the present invention is to provide the visualization of the target from an observation point located above the surface of the DTM and located on an air transport platform, on land, at sea, in the air or in space, and fixed on a stabilized platform if desired.
Yet another objective of the present invention is to provide a system and a method to quickly find a North direction with precision, comprising: obtaining at least an approximate reading of the North direction for input into the computer module, and characterized by understanding the stages of:
run a North search procedure computer program on the computer modules to determine the sector of the observation area, dividing the observation area into sub-sectors and defining the reference targets, use an active range measurement device to actively measure the range from the observation point to at least two reference targets, supply at least two actively measured ranges to the computer module, and running the NFP computer program to calculate the deviation in the azimuth data at at least two reference targets by respectively associating the range as calculated by the PTAS and the range as actively measured, to derive a factor common azimuth deviation that provides a correction factor for accurate North indication.
This comprises automatically dividing the observation area into sub-sectors, and randomly selecting a reference target in each of at least two non-adjacent sub-sectors, and defining a selected reference target as a locus. for which every small azimuth deviation of the display vector represents a large change in range.
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The system and method further comprises the steps of:
Run the NFP computer program to calculate whether the observation point location adjustment reduces the value of the common deviation factor, and adjust the observation point location when the calculated adjustment accordingly reduces the deviation factor value common.
Brief description of the drawings
To understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
Figure 1 is a schematic description of a DTM known in the art, Figure 2 is a schematic architecture schematic of a passive PTAS target data acquisition system, Figure 3 is a schematic describing data flow respective computer module, Figure 4A a schematic illustration of the elevation angle as measured by the PTAS system, Figure 4B is a schematic description of the azimuth angle as measured by the PTAS, Figure 4C is a schematic description of the imaginary envelope shown as a cone surrounding the display vector, outlining the measurement imprecision associated with the system , Figure 5 is a schematic description of the basic geometry for finding the intersection points as defined with the PTAS, Figure 6A is a side elevation showing two error zones, Figure 6B is an illustration of a screen showing two error zones, Figure 7 is a flow chart of the succession of stages by which the acquisition is performed passive target data of the invention, Figure 8 is a process flow diagram of the intersection with the surface of the DTM, Figure 9 illustrates a procedure to define a North procedure with precision, Figure 10 presents the steps for evaluating deviations from the selected benchmarks, Figure 11 draws a scenario for the selection of benchmarks, and Figure 12 is a detailed flow diagram of a search procedure. of a North with precision.
Best ways to carry out the invention
As seen in Figure 2 now referred to, a passive target data acquisition system (PTAS) 18 of the invention contains a computer module 20, a topographic or DTM database 22, a link to such a database, a set of passive data acquisition modules 24, 26 and 28, and a display module 30, or display 30. The general arrangement described schematically in Figure 2 indicates the connections of the topographic database and the acquisition modules, with the associated computer module, to which passively collected spatial data is supplied, as will be explained below. As noted above, the display media is considered to be inherently included but is not described, as it is well known in the art. The terms DTM, DTM module, DTM database, survey database are used interchangeably. A DTM surface and a DTM surface contour are derived from the DTM module.
The passive acquisition of data collected at the observation point is in contrast to the active acquisition of data, which is related to the means of radiation emission. Sometimes it is desirable to hide the location of the observation point and avoid the emission of radiation. The advantage of passive data acquisition means is that they are practically, or at least much more difficult to detect than active data acquisition means, which generally emit some type of radiation, which others can possibly detect. Another advantage is the low cost of the system, when compared to the cost of an active range measurement device such as an LRF.
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The PTAS locates a target in three-dimensional space defined by an existing DTM database, using a TAP (Target data Acquisition Process) process. The information obtained through the passive data acquisition modules of the PTAS is used to define the origin and direction of a vector v. The origin of the vector v is the observation point with the PTAS, the origin location of which can be measured by a navigation data device, typically a GPS (global positioning system) receiver, as explained with reference to Figure 3. Typically , the computer module 20 receives the location data from the navigation device or data source such as a GPS receiver 44. The elevation angle to the target from a suitable measuring device, such as a theodolite 46, and the azimuth angle data from a bearing measuring device, possibly a compass 48, but preferably a better resolution bearing measuring device . The term elevation is used as a general expression regarding the measurement of an angle in the vertical plane. The elevation angle is taken as positive up the horizontal plane passing through the observation point and negative in the opposite direction.
The PTAS resides at the observation point taken as the origin of the DTM for the purpose of calculations. The PTAS operator is present on site or located at a remote station. The vector v is the line of sight (LOS) from the observation point to the target. As stated above, it is taken for granted and it is then assumed that the PTAS has to be mounted first, if necessary, has viewing means, powered and leveled, before being operational.
The elevation angle is illustrated in Figure 4A now referred to. Figure 4A illustrates a cross section through the terrain model, the straight line 54 or line of sight (LOS) that connects between the observation point 56 where the PTAS resides, and the target at point 58. The straight line 54 and horizontal line 60 form an angle δ, which is the elevation angle. The azimuth α is drawn in Figure 4B which refers to a topographic map. Azimuth α is the angle between North N, indicated by a date marked N, and LOS to the target at point 58, as seen from observation point 56.
Once the passively obtained spatial information, namely the position, or the location of the observation point, the elevation angle and the azimuth angle, has been entered, the computer module can calculate the intersection point of the vector v with the surface of the DTM derived from the DTM database. This means: the point of intersection of the vector v with the contour curve of the terrain DTM in the vertical plane where the vector v resides: since the DTM is a discrete model, with a typical distance of say 10 m between each point height accuracy for each sample point is typically ± 5 to 10 meters. Interpolation algorithms are applied to define a denser coverage of the area.
Bilinear or cubic algorithms can be used to calculate interpolation points. Bilinear interpolation generates a representation of the terrain surface constructed as flat quadrilateral elements, each having a corner with a common z coordinate of the DTM. This means that two opposite sides of the quadrilateral element are aligned with the x-axis while the other two perpendicular sides of it are co-directional with the y-axis. Cubic interpolation is obtained by launching a geometrically continuous plane above the z coordinates to approximate several DTM points as closely as possible.
Measurement inaccuracies associated with data acquisition modules are contained within the volume of a virtual envelope surrounding vector v. In the Figures, the shell is illustrated as a solid cone for the purpose of simplifying description. Figure 4C is a side elevation of a cut section in a vertical plane through the contour of the DTM surface, through the LOS, and thereby through the cone. The smaller the errors introduced by the data acquisition modules, the sharper the cone vertex angle will be, and thus the closer the cone mantle will be to the LOS. As seen in Figure 14, the cone is drawn in symmetry around vector 70, or LOS, that it wraps around. Vector 70 is joined between the origin O, marked as the observation point 56 containing the vertex of the cone, and the target T indicated as point 58. From observation point 56, here the origin O of the DTM coordinate system, vector 70 points toward target 58. Lines 62 and 64 mark, respectively, the upper and lower generatrix of the cone cut section. The envelope drawn as a cone in the Figures is intended to represent a volume contained between lines 62 and 64. Lines 62 and 64 reside in the cone mantle, or envelope mantle, that encloses the envelope.
To locate the target, an iterative calculation process is applied, using two pointers implemented concomitantly. A first vector moves on the DTM, and thus along the contour curve of the terrain surface itself, which is the vertical projection of vector 70 in the vertical azimuth plane on the DTM. The first pointer starts from the projection of the origin O onto the DTM, and continues in the direction of the measured azimuth. A second pointer moves along vector 70. Both pointers are co-linear on vertical with the first pointer. After a number of iteration stages, both pointers are brought together. At the intersection of vector 70 and the terrain contour curve of the DTM, the target T is then found. This is further explained in Figure 5 to which reference is now made.
Instead of using pointers, or an iterative intersection find process, any other method for the same purpose is practical. For example, a fully analytical solution can be applied when the surface of the DTM is defined analytically, although any other suitable approximation method is also useful.
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In Figure 5 an imaginary point P moves in successive iteration stages on the horizontal 60, which is oriented in the direction of azimuth and is vertically coplanar with the same point in each iteration stage, a normal to the horizontal 60 passing through the point that intersects both vector 70 and the DTM, or the TCC (Terrain Contour Curve) contour curve. The first pointer Pv, not marked on Figure 5, indicates the intersection of the horizontal normal 60 with the vector 70, the second pointer Pd, not indicated in Figure 5, indicates the intersection of the normal through point P with the contour curve of the TCC terrain of the DTM. In the first iteration stage, point P is moved to location 76 on horizontal 60. Since vector 70 is above the DTM terrain contour curve, both pointers Pv and Pd do not meet as they are separated by a distance along the vertical z axis of the DTM. The fact that both pointers Pv and Pd do not coincide, or do not meet, means that the target T has not been detected. Therefore, the iteration process continues.
In the next iteration stage, point P on horizontal 60 moves from position 76 to position 78. Consequently, Pv on vector 70, and Pd on the TCC terrain contour curve of the DTM, advance at a new location. Both pointers reside on the horizontal normal 60 through position 78. No match found yet, since both pointers Pv and Pd are mutually separated by the vertical distance about their common normal. In the same way, a further iteration step of point P from position 78 to opposition 80 has the same result, since Pv and Pd do not yet coincide. The iteration process continues in the same way in further steps, from position 80 to position 86. The target T on vector 70 is finally at position 86 where both Pv and Pd coincide. However, this target point is theoretical, since due to system errors, the real target can be located anywhere in an error area circumscribed by the intersection of the cone mantle with the DTM, actually the contour of the surface of the ground. This error area is delimited by a limit of the target area formed by the intersection of the cone mantle or by each mantle guideline, with the DTM.
Horizontal 60 is used for explanatory purposes only. In fact, the pointer Pd moves iteratively, and the pointer Pv follows it accordingly on the same vertical. The iteration stages are adjusted to ensure small and reasonable consecutive jumps throughout the DTM, and thus along the contour curve of the TCC terrain surface of the cutting section, say in steps of every 10 cm , or as desired.
Still referring to Figure 5, at position 84, the lower cone mantle guideline, represented as line 64, will provide the target point Tc closest to observation point 56 on the limits of the target. The farthest point from the target Tf is on line 62, which is the directrix of the highest cone. Other points on the edge of the target area are determined by iteratively continuing the pointer junction search process described above for other cone mantle leader lines. It is understood that the smaller the system errors, the smaller the error area. If the terrain contour were a geometric plane, then the error area would be a geometric cone section, and thus an ellipse for a plane inclined with respect to LOS or vector 70.
In reality, the error area is shown to an operator on the display module in the form of a trace, or closed curve that defines the area of uncertainty where the target resides. However, depending on the convolutions of the DTM surface contour and the angle of incidence of the LOS on it, the area of uncertainty for a single sighted target can be defined by more than one closed curve. Referring to Figure 6A, a cross section of the DTM terrain surface and the cone is shown in a vertical plane through vector 70. The TCC terrain contour curve of the DTM terrain surface represents a curve rugged oscillating with peaks and valleys. As shown in Figures 6A and 6B, vector 70 first hits the first hill H1 to indicate a target T on it, while the upper and lower generatrices, respectively 64 and 62, intersect the contour curve of the TCC terrain at points 90 and 92 respectively. Point 90 and point 92 reside on, respectively, the first hill H1 in the foreground and on the second hill H2 in the background. Vector 94 is asymptotic with the top of hill H1 at point 941 and affects hill H2 at point 942. The uncertainty area as defined by the cone, will delimit a first error area 96 on that first hill H1 , up to the top of it, and also a second error area 98 on the second hill H2.
It is taken for granted in the description below that the reference to the displayed information, such as the display of error areas, refers to both graphical and numerical data, and in the same way to the associated information related in them, and that the operator must select the view of both or only of the graphical or numerical data. To receive the data relative to any selected point on the screen, the operator uses the input / output unit that is accepted to be available as standard equipment with the display devices.
Still referring to Figures 6A and 6B, it is thus possible to passively visualize a single target and obtain more than one area of uncertainty as the response. In such a case, the operator is shown a set of separate uncertainty areas on the display module, all as traces or closed curves aligned along the direction of the vector v or LOS. The topography of the DTM shown in Figure 6A is depicted as a summit elevation in Figure 6B, which depicts screen 88 as it appears to the operator. The objective T is indicated on hill H1 but the area of uncertainty covers a first plot 96 on that hill, and a second plot 98 on hill H2. Figure 6B illustrates more than one uncertainty area separated from each other, which is indicative of a "dead zone" between each pair of uncertainty areas. Although not shown in the various Figures, the numerical data, or related information associated with the graphical information, is also shown to the operator. I know
ES 2 312 971 T3 takes for granted in the description that the reference to a screen, or presentation on the screen, refers to both graphical and numerical data, or the associated information related to them and that the operator can select the view of both or just graphical or numeric data.
A dead zone is defined as a region of terrain hidden from an operator's view when the target is sighted along the LOS. It is up to the operator to decide in which area of uncertainty the target may reside. The existence of a dead zone is considered valuable information revealing the presence of hidden areas. For the benefit of the operator, the PTAS differentiates between an intersection of the cone mantle that delimits an error zone and the intersection of a vector v that indicates the target, and highlights this distinction on the screen.
Turning now to the inaccuracies of the system, it is now understood that the measurement inaccuracies in elevation and azimuth are of different value, thereby being delimited by an envelope in the shape of a four-sided pyramid. A section through it, perpendicular to the LOS, will show up as a rectangle rather than a circular base, in the case of a right cone as used for easier description. In fact, the term envelope is used as a generic name for a three-dimensional shape with a vertex at the observation point, possibly divergent towards the target, but proportional to the measurement imprecision, and wrapping the LOS along its length. For example, a four-sided pyramid, not necessarily square, can typify inaccuracy in azimuth and elevation. Actually, for the general case of an envelope, a cross section perpendicular to the LOS vector will provide a closed shape within limits. These limits represent the mantle or outer surface of the envelope. Each point of the cross section is best defined in polar coordinates. With the origin on the LOS vector, a vector radius and an angle defining each single point on the sheath cut section.
The iterative process of finding a target does not end when a first target is obtained, but adjusts to continue along the same vector v and cone mantle guidelines, until an end in the length of the vector is reached. This vector length is set in advance by the operator, for example as 10 km.
In practice, not only the intersection points with the DTM are valuable, but also the surface they delimit, as well as the distance between the delimited surfaces. The first intersection point created is that of the vector v that passes through the DTM, indicating a point on the target. When the contour of the DTM presents a succession of hills aligned along the vector v, then the vector v can intersect the DTM at more than a single point. One of those intersection points is the target. Other points of intersection with the DTM are those of the envelope mantle, whose intersection points delimit an area of uncertainty. Each point of intersection of the vector v with the DTM is accompanied by an uncertainty, one of which surrounds the target. That way there is always a target, but possibly more than one area of uncertainty. It is the separation between the areas of uncertainty, and therefore the distance between the delimited surfaces, which indicates the presence of dead zones. Detection of dead zones is very often of cardinal importance, for example in rescue operations, in civil engineering and in warfare.
The entire process of passive target acquisition according to the present invention is schematically described in Figure 7 to which reference is now made. In step 100, data is collected, including the azimuth and elevation angle to the target. And the position of the observation point on the DTM. Reference to an observation point above the DTM, such as on an airborne platform, is made lower. In step 102 a vector v is defined as having an origin at the observation point and the direction as defined by the azimuth and elevation angle. In step 104 a cone is defined, for simplicity's sake, having a vertex at the observation point, and a vertex angle corresponding to the errors of the system, relative to the data acquisition modules. In step 106 the operator defines a section of maximum length on the vector to be scanned for intersection with the DTM. The maximum section length is defined only once, at the beginning of the setting, for example as 10 km long. In step 108, the iterative search procedure for the intersection with the DTM is implemented. The intersection points, the LOS vector point, and the cone mantle points are found and displayed on the display module, for inspection by the operator, at step 110.
The DTM intersection procedure is outlined schematically in Figure 8 now referred to. In step 110 the assigned section is divided into segments. The first segment is selected in step 112. If desired, there will only be a single segment. Next, in step 114, intersection calculations are performed on the first segment, to look for fits or coincidences between the pointers on the vector line and on the generatrix of the envelope cone relative to the pointer on the DTM. Then, in step 116, the system checks if at least one match has been found between the pointers. If not found, control will proceed to step 120. If a match is found, then by step 118 the at least one match point is stored in memory and control flows to step 120. If this is the last segment or the only segment, then the procedure is terminated. . Otherwise, in step 122 the next segment is collected. Control returns to step 114 and calculations are carried out for the next segment in search of a possible match between both pointers. If desired, the entire default length of the vector v is considered as a single segment. In other words, the first and only segment is the maximum section length on the vector v to be scrutinized at the intersection with the DTM. This method has its advantages.
It is understood that the coincidence or fit of the pointers Pd and Pv is accepted to exist when their mutual vertical distance falls within the predefined tolerances. For example, even when both pointers are still separated by
In a few centimeters, such a small discrepancy can be considered as a pointer match, thereby achieving a valid pointer match.
In general, when a fit or match is referred to below, it is considered a tolerance range, since in real life there is no advantage in asking for perfect mathematical accuracy. The PTAS computer program is also a powerful tool for discovering and mapping dead terrain zones during the planning stage of a mission in advance of actual execution. For this purpose the PTAS computer program is fed with data relative to the region selected to be scanned, and is executed to display the results. An operator can enter a location point of a planned observation point, define the length of a LOS vector, and then select a region to be scanned by defining the azimuth and elevation angles as parameters. As a simpler example, when a single azimuth angle and a single elevation angle are entered, then only dead zones along the LOS vector are calculated and displayed. To obtain the information on the longitudinal section through the terrain along a vertical azimuth plane, the same calculations are repeated but for a succession of elevation angles within the data limits. To cover an area of the terrain, both azimuth and elevation parameters are entered as variables, within a chosen range of angles. Other combinations of observation point positions, LOS vector length, elevation angle, and azimuth will serve many additional purposes.
The observation point from which the PTAS is operated is not necessarily a static position, but if desired, it can be a mobile position. The PTAS is preferably mounted on a stabilized platform when implemented as a device that operates on a moving vehicle. In general, the PTAS is compatible for use on a platform, static or mobile, on land, at sea, in the air or in space. When built in accordance with current art practice, and when integrated with existing systems, the PTAS is no larger than a small handheld camera, making it practical for mounting with binoculars and portable personal weapons, and with unmanned aerial vehicles.
When operating from a mobile platform, such as from an unmanned aerial vehicle, the introduction of additional data and computer programs is necessary to take into account the path or trajectory of the platform and the movements of the spatial position of the platform.
Northern Search Procedure (NFP)
PTAS capabilities in implementing the Target Data Acquisition Process (TAP) can be used for additional purposes. In a related process, a North Rapid Search (NFP) procedure is implemented using the PTAS described herein above in conjunction with an active range finder, typically an LFR range laser seeker. The system is used to refine an approximate measurement of North, as obtained by a magnetic compass, to a highly accurate, improved North indication. The NFP uses Reference Target (RT) sightings, which are associated with both passively calculated ranges and actively measured range, to calculate a common angular correction factor, and quickly obtain an accurate North reading. in the place of the observation point.
To begin, the NFP uses a Data Input Procedure (DIP) as explained below, with reference to Figure 9. The DIP 160 accepts input from an approximate measurement of North on the step 162. The target data acquisition process, or TAP, then operates to calculate the range, or distance, to the reference target A as defined by the operator in step 164. At step 166 the DIP accepts input from an actively measured reference target A range, as measured by the aid of an LRF laser range finder. In step 168, the deviation between the range calculated by the TAP and the range measured by the LRF is used to calculate a common azimuth correction factor. For this purpose, the sector of the observation area is decided and divided into sub-sectors. Selected subsectors are scanned for a match between the calculated and actively measured baseline target A, or RT A, hits. As explained in detail below, for each hit-range found, the TAP calculates the angular deviation that separates the azimuth at RT A and the azimuth at the location with the coincident range. The deduced angular deviation is stored in step 170. The DIP is repeated several times for different selected reference targets A chosen in different predetermined sub-sectors. However, the NFP works well even with a single RT A.
In the procedure described in Figure 10 now referred to, a common deviation factor is calculated for the various selected reference targets A in step 190. Once collected, the deviations are evaluated in step 192. This is performed for example by defining an allowed tolerance, and declaring a valid match when the ranges are within tolerance limits, as in step 194. It was previously stated that the fit or match refers to a practical predetermined range of tolerances and is not mathematically absolute.
If the calculated common deviation factor is found and is within tolerances, then a correction factor is produced to establish the precise North, in step 196. If the common deviation factor was not found, then the DIP is reactivated and it is operated on a new set of reference targets chosen in different but not adjacent predetermined sub-sectors.
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The system of the invention searches for the DTM and selects the optimal reference targets so that the best possible increase in precision is achieved. The general scenario of the selection of the reference target is described according to Figure 11, to which reference is now made. The PTAS observation facility at point 230 looks approximately in the direction of arrow 232. In the area of interest an observation zone sector 234 is assigned which has two radii as zone boundaries, 236 and 238, respectively. Then, the sector of the observation zone is divided into several sub-sectors 239, typically 10, by a procedure possibly performed automatically by the TAS computer module, or by the operator. Within each subsector 239, a single reference target (RT) is searched for in the DTM, each one being defined as a locus. Such a locus is a place where every small angular movement of a radial slider 240, in sector 234, in the direction transverse to azimuth, as represented by double arrow 242, encounters large changes in range. Typically, the subsectors 229 in which an RT is selected are separate and not adjacent, as highlighted by the X marks within the sector 234. When desired, the NFP is operated with a single RT reference target, although typically three RTs in non-adjacent subsectors 229 are preferred.
To operate the NFP, a PTAS is needed as described above, an NFP computer program running on the computer module, and an active ranging device such as an LRF. It has been described above that the PTAS works independently, but this is not true for the NFP, which requires the support of the PTAS to function.
Referring to Figure 12, the input data is collected at step 302, including the position of the observation point, and the azimuth. Typically, this input data is obtained as follows. For the location of the observation point, which is considered as the origin of the set of Cartesian coordinates on the DTM, a GPS device (global positioning system) is practical. For azimuth, a compass or similar device provides the necessary indication, for an approximate but sufficient precision of about ± 34 '(10 mil). Optionally, input is received from other sources.
Then, in step 304, it is up to the operator to delimit the sector of the observation zone on the DTM, as previously described with reference to Figure 11. If the operator does not do so, then the NFP will automatically adjust a sector 360 ° observation area. The delimitation of the sector is obtained by defining a sector radius, as the maximum observation distance and by setting the radial limits. The operator, or the computer module, will divide the observation zone sector 234 into subsectors 239, typically ten.
At step 306, the NFP computer program now searches the DTM to select a singular RT reference target in say three non-adjacent sub-sectors. Such a singular RT is a locus typified by a rapid change in range for a small angular deviation in azimuth. The PTAS then calculates the RT data for each singular RT, ie the calculated range, elevation and azimuth whose calculated RT data is stored in memory. More precisely, the PTAS calculates the data for the RTs in each subsector 239 and stores that data in memory. Then in step 306, three sub-sectors are randomly chosen, and one RT is selected in each of the three sub-sectors.
In turns, at step 308, the range of each RT is now measured, this time actively with an LRF, and stored in memory in association with the respective RT. The LRF measurement is taken by sequentially pointing the display device at each RT. However, the operator is not aware of the location of a real-life terrain RT as seen from the observation point and hence requires guidance, possibly provided in at least two different modes. The azimuth and elevation needed to point the LRF towards RT, which were derived in step 306, are now used to guide the operator. As a first way, the dates on the screen are pointed in the required viewing direction to guide the operator who will direct the instrument until a feedback signal indicates "on target". At that point the operator will "fire" the LRF and obtain a range. This sequence is repeated for each RT. A second way takes advantage of the integral control mechanisms with the display device to automatically take care of pointing the instrument, and positioning the cross on the RT, then, when it is "on the target", it signals the operator to actively measure in scope. Alternatively, active range measurement is performed automatically. Again, this sequence is repeated for each RT. Each LRF reading is stored in association with the respective RT.
Guidance given to the operator to aim towards the RT as calculated by the PTAS with respect to imprecise azimuth indication will result in a specific accuracy of the LRF range measurement. However, since the azimuth is not accurate, the LRF measurement, while accurate, will not relate to the RT but to another location, in a nearby direction.
Until now, the NFP has stored passively calculated RT ranges as well as actively measured ranges, based on an imprecise North indication, which is certainly not the required precise North direction. More likely, the passively calculated range and the actively measured range will give different values. This discrepancy is the result of the fact that the computer program sees the azimuth as a precise absolute value, whereas in reality it is nothing more than an approximate and imprecise azimuth, which was measured with, say, the aid of a compass.
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It is now the task of the PTAS computer module to find by how much the RT LRF reading has deviated by angularly adjusting the approximate measured azimuth discrepancy with precise North. If it is advantageous to reduce the value of the angular discrepancy, the origin of the coordinates on the DTM can be repositioned within the limits.
At step 310, the NFP operates the PTAS to scan subsector 239 containing a selected RT reference target, through a typical imprecision angle of about ± 34 '(10 mil), which is the angle compass imprecision. The scan is directed transversely to the direction of each calculated RT. What the NFP is looking for is to discover the angular deviation between a calculated point on the surface of the DTM, which has the same range readings as the LFR. Thus, when a match is found where the range to an actively measured RT coincides with a point in the respective subsector 239 on the DTM, the angular deviation between the azimuths towards the RT that has been actively sighted and how they have been calculated are stored in memory. More precisely, it is the angle between the azimuth of a point on the surface of the DTM, which has the same range as actively measured by the LRF, and the original approximate azimuth reading towards RT that is calculated by the PTAS. The NFP will then repeat this operation for each RT and eventually try to find a common azimuth deviation factor, or CDF (Common Deviation Factor). When applied in succession to each RT, the CDF will provide a common correction factor by which the approximate azimuth indication must be adjusted to indicate the direction of North accurately.
In step 310 the transverse scan operation is repeated for each RT in the three separate non-adjacent subsectors. A CDF is searched for in step 312, and if found, it is saved, as by step 314, and used for adjustment.
If desired, for better precision, after the deduction of a CDF, the NFP can also check whether the corrections, within predetermined limits, of the input data in relation to the location of the observation point, will help to obtain a reduced CDF value. If that is the case, then the location of the observation point is also corrected. This last optional stage is not detailed in Figure 12.
Once a CDF is found, then the NFP comes to an end. As described above, the match is accepted as such within predetermined tolerances.
If a CDF has not been found in step 312, then control returns to step 306, where a different set of three separate non-adjacent subsectors is selected, and an RT is chosen in each subsector. In the field, the NFP typically determines a CDF in a single search loop, but two or more CDF calculation loops are possible under difficult conditions.
The second method called Super Fast North Search - SRNF, allows the operator to quickly find the precise North in relation to a specific real-life sighted target, or SST (Specific Sighted Target), also detected on the screen. of the PTAS. In this way, the operator can manually correct the calculated target data to fit the precise data provided by the DTM.
First, the operator chooses a specific SST sighted target on the real-life terrain surrounding the observation point, and measures a raw azimuth of it, with a compass for example. The operator then guides the PTAS viewing or observing device (or observing means, possibly binoculars such as a telescope), to direct it to the SST and measure the location of the observation point and the elevation angle, which, together with the reading of the raw azimuths are entered into the PTAS computer program for calculation and display. Due to the approximate compass readings, the data calculated for the SST is not accurate and the result of the calculations is referred to as the Coarsely Calculated Target (CCT). The PTAS screen thus displays not the specific sighted target, or SST, but the roughly calculated target (CCT). The same screen also shows the SST somewhere on the surface of the DTM, probably near the CCT.
It is now the task of the operator to find the specific SST sighted target on the DTM surface displayed on the PTAS screen, and to obtain from it the precise azimuth towards the SST. The SST will probably be on the screen near the CCT. When the SST is on the screen, the calculated CCT data is corrected according to the precise azimuth of the SST, which is input into the PTAS computer module.
For those cases where the operator can immediately identify the SST on the PTAS screen, the process of obtaining an accurate azimuth towards the SST is even simpler. The operator just points the PTAS towards the SST, measures the location of the observation point, and finds the SST on the PTAS screen from where the precise azimuth is retrieved. At this stage the operator feeds back the precise azimuth to the PTAS.
Not only is the need for an LRF saved, but the method described above may take only about 30 seconds.
ES 2 312 971 T3
Industrial Applicability
The above description leaves no doubt as to the applicability of the invention in various branches of industry.
Those skilled in the art will understand that the present invention is not limited to what has been particularly shown and described hereinbefore. For example, various devices or data sources can be used to provide inputs to the PTAS and the NFP. Additionally, the PTAS is possibly purchased as off-the-shelf equipment, or assembled to integrate the various modes necessary to operate the invention. Still another possibility is to add and integrate it with existing systems, those missing modules, which are necessary for the operation of the invention. Separate modules can be integrated to form an observation system. For example, a simple observing system can be attached and integrated to a computer, a display, a GPS unit, or a compass and a laser range finder (LRF). When all the necessary modules are present in an existing platform, then all that is needed to implement the method and the PTAS system is the integration of the computer application programs with the computer module.
Contents9
10 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10
21 members in 7 offices
Priority claims5
| Document | Office | Kind | Date |
|---|---|---|---|
| 15470103 | Israel | A | |
| 15470103 | Israel | A | |
| 20030154701 | Israel | – | |
| 1547010304716000 | – | – | – |
| IL20030154701 | – | – | – |
Members21
| Document | Office | Kind | |
|---|---|---|---|
| WO2004079400A2 | World Intellectual Property Organization (WIPO) | A2 | |
| WO2004079400A3 | World Intellectual Property Organization (WIPO) | A3 | |
| EP1599771A2 | European Patent Office (EPO) | A2 | |
| US2005273254A1 | United States of America | A1 | |
| EP1599771A4 | European Patent Office (EPO) | A4 | |
| US7107179B2 | United States of America | B2 | |
| US2007010965A1 | United States of America | A1 | |
| WO2007080589A2 | World Intellectual Property Organization (WIPO) | A2 | |
| WO2007080589A3 | World Intellectual Property Organization (WIPO) | A3 | |
| EP1599771B1 | European Patent Office (EPO) | B1 | |
| AT407343T | Austria | T | |
| ATE407343T1 | Austria | T1 | |
| EP1974277A2 | European Patent Office (EPO) | A2 | |
| DE602004016294D1 | Germany | D1 | |
| US7451059B2 | United States of America | B2 | |
| ES2312971T3This record | Spain | T3 | |
| IL170442A | Israel | A | |
| IL173149A | Israel | A | |
| EP1974277A4 | European Patent Office (EPO) | A4 | |
| EP1974277B1 | European Patent Office (EPO) | B1 | |
| ES2420528T3 | Spain | T3 |
Numbers
- Publication
- 2312971
- Publication, DOCDB
- 2312971
- Publication, EPODOC
- ES2312971T
- Application
- 4716000
- Application, DOCDB
- 04716000
- Application, EPODOC
- ES20040716000T
Titles2
- Spanish
- PROCEDIMIENTO Y SISTEMA DE ADQUISICION PASIVA DE DATOS DE OBJETIVOS.
- English
- PROCEDURE AND SYSTEM OF PASSIVE ACQUISITION OF DATA OF OBJECTIVES.
Classification
- CPC, 2
- G01C21/005
- G01S5/16
- IPC, 11
- G01C21 00
- G01C3 02
- G01C17 38
- G01C21 26
- G01S
- G01S5 16
- G01S11 12
- G02B
- G05D1 00
- G05D3 00
- G06F17 00