USA As Represented by Secretary of the Navy

Roy F Wiegert

John Oeschger

Brian L Price

Kurt A Giardina

A magnetic anomaly sensing system and method uses two triaxial magnetometer (TM) sensors arranged in a one-dimensional array with the sensors' magnetic sensing axes being parallel to one another. The sensors are spaced-apart from one another along one of the sensing axes by a distance D with a midpoint between the sensors along the one sensing axis being located a distance Z from a reference datum. A processor implements an iterative process to include generating scalar magnitudes of a magnetic anomaly field measured at each of the sensors where the magnetic anomaly field is associated with a magnetic object. A scalar range from the sensors to the magnetic object is generated based on the distance D, the distance Z, and the scalar magnitudes. A magnetic dipole moment of the magnetic object is generated using the scalar range and the scalar magnitudes.

Magnetic anomaly sensing system using two triaxial magnetometer sensors

A magnetic anomaly surveillance system includes triaxial magnetometer (TM) sensors arranged at known locations in an array. A processor coupled to the TM sensors generates a scalar magnitude of a magnetic anomaly field measured at each of the TM sensors. The scalar magnitude is indicative of a spherical radius centered at the known location associated with a corresponding one of the TM sensors. The processor also generates a comparison between each scalar magnitude and a threshold value. The processor then determines at least one magnetic anomaly location in the coordinate system via a spherical trilateration process that uses each spherical radius and each scalar magnitude associated with selected ones of the TM sensors for which the threshold value is exceeded. One or more output devices coupled to the processor output data indicative of the one or more magnetic anomaly locations.

Magnetic anomaly surveillance system using spherical trilateration

A magnetic anomaly sensing system and method uses at least four triaxial magnetometer (TM) sensors with each of the TM sensors having X,Y,Z magnetic sensing axes. The TM sensors are arranged in a three-dimensional array with respective ones of the X,Y,Z magnetic sensing axes being mutually parallel to one another. The three-dimensional array defines a geometry that forms at least one single-axis gradiometer along each of the X,Y,Z magnetic sensing axes. Information sensed by the TM sensors is to generate scalar magnitudes of a magnetic anomaly field measured at each of the TM sensors, comparisons of the scalar magnitudes to at least one threshold value, distance to a source of the magnetic anomaly field using the scalar magnitudes when the threshold value(s) is exceeded, and a magnetic dipole moment of the source using the distance.

System and method using magnetic anomaly field magnitudes for detection, localization, classification and tracking of magnetic objects

A portable magnetic anomaly sensing system includes a non-magnetic support structure defined by a rigid beam and a rigid frame coupled thereto. Triaxial magnetometer (TM) sensors are rigidly coupled to the frame with one TM sensor being positioned at each vertex of a cubic space. Each TM sensor is positioned such that all respective X,Y,Z magnetic sensing axes are mutually parallel to one another. A data acquisition system is mechanically coupled to the beam such that any magnetic elements of the data acquisition system do not adversely affect accuracy of the TM sensors. The data acquisition system samples the sensed magnetic field data from all TM sensors synchronously with a timing signal. A processor is mechanically coupled to the beam such that any magnetic elements of the processor do not adversely affect accuracy of the TM sensors. The processor applies a magnetic scalar triangulation and ranging (STAR) processing scheme to the digitized magnetic field data in order to determine a position vector and a magnetic moment vector. One or more output generation devices are used to generate a human-discernable output to the position vector and the magnetic moment vector.

Portable magnetic sensing system for real-time, point-by-point detection, localization and classification of magnetic objects

A magnetic anomaly sensing system and method uses at least eight triaxial magnetometer (TM) sensors arranged to define a cubic space. Each TM sensor measures a local magnetic field associated with a target region and generates magnetic field data indicative thereof. The magnetic field data is processed in accordance with a magnetic scalar triangulation and ranging (STAR) processing scheme to determine a plurality of gradient contractions Cat a corresponding plurality of measurement points I to include at least at the center of each face of the cubic space. Gradient contraction pairs are defined for each sensors' X, Y, Z magnetic sensing axes. A directional derivative &#x2207;Cis determined using the gradient contraction pairs and the baseline distances therebetween. A unit vector, calculated using the directional derivative &#x2207;C, is used in determining a projection distance from each of the measurement points toward the target region.

Magnetic anomaly sensing system for detection, localization and classification of a magnetic object in a cluttered field of magnetic anomalies

A system for tracking a moving magnetic target uses a magnetic anomaly sensing system to continually determine magnetic gradient tensors associated with the target and converts the magnetic gradient tensors to gradient contraction scalars. A processor uses the magnetic gradient tensors and gradient contraction scalars to determine a minimum of bearing and range to the target. A velocity of the target is determined using the determined bearing and range at two points in time as the target is moving. To continually track with the moving target, the processor determines adjustments in elevation and azimuth using the magnetic gradient tensors and gradient contraction scalars along with bearing, range and determined velocities of the target. The processor can include a routine that determines range while accounting for asphericity errors introduced by the aspherical nature of constant magnetic gradient contours associated with the target.

Magnetic anomaly sensing-based system for tracking a moving magnetic target

A magnetic anomaly homing system and method utilize an array of four triaxial magnetometer (TM) sensors coupled to a non-magnetic platform. The four TM sensors are positioned at the vertices of a rectangular parallelogram. The magnetic field sensed at the four TM sensors is processed to generate complete gradient tensors and corresponding scalar gradient contractions thereof for four two-axis gradiometers formed by the array. The scalar gradient contractions define guidance control parameters used to steer the platform toward the magnetic anomaly.

Magnetic anomaly homing system and method using rotationally invariant scalar contractions of magnetic gradient tensors

A magnetic anomaly homing system uses an array of magnetic sensors coupled to a non-magnetic platform. The array is defined by a plurality of single-axis subsystems with each one thereof having two magnetic sensors spaced apart from one another. A processor coupled to the magnetic sensors generates a plurality of magnetic total field scalars that can be used to directly home in on a magnetic object from both long and short-range distances to the target. The scalars define guidance control parameters used to steer the platform to align the platforms's direction of motion with the magnetic anomaly.

Magnetic anomaly homing system and method using magnetic total field scalars

A system and method for magnetic anomaly guidance is provided. Triaxial magnetometer (TM) sensors are positioned at the vertices of an arrangement with an axis of the arrangement, being defined between each pair of the vertices. The arrangement is positioned on a support such that one of the X,Y,Z magnetic sensing axes for all of the sensors defines a forward direction of movement. The sensed magnetic field's X,Y,Z components of the TM sensors are processed to generate a partial gradient contraction associated with each axis of the sensor arrangement. Relationships between the partial gradient contractions are used to generate steering control commands for use by a steering system that is coupled to the support.

Magnetic anomaly guidance system and method

A magnetic anomaly sensing system uses triaxial magnetometer (TM) sensors arranged in a three-dimensional array. A processor coupled to the TM sensors generates partial gradient contraction data, and complete gradient tensor data and corresponding complete gradient contraction data. The generated data can be used to align the three-dimensional array with a magnetic target. Once the three-dimensional array is aligned with the magnetic target, the generated data can be used to uniquely determine (i) distance to the magnetic target, (ii) position of the magnetic target relative to the three-dimensional array, and (iii) the magnetic dipole moment of the magnetic target.

Magnetic anomaly sensing system for detection, localization and classification of magnetic objects

An active magnetic anomaly sensing and processing system has a plurality of transceivers positioned at known relative positions on a platform. Each transceiver includes i) a transmitter for transmitting a magnetic field towards a target to cause propagation of a magnetic anomaly field from the target, and ii) a sensor that produces a first output indicative of the magnetic anomaly field and background magnetic fields. A reference sensor, positioned further from the target than each of the transceivers' sensors, senses background magnetic fields and produces a second output indicative thereof. Each transmitter is activated and subsequently deactivated simultaneously to define a transmission time and a non-transmission time, respectively. Scalar magnitudes of each first output and the second output produced during the non-transmission time form quantities that are indicative of presence, location and classification of the target.

Active magnetic anomaly sensing array and processing system

Magnetic anomaly sensing system and methods for maneuverable sensing platforms

An active magnetic anomaly sensing system includes a transmitter for transmitting a magnetic field towards a target. The magnetic field induces magnetic moments in the target which cause a magnetic anomaly field to propagate from the target. A first sensor positioned a distance D from the target directly senses magnetic field strength and produces a first output. A second sensor positioned a distance (D&plus;d) from the target directly senses magnetic field strength and produces a second output. A controllable power supply is coupled to the transmitter for selectively activating and deactivating the transmitter. The first and second outputs are produced when the transmitter is deactivated. The second output is subtracted from the first output to generate a differential output indicative of the magnetic anomaly field propagating from the target. Means and methods are provided to synchronize the response characteristics of the sensors with one another, and to synchronize the transmitter with the sensors so that deactivation of the transmitter results in a near instantaneous detection of magnetic field transients by the sensors.

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Panama City, FL, United States of America

Roy F Wiegert