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Low Cost Magnetic Sensor for Mine Neutralizer Identification and Charge Placement


TECHNOLOGY AREA(S): Sensors, Electronics, Battlespace 

OBJECTIVE: Develop a low cost Tactical Decision Aid (TDA) magnetic or electromagnetic induction sensor to provide an additional identification (ID) capability for mine neutralizers in murky water or with limited communications link as well as a precise positioning capability for buried mine neutralization. 

DESCRIPTION: The Navy needs a Tactical Decision Aid (TDA) to assist operators with identifying underwater objects (particularly naval mines) based on available sensor data. Current mine neutralization systems present the operator with a continuous, real-time, video image of the target as the only identification (ID) capability. This capability can only be used when water clarity allows and when there is a high bandwidth fiber link. The next generation of mine neutralization vehicles may be fielded with a limited bandwidth communication link, which may utilize an untethered acoustic modem for communication between the deployment platform and neutralizer. In addition, there may be a low bandwidth link from the unmanned deployment platform to the Littoral Combat Ship (LCS), where the operator controls the neutralizer. The low bandwidth link would greatly reduce the number and resolution of the target images sent back to the operator for ID purposes. This technology can also be used to precisely position a neutralization vehicle over a buried mine allowing for reduced payload charge size and increased effectiveness. There has been considerable research conducted in the last 50 years on the use of magnetic sensors to detect and classify underwater objects. These typically have been large, power hungry devices that needed to have separation from the platform to escape the platforms self-noise. Vast technological leaps in the last 10 years have occurred for magnetic heading sensors and electromagnetic induction arrays, resulting in increased accuracy and sensitivity as well as reduced cost, size, and power requirements. This effort will research low cost options, less than $100, for magnetic sensors based on anisotropic magneto resistance (AMR), giant magneto resistance (GMR), magnetic tunnel junction (MTJ), extraordinary magneto resistance, Faraday rotation, or optically-pumped atomic transitions, or for electromagnetic induction sensors, which will work in parallel with the vehicle heading sensor to provide an indication of the Mine Like Contact (MILCO) magnetic content. The sensor could be mounted on a lightweight extendable boom, which would allow separation from the neutralizer platform to escape self-noise. In a simple magnetic implementation, the neutralizer would approach the MILCO using its forward-looking sonar and receive a binary signal (yes/no) as to magnetic/metallic content of the MILCO by comparing the boom-mounted sensor heading to the vehicle heading. In addition to providing the magnetic/metallic content estimate, the same sensor configuration could be used to locate and precisely place a neutralization vehicle over a buried mine. A magnetic/metallic anomaly guidance system would conduct a search pattern over a previously detected buried MILCO by determining where magnetic peaks occur. The neutralizer would then settle on the bottom directly over the MILCO. Currently under development by the Office of Naval Research, the Neutralizer Test Bed would make an ideal platform to mount the sensor as it has a high degree of low speed maneuverability in multiple directions. The desired sensor configuration should be capable of providing a confirmation of magnetic/metallic content at a distance of 1 meter from a MILCO (buried, proud and volume) that has a magnetic moment of 20 A·m2. The magnetic anomaly guidance system should be capable of guiding the neutralizer to within 10 cm twice the distance root mean square (2DRMS) horizontally above the magnetic centroid of an object buried 1 meter below the bottom surface. 

PHASE I: The small business will develop a concept for the magnetic/metallic detector that meets the requirements listed in the description. The company will conduct an industry search and demonstrate the feasibility of the concept in meeting Navy needs and will establish that the concept can be developed into a useful product for the Navy through software/hardware prototyping and analytical modeling. The company will provide a Phase II development plan that addresses technical risk reduction and provides performance goals and key technical milestones. The Phase I Option, if awarded, will include the initial design specifications and capabilities description to build a prototype in Phase II. 

PHASE II: Based on the Phase I results and the Phase II Statement of Work (SOW), the company will develop and deliver a prototype sensor for evaluation. The prototype will be evaluated using the Office of Naval Research (ONR) Neutralizer Test Bed in a relevant environment. The evaluation will determine the prototypes capability in meeting the performance goals defined in the Phase II development plan and the Navy requirements for the sensor. System performance will be demonstrated through prototype evaluation and modeling or analytical methods over the required range of parameters including numerous deployment cycles. Evaluation results will be used to refine the prototype into an design that will meet Navy requirements. The company will prepare a Phase III development plan to increase the TRL level and transition the technology to Navy and potential commercial use. 

PHASE III: The small business will be expected to support the Navy in transitioning the sensor technology for Navy use. The company will further refine a detection sensor compatible with mine warfare neutralizer vehicles (ONR Neutralizer Test Bed) according to the Phase III development plan for evaluation to determine its effectiveness in an operationally relevant environment. The company will support the Navy for test and validation to certify and qualify the system for Navy use. Private Sector Commercial Potential: The most significant commercial applications are for use by the oil and gas industry to detect underground pipelines and inspect underwater structures. Municipal applications include port and harbor ordnance detection and disposal. 


1. Miller, Jonathan S., et al. "Target localization techniques for vehicle-based electromagnetic induction array applications." SPIE Defense, Security, and Sensing. International Society for Optics and Photonics, 2010

2. Generalized Magnetic Gradient Contraction-Based Method for Detection, Localization and Discrimination of Underwater Mines and Unexploded Ordnance, R.F. Wiegert and J. Oeschger, MTS/IEEE OCEANS 2005 Conference Proceedings, (2005).

3. Magnetic Anomaly Guidance System for Mine Countermeasures Using Autonomous Underwater Vehicles, R.F. Wiegert, MTS/IEEE OCEANS 2003 Conference Proceedings (2003).


KEYWORDS: Magnetometer; Electromagnetic Induction; Mine Identification; Mine Counter Measures (MCM); Buried Mine Detection; Mine Neutralization 

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