TECHNOLOGY AREAS: Ground/Sea Vehicles, Sensors, Battlespace

ACQUISITION PROGRAM: Oceanographer of the Navy, PMS-NSW, PMS-403, PMS-485, and PMS-495

OBJECTIVE: Design and develop a compact, light weight, low cost, non-inertial sensor capable of providing external navigation reference information for small UUVs conducting environmental and tactical reconnaissance in littorals and riverine areas. The system shall be easily integratable as a module to a number of existing underwater deployed sensors and unmanned underwater vehicles.

DESCRIPTION: For naval forces operating in riverine and coastal areas, environmental and tactical reconnaissance is an indispensable part of any operation prior to entry. With on-going advances in capabilities, growing number of unmanned platforms are expected to conduct preoperational reconnaissance missions autonomously. Compared to other unmanned vehicles, UUVs provide unique advantages of conducting reconnaissance missions in riverine and coastal environments including their ability to conduct missions covertly and to employ acoustic sensors that are not affected by water turbidity or surface waves often predominant in such environments. Full submergence in the water column, however, means that UUVs may not have ready access to GPS.

For submerged UUVs, there are navigational methods such as dead reckoning, INS, Doppler velocity log (DVL), or acoustic beacon based systems such as LBL and USBL. Among these methods, DVL has a unique capability of directly sensing the vehicle velocity relative to the seabed. It doesn�t require any pre-emplacement of beacon network, thus DVL is an ideal navigation sensor for covert underwater missions. Some of the commercial UUVs offer integrated INS/DVL navigation systems with remarkable accuracies while submerged. There are, however, some issues of integrating a DVL into a man portable UUV for conducting reconnaissance in rivers and coastal areas. For the naval forces operating from a small platform in such areas, key requirements for unmanned vehicles are small, light weight, low cost, and accurate navigation. For a small UUV, DVL integration may take up to forty percent of both the total cost and the weight of the vehicle. An innovative new concept is therefore solicited to develop an affordable, light weight, precision non-inertial underwater navigation sensor capable of providing external reference information suitable for integration into a compact UUV system. Although acoustics may to be the most robust modality for navigational measurements in turbid water, other modalities such as optics may also be considered if an innovative concept is available to alleviate the issue of optical opaqueness of riverine and littoral water. A compact UUV with a vehicle weight less than 10 lb has been viewed as ideal for riverine and littoral reconnaissance missions, therefore the alternative navigation system shall not weight more than 1 lbs with a volume nominally 30 cubic inches. The derived overall navigational accuracy shall be equivalent or better than currently available DVL based sensors, and per unit cost shall be nominally $2000.00 or less. Since the expected operating environment is littoral or riverine, the design depth shall be no more than 40 feet.

Phase I: Specific design concepts of material, hardware, and software components of the non-inertial navigation sensor to achieve the objective requirements should be proposed along with an integrated system design. Component level and system level modeling and analyses are to be conducted to justify the proposed design and system integration. The design analyses should focus on feasibility of any new proposed concept of transducer material, component, and integration for overall system performance in the riverine and coastal environments.

Phase II: A prototype will be produced and fully demonstrated in Phase II. Test and analysis will document the navigation sensor system performance with respect to the stated objectives as well as performance limitations in laboratory and in near shores and in rivers. In addition to operational performance issues, the Phase II efforts should address issues such as reliability, manufacturability, and toughness in severe environmental conditions.

Phase III: Proposer will develop an acquisition-ready alternative navigation sensor system description that meets well defined operation guidelines. Full manufacturing documentation will allow rapid production to occur with the vendor team.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Commercial production and distribution of an affordable, compact, non-inertial navigation system parallels Navy interests. The same alternative concept of the non-inertial measurement of reference environmental motion may lead to new flow velocity field measurements currently done by ADCP type sensors. Affordability and compactness of the alternative concept would attract designers of developing alternative ADCP type sensors for private sector use. Primary applications in the near-term will address environmental baselining, monitoring, and change detection seasonally and in response to incremental or episodic events. Communities, ports, and resource management entities are likely the first customers, and their requirements for affordability and size requirements will be similar to the Navy requirements.

REFERENCES:
1) The Navy Unmanned Undersea Vehicle (UUV) Master Plan, 2004: (http://www.navy.mil/navydata/technology/uuvmp.pdf)

2) Autonomous Vehicles in Support of Naval Operations: Naval Studies Board, National Academies Press, 2005: (http://www.nap.edu/catalog.php?record_id=11379)

3) J. J. Leonard, A. A. Bennett, C. M. Smith, H. J. Feder, "Autonomous Underwater Vehicle Navigation," MIT Marine Robotics Laboratory Technical Memorandum 98-1

KEYWORDS: navigation; DVL; sensor; UUV; IMU; doppler

Questions may also be submitted through DoD SBIR/STTR SITIS website.