DON26BZ01-NV026 TITLE: Passive-Active Combo System for Unmanned Characterization of Littoral Environments

OUSW (R&E) CRITICAL TECHNOLOGY AREA(S): Contested Logistics Technologies (LOG)

COMPONENT TECHNOLOGY PRIORITY AREA(S): Integrated Sensing and Cyber;Sustainment

PROJECTED CMMC LEVEL REQUIREMENT: Level 2 (Self)

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a lightweight, integrated passive imaging and LiDAR system, deployable on an unmanned aerial platform for target detection, feature characterization, and bathymetry retrieval in littoral environments. The system should be light enough for deployment from a Group 2 (max. gross takeoff weight: 21 – 55 lbs.) unmanned aerial vehicle (UAV).

DESCRIPTION: Achieving and maintaining maritime dominance in the coastal battlespace requires the Navy and Marine Corps to have superior situational awareness. A key component of this dominance is the ability to rapidly characterize shallow, nearshore environments [Ref 1] in real-time using agile, unmanned aerial platforms. To this end, a system is needed that provides (1) bathymetry retrieval; (2) detection and discrimination of underwater targets; and (3) characterization of the land-ocean interface (i.e., surface type, topography, and shallow-water bathymetry).

Current UAV-based shallow water and littoral zone characterization relies on either (1) passive imagers alone or (2) bathymetric LiDAR systems deployed on larger airborne platforms or in separate missions. While passive imagers effectively characterize surface features, bathymetric LiDAR is necessary for bathymetry retrieval and underwater target detection. Simultaneous deployment of both a high-performance passive imager and a bathymetric LiDAR on a Group 2 UAV is challenging due to payload weight limitations. Systems that attempt this combination often compromise sensor performance or utilize topographic LiDAR [Ref 2], which uses near-infrared wavelengths unsuitable for bathymetry retrieval.

One potential solution is a system that can accommodate a passive imager and a dual-wavelength LiDAR that operates at two wavelengths – one where light penetrates deep into the water column and another with very little to no penetration into the water column – which can be used to effectively discriminate between LiDAR returns from the water surface and the substrate. The heaviest part of a topo-bathy LiDAR is the scanning component. A non-scanning, nadir-viewing LiDAR system would be light enough for simultaneous deployment on a Group 2 UAV. The passive imager could be hyperspectral or multispectral but should provide sufficient spectral information to spectrally characterize the water column and the land-ocean interface and discriminate underwater objects and features. Single nadir lines of LiDAR returns from adjacent flight lines could be mapped onto corresponding spatially explicit imaging data to build three-dimensional profiles of bathymetry. Coincidental LiDAR and imaging data could also be used to train a regression-based machine learning (ML) model to estimate depths from the imaging data, similar to previous empirical approaches [Ref 3].

The system should provide rapid onboard processing of passive spectral and LiDAR data and real-time downlink of preliminary output to a ground station. The output should include a true-color composite of the target area, a topo-bathy map, a target detection map (showing locations of targets of interest, which could be new objects or objects with known properties pre-programmed into the system), and a terrain characterization map (showing information on the terrain type, concentration of optically significant constituents in the water column, and bottom type). Performers may use simple or sophistical techniques to retrieve information from spectral imaging data, such as simple band-ratio algorithms, spectral inversion based on radiative transfer modeling, spectral derivatives, or ML techniques. The system should provide the above information for coastal waters up to 20 meters depth in moderately turbid waters (diffuse attenuation coefficient at 490 nm, Kd(490) ˜ 2-4 m-1). Note: SBIR funds may be used to purchase a Group 2 UAV to serve as a platform for the imager + LiDAR combo system.

PHASE I: Develop a preliminary observing system simulation experiment to simulate optical and spectral models for the combined passive imaging and LiDAR system. Perform sensitivity analysis of system performance for a range of design configurations under varying conditions of turbidity and optical complexity of shallow water environments. Conduct a feasibility study for the proposed system. Provide a report of the feasibility study and an initial layout of the proposed system design.

PHASE II: Develop the prototype based on optimal design configurations determined from the Phase I feasibility study. Finalize the approach for exploiting spectral information from the passive imager and combining spectral information with LiDAR returns for retrieval of three-dimensional bathymetry and characterization of the water column and the nearshore terrain. Limited demonstrations of the prototype are also required.

PHASE III DUAL USE APPLICATIONS: Upon successful demonstration of the prototype in Phase II, the system shall be flight-tested, developed into a commercial product against existing requirements of the Navy’s Airborne Littoral Mine Detection System (ALMDS) and the Marine Corps’ Standoff Explosive Detection System for operational coastal characterization and mine detection for transition consideration.

Blue-green LiDAR serves environmental monitoring, underwater mapping, and marine ecology purposes. With effective and specific processing, data acquired from this technology can be tailored for either commercial or military applications.

REFERENCES:

1. Ashphaq, M.; Srivastava, P. K. and Mitra, D. "Review of near-shore satellite derived bathymetry: Classification and account of five decades of coastal bathymetry research." Journal of Ocean Engineering and Science, 6(4), 2021, pp. 340-359. ISSN 2468-0133. https://doi.org/10.1016/j.joes.2021.02.006"
2. Headwall Nano HP™ Data Sheet, 2024." Headwall Photonic. https://headwallphotonics.sharefile.com/share/view/s7eb68d3ad9b242518822c77e5058b57b
3. König, M. and Oppelt, N. "A linear model to derive melt pond depth on Arctic sea ice from hyperspectral data." The Cryosphere, 14, 2020, pp. 2567-2579. https://doi.org/10.5194/tc-14-2567-2020

KEYWORDS: Passive + active imaging system; topo-bathy LiDAR; mine detection; coastal characterization; unmanned aerial systems; nearshore bathymetry

TPOC 1
Joong Kim
joong.h.kim4.civ@us.navy.mil

TPOC 2
Wesley Moses
wesley.j.moses.civ@us.navy.mil