N241-046 TITLE: Micro Inertial Measurement Unit for Maritime Navigation

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Microelectronics

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 highly accurate 6-axis Inertial Measurement Unit (IMU) that is low-cost and lightweight for future U.S. Navy surface and subsurface platforms.

DESCRIPTION: The success of U.S. Navy missions depends on personnel and platforms having access to accurate and reliable position, velocity, attitude, and time information. Maritime platforms specifically need this information continuously to support safety of ship, weapons deployment, and network communications. They rely on inertial navigation systems to provide continuous position and velocity information for accurate navigation. However, current inertial navigation systems are large and expensive to build and maintain. Small-scale factor IMUs, such as Micro-Electro-Mechanical (MEMS)-based sensors, micro-Hemispherical Resonating Gyro (HRG)-based sensors, and other micro-Machined Vibrating Gyroscope (MVG)-based IMUs, offer the advantage of lower production costs through batch processing and fabrication. Some MEMS and HRG devices have also proven superior survivability to environmental shock and vibrations, which makes them ideal for military applications, given their potential for low cost and small size.

In the commercial sector, long-term accuracy has been a challenge for MEMS gyros with gyro-bias stability and Angular Random Walk (ARW) performance metrics not yet meeting navigation-grade standards, though bias-stability in MEMS accelerometers has been demonstrated to near-strategic-grade standards. Achieving the long-term accuracy desired for Naval maritime applications (going from hours to days), requires further reductions in gyro bias drift. Some factors shown to impede gyro performance include temperature drift error, mechanical imperfections, imbalances, and misalignments in the fabrication process. These can be resolved by effective vacuum packaging for environmental-resistant MEMS and/or effective temperature compensation by control circuitry, quadrature compensation, laser trimming, and circuit compensation.

Low-cost production has been a challenge in commercial HRG technology because early designs of macro-HRGs have focused on the higher performance, and higher cost, space application market. As a result, there are a limited number of HRG manufacturers, which has driven up production costs. However, new fabrication techniques, such as glassblowing and glass molding, have been developed to fabricate 3D-MEMS, or micro-HRG, devices that show the same promise of lower fabrication costs with batch production.

These existing and emerging technologies are applicable in meeting the future needs of the Navy to develop a lower cost, lightweight, and highly accurate 6-axis IMU that can be integrated into future U.S. Navy platforms. While both technology areas present challenges, fabrication and manufacturing techniques have developed significantly in MEMS wafer-scale etch processing and micro-machine fabrication techniques used to produce micro-HRGs and other MVG-based sensors in recent years.

To meet mission requirements of future deployed surface and subsurface vessels, the Navy needs a low Size, Weight, Power, and Cost (SWaP-C) 6-axis (3-axis accelerometer and 3-axis gyroscope) IMU with performance equivalent to or better than the existing Ring Laser Gyro (RLG) navigator in use in the Fleet today. Government subject matter experts will guide development for these specifications.

Achieving the desired accuracy in position, velocity, and attitude will require gyro bias stability to be demonstrated at or better than 0.005 degrees/hour (1 sigma) and ARW < 0.0005 degree/root-hour (1 sigma). Accelerometer bias stability must be demonstrated at or better than 5ug. Contributions of other error sources (that is, scale factor, misalignment, etc.) should be balanced to meet the overall error budget of the IMU. SWaP-C must meet IMU performance requirements in the range shown below:

• Size: < 5 Liter

• Weight: < 10 Kg

• Power: < 25 W

• Cost: < $100,000

Work produced in Phase II may become classified. Note: The prospective contractor(s) must be U.S. owned and operated with no foreign influence as defined by 32 U.S.C. § 2004.20 et seq., National Industrial Security Program Executive Agent and Operating Manual, unless acceptable mitigating procedures can and have been implemented and approved by the Defense Counterintelligence and Security Agency (DCSA) formerly Defense Security Service (DSS). The selected contractor must be able to acquire and maintain a secret level facility and Personnel Security Clearances. This will allow contractor personnel to perform on advanced phases of this project as set forth by DCSA and NAVSEA in order to gain access to classified information pertaining to the national defense of the United States and its allies; this will be an inherent requirement. The selected company will be required to safeguard classified material during the advanced phases of this contract IAW the National Industrial Security Program Operating Manual (NISPOM), which can be found at Title 32, Part 2004.20 of the Code of Federal Regulations. Reference: National Industrial Security Program Executive Agent and Operating Manual (NISP), 32 U.S.C. § 2004.20 et seq. (1993). https://www.ecfr.gov/current/title-32/subtitle-B/chapter-XX/part-2004

PHASE I: Develop a concept that characterizes inertial measurement sensors that meet the target metrics in the Description. Establish feasibility of an approach through analysis, modeling, and simulation to show the concept will meet the required parameters in the Description. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.

PHASE II: Design and deliver a prototype of the system described in Phase I. The prototype will undergo an independent evaluation at a government provided facility based on its ability to satisfy the parameters in the Description and its functionality in a maritime environment.

NOTE: It is probable that the work under this effort will be classified under Phase II (see Description section for details).

PHASE III DUAL USE APPLICATIONS: Assist the Navy in transitioning the technology to Navy use. The final product will be a 6-axis inertial measurement unit and will be tested on a maritime platform to demonstrate performance. Ultimately, it will be validated, tested, qualified, and certified for Navy use.

The technology will be highly valuable in any at-sea situations where GPS is not always available and high accuracy is a requirement.

REFERENCES:

1. "IEEE Standard for Inertial Systems Terminology." IEEE Std. 1559-2009, vol., no., pp.1-40, 26 Aug. 2009. doi: 10.1109/IEEESTD.2009.5226540 https://ieeexplore.ieee.org/document/5226540
2. El-Sheimy, N. and Youssel, A., "Inertial Sensors Technology for Navigation Applications: State of the Art and Future Trends, Satellite Navigation,1:2 Dec. 2020. https://satellite-navigation.pringeropen.com/articles/10.1186/s43020-019-0001-5
3. Zotov, S. et. al. "Compact In-Run Navigation Grade IMU Based on Quartz MEMS." IEEE, 2020. https://ieeexplore.ieee.org/document/9109851
4. Johnson, B. et. al. "Development of a Navigation-Grade MEMS IMU." IEEE, 2021. https://ieeexplore.ieee.org/abstract/document/9430466
5. Meyer, A.D.; Rozelle, D.M.; Trusov, A.A. and Sakaida, D.K. "milli-HRG Inertial Sensor Assembly – A Reality.," IEEE, 2018. https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8373359

KEYWORDS: Inertial Navigation System; Micro-Electro-Mechanical; Hemispherical Resonating Gyroscopes; Inertial Measurement Unit; Micro-machined Vibrating Gyroscope; Navigation

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