Novel Diagnostic Methods for At-Sea Testing of Inertial Navigation System Avionics
Navy SBIR 2019.1 - Topic N191-005
NAVAIR - Ms. Donna Attick -
Opens: January 8, 2019 - Closes: February 6, 2019 (8:00 PM ET)


TITLE: Novel Diagnostic Methods for At-Sea Testing of Inertial Navigation System Avionics




OBJECTIVE: Develop new diagnostic methods for Embedded Global Positioning/Inertial Navigation System (EGI/INS) and Inertial Measurement Unit (IMU) avionics that minimize support equipment footprint and complexity, while overcoming challenges of at-sea testing, to perform at or above desired fault detection/fault isolation rates.

DESCRIPTION: At-sea tests of EGI/INS and IMU avionics (e.g., AN/ASN-139 CAINS (Carrier Aircraft Inertial Navigation System) II EGI, ASQ-228 ATFLIR (Advanced Targeting Forward Looking Infrared) IMU, NGC (Northrop Grumman Corporation) LN-200) pose a unique challenge in the support equipment community. The units under test (UUTs) perform inertial sensing and geolocation functions, yet their function must be verified in an environment subject to ship motion and without access to satellite reception.

Current and proposed methods for at-sea tests of EGI/IMU present several challenges:
- High costs of sustainment for inertial reference units (IRU) equipment (incurred cost of $1.33M for 14 IRU repairs over past seven years)
- Large footprint of rate table equipment (up to 40”x40” footprint and 500-pound weight) in space-limited workshops
- Numerous fiber optic interfaces requiring additional troubleshooting and periodic maintenance
- Long test performance times that may exceed the Navy’s objective of 60 minutes for verification of a unit under test

An innovative solution is sought to replace the Navy’s Inertial Device Test Set (IDTS), a test equipment product used to diagnose and verify the operation of EGI avionics. The Navy’s IDTS currently performs the following functional tests: Alignment; True Heading; Pitch; Roll; Velocity; Latitude; Longitude; Altitude; and Navigation Drift.

The above tests are provided as a reference. In the process of developing new test methodology, some, all, or none of these tests may be utilized. The end goal for an innovative solution should be to improve upon the challenge factors listed earlier, while meeting the Navy’s requirements for diagnostic accuracy:

1) Percent Correct Detection (PCD):
Definition: [(Number of correct detections * 100)/Total number of confirmed faults]
Objective: 85%
Threshold: 70%

2) Percent Correct Fault Isolation (PCFI):
Definition: [(Number of correct fault isolations * 100)/Total number of correct detections]
 95% (for ambiguity group of <= 3  Shop Replaceable Assembly (SRAs))
 93% (for ambiguity group of <= 2 SRAs)
 90% (for ambiguity group of 1 SRA)
 70% (for ambiguity group of <= 3 SRAs)
 68% (for ambiguity group of <= 2 SRAs)
 65% (for ambiguity group of 1 SRA)

Solution must be able to achieve such diagnostic coverage that INS avionics could be deemed "Ready for Issue" (RFI) following successful test. The above diagnostic accuracy requirements are currently met by the Navy's IDTS, in conjunction with the Consolidated Automated Support System (CASS) family of testers. Solutions may also operate in conjunction with CASS, but are not limited to this design approach.

PHASE I: Determine EGI/IMU failure modes and test requirements utilizing past IDTS requirements analysis documentation and UUT test strategy reports, which will be made available to Phase I awardees. Develop a proof of concept for diagnostic techniques and perform a feasibility demonstration of test methods on EGI/INS and IMU components and/or sub-assemblies. Define an initial concept for integration method with CASS, if applicable to design approach. The Phase I effort will include prototype plans to be developed under Phase II.

PHASE II: Develop prototype test equipment capable of performing test method validation on full EGI/INS and IMU avionics assemblies. If pertinent to design approach, demonstrate integration with a CASS family tester at Joint Base McGuire Dix Lakehurst, NJ. (Note: Access to CASS equipment at Navy facility in support of SBIR activity will have no associated cost beyond contractor’s own travel expenses.) Develop concept definition for packaging and mechanical design, accounting for environmental and electromagnetic effects requirements in Navy I-level afloat maintenance shops [Ref 5] (MIL-STD-461 for Navy surface ships, below deck equipment, using test methods CE101, CE102, CS101, CS106, CS114, CS116, RE101, RE102, RS101, and RS103).

PHASE III DUAL USE APPLICATIONS: Transition program for use in Navy I-level maintenance, integrating with all variants of the CASS Family of Testers, followed by regression testing of all existing IDTS Test Program Sets (TPS). TPS code comprises the test instructions executed on CASS to direct the test and measurement instrumentation. During technology transition, any new inertial device test technology must demonstrate ability to accept CASS commands, as generated by current Navy TPS code. Upon completion, the new SBIR-developed technology would be fielded in place of the existing IDTS CASS ancillary equipment.

EGIs and IMUs found within Navy air platform weapon systems are often COTS avionics used in other systems across DoD and commercial aviation (e.g., commercial passenger airlines) and transportation industries (e.g., commercial shipping, trucking, and air freight transportation). EGI/INS and IMU equipment is commonly used to aid navigation on ships, aircraft, submarines, guided missiles, and spacecraft. Novel test techniques for Navy EGI/IMU avionics may enable improvements in EGI/IMU maintenance across the range of commercial aviation and transportation industries that rely on similar equipment.


1. Inertial Device Test Set (IDTS) RFI for second generation system, Solicitation Number: N68335-17-R-0033.

2. Sole source justification document for solicitation leading to acquisition of Navy's current EGI test equipment, Inertial Device Test Set (IDTS).

3. Smalling, K. and Eure, K. “A Short Tutorial on Inertial Navigation System and Global Positioning System Integration.” NASA Langley Research Center: Hampton, VA, 2015.

4. Renfroe, P.B. et al. “Test and Evaluation of the Rockwell Collins GNP-10 for the Precision Kill and Targeting (PKAT) Missile System.” IEEE 2000, Position Location and Navigation Symposium: San Diego, CA, USA, 2000, pp. 488-493.

5. MIL-STD-461G Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment.

KEYWORDS: Support Equipment; Avionics Test; Automatic Test Equipment; Automated Test Systems; Inertial Test; GPS Test


Matt Morgan





Gregory Zucaro





These Navy Topics are part of the overall DoD 2019.1 SBIR BAA. The DoD issued its 2019.1 BAA SBIR pre-release on November 28, 2018, which opens to receive proposals on January 8, 2019, and closes February 6, 2019 at 8:00 PM ET.

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