Precision Navigation for UAVs, Mini-Munitions, and Handhelds through Application of Low Cost Accurate MEMS IMU/INS Technology

Martin Tanenhaus, Dean Carhoun and Alex Holland

Abstract:	GPS has previously been integrated with mobile PDA's and/or with Inertial Measurement Units (IMUs). However, to date, no low-cost, low-power, miniature (i.e., less than 2 in.³) IMU/INS has been integrated into smart munitions, electronics, handheld GPS units or miniaturized cooperative low cost interceptors to create a miniature G hardened multi-functional module. Several DoD contractors are evaluating the JayMart Sensors low cost miniature IMU/INS module for smart munitions, mini-missile and micro-UAV weapons. A commercial company will soon link the module to a network of mobile PDA's enabled with GPS to provide location-based coverage indoors for emergency workers and DoD is scheduled to gun launch the module to test its ruggedness later this year. The IMU/INS module may be integrated directly with GPS or linked to external military and commercial GPS devices as they evolve. Such integration is highly desirable as GPS suffers from several well known accuracy and signal outage issues that preclude or make its use problematical under many operational conditions. Lack of reliable location information at critical times can result in serious operational issues, some of which include: reduced aim-point effectiveness, increased danger of friendly fire accidents, and danger to workers in raging fire situations. The achievement of tactical grade performance at significantly lower cost in a rugged small module is just the first step in pursuit of navigation and guidance systems to meet fast growing market demands. Although Micro-Electro-Mechanical Systems (MEMS) are an enabling technology, individual COTS devices do not achieve tactical grade levels of performance. Instead, the fusion of MEMS devices combined with signal processing electronics all packaged in a small module have made it possible to demonstrate significant improvements in measuring angular rate, angular velocity and acceleration while minimizing temperature drift in less than a 2 in³ package. Arrays of randomly selected MEMS sensors can minimize large bias instability, reduce noise found in individual devices, and improve overall accuracy previously reported in MEMS-based IMU's. The introduction of individual sensor temperature and null compensation will optimize gyro performance, especially during the short time between first power start and internal temperature stabilization. Furthermore, we are exploring the selection of devices using detailed factory provided data for each device to optimize the array of devices assigned to each axis, as well as coupling with GPS and auxiliary velocity update micro-modules that will provide additional levels of performance in the near future. This paper describes the IMU and Azimuth Sensing features and performance measurements. The results of the embedded gyro array processing and wavelet de-noising open loop outputs, including rate table test data, Allan Deviation plots that illustrate the noise reduction performance, and Allan Deviation plots that illustrate the performance of biascompensated channel outputs will be presented. Open-loop angle, velocity and position drift for bias-compensated channels that illustrate performance bounds for a closed loop Kalman Filter solution and the expected results for the extended Kalman filter to implement real-time AHRS are also discussed.
Published in:	Proceedings of IEEE/ION PLANS 2008 May 6 - 8, 2008 Hyatt Regency Hotel Monterey, CA
Pages:	244 - 252
Cite this article:	Tanenhaus, Martin, Carhoun, Dean, Holland, Alex, "Precision Navigation for UAVs, Mini-Munitions, and Handhelds through Application of Low Cost Accurate MEMS IMU/INS Technology," Proceedings of IEEE/ION PLANS 2008, Monterey, CA, May 2008, pp. 244-252. https://doi.org/10.1109/PLANS.2008.4569976
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