MEMS and FOG Technologies for Tactical and Navigation Grade Inertial Sensors—Recent Improvements and Comparison

Abstract

In the following paper, we present an industry perspective of inertial sensors for navigation purposes driven by applications and customer needs. Microelectromechanical system (MEMS) inertial sensors have revolutionized consumer, automotive, and industrial applications and they have started to fulfill the high end tactical grade performance requirements of hybrid navigation systems on a series production scale. The Fiber Optic Gyroscope (FOG) technology, on the other hand, is further pushed into the near navigation grade performance region and beyond. Each technology has its special pros and cons making it more or less suitable for specific applications. In our overview paper, we present latest improvements at NG LITEF in tactical and navigation grade MEMS accelerometers, MEMS gyroscopes, and Fiber Optic Gyroscopes, based on our long-term experience in the field. We demonstrate how accelerometer performance has improved by switching from wet etching to deep reactive ion etching (DRIE) technology. For MEMS gyroscopes, we show that better than 1°/h series production devices are within reach, and for FOGs we present how limitations in noise performance were overcome by signal processing. The paper also intends a comparison of the different technologies, emphasizing suitability for different navigation applications, thus providing guidance to system engineers.

Key Regional Comparison COOMET.AUV.A-K5. Analysis of the Results

“…Accelerometer specifications for inertial guidance of an autonomous vehicles will be the strictest compared to the other applications discussed above, since in the event that a GPS signal is lost the position of the vehicle must be determined by the inertial guidance system over a period of time that might span tens of minutes. The current designs for capacitive MEMS-based accelerometers and gyroscopes may not ever meet requirements for fully autonomous driving and may have to move towards optical based systems [2,3] instead of today's capacitive based systems.…”

Efficient Modulation and Processing Method for Closed-Loop Fiber Optic Gyroscope with Piezoelectric Modulator

“…Currently, the highest-grade I-FOGs using polarization-maintaining (PM) optical fiber and an integrated electro-optic modulator have surpassed the performance of RLGs, achieving a stability better than 0.001∘/h [5]. In applications such as AHRSs or gyrocompassing, a stability between 0.01–5∘/h is sufficient, and more attention is paid to cost reduction [3,6]. Thus, multiple solutions replacing PM fiber with ordinary single-mode (SM) fiber were proposed [7,8,9,10,11] and adopted for commercial usage by some of the leading manufacturers [1,12,13].…”

Self-Alignment MEMS IMU Method Based on the Rotation Modulation Technique on a Swing Base

“…Inertial navigation systems (INSs) based on high precision inertial gyros tend to be bulky and costly, which limits their application. With the technical development of micro-electro-mechanical-systems (MEMSs), MEMS-based inertial sensors have achieved success in commercial fields such as pedestrian navigation, robotics, unmanned aerial vehicles (UAVs), and autonomous underwater vehicles (AUVs) because of their many attractive features such as being low cost, small, and lightweight, with lower power consumption [ 1 , 2 ]. However, current MEMS inertial sensors have lower accuracy than high end inertial measurement units (IMUs).…”