Development of a Low-Cost True-North Seeking Fiber Optic Gyrocompass and Integrated Doppler Navigation System for Precision Navigation of Underwater Vehicles for Ocean Science

海洋科学家开始使用无人驾驶机器人在海洋、湖泊和河口进行调查。这些调查的目的是为了更好地了解水下生物学、生态学、地质学、物理海洋学以及世界各地的空气、海洋和冰的相互作用。这些数据提高了科学家对具有重大社会意义的全球生态和气候的理解。利用无人水下航行器(UUV)进行精密近底海洋调查的能力是史无前例的，然而，真北姿态传感器的高昂成本限制了UUV精确导航技术的广泛使用。该项目旨在开发一种高精度、相对低成本、紧凑、低功耗的正北寻轨姿态(航向、俯仰和横摇)传感器，并将这一新仪器集成到UUV的紧密集成的精密多普勒导航系统中。其目标是开发一种相对低成本和高精度的导航系统，使小型低成本UUV能够执行需要高精度导航的科学任务(例如，高精度水文测量、用于环境评估的时间序列声学和光学测量)，这些任务目前被认为与低成本UUV不切实际或不可行。该项目将使本科生和研究生能够亲身实践研究，并传播他们的研究成果。这个项目有三个技术目标：第一，采用成本相对较低的新型商用(COTS)惯性测量单元(IMU)，配备集成的三轴光纤陀螺(FOG)角速率传感器和三轴微机电系统(MEMS)加速计，以及实时状态估计方法，以提供准确的航向、俯仰、以及仪器相对于真北方向和局部重力场的滚动。其次，开发采用低成本光纤陀螺IMU和底锁多普勒声纳的改进水下导航方法。第三，在水箱和海上使用UUV进行全面的实验试验，对这些导航方法进行评估。

Ocean scientists are beginning to employ unmanned robotic vehicles to conduct surveys in oceans, lakes, and estuaries. The goal of these surveys is to provide a better understanding of underwater biology, ecology, geology, physical oceanography, and the interaction of air, sea, and ice worldwide. These data improve scientists' understanding of global ecology and climate that are of great societal importance. Having the ability to conduct precision near-bottom oceanographic surveys with unmanned underwater vehicles (UUVs) is unprecedented, yet the widespread use of precision navigation techniques on UUVs is limited by the high cost of true-North attitude sensors. This project seeks to develop a high-accuracy comparatively low-cost, compact, and low-power true-North seeking attitude (heading, pitch, and roll) sensor, and to incorporate this new instrument into a tightly integrated precision Doppler navigation system for UUVs. The goal is to develop a comparatively low-cost and high-accuracy navigation system to enable small low-cost UUVs to perform science missions requiring high-precision navigation (e.g. high precision hydrographic survey, time-series acoustic and optical survey for environmental assessment) that are presently considered impractical or infeasible with low-cost UUVs. This project will enable hands-on research by undergraduate and graduate students and dissemination of their research results. The instrument design will be made open-source, including mechanical designs, and electrical designs, and software algorithms that will be freely available as open-source software packages.This project has three technical goals: First, employ the new class of relatively low-cost commercially-available-off-the-shelf (COTS) inertial measurement units (IMUs) equipped with integrated 3-axis fiber-optic gyro (FOG) angular-rate sensors and 3-axis micro-electromechanical systems (MEMS) accelerometers, together with real-time state estimation methods to provide accurate estimation of the heading, pitch, and roll of the instrument relative to true-North and the local gravity field. Second, develop improved underwater navigation methods employing low-cost FOG IMUs and bottom-lock Doppler sonars. Third, evaluate these navigation methods in full-scale experimental trials with UUVs in a test-tank and at sea.