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。这些调查的目标是提供对水下生物学，生态学，地质学，物理海洋学以及全球空气，海洋和冰的相互作用的更好理解。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进行精确的近海底海洋学调查的能力是前所未有的，然而，由于正北姿态传感器的高成本，在无人水下航行器上广泛使用精确导航技术受到限制。该项目旨在开发一种高精度、相对低成本、紧凑和低功耗的真北寻姿（航向、俯仰和滚转）传感器，并将这种新仪器纳入一个紧密集成的UUV精密多普勒导航系统。目标是开发一种成本相对较低和高精度的导航系统，使小型低成本无人潜水器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、环境评估的时间序列声学和光学测量），目前认为这些任务对于低成本无人潜水器是不切实际或不可行的。该项目将使本科生和研究生能够进行实践研究，并传播他们的研究成果。仪器设计将开源，包括机械设计、电气设计和软件算法，这些都将作为开源软件包免费提供。该项目有三个技术目标：第一、采用新型相对低成本的商用现货（COTS）惯性测量单元（伊穆斯），该惯性测量单元配备有集成的3轴光纤陀螺（FOG）角速率传感器和3-轴微机电系统（MEMS）加速度计，以及实时状态估计方法，以提供仪器相对于真北和当地重力场的航向、俯仰和横滚的准确估计。第二，发展改进的水下导航方法，采用低成本的光纤陀螺伊穆斯和底部锁定多普勒声纳。第三，在试验水池和海上用UUV进行全尺寸试验，评估这些导航方法。

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.