时间：2018年12月6日周四下午1:30
地点：光华楼东主楼1101
演讲人：Prof.Wayne Scales, Virginia Tech

联系人：付海洋

ABSTRACT: This presentation will provide a broad overview of the remote sensing research and education efforts at Virginia Tech. Afterwards, some detail will be provided on one specific agenda which is the development of a capability to use small and Cube satellites for monitoring ionospheric structures using GNSS navigation signals. GNSS-based satellite formation flight in Low Earth Orbit (LEO) opens new doors for ionospheric remote sensing. This study presents the newly developed Virginia Tech Formation Flying Testbed (VTFFTB), a multi-constellation GNSS-based hardware-in-the-loop (HIL) simulation testbed for satellite formation flight, and demonstrates the application of VTFFTB to ionospheric remote sensing technique development and mission designs. The current VTFFTB comprises GPS & Galileo RF hardware signal simulators, multi-constellation multi-frequency GNSS receivers, a navigation & control system, an ionospheric remote sensing system, and a Systems Tool Kit (STK) visualization system. A GNSS receiver was utilized to track a pair of satellites under the simulated scenario that include customized ionospheric phenomena. Based on the carrier-phase differential GPS technique, an extended Kalman filter (EKF) was implemented in the navigation & control system to estimate the relative state between the chief and deputy satellites in real time. In every time step, a flight controller is applied to maneuver the deputy to the targeted state using the current relative state, which provides the feedback for the closed-loop simulation. A reference scenario consisting of two LEO satellites was simulated and benchmarked against reference simulation results to validate the formation flight simulation capabilities. The role of the ionospheric remote sensing system is to process on-board GNSS data and generate Total Electron Content (TEC) and scintillation measurements from multiple constellations. A special scenario of formation flying with two satellites was designed and simulated on the VTFFTB to probe a customized Equatorial Spread F region that includes a plasma bubble. This study demonstrates that by measuring the space-based TEC and amplitude scintillation index S4, GNSS-based spacecraft formation flight can probe the localized vertical electron density and investigate the scale and structure of ionospheric irregularities. Analyses reveal the advantages of using both GPS and Galileo constellations to improve navigation performance and remote sensing capability. The VTFFTB can support design of future ionospheric missions and prospective applications will be discussed.

Bio: Wayne Scales received the Ph.D. degree in Electrical Engineering and Applied Physics from Cornell University, Ithaca, NY, USA. He was awarded the American Society of Engineering Education (ASEE) Postdoctoral Fellowship to pursue research at the United States Naval Research Laboratory Space Plasma Physics Branch in Washington, DC. He is the professor of Bradley department of Electrical and Computer Engineering, J. Byron Maupin Professor of Engineering and affiliate professor of Aerospace and Ocean Engineering at Virginia Tech. He is also the founding Director of the Center for Space Science and Engineering Research at Virginia Tech and co-director of interdisciplinary graduate education program in remote sensing. He also serves as Special Assistant to the Dean of Engineering. He currently serves as member-at-large of the United States National Committee of URSI and the Issues and Program Committee of the Universities Space Research Association (USRA). He has published more than 100 journal papers and obtained several education awards at Virginia Tech.