Development and Testing of a Real-time Lowcost PPP and MEMS INS Loosely Coupled Georeferencing System for Small UAVs under Challenging Environments

Zhitao Lyu, Yang Jiang, Wei Ding and Yang Gao

Abstract:	With the advantage of low-cost and high precision, single frequency RTK (SFRTK) is widely used for small unmanned aerial vehicles (SUAVs) that require high precision georeferencing (position and attitude). However, the traditional SFRTK suffers from several limitations such as base station setup and short baseline length. Single frequency precise point positioning (SFPPP) is a GNSS positioning technique that could be used globally since it overcomes the dependency of a base station, enabling the SUAVs a long flight range, and maintaining decimeter-level positioning accuracy at the same time. In this paper, a real-time low-cost SFPPP and MEMS INS loosely coupled georeferencing system for SUAVs is developed and tested under open sky and GNSS challenging environment. Under GNSS challenging environment, reliable detection and removal of carrier phase cycle slips and code gross errors are major challenges in order to achieve robust GNSS positioning solution. The Doppler based phase prediction method is among the commonly used cycle slip detection methods for single frequency receiver but, it will fail when receivers output slipped Doppler. Code gross errors are usually expected to be removed using statistical testing methods, but they often fail when fewer number of satellites signals are tracked in challenging environments. In this paper, apart from a typical loosely coupled INS and GNSS integration, the IMU derived phase and code measurements are utilized for cycle slip and code gross error detection to enhance the robustness of the solution. The experimental results reveal that, the SFPPP comes to convergence within 10 minutes, hereafter the positioning accuracy reaches decimeter-level for horizontal directions, and sub-meter for vertical direction even under obstructed environments like inside a small forest. The attitude accuracy is still under improvement, which currently is 3 degrees for roll/pitch, and 10 degrees for yaw.
Published in:	Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019) September 16 - 20, 2019 Hyatt Regency Miami Miami, Florida
Pages:	2539 - 2551
Cite this article:	Lyu, Zhitao, Jiang, Yang, Ding, Wei, Gao, Yang, "Development and Testing of a Real-time Lowcost PPP and MEMS INS Loosely Coupled Georeferencing System for Small UAVs under Challenging Environments," Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019), Miami, Florida, September 2019, pp. 2539-2551. https://doi.org/10.33012/2019.17055
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