J. Korean GNSS Society 1(1), 51-57 (2012) http://dx.doi.org/10.11003/JKGS.2012.1.1.051 published irst issue Autumn 2012 Copyright © The Korean GNSS Society http://www.gnss.or.kr plSSN: 2287-7398 J KGS Journal of the Korean GNSS Society 1. INTRODUCTION The NAVSTAR Global Positioning System (GPS) is a satellite navigation system that started to be developed by the U.S. Department of Defense in 1973 for the purpose of overcoming the limitations of local radio navigation system like OMEGA, LORAN, TACAN, etc. (National 1995) and is utilized as the representative Global Navigation Satellite System (GNSS) until now since the Fully Operational Capability has been declared in 1994 (Kaplan & Hegarty 2006). he GPS originally used for military purposes is now not only used as a major navigation system for aircraft, ships, and land vehicles but also takes its place in a major infra system for almost all sectors including the mobile phones. Although the GPS receiver has the advantage that it can provide an accurate and stable position, velocity and time information of users regardless of meteorological conditions at anytime and anywhere, it has the disadvantage that it cannot provide the navigation results when the signals are Design of an Error Model for Performance Enhancement of MEMS IMU-Based GPS/INS Integrated Navigation Systems Moonsuk Koo 1 , Sang Heon Oh 2 , Dong-Hwan Hwang 1† 1 A Department of Electronics Engineering, Chungnam National University, Daejeon 305-764, Korea 2 Hanyang Navicom Co., Ltd., Gwanpyeong-dong 713, Yuseong-gu, Daejeon 305-509, Korea ABSTRACT In this paper, design of an error model is presented in which the bias characteristic of the MEMS IMU is taken into consideration for performance enhancement of the MEMS IMU-based GPS/INS integrated navigation system. The drift bias of the MEMS IMU is modeled as a 1st-order Gauss-Markov (GM) process, and the autocorrelation function is obtained from the collected IMU data, and the correlation time is estimated from this. Prior to obtaining the autocorrelation function, the noise of IMU data is eliminated based on wavelet. As a result of simulation, it is represented that the parameters of error model can be estimated correctly only when a proper denoising is performed according to dynamic behavior of drift bias, and that the integrated navigation system based on error model, in which the drift bias is considered, provides more correct navigation performance compared to the integrated navigation system based on error model in which the drift bias is not considered. Keywords: MEMS IMU, error model, denoising, autocorrelation, bias stability blocked by buildings in downtown, or there is an intentional or unintentional radio jamming. In addition, the generic GPS receiver cannot provide attitude information, and because the output rate of navigation information is low, it is difficult to be used independently for vehicles with high dynamics like aircraft or guided weapons. In order to supplement these disadvantages of GPS, lots of researches on integrated navigation system in which the GPS and the Inertial Navigation System (INS) are combined have been performed (Bezick et al. 2010). he GPS/INS integrated navigation system calculates the navigation information from output of accelerometer and gyro of the IMU, and corrects the INS navigation errors with the aid of GPS navigation results in the integrated Kalman filter which is based on the error model of the INS. The INS navigation errors are caused by bias, misalignment, scale factor, output noise, etc. included in output of the IMU (Titterton & Weston 2004). In order to correctly estimate the INS navigation errors, the errors should be included in the error model of the integration Kalman ilter (Maybeck 1979, Zarchan & Musoff 2005). Recently, as the semiconductor technology develops, a low-price and high- performance Micro-Elecro Mechanical System (MEMS)- based IMUs are widely used. In order to obtain the high- performance navigation results, it is required to take into Received Sep 28, 2012 Revised Oct 23, 2012 Accepted Oct 26, 2012 † Corresponding Author E-mail: dhhwang@cnu.ac.kr Tel: +82-42-821-5670 Fax: +82-42-823-5436