中文摘要：

TNNS（真航向导航系统）由MS860接收机、INS及处理数据的PC／104架构的嵌入式工控机构成．针对TNNS推导了INS（惯性导航系统）的误差模型，提出了适合于TNNS的降阶扩展卡尔曼滤波算法组合GPS和INS。系统在东海作了三次海试，软件及滤波算法平台由C／C＋＋编制．海上试验表明，组合滤波后，INS的位置误差由i00m降低到40m以下；进行最优化滤波后的航向误差α由原来的0．105°减小为0．034°，纵横摇的误差也大幅减小．整个海试结果表明，在TNNS中组合GPS／INS采用的降阶扩展卡尔曼滤波算法，大幅提高了系统精度和可靠性．

英文摘要：

TNNS （True North Navigation System） consist of MS860 GPS, INS（inertial navigation system）, and a PC/104 embedded computer system for processing data An INS error model was developed for the actual TNNS. Based on the error model, a reduced-order EKF（Extended Kalman Filter） algorithm was designed for TNNS. The system tests have been conducted three times at East China Sea. TNNS software and the reduced-order EKF algorithm are programmed by C/C＋＋ codes, and executed under real-time mode in the embedded computer. The test results show that the INS position errors in north and east are reduced from more than 100 m to 40 m after correction, and the heading error o is reduced from 0.105° to 0.034° after optimal filter correction. The accuracy of roll and pitch is also increased greatly by the integration of MS860 GPS/INS. The whole tests validate the effect of the algorithm, and show that the TNNS performance is significantly improved by the reduced-order EKF.