Integrated INS/GPS/PLS For Navigation System

Inertial Navigation System (INS) has been recognized as a well-suited tool for self-contained navigation. However, the accuracy of INS navigation is reduced rather fast with time. INS is hard to satisfy the navigation accuracy for long time. Global Positioning System (GPS) is a three-dimensional real-time global navigation system with high accuracy, but GPS signal is easy to be interrupted. This is a major limitation to GPS applications. GPS/INS integrated navigation system can overcome disadvantages of each systems and provides more accurate navigation results than INS and GPS alone. However, GPS can't provide enough and stable positioning accuracy to correct INS errors in city canyon. Moreover, GPS can't be employed under ground such as subway. Pseudolite (PLS) is an effective approach to solve these problems. PLS is utilized to increase the number of visible satellites and improve their geometric distribution. Thus, the positioning accuracy and reliability are improved.The method of INS/GPS/PLS integrated navigation system is explored in this work. The advantages and disadvantages of each navigation systems are analyzed, and the state error models and observation equations of integrated system are established. Then the fuzzy logic rule is developed and fuzzy logic Kalman filter equations are presented. The experimental results show that the performance of the fuzzy logic Kalman filter is better than that of standard Kalman filter. Finally, GPS/IMU integrated system is developed. The experimental results show that the accuracy of pitch angle and roll angle is 0.06 deg, respectively, and positioning accuracy is 1.8 m in East and 0.9 m in North.INS/GPS/PLS integrated navigation system is designed in this work. The basic concept and navigation message format of PLS is given. The key technique of PLS is analyzed. Then the framework and flowchart of INS /GPS/PLS integrated navigation system are presented. The experimental results show that the accuracy of GPS/PLS integrated systems is higher than that of GPS alone.