To Navigate the Autonomous Underwater Vehicle (AUV) accurately is one of the most important aspects in AUV's study. The paper presents the basic composition and integration method of the AUV's navigation system using Extended Kalman Filtering (EKF) technique. In the specified application, GPS receiver, Strapdown INS and Doppler Velocity Log (DVL) are mounted aboard on the test vessel. The 3-day experiment was carried out in Songhua Lake, nearby Harbin City. The test results show that the system is able to achieve high precision, which is one meter approximately, with GPS and DVL working properly. Without GPS augmentation, which is the usual configuration for AUV application, accurate positioning and navigating results are still available, provided that the DVL satisfies its working requirements. Under this situation, a 3-meter precision could be reached. Besides the theoretical and experimental analysis of the integrated navigation system, the alignment technique in swing base is also discussed in detail.

Rhere exists a slope drifrion an integra gyro when it is used as an azimush gyro, which may cause serious heading and posirion erross in: be Inertial Navigation System (INS). Thereby, it is necessary to estimate and colmpensate ir. This paper describes its cause and characteristes. A methed of esing the output of INS after BBA CALTHRASION to estimase it and constant drift is discussed in detail. In addition. some issues needed to nore in the practical operation are provided too. Software-simniztion and practical experiment both show the valid-ty of this method.

Transport-related environmental problems continue to constitute a major challenge to policy makers at all levels. A key feature of these problems is that they arise from the interaction of human behavioral systems and physical systems. Thus, to improve our understanding of environmental and health problems associated with vehicle emissions it is necessary to combine data on both travel and traffic behavior with environmental data linked to the corresponding spatial and temporal variables. There are currently no such databases available. A new low-cost real-time device is currently under development utilizing the latest developments in environmental monitoring, navigation, communications, data mining and warehousing to capture spatio-temporally referenced data on vehicle and driver performance and the level of emissions and concentrations. Because of the need to acquire data in all environments, there are potential limitations in using a global satellite navigation system such as GPS to determine the spatial and temporal data in built-up areas. Therefore, an augmentation strategy involving differential GPS and new low-cost dead reckoning sensors utilizing micro-electromechanical systems technology has been explored. This paper presents a high-level description of the real-time vehicle performance and emissions monitoring system, and details the results of a study carried out to characterize the performance of stand-alone and augmented GPS, and assess whether the required navigation performance is achievable. The study characterized the performance of different types of stand-alone GPS receivers and GPS augmented with differential infrastructure and low-cost dead reckoning sensors. The performance indicators used were satellite visibility, coverage, accuracy and integrity. The results highlight the weaknesses and differences in performance, depending on the type of GPS receiver used and shows that, unlike GPS alone, an integrated system employing GPS and low-cost dead reckoning sensors is capable of meeting the required navigation performance in built-up areas. Furthermore, no significant difference in accuracy between standalone GPS and differential GPS has been seen.