GPS/INS

About: GPS/INS is a research topic. Over the lifetime, 3554 publications have been published within this topic receiving 62784 citations.

Sensor fusion for navigation of an autonomous unmanned aerial vehicle

Abstract: This paper presents the position and velocity determination by using INS and GPS. The measurement results from INS and GPS sensors are fused by using Kalman filter. Dilution of Precision (DOP) technique is used to select a combination of satellites to be used as measurement data. Two implementations of Kalman filter, feedforward and feedback are used. The experiment shows that the selection of the satellites affects the measurements. The methodology and experiments presented in this paper has been developed and tested for the autonomous Unmanned Aerial Vehicle (UAV).

Using inertial sensors of iPhone 4 for car navigation

Abstract: Smart phones start to equip with MEMS tri-axis accelerometer (i.e. G-sensor) and tri-axis gyroscope chips in recent years for user interface (UI) and game playing purposes. These two sensors actually compose a complete IMU and might be qualified as an INS to aid the GPS positioning of the phones, i.e. a GPS/INS integrated navigation system can be implemented. This paper explores the idea of using the inertial sensors in iPhone 4 from Apple Inc. to make GPS/INS integration for car navigation. A loosely-coupled integrated navigation algorithm with 15-states Kalman filter was used to fuse the data from the GPS and the MEMS inertial sensors. The results of road tests have shown that the MEMS sensors can bridge the GPS position gaps effectively, and can provide attitude estimation at degree level accuracy. The non-holonomic constraint can improve the navigation performance significantly, including both the position and heading. The attitude accuracy can reach the level of 1.4 degrees for tilt, and 2.0 degrees for heading. During the GPS signal outages (e.g. tunnel cases), the position drifts of the MEMS INS are at the level of 30 meters after 30 seconds, with the non-holonomic constraint. Results of this paper proved that the inertial sensors of iPhone 4 can be used for car navigation purpose. They can provide enhanced positioning capability and decent attitude estimation for various applications.

Tightly coupled integration of ionosphere-constrained precise point positioning and inertial navigation systems.

Abstract: The continuity and reliability of precise GNSS positioning can be seriously limited by severe user observation environments. The Inertial Navigation System (INS) can overcome such drawbacks, but its performance is clearly restricted by INS sensor errors over time. Accordingly, the tightly coupled integration of GPS and INS can overcome the disadvantages of each individual system and together form a new navigation system with a higher accuracy, reliability and availability. Recently, ionosphere-constrained (IC) precise point positioning (PPP) utilizing raw GPS observations was proven able to improve both the convergence and positioning accuracy of the conventional PPP using ionosphere-free combined observations (LC-PPP). In this paper, a new mode of tightly coupled integration, in which the IC-PPP instead of LC-PPP is employed, is implemented to further improve the performance of the coupled system. We present the detailed mathematical model and the related algorithm of the new integration of IC-PPP and INS. To evaluate the performance of the new tightly coupled integration, data of both airborne and vehicle experiments with a geodetic GPS receiver and tactical grade inertial measurement unit are processed and the results are analyzed. The statistics show that the new approach can further improve the positioning accuracy compared with both IC-PPP and the tightly coupled integration of the conventional PPP and INS.

Method and apparatus for calibration of a GPS receiver

Abstract: The methods and apparatus of the present invention provides for determining accurate positions using a global positioning satellite system (GPS), either the United States Navstar or Russian Glonass, without the use of radio broadcast differential corrections. The method contemplates that selective availability (S/A) is either disabled or satellites with S/A active can be identified and not used. In one method, a GPS receiver is positioned at a reference location with a known position. The apparent position determined by the GPS receiver is then compared to the known position to determine an error correction. Preferably, the error correction is made to each satellite's pseudorange as a timing or range correction. When the GPS receiver moves, the error correction is applied to each satellite's pseudorange. The satellites used for position determination are chosen based on the "quality" of the satellite. Here, "quality" can mean the geometry of the satellite relative to the earth and the absence of SIA. With the combination of GPS and Glonass satellites to choose from, the four or five highest quality satellites are used for the position calculation. The method contemplates the addition of a new satellite to the current "quality" set of satellites being used for position determination. Range from the new satellite is compared to the range of the GPS receiver using the position based on the current "quality" set of satellites. Thus, a range correction for the new satellite is continuously computed. Once the new satellite is added to the "quality" set of satellites being used for position determination, the range correction is continuously applied to the new satellite to enhance accuracy.