GPS/INS

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

Improvements in and relating to precision targeting

Abstract: An aircraft (1) with a SAR images a target area (5) and selects a target in the target area from a known first position (P1) whereat the GPS coordinates of the position are determined and from which the range and monopulse angles of the target are computed to establish the location of the target in three dimensions with associated errors. The aircraft then flies to a second position (P2) whereat the GPS coordinates of the second position are determined and obtains another high resolution image of the target. Again, the range and monopulse angles of the target are computed. Because of the accuracy of the GPS-aided INS, computer aiding to the pilot will make this second designation much easier. Since the position vector between the two known positions can be provided with accuracy to within a few inches due to the accuracy of the GPS receiver with carrier phase tracking, the position of the target is determined largely by the range measurement accuracy of the radar and the two position locations. Since this establishes the location of the target in a GPS coordinate system relative to the position of the aircraft, absolute position errors typically associated with GPS navigation are canceled. The GPS guided weapon, when supplied with the target location in GPS coordinates, is then guided to the target with the high precision available in clear weather conditions. Since the radar and GPS are both fully functional in adverse weather as well as clear weather, there is provided an all-weather solution to precision weapon delivery.

Position detection device and position detection system

Abstract: PROBLEM TO BE SOLVED: To perform the estimation of a present position when positioning by GPS is incapable with high precision. SOLUTION: A security terminal 10 carried by a user receives signals from GPS satellites S1 to S3 on a predetermined cycle to measure a present position and transmits the positioning result to a host apparatus 3 through a telecommunications line 2. The security terminal 10 is provided with height measuring means which is calibrated by the positioning result of the GPS and measures height h from a change in atmospheric pressure, a movement distance measuring section which detects vibrations of the user in the vertical direction and determines a movement distance r with its vibration pulse multiplied by the number of steps, and a direction measuring section such as a gyro. A calculation section performs GPS positioning at positions P-2, P-1, P0. When the GPS positioning becomes inoperable thereafter, since there is a strong possibility that the user has entered a building or the underground, the last measured position P0 is set to be a reference point, and thereafter, a height h, a movement range r, and movement directions θ1, θ2 which are autonomously measured at positions P1, P2, and P3 are added. COPYRIGHT: (C)2006,JPO&NCIPI

Improved precision of strapdown inertial navigation system brought by dual-axis continuous rotation of inertial measurement unit

Abstract: When systemic rotation autocompensation technique is implemented in inertial navigation system (INS), inertial measurement unit (IMU) undergoes intentionally devised mechanical motions. This technique is one of the strategies of improving the system precision performance at the system level. A dual-axis continuous rotation scheme is introduced, and system error equation is derived. The behaviors of different errors are analyzed. It is concluded that the whole error of INS is attenuated effectively. The error model of the dual-axis continuous rotation INS is designed on digital computer, and the theoretical conclusion is validated.

Visual-Inertial Combined Odometry System for Aerial Vehicles

Abstract: The requirement to operate aircraft in GPS-denied environments can be met by using visual odometry. Aiming at a full-scale aircraft equipped with a high-accuracy inertial navigation system INS, the proposed method combines vision and the INS for odometry estimation. With such an INS, the aircraft orientation is accurate with low drift, but it contains high-frequency noise that can affect the vehicle motion estimation, causing position estimation to drift. Our method takes the INS orientation as input and estimates translation. During motion estimation, the method virtually rotates the camera by reparametrizing features with their depth direction perpendicular to the ground. This partially eliminates error accumulation in motion estimation caused by the INS high-frequency noise, resulting in a slow drift. We experiment on two hardware configurations in the acquisition of depth for the visual features: 1 the height of the aircraft above the ground is measured by an altimeter assuming that the imaged ground is a local planar patch, and 2 the depth map of the ground is registered with a two-dimensional laser in a push-broom configuration. The method is tested with data collected from a full-scale helicopter. The accumulative flying distance for the overall tests is approximately 78 km. We observe slightly better accuracy with the push-broom laser than the altimeter.

An Extended Adaptive Kalman Filtering in Tight Coupled GPS/INS Integration

Abstract: In tight coupled GPS/INS integration by using Kalman filtering, the main error includes not only the dynamic model error (INS error), but also the errors caused by the poor geometry of GPS satellites or short of GPS satellites. In this paper, an extended adaptive Kalman filtering algorithm is presented based on the adaptive filter. The new algorithm can not only resist the influence of the dynamic model errors but also control the influence of the errors caused by the poor geometry of GPS satellites by adjusting the coefficient matrix of the predicted states. An actual computation example shows that the new algorithm can degrade the influence of the two kinds of errors and improve the precision of navigation.