INS/GNSS Integration with Account for Timing Skew and Displacement of GNSS Antenna. Experience of Practical Realization

We examine two aspects specific to complex data fusion algorithms in integrated strapdown inertial navigation systems aided by global positioning systems, with their inherent spatial separation between the GNSS antenna phase center and the inertial measurement unit, as well as with the timing skew between their measurements. The first aspect refers to modifications of mathematical models used in INS/GNSS integration. The second one relates to our experience in their application in onboard airborne navigation algorithms developed by Moscow Institute of Electromechanics and Automatics.

A Study on the Effect Produced by Instrumental Error of Automated Astronomical System on Landmark Azimuth Accuracy

The paper analyzes how random and systematic components of instrumental error of an automated astronomical system affect the accuracy of the landmark astronomical azimuth. The obtained results can be applied to construct the error mathematical model and to define the mutual orientation of the body axes when designing the system.

Safe Navigation Algorithm for Autonomous Underwater Vehicles

Two safe navigation algorithms for autonomous underwater vehicles are described: algorithm for avoidance of point obstacles including all the moving underwater and surface objects, and limited size bottom objects, and algorithm for bypassing extended obstacles such as bottom elevations, rough lower ice edge, garbage patches. These algorithms are developed for a control system of a heavyweight autonomous underwater vehicle.

Study of a Method for Calculating the Current Accuracy In Map-Aided Navigation Problem

The paper studies a previously proposed method for calculating the current accuracy characteristics of a correlation-extreme search algorithm for solving the map-aided navigation problem. The proposed method is based on the analysis of the ratio of the extreme values of the functional used in the search algorithm for comparing the measured field fragment, and the fragments obtained from a reference map, and on determining the diameter of the set of the given level for this functional. The study is carried out using an example of three spatial geophysical fields: the sea depth field, the field of gravity anomalies, and the anomalous magnetic field; it is focused on their application for underwater vehicle navigation. The specific features of the information and measurement systems used in the survey of these fields, done by means of an underwater robot are described, as well as the procedure simulating the mapping process taking these features into account. The results of computer experiments on comparison of the proposed method for calculating the current accuracy and the method used in the Bayesian algorithm for solving the navigation problem are presented.

Studying the Сonsistency of Extended Kalman Filter in Pedestrian Navigation with Foot-Mounted SINS

The paper focuses on pedestrian navigation with foot-mounted strapdown inertial navigation systems (SINS). Zero velocity updates (ZUPT) during the stance phase are commonly applied in such systems to improve the accuracy. Zero velocity data are processed by the extended Kalman filter (EKF). Zero velocity condition is written in two forms: in reference and body frames. The first form traditional for pedestrian navigation is shown to provide an inconsistent EKF. The second form provides a correct ZUPT algorithm, which is naturally written in so-called dynamic errors. The analyzed algorithm for data fusion from two SINS is based on the bound on foot-to-foot distance. It is shown how EKF inconsistency can be manifested, and how it can be avoided by proceeding back to dynamic errors. The results are obtained analytically using observability theory and covariance analysis.

Numerical Methods of Suboptimal Programs Synthesis for Accelerometer Unit

The paper presents the results of synthesis of calibration programs consisting of 9 and 18 measurement positions. The synthesis was performed by numerical methods for scalar (invariant) technique of accelerometer unit calibration. The resulting programs are compared to the existing calibration programs which have been obtained analytically. The results of mathematical simulation and field experiment confirm the theoretical calculations, as well as the effective application of the obtained calibration programs.

Promising Map-Aided Aircraft Navigation Systems

The paper analyses the development prospects for aircraft navigation systems using onboard geophysical field measurements. Prospective systems that are not widely applied yet are considered: magnetic gradiometers measuring the stationary magnetic field gradient, gravity gradiometers measuring the gravity field gradient, and electromagnetic systems measuring the alternating part of magnetic field. We discuss the main problems to be solved during airborne measurements of these parameters and give an overview of algorithms and hardware solutions. We analyse the results of onboard measurements and estimate the possible navigation accuracy.

Design to Operational Parameters Dependency on Quality Factor of Sensor Mechanical Resonators

The critical functional part of any high performance resonance based sensor is a mechanical resonator. The performance is measured by resonator quality factor (Q-factor). Damping mechanisms such as thermoelastic damping (TED), anchor loss, surface loss, material internal friction, fluid damping and electronics damping are covered in this review with more focus on gyroscope resonators. Dissipations can be reduced by different means. Hence, the effects of various design to operational parameters on the Q-factor for different configurations, sizes and materials are reviewed in detail. Micro scale ring resonators can achieve a Q-factor of the order of hundreds of thousands. Macro scale hemispherical resonators are suitable for ultrahigh Q-factors. High temperature sensor operation is not preferred because of TED, while sub-zero operation is limited by material internal friction. Few orders of dissipation increase are seen with thin film metallic coating due to TED and coating material internal friction. High precision fabrication is mandatory to achieve the designed minimum anchor loss as it is highly sensitive to fabrication imperfections. Q-factor sensitivity to operating pressure is different for different resonator configurations. This review study helps to build a comprehensive mechanical resonator design, realization and operation strategy to achieve high sensor performance. A roadmap on future research requirements for developing compact mass producible CVG type sensors with ultrahigh Q-factor is also highlighted.

Automation of Mobile Gravimeter Quartz Elastic System Manufacturing Technology

The paper describes an improved technology of quartz elastic system manufacturing for the gravimeters of Chekan series; its purpose is to automate the manufacturing processes of the elastic system elements to improve the work quality and performance. The elastic system manufactured using this technology has been tested on a bench and in field, and the results confirmed its compliance with the requirements set for the sensitive elements of modern mobile gravimeters.

Unmanned Ships: Navigation and More

The paper briefly overviews the development of unmanned surface ship technology over the last 20 years. Main problems of their navigation equipment and algorithms, and their compliance with the International Maritime Organization requirements are discussed.