Vol 7, No 2 (2016)

The term fingerprint-based (FP) positioning includes a wide variety of methods for determining a receiver’s position using a database of radio signal strength measurements that were collected earlier at known locations. Nonparametric methods such as the weighted k-nearest neighbor (WKNN) method are infeasible for large-scale mobile device services because of the large data storage and transmission requirements. In this work we present an overview of parametric FP methods that use model-based representations of the survey data. We look at three different groups of parametric methods: methods that use coverage areas, methods that use path loss models, and methods that use Gaussian mixtures. Within each group we study different approaches and discuss their pros and cons. Furthermore, we test the positioning performance of several of the analyzed approaches in different scenarios using real-world WLAN indoor data and compare the results to those of the WKNN method.

The article presents a method of determining gyro and accelerometer delays during calibration of strapdown inertial navigation systems (SINS) of navigation accuracy. The method uses the Kalman filter in SINS navigation mode and estimates errors in gyro and accelerometer delays and scale factors, sensitivity axes misalignment and drift, coordinates of accelerometer proof masses in the body-fixed frame. Application of SINS navigation mode during calibration reduces the requirements to accuracy of the rate table. The obtained estimates of calibration parameters are self-consistent, minimizing the resulting SINS error. The method was tested during calibration of FOG-based SINS.

A MEMS RR-type gyro design, immune to translational vibration and constant linear accelerations, is proposed. The gyro mechanical performance is improved through arranging the electrodes of the torquer and angular sensor on elastic suspension of certain stiffness. Design features of the proposed gyro are described, analytical formulas relating the natural frequencies of inertial body suspension and the electrode are given, along with the results of mathematical modeling of gyro dynamics on a vibrating foundation.

The equations for the rotor motion of a strapdown electrostatically suspended gyroscope (ESG) in the polar orientation at self-rotation of the ESG housing about the axis aligned in the direction close to the celestial axis are considered. Analytical solutions of motion equations using a deterministic model of the ESG drift are given. The effects of self-rotation on gyro motion parameters and predicted gyro drift errors in the projections on the axes of the equatorial coordinate system are studied. The obtained solutions are shown to be in agreement with the experimental data.

This paper is devoted to navigation of autonomous underwater vehicles (AUV) with a mobile hydroacoustic beacon transported by an autonomous surface vehicle (ASV). Two algorithms for AUV positioning using information on the distance to a single beacon and the data from the onboard autonomous navigation system have been studied. The first algorithm is based on the application of the extended Kalman filter, and the other one uses the particle filter. The simulation of the considered algorithms performance and the results of the sea trials using a marine autonomous robotic complex (MARC), including an AUV and an ASV, are discussed.