Volume 9, Nº 4 (2018)

The data processing problem in attitude and heading reference system based on two units of micromechanical gyroscopes is considered as a special class of information processing problems from two measurement sources. A novel algorithm used for processing the measurements data from two units of micromechanical gyroscopes is proposed, which can improve orientation system performance while reducing the requirements for external sensors. A mathematical error model of micromechanical gyroscopes and orientation system is given, considering the rotation of the measurement units, and the advantages of the proposed method is analyzed in comparison with other algorithms.

The paper presents a multiloop system for noncoherent tracking of the radionavigation parameters of global navigation satellite system (GNSS) signals in autonomous satellite navigation system. Comparative analysis of accuracies of traditional tracking system with discriminators and filter in the tracking loop and the proposed system without discriminators is conducted. RMS errors of estimates, pull-in range and the probability of signal acquisition are studied under various SNR values. Experimental tests of derived noncoherent tracking loop are performed.

Integration of a multiantenna GNSS receiver and inertial sensors (gyroscopes) is proposed to determine attitude parameters using GNSS phase measurements, containing integer ambiguity, and measurements of the absolute rotation rate of a moving vehicle. The potential accuracy of the proposed technology is estimated based on the simulation and full-scale tests. The implementation of the proposed approach is considered.

Since its initial operation in 1982, GLONASS has completed 35 years of service and has passed through eventful journey. Being the first global alternative to GPS, it generated interest among users worldwide. After initiation, the system declined to a period of unstable constellation status; the system has been revitalized and modernized since the end of 2012. This paper presents a concise discussion on initiation, development, decline and revitalization phases of the system and a review on the available research reports which presented the development and advantages of GLONASS as a stand-alone system and as a multi-GNSS component. The paper reviews the experiences of using the advantages of GLONASS from India during its complete service period based on real-time, long-term systematic analysis of data collected over the Indian region both for the initial and the revitalized and modernized phases. Finally, considering the longterm experience of using GLONASS, the paper presents a few issues towards popularization and quality enhancement of GLONASS services from India. This review may be useful in understanding the need, advantages and challenges of using GLONASS from the region.

The new technical solution proposed in this paper significantly reduces costs for creating underwater acoustic networks (UWAN) and their exploitation. Such a network has small energy-efficient nodes (modems that function, for example, as network communication devices, nodes of long-baseline bottom antenna, etc.). The UWAN performance parameters are considered with regard to the network application for positioning and navigation of autonomous underwater vehicles. Of particular interest are the results of the study on latencies of small data packet delivery in a network as well as the probability of delivering small data packets from the source to the final recipient (for example, control commands, sensor data, data on the positions of long-baseline nodes, and sync sequences). The solution is based on the development of a dedicated EviNS Framework (Evologics intelligent Networking Software Framework) installed directly on the platform of the underwater acoustic modem (UWAM) as part of its standard software. The main performance parameters of the digital UWAN, which uses part of the EviNS framework protocols, namely, a combination of the protocol with uncoordinated access to the medium and the routing protocol based on the sequence number controlled flooding, are discussed and the results of the experimental case study are given. The values of probabilities and latencies in data delivery from the source to the recipient obtained in the experiments provide the network user with the information necessary to schedule tasks involving group interaction and real-time coordination of the UWAN nodes, in particular, mobile nodes on underwater vehicles (at least, in the UWAN with a configuration and size similar to those given in the paper).

This paper deals with an expanded two-dimensional (2D) proportional-derivative (PD) command to line-of-sight (CLOS) guidance law which fights the spiral type trajectory of an anti-tank guided missile (ATGM) in the plane perpendicular to the line-of-sight (LOS) or the so called picture plane, in order to improve the transition process performance while putting the missile onto the LOS. The guidance law acts as a classical PD control law within a small predetermined area around the LOS while at missile deviations pointing a position outside this area the control law includes additional nonlinear components connected with the derivatives of the missile position vector in the plane perpendicular to the LOS. The global asymptotic stability of the guidance loop is established by a specific positive definite Lyapunov function. The effectiveness of the proposed approach is illustrated by simulation results. The guidance law enables to decrease the near-field boundary of the missile operational range.

The paper addresses the history of marine gyrocompasses development in the USSR and Russia. It is noted that despite the development and implementation of attitude and heading reference systems (AHRS), strapdown inertial navigation systems, and satellite compasses (SNS-compasses), the classical gyrocompass of both pendulum and adjustable types is and will be still in demand due to its simple operation and low cost along with the accuracy sufficient for safe navigation; therefore, it will require further development and improvement.