G. I. Emel’yantsev

Test bed calibration of fog-based strapdown inertial measurement unit

The paper outlines the method for calibration of a strapdown inertial measurement unit (SIMU) based on fiber-optic gyros (FOG) in dynamic conditions on a test bed. Calculated components of linear velocity vector and position of SIMU accelerometer unit on the test bed platform are used as a reference. The accuracy of a proposed method is estimated by testing the SIMU based on FOGs by IXSEA (France) on three-axis rate table by Acutronic.

Calibration of a precision SINS IMU and construction of IMU-bound orthogonal frame

The paper focuses on construction of reference orthogonal frame bound with inertial measurement system of a strapdown inertial navigation system. Main points of the algorithm refining the FOG IMU calibration parameters in dynamic test bench conditions using the Kalman filter and relying upon the system navigation solution are detailed. Time lags in FOG gyros and accelerometers’ measurement channels are estimated to the accuracy allowing construction of a 0.001 deg/h class navigation system.

Improving the accuracy of GPS compass for small-sized objects

The paper considers determination of attitude parameters, including true heading, by an integrated orientation and navigation system (IONS) comprising MEMS-based inertial measurement unit (IMU) and multiantenna GNSS receiving equipment. IONS generates orientation solution using phase data from two-antenna GNSS module with antenna base about the wavelength of the satellite signal at carrier frequency. The system algorithms and errors are studied. IMU and GNSS antenna base are subjected to modulating rotation. Effectiveness of using GNSS phase determinations for estimating heading errors with a short rotating antenna base is investigated. The system experimental sample uses IMU based on STIM300 Sensonor MEMS sensors (Norway), navigation and phase measurements by GNSS receivers 1K-181 by Russian Institute of Radionavigation and Time (Russia). The results obtained in bench tests are presented.

Using phase measurements for determining a vehicle’s attitude parameters by a GPS-aided inertial system

The problem of determining a vehicle’s attitude parameters is considered. The solution to this problem is based on the integration of data from a strapdown inertial measurement unit (SIMU) on MEMS sensors and two receivers of the Global Navigation Satellite System (GNSS) with spaced antennas with the aim to form phase measurements. The algorithms and errors of a GPS-aided inertial system—integrated attitude and navigation system (IANS)—in attitude determination of a moving vehicle are studied. Coprocessing of data is carried out with the use of the algorithm of an extended Kalman filter (EKF) with feedback for the whole state vector of the system. A specific feature of the IANS considered here is that the data from the SIMU and GNSS receiver unit (RU) are integrated with primary phase measurements from two receivers with antennas spaced on a certain base. The elimination of the phase measurement ambiguity is made possible due to the SIMU data. The results of office studies of the data obtained during sea tests of an SIMU prototype on MEMS sensors, developed by CSRI Elektropribor, and a GNSS RU with two receivers (Ashtech G12 and Kotlin developed by the Russian Institute of Radionavigation and Time, JSC (RIRT)).

Analyzing the feasibility of heading alignment of downhole gyroinclinometers in high latitudes

The paper discusses the problem of heading alignment of downhole gyroinclinometers in latitudes up to 80° N. It is shown that the required alignment accuracy may be achieved using inertial measurement unit with fiber-optic gyros (FOG IMU) or so called global navigation satellite system (GNSS) compass. Test results for FOG IMU (IXSEA) and GNSS compass designed by Elektropribor are represented.

Attitude determination by INS/GNSS system aided by phase and magnetometer measurements for spinning vehicles

The paper considers attitude determination for a vehicle spinning about longitudinal axis by an integrated orientation and navigation system (IONS) comprising MEMS IMU and GNSS receiver.Attitude determination is aided by magnetometer data or phase measurements from closely spaced GNSS receiving antennas. IONS algorithms and errors in attitude determination are analyzed. The paper analyzes the methods to enhance the accuracy of attitude determination and estimation of scale factor errors of gyros and accelerometers with the sensitivity axes aligned with the longitudinal axis.The system experimental sample uses IMU based on STIM300 Sensonor MEMS sensors (Norway), magnetometers and phase measurements of 1K-181 GNSS receivers by the Russian Institute of Radionavigation and Time. The results obtained in bench tests are presented.

Vertical deflection determination in high latitudes using precision IMU and two-antenna GNSS system

The paper studies the possibility of using a well-known inertial geodetic method for determining a gravity field anomaly parameter, namely, vertical deflection (VD), in high latitudes. The proposed problem solution includes designing a specialized integrated system comprising a precision IMU and two-antenna GNSS system with a long antenna baseline. The paper presents the algorithms used to solve the problem, accuracy estimates obtained using simulation modeling in MATLAB (Simulink) and the results of sea trials of the GPS compass designed by Elektropribor.

Improving information autonomy of marine SINS

The paper considers operation algorithms of a strapdown inertial navigation system comprising several angular rate sensors and one position gyro. Such a SINS can be optimally used onboard search underwater vehicles with a long-term autonomous operation in the areas where the sonar logs fail to provide coordinate dead-reckoning due to hydrological conditions. Position gyro data are used in SINS algorithms to obtain the navigation solution. Calibration mode in the vehicle surface position uses GNSS data, and navigation mode in the vehicle submerged position uses water speed log data. Results from MATLAB (Simulink) simulation modeling confirm the effectiveness of applying position gyro data in SINS to significantly improve its information autonomy.

Integrated attitude reference and navigation system for orbital spacecraft

The paper considers an integrated attitude reference and navigation system for an orbital spacecraft. The system comprises a strapdown inertial attitude reference system based on electrostatic gyros (ESGs) and fiber-optic gyros (FOGs). Algorithms for joint processing of ESG and FOG data which use a Kalman filter and the corresponding criteria are described. Results of computer simulation of the system algorithms with MATLAB using ESG and FOG real test data are given.

Calibrating the error of a strapdown ESG-based attitude reference system under conditions of orbital flight

We consider questions of how to ensure the required accuracy with regard to the orientation of remote Earth sensing spacecrafts by means of a strapdown ESG-based attitude reference system. The techniques, models, and algorithms that we employ are described, as are some results from actual flight tests. The ways of further improving the accuracy of inertial system under consideration are discussed.