B. A. Blazhnov

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)).

Determinating relative motion trajectory and orientation angles by GNSS phase measurements and micromechanical gyroscope data

A short review of the existing methods for resolving phase measurement ambiguity is given. The general structure of the developed algorithms for solving relative navigation and attitude determination problems by means of GNSS phase measurements is presented. Two GNSS receivers and the azimuthal angular velocity data generated by a strapdown inertial module are used in the attitude determination problem. The original techniques for phase measurement cycles integer search are revealed for both problems. These make it possible to reduce computational costs of ambiguity resolution as compared to existing methods. The results from processing phase single-frequency measurements and micromechanical gyroscope data recorded on board a car and a vessel are presented.

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.

Integrated tightly coupled inertial satellite orientation and navigation system

This paper presents the Russian Research Center, Elektropribor Concern, and the Russian Radionavigation and Time Institute’s integrated inertial-satellite orientation and navigation system with a micromechanical sensor—based strapdown inertial unit and GLONASS and GPS portable receivers. In order to improve the unit’s accuracy in solving the problem of object orientation, the second-order differences of phase measurements on spaced antennas are used. The tests results of the unit are shown and analyzed.

Aircraft navigation using MEMS IMU and ground radio beacons

Navigation of a small-sized aircraft is discussed using integrated data from MEMS-based IMU and receiver of ground radio beacon signals within an integrated tightly-coupled orientation and navigation system (IONS). IONS algorithms and errors in orientation and navigation parameters are considered both during prestart IMU error calibration with external aiding over a limited time interval and during simulation of aircraft flight along a preset path. Data in IONS are integrated using the extended Kalman filter (EKF). In simulation modeling of IONS functioning algorithms in Matlab (Simulink) we used data of bench tests of MEMS sensors developed by Elektropribor.