A. P. Stepanov

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)).

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.

Calibration of in-run drifts of strapdown inertial navigation system with uniaxial modulation rotation of measurement unit

Errors of a strapdown inertial navigation system (INS) based on navigation grade fiber-optic gyros (FOG) are studied, with the INS measurement unit performing modulation rotation about the axis orthogonal to the vehicle deck. The main focus is made on the problem of reducing the time of gyro in-run drifts calibration, using the GNSS data when the INS is turned on. In addition to velocity and position measurements taken by the GNSS, phase measurements from antennas spaced on a certain baseline are included.

Specific Features of Constructing a Dual-Mode GNSS Gyrocompass as a Tightly-Coupled Integrated System

A task of constructing a tightly-coupled inertial satellite integrated system under the conditions of limited visibility is considered in terms of solving both orientation and navigation problems. To determine the orientation parameters of a moving object, a dual-mode GNSS gyrocompass is implemented, which comprises a gimballess inertial measurement unit (IMU) on fiber-optic gyros (FOG), and two-antenna receiving equipment (RE) of global navigation satellite system (GNSS). Algorithms and errors of a GNSS gyrocompass with antenna baseline at the level of wavelength of carrier frequency and satellite receivers with external reference oscillator are studied. At that, the IMU with the antenna module of GNSS RE operates in reversible modulation rotation mode. A specific feature of this system is that a GNSS gyrocompass can be constructed while observing at least one navigation satellite of GPS or GLONASS; moreover, it has an autonomous operation mode which implements an AHRS scheme and position dead-reckoning based on the IMU and log data in absence of signals from the navigation satellite. The ambiguity of phase measurements and unreliable measurements are removed by referring to the IMU data when forming differential measurements in the integrated system at the level of the first differences of phases. The results of desktop analysis of bed testing data for a prototype system with a GNSS gyrocompass Orion-M (designed by CSRI Elektropribor) comprising GNSS receiving units 2K-363E-62 (RIRV JSC) and FOG-based inertial unit VG 910 (Fizoptika JSC) are presented in the paper.

On the effectiveness of rotation of the inertial measurement unit of a FOG-based platformless ins for marine applications

The errors of an autonomous platformless inertial navigation system (INS) with fiber-optic gyros (FOG), the inertial measurement unit (IMU) of which is mounted in a two-axis gimbal suspension, are analyzed. The quality criteria and the kinematic scheme of the gimbal are considered. The optimal law of IMU rotation from the standpoint of the selected minimum criterion has been calculated. Simulation was carried out to study the effects of different errors of the IMU sensors on the INS accuracy. The results obtained are confirmed by the development tests of a FOG-based INS designed by Concern CSRI Elektropribor.