Attitude Determination Performance Research Articles

GNSS/IMU integrated navigation heading angle enhancement algorithm based on dual-antenna TDCP

In the integrated navigation system of Global Navigation Satellite System (GNSS) and Inertial Measurement Unit (IMU), attitude estimation, especially accurate estimation of heading angle, is particularly important for real-time monitoring of vehicle driving status. However, since IMU is divergent in the altitude channel, its error will gradually accumulate if it is not accurately constrained. Therefore, the estimation accuracy of heading angle is insufficient in vehicle-mounted applications where the heading angle changes frequently. In order to solve the problem of poor navigation attitude estimation accuracy in the loose combination of traditional GNSS and IMU, this paper proposes a GNSS/IMU integrated navigation heading angle enhancement algorithm based on dual-antenna epoch carrier phase difference (TDCP). This method solves the vehicle heading angle through dual-antenna TDCP to increase the input dimension of the integrated navigation filter fusion observation value, and uses Hatch filtering and anti-error adaptive filtering to improve the observation domain pseudorange accuracy and GNSS/IMU integrated navigation positioning and attitude determination performance respectively. Experimental results show that compared with the traditional GNSS/IMU integrated navigation method, the proposed algorithm improves the positioning and speed measurement accuracy in the three-dimensional direction by and respectively 22.12%, 41.27%and the vehicle heading angle accuracy is improved 46.29%.

Detection of Degraded Star Observation Using Singular Values for Improved Attitude Determination.

This study introduces an innovative approach aimed at enhancing the accuracy of attitude determination through the computation of star observation quality. The proposed algorithm stems from the inherent invariance of singular values under attitude transformations, leveraging the concept of assessing error magnitude through the deviation of singular values. Quantization becomes imperative to employ this error magnitude as a weighting factor within the attitude determination process. To fulfill this purpose, this study applies p-value hypothesis testing to calculate quantized error levels. Simulation results validate that the calculated weights derived from the proposed algorithm lead to a discernible enhancement in attitude determination performance.

An Effective Sensor Architecture for Full-Attitude Determination in the HERMES Nano-Satellites

The High Energy Rapid Modular Ensemble of Satellites (HERMES) is a constellation of 3U nano-satellites for high energy astrophysics. The HERMES nano-satellites' components have been designed, verified, and tested to detect and localize energetic astrophysical transients, such as short gamma-ray bursts (GRBs), which are the electromagnetic counterparts of gravitational wave events, thanks to novel miniaturized detectors sensitive to X-rays and gamma-rays. The space segment is composed of a constellation of CubeSats in low-Earth orbit (LEO), ensuring an accurate transient localization in a field of view of several steradians exploiting the triangulation technique. To achieve this goal, guaranteeing a solid support to future multi-messenger astrophysics, HERMES shall determine its attitude and orbital states with stringent requirements. The scientific measurements bind the attitude knowledge within 1 deg (1σa) and the orbital position knowledge within 10 m (1σo). These performances shall be reached considering the mass, volume, power, and computation constraints of a 3U nano-satellite platform. Thus, an effective sensor architecture for full-attitude determination was developed for the HERMES nano-satellites. The paper describes the hardware typologies and specifications, the configuration on the spacecraft, and the software elements to process the sensors' data to estimate the full-attitude and orbital states in such a complex nano-satellite mission. The aim of this study was to fully characterize the proposed sensor architecture, highlighting the available attitude and orbit determination performance and discussing the calibration and determination functions to be implemented on-board. The presented results derived from model-in-the-loop (MIL) and hardware-in-the-loop (HIL) verification and testing activities and can serve as useful resources and a benchmark for future nano-satellite missions.

High-Rate Attitude Determination of Moving Vehicles With GNSS: GPS, BDS, GLONASS, and Galileo

We investigate the long-term performance and improvement of high-rate multiconstellation Global Navigation Satellite System (GNSS) or multi-GNSS attitude determination in a dynamical environment and evaluate how much each GNSS contributes to such an improvement with applications to land vehicle navigation. We build a multiantenna GNSS system with three nondedicated receivers and conduct two experiments with quad-constellations in GNSS-friendly and GNSS-challenged environments on January 19 and 23, 2018, respectively. A high-grade inertial measurement unit (IMU) provides a reference of comparison for dynamic attitude solutions. In the static case, the global positioning system (GPS), BeiDou navigation satellite system (BDS), and GLObal NAvigation Satellite System (GLONASS) single-constellation solutions have basically the same performance for both experiments. In the dynamic case, GPS achieves the best accuracy in the experiment on January 19, while on January 23, GPS and GLONASS achieve very similar accuracy and significantly outperform BDS in the pitch and roll components. The different dynamic performances of these single constellations are primarily attributed to their differences in observation noise level and satellite geometry strength. By combining GPS, BDS, GLONASS, and Galileo, the multi-GNSS solution performs significantly better than any single-constellation solution. The average improvements in the dynamic cases are 26.2%, 40.7%, and 36.0% on January 19 and 19.2%, 30.0%, and 36.2% on January 23 in the yaw, pitch, and roll components, respectively. The attitude solutions on January 19 are always better determined than on January 23 in the dynamic cases, which should clearly indicate the importance of combining multiple GNSS constellations and the benefit of more observed satellites and a stronger satellite geometry in GNSS-challenged environments. We also introduce the concept of “influence rate” and quantitatively analyze the contribution of each GNSS system to the combined attitude solution.

Spacecraft attitude determination using electrostatically suspended gyroscope with rotating rings

This article presents a novel method for satellite attitude determination, using two electrostatically suspended gyroscopes (ESGs). In this method, two superconducting rings (like gimbals) rotated around each suspended spherical rotor, which causes a variable flux in the rings. A voltage will be induced in the rings according to Faraday’s law of induction. Satellite attitude is determined by integrating of the induced voltages and strap-down rate gyros using the extended Kalman filter. This gyroscope works precisely when the rotor is maintained at the center of the gyroscope cavity, between three pairs of the circular electrodes, and then a backstepping control algorithm is designed for this purpose. The performance of attitude determination using such sensor and designed control algorithm is evaluated by six-degree-of-freedom simulation of a satellite in the MATLAB software. The simulations show the proposed algorithm works in an excellent manner and has lower than a few hundred arc second errors. The accurately aligning of rotors in the known direction to space is essential and is another problem that we do not address here.

Star Identification and Attitude Determination With Projective Cameras

Images of starfields collected by a projective camera are useful for a variety of scientific and engineering purposes. This utility is exemplified by star trackers, which are amongst the most commonly used sensors for determining the attitude of modern spacecraft. While the literature on star identification and star-based attitude determination is extensive, most algorithms are developed in an ad hoc manner. This work provides a comprehensive and systematic framework for invariant-based star identification and shows most past star identification algorithms to be special cases within this framework. The new star identification framework is found to motivate new problems in attitude determination and sensor self-calibration. Specifically, new algorithms are presented for simultaneous attitude determination and camera calibration for a generic wide field-of-view sensor using a single starfield image. In the special case where camera focal length is the only unknown calibration parameter, attitude determination performance of the new algorithm is indiscernible from a perfectly calibrated camera.

Fine-pointing performance and corresponding photometric precision of the Transiting Exoplanet Survey Satellite

The Transiting Exoplanet Survey Satellite (TESS) is an MIT-led, NASA-funded Explorer-class planet finder launched in April 2018. TESS will carry out a 2-year all-sky survey with the primary goal of detecting small transiting exoplanets around bright and nearby stars. The TESS instrument consists of four wide-field cameras in a stacked configuration, providing a combined field of view of 24 deg × 96 deg that spans approximately from the ecliptic plane to the ecliptic pole. In order to achieve the desired photometric precision necessary for the mission, TESS uses the instrument cameras as star trackers during fine-pointing mode to enhance attitude accuracy and stabilization for science operations. We present our approach in quantifying the expected performance of the fine-pointing system and assessing the impact of pointing performance on the overall photometric precision of the mission. First, we describe the operational details of the fine-pointing system with the science instrument being used for star-tracking. Next, we present the testing framework used to quantify the attitude determination performance of the system and the expected attitude knowledge accuracy results, both in coarse-fine pointing hand-off and in nominal fine-pointing conditions. By combining simulations of the instrument and the spacecraft bus, we quantify the closed-loop fine-pointing stability performance of the system in nominal science operations as well as in the case of camera unavailability due to Earth/Moon interference. Finally, we assess the impact of platform pointing stability on the photometric precision of the system using detailed system modeling and discuss the applicability of mitigation techniques to reduce the effect of jitter on TESS science data.

Attitude Determination for Small Satellites with Infrared Earth Horizon Sensors

Infrared Earth horizon sensors are capable of providing attitude knowledge for satellites in low Earth orbit by using thermopile measurements of the Earth’s infrared emission to locate the Earth’s horizon. Because some small satellites, such as CubeSats, have limited resources, a framework was developed that improves the attitude determination performance of an Earth horizon sensing system consisting of inexpensive thermopiles in static dual-mount configurations by leveraging mission geometry properties and improving sensor models. This paper presents an analytical approach to generate an estimate of the nadir vector in the satellite’s body frame from Earth horizon sensor measurements. On-orbit telemetry data from the Microsized Microwave Atmospheric Satellite (MicroMAS) during limb-crossing events were used to assess our model of sensor readings in response to Earth horizon detection. To quantify the expected attitude estimation performance of our method, a detailed simulation of a low-Earth-orbiting satellite was developed with Earth horizon sensors in similar configurations to the MicroMAS sensor system. Our attitude determination method returns an error of 0.16° on average (root-mean-square error of 0.18°) in nadir estimation under a periodic low-frequency attitude disturbance of 4°. A sensitivity analysis was conducted, which takes mounting uncertainty and position error into account, resulting in an additional attitude error of 0.3° for a mounting offset of 0.2° and up to 0.13° error for a 10-km position knowledge error.

Generation of Guide Star Catalog for Star Trackers

In this paper, a novel guide star catalog generation algorithm is presented, which is a crucial part of an advanced star tracker design since the performance and reliability of star identification and attitude determination depend on the guide star selection. First, we propose an analytical method to estimate the stellar instrument magnitude and characterize the associated errors. Those stars whose instrument magnitudes are higher than the star tracker sensitivity constitute the original catalog. Then, the probability model of each star in the original catalog for attitude determination is established as the function of the field of view (FOV), the brightness accuracy, and the mean number of stars in FOV based on the brightness and uniformity principles, and the stars with larger probability are selected as guide stars. The accuracy of photometry method is validated by estimating the Hipparcos catalog instrument magnitude and comparing them with actual data. The efficiency of guide star selection algorithm is demonstrated by generating guide star catalog for a star tracker with a $16 {^{\circ }}\times 16 {^{\circ }}$ FOV.

Odometer, low-cost inertial sensors, and four-GNSS data to enhance PPP and attitude determination

To upgrade the positioning accuracy, re-initialization speed, and attitude determination performance of precise point positioning (PPP) in dynamic applications, we proposed a multi-sensor fusion system consisting of four global navigation satellite systems (GNSSs), namely GPS, BDS, Galileo, and GLONASS, several low-cost inertial sensors, and an odometer. The study shows that the performance of PPP in terms of continuity, reliability, stability, and re-initialization speed improves by such a multi-sensor fusion system. This manifests itself in a significantly increased accuracy. For position solutions, compared to un-aided PPP solutions, the improvements achieved using low-cost inertial navigation system (INS) are about 36.4, 38.7, and 31.3% in the north, east, and vertical components, respectively, and the improvement using odometer are about 1.58, 0.35, and 4.32% relative to the INS-aided PPP solutions. Moreover, using the odometer can provide more than 2.1, 1.4, and 50.6% attitude improvements for roll, pitch, and heading angles compared to the attitude solutions obtained from the INS-aided PPP system. Under GNSS outage conditions, the mean position improvements using the odometer are about 2.3, 1.8, and 8.7%, with maximum increases of 74.6, 74.7, and 28.3%, and the average attitude improvements are about 4.7, 5.4, and 3.3%, with maximum increases of 36.4, 31.7, and 28.9%, respectively. This means that the odometer can enhance the performance of PPP and PPP/INS integration in challenging dynamic conditions.

Performance analysis of Fast Unscented Kalman Filters for Attitude Determination

Attitude determination performance analysis of two newly developed Fast Unscented Kalman Filters for CubeSat platforms is presented. The attitude determination scenario of UNSWs EC0 CubeSat developed by the Australian Centre for Space Engineering Research (ACSER) is used for the simulation experiment. A gyro, a magnetometer, earth and sun sensor observations are simulated and used in various estimation algorithms for state estimation. The state vector consists of the satellites attitude and the gyro bias vector. The EKF, UKF and the new UKFs called the Single Propagation Unscented Kalman Filter (SPUKF) and the Extrapolated Single Propagation Unscented Kalman Filter (ESPUKF) are implemented separately in MATLAB. The computation time and accuracy of all the estimation algorithms are compared. The SPUKF and ESPUKF can reduce the computation time of the UKF by 92.4% and 85.9% respectively in this application, while retaining the estimation accuracy level of the UKF. This makes them more effective than both the EKF and UKF in the resource-constrained case of CubeSats.

BDS and GPS stand-alone and integrated attitude dilution of precision definition and comparison

Attitude Dilution of Precision (ADOP) is an important indicator that reflects the relationship between attitude errors and noise in carrier phase observations for Global Navigation Satellite System (GNSS) attitude determination. Several definitions of the ADOP have been put forward by some scholars so far. However, there is no widely accepted standard ADOP definition currently. Therefore, the most exact ADOP definition need to be selected to compare the attitude determination performance of BDS and GPS stand-alone and integrated system. In this paper, three representative ADOP definitions are studied. Theoretical analysis and data simulation show that the ADOP definition proposed by Gomez is the best among these three definitions. After that, the ADOP for BDS and GPS integrated attitude determination is defined based on the ADOP-Gomez definition. BDS and GPS stand-alone and integrated ADOP are calculated in a three-antenna static attitude determination experiment. The experimental results demonstrate that the ADOP for GPS stand-alone system is on the whole lower than BDS stand-alone system, which means the geometry strength of GPS for attitude determination is stronger than BDS. Even so, the ADOP for BDS is nearly close to GPS in the condition that the visible satellite numbers of BDS and GPS are almost the same. It is also concluded that the ADOP for BDS and GPS integrated system significantly decreases compared with their stand-alone system.

Single-frequency L5 attitude determination from IRNSS/NavIC and GPS: a single- and dual-system analysis

The Indian Regional Navigation Satellite System (IRNSS) has recently (May 2016) reached its full operational capability. In this contribution, we provide the very first L5 attitude determination analyses of the fully operational IRNSS as a standalone system and also in combination with the fully operational GPS Block IIF along with the corresponding ambiguity resolution results. Our analyses are carried out for both a linear array of two antennas and a planar array of three antennas at Curtin University, Perth, Australia. We study the noise characteristics (carrier-to-noise density, measurement precision, time correlation), the integer ambiguity resolution performance (LAMBDA, MC-LAMBDA) and the attitude determination performance (ambiguity float and ambiguity fixed). A prerequisite for precise and fast IRNSS attitude determination is the successful resolution of the double-differenced integer carrier-phase ambiguities. In this contribution, we will compare the performance of the unconstrained and the multivariate-constrained LAMBDA method. It is therefore also shown what improvements are achieved when the known body geometry of the antenna array is rigorously incorporated into the ambiguity objective function. As our ambiguity-fixed outcomes show consistency between empirical and formal results, we also formally assess the precise attitude determination performance for several locations within the IRNSS service area.

A performance improvement method for low-cost land vehicle GPS/MEMS-INS attitude determination.

Global positioning system (GPS) technology is well suited for attitude determination. However, in land vehicle application, low-cost single frequency GPS receivers which have low measurement quality are often used, and external factors such as multipath and low satellite visibility in the densely built-up urban environment further degrade the quality of the GPS measurements. Due to the low-quality receivers used and the challenging urban environment, the success rate of the single epoch ambiguity resolution for dynamic attitude determination is usually quite low. In this paper, a micro-electro-mechanical system (MEMS)—inertial navigation system (INS)-aided ambiguity resolution method is proposed to improve the GPS attitude determination performance, which is particularly suitable for land vehicle attitude determination. First, the INS calculated baseline vector is augmented with the GPS carrier phase and code measurements. This improves the ambiguity dilution of precision (ADOP), resulting in better quality of the unconstrained float solution. Second, the undesirable float solutions caused by large measurement errors are further filtered and replaced using the INS-aided ambiguity function method (AFM). The fixed solutions are then obtained by the constrained least squares ambiguity decorrelation (CLAMBDA) algorithm. Finally, the GPS/MEMS-INS integration is realized by the use of a Kalman filter. Theoretical analysis of the ADOP is given and experimental results demonstrate that our proposed method can significantly improve the quality of the float ambiguity solution, leading to high success rate and better accuracy of attitude determination.

Attitude determination and control for centrifugal tether deployment on the ESTCube-1 nanosatellite

This paper presents the design, development, and pre-launch characterization of the ESTCube-1 Attitude Determination and Control System (ADCS). The design driver for the ADCS has been the mission requirement to spin up the satellite to 360 deg¢s i1 with controlled orientation of the spin axis and to acquire the angular velocity and the attitude during the scientific experiment. ESTCube-1 is a one-unit CubeSat launched on 7 May 2013, 2:06 UTC on board the Vega VV02 rocket. Its primary mission is to measure the Coulomb drag force exerted by a natural plasma stream on a charged tether and, therefore, to perform the basic proof of concept measurement and technology demonstration of electric solar wind sail technology. The attitude determination system uses three-axis magnetometers, three-axis gyroscopic sensors, and two-axis Sun sensors, a Sun sensor on each side of the satellite. While commercial off-the-shelf components are used for magnetometers and gyroscopic sensors, Sun sensors are custom- built based on analogue one-dimensional position sensitive detectors. The attitude of the satellite is estimated on board using an Unscented Kalman Filter. An ARM 32-bit processor is used for ADCS calculations. Three electromagnetic coils are used for attitude control. The system is characterized through tests and simulations. Results include mass and power budgets, estimated uncertainties as well as attitude determination and control performance. The system fulfils all mission requirements.

Attitude control system design and on-orbit performance analysis of nano-satellite—“Tian Tuo 1”

“Tian Tuo 1” (TT-1) nano-satellite is the first single-board nano-satellite that was successfully launched in China. The main objective of TT-1 is technology demonstration and scientific measurements. The satellite carries out the significant exploration of single-board architecture feasibility validation, and it is tailored to the low-cost philosophy by adopting numerous commercial-off-the-shelf (COTS) components. The satellite is featured with three-axis stabilization control capability. A pitch bias momentum wheel and three magnetic coils are adopted as control actuators. The sun sensors, magnetometers and a three-axis gyro are employed as the measurement sensors. The quaternion estimator (QUEST) and unscented Kalman filter (UKF) method are adopted for the nano-satellite attitude determination. On-orbit data received by ground station is conducted to analysis the performance of attitude determination and control system (ADCS). The results show that the design of ADCS for TT-1 is suitable, robust and feasible.

Instantaneous BeiDou–GPS attitude determination: A performance analysis

The advent of modernized and new global navigation satellite systems (GNSS) has enhanced the availability of satellite based positioning, navigation, and timing (PNT) solutions. Specifically, it increases redundancy and yields operational back-up or independence in case of failure or unavailability of one system. Among existing GNSS, the Chinese BeiDou system (BDS) is being developed and will consist of geostationary (GEO) satellites, inclined geosynchronous orbit (IGSO) satellites, and medium-Earth-orbit (MEO) satellites. In this contribution, a BeiDou–GPS robustness analysis is carried out for instantaneous, unaided attitude determination.Precise attitude determination using multiple GNSS antennas mounted on a platform relies on the successful resolution of the integer carrier phase ambiguities. The constrained Least-squares AMBiguity Decorrelation Adjustment (C-LAMBDA) method has been developed for the quadratically constrained GNSS compass model that incorporates the known baseline length. In this contribution the method is used to analyse the attitude determination performance when using the GPS and BeiDou systems. The attitude determination performance is evaluated using GPS/BeiDou data sets from a real data campaign in Australia spanning several days. The study includes the performance analyses of both stand-alone and mixed constellation (GPS/BeiDou) attitude estimation under various satellite deprived environments. We demonstrate and quantify the improved availability and accuracy of attitude determination using the combined constellation.

Instantaneous GPS–Galileo Attitude Determination: Single-Frequency Performance in Satellite-Deprived Environments

New and modernized global navigation satellite systems (GNSSs) are paving the way for an increasing number of applications in positioning, navigation, and timing (PNT). A combined GNSS constellation will significantly increase the number of visible satellites and, thus, will improve the geometry of observed satellites, enabling improvements in navigation solution availability, reliability, and accuracy. In this paper, a global positioning system (GPS) +Galileo robustness analysis is carried out for instantaneous single-frequency GNSS attitude determination. Precise attitude determination using multiple GNSS antennas mounted on a platform relies on successful resolution of the integer carrier-phase ambiguities. The multivariate-constrained least squares ambiguity decorrelation adjustment (MC-LAMBDA) method has been developed to resolve the integer ambiguities of the nonlinearly constrained GNSS attitude model that incorporates the known antenna geometry. In this paper, the method is used to analyze the attitude determination performance of a combined GPS +Galileo system. Special attention is thereby given to the GPS and Galileo intersystem biases (ISBs). The attitude determination performance is evaluated using GPS/Galileo data sets from a hardware-in-the-loop experiment and two real-data campaigns. In the hardware-in-the-loop experiment, a full GPS/Galileo constellation is simulated, and performance analyses are carried out under various satellite-deprived environments, such as urban canyons, open pits, and other satellite outages. In the first real-data experiment, single-frequency GPS data, combined with the data of Galileo in-orbit validation element (GIOVE) satellites GIOVE-A/GIOVE-B (the two experimental Galileo satellites), are used to analyze the two constellation attitude solutions. In the second real-data experiment, we present the results based on single-frequency data from one of the Galileo IOV satellites, combined with the data of GIOVE-A and GPS. We demonstrate and quantify the improved availability, reliability, and accuracy of attitude determination using the combined constellation.

Research on Satellite Multi-Sensor Attitude Determination System

An attitude determination system has been designed for the geocentric pointing triaxial stabilized satellites which employ a continuously running inertial rate sensor in conjunction with sun sensor and earth sensor. Earth/sun sensor data are processed to generate corrections to satellite attitude, gyro constant drift and earth sensor drift bias estimates. An extended Kalman filter based on the attitude determination system is derived in this paper for the satellite using two earth sensors, a two-axis digit sun sensor as attitude sensors and a three-axis gyro for the angular velocity. A simulation model is developed to estimate the attitude determination performance. Simulation results show that precision attitude determination is achieved using the selected attitude hardware and algorithms.

Three-axis attitude determination using incomplete vector observations

Attitude determination refers to determining the orientation of a vehicle relative to its reference coordinate system. This paper presents a new algorithm for three-axis attitude determination using measurement vectors composed of incomplete vector components. The attitude determination performance of the proposed algorithm is compared with those of the TRIAD and QUEST algorithms in a simulation.