Halil Ersin Soken

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Verified

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• PhD
• Professor (Associate) at Middle East Technical University

In this Note, we propose two simple Kalman filter (KF) algorithms for real-time attitude-independent magnetometer bias estimation for spinning spacecraft.First,we show that it is possible to benefit from the spin motion of the spacecraft by building two quasi measurements for the bias estimation. This considerably improves the convergence character...

Magnetometers are an integral part of attitude determination system for the low-Earth orbiting small satellites as they are lightweight, inexpensive and reliable. Yet using magnetometers for attitude determination is not straightforward because of the sensor errors. These errors limit the overall achievable attitude determination accuracy. Thus far...

Small satellites use commercial off-the-shelf sensors and actuators for attitude determination and control (ADC) to reduce the cost. These sensors and actuators are usually not as robust as the available, more expensive, space-proven equipment. As a result, the ADC system of small satellites is more vulnerable to any fault compared to a system for...

This paper proposes two novel covariance-tuning methods to form a robust Kalman filter (RKF) algorithm for attitude (i.e., roll and pitch) estimation using the measurements of only an inertial measurement unit (IMU). KF based and complementary filtering (CF) based approaches are the two common methods for solving the attitude estimation problem. Ef...

A different approach for attitude filtering integrates the filter with one of the static attitude estimators (e.g. QUEST) such that the filter uses the estimated attitude by this estimator as the measurement. Among several advantages such as being robust and providing fast convergence, this architecture is also useful when several measurements are...

This study presents an improved methodology for celestial triangulation optimization in spacecraft navigation, addressing limitations in existing approaches. While current methods like Linear Optimal Sine Triangulation (LOST) provide statistically optimal solutions for position estimation using multiple celestial body observations, their performanc...

This paper presents a methodology for enhancing the safety and reliability of Vertical Takeoff and Landing (VTOL) aircraft operations on vertically moving marine platforms, such as ship decks and offshore oil rigs. Building upon prior work that introduced predictive scheduling algorithms for safe landing on such platforms, this study advances the f...

Magnetometers are essential sensors for Low Earth Orbit satellites, but their accuracy is often affected by sensor errors, requiring real-time calibration. This paper aims to develop, test, and validate a linear Kalman Filter (KF) for real-time calibration of magnetometers in nanosatellites by estimating key parameters such as bias, scale factor, n...

This paper presents a method to estimate relative position vectors between spacecraft equipped with magnetic coils and magnetic field sensors for close proximity operation. Filters can segregate a magnetic field with a particular frequency if spacecraft drive their coils with this specific frequency. The proposed method utilizes the amplitude of th...

This paper presents an algorithm developed for scheduling the landing of an aircraft on a vertically moving marine platform. The algorithm incorporates the relative velocity of the aircraft and marine platform, ensuring a higher probability of landing below the desired relative touchdown velocity. The detection of potential landing instant is depen...

Sea-skimming missiles are missiles which fly very close to sea surface. This is to avoid detection by radar or make it difficult for defense systems to intercept the missile. Sea-skimming missiles are expected to descend to the surface of the water to start avoiding detection as early as possible right after launch. However, this steep descent is a...

Every year, computer processors are becoming more powerful and efficient. This progress allows for using less power for computing or more complex models for embedded systems, especially in aerospace. Nevertheless, computationally limited platforms still exist, and developing more capable and efficient algorithms for such platforms is an open resear...

Lightweight and low-cost magnetic and inertial sensors are commonly used for attitude estimation in a wide range of applications, from motion tracking to autonomous navigation. However, the inherent and external sensor errors and the accelerations due to the actual motion of the platform highly affect the estimation accuracy. This study proposes a...

Autonomy is a crucial issue for space missions today due to the light time delay and uncertain environment. The optical devices currently in the spacecraft system can be utilized for autonomous purposes, such as navigation and detection. Therefore, this study investigates the use of Optical Navigation (OPNAV) for orbit determination in lunar orbit...

This paper presents an algorithm that uses a Mul-tiplicative Extended Kalman Filter to estimate the deterministic errors of a gyroscope in spacecraft applications. These errors include bias, scale factors, and misalignment errors. To develop and test the algorithm, the angular movement of a spacecraft during various maneuvers is modeled. Two sensor...

This study presents a visual-aided inertial navigation technique that can be used for unmanned aircraft in unknown environments. An angular and linear velocity estimation algorithm, which is based on the solution of the Wahba’s problem, is developed using sequential images for visual odometry. It is possible that the visual sensors do not receive c...

This research presents vision-based maneuvering object motion estimation in case of occlusion. Unequal dimension Interactive Multiple Model (UDIMM) approach is applied to increase the motion prediction accuracy when no measurement is available. Current deep learning-based multi-object tracking algorithms cannot track the objects when an occlusion e...

Star trackers (STRs) are widely used for fine attitude estimation. Due to the pro-cessing time for tasks such as star identification, tracking, and attitude solution, a STR can provide the attitude quaternion measurements with a time delay, which may be as high as a few 100 milliseconds. Different methods are availa-ble for incorporating such delay...

Magnetic attitude control is an essential topic in attitude determination and control (ADC) studies as it can be used as the main or backup attitude control method in different scenarios. The magnetic actuation system is advantageous for its low cost, reliability, and ease of implementation when the pointing accuracy requirement is not high. The ma...

In order to make a pinpoint landing on the Moon, the spacecraft's navigation system must be accurate. To achieve the desired accuracy, navigational drift caused by the inertial sensors must be corrected. One way to correct this drift is to use absolute navigation solutions. In this study, a terrain absolute navigation method to estimate the spacecr...

Magnetometers are essential sensors for attitude estimation in small spacecraft due to their robust, inexpensive and lightweight characteristics. However, their direct usage is not applicable due to sensor errors. These errors limit the overall attitude estimation accuracy. This study proposes a complete real-time attitude-independent mag-netometer...

In order to make a pinpoint landing on the Moon, the spacecraft's navigation system must be accurate. To achieve the desired accuracy, navigational drift caused by the inertial sensors must be corrected. One way to correct this drift is to use absolute navigation solutions. In this study, a terrain absolute navigation method to estimate the spacecr...

In this work, BN is presented for FDIR in the attitude determination system of a small satellite. With the help of the BN, the faults/error probabilities in different contributing components that are used for the attitude determination are found, and the source of the fault is isolated. Then according to these probabilities, the recovery is perform...

Bu çalışmada, uzay araçlarında yer alan cayroskop ölçümlerindeki deterministik hataların kestirilmesi maksadıyla, Çarpımsal Genişletilmiş Kalman Filtresi(ÇGKF) temelli bir algoritma geliştirilmiştir. Geliştirilen Kalman filtresinde matematiksel model olarak kinematik denklemler kullanılırken yardımcı sensör ölçümü olarak yıldız izler ölçümleri kull...

Magnetic attitude control is an essential topic in attitude determination and control (ADC) studies as it can be used as the main or backup attitude control method in different scenarios. The magnetic actuation system is advantageous for its low cost, reliability, and ease of implementation when the pointing accuracy requirement is not high. The ma...

The main aim of this study is to design a low-cost attitude filter for nanosatellites. Since Sun sensors and magnetometers are widely used commercial off-the-shelf attitude sensors, the attitude estimation algorithms using these sensors are needed for either primary or backup modes. Throughout the study, QUEST aided multiplicative extended Kalman f...

A star tracker can provide attitude measurement once the detected stars are successfully identified and matched with the catalog information. To increase efficiency and reliability, a technique for identifying stars and estimating attitude in the general lost-in-space case while also tracking the stars in successive measurement frames is presented...

In the absence of gyro sensors, the straightforward approach to estimate the angular velocity is using a dynamics-based attitude filter which can provide angular rate information together with the attitude of the satellite. However, this approach requires also the reference directions for the vector measurements. In this article, assuming that the...

Considering the attitude (i.e., roll and pitch) estimation problem using an inertial measurement unit (IMU) composed of accelerometer and gyroscope triads, this paper proposes a covariancescaling based robust Kalman filter (KF) algorithm. Attitude estimation problem can be solved by KF based and complementary filtering (CF) based methodologies. App...

This paper proposes a novel covariance-scaling based robust adaptive Kalman filter (RAKF) algorithm for attitude (i.e., roll and pitch) estimation using an inertial measurement unit (IMU) composed of accelerometer and gyroscope triads. KF based and complementary filtering (CF) based approaches are the two common methods for solving the attitude est...

A Neural Network (NN) based method to improve the accuracy of a set of analog Sun sensors is presented. Analog Sun Sensors are commonly used on satellites due to their reduced cost, small size and low power consumption. However, especially in Earth imaging satellites, they are prone to the Earth albedo effects. Magnitude and direction of albedo cha...

Nanosatellites have become an integral part of space research in recent years, especially for universities and non-profit organizations. Attitude estimation is a key function that is playing a leading role in the success of their missions. Despite various research and several implemented algorithms, it is difficult to find comprehensive analyses on...

Limitations for small satellite missions encourages researchers and engineers to use on-board equipment for multiple tasks. Thus, both space can be saved and the equipment redundancy can be prevented. For Earth-imaging satellites a prominent equipment that can be used for multiple purposes is the camera. Other than the observation, the taken images...

Manyetometreler ucuz, hafif ve dayanıklı yapılarından dolayı küçük uzay araçlarındaki yönelim belirleme uygulamalarında yaygın şekilde kullanılmaktadır. Fakat doğrudan kullanımları sensör hataları sebebiyle mümkün değildir. Söz konusu hatalar ulaşılabilecek yönelim belirleme hassasiyetini kısıtlamaktadır. Ne var ki ardışık çözüm üreten özyinelemeli...

Kendini birçok görevde kanıtlayan küçük uydular artık bilimsel çalışmalar dâhil daha kapsamlı görevler için de kullanılmaya başlandı. Fakat uydulardaki yer kısıtı sebebiyle, hem görev için faydalı yükleri, hem de görevi yüksek başarım ile gerçekleştirmeyi sağlayacak alt sistemleri birden fazla amaç için kullanmak gerekebiliyor. Bu bağlamda ilgi çek...

Bu çalışma, havadan satıha ve satıhtan satıha kullanılan hassas güdümlü mühimmatlar için geliştirilmesi planlanan, sadece ataletsel sensör ölçümlerinin kullanıldığı yönelim kestirim tekniğini sunmakta ve bu amaçla kullanılabilecek farklı kestirim algoritmalarının karşılaştırmasını yapmaktadır. Farklı Kalman Filtresi (KF) tabanlı yönelim kestirim al...

Bu çalışmada, Türkiye Bölgesel Seyrüsefer Uydu Sistemi (TBSUS) için daha önce yapmış olduğumuz öncül yörünge tasarımları baz alınarak böyle bir sistemin artırım sistemi (İng. augmentation system) olarak tasarlanması için gerekli analizler yapılacaktır. Bu öncül yörünge tasarımlarında konum ve kapsama alanı benzerlikleri nedeniyle Japonya BNUS siste...

Bu bildiride alçak yörüngede gezinen küçük bir yer gözlem uydusunun yönelimini belirlemek ve denetlenmesini sağlamak amacıyla uydu üzerinde gerçek zamanlı koşmaya uygun algoritma tasarlanmış, farklı kiplerdeki performansı incelenmiş ve benzetim karşılaştırmaları ile en uygun tasarımın seçilmesi sağlanmıştır. Uydunun üç eksen yönelim kontrolü hedefl...

Magnetometers are essential sensors for attitude estimation in small spacecraft due to their robust, inexpensive and lightweight characteristics. However, their direct usage is not applicable due to sensor errors. These errors limit the overall attitude estimation accuracy. This study proposes a complete real-time attitude independent magnetometer...

Designing an attitude controller for an Earth-imaging satellite requires precise knowledge of the satellite's attitude dynamics parameters. This study proposes an extended Kalman filter algorithm for estimating the satellite's inertia terms and the reaction wheel alignment angles. Design limitations for the satellite such as the specific attitude a...

JAXA’s ERG (Exploration of Energization and Radiation in Geospace) Spacecraft, which is nicknamed Arase, was launched on 20 December 2016. Arase is a spin-stabilized and Sun-oriented spacecraft. Its mission is to explore how relativistic electrons in the radiation belts are generated during space storms. Two different on-ground attitude determinati...

This paper proposes using TRIAD and Unscented Kalman Filter (UKF) algorithms in a sequential architecture as a part of a small satellite attitude estimation algorithm. This TRIAD+UKF approach can both provide accurate attitude estimates for the satellite and calibrate the magnetometers in real-time. A complete calibration model for the magnetometer...

This paper presents an autonomous multiple model (AMM) estimation algorithm for hybrid systems with sudden changes in their parameters. Estimates of Kalman filters (KFs) that are tuned and employed for different system modes are merged based on a newly defined likelihood function without any necessity for filter interaction. The proposed likelihood...

This study discusses simultaneous adaptation of the process and measurement noise covariance matrixes for a nontraditional attitude filtering algorithm. The nontraditional attitude filtering algorithm integrates the singular value decomposition (SVD) method with the unscented Kalman filter (UKF) to estimate the attitude of a nanosatellite. The SVD...

JAXA's Arase Spacecraft, which is formerly known as Exploration of Energization and Radiation in Geospace (ERG), was launched on 20 December 2016 and has been in orbit for almost 3 years. The spacecraft is spin-stabilized. Its mission is exploring how relativistic electrons in the radiation belts are generated during space storms. Two on-ground att...

All attitude filter designers are familiar with the covariance matrix tuning process for an attitude filter to get an estimate close to the optimal (or sub-optimal) values as much as possible. This is a difficult and time-consuming task. Selected values for the measurement and process noise covariance matrices are decision makers for the filter's p...

We propose an attitude filtering and magnetometer calibration approach for nanosatellites. A complete calibration model for the magnetometers, considering bias, scale factor and nonorthogonality errors, is assumed. Measurements from magnetometers, Sun sensor and gyros are used in the filtering algorithm to estimate satellite's attitude parameters a...

The exploration of energization and radiation in geospace (ERG) satellite, nicknamed “Arase,” is the second satellite in a series of small scientific satellites created by the Institute of Space and Astronautical Science of the Japan Aerospace Exploration Agency. It was launched on December 20, 2016, by the Epsilon launch vehicle. The purpose of th...

Singular Value Decomposition (SVD) and unscented Kalman filter (UKF) are interlaced using the Euler angles as the attitude parameter in order to estimate the satellite's angular motion parameters about center of mass. Magnetometer and sun sensor are used as the vector measurements for SVD in addition to the angular rate measurements from rate gyro...

We propose an attitude filtering and magnetometer calibration approach for nanosatellites. Measurements from magnetometers, Sun sensor and gyros are used in the filtering algorithm to estimate the attitude of the satellite together with the bias terms for the gyros and magnetometers. In the traditional approach for the attitude filtering, the attit...

Singular Value Decomposition (SVD) and unscented Kalman filter (UKF) are interlaced using the Euler angles as the attitude parameter in order to estimate the satellite’s angular motion parameters about center of mass. Magnetometer and sun sensor are used as the vector measurements for SVD in addition to the angular rate measurements from rate gyro...

A three-axis magnetometer (TAM) is as an essential attitude sensor for low-Earth orbiting small satellites. Being light, small and inexpensive make TAM an ideal attitude sensor specifically for nanosatellite missions. Nonetheless, it is a known fact that the accuracy of the TAMs suffers from the electromagnetic interference (EMI) on-board the nanos...

JAXA's ERG (Exploration of Energization and Radiation in Geospace) Spacecraft , which is nicknamed Arase, was launched on 20 December 2016. Arase is a spin-stabilized and Sun-oriented spacecraft. Its mission is exploring how relativ-istic electrons in the radiation belts are generated during space storms. Two different on-ground attitude determinat...

In this study, we propose process noise covariance matrix adaptation (Q-adaptation) for the Singular Value Decomposition (SVD) aided Unscented Kalman Filter (UKF) algorithm. The main aim is to make the algorithm adaptive against the changes in the process noise covariance. The SVD-aided Adaptive UKF (SaAUKF) estimates the attitude and attitude rate...

In this study, we propose process noise covariance matrix adaptation (Q-adaptation) for the Singular Value Decomposition (SVD) aided Unscented Kalman Filter (UKF) algorithm. The main aim is to make the algorithm adaptive against the changes in the process noise covariance. The SVD-aided Adaptive UKF (SaAUKF) estimates the attitude and attitude rate...

Magnetometers are an integral part of attitude determination system for the low-Earth orbiting small satellites as they are lightweight, inexpensive and reliable. Yet using magnetometers for attitude determination is not straightforward because of the sensor errors. These errors limit the overall achievable attitude determination accuracy. Thus far...

Spin-stabilization offers a simple attitude control solution, specifically for micro and nanosatellites, and has a large potential for implementation on numerous missions. This paper proposes an attitude estimation algorithm for spin satellites. The algorithm is loosely based on a filter proposed by Bar-Itzhack and Harman. Using a simple Kalman fil...

This paper presents the pseudo-linear estimation approach to the high-rate spinning small spacecraft attitude estimation problem. The sensor suit utilised in the presented approach uses gyro, magnetometer and sun-sensor measurements. The presented estimation technique has been designed particularly for the problem of attitude determination during t...

In this study, we add on to our previous researches for non-traditional filtering the investigation of measurement and process noise covariance adaptation and propose an Adaptive Unscented Kalman Filter (AUKF) for nanosatellite attitude estimation. Singular Value Decomposition (SVD) method runs using the magnetometer and sun sensor measurements as...

This paper presents a pseudo-linear Kalman filter approach for the attitude estimation of a spinning small spacecraft. The presented approach uses the gyro, magnetometer and sun-sensor measurements. It has been designed especially for the attitude estimation problem during the Aalto-1 Plasma Brake Experiment (PBE). The PBE design requires that the...

JAXA's Arase Spacecraft, which is formerly known as Exploration of Energization and Radiation in Geospace (ERG), was launched on 20 December 2016. The spacecraft is spin-stabilized. Its mission is exploring how relativistic electrons in the radiation belts are generated during space storms. Two on-ground attitude determination algorithms are consid...

Two non-traditional approaches for nanosatellite attitude estimation are investigated. In the non-traditional approach for attitude filtering the magnetometer and Sun sensor measurements are first used in the Singular Value Decomposition (SVD) algorithm to determine the spacecraft's attitude. Then the attitude estimates from the SVD are fed into th...

Three-axis attitude estimation for spinning spacecraft is recently of considerable practical interest. In this scope, sequential filtering algorithms are also being studied recently. In this study, we extend our recent research for a nonlinear filtering algorithm for spinning spacecraft attitude estimation. In the filter the attitude of the spacecr...

The integrated Singular Value Decomposition (SVD) and Unscented Kalman Filter (UKF) method can recursively estimate the attitude and attitude rates of a nanosatellite. At first, Wahba's loss function is minimized using the SVD and the optimal attitude angles are determined on the basis of the magnetometer and Sun sensor measurements. Then, the UKF...

When quaternions are used for representing the attitude of a spinning spacecraft in an attitude estimation filter, several problems appear due to their rapid variations. These problems include numerical integration errors and violation of the linear approximations for the filter. In this study, we propose representing the attitude of a spinning spa...

The spin-axis tilt (SAT), which is also known as dynamic imbalance or coning error, is one of the dominant errors deteriorating the attitude determination accuracy of spinning spacecraft. It is experienced as the misalignment of the major principal axis of the spacecraft from the intended body spin axis. This paper evaluates a straightforward SAT e...

This paper presents an autonomous multiple model (AMM) estimation algorithm for systems with sudden parameter changes. Estimates of a bank of Kalman filters (KFs) are merged based on a newly defined likelihood function. The function is composed of two measures, one for weighting the filters during the steady state mode and the other for weighting w...

This paper presents a study on attitude estimation during the Plasma Brake Experiment (PBE) onboard a small satellite. The PBE demands that the satellite be spun at a very high angular velocity, up to 200 deg/s , to deploy the tether using centrifugal force. The spin controller, based on purely magnetic actuation, and the PBE demands accurate attit...

Single-frame and filtering algorithms are two standalone techniques for attitude estimation. Single-frame methods use the measurements obtained at a single point in time and fuse the information from sensors to optimally determine the attitude of the spacecraft. On the other hand, the filtering methods use the spacecraft dynamics information togeth...

A covariance scaling based robust adaptive Kalman filter (RAKF) algorithm is developed for the case of sensor/actuator faults. The proposed RAKF uses variable scale factors for scaling the process and measurement noise covariances and eliminating the effect of the faults on the estimation procedure. At first, the existing covariance estimation base...

The spin-axis tilt, which is also known as dynamic imbalance or coning error, is one of the most significant bias errors deteriorating the attitude determination accuracy for spinning spacecrafts. Although it is a common practical issue for spin spacecraft missions, estimation algorithms for the dynamic imbalance have not been studied and issued we...