Triaxial Attitude Research Articles

Collaborative attitude stabilization and distributed vibration suppression of satellite with ultra–large flexible antenna

Large flexible radar satellites are widely used in space–based remote sensing for wide–area target observation and high–capacity information transmission. To achieve accurate earth observation and structural stability of an ultra–large flexible satellite in hundred–meter length concurrently, this paper presents two–time–scale collaboration for attitude stabilization and vibration suppression. First, the coupling dynamic model of the satellite with ultra–large flexible antenna is established under space disturbances. Next, singular perturbation with boundary layer correction is employed to decompose attitude and vibration controls in different time scales, respectively. Given the respective decoupling models, the slow subsystem employs an angles–only terminal sliding–mode controller with adaptive switching and input saturation to accomplish high–robustness triaxial attitude stabilization in finite time. For the fast subsystem, distributed piezoelectric actuators with leader–follower consensus and feedback control are applicable to rapid and stable vibration suppression of the ultra–large structure. Finally, simulation results validate the effectiveness and superiority of these control methods on the satellite, where collaborative control effects on multiple key indices including attitude and vibration control accuracy and settling time are significant. This work facilitates high–accuracy and –stability collaborative control of future ultra–large satellites.

Optimized TRIAD-Based Nanosatellite Attitude Determination Using Horizon Sensor and Magnetometer

The aim of this article is to investigate the accuracy of vector measurement-based attitude determination methods for a nanosatellite. Measurements from the horizon sensor and magnetometer are therefore modeled on the body frame. The triaxial Attitude Determination (TRIAD) technique is a widely used and effective method to determine the attitude of a nanosatellite. In this study, the TRIAD method is used with three different approaches to obtain the smallest orientation error of a nanosatellite equipped with magnetometers and horizon sensors. Analysis of covariance is conducted to evaluate the validity and reliability of the attitude determination process. Three modifications of the TRIAD algorithm were tested for accuracy and the most accurate was determined. The analysis provides information on the sources of error and uncertainty associated with the measurement and estimation process. This information is used to improve system performance and the accuracy of attitude outputs.

Reconfiguration control allocation of actuator faults for tailless aircraft with low aspect ratio

The triaxial attitude control of the tailless aircraft depends heavily on the effectiveness of the actuators. Still, the actuators have redundancy characteristics, cross-coupling of rudder effect, and so on. Therefore, the reconfigurable control allocation of the tailless aircraft under typical actuator faults is deeply studied in this paper. The effectiveness and rationality of the incremental control allocation method based on quadratic programming are thoroughly verified for application to maximize the residual control ability of the aircraft, ensure that the aircraft can still complete the flight mission typically, and guarantee flight safety. According to the research principle of surface failures from slight to severe, three typical rudder surface faults are designed successively: Efficiency loss of single actuator, single actuator stuckness, and double actuators combined stuckness. On this basis, the mechanism of reconfiguration allocation after actuator failures is studied, and the residual control ability of the actuator after loss is fully explored. What’s more, the range of allowable reduction of efficiency of each actuator and the acceptable stuck angle range of each actuator are explored, and the most severe failure in the combination of double actuators stuck is obtained. The attitude controller is designed with incremental backstepping (IBKS). The reconstruction allocation adopts a quadratic programming allocation method based on an effective set solver, which can be seamlessly connected with the IBKS method to improve the control accuracy and disturbance immunity effectively.

Application of a PID-like control to the problem of triaxial electrodynamic attitude stabilization of a satellite in the orbital frame

The problem of triaxial attitude stabilization of a satellite in the orbital frame is considered. The problem is raised about the possibility of implementing such a system of electrodynamic attitude control by the type of a PID controller in which the restoring component of the control torque contains a distributed delay. A constructive analytical approach to the nonlinear stability analysis in the problem of triaxial attitude stabilization of a satellite is presented. A theorem on the asymptotic stability of the stabilized angular position of the satellite is proved. The theorem substantiates the possibility of constructing the indicated control system. Nonlinear analysis is based on the Lyapunov direct method and an original construction of Lyapunov–Krasovskii functional. The effectiveness of the designed attitude control with a distributed delay is confirmed by a computer modeling.

Comparison of TRIAD+EKF and TRIAD+UKF Algorithms for Nanosatellite Attitude Estimation

Two most commonly used sensors on nanosatellites are magnetometer and sun sensor. In this paper, magnetometer and sun sensor measurements are combined gyro measurements to produce enhanced attitude estimation. Tri-Axial Attitude Determination (TRIAD) algorithm is used with Kalman filter to form a complete attitude filter. Sun sensor and magnetometer measurements are selected as inputs to TRIAD algorithm and output is fed to Kalman filter as a measurement. Two different Kalman filters, extended and unscented, are used with TRIAD algorithm. A comparison is given between performances of both Kalman filter.

In-Orbit Attitude Determination of the UVSQ-SAT CubeSat Using TRIAD and MEKF Methods.

Ultraviolet and infrared sensors at high quantum efficiency on-board a small satellite (UVSQ-SAT) is a CubeSat dedicated to the observation of the Earth and the Sun. This satellite has been in orbit since January 2021. It measures the Earth’s outgoing shortwave and longwave radiations. The satellite does not have an active pointing system. To improve the accuracy of the Earth’s radiative measurements and to resolve spatio-temporal fluctuations as much as possible, it is necessary to have a good knowledge of the attitude of the UVSQ-SAT CubeSat. The attitude determination of small satellites remains a challenge, and UVSQ-SAT represents a real and unique example to date for testing and validating different methods to improve the in-orbit attitude determination of a CubeSat. This paper presents the flight results of the UVSQ-SAT’s attitude determination. The Tri-Axial Attitude Determination (TRIAD) method was used, which represents one of the simplest solutions to the spacecraft attitude determination problem. Another method based on the Multiplicative Extended Kalman Filter (MEKF) was used to improve the results obtained with the TRIAD method. In sunlight, the CubeSat attitude is determined at an accuracy better than 3 (at one ) for both methods. During eclipses, the accuracy of the TRIAD method is 14, while it reaches 10 (at one ) for the recursive MEKF method. Many future satellites could benefit from these studies in order to validate methods and configurations before launch.

Geometric Calibration and Image Quality Assessment of High Resolution Dual-Camera Satellite

The evaluation of geometric calibration accuracy of high resolution satellite images has been increasingly recognized in recent years. In order to evaluate geometric accuracy for dual-camera satellite images based on the ground control points (GCP), a rigorous geometric imaging model, which was based on the collinear equation of the probe directional angle and the optimized tri-axial attitude determination (TRIAD) algorithm, is presented. Two reliable test fields in Tianjin and Jinan (China) were utilized for geometric accuracy validation of Pakistan Remote Sensing Satellite-1. The experimental results demonstrate a certain deviation of the on-orbit calibration result from the initial design values of the calibration parameters. Therefore, on-orbit geometric calibration is necessary for optical satellite imagery. Within this research, the geometrical performances including positioning accuracy without/with GCP and band registration of the dual-camera satellite were analyzed in detail, and the results of geometric image quality are assessed and discussed. As a result, it is feasible and necessary to establish such a geometric calibration model to evaluate the geometric quality of dual-camera satellite.

Performance Evaluation of Different Grade IMUs for Diagnosis Applications in Land Vehicular Multi-Sensor Architectures

Vehicular positioning systems are necessary for the development of autonomous vehicles and advanced driver assistance systems (ADAS). In recent years, Inertial Measurement Units (IMU) based on micro-electromechanical systems (MEMS) have been included in proposals for multi-sensor positioning system architectures in order to take advantage of their cost and size. The measurement errors propagation to the positioning solution have limited its application for long-term positioning solution. However, it can play a key role in those applications where tri-axial attitude and accelerations can be indicators of curves, slopes, cants, etc. and it can be used as diagnostic of other sensors measurements. This work is focused on the use of IMUs for diagnostic applications and it compares medium-end (xSens MTi-100) and low-end (Bosch BMI160) grade MEMS-based IMUs in an experimental road test using a fusion of a high-end IMU (KVH GEO-FOG), GNSS and wheel speed sensor as reference. In addition, a research question about whether the calibration is the main reason between different grade IMUs has been formulated. Thus, a simple, manufacturable and cost-efficient calibration technique is applied to the low-end IMU in order to compare its performance improvement with the medium-end one. The raw measurements (angular rates and specific forces) and navigation states (tri-axial attitude and accelerations) are considered for diagnosis and they are statistically compared to evaluate the performance of each IMU. It is concluded that the calibration technique used makes the low-end IMU performance similar to that of the medium-end one. Consequently, this work contributes to optimizing the cost of land vehicular positioning systems when choosing the most appropriate sensor based on the accuracy and precision required for the application.

Study of space optical dynamic push-broom imaging along the trace of targets

In order to scan efficiently along the trace of curve-distributed off-track targets, a novel push-broom imaging method is proposed. Firstly, the trace equation is fitted to optimize the number of detectable targets. To achieve the shortest attitude maneuver time, the triaxial attitude of the satellite is solved in real time, and the TDI imaging velocity is made consistent with the direction of the trace. Finally, the ground imaging simulation is performed, and JL-1 Smart Verification Satellite is utilized to verify that the imaging temporal resolution has been improved by more than 4 times.

A Novel Adaptive Kalman Filtering Approach to Human Motion Tracking With Magnetic-Inertial Sensors

This article presents an adaptive Kalman filtering approach to estimate the orientation of human body segments by using magnetic-inertial measurement units (MIMUs) with three-axis gyroscope, accelerometer, and magnetometer. In order to mitigate the negative impact of the external accelerations and ferromagnetic disturbances, the disturbances are modeled by first-order Gauss–Markov processes, and two parallel adaptive Kalman filters containing disturbance models are implemented to eliminate the disturbances. An adaptive factor is introduced to adjust the process noise covariance matrix to compensate for modeling errors induced by unmodeled gyroscope biases and the erroneous process noise covariance matrices. Furthermore, the outliers are checked and discarded by hypothesis tests on the innovation, and the measurement is rejected when the innovation exceeds a given confidence interval. Then, the estimated gravity acceleration and geomagnetic field are used to calculate the orientation quaternion using triaxial attitude determination algorithm. Finally, experiments under different motion scenarios are carried out to evaluate the effectiveness of the proposed method, and the performance of the proposed method is discussed in comparison with existing ones. A forward kinematics three-dimensional (3-D) human motion reconstruction method is proposed to drive the human skeleton model to reproduce human motion with a visual interface based on ROS platform.

LMI-Based Sliding Mode Control of an Underactuated Control Moment Gyroscope System

This paper introduces and evaluates a robust control algorithm based on sliding mode control theory, in which together with the use of the LMI methods the stabilization of an underactuated nonlinear system can be guaranteed. The obtained results are applied to a mechanical system which consists of two single gimbal control moment gyroscopes for triaxial attitude control of a gravity-gradient stabilized tethered satellite system. These objectives are investigated first using analytical methods and then verified by numerical simulations.

Design Concept and Development of a New Spherical Attitude Stabilizer for Small Satellites

This paper presents the description, design concept, and dynamics of a new control moment gyroscope with a spherical rotor, referred to here as a spherical stabilizer. This stabilizer can be used as an alternative low-weight and high-precision triaxial attitude control device for small and experimental satellites. The mechanical design, as well as precision and structural analysis of the mechanism, is studied in detail. A numerical example of a specific satellite is presented and a fatigue simulation using the finite element method is carried out to examine the failure behavior of critical parts of the mechanism. The performance of the proposed mechanism as attitude controller of a small satellite is also studied via numerical simulations.

Attitude Estimation and Control Using Linearlike Complementary Filters: Theory and Experiment

This brief proposes new algorithms for attitude estimation and control, based on fused inertial vector measurements using a linear complementary filters principle. First, $n$ -order direct and passive complementary filters combined with a TRIaxial Attitude Determination algorithm are proposed to give the attitude estimation solutions. These solutions that are efficient with respect to noise include the gyro-bias estimation. Thereafter, the same principle of data fusion is used to address the problem of attitude tracking based on the inertial vector measurements. Thus, instead of using noisy raw measurements in the control law, a new solution of control that includes a linearlike complementary filter to deal with the noise is proposed. The stability analysis of the tracking error dynamics based on the LaSalle’s invariance theorem proved that almost all trajectories converge asymptotically to the desired equilibrium. Simulations and experimental results, obtained with DIY Quad equipped with the APM2.6 autopilot, show the effectiveness and the performance of the proposed solutions.

Improved Kalman-based attitude estimation framework for UAVs via an antenna array

Accurate attitude estimation is crucial for Unmanned Aerial Vehicles (UAVs) in order to facilitate automated activities such as landing or trajectory tracking. Recently antenna array based communication systems have been installed in UAVs. This array structure can also be applied for attitude estimation by computing the line-of-sight (LOS) path between the base station and UAV. In this paper, we propose a complete framework for attitude estimation by exploiting 3D LOS vector obtained from the antenna array system. We present all the steps to incorporate the estimated LOS vector into the TRIaxial Attitude Determination (TRIAD), QUaternion ESTimator (QUEST) and Kalman algorithms. As an additional contribution, the error covariance matrix of the LOS vector is analytically calculated by first finding the phase shift mean squared error using the known perturbation model from Singular Value Decomposition and assuming that the antenna array measured data error can be modeled as a circularly symmetric white noise. We evaluate five array configurations via Monte Carlo simulations. We show that array configurations that provide orthogonal components of the LOS vector achieve a better performance. The usage of more than three pairs of antennas to improve the estimation of the LOS vector is also proposed for low and intermediate signal-to-noise ratio regimes.

Globally convergent adaptive tracking of angular velocity with inertia identification and adaptive linearization

The problem of a rigid body tracking a desired angular velocity trajectory is addressed using adaptive feedback control. An adaptive controller is developed for a planar rotating body tracking a desired angular velocity command. Lyapunov analysis is used to show that tracking is achieved globally. A periodic angular velocity command is then used to identify the inertia parameter. The adaptive controller is implemented on a triaxial attitude control testbed with fan thrusters. A piecewise linear approximation of an observed input non linearity is inverted to obtain improved angular velocity tracking and inertia identification. To eliminate residual tracking error, an adaptive algorithm is used for improved feedback linearization. Lyapunov analysis is used to show boundedness of the angular velocity and inertia estimate errors. The approach is validated by numerical simulation.

Mathematical Models for the Triaxial Attitude Control Testbed

The Triaxial Attitude Control Testbed has been developed as part of a research program at the University of Michigan on multibody rotational dynamics and control. In this paper, equations of motion are derived and presented in various forms. Actuation mechanisms are incorporated into the models; these include fan actuators, reaction wheel actuators and proof mass actuators that are fixed to the triaxial base body. The models also allow incorporation of unactuated auxiliary bodies that are constrained to move relative to the triaxial base body. The models expose the dynamic coupling between the rotational motion of the triaxial base body, the relative or shape motion of the unactuated auxiliary degrees of freedom, and dynamics associated with actuation mechanisms. Many different model simplifications and approximations are developed. Control models for the triaxial attitude control testbed are formulated that reflect specific assumptions.