Satellite Attitude Control System Research Articles

Optimal control of satellite system model using Linear Matrix inequality approach

In this paper, a robust control strategy has been proposed for the satellite attitude control system, namely, ℋ∞ with regional pole constraints. This design method has been applied to eliminate the effects of disturbances and uncertainties, which are inevitable in aerospace applications. A convex optimization approach using Linear Matrix Inequalities (LMIs) has been utilized in this work. The concept of LMI region constraints have been used to guarantee the closed-loop poles lie within a defined region in the complex plane, which helps improve performance in addition to the robustness properties. Therefore, the designed controller can be viewed as a multi-objective controller that guarantees both robustness and performance. Simulation results demonstrate that the developed controller (ℋ∞ with LMI region constraint) performs better than only ℋ∞ and pole placement controllers, in terms of disturbance attenuation, transient response, and control effort.

A Random Forest and Model-Based Hybrid Method of Fault Diagnosis for Satellite Attitude Control Systems

Fault diagnosis is the key technology to guarantee the reliability and safety of satellite attitude control systems. Although model-based methods have achieved good fault diagnosis performance, various factors (such as closed-loop design, model nonlinearity, and external disturbances) in the satellite attitude control systems still bring challenges to fault isolation. Meanwhile, data-driven methods can assist model-based methods for fault diagnosis based on residual signals (generated from model-based methods) and input/output data to relieve the difficulty. Based on the above motivations, a novel model and data dual-driven fault diagnosis approach is proposed in this paper for satellite attitude control systems. Firstly, an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H_i</i> / <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> optimization based fault detection filter is considered as a residual generator, which is designed to be robust against disturbance and sensitive to fault. Then, the occurrence of a fault can be detected based on the residual evaluation. Eventually, a random forest algorithm is developed to achieve fault isolation with system input/output and residual signals. A simulation experiment, including fault detection and fault isolation of single faults and multiple faults, is conducted to show that the proposed approach is effective and better than the other three methods.

Design and Simulation of Satellite Attitude Control Algorithm Based on PID

According to the tasks of mapping and reconnaissance, the satellite needs to adjust its attitude and keep its attitude stable when it is in orbit. Firstly, the kinematic model and dynamic model of satellite attitude are established.Then the digital simulation of satellite attitude control system is built based on the mathematical model of satellite attitude, in which the control modules use PID controller and fuzzy PID controller respectively. Finally, the steady-state performance and dynamic performance of the two controllers are compared and analyzed.The experimental results show that both fuzzy PID control and fuzzy PID control can be used as effective means of attitude control.Both of them have high precision, fast speed and good steady-state performance to achieve the desired attitude. Fuzzy PID control also has the ability of self-tuning controller parameters, which makes the control process smoother.

MICROSCOPE instrument description and validation

This paper focuses on the dedicated accelerometers developed for the MICROSCOPE mission taking into account the specific range of acceleration to be measured on board the satellite. Considering one micro-g and even less as the full range of the instrument with an objective of one femto-g resolution, that leads to a customized concept and a high-performance electronics for the sensing and servo-actuations of the accelerometer test-masses. This range and performance directed the payload development plan. In addition to a very accurate geometrical sensor core, a high performance electronics architecture provides the measurement of the weak electrostatic forces and torques applied to the test-masses. A set of capacitive detectors delivers the position and the attitude of the test-mass with respect to a very steady gold-coated cage made in silica. The voltages applied on the electrodes surrounding each test-mass are finely controlled to generate the adequate electrical field and so the electrostatic pressures on the test-mass. This field maintains the test-mass motionless with respect to the instrument structure. Digital control laws are implemented in order to enable instrument operation flexibility and a weak position detector noise. These electronics provide both the scientific data for MICROSCOPE’s test of the weak equivalence principle and the input for the satellite drag-free and attitude control system.

Redundancy allocation optimizing in the satellite attitude determination and control system based on the exact solution algorithm

The redundancy allocation problem is to find an optimal allocation of redundant components by considering the set of resources and cost constraints. In this research, the satellite attitude determination and control system is studied and its components is introduced, then the reliability of this system is modeled and optimized based on a mathematical approach based on the redundancy allocation. The model studied in this paper is about the structure of a series-parallel system that is in the exact mode of a satellite attitude determination and control system. In this paper, a new approach for modeling and optimization is presented. The mathematical model presented in this paper is into the class of mixed integer non-linear programming (MINLP). Solving these problems is very important for various researchers due to the high mathematical complexity. In this research, a heuristic method is used to the problem exact solution, the results of which have been reported.

Fixed-time attitude cooperative fault-tolerant control with prescribed performance for heterogeneous multiple satellite

This paper mainly investigates the fixed-time cooperative fault-tolerant control problem for heterogeneous satellite attitude control systems with external disturbances, actuator faults, and unknown inertia uncertainties. Firstly, the asymmetric prescribed performance mechanism is utilized to impose desired performance functions on satellite attitude tracking errors. Then, the fixed-time neuroadaptive technique is adopted to approximate unknown system uncertainties, and a novel fixed-time fault-tolerant controller is thus proposed to ensure that the transformed tracking errors converge to a small neighborhood of origin within a fixed time. Moreover, the Lyapunov theory is employed to validate that the closed-loop system is fixed-time stability under the control scheme. Finally, simulations results are carried out to verify the effectiveness of proposed strategy.

Attitude adaptive control of satellites using double-gimbal magnetically suspended control moment gyros

The paper deals with the control of the satellite attitude by means of double-gimbal magnetically suspended control moment gyros (DGMSCMGs). In its first part, the paper presents the dynamics of the DGMSCMGs and the dynamics of the satellite equipped with a DGMSCMG actuator that creates a total satellite applied gyroscopic torque which is generated by the angular rate of the satellite and the angular rates applied to the gyroscopic gimbals. Then, an adaptive satellite attitude control system is designed with actuator and angular rate sensor (both DGMSCMG type), based on the use of the dynamic inversion control technique and a neural network; the latter models an adaptive component of the control law to compensate the negative influence of the dynamic inversion error. The attitude controller mainly consists of a dynamic compensator, a neural network, and a linear observer (for the estimation of the neural network training vector). The novel attitude control architecture is validated in Matlab/Simulink; the analysis of both theoretical concepts and obtained results prove the cancel of the convergence errors, an excellent angular rate precision, as well as robustness to external disturbances.

Robust MPC for tracking changing setpoints in discrete‐time non‐linear systems with non‐additive unknown disturbance

This paper develops a novel observer-based robust tracking predictive controller for discrete-time nonlinear affine systems capable of dealing with changing setpoints and non-additive non-slowly varying unknown disturbance with bounded variations. The existence of disturbance and/or sudden changes in a setpoint may lead to feasibility and stability issues in the stabilizing terminal constraint-based MPC. Since robust tracking MPCs usually consider additive disturbance, the recursive feasibility of these methods may be lost in the presence of non-additive non-slowly varying disturbance. The robust tracking MPC presented here extends the artificial reference-based MPC to deal with both changing setpoints and non-additive non-slowly varying disturbance. The key idea is the addition of tightened input and state constraints as new system constraints. The authors also guarantee the boundedness of disturbance observation error and closed-loop tracking error. In this method, the optimal tracking error converges asymptotically to the terminal region, and the perturbed system tracking error remains in a variable size tube around the optimal tracking error. It is shown that the proposed controller can achieve offset-free tracking in the presence of constant disturbance. The simulation results of the satellite attitude control system are provided to demonstrate the efficiency of the proposed predictive controller.

Attitude control of an underactuated satellite in presence of disturbance torque with optimal motion planning

The failure of mechanical components is a common phenomenon in satellites. This failure can happen in the satellite attitude control system, which causes that the control system of the satellite becomes underactuated. There have been many attempts to control the orientation of underactuated satellites. However, in most studies, the inertia matrix of the satellite is assumed to be diagonal with respect to the body coordinate system, and no limitations on the amount of torque applied by the reaction wheels have been considered. In this paper, at first, it is attempted to control the satellite using the motion planning method. The satellite control inputs are assumed to be cubic spline with some unknown parameters. The spline parameters are determined by minimizing a cost function defined such that the attitude of the satellite tracks desired preset values. Also, in the simulations, the inertia matrix of the satellite is considered non-diagonal and the maximum torques applied by the reaction wheels are considered limited. Then, the effect of disturbance on the controlled satellite is considered which is modeled by some external torques, and the proposed method is modified by repeating the control algorithm in short time horizons. Finally, the method is customized to be used in tracking an object by the satellite in the space which is applicable in time varying maneuvers such as observation and communications. The performance of the proposed method is demonstrated via numerical simulations.

РОБАСТНОЕ УПРАВЛЕНИЕ КОСМИЧЕСКИМ РОБОТОМ-МАНИПУЛЯТОРОМ ПРИ ОБСЛУЖИВАНИИ ГЕОСТАЦИОНАРНОГО СПУТНИКА СВЯЗИ

Methods have been developed for robust control of a space robot-manipulator during the in-flight maintenance of a geostationary communications satellite – replacement of fuel tanks, solar array panels and other replaceable components of the satellite attitude and orbit control system, which leads to significant changes in the inertial parameters of the hard clutch of a space robot with a geostationary satellite. The results of computer simulation for typical dynamic processes at such maintenance of a geostationary communications satellite are presented.

Reliability Modeling and Analysis of Multi-Degradation of Momentum Wheel Based on Copula Function

The momentum wheel is a key component of the satellite attitude control system and has a direct impact on the reliability and overall life of the satellite. The momentum wheel has the characteristics of a high reliability, long life, and complex failure mechanics, which leads to expensive maintenance and a low reliability of the test sample. Therefore, it is challenge to implement an accelerated life test. The traditional life data statistical method has great difficulty in solving the reliability analysis of the momentum wheel. A reliability calculation method based on copula function for multi-degradation is proposed. Firstly, the key factors affecting the reliability of the momentum wheel are analyzed, and the lubricant residual quantity and current are selected as the degradation quantity. Secondly, the wiener process is used to model the degradation of a single degradation quantity, and the edge distribution function of the momentum wheel reliability is obtained. Considering that the correlation between multiple degradation quantities has a non-negligible influence on the reliability analysis result, the copula function is introduced to describe the correlation, and the edge distributions are fused to obtain the joint distribution function of the momentum wheel reliability.

A Three-Stage Data-Driven Approach for Determining Reaction Wheels’ Remaining Useful Life Using Long Short-Term Memory

Reaction wheels are widely used in the attitude control system of small satellites. Unfortunately, reaction wheels failure restricts the efficacy of a satellite, and it is one of the many reasons leading to premature abandonment of the satellites. This study observes the measurable system parameter of a faulty reaction wheel induced with incipient fault to estimate the remaining useful life of the reaction wheels. We achieve this goal in three stages, as none of the observable system parameters are directly related to the health of a reaction wheel. In the first stage, we identify the necessary observable system parameter and predict the future of these parameters using sensor acquired data and a long short-term memory recurrent neural network. In the second stage, we estimate the health index parameter using a multivariate long short-term memory network. In the third stage, we predict the remaining useful life of reaction wheels based on historical data of the health index parameter. Normalized root mean squared error is used to evaluate the performance of the various models in each stage. Additionally, three different timespans (short, moderate, and extended in the scale of small satellite orbit times) are simulated and tested for the performance of the proposed methodology regarding the malfunction of reaction wheels. Furthermore, the robustness of the proposed method to missing values, input frequency, and noise is studied. The results show promising performance for the proposed scheme with accuracy in predicting health index parameter around 0.01–0.02 normalized root mean squared error, the accuracy in prediction of RUL of 1%–2.5%, and robustness to various uncertainty factors, as discussed above.

Simulink-based simulation platform design and faults impact analysis of attitude control systems

AbstractThe satellite attitude control system (SACS) is a complicated system. In order to reflect the relationship among different components in SACS and analyse the impact of component faults on system performance, a complete simulation platform of the SACS based on Simulink is built in this paper. With the embedding of the specific reaction flywheel, gyroscope and earth sensor model, and the design of the controller based on the quaternion feedback, the simulation platform can not only simulate the real SACS at the component level, but it can also realise the injection of component faults for analysing the system performance. Simulations are conducted to verify the performance of the simulation platform. Simulation results show that this simulation platform has the ability to accurately reflect the control performance of the SACS, and the output accuracy of the component model is high. The research results reveal that this simulation platform can provide model support for verifying the algorithm of fault diagnosis, prediction and tolerant control of the SACS. This simulation platform is easy to use and can be expanded and improved.

Orbit and Attitude Control of a GEO Satellite in Station Keeping Flight Mode

In this study, the performance requirements influencing the orbital and attitude control system of a geostationary satellite in the station-keeping flight mode considering the coupling effect of both attitude and orbital motion is determined. Controlling and keeping the satellite in its orbital window have been done using a set of four thrusters located on one side of the satellite body, with considering the coupling effect of the attitude motion on orbital motion. The satellite’s orbital motion could be disturbed by the attitude motion in the allowable orbital window. The main factors conducting this behavior are derived utilizing the satellite attitude and orbital dynamic equations of motion. In the mathematical analysis of this study, the effects of environmental perturbations originating from the oblateness of Earth, third mass gravity like sun and moon, and solar radiation pressure on the satellite dynamic behavior are also considered. Afterward, the condition of using four installed thrusters on one side of the satellite and the reaction wheels in order to control the satellite orbital and attitude motion is investigated. To reduce the satellite attitude’s error, a proportional-derivative controller is employed to activate the reaction wheels properly. The satellite positions in north-south and east-west directions are controlled by a specific array of thrusters in order to maintain in its predefined orbital window. The required amount of velocity variations for a duration of one year via some simulation may demonstrate the effectiveness of the proposed approach in enhancing the orbital maintenance procedure of the satellite.

Transient-Suppressing Initialization for Low-Bandwidth Attitude Controllers

The use of low-bandwidth attitude controllers is a standard solution for spacecraft facing tight frequency-domain requirements for attitude-stable payloads and platforms. However, such controllers have difficulty responding to transients both planned and unexpected. This paper introduces a novel method of controller re-initialization to counteract a transient in progress. This method, the eigenmode initialization, pursues time-optimal performance for a given controller and plant by attempting to suppress the slow eigenmodes of the closed-loop system; the dynamics that remain are a function of the remaining eigenmodes. The derivation of this method from first principles is presented alongside analytical solutions for the ideal response and specific examples for which postinitialization transients decay 5, 7, and 30 times faster than their uninitialized counterparts. The method is extended to account for actuator bias and bound the actual response in the presence of estimation error. Finally, the method is validated through the high-fidelity simulation of a critical mode transition within the attitude control system of a legacy Airbus satellite, demonstrating the eigenmode initialization’s simple and effective implementation despite considerable nonlinearities in the sensor and actuator models employed.

Comparison of the Satellite Attitude Control System Design using the H∞ Method and H∞/MLI with Pole Allocation Considering the Parametric Uncertainty

This paper presents the comparison of the Attitude Control System (ACS) design for a rigid-flexible satellite with two vibrations mode, using the traditional H∞method and the H∞/LMI with pole allocation considering the parametric uncertainty. In the ACS design is important take into account the influence of thestructure’s flexibility, since they can interact with the satellite rigid motion, mainly, during translational and/or rotational manoeuvrer, damaging the ACS. Usually the mathematics model obtained from the linearization and/or reduction of the rigid flexible model loses information about the flexible dynamical behaviour and introduces some uncertainty. The satellite model is represented by a flexible beam connected to a central rigid hub considering a setof parametric uncertainties. Simulations results have shown that the control law designed by the H∞/LMI method has better performance and it is more robust than H∞method since the first was able to support the action of the uncertainty perturbation and to control the rigid flexible satellite attitude and suppressing vibrations.

An active force controlled of small CMG-based satellite

Purpose This paper aims to investigate the attitude control pointing improvement for a small satellite with control moment gyroscopes (CMGs) using the active force control (AFC) method. Design/methodology/approach The AFC method is developed with its governing equations and integrated into the conventional proportional-derivative (PD) controller of a closed-loop satellite attitude control system. Two numerical simulations of an identical attitude control mission namely the PD controller and the PD+AFC controller were carried out using the MATLAB®-SimulinkTM software and their attitude control performances were demonstrated accordingly. Findings Having the PD+AFC controller, the attitude maneuver can be completed within the desired slew rate, which is about 2.14 degree/s and the attitude pointing accuracies for the roll, pitch and yaw angles have improved significantly by more than 85% in comparison with the PD controller alone. Moreover, the implementation of the AFC into the conventional PD controller does not cause significant difference on the physical structure of the four single gimbal CMGs (4-SGCMGs). Practical implications To achieve a precise attitude pointing mission, the AFC method can be applied directly to the existing conventional PD attitude control system of a CMG-based satellite. In this case, the AFC is indeed the backbone for the satellite attitude performance improvement. Originality/value The present study demonstrates that the attitude pointing of a small satellite with CMGs is improved through the implementation of the AFC scheme into the PD controller.

Optimal Factorization of the State-Dependent Riccati Equation Technique in a Satellite Attitude and Orbit Control System

The satellite attitude and orbit control system (AOCS) can be designed with success by linear control theory if the satellite has slow angular motions and small attitude maneuver. However, for large and fast maneuvers, the linearized models are not able to represent all the perturbations due to the effects of the nonlinear terms present in the dynamics and in the actuators (e.g., saturation). Therefore, in such cases, it is expected that nonlinear control techniques yield better performance than the linear control techniques. One candidate technique for the design of AOCS control law under a large maneuver is the State-Dependent Riccati Equation (SDRE). SDRE entails factorization (that is, parameterization) of the nonlinear dynamics into the state vector and the product of a matrix-valued function that depends on the state itself. In doing so, SDRE brings the nonlinear system to a (nonunique) linear structure having state-dependent coefficient (SDC) matrices and then it minimizes a nonlinear performance index having a quadratic-like structure. The nonuniqueness of the SDC matrices creates extra degrees of freedom, which can be used to enhance controller performance, however, it poses challenges since not all SDC matrices fulfill the SDRE requirements. Moreover, regarding the satellite's kinematics, there is a plethora of options, e.g., Euler angles, Gibbs vector, modified Rodrigues parameters (MRPs), quaternions, etc. Once again, some kinematics formulation of the AOCS do not fulfill the SDRE requirements. In this paper, we evaluate the factorization options (SDC matrices) for the AOCS exploring the requirements of the SDRE technique. Considering a Brazilian National Institute for Space Research (INPE) typical mission, in which the AOCS must stabilize a satellite in three-axis, the application of the SDRE technique equipped with the optimal SDC matrices can yield gains in the missions. The initial results show that MRPs for kinematics provides an optimal SDC matrix.

Reconfigurability evaluation for disturbance rejection control systems under actuator outages

This work aims to develop a quantitative reconfigurability evaluation method for control systems with disturbances in the case of actuator outages. The basic idea of this method is to investigate and quantify the performance of the nominal system under the condition that the specified faults are recoverable. We propose a reconfigurability index based on H2 performance that simultaneously considers both the normal scenario and various fault scenarios. A modified Newton–Kleinman algorithm is used to calculate the evaluation index. Guided by the result of the reconfigurability evaluation, the system structure is optimized to achieve a tradeoff between the control performance under normal conditions and the reconfiguration performance under the fault conditions. Finally, the effectiveness of the proposed method is illustrated through two application examples, namely, aircraft and satellite attitude control systems.

Compact and lightweight 3D printed platform for testing attitude determination and control system of small satellites

Ground tests of the attitude control system of small satellites can be performed with a test stand that simulates torque free rotations. It consists of a floating platform mounted on a spherical frictionless air bearing joint and equipped with a balancing system that removes the gravity torque acting upon the system. An important design requirement of such platforms is its reduced weight and inertia. In this work we propose an original lightweight 3D printed floating platform made of polylactide (PLA). The utilization of plastic for structural elements is a novelty for this kind of devices, but it also introduces some challenging aspects. Indeed, the reduced stiffness of PLA, when compared with aluminum commonly used in these applications, negatively affects the balancing process. Nonetheless, thanks to the peculiar design we adopted, the platform shows high performance in terms of structural rigidity and balancing accuracy. Experiments evidence that the platform is able to reduce gravity torques to a few tens of micro Newton meters and a residual offset between the center of mass and center of rotation of about 10 micro meters. These values agree with those of solutions presented in the literature.