Complex Spacecraft Research Articles

Efficient and accurate flexible multibody dynamics modeling for complex spacecraft with integrated control applications

This study presents a novel flexible multibody dynamics modeling method tailored to spacecraft with intricate motion features such as multi-axis antenna actuation, robotic manipulations, and space station module rotation. Using a floating base and a tree-topology structure, the model effectively simulates the kinematics and dynamics of large-angle joint rotations and elastic deformations, leveraging the Lagrangian framework and finite element analysis. An advanced augmented proportional–derivative (APD) control scheme is also introduced, incorporating system dynamics for enhanced predictive control, accommodating complex interactions and nonlinear system behaviors. Our modeling approach, compared with the commercial Adams software, shows similar system responses while reducing computation time by about 70%, highlighting its efficiency and accuracy. Moreover, incorporating the APD strategy into our system enhances tracking precision, achieving a 90% reduction in error compared with conventional proportional–derivative controls, underscoring the benefits of combining dynamic modeling with control improvements.

General Dynamics for Single- and Dual-Axis Rotating Rigid Spacecraft Components

Deriving and propagating a spacecraft’s equations of motion is fundamental to describing its behavior accurately. These equations of motion depend on the spacecraft’s configuration, which includes any physical subsystem such as attitude control devices, solar panels, gimbals, etc. Prior work introduced the backsubstitution method to yield a modular and scalable formulation to develop complex spacecraft dynamics specific to rotating components attached to a rigid hub as effectors. This paper relaxes assumptions made in deriving effector components in prior work, such as mass properties and frame definitions. This produces a general architecture that uses common equations of motion for physically equal parts. The result is an analytical solution of a set of general rotating effector equations of motion that greatly expand the configuration space of spacecraft that can be simulated with the backsubstitution method. In contrast to prior work where the rotations are highly constrained, rigid-body components can rotate about one or two general axes, and the component mass distribution can be general, no longer requiring the component’s principal axis to align with the center of mass or hinge axis. A numerical software solution demonstrates and verifies how these effectors can mimic a range of dynamic spacecraft components.

An Analysis of the Effect of Hall Thruster Plumes on Surface Charging of a Complex Spacecraft Structure

This article aims to conduct an in-depth investigation into the environmental impact of Hall thruster plumes on spacecraft surface charging. The non-uniform plasma plume generated by Hall thrusters may trigger charging and discharging effects, making the assessment of surface charging risks crucial. Through numerical simulations using SPIS system, this study evaluates the surface charging characteristics of a complex spacecraft in orbit, simulating the effects of turning on and off the thrusters, as well as varying distances between the thrusters and the spacecraft. The simulation demonstrates that turning on the thrusters significantly affects spacecraft charging, reducing the potential difference between spacecraft surfaces from 3740 V to 19.2 V, effectively alleviating electrostatic discharge on the spacecraft surface. The closer the thruster is to the spacecraft, the more CEX ions are collected on the surface, influenced by the beam ions, resulting in a surface potential change of 1.3 V, with minor effects on surface potential but contributing to increased deposition contamination on the spacecraft surface.

Cooling process analysis using the energy-flow-diagram method for the complex heat dissipation network with a typical space station cabin

The large thermal inertia, multiple mass storage links, and various heat dissipation modes will seriously affect the cooling process for complex spacecraft. The energy-flow-diagram method can reflect the flow relationship between each link, so this method is first applied in the thermal analysis of spacecraft to explore the proportion of heat transfer allocation between structures in this paper. Taking the “Tianhe” space station as an example, the heat transfer mode and flow direction in the process from heat source to cold source are analyzed, and then the thermal dynamic model of each link is established. According to the above model, the heat transfer and proportion of different heat transfer modes between sections can be obtained, and then the heat flow diagram of the spacecraft can be drawn. Finally, the heat flow distribution under typical instantaneous, full orbital periods and other working conditions is studied. The results show that the instantaneous heat absorption can reach 1.63 kW in the sunlit region and the instantaneous heat release can reach 2.26 kW in the shadow region. According to the transient heat flow in the sunlit region, only 5.18 kW of the 10 kW heat in the cabin is discharged, and nearly half of the energy is stored in the system. When the areal density of the radiator exceeds 11(kg/m2), the heat storage of the radiator will not be obvious. For pulsed heat consumption, when the proportion of high load time is between 0.5 and 0.7, the system shows a good heat transfer effect. In this paper, the analysis of heat flow distribution among spacecraft structures and the energy difference and time difference between heat source and cold source provide an important basis for spacecraft thermal management and optimization.

Simulating Secondary Electron and Ion Emission from the Cassini Spacecraft in Saturn’s Ionosphere

The Cassini spacecraft’s Grand Finale flybys through Saturn’s ionosphere provided unprecedented insight into the composition and dynamics of the gas giant’s upper atmosphere and a novel and complex spacecraft–plasma interaction. In this article, we further study Cassini’s interaction with Saturn’s ionosphere using three-dimensional particle-in-cell simulations. We focus on how electrons and ions, emitted from spacecraft surfaces due to the high-velocity impact of atmospheric water molecules, could have affected the spacecraft potential and low-energy plasma measurements. The simulations show emitted electrons extend upstream along the magnetic field, and for sufficiently high emission rates, charge the spacecraft to positive potentials. The lack of accurate emission rates and characteristics, however, makes differentiation between the prominence of secondary electron emission and ionospheric charged dust populations, which induce similar charging effects, difficult for Cassini. These results provide further context for Cassini’s final measurements and highlight the need for future laboratory studies to support high-velocity flyby missions through planetary and cometary ionospheres.

Optimal hybrid Coulomb control for on-track rendezvous and docking of spacecraft

This paper investigates the dynamics of on-track rendezvous and docking of two spacecraft, and stabilization using hybrid Coulomb control. Modeling electrostatic forces and torques for control of complex spacecraft geometries like cylinders is challenging. Point mass assumption of the spacecraft that disregards the chaser dynamics will lead to errors in force estimation during the terminal docking phase, resulting in a mission failure. This paper uses the effective sphere method to model Coulomb interactions between the chaser and the target. The method is coupled with the chaser’s tumbling motion about its body axes to develop a relationship between electrostatic force and attitude. The relative attitude dynamics of the chaser is then derived and incorporated into the system dynamics. Differential gravity and hybrid thrusters are used to stabilize the relative attitude of the two bodies. The charge-voltage relations are used to compute potential variations for the Coulomb control. An optimal linear quadratic tracking control is proposed for tracking a reference trajectory generated using solutions of Clohessy-Wiltshire-Hill’s equations. Numerical simulations are carried out for both non-linear and linear models of the Coulomb spacecraft to validate the proposed concept. Results have also been compared with an existing voltage feedback controller to demonstrate the merits and challenges of electrostatic actuation for rendezvous and docking.

Adaptive Fuzzy Fault-Tolerant Control of Flexible Spacecraft with Rotating Appendages

This paper focuses on the attitude control problems of spacecraft with external interference and platform actuator failure. The Lagrange method is used to establish dynamic models of complex spacecraft composed of rotating appendages and platform, and the quaternion is used to describe spacecraft attitude kinematics. Second, a fault-tolerant control algorithm that combined adaptive fuzzy control with finite time sliding mode is proposed for the spacecraft platform, and fixed-time control schemes are proposed for rotating parts to achieve stable rotation of the spacecraft components relative to the platform. Finally, a numerical simulation is performed to verify the superiority and effectiveness of the proposed control laws, and comparisons with other control methods are presented.

Research on Impact Location Method of Complex Spacecraft Pressure Vessel Structure

Research on Impact Location Method of Complex Spacecraft Pressure Vessel Structure

Study on Numerical Simulation Methods for Hypervelocity Impact on Large-Scale Complex Spacecraft Structures

This paper aims to study the difference of results in breakup state judgment, debris cloud and fragment characteristic parameter during hypervelocity impact (HVI) on large-scale complex spacecraft structures by various numerical simulation methods. We compared the results of the test of aluminum projectile impact on an aluminum plate with the simulation results of the smooth particle hydrodynamics (SPH), finite element method (FEM)-smoothed particle Galerkin (SPG) fixed coupling method, node separation method, and finite element method-smooth particle hydrodynamics adaptive coupling method under varying mesh/particle sizes. Then based on the test of the complex simulated satellite under hypervelocity impact of space debris, the most applicable algorithm was selected and used to verify the accuracy of the calculation results. It was found that the finite element method-smooth particle hydrodynamics adaptive coupling method has lower mesh sensitivity in displaying the contour of the debris cloud and calculating its characteristic parameters, making it more suitable for the full-scale numerical simulation of hypervelocity impact. Moreover, this algorithm can simulate the macro breakup state of the full-scale model with complex structure and output debris fragments with clear boundaries and accurate shapes. This study provides numerical simulation method options for the follow-up research on breakup conditions, damage effects, debris clouds, and fragment characteristics of large-scale complex spacecraft.

Heuristic Search and Receding-Horizon Planning in Complex Spacecraft Orbit Domains

Spacecraft missions to small celestial bodies face sensitive, strongly non-Keplerian dynamics that motivate the employment of automated sampling-based trajectory planning. However, the scarcity of onboard computing resources necessitates careful formulation of heuristics for efficiently searching the reachable sets, which exhibit complex and finely-detailed structure. We examine a global search heuristic that combines aspects of simulated annealing and hill-climbing to locate sparse regions of the planning domain that simultaneously satisfy numerous geometric and timing constraints associated with remote sensing objectives for points of interest on the central body surface. Subsequently, we demonstrate the use of a receding-horizon implementation of this maneuver-planning strategy to produce mission profiles that fulfill sets of such goals.

Recent Patents for Space Docking Mechanism

Background: Space docking technology and space docking mechanism are indispensable parts of modern complex spacecraft and important means to expand satellite functions in the future. However, there is still some technology to be broken through in the research of their buffer and locking, so that the docking mechanism can be better used in the future. Objectives: Through the introduction and discussion of the characteristics of space docking mechanism patents in recent years, some valuable conclusions are summarized, and the future research and development of space docking mechanism are prospected. Methods: This paper studied the patents of various docking mechanism, and summarized the patents and research progress of docking mechanism in space. Results: With the development of space industry, docking mechanism has become more and more important. So the docking mechanism are needed to achieve the replenishment for long-term spacecraft in orbit, personnel exchange, spacecraft maintenance, and so on. Conclusion: By elaborating on the structural characteristics of the docking mechanism, the importance of the docking mechanism is consulted for investigation. Through the comparison of these patents, it is concluded that weak impact docking mechanism and electromagnetic docking mechanism are the main development trends of docking institutions in the future.

Ground-test validation technologies for Chang’e-5 lunar probe

The complexity and particularity of Chang’e-5 unmanned lunar sample return missions have high demands for ground-test validation of the Chang’e-5 lunar probe. Test requirements cover multisystem levels, including the large-system, system, subsystem, and component levels. Several difficult ground tests are directed against the key processes, such as sampling and packaging, launching on the moon, rendezvous and docking, and sample transferring in lunar orbit, high-speed reentry. Here, we analyze the features of the ground-test validation for the Chang’e-5 lunar probe and the test requirements of each system level and highlight the testing systems, methods, and results of several large-scale comprehensive tests. Finally, we discuss the innovations of ground-test validation technologies for the Chang’e-5 lunar probe. This article provides important references and guidance for ground tests and design validation for future complex spacecraft or deep space probes.

Investigation of the Substitutability of Rubber Compounds with Environmentally Friendly Materials

Rubber is one of the rare materials that can be used in many sectors and for multiple purposes. It can be used in a wide range of frameworks, from very simple coating materials to very complex spacecraft parts. Apart from natural rubber, compounds are also used for different purposes in rubber production. For a product with such a wide range of uses, the sustainability of its compounds is particularly important. The objective of this study is to investigate environmentally friendly and sustainable alternatives for rubber and some compounds, such as fillers and softeners. By doing this research with an academic method, the most suitable option is determined by taking the weights of the factors affecting this decision into consideration. As a result, the most suitable rubber, filler, and softener options are presented.

Robust On-Manifold Optimization for Uncooperative Space Relative Navigation with a Single Camera

Optical cameras are gaining popularity as the suitable sensor for relative navigation in space due to their attractive sizing, power, and cost properties when compared with conventional flight hardware or costly laser-based systems. However, a camera cannot infer depth information on its own, which is often solved by introducing complementary sensors or a second camera. In this paper, an innovative model-based approach is demonstrated to estimate the six-dimensional pose of a target relative to the chaser spacecraft using solely a monocular setup. The observed facet of the target is tackled as a classification problem, where the three-dimensional shape is learned offline using Gaussian mixture modeling. The estimate is refined by minimizing two different robust loss functions based on local feature correspondences. The resulting pseudomeasurements are processed and fused with an extended Kalman filter. The entire optimization framework is designed to operate directly on the manifold, uncoupling the process and measurement models from the global attitude state representation. It is validated on realistic synthetic and laboratory datasets of a rendezvous trajectory with the complex spacecraft Envisat, demonstrating estimation of the relative pose with high accuracy over full tumbling motion. Further evaluation is performed on the open-source SPEED dataset.

Numerical investigation on the standard catastrophic breakup criteria

Hypervelocity collisions are predicted to be the dominant space debris source in the mid-term future, when a critical spatial density of satellites is reached. The NASA Standard Satellite Breakup Model (SSBM) has been adopted by major space agencies for characterizing hypervelocity spacecraft breakups for debris environment modeling. The SSBM is an empirical model based on data from ground tests and observations of on-orbit events. We propose to enhance this database by numerical simulations including a wide range of collision conditions and complex spacecraft models. We established the software tool PHILOS-SOPHIA for systematically studying the effects of on-orbit hypervelocity collisions. A particular focus was laid on the breakup criteria of the SSBM, which defines an energy-to-mass-ratio of 40 J/g being the collision condition for catastrophic fragmentations. We simulated six different scenarios of a complex spacecraft colliding with a small satellite. In the detailed fragmentation analysis, we find both good agreements and clear deviations between the hydrocode results and the SSBM predictions. Particularly, the collision geometry strongly influences the fragmentation damage and the area-to-mass distributions. Depending on the collision vector, impacts on the outer parts of a spacecraft may result in both higher and lower fragmentation in comparison with impacts on the center of mass. The simple breakup criteria does not reflect this complexity and we recommend performing more research. Numerical simulations, thoroughly backed by advanced experiments, can make a significant contribution to improve the accuracy of breakup models.

GRADIENT-BASED OPTIMIZATION OF SPACECRAFT AND AIRCRAFT THERMAL DESIGN

Steady-case thermal analysis plays an important role in dimensioning thermal control systems for spacecrafts and aircrafts. Usually a trial and error approach is used based on engineering judgement and experience. When thermal models become complex or there are conflicting thermal requirements, however, it becomes harder for an engineer to gain insight as to which design decisions will lead to better results. Numerical optimization, on the other hand, could provide a more robust approach for the thermal design of complex spacecraft or aircraft models. In this paper, we suggest a gradient-based multidisciplinary optimization of thermal models where the coupled derivatives of the multidisciplinary system are obtained with the adjoint method. We show that in the case of steady-state thermal analysis, there is an analytic solution of a partial derivatives of implicit heat-transfer equation that can be used to derive total derivatives of the system. We present a practical application of this method by solving a small interplanetary spacecraft thermal optimization problem consisting of one objective, 15 design variables, and 10 constraints. We found that by using gradient-based optimization with exact derivatives, the best results can be achieved by exploring the design space at multiple initial starting points without major computational overhead.

Benchmarking of local feature detectors and descriptors for multispectral relative navigation in space

Optical-based navigation for space is a field growing in popularity due to the appeal of efficient techniques such as Visual Simultaneous Localisation and Mapping (VSLAM), which rely on automatic feature tracking with low-cost hardware. However, low-level image processing algorithms have traditionally been measured and tested for ground-based exploration scenarios. This paper aims to fill the gap in the literature by analysing state-of-the-art local feature detectors and descriptors with a taylor-made synthetic dataset emulating a Non-Cooperative Rendezvous (NCRV) with a complex spacecraft, featuring variations in illumination, rotation, and scale. Furthermore, the performance of the algorithms on the Long Wavelength Infrared (LWIR) is investigated as a possible solution to the challenges inherent to on-orbit imaging in the visible, such as diffuse light scattering and eclipse conditions. The Harris, GFTT, DoG, Fast-Hessian, FAST, CenSurE detectors and the SIFT, SURF, LIOP, ORB, BRISK, FREAK descriptors are benchmarked for images of Envisat. It was found that a combination of Fast-Hessian with BRISK was the most robust, while still capable of running on a low resolution and acquisition rate setup. For large baselines, the rate of false-positives increases, limiting their use in model-based strategies.

A multiple-shooting differential dynamic programming algorithm. Part 2: Applications

A Multiple-Shooting Differential Dynamic Programming Algorithm is applied to a variety of constrained nonlinear optimal control problems, including classic benchmark problems, as well as a robotic arm problem and sensitive spacecraft trajectory optimization problems. The multiple-shooting extension presented in Part 1 is validated, as well as the Powell, Hestenes, and Rockafellar approach used in the treatment of equality and inequality path and terminal constraints. The results for example applications demonstrate the applicability of the algorithm to a variety of trajectory optimization problems. The advantages of the multiple-shooting approach over the single-shooting algorithm is evident in problems with high sensitivity. In particular, convergence of the multiple-shooting algorithm is demonstrated for complex spacecraft trajectory problems that are intractable using the single-shooting formulation.

Enhancement of the attitude dynamics capabilities of the spinning spacecraft using inertial morphing

ABSTRACTIn the previous works by the authors, an efficient method of control of the inversion of the spinning spacecraft was proposed. This method was prompted by the Dzhanibekov’s Effect or Tennis Racket Theorem, which are often seen by many as odd or even mysterious. For the spacecraft, initially undergoing periodic flipping motion, proposed method allows to completely stop these flips by transferring the unstable motion into the regular stable spin. Similarly, the method allows activation of the flipping motion of the spacecraft, which is initially undergoing its stable spin. In this paper, spacecraft designs, which have inertial morphing capabilities, are considered and their advantages are further investigated. For general formulation, the ability of the spacecraft to change its inertial properties, associated with all three principal axes of inertia, are assumed. For simulation of these types of spacecraft systems, extended Euler’s equations are used and peculiar dynamics of the spacecraft is illustrated with a several study cases. Complex spacecraft attitude dynamics manoeuvres, using geometric interpretation, employing angular momentum spheres and kinetic energy ellipsoids, are considered in detail. Contributions of the inertial morphing to the changes of the shape of the kinetic energy ellipsoid are demonstrated and are related to the resultant various feature manoeuvres, including inversion and re-orientation. A method of reduction of the compound rotation of the spacecraft into a single stable predominant rotation around one of the body axes was proposed. This is achieved via multi-stage morphing and employing proposed instalment into separatrices. Implementation of the morphing control capabilities are discussed. For the periodic inversion motions, calculation of the periods of the flipping motion, based on the complete elliptic integral of the first kind, is performed. Flipping periods for various combinations of inertial properties of the spacecraft are presented in a systematic way. This paper discusses strategies to the increase or reduction the flipping and/or wobbling motions. A discovered asymmetric ridge of high periods for peculiar combinations of the inertial properties is discussed in detail. Numerous examples are illustrated with animations in virtual reality, facilitating explanation of the analysis and control methodologies to a wide audience, including specialists, industry and students.

Shock response prediction of the typical structure in spacecraft based on the hybrid modeling techniques

In order to solve the failure of traditional methods in the response prediction for the complex spacecraft under the wide frequency shock load, this paper provides the FE-SEA (Finite Element-Statistical Energy Analysis) hybrid modeling technique to improve the virtual mode synthesis and simulation (VMSS). Taking the L-shape typical structure as an example, the research is developed through the numerical analysis and experiment verification. In the FE-SEA hybrid model of the typical structure, the two honeycomb boards which have a higher modal density are built as the SEA model, while the connection beam that has a larger stiffness is established as FE model. And then the hybrid model is computed with the VMSS code, giving the transient response results. A shock experiment for the typical structure is carried out to verify the correctness of the methodology above. The results indicate that the numerical results have the similar trend and magnitudes with the ones of the experiment in time domain, and the shock response spectrum (SRS) of the numerical results can realize the ±6 dB tolerance limit compared with the experiment results. This paper finds that the FE-SEA hybrid modeling techniques for the typical structure can effectively overcome the problem of the dynamic differences between the substructures under the excitation of shock load, and the combination of FE-SEA and VMSS has the ability to predict the shock responses of the typical structure accurately. The research methods and conclusions achieved in this paper are expected to further extend to the shock response calculation of the complex spacecraft structures.