Shuang Li

Nanjing University of Aeronautics and Astronautics · College of Astronautics

This paper presents a novel and fast solver for the J2-perturbed Lambert problem. The solver consists of an intelligent initial guess generator combined with a differential correction procedure. The intelligent initial guess generator is a deep neural network that is trained to correct the initial velocity vector coming from the solution of the unp...

This paper develops a sequential convex programming approach for Mars entry trajectory planning by range discretization. To improve the accuracy of numerical integration, the range of entry trajectory is selected as the independent variable rather than time or energy. A dilation factor is employed to normalize the entry dynamics and integration int...

In this paper, modeling and high-precision attitude control of large-scale flexible parallel multibody spacecraft (FPMS) are addressed. First, for describing the complex constraint relationship between each body of the multibody system, the dynamic model of flexible spacecraft in the form of differential-algebraic equations (DAEs) is established by...

Tisserand-leveraging transfers (TILTs) were proposed as techniques to achieve an endgame tour with small orbit insertion maneuvers and short flight times in low-energy regions of the planar, circular, restricted three-body problem. This paper presents a new formulation of TILTs with a framework similar to the classical Lambert problem. The develope...

The multi-burn transfer framework based on the moon-to-moon analytical transfer method allows rapid patching of low-energy trajectories in the vicinity of different moons in a planetary system. However, the semimajor axis and eccentricity of intermediate arcs of one transfer mission are fixed in the existent multi-burn strategies. Additional propel...

Callisto is a promising target for future Jovian system exploration due to its high scientific value and low radiation environment. This paper proposes a new low-energy endgame that can achieve a low Δv transfer with short flight times for Callisto orbiting and landing missions. In contrast to the endgames designed for other Galilean moons, the pro...

An inter-satellite link is a key technology that improves control accuracy, transmission efficiency, and autonomous capability of constellations. A satellite’s pointing and tracking abilities mainly determine the inter-satellite link’s performance, which should be validated through an in-orbit test. However, during the construction of the constella...

The environment around asteroids is of significant uncertainties, which could cause great challenges of exploration missions to asteroids. This paper presents a novel approach to stochastic optimal problem in path-constrained trajectory optimization near asteroids based on convex approach. The path constraints that prevent the spacecraft from colli...

This paper presents a reinforcement-learning (RL)-based robust low-thrust guidance method for asteroid approaching under process uncertainties. Markov decision processes with stochastic dynamics are formulated for RL. To overcome the problem of low terminal accuracy in RL-based transfer trajectory design, robust zero-effort-miss/zero-effort-velocit...

Lunar DRO pinpoint return is the final stage of manned deep space exploration via a lunar DRO station. A re-entry capsule suffers from complicated dynamic and thermal effects during an entire flight. The optimization of the lunar DRO return trajectory exhibits strong non-linearity. To obtain a global optimal return trajectory, an entire-flight luna...

For intercepting active defense target, an impact angle constraint guidance law is proposed based on partial differential games. First, the relative motion models of three-player games between interceptor, target, and defense missile are established. The problem of intercepting active defense target is separated into two partial games. Then, two pa...

The Entry Terminal Point Control (ETPC) algorithm generates the guidance command based on the reference trajectory, while it may lead to control saturation because large control corrections are needed to offset the large state error caused by uncertainties. To address this issue, a reduced-order desensitized optimal control method is proposed to re...

The Tianwen-1 probe, used in China’s first Mars exploration mission, features multiple flight phases, numerous spatial pointing constraints, and complex working modes. During the braking and capture process, it faces challenges such as uplink or downlink command delay, unique capture window, post-control “occultation”, short-time significant change...

Periodic orbits are widely used in space missions and are fundamental for us to understand the complex dynamic system of circular restricted three-body problem. However, there are still many potential families of periodic orbits that have not been located and computed. This study aims to generate some new and less-known families of periodic orbits...

This paper investigates the satellite constellation scheduling problem for non-cooperative space object tracking. Different from the traditional earth observation tasks, space object tracking tasks require observation of fast moving targets that may have unpredictable trajectories, and estimation of the position of the targets through cooperative o...

In this chapter, the propagation of high-dimensional uncertainty in Mars atmospheric entry dynamics is investigated. Based on spectral decomposition and random space decomposition, generalized polynomial chaos is modified to efficiently address the uncertainty quantification task. Comparison simulations demonstrate its effectiveness in quantifying...

This chapter mainly discusses the dynamics of Mars entry and theories related to convex optimization, uncertainty quantification, and robust optimization.

This chapter describes the Mars entry trajectory optimization in presence of uncertainties and control saturation by use of desensitized optimal control (DOC) methodology and Direct Collocation and Nonlinear Programming (DCNLP). The final height and the state sensitivities are simultaneously included into the weighted performance index. Monte Carlo...

This chapter addresses the Mars atmospheric entry guidance by use of command generator tracker based direct model reference adaptive controller to eliminate the effect of the bounded uncertainties on atmospheric density and aerodynamic coefficients. The proposed strategy is easily implemented on low-cost, low-weight entry vehicle from a practical p...

This chapter employed reinforcement learning and hp-adaptive pseudospectral method to investigate the interplay between entry guidance and powered descent guidance. The study demonstrates how did they integrated working can bring dramatic reduction in propellant consumption of several tons in powered descent phase for a mid-lift high-mass Mars land...

This chapter proposes indirect sequential convex programming (ISCP) to maximize the Mars entry terminal altitude.

This chapter develops two approaches to the Mars entry trajectory optimization problem. The pseudospectral model predictive convex programming (PMPCP) method allows for the establishment of a pseudospectral sensitivity relation, which reduces the computational load. And the mapped Chebyshev-Gauss-Lobatto pseudospectral model predictive convex progr...

In this chapter, the pseudospectral discretization and modified objective function with penalty terms are used to develop a new P-QCQP entry tracking guidance algorithm to fundamentally reduce the scale of the problem, improve the computational efficiency, and smoothen the control profile based on the original U-QCQP algorithm. Compared with the ex...

Aiming to improve the desired high efficiency under the initial state uncertainty, this chapter is to develop a hybrid trajectory optimization strategy for Mars entry by using PSO and Gauss Pseudospectral Method (GPM).

This paper develops an end-to-end circular-feature-based pose estimation using the time-of-flight (TOF) camera for capturing serviced satellite. First, the docking ring is chosen as the recognized object for pose measurement. Second, a new ellipse detection method is proposed to detect the docking ring. Third, the circular feature is used to estima...

This paper presents an improved alpha shape-based linear interpolation method, and an improved binning method within the continuum method framework for accurate and efficient planar phase space long-term density propagation. The density evolution equation is formulated for the continuum density propagation under the influence of the solar radiation...

面向未来近月空间站部署需求，提出了一种三级修正的长期拟周期近直线晕轨道（NRHO）设计方法。首先，设计了新的离散点选取策略，降低了对参数敏感区域的打靶需求，提高了多点打靶法计算多圈次拟周期NRHO的收敛性能。然后，基于NRHO的对称特性，给出了初始拟周期NRHO圈次延续方法和滚动时域长期拟周期NRHO生成方法，根据拟周期NRHO近月点半径设计了修正策略。使用不同的NRHO进行仿真实验，生成了维持500圈约10年的长期拟周期NRHO。仿真结果表明本方法提高了收敛效率，且能有效生成地月空间长期拟周期NRHO。

This paper studies the bifurcation case for the planar phase space long-term density propagation problem, and presents an improved multi-segment continuum method for accurate and efficient long-term density propagation, by introducing the multi-segment method to the alpha shape triangulation-based linear interpolation method. The density evolution...

The distribution and change of sea surface salinity (SSS) have an important influence on the sea dynamic environment, marine ecological environment, global water cycle, and global climate change. Satellite remote sensing is the only practical way to continuously observe SSS over a wide area and for a long period of time. The salinity retrieval mode...

This book systematically investigates the Mars entry problem from the perspectives of deterministic optimization, uncertainty optimization, and guidance. Began with a detailed review of the robotic missions and human-scaled exploration plans to Mars, theories or concepts of optimal control, uncertainty quantification, robust optimization, model pre...

This paper proposes an ultra-close range real-time pose determination algorithm for space non-cooperative satellite capture missions. The method leverages a Time-of-Flight (ToF) camera to establish a comprehensive pose determination framework, encompassing both pose tracking and pose estimation. Initially, the Iterative Closest Point (ICP) algorith...

The binary polarization state analyzer (PSA) made of magneto-optic crystal (MO) rotators is a promising technology for achieving low-cost and high-efficiency state of polarization (SOP) analysis. To eliminate the influence of wavelength, temperature, and optical power noise on the internal optical components and data analysis of the PSA, a multi-va...

In this paper, a mesh-adaptive Hermite–Simpson sequential convex programming (SCP) method is proposed for solving low-thrust orbit transfer problems efficiently and accurately. First, we develop a Hermite–Simpson convex programming method that utilizes quadratic polynomial control interpolation to improve discretization accuracy. Then, a mesh-adapt...

In this paper, a mesh adaptive Hermite-Simpson sequential convex programming (SCP) method is proposed for solving low-thrust orbit transfer problems efficiently and accurately. First, we develop a Hermite-Simpson convex programming method that utilizes quadratic polynomial control interpolation to improve discretization accuracy. Then, a mesh adapt...

Periodic orbits are widely used in space missions and are fundamental for us to understand the complex dynamic system of circular restricted three body problem. However, there are still many potential families of periodic orbit that have not been located and computed. This study aims to generate some new and less-known families of periodic orbits f...

Due to multiple gravitational perturbations, a probe orbiting around the Jovian moon Europa experiences a complex dynamical behavior. In this paper, long-term evolution behavior analysis of Europa probe under a highly accurate perturbed model is addressed. First, the dynamics under the 2 gravitational perturbations of Europa and Jupiter are investi...

The SSS (sea surface salinity) is an important factor affecting global climate changes, sea dynamic environments, global water cycles, marine ecological environments, and ocean carbon cycles. Satellite remote sensing is a practical way to observe SSS from space, and the key to retrieving SSS satellite products is to establish an accurate sea surfac...

To address the challenge of optimizing the placement of actuators on an asymmetric spacecraft continuum system, this paper develops a rigid–flexible electromechanical coupling dynamic model that integrates the interactions among rigidity, flexibility, and electromechanical coupling effects. The model is constructed using ordinary differential equat...

Integrating the attitude control and power storage subsystems of modern small satellites is of great significance in reducing the total cost of development and deployment in orbit. A combined energy and attitude control system adopts composite flywheels as actuators and energy storage simultaneously. Such small satellites should possess both strong...

The uniform trigonometrization method (UTM) faces two difficulties in solving the Mars entry problem with maximum terminal altitude. One is that two possible solutions need to be evaluated by Pontryagin's minimum principle (PMP). The other one is that using numerical continuation logic to solve the Hamiltonian two-point boundary value problem (TPBV...

To efficiently plan the point-to-point path for a 7-degrees-of-freedom (7-DOF) free-floating space manipulator system, a path planning method based on Legendre pseudospectral convex programming (LPCP) is proposed. First, the non-convex dynamics are approximated by utilizing the first-order Taylor expansion in the vicinity of the initial guess path,...

Jupiter exploration is one of the focuses of deep space exploration in the near future. Design and optimization of trajectories in the Jovian system are crucial technologies for Jupiter exploration missions due to the unique and challenging multi-body dynamical environment. Various methodologies have been proposed and developed. However, there is a...

This article presents a new perspective from control theory to interpret and solve the instability and mode collapse problems of generative adversarial networks (GANs). The dynamics of GANs are parameterized in the function space and control directed methods are applied to investigate GANs. First, the linear control theory is utilized to analyze an...

The accuracy and consistency of Earth observation (EO) instrument radiometric calibration is a fundamental prerequisite for achieving accurate results and delivering reliable predictions. Frequent calibration and validation (Cal/Val) activities are needed during the instrument's lifetime, and this procedure is often extended to historical archives....

To overcome the time-consuming training caused by the sparse reward function in reinforcement learning, an efficient dense reward framework for robust low-thrust trajectory optimization is proposed. The dense reward functions are designed separately for the deterministic and considered uncertain scenarios, including state uncertainties, observation...

To rapidly model the gravity field near elongated asteroids, an intelligent inversion method using Hopfield neural networks (HNNs) is proposed to estimate on-orbit simplified model parameters. First, based on a rotating mass dipole model, the gravitational field of asteroids is characterized using a few parameters. To solve all the parameters of th...

Hypersonic vehicles have complex maneuvering modes and changeable flight trajectories. Therefore, the prior prediction model established for a single flight situation has the problems of low fault tolerance and high modeling cost. To solve this problem, this paper designs a multi-source information fusion filter based on virtual radar constructed b...

In order to solve the problem of large scale of feasible task execution sequences for agile satellite multi-target repetitive observation mission planning,we proposed a hierarchical clustering task planning method with time decoupling of task execution sequence.In this method,the observable windows and task execution windows in the planning process...