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Nonlinear dynamics of flexible tethered satellite system subject to space environment

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Applied Mathematics and Mechanics(English Edition) 2016年第4期37卷 485-500页

作者： Bensong YU dongping jin Hao WEN State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

The paper studies the nonlinear dynamics of a flexible tethered satellite system subject to space environments, such as the J2 perturbation, the air drag force, the solar pressure, the heating effect, and the orbital eccentricity. The flexible tether is modeled as a series of lumped masses and viscoelastic dampers so that a finite multi- degree-of-freedom nonlinear system is obtained. The stability of equilibrium positions of the nonlinear system is then analyzed via a simplified two-degree-freedom model in an orbital reference frame. In-plane motions of the tethered satellite system are studied numerically, taking the space environments into account. A large number of numerical simulations show that the flexible tethered satellite system displays nonlinear dynamic characteristics, such as bifurcations, quasi-periodic oscillations, and chaotic motions.

关键词： tethered satellite system flexible tether model space environment stability,nonlinear dynamics

A High-Efficient Finite Difference Method for Flexible Manipulator with Boundary Feedback Control

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Space(Science & Technology) 2021年第1期2021卷 143-152页

作者： Fushou Liu dongping jin College of Civil Engineering Nanjing Forestry University210037 NanjingChina State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics210016 NanjingChina

The paper presents a high-efficient finite difference method for solving the PDE model of the single-link flexible manipulator system with boundary feedback ***,an abstract state-space model of the manipulator is derived from the original PDE model and the associated boundary conditions of the manipulator by using the velocity and bending curvature of the flexible link as the state ***,the second-order implicit Crank-Nicolson scheme is adopted to discretize the statespace equation,and the second-order one-sided approximation is used to discretize the boundary conditions with excitations and feedback *** last,the state-space equation combined with the boundary conditions of the flexible manipulator is transformed to a system of linear algebraic equations,from which the response of the flexible manipulator can be easily *** simulations are carried out to simulate the manipulator under various excitations and boundary feedback *** results are compared with ANSYS to demonstrate the accuracy and high efficiency of the presented method.

关键词： control boundary excitation

Costate estimation for dynamic systems of the second order

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Science China(Technological Sciences) 2009年第3期52卷 752-760页

作者： WEN Hao jin dongping HU HaiYan Institute of Vibration Engineering Research MOE Key Lab of Structure Mechanics and Control for AircraftNanjing University of Aeronautics and AstronauticsNanjing 210016China

The dynamics of a mechanical system in the Lagrange space yields a set of differential equations of the second order and involves much less variables and constraints than that described in the state space. This paper presents a so-called Legendre pseudo-spectral (PS) approach for directly estimating the costates of the Bolza problem of optimal control of a set of dynamic equations of the second order. Under a set of closure conditions, it is proved that the Karush-Kuhn-Tucker (KKT) multipliers satisfy the same conditions as those determined by collocating the costate equations of the second order. Hence, the KKT multipliers can be used to estimate the costates of the Bolza problem via a simple linear map- ping. The proposed approach can be used to check the optimality of the direct solution for a trajectory optimization problem involving the dynamic equations of the second order and to remove any conver- sion of the dynamic system from the second order to the first order. The new approach is demonstrated via two classical benchmark problems.

关键词： costate estimation second order pseudo-spectral method

Web Layout Design of Large Cavity Structures Based on Topology Optimization

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Computer Modeling in Engineering & Sciences 2024年第3期138卷 2665-2689页

作者： Xiaoqiao Yang Jialiang Sun dongping jin State Key Laboratory ofMechanics and Control for Aerospace Structures College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing210016China

Large cavity structures are widely employed in aerospace engineering, such as thin-walled cylinders, blades andwings. Enhancing performance of aerial vehicles while reducing manufacturing costs and fuel consumptionhas become a focal point for contemporary researchers. Therefore, this paper aims to investigate the topologyoptimization of large cavity structures as a means to enhance their performance, safety, and efficiency. By usingthe variable density method, lightweight design is achieved without compromising structural strength. Theoptimization model considers both concentrated and distributed loads, and utilizes techniques like sensitivityfiltering and projection to obtain a robust optimized configuration. The mechanical properties are checked bycomparing the stress distribution and displacement of the unoptimized and optimized structures under the sameload. The results confirm that the optimized structures exhibit improved mechanical properties, thus offering keyinsights for engineering lightweight, high-strength large cavity structures.

关键词： Topology optimization lightweight design web layout design cavity structure

Model predictive control of rigid spacecraft with two variable speed control moment gyroscopes

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Applied Mathematics and Mechanics(English Edition) 2017年第11期38卷 1551-1564页

作者： Pengcheng WU Hao WEN Ti CHEN dongping jin State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

In this paper, an attitude maneuver control problem is investigated for a rigid spacecraft using an array of two variable speed control moment gyroscopes （VSCMGs） with gimbal axes skewed to each other. A mathematical model is constructed by taking the spacecraft and the gyroscopes together as an integrated system, with the coupling interaction between them considered. To overcome the singular issues of the VSCMGs due to the conventional torque-based method, the first-order derivative of gimbal rates and the second-order derivative of the rotor spinning velocity, instead of the gyroscope torques, are taken as input variables. Moreover, taking external disturbances into account, a feedback control law is designed for the system based on a method of nonlinear model predictive control （NMPC）. The attitude maneuver can be realized fast and smoothly by using the proposed controller in this paper.

关键词： integrated system variable speed control moment gyroscope (VSCMG),nonlinear model predictive control (NMPC)

Simple Method for Tethered Space Debris Retrieval

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Journal of Beijing Institute of Technology 2017年第1期26卷 5-8页

作者： Bensong Yu dongping jin State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

Space debris retrieval problem utilizing a tethered system in an elliptical orbit is studied in this *** analytical control law specified by a tether length rate for retrieval is derived from a dumbbell model of the *** proposed control method can suppress large swings around the local vertical position of the tethered *** such a control strategy,the debris retrieval behaves in asymptotic stable motion towards the expected *** stability of the non-autonomous system during the retrieval control is analyzed using the Floquet *** result demonstrates that an orbital region exists,on which the retrieval process maintains asymptotically *** proposed analytical control law is validated via numerical simulations.

关键词： space debris retrieval analytical control law stability

Equivalent continuum modeling of beam-like truss structures with flexible joints

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Acta Mechanica Sinica 2019年第5期35卷 1067-1078页

作者： Fushou Liu Libin Wang dongping jin Hao Wen College of Civil Engineering Nanjing Forestry UniversityNanjing 210037China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The paper investigated the equivalent continuum modeling of beam-like repetitive truss structures considering the flexibility of joints,which models the contact between the truss member and joint by spring-damper with six directional stiffnesses and ***,a two-node hybrid joint-beam element was derived for modeling the truss member with flexible end joints,and a condensed model for the repeating element with flexible joints was ***,the energy equivalence method was adopted to equivalently model the truss structure with flexible joints and material damping as a spatial viscoelastic anisotropic beam ***,the equations of motion for the equivalent beam model were derived and solved analytically in the frequency *** the numerical studies,the correctness of the presented method was verified by comparisons of the natural frequencies and frequency responses evaluated by the equivalent beam model with the results of the finite element method model.

关键词： Large space truss structure Flexible joint Equivalent continuum modeling Anisotropic beam model Frequency response

Dynamic Simulation of Space Debris Cloud Capture Using the Tethered Net

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Space(Science & Technology) 2021年第1期2021卷 153-163页

作者： Qingtao Wang dongping jin Xiaoting Rui School of Science Nanjing University of Science and TechnologyNanjing 210094China Institute of Launch Dynamics Nanjing University of Science and TechnologyNanjing 210094China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Space debris,especially the space debris cloud,has threatened severely the safety of future space *** the framework of multibody system dynamics,a computational approach is proposed in this study to investigate the dynamics of net deployment and capture of space debris cloud using this net subject to large overall motions and large *** obtain high simulation fidelity of capturing space debris cloud,the gradient deficient beam element of the absolute nodal coordinate formulation(ANCF)is employed to discretize threads which are woven into the *** normal contact force between the net and the debris cloud and among debris particles is computed by using the penalty *** deployment examples are presented to investigate the influences of shooting velocity of bullets and microgravity as well as the angle between the traveling direction of the net and the microgravity direction on the deployment characteristics of the tethered *** capturing examples are given to clarify the effect of the deployment area of the net at the moment it starts to contact with the debris cloud on the capture rate and to demonstrate the effectiveness of the proposed approach for capturing space debris cloud using the net in microgravity conditions.

关键词： Capture debris Simulation

Analytical libration control law for electrodynamic tether system with current constraint

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Astrodynamics 2024年第2期8卷 237-246页

作者： Shidong Xu Ti Chen Hao Wen dongping jin State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

This study focuses on stabilizing the libration dynamics of an electrodynamic tether system(EDTS)using generalized torques induced by the Lorentz *** contrast to existing numerical optimization methods,a novel analytical feedback control law is developed to stabilize the in-plane and out-of-plane motions of a tether by modulating the electric current *** saturation constraint on the current is accounted for by adding an auxiliary dynamic system to the *** enhance the robustness of the proposed controller,multiple perturbations of the orbital dynamics,modeling uncertainties,and external disturbances are approximated using a neural network in which the weighting matrix and approximation error are estimated simultaneously,such that these perturbations are well compensated for during the control design of the ***,a dynamically scaled generalized inverse is utilized to address the singular matrix in the control *** closed-loop system is proven to be ultimately bounded based on Lyapunov stability ***,numerical simulations are performed to demonstrate the effectiveness of the proposed analytical control law.

关键词： electrodynamic tether system(EDTS) libration dynamics analytical control current constraint