Kong Xianren

Combined feedback control and input shaping for vibration suppression of flexible spacecraft

A new control strategy is proposed, which integrates input shaping technique with feedback control for vibration reduction of rigid-flexible spacecraft. This strategy could ensure the achievement of attitude maneuver and the suppression of appendages vibration simultaneously. Considering the absence of the knowledge of modal variables of flexible appendages and the presence of external disturbances, a feedback controller which only requires spacecraft attitude and angular velocity measurement is designed. Combined with the feedback controller, a robust multiple mode input shaper is designed to enhance the system performance. This input shaper requires the eigenvalues of the whole close loop system, rather than the natural frequency and damping ratio of the flexible appendages. Simulation results show that the presented control strategy reduces the system response time and suppresses the vibration of the appendages successfully during the attitude maneuver. In addition, it can provide strong robustness to system parameter uncertainties.

Effect of non-linear in-plane honeycomb core modulus on forced vibration of sandwich beam

Using FE method, the typical honeycomb core modulus is studied, the nonlinear stress-strain relationship with a property of “harden spring” under tensile load and “soften spring” under compress load is obtained. The effect of the height of the core on the analysis of the modulus is discussed, the results are compared with these acquired from Gibson formula. The polynomial fitting method is adopted to get the nonlinear modulus. The Kirchhoff assumption and Galerkin approximation are used to get the equation of motion of the typical honeycomb core sandwich beam. The numerical results are obtained. The nonlinear amplitude-frequency response of forced vibration is discussed.

Dynamics of electro-dynamic tether de-orbiting system for LEO satellites

This paper presents a flexible cable model considering that tether is easy to inflect can be used for analyzing the dynamic behavior of the electro-dynamic tether (EDT) de-orbiting system. The model can describe tether inflecting and bowing under action of electro-dynamic drag and gravity gradient induced force, and the influences on electro motive force and electro-dynamic drag. Two mathematical simulations are employed to show the differences between the flexible cable model and the rigid bar model. Vibration of the EDT system during de-orbiting course is discussed, at which the simulation result shows vertical response is the main vibration way of EDT.

Exploration of magnetic suspension technology used for spacecraft micro-vibration isolation

Spacecraft micro-vibration is still an important issue that influences space remote-sensing resolution and satellite laser communication pointing precision. As its favorable low frequency oscillation suppression performance, active vibration control becomes a main research direction in the micro-vibration abatement. This paper adopts magnetic suspension vibration isolation control method to construct a 6-DOFs Stewart platform with 6 single DOF magnetic suspension actuators, which is used for isolating the micro-vibration generated by 4 single gimbal control moment gyroscopes(SGCMGs) disturbances. Then an integrated model including satellite platform, SGCMGs and magnetic suspension Stewart platform was developed. Finally, a comprehensive simulation proceeded to illustrate the availability of the magnetic suspension vibration isolation strategy.

An improved method of structural random loading identification

Random loading identification has long been a difficult problem for multi-input-multi-output stationary random vibration problems. In this paper, the inverse pseudo-excitation method is used for dealing with such identification problems, and condition number weighted average method is developed to improve the rank defect of the frequency response function matrix during the process of random loading identification; simulation process is given to compare the result between the presented method and routine method. It proves the optimizing result by use of the method; experiments are designed to certify the feasibility of the algorithm, and achieve good results, and the ill-conditioning problem can be conquered to some extent. The condition number of FRF is used to choose the response measuring point, it reduces the workload, and get a accurate result.

GATEUR model updating based on QGA-PSO algorithm

In this paper the quadratic search-based Genetic-Particle Swarm Optimization Algorithm (QGA-PSO) with storage and comparison vector was proposed, which largely improved the efficiency and precision of Genetic-Particle Swarm Optimization Algorithm (GA-PSO). The finite element model (FEM) of the GARTEUR benchmark was updated using QGA-PSO as well as GA-PSO, the updated model can both reproduce the modal properties in the test range and predict the properties out of the test range as well as the modal properties of the structure with modified parameters, which proves the validity of the QGA-PSO model updating method.