DISCRETE VARIABLE STRUCTURE CONTROL OF LINEAR TIME-INVARIANT SYSTEMS WITH TIME DELAY

IntroductionIn recentyears,many methods have been pro-posed for the design of time- delay control sys-tems[1,2 ] and criteria for the stability of time- delaysystems have been developed by many re-searchers[3 ,4] .Time delay in the control systemscan be divided into two classes on the whole.Oneis in measurement of system variables and calcula-tion for required control force,including physicalproperties of equipmentused in the systems or sig-nal transmission.The other is in control for actua-to…     

Dynamic modeling and active control of a strap-on launch vehicle

Dynamic modeling and active control of a strap-on launch vehicle are studied in this paper. In the dynamic modeling, the double-compatible free-interface modal synthesis method is used to establish dynamic model of the system, and its model precision is compared with those of finite element method(FEM), fixedinterface modal synthesis method and free-interface modal synthesis method. In the active control, the swing angle of rocket motor is used as design variable, and the control law design based on the model of mass center motion is adopted to validate the system. Simulation results indicate that the double-compatible model synthesis method can properly approximate the FEM which is used as the benchmark solution, and the model precision of the double-compatible modal synthesis method is obviously higher than those of the fixed-interface and freeinterface modal synthesis methods. Based on the control law design, the deflection of mass center of the launch vehicle is very small.     

Relative Attitude Dynamics and Control of Spacecraft Formation Flying Considering Flexible Panels

As a key technology for orbital applications, researches on spacecraft formation flying (SFF) attract more attention. However, most of existing researches about dynamics and control of SFF focus on rigid spacecrafts without considering the effect of flexible attachments (such as flexible panels). In this paper, relative attitude dynamics and active control of SFF for a flexible spacecraft (follower spacecraft) and a rigid spacecraft (target spacecraft) are investigated. Firstly, a dynamic model of the flexible spacecraft is established by the principle of angular momentum. Then, the equation of relative attitude dynamics between the flexible spacecraft and the rigid spacecraft is derived by the quaternion to represent the attitude relation of the two spacecrafts. Finally, an attitude feedback controller is designed for the SFF system, and its stability is proved by the Lyapunov stability theory. Simulation results indicate that the panel flexibility has an obvious influence on the dynamic behaviour of the system, the designed controller can effectively control the attitude of the two spacecrafts to achieve synchronization, and the elastic vibration of the panels may be suppressed simultaneously.     

Modeling Study of Planar Flexible Manipulator Undergoing Large Deformation

The planar flexible manipulator undergoing large deformation is investigated by using finite element method (FEM). Three kinds of reference frames are employed to describe the deformation of arbitrary point in the flexible manipulator, which are global frame, body-fixed frame and co-rotational frame. The rigid-flexible coupling dynamic equation of the planar flexible manipulator is derived using the Hamilton’s principle. Numerical simulations are carried out in the end of this paper to demonstrate the effectiveness of the proposed model. The simulation results indicate that the proposed model is efficient not only for small deformation but also for large deformation.     

发光二极管在机车电路中的应用

为了减少机车电路故障对铁路运输的干扰，利用发光极管的优良特性，进行机车电路工作状态显示技术研究。提出了解决电路工作状态的显示方案。为排除长期困扰机车运用中的电路故障提供了一条解决途径。     

A STEP-BY-STEP INTEGRAL METHOD FOR ACTIVELY CONTROLLED STRUCTURES

Introduction　　 Since 1 970 s,the researches in active controlofcivil engineering structures have been developedfor30 years[1] .It is now at the stage where full-scale active systems are installed in actual struc-tures and perform well for the purposes intend-ed[2 ,3 ] .Although a significant progress has beenmade,the true potential of active vibration controlremains non- exploited fully[4] .For example,manyof the current operating systems are designed pri-marily on the basis of the classical…