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 th...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.展开更多
The kinematic accuracy of space manipulator determines whether the spacecraft performs normally or not. Problems pertaining to structural deformation have received increased attention in recent times. In the space man...The kinematic accuracy of space manipulator determines whether the spacecraft performs normally or not. Problems pertaining to structural deformation have received increased attention in recent times. In the space manipulator systems, flexible arms and joints can induce drastic dynamic instabilities. In applications such as the space station, kinematic error due to structural deformation can jointly affect the performance characteristics. And it is crucial for accuracy control of space manipulator to establish a precision index. Here we analyze the dynamics characteristic of flexible space manipulator considering the hysteresis of harmonic reducer based on method of nonconstraint boundary modal. For the sake of describing the output accuracy, we integrate the method of analytic hierarchy process(AHP) to establish a comprehensive evaluation index. A numerical simulation is performed to analyze the nonlinear dynamic characteristics of space manipulator with harmonic reducer. With the analysis of accuracy assessment, the relation among the hysteresis angle, rigidity and output accuracy is revealed. Considering the elastic modulus of flexible space manipulator and the hysteresis angle of harmonic reducer, we conduct an evaluation of output characteristics of flexible space manipulator with the proposed comprehensive evaluation index. The accuracy evaluation of output characteristics based on the proposed comprehensive evaluation index is implemented in the initial stage of space manipulator's design, which can not only solve the problems existing in the design but also save cost savings for ground tests. The results can be used in designing and optimizing future space manipulators, which may provide valuable references for design and thermal control of the space manipulator.展开更多
基金the National Natural Science Foundation of China(Nos.11132001,11272202 and 11472171)the Key Scientific Project of Shanghai Municipal Education Commission(No.14ZZ021)the Natural Science Foundation of Shanghai(No.14ZR1421000)
文摘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.
文摘The kinematic accuracy of space manipulator determines whether the spacecraft performs normally or not. Problems pertaining to structural deformation have received increased attention in recent times. In the space manipulator systems, flexible arms and joints can induce drastic dynamic instabilities. In applications such as the space station, kinematic error due to structural deformation can jointly affect the performance characteristics. And it is crucial for accuracy control of space manipulator to establish a precision index. Here we analyze the dynamics characteristic of flexible space manipulator considering the hysteresis of harmonic reducer based on method of nonconstraint boundary modal. For the sake of describing the output accuracy, we integrate the method of analytic hierarchy process(AHP) to establish a comprehensive evaluation index. A numerical simulation is performed to analyze the nonlinear dynamic characteristics of space manipulator with harmonic reducer. With the analysis of accuracy assessment, the relation among the hysteresis angle, rigidity and output accuracy is revealed. Considering the elastic modulus of flexible space manipulator and the hysteresis angle of harmonic reducer, we conduct an evaluation of output characteristics of flexible space manipulator with the proposed comprehensive evaluation index. The accuracy evaluation of output characteristics based on the proposed comprehensive evaluation index is implemented in the initial stage of space manipulator's design, which can not only solve the problems existing in the design but also save cost savings for ground tests. The results can be used in designing and optimizing future space manipulators, which may provide valuable references for design and thermal control of the space manipulator.
