Duan Z.,National University of Defense Technology |
Duan Z.,Science and Technology on Aerospace Intelligent Control Laboratory |
Lin H.,National University of Defense Technology |
Lin H.,Science and Technology on Aerospace Intelligent Control Laboratory |
And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016
Correlation imaging experiments correlate the outputs from two photodetectors. The image can be obtained by calculating the correlation function between results of two detectors. To reconstruct image of the object, many frames of different speckles are required. Therefore, the speed of correlation imaging is strongly limited by the speed of modulation of the light field. Usually, we use Spatial Light Modulator (SLMï1/4‰ to load different random phase at different positions of a plane-wave light field. The refresh rate of the speckle fields is thus limited by the surface refresh rate of SLM. However, the response speed of each pixel when we control it independently is far greater than the refresh rate of the whole surface. Based on this fact, we propose to modulate each pixel independently with different sinusoidal signals, in order to improve the refresh rate of speckle field. To generate randomly fluctuations, the frequencies of different modulation signals are selected to be coprime. At the same time, we can know in advance the intensity distribution of the speckle field in every frame, since we know the phase of each pixel when every pulse light modulated by the SLM. © 2016 SPIE.
Liu X.,China Aerospace Science and Technology Corporation |
Liu X.,Science and Technology on Aerospace Intelligent Control Laboratory |
Wang Y.,Beihang University |
Huang W.,China Aerospace Science and Technology Corporation |
And 2 more authors.
International Journal of Aerospace Engineering | Year: 2015
This paper presents a novel robust attack angle control approach, which can effectively suppress the impacts from system uncertainties and servo-loop dynamics. A second-order linear model of electromechanical servo loop is considered in the modeling and design processes. With regard to the block-structure models facing attack angle control, the multiple robust surfaces and dynamic surface control (DSC) approaches are both employed. By means of Lyapunov function method, the stability conditions of attack angle control systems are, respectively, given without/with considering the servo-loop dynamics in design process. Computer simulation results present that, compared with the attack angle control scheme which does not consider the servo-loop dynamics in design process, the proposed scheme can guarantee that the whole attack angle control system possesses the better comprehensive performances. Moreover, it is easy to be realized in engineering application. © 2015 Xiaodong Liu et al.
Liu X.-D.,China Aerospace Science and Technology Corporation |
Liu X.-D.,Science and Technology on Aerospace Intelligent Control Laboratory |
Huang W.-W.,China Aerospace Science and Technology Corporation |
Huang W.-W.,Science and Technology on Aerospace Intelligent Control Laboratory |
And 3 more authors.
Yuhang Xuebao/Journal of Astronautics | Year: 2015
Aiming at the complicated nonlinearities, high uncertainties and strong couplings of hypersonic vehicle, a nonlinear attitude control method is put forward. According to the attitude motion equations of unpowered hypersonic vehicle, a nonlinear design model for the attitude control is established. With regard to a class of nonlinear system, a dynamic inversion control (DIC) based on extended state observer (ESO) is proposed and then applied to the attitude control of hypersonic vehicle by using dynamic surface control (DSC) approach. Simulation results show that, the chosen vehicle designed by using the proposed control scheme can track the angle position commands more quickly and accurately, compared with the other DSC scheme based on traditional DIC. Furthermore, it also possesses stronger robustness against system uncertainties. © 2015, Editorial Dept. of JA. All right reserved.