Huang J.,University of Victoria |
Shi Y.,University of Victoria |
Zhang X.,University of Victoria |
Zhang X.,Luoyang Optoelectronic Technology Development Center
International Journal of Adaptive Control and Signal Processing | Year: 2014
This paper investigates the active fault tolerant control problem via the H∞ state feedback controller. Because of the limitations of Markov processes, we apply semi-Markov process in the system modeling. Two random processes are involved in the system: the failure process and the fault detection process. Therefore, two corresponding semi-Markov processes are integrated in the closed-loop system model. This framework can generally accommodate different types of system faults, including the randomly happening sensor faults and actuator faults. A controller is designed to guarantee the closed-loop system stability with a prescribed noise/disturbance attenuation level. The controller can be readily solved by using convex optimization techniques. A vertical take-off and landing vehicle example with actuation faults is used to demonstrate the effectiveness of the proposed technique. © 2013 John Wiley & Sons, Ltd.
Wang S.,Luoyang Institute of Electro optical Equipment |
Wu M.,Luoyang Optoelectronic Technology Development Center |
Xie Y.,Luoyang Institute of Electro optical Equipment |
Xie Y.,Science and Technology on Electro optic Control Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014
To overcome the difficulty in segmenting moving objects from a video sequence taken by a freely moving camera, we propose a new segmentation cue based on a joint spatial-color representation for the foreground and background appearances. Given the segmentation result in the previous frame, two sample sets can be extracted for foreground and background, respectively. We transform the spatial locations of the samples in the two sets towards the current frame, then use these transformed samples to evaluate the foreground and background likelihood maps, and combine these maps to form a likelihood ratio map which is further exploited as a segmentation cue and integrated into a conditional random field energy function. The total conditional random field energy is minimized by the graph cut, leading to a binary mask of moving objects for each video frame. We validate the proposed segmentation cue using several video sequences taken by hand-held cameras in outdoor urban scenes and the results show the effiency of the segmentation cue.
Zhang L.,Luoyang Optoelectronic Technology Development Center |
Chen H.,Luoyang Optoelectronic Technology Development Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011
Dual-band IR imaging detector can be responsive to two correlated spectrum of the target and the flare. With the equivalent temperature of the target and the flare, the radiation characteristic of the target and the flare is simulated by MATLAB which is based on Plank's law of the blackbody radiation, and the SWIR/MWIR spectrum is chose where the IR radiation is the largest difference between the target and the flare. The theoretical calculation procedure is designed according to the transform flow of the IR radiation. First we calculate the responsive results of InSb IRFPA to the cavity blackbody and the extended area blackbody, because of the simulated results are consistent with the tested results, the simulation procedure is of practical. Then consideration of the HgCdTe 128×128 detector with pixels are stacked, the performance parameters of HgCdTe SW/MW dual-band IR imaging detector are simulated with MATLAB procedures, the purpose of distinguish the target from the flare with image and dual-band ratio can be reached, and the two benefit conclusions can be achieved. © 2011 SPIE.
Zhao Y.,Luoyang Optoelectronic Technology Development Center |
Gao J.,Luoyang Optoelectronic Technology Development Center |
Wang Y.,Luoyang Optoelectronic Technology Development Center |
Quan Y.,Xidian University
Proceedings of 2012 5th Global Symposium on Millimeter-Waves, GSMM 2012 | Year: 2012
A method of Doppler frequency rate estimation is proposed to deal with motion compensations for missile-borne SAR imaging. Working in burst SAR mode, Map Drift method is improved to satisfy the complicated condition of missile-borne motion, such as PRF up to ten kHz and maneuvering speed up to 3 Ma. Appropriate block size of azimuth data sequence and correlative operation should be chosen according to performance analysis, which is shown in this paper. Experimentations proved the validity of this method. © 2012 IEEE.
Fan H.,Luoyang Optoelectronic Technology Development Center |
Yang J.,Northwestern Polytechnical University |
Zhu X.,Northwestern Polytechnical University
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2013
The phased array radar seeker is at present the top choice in the new generation air to air missiles guidance system, and beam stabilization is the first problem to be solved in this application. This paper proposes a beam stabilization algorithm for phased array radar seeker based on the theory of the invariability of beam orientation in inertial space. It simulates and analyzes the main factors that affect the isolation performance of a phased array radar seeker. The simulation results indicate that this algorithm possesses good performance and high engineering feasibilty. They also demonstrate that decreasing the cycle of the rate gyroscope's data and the beam control period as well as introducing a transmission delay compensation algorithm of the gyroscope will significantly improve the isolation performance of the seeker.