Da F.,Nanjing Automation Research Institute |
Wang X.,Nanjing Southeast University |
Huang H.,Nanjing Southeast University
IEEE Transactions on Instrumentation and Measurement | Year: 2011
A novel phase-unwrapping algorithm is proposed by using interlaced fringe in optical 3-D measurement. In the measurement, a four-step phase-shift method including four sinusoidal fringes with 90° phase shift is used. On top of these four fringes, an interlaced fringe is encoded. In the measurement, all these designed fringes are projected onto the tested object, and fringe images are acquired by charge-coupled device cameras. Then, four fringe-different images with zero-valued fringes can be obtained by subtracting the interlaced fringe image from the other four sinusoidal fringe images; thus, the position and the characteristic of each fringe can be distinguished. Combined with the composition of the encoding interlaced fringe, the order of the fringes can be obtained. The whole process needs only one assistant interlaced fringe image. Experiment result shows that the proposed algorithm can get the 3-D information rapidly and exactly and has more robustness. © 2011 IEEE.
Xiao H.F.,Nanjing Southeast University |
Lan K.,Nanjing Southeast University |
Zhou B.,Nanjing Automation Research Institute |
Zhang L.,Nanjing Southeast University |
Wu Z.,Nanjing Southeast University
IEEE Transactions on Power Electronics | Year: 2015
Low leakage current and high efficiency are two key indexes for transformerless PV grid-connected inverter. The transformerless inverter topologies have superior efficiency thanks to saving transformer, but their semiconductor devices are still on hard-switching state at present. First and foremost, a novel zero-current-transition (ZCT) concept for the single-phase full-bridge transformerless PV grid-connected inverters is presented in this paper. Second, the zero-current turn-off for high-frequency main switches of the inverters and the zero-current turn-on for auxiliary switches added are achieved by introducing two resonant tanks. Furthermore, a family of ZCT transformerless gridconnected inverters with sinusoidal pulse width modulation is deduced. Especially, taking zero-current-transition six-switch fullbridge topology (ZCT-H6-I) as an example, its operation principle, soft-switching conditions, duty cycle constraints, and parameter design procedure of the resonant tank are analyzed in detail. Finally, the validity of the ZCT concept is verified by a ZCT-H6-I prototype rated at 50 kHz, 1 kW. © 2014 IEEE.
Guo L.,Nanjing Automation Research Institute |
Guo L.,Beihang University |
Wen X.-Y.,Nanjing Automation Research Institute
Transactions of the Institute of Measurement and Control | Year: 2011
In this paper, a new anti-disturbance controller is presented for a class of non-linear systems with multiple disturbances. The first part of the disturbance is described by an exogenous model and the second part represents an uncertain variable bounded by a given function. A new non-linear disturbance observer is designed to estimate the composite disturbances. Then, a hierarchical control strategy consisting of disturbance-observer-based control and a robust adaptive controller is presented to achieve the anti-disturbance performance. A stability analysis for both the error estimation systems and the composite closed-loop system is provided. Finally, the approach is applied to a missile control system to show the efficiency of the approach. © 2010 The Institute of Measurement and Control.
Li X.,Shanghai Municipal Electric Power Company |
Da F.,Nanjing Automation Research Institute
Image and Vision Computing | Year: 2012
This paper presents an efficient 3D face recognition method to handle facial expression and hair occlusion. The proposed method uses facial curves to form a rejection classifier and produce a facial deformation mapping and then adaptively selects regions for matching. When a new 3D face with an arbitrary pose and expression is queried, the pose is normalized based on the automatically detected nose tip and the principal component analysis (PCA) follows. Then, the facial curve in the nose region is extracted and used to form the rejection classifier which quickly eliminates dissimilar faces in the gallery for efficient recognition. Next, six facial regions which cover the face are segmented and curves in these regions are used to map facial deformation. Regions used for matching are automatically selected based on the deformation mapping. In the end, results of all the matching engines are fused by weighted sum rule. The approach is applied on the FRGC v2.0 dataset and a verification rate of 96.0% for ROC III is achieved as a false acceptance rate (FAR) of 0.1%. In the identification scenario, a rank-one accuracy of 97.8% is achieved. © 2012 Elsevier B.V.
Ji W.,Jiangsu University |
Li Q.,Nanjing Automation Research Institute |
Xu B.,Jiangsu University |
Zhao D.,Jiangsu University |
Fang S.,Nanjing Automation Research Institute
Aerospace Science and Technology | Year: 2011
The line of sight (LOS) stabilization control based on gyro stabilized platform is required to isolate the LOS from the disturbance and vibration of carrier and ensure pointing and tracking for target in electro-optical tracking system. A composite adaptive fuzzy proportional-integral-derivative (PID) control with hysteresis-band switching is developed to achieve real-time and high stabilization precision for this nonlinear uncertainty servo system. First of all, in the adaptive fuzzy controller, the pre-designed self-tuning factors are able to modify the parameters of fuzzy controller online, and a new learning algorithm of fuzzy rules modifier is proposed to adjust control efforts. Then, an improved PID controller is chosen to restrain motor saturation and eliminate the static error originated from the fuzzy controller, and fulfill non-error control. The hysteresis-band switching strategy is given to deal with jitter caused by single-point switching condition. The experimental results in four-axis servo turntable show that the proposed method can achieve nice control performance and is proved to be effective in bating carrier disturbances within the scope of definite noise and sensitivity to acceleration. Crown Copyright © 2010 Published by Elsevier Masson SAS. All rights reserved.
Da F.,Nanjing Automation Research Institute |
Sui Y.,Nanjing Automation Research Institute
Machine Vision and Applications | Year: 2011
An algorithm based on binocular stereo vision is proposed to generate 3D (three-dimensional) dense points cloud model of the human face. A two-step matching strategy from sparse to dense is developed. Firstly, an improved seeds-growing algorithm is utilized to acquire sparse matching of high confidence. Secondly, based on the control points method and piecewise dynamic programming, the dense matching is completed. Experimental results show that the proposed algorithm can produce smooth and dense 3D points cloud model of the human face. © Springer-Verlag 2010.
Li X.-L.,Nanjing Automation Research Institute |
Da F.-P.,Nanjing Automation Research Institute
Zidonghua Xuebao/ Acta Automatica Sinica | Year: 2010
A rapid method for 3D face recognition based on rejection algorithm is proposed. First, the automatically segmented face with a different pose is normalized by means of principal component analysis (PCA), and transformed into the uniform pose coordinate system. Then, the central profile is extracted and matched based on the least trimmed square Hausdorff distance (LTS-HD) to form a rejection classifier which can eliminate a large number of candidate faces. Finally, the remaining faces are verified using a novel region-based iterative closest point (ICP) algorithm, and the result of the recognition is obtained. The simulation experiment on FRGC V2.0 database demonstrates that the proposed method is simple, efficient, and robust. © 2010 Acta Automatica Sinica. All rights reserved.
Ma L.,Nanjing Automation Research Institute |
Da F.,Nanjing Automation Research Institute
International Journal of Robust and Nonlinear Control | Year: 2010
In this paper, the exponential ℋ∞ filter design problem is investigated for a general class of stochastic time-varying delay system with Markovian jumping parameters. The stochastic uncertainties appear in both the dynamic and the measurement equations and the state delay is assumed to be time-varying. Attention is focused on the design of mean-square exponentially stable and Markovian jump filter such that the filtering error systems are mean-square exponentially stable and the estimation error satisfies a given ℋ∞ performance. By introducing some slack matrix variables, delay-dependent sufficient conditions for the solvability of the above problem are presented in terms of linear matrix inequalities (LMIs). In addition, the decay rate can be a given positive value without any other constraints. When the proposed LMIs are feasible, an explicit expression of the desired ℋ∞ filter can be given. A numerical example is provided to illustrate the effectiveness of the proposed design approach. Copyright © 2009 John Wiley & Sons, Ltd.
Han P.-Y.,Nanjing Automation Research Institute |
Da F.-P.,Nanjing Automation Research Institute |
Gai S.-Y.,Nanjing Automation Research Institute
Guangdianzi Jiguang/Journal of Optoelectronics Laser | Year: 2010
A rapid color structured light 3D measurement technique is proposed. Based on the principle of gray code, a novel color coding method using 6 easily distinguished colors is designed. An exclusive sequence of encoded color stripes is presented, whose beginning position of the periods can be discretionary and the inter-symbol interference is avoided. Furthermore, the decoding process is facile. The traditional three-phase shifting is replaced by three-colors phase shifting. By using two color structured light images, 3D shape information can be obtained with higher speed and precision. Experimental results show that the proposed color structured light 3D shape measurement method is effective.
Measuring instruments, namely, gasometers, instruments for measuring length, calipers for measuring trees, coordinate measuring machines, electronic-based instruments for measuring environmental parameters including humidity, mold, bacteria, air quality and water quality, level measuring machines, measuring and control devices for air conditioning technology, measuring tapes; Measuring apparatus, namely, bevels, clamp meters for measuring electricity, distance measuring apparatus.