The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Philippe Paillou - One of the best experts on this subject based on the ideXlab platform.
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Trinocular stereovision by generalized hough transform
Pattern Recognition, 1996Co-Authors: Philippe PaillouAbstract:Abstract In this paper we generalize the Hough transform to match the edge segments in trinocular stereovision and determine the Parameters of the segments in 3-D (three-dimensional) space. We show that the corresponding segment triplet candidates can be detected by a generalized Hough transform in the Parameter Plane (ω, θ) which characterizes the 3-D segment orientation. These triplets can then be verified and the position Parameters of the 3-D segments can be detected by a Hough transform in the Parameter Plane (Y, Z). So the matching of geometric primitives in trinocular stereovision images can be found by the cascade of searchings in two 2-D Parameters spaces only. Experimental results are satisfactory. Our method shows the following advantages: (1) trinocular stereovision image matching is transformed into searching in 2-D Parameter spaces, which much reduces the computational complexity. (2) Matching can be carried out completely in parallel. (3) No a priori similarity between images is needed, so very different views can be used, which improves the precision of 3-D reconstruction. (4) It is very efficient to solve false targets. (5) Our method gives good results even for partially hidden segments.
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Trinocular stereovision by matching in Parameter space
International Conference on Intelligent Manufacturing, 1995Co-Authors: Philippe PaillouAbstract:In this paper, we generalize the Hough transform to match the edge segments in trinocular stereovision and to determine the Parameters of the segments in 3-D space. We show that the corresponding segment triplet candidates can be detected by a Hough transform in the Parameter Plane ((theta) , (phi) ) which characterizes the 3-D segment orientation. These triplets can then be verified, and the position Parameters of the 3-D segments can be detected by a Hough transform in the Parameter Plane (Y, Z). So the matching of geometric primitives in trinocular stereovision images can be found by the cascade of searchings in two 2-D Parameter spaces only. Experimental results are satisfactory. Our method shows the following advantages: (1) Trinocular stereovision image matching is transformed into searching in 2-D Parameter spaces, which much reduces the computational complexity. (2) Matching can be done completely in parallel. (3) No a priori similarity between images is needed, so very different views can be used, which improves the precision of 3-D reconstruction. (4) It is very efficient to solve false targets. (5) Our method gives good results even for partially hidden segments.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Xiangfeng Gou - One of the best experts on this subject based on the ideXlab platform.
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bifurcation and evolution of a forced and damped duffing system in two Parameter Plane
Nonlinear Dynamics, 2018Co-Authors: Jianfei Shi, Yanlong Zhang, Xiangfeng GouAbstract:A general method to calculate multi-Parameter bifurcation diagram in the Parameter space is designed based on top Lyapunov exponent and Floquet multiplier to study the effect of different combinations of system Parameters on the system’s dynamics. Bifurcation and chaos of the forced and damped Duffing system in two-Parameter Plane are investigated by using the method designed in this work. The correlation and matching laws of the Duffing system between dynamic performance and system Parameters are analyzed. The effect of different types of bifurcation curves on the bifurcating of coexisting attractors is investigated according to basins of attraction, bifurcation diagrams, top Lyapunov exponent spectrums, phase portraits, Poincare maps, and Floquet multipliers. The evolution of various bifurcation curves and codimension-two bifurcation in the parametric Plane is studied as well. Coexisting attractors are found in the Parameter Plane. The results indicate that the different bifurcating curves are selective for the bifurcation of coexisting attractors. Both the pitchfork bifurcation curve and the period-doubling bifurcation curve just change the stability of some of the coexisting attractors, but have no effect on the stability of the other part of the attractors. The saddle-node bifurcation curve has an effect on the stability of all the coexisting attractors. A series of period-doubling bifurcation curves and codimension-two bifurcation points lead to chaos existence region in two-Parameter Plane. The special evolution of bifurcation points and bifurcation curves in two-Parameter Plane with the change of the system Parameter is observed. The codimension-two bifurcation points and bifurcation curves play an important role in understanding nonlinear dynamics of the system in the parametric Plane. The work in this study emphasizes the importance of the different combinations of system Parameters on the system dynamics.
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bifurcation and chaos analysis of spur gear pair in two Parameter Plane
Nonlinear Dynamics, 2015Co-Authors: Xiangfeng Gou, Lingyun Zhu, Dailin ChenAbstract:A developed algorithm is designed based on the simple cell mapping method and escape time algorithm to examine every state cell and the dynamic characteristics of the multi-Parameter coupling in torsion-vibration gear system. Two different types of bifurcation caused by the intersection of the period-doubling bifurcation curves are researched by analyzing the distribution map and the bifurcation diagram of system’s dynamic characteristic in the Parameter Plane, $$\omega -F$$ . The occurrence processes of periodic bubbles and saltatory periodic bifurcation are studied. The stationary solution and its phase trajectory of the fractal of the periodic motion attractor boundary are researched too. The sufficient condition of the fractal structure of the periodic attractor domain is achieved. Homoclinic or heteroclinic trajectory in phase space is found caused by the intersection of the different periodic motion trajectories in non-smooth system.
Yuanjay Wang - One of the best experts on this subject based on the ideXlab platform.
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graphical computation of gain and phase margin specifications oriented robust pid controllers for uncertain systems with time varying delay
Journal of Process Control, 2011Co-Authors: Yuanjay WangAbstract:Abstract This paper proposes a novel graphical method to compute all feasible gain and phase margin specifications-oriented robust PID controllers to stabilize uncertain control systems with time-varying delay. A virtual gain-phase margin tester compensator is incorporated to guarantee the concerned system with certain robust safety margins. The complex Kharitonov theorem is used to characterize the parametric uncertainties of the considered system and is exploited as a stability criterion for the Hurwitz property of a family of polynomials with complex coefficients varying within given intervals. The coefficients of the characteristic equation are overbounded and eight vertex Kharitonov polynomials are derived to perform stability analysis. The stability equation method and the Parameter Plane method are exploited to portray constant gain margin and phase margin boundaries. The feasible controllers stabilizing every one of the eight vertex polynomials are identified in the Parameter Plane by taking the overlapped region of the plotted boundaries. The overlapped region of the useful region of each vertex polynomial is the Kharitonov region, which represents all the feasible specifications-oriented robust PID controller gain sets. Variations of the Kharitonov region with respect to variations of the derivative gain are extensively studied. The way to select representative points from the Kharitonov region for designing robust controllers is suggested. Finally, three illustrative examples with computer simulations are provided to demonstrate the effectiveness and confirm the validity of the proposed methodology. Based on the pre-specified gain and phase margin specifications, a non-conservative Kharitonov region can be graphically identified directly in the Parameter Plane for designing robust PID controllers.
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characterization and quenching of friction induced limit cycles of electro hydraulic servovalve control systems with transport delay
Isa Transactions, 2010Co-Authors: Yuanjay WangAbstract:This paper develops a systematic and straightforward methodology to characterize and quench the friction-induced limit cycle conditions in electro-hydraulic servovalve control systems with transport delay in the transmission line. The nonlinear friction characteristic is linearized by using its corresponding describing function. The delay time in the transmission line, which could accelerate the generation of limit cycles is particularly considered. The stability equation method together with Parameter Plane method provides a useful tool for the establishment of necessary conditions to sustain a limit cycle directly in the constructed controller coefficient Plane. Also, the stable region, the unstable region, and the limit cycle region are identified in the Parameter Plane. The Parameter Plane characterizes a clear relationship between limit cycle amplitude, frequency, transport delay, and the controller coefficients to be designed. The stability of the predicted limit cycle is checked by plotting stability curves. The stability of the system is examined when the viscous gain changes with respect to the temperature of the working fluid. A feasible stable region is characterized in the Parameter Plane to allow a flexible choice of controller gains. The robust prevention of limit cycle is achieved by selecting controller gains from the asymptotic stability region. The predicted results are verified by simulations. It is seen that the friction-induced limit cycles can be effectively predicted, removed, and quenched via the design of the compensator even in the case of viscous gain and delay time variations unconditionally.
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Limit cycle analysis of electro-hydraulic control systems with friction and transport delay
Proceedings of the 3rd World Congress on Intelligent Control and Automation (Cat. No.00EX393), 2000Co-Authors: Y.j. Huang, Yuanjay WangAbstract:A graphical prediction method is developed to effectively predict the possibilities of the existence of limit cycles for a widely used electro-hydraulic control system subject to nonlinear friction force. The nonlinearity is linearized by its corresponding describing function. Then the stability equation method accompanied by a Parameter Plane method provides a useful tool for the establishment of necessary conditions to sustain a limit cycle. Further, the stability analysis for systems subject to an uncertain transport delay time is considered. Simulations verify the accuracy of the prediction method.
Hung I. Chin - One of the best experts on this subject based on the ideXlab platform.
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Limit cycle analysis of nonlinear sampled-data systems by gain-phase margin approach
Journal of the Franklin Institute, 2005Co-Authors: Jau-woei Perng, Hung I. ChinAbstract:This work analyzes the limit cycle phenomena of nonlinear sampled-data systems by applying the methods of gain–phase margin testing, the M-locus and the Parameter Plane. First, a sampled-data control system with nonlinear elements is linearized by the classical method of describing functions. The stability of the equivalent linearized system is then analyzed using the stability equations and the Parameter Plane method, with adjustable Parameters. After the gain–phase margin tester has been added to the forward open-loop system, exactly how the gain–phase margin and the characteristics of the limit cycle are related can be elicited by determining the intersections of the M-locus and the constant gain and phase boundaries. A concise method is presented to solve this problem. The minimum gain–phase margin of the nonlinear sampled-data system at which a limit cycle can occur is investigated. This work indicates that the procedure can be easily extended to analyze the limit cycles of a sampled-data system from a continuous-data system cases considered in the literature. Finally, a sampled-data system with multiple nonlinearities is illustrated to verify the validity of the procedure.
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Gain-phase margin analysis of dynamic fuzzy control systems
IEEE transactions on systems man and cybernetics. Part B Cybernetics : a publication of the IEEE Systems Man and Cybernetics Society, 2004Co-Authors: Jau-woei Perng, Hung I. Chin, Tsu-tian LeeAbstract:In this paper, we apply some effective methods, including the gain-phase margin tester, describing function and Parameter Plane, to predict the limit cycles of dynamic fuzzy control systems with adjustable Parameters. Both continuous-time and sampled-data fuzzy control systems are considered. In general, fuzzy control systems are nonlinear. By use of the classical method of describing functions, the dynamic fuzzy controller may be linearized first. According to the stability equations and Parameter Plane methods, the stability of the equivalent linearized system with adjustable Parameters is then analyzed. In addition, a simple approach is also proposed to determine the gain margin and phase margin which limit cycles can occur for robustness. Two examples of continuous-time fuzzy control systems with and without nonlinearity are presented to demonstrate the design procedure. Finally, this approach is also extended to a sampled-data fuzzy control system.
Miroslav R Matausek - One of the best experts on this subject based on the ideXlab platform.
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pid controller tuning based on the classification of stable integrating and unstable processes in a Parameter Plane
2012Co-Authors: Tomislav B Sekara, Miroslav R MatausekAbstract:Classification of processes and tuning of the PID controllers is initiated by Ziegler and Nichols (1942). This methodology, proposed seventy years ago, is still actual and inspirational. Process dynamics characterization is defined in both the time and frequency domains by the two Parameters. In the time domain, these Parameters are the velocity gain Kv and dead-time L of an Integrator Plus Dead-Time (IPDT) model GZN(s)=Kvexp(-Ls)/s, defined by the reaction curve obtained from the open-loop step response of a process. In the frequency domain these Parameters are the ultimate gain ku and ultimate frequency ωu, obtained from oscillations of the process in the loop with the proportional controller k=ku. The relationship between Parameters in the time and frequency domains is determined by Ziegler and Nichols as
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classification of dynamic processes and pid controller tuning in a Parameter Plane
Journal of Process Control, 2011Co-Authors: Tomislav B Sekara, Miroslav R MatausekAbstract:Abstract A quadruplet, defined by the ultimate frequency ωu, the ultimate gain ku, the angle φ of the tangent to the Nyquist curve at the ultimate frequency and the gain Gp(0), is sufficient for classification of a large class of stable processes, processes with oscillatory dynamics, integrating and unstable processes Gp(s). From the model defined by the above quadruplet, a two Parameter model Gn(sn) is obtained by the time and amplitude normalizations. Two Parameters of Gn(sn), the normalized gain ρ and the angle φ, are coordinates of the classification ρ–φ Parameter Plane. Model Gn(sn) is used to obtain the desired closed-loop system performance/robustness tradeoff in the desired region of the classification Plane. Tuning procedures and tuning formulae are derived guaranteeing almost the same performance/robustness tradeoff as obtained by the optimal PID controller, applied to Gp(s) classified to the same region of the classification Plane. Validity of the proposed method is demonstrated on a test batch consisting of stable processes, processes with oscillatory dynamics, integrating and unstable processes, including dead-time.
