Articles de revues sur le sujet « Controller normal form »
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Khajepour, A., M. F. Golnaraghi et K. A. Morris. « MODAL COUPLING CONTROLLER DESIGN USING NORMAL FORM METHOD, PART II : CONTROL ». Journal of Sound and Vibration 205, no 5 (septembre 1997) : 671–88. http://dx.doi.org/10.1006/jsvi.1997.1073.
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Khajepour, A., M. F. Golnaraghi et K. A. Morris. « MODAL COUPLING CONTROLLER DESIGN USING A NORMAL FORM METHOD, PART I : DYNAMICS ». Journal of Sound and Vibration 205, no 5 (septembre 1997) : 657–70. http://dx.doi.org/10.1006/jsvi.1997.1072.
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Kang, Wei, et Arthur J. Krener. « Extended Quadratic Controller Normal Form and Dynamic State Feedback Linearization of Nonlinear Systems ». SIAM Journal on Control and Optimization 30, no 6 (novembre 1992) : 1319–37. http://dx.doi.org/10.1137/0330070.
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Du, Wenju, Yandong Chu, Jiangang Zhang, Yingxiang Chang, Jianning Yu et Xinlei An. « Control of Hopf Bifurcation in Autonomous System Based on Washout Filter ». Journal of Applied Mathematics 2013 (2013) : 1–16. http://dx.doi.org/10.1155/2013/482351.
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In order to further understand a Lorenz-like system, we study the stability of the equilibrium points and the existence of Hopf bifurcation by center manifold theorem and normal form theory. More precisely, we designed a washout controller such that the equilibriumE0undergoes a controllable Hopf bifurcation, and by adjusting the controller parameters, we delayed Hopf bifurcation phenomenon of the equilibriumE+. Besides, numerical simulation is given to illustrate the theoretical analysis. Finally, two possible electronic circuits are given to realize the uncontrolled and the controlled systems.
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Rabbani, Muhammad Junaid, et Attaullah Y. Memon. « Trajectory Tracking and Stabilization of Nonholonomic Wheeled Mobile Robot Using Recursive Integral Backstepping Control ». Electronics 10, no 16 (18 août 2021) : 1992. http://dx.doi.org/10.3390/electronics10161992.
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In this paper, a generalized nontriangular normal form is presented to facilitate designing a recursive integral backstepping control for the class of underactuated nonholonomic systems, i.e., wheeled mobile robots (WMRs) that perform posture stabilization and trajectory tracking in environments without obstacles. Based on the differential geometry theory, we develop a multiple input multiple output (MINO) generalization of normal form using the input-output feedback linearization technique. Then, the change of variables (diffeomorphism) transform the state-space model of WMR, incorporating both kinematic and dynamic models into nontriangular normal form. As a result, the system dynamics can be represented as internal and external dynamics. The nonlinear internal dynamics of WMR pose serious challenges to design a suitable controller due to its internal dynamics being not minimum phase and non-strict feedback form structure. The proposed backstepping controller is designed in two steps. First, a standard integral backstepping controller is designed to stabilize the robot’s orientation angle. Then, a recursive integral backstepping control technique is applied to achieve asymptotic convergence of position error to zero. Hence, both asymptotic posture stabilization and trajectory tracking are achieved in semi-global regions, except the nonzero initial condition of the orientation angle. The asymptotic stability of the entire closed-loop system is shown using the Lyapunov criteria.
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Lozovanu, Dmitrii, et Stefan Pickl. « On the Existence and Determining Stationary Nash Equilibria for Switching Controller Stochastic Games ». Contributions to Game Theory and Management 14 (2021) : 290–301. http://dx.doi.org/10.21638/11701/spbu31.2021.21.
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In this paper we consider the problem of the existence and determining stationary Nash equilibria for switching controller stochastic games with discounted and average payoffs. The set of states and the set of actions in the considered games are assumed to be finite. For a switching controller stochastic game with discounted payoffs we show that all stationary equilibria can be found by using an auxiliary continuous noncooperative static game in normal form in which the payoffs are quasi-monotonic (quasi-convex and quasi-concave) with respect to the corresponding strategies of the players. Based on this we propose an approach for determining the optimal stationary strategies of the players. In the case of average payoffs for a switching controller stochastic game we also formulate an auxiliary noncooperative static game in normal form with quasi-monotonic payoffs and show that such a game possesses a Nash equilibrium if the corresponding switching controller stochastic game has a stationary Nash equilibrium.
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Stepnova, A. I., S. M. Stepanov, V. V. Borsoeva et V. A. Borsoev. « Analysis of effectiveness of the program of joined air traffic controlles and pilotes training ». Civil Aviation High Technologies 22, no 5 (28 octobre 2019) : 32–42. http://dx.doi.org/10.26467/2079-0619-2019-22-5-32-42.
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Training of cadets-air traffic controllers and cadets-pilots is an integral part of the training, which allows you to form the skills of quick and correct decision-making in different types of situations. For the air traffic controller, these are exercises to solve conflict situations with aircraft in the area of their responsibility, solving problems in normal flight conditions, in unfavorable atmospheric conditions and in the non-routine situations in flight. For the pilots, solutions to the problems are reduced to the rapid decisionmaking on aircraft control in normal flight conditions, adverse atmospheric conditions and non-routine situations in flight. As you know, the work of air traffic controllers is associated with the work of pilots, but training in educational institutions takes place separately, resulting in gaps in knowledge of the specifics of the adjacent specialty, and, eventually, leads to errors. Optimization of the educational process is currently an urgent task. The program of joint training can act as an optimization tool. The program enables you to collaboratively practice the skills of fast decision-making, clearly to learn the specifics of the related specialties that will allow you to create a complete picture of the air situation. The program of joint training implies the joint operational logic simulator that combines two simulators. For the air traffic controller, this is a separate airspace area in the form of a sector, for the pilot it is the cockpit. Thus, the solution to the problems occurs sequentially from the air traffic controller to the pilot and vice versa, and the controller has the ability to observe the algorithm of the pilot's actions, and the pilot is able to monitor the algorithm of the controller's actions.
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Zhang, Zizhen, et Huizhong Yang. « Hopf Bifurcation Control in a Delayed Predator-Prey System with Prey Infection and Modified Leslie-Gower Scheme ». Abstract and Applied Analysis 2013 (2013) : 1–11. http://dx.doi.org/10.1155/2013/704320.
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Hopf bifurcation of a delayed predator-prey system with prey infection and the modified Leslie-Gower scheme is investigated. The conditions for the stability and existence of Hopf bifurcation of the system are obtained. The state feedback and parameter perturbation are used for controlling Hopf bifurcation in the system. In addition, direction of Hopf bifurcation and stability of the bifurcated periodic solutions of the controlled system are obtained by using normal form and center manifold theory. Finally, numerical simulation results are presented to show that the hybrid controller is efficient in controlling Hopf bifurcation.
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Zhang, Yandong, et S. C. Sinha. « Development of a Feedback Linearization Technique for Parametrically Excited Nonlinear Systems via Normal Forms ». Journal of Computational and Nonlinear Dynamics 2, no 2 (8 décembre 2006) : 124–31. http://dx.doi.org/10.1115/1.2447190.
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The problem of designing controllers for nonlinear time periodic systems via feedback linearization is addressed. The idea is to find proper coordinate transformations and state feedback under which the original system can be (exactly or approximately) transformed into a linear time periodic control system. Then a controller can be designed to guarantee the stability of the system. Our approach is designed to achieve local control of nonlinear systems with periodic coefficients desired to be driven either to a periodic orbit or to a fixed point. The system equations are represented by a quasi-linear system containing nonlinear monomials with periodic coefficients. Using near identity transformations and normal form theory, the original close loop problem is approximately transformed into a linear time periodic system with unknown gains. Then by using a symbolic computation method, the Floquet multipliers are placed in the desired locations in order to determine the control gains. We also give the sufficient conditions under which the system is feedback linearizable up to the rth order.
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Han, Xiaobao, Zhenbao Liu, Huacong Li et Xianwei Liu. « Output feedback controller design for polynomial linear parameter varying system via parameter-dependent Lyapunov functions ». Advances in Mechanical Engineering 9, no 2 (février 2017) : 168781401769032. http://dx.doi.org/10.1177/1687814017690327.
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This article presents a new output feedback controller design method for polynomial linear parameter varying model with bounded parameter variation rate. Based on parameter-dependent Lyapunov function, the polynomial linear parameter varying system controller design is formulated into an optimization problem constrained by parameterized linear matrix inequalities. To solve this problem, first, this optimization problem is equivalently transformed into a new form with elimination of coupling relationship between parameter-dependent Lyapunov function, controller, and object coefficient matrices. Then, the control solving problem was reduced to a normal convex optimization problem with linear matrix inequalities constraint on a newly constructed convex polyhedron. Moreover, a parameter scheduling output feedback controller was achieved on the operating condition, which satisfies robust performance and dynamic performances. Finally, the feasibility and validity of the controller analysis and synthesis method are verified by the numerical simulation.
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Rosales, Enrique, Chrystiano Araújo, Jafet Rodriguez, Nicholas Vining, Dongwook Yoon et Alla Sheffer. « AdaptiBrush ». ACM Transactions on Graphics 40, no 6 (décembre 2021) : 1–15. http://dx.doi.org/10.1145/3478513.3480511.
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Virtual reality drawing applications let users draw 3D shapes using brushes that form ribbon shaped, or ruled-surface, strokes. Each ribbon is uniquely defined by its user-specified ruling length, path, and the ruling directions at each point along this path. Existing brushes use the trajectory of a handheld controller in 3D space as the ribbon path, and compute the ruling directions using a fixed mapping from a specific controller coordinate-frame axis. This fixed mapping forces users to rotate the controller and thus their wrists to change ribbon normal or ruling directions, and requires substantial physical effort to draw even medium complexity ribbons. Since human ability to rotate their wrists continuously is heavily restricted, the space of ribbon geometries users can comfortably draw using these brushes is limited. These brushes can be unpredictable, producing ribbons with unexpectedly varying width or flipped and wobbly normals in response to seemingly natural hand gestures. Our AdaptiBrush ribbon brush system dramatically extends the space of ribbon geometries users can comfortably draw while enabling them to accurately predict the ribbon shape that a given hand motion produces. We achieve this by introducing a novel adaptive ruling direction computation method, enabling users to easily change ribbon ruling and normal orientation using predominantly translational controller, and thus wrist, motion. We facilitate ease-of-use by computing predictable ruling directions that smoothly change in both world and controller coordinate systems, and facilitate ease-of-learning by prioritizing ruling directions which are well-aligned with one of the controller coordinate system axes. Our comparative user studies confirm that our more general and predictable ruling computation leads to significant improvements in brush usability and effectiveness compared to all prior brushes; in a head to head comparison users preferred AdaptiBrush over the next-best brush by a margin of 2 to 1.
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Vanka, Dega Rajaji, et K. Chandra Sekhar. « Power applications for fuel-cell using switching regulators ». Indonesian Journal of Electrical Engineering and Computer Science 15, no 1 (1 juillet 2019) : 71. http://dx.doi.org/10.11591/ijeecs.v15.i1.pp71-79.
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<p><strong> </strong></p>Generally the switch mode power supply input voltage source is constant or shows insignificant little varieties.in any case, when fuel call used input source the last assumption is not valid. A fuel cell stack is give a details of low and not controlled DC output voltage, moreover, when the demanded current increases the output voltage becomes low in a nonlinear form; from now on, suitable controller is required to taken the previously mentioned issues. In this article, a normal current-mode controller is planned to using a joined model for an energy unit stack and a boost converter; besides, the resolving control method increasing the system stability and output voltage regulation.. The proposed energy system utilizes an energy component power (polymer electrolyte film fuel cell) and a boost converter passing on power of 900 W. the proposed controller execution for output voltage regulation by means of closed loop gain estimations and step load changes. What's more, a correlation amongst open-and closed- loop estimations is made, where the controller robustness is tried for vast load varieties and fuel cell stack output voltage changes are shows on simulation results.
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Peng, Miao, Zhengdi Zhang, C. W. Lim et Xuedi Wang. « Hopf Bifurcation and Hybrid Control of a Delayed Ecoepidemiological Model with Nonlinear Incidence Rate and Holling Type II Functional Response ». Mathematical Problems in Engineering 2018 (7 juin 2018) : 1–12. http://dx.doi.org/10.1155/2018/6052503.
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Hopf bifurcation analysis of a delayed ecoepidemiological model with nonlinear incidence rate and Holling type II functional response is investigated. By analyzing the corresponding characteristic equations, the conditions for the stability and existence of Hopf bifurcation for the system are obtained. In addition, a hybrid control strategy is proposed to postpone the onset of an inherent bifurcation of the system. By utilizing normal form method and center manifold theorem, the explicit formulas that determine the direction of Hopf bifurcation and the stability of bifurcating period solutions of the controlled system are derived. Finally, some numerical simulation examples confirm that the hybrid controller is efficient in controlling Hopf bifurcation.
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Zhao, Jian, Xianku Zhang, Yilin Chen et Pengrui Wang. « Using Sine Function-Based Nonlinear Feedback to Control Water Tank Level ». Energies 14, no 22 (13 novembre 2021) : 7602. http://dx.doi.org/10.3390/en14227602.
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This manuscript addresses the feasibility and significance of using a sine function to modify the system error of a normal linear feedback control to achieve more efficient capabilities in terms of energy-saving. The associated mathematic modeling and assessment were demonstrated by presenting a case analysis on the capabilities of controlling water level for a single tank. The principle of robust control and the theories and detailed algorithm of Lyapunov stability were applied to assess the result derived by novel nonlinear feedback in the form of sine function for optimizing the robustness of the PID (Proportional–Integral–Derivative) controller and economizing energy. Two control simulations are compared: nonlinear feedback control using a sine function and conventional fuzzy control. The results reveal that using the nonlinear feedback controller, a reduction of up to 32.9% of the average controlled quantity is achieved, and the performance index is improved by 24.0% with satisfactory robustness. The proposed nonlinear feedback control using a sine function provides simplicity, convenient implementation, and energy efficiency.
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Fang, Chen, Jiang Hong Shi, Kun Yu Li et Zheng Wang. « State Feedback Robust H∞ Control for Generalized Discrete System and Simulation ». Applied Mechanics and Materials 467 (décembre 2013) : 621–26. http://dx.doi.org/10.4028/www.scientific.net/amm.467.621.
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For a class of uncertain generalized discrete linear system with norm-bounded parameter uncertainties, the state feedback robust control problem is studied. One sufficient condition for the solvability of the problem and the state feedback robust controller are obtained in terms of linear matrix inequalities. The designed controller guarantees that the closed-loop systems is regular, causal, stable and satisfies a prescribed norm bounded constraint for all admissible uncertain parameters under some conditions. The result of the normal discrete system can be regarded as a particular form of our conclusion. A simulation example is given to demonstrate the effectiveness of the proposed method.
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Galvan-Colmenares, Sergio, Marco A. Moreno-Armendáriz, José de Jesús Rubio, Floriberto Ortíz-Rodriguez, Wen Yu et Carlos F. Aguilar-Ibáñez. « Dual PD Control Regulation with Nonlinear Compensation for a Ball and Plate System ». Mathematical Problems in Engineering 2014 (2014) : 1–10. http://dx.doi.org/10.1155/2014/894209.
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The normal proportional derivative (PD) control is modified to a new dual form for the regulation of a ball and plate system. First, to analyze this controller, a novel complete nonlinear model of the ball and plate system is obtained. Second, an asymptotic stable dual PD control with a nonlinear compensation is developed. Finally, the experimental results of ball and plate system are provided to verify the effectiveness of the proposed methodology.
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Zhong, Jinghong, Bin Yang, Jianping Li et Renyun Sun. « Automatic parking trajectory tracking control strategy on LQR and PID ». E3S Web of Conferences 360 (2022) : 01095. http://dx.doi.org/10.1051/e3sconf/202236001095.
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This study selects two degree of freedom dynamic model as the research object, and the automatic parking process is analyzed. The longitudinal cascade controller of speed PID and position PID is used to control the longitudinal motion of the vehicle. The lateral tracking controller based on LQR optimal theory is adopted, and the feedforward control is added to form the optimal feedforward LQR controller as the lateral tracking controller. Based on the co-simulation platform of MATLAB/Simulink and CarSim, the function of the designed automatic parking trajectory tracking control strategy is verified. The car test was completed. The ultrasonic sensor, raspberry pie and Arduino were used as the main parts to build an intelligent car test platform to simulate the performance of the designed tracking control strategy in the real vehicle. Software simulation results and vehicle test results showed that the designed control strategy can ensure the path tracking performance of vehicle under normal parking speed, and has good tracking accuracy, real-time performance and vehicle driving stability.
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Xu, Fu Lin, et Su Hua Liu. « Amplitude Control of Limit Cycle in Chua System ». Advanced Materials Research 328-330 (septembre 2011) : 2079–85. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.2079.
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The control of amplitude of limit cycle emerging from the Hopf bifurcation in Chua system under a nonlinear feedback controller is investigated in this paper, Explicit nonlinear control formulae and amplitude approximations in terms of control gains derived from the center manifold theory and normal form reduction present a convenient approach to obtain an effective analytical control and predict the amplitude of limit cycles in Chua system. The calculating simulations indicate that the approximate solutions are in good agreement with the numerical solutions.
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Song, Caiqin, et Guoliang Chen. « Solutions to the matrix equation X − AXB = CY+R and its application ». Transactions of the Institute of Measurement and Control 40, no 3 (1 novembre 2016) : 995–1004. http://dx.doi.org/10.1177/0142331216673422.
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The solution of the nonhomogeneous Yakubovich matrix equation [Formula: see text] is important in stability analysis and controller design in linear systems. The nonhomogeneous Yakubovich matrix equation [Formula: see text], which contains the well-known Kalman–Yakubovich matrix equation and the general discrete Lyapunov matrix equation as special cases, is investigated in this paper. Closed-form solutions to the nonhomogeneous Yakubovich matrix equation are presented using the Smith normal form reduction. Its equivalent form is provided. Compared with the existing method, the method presented in this paper has no limit to the dimensions of an unknown matrix. The present method is suitable for any unknown matrix, not only low-dimensional unknown matrices, but also high-dimensional unknown matrices. As an application, parametric pole assignment for descriptor linear systems by PD feedback is considered.
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Buzoianu, Eugenia, Mariana Moiceanu et Doina Anca Plesca. « Correlation between FeNO value and asthma severity ». Romanian Journal of Pediatrics 63, no 3 (30 septembre 2014) : 249–53. http://dx.doi.org/10.37897/rjp.2014.3.5.
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Objective. The purpose of this study is to assess the correlation between the FeNO (fractional exhaled nitric oxide) value and asthma severity. Material and method. A prospective study including 48 children aged 5 to 18 years, who have been diagnosed with asthma in „Victor Gomoiu” Children Clinical Hospital between May 2012 – November 2013, has been initiated. In the first stage of the study both the diagnosis and the degree of severity of asthma, using GINA 2008 guideline criteria, have been established, and the FeNO value has been measured before beginning any controller therapy. For the persistent asthma forms the controller therapy has been initiated, adapted to provide the controlled asthma status. In the next stage, after GINA 2014 guideline was published, a second classification of asthma, based on the degree of severity, has been performed, by taking into account the treatment step necessary to maintain the controlled asthma status, according to this new guide. Finally the correlation between FeNO value and the degree of asthma severity has been assessed, using first the asthma classification from GINA 2008 guideline and then the asthma classification from GINA 2014 guideline. Results. Among those 48 children included in the study 29 had normal FeNO value and 19 elevated FeNO value. According to GINA 2008 guideline criteria they have been included in the following severity asthma forms: 6 patients intermittent asthma, 27 patients mild persistent asthma, 14 patients moderate persistent asthma and 1 patient severe persistent asthma. According to GINA 2014 guideline criteria 25 patients have been labeled as mild asthma, 22 as moderate asthma and 1 as severe asthma. The statistic assessment of the correlation between asthma severity form according to GINA 2008 guideline and FeNO value provided a value of p = 0,278 and for the correlation between FeNO value and asthma severity form according to GINA 2014 guideline provided a value of p = 0,0468. Conclusion. FeNO value is not correlated with asthma severity as resulted from GINA 2008 guideline classification, but is correlated with asthma severity as resulted from GINA 2014 guideline classification.
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Zhai, Chi, Chunxi Yang et Jing Na. « Bifurcation Control on the Un-Linearizable Dynamic System via Washout Filters ». Sensors 22, no 23 (30 novembre 2022) : 9334. http://dx.doi.org/10.3390/s22239334.
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Information fusion integrates aspects of data and knowledge mostly on the basis that system information is accumulative/distributive, but a subtle case emerges for a system with bifurcations, which is always un-linearizable and exacerbates information acquisition and presents a control problem. In this paper, the problem of an un-linearizable system related to system observation and control is addressed, and Andronov–Hopf bifurcation is taken as a typical example of an un-linearizable system and detailed. Firstly, the properties of a linear/linearized system is upon commented. Then, nonlinear degeneracy for the normal form of Andronov–Hopf bifurcation is analyzed, and it is deduced that the cubic terms are an integral part of the system. Afterwards, the theoretical study on feedback stabilization is conducted between the normal-form Andronov–Hopf bifurcation and its linearized counterpart, where stabilization using washout-filter-aided feedback is compared, and it is found that by synergistic controller design, the dual-conjugate-unstable eigenvalues can be stabilized by single stable washout filter. Finally, the high-dimensional ethanol fermentation model is taken as a case study to verify the proposed bifurcation control method.
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Sheng, Lianchao, Wei Li, Gaifang Xin, Yuqiao Wang, Mengbao Fan et Xuefeng Yang. « Nonlinear Torsional Vibration Analysis and Nonlinear Feedback Control of Complex Permanent Magnet Semidirect Drive Cutting System in Coal Cutters ». Complexity 2019 (20 mai 2019) : 1–14. http://dx.doi.org/10.1155/2019/9359218.
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The semidirect drive cutting transmission system of coal cutters is prone to unstable torsional vibration when the resistance values of its driving permanent magnet synchronous motor (PMSM) are affected by changes in temperatures and tough conditions. Besides, the system has the properties of complex electromechanically coupling such as the coupling between electrical parameters and mechanical parameters. Therefore, in this study, the nonlinear torsional vibration equation was established on the basis of the Lagrange-Maxwell theory. Moreover, in light of the nonlinear dynamic bifurcation theory, the system stability was analyzed by taking the resistance value of power motor as the bifurcation parameter. In addition, the influence of subcritical bifurcation on the torsional vibration was studied by investigating the necessary and sufficient conditions for dynamic Hopf bifurcation and classifying the bifurcation types. At last, in order to suppress destabilizing oscillation induced by Hopf bifurcation, the nonlinear feedback controller was constructed, with the introduction of feedback from the motor velocity as well as the selection of voltage value on the q shaft as the controlled variable. Meanwhile, the three-order normal form and controlling parameters of the system were obtained with the aid of the multiple scales method and the harmonic balance method. In this way, the Hopf bifurcation point was transferred to control the stability of Hopf bifurcation and the amplitude of limit cycle, thus guaranteeing reliable and safe operation of the system. The numerical simulation results indicate that the designed controller boosts an ideal controlling effect.
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Meng, Xin-You, et Yu-Qian Wu. « Bifurcation and Control in a Singular Phytoplankton-Zooplankton-Fish Model with Nonlinear Fish Harvesting and Taxation ». International Journal of Bifurcation and Chaos 28, no 03 (mars 2018) : 1850042. http://dx.doi.org/10.1142/s0218127418500426.
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In this paper, a delayed differential algebraic phytoplankton-zooplankton-fish model with taxation and nonlinear fish harvesting is proposed. In the absence of time delay, the existence of singularity induced bifurcation is discussed by regarding economic interest as bifurcation parameter. A state feedback controller is designed to eliminate singularity induced bifurcation. Based on Liu’s criterion, Hopf bifurcation occurs at the interior equilibrium when taxation is taken as bifurcation parameter and is more than its corresponding critical value. In the presence of time delay, by analyzing the associated characteristic transcendental equation, the interior equilibrium loses local stability when time delay crosses its critical value. What’s more, the direction of Hopf bifurcation and stability of the bifurcating periodic solutions are investigated based on normal form theory and center manifold theorem, and nonlinear state feedback controller is designed to eliminate Hopf bifurcation. Furthermore, Pontryagin’s maximum principle has been used to obtain optimal tax policy to maximize the benefit as well as the conservation of the ecosystem. Finally, some numerical simulations are given to demonstrate our theoretical analysis.
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YOUSEF, HASAN A., MOHAMED HAMDY et MUHAMMAD SHAFIQ. « ADAPTIVE FUZZY-BASED TRACKING CONTROL FOR A CLASS OF STRICT-FEEDBACK SISO NONLINEAR TIME-DELAY SYSTEMS WITHOUT BACKSTEPPING ». International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems 20, no 03 (17 mai 2012) : 339–53. http://dx.doi.org/10.1142/s0218488512500171.
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In this paper, an adaptive fuzzy tracking control is presented for a class of SISO nonlinear strict feedback systems with unknown time delays. The proposed algorithm does not use the backstepping scheme rather it converts the strict-feedback time-delayed system to the normal form. The Mamdani-type fuzzy system is employed to approximate on-line the lumped uncertain system nonlinearity. The developed controller guarantees uniform ultimate boundedness of all signals in the closed-loop system. The designed control law is independent of the time delays and has a simple form with only one adaptive parameter vector needed to be updated on-line. As a result, the proposed control algorithm is considerably simpler than the previous ones based on backstepping. The Lyapunov stability of the fuzzy system parameters and the filtered tracking error is employed to guarantee semiglobal uniform boundedness for the closed loop system. Simulation results are presented to verify the effectiveness of the proposed approach.
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WEN, GUILIN, et DAOLIN XU. « DESIGNING HOPF BIFURCATIONS INTO NONLINEAR DISCRETE-TIME SYSTEMS VIA FEEDBACK CONTROL ». International Journal of Bifurcation and Chaos 14, no 07 (juillet 2004) : 2283–93. http://dx.doi.org/10.1142/s0218127404010679.
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Hopf bifurcations lead to limit circles that exhibit oscillatory behaviors in nonlinear dynamical systems. Building a specified limit circle into nonlinear systems by control enables us to achieve preferred dynamical performance in the systems. This paper reports a general control method for generating a variety of specified Hopf bifurcations at a desired parameter location. The proposed control law is applicable to nonresonance, weak resonance, strong resonance, or degenerate cases. It allows us to flexibly operate and manipulate the control of Hopf bifurcations. The discrete washout filters are used for the feedback controller. The feedback control gains are derived from the critical conditions and stability conditions of Hopf bifurcations by means of the center manifold method and normal form technique. Numerical experiments indicate that the control method is effective.
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Vojtig, Peter. « Fuzzy Reasoning with Tunable t-Operators ». Journal of Advanced Computational Intelligence and Intelligent Informatics 2, no 4 (20 août 1998) : 121–27. http://dx.doi.org/10.20965/jaciii.1998.p0121.
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We introduce a model of fuzzy logic programming in a truth functional fuzzy logic with arbitrary and/or tunable t-operators. This t-operator tuning is the subject of different learning from neural networks to evolutionary calculation. The choice of an operator mostly depends on the real world problem modeled, often depending on user environments and/or stereotypes. To model aggregations of different witnesses, our rules have body in disjunctive normal form. We develop fuzzy fixpoint theory and show soundness and completeness of our semantics. To control calculational efficiency, we introduce a cut with threshold. For knowledge mining and tuning of the t-operator, we restrict the problem to finding a tnorm fitting finitely many values. We show that our model of fuzzy logic programs semantically coincides with a fuzzy controller model.
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Liu, Chen, Chaoyang Dong, Qing Wang et Maopeng Ran. « Stabilization of a class of switched uncertain systems by active disturbance rejection control ». Transactions of the Institute of Measurement and Control 40, no 16 (30 mai 2018) : 4421–31. http://dx.doi.org/10.1177/0142331217749697.
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The problem of stabilization for a class of switched uncertain non-linear systems is studied by active disturbance rejection control (ADRC). Coordinate transformation is applied to transform the system into a strict feedback system in normal form. The unknown non-linearity, parameter uncertainty and external disturbance are treated as an extended state of each subsystem, and a corresponding switched extended state observer (ESO) is designed. Based on the output of the switched ESO, a switching ADRC law is proposed. Rigorous proof is given to show that the switched ESO can estimate system states and the unknown non-linearity of each subsystem effectively. Furthermore, the proposed controller guarantees the closed-loop system be semi-globally uniformly ultimately bounded for a class of switching with average dwell time. A numerical example illustrates the effectiveness of the proposed method.
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Fiaz, Muhammad, Muhammad Aqeel, Muhammad Marwan et Muhammad Sabir. « Retardational Effect and Hopf Bifurcations in a New Attitude System of Quad-Rotor Unmanned Aerial Vehicle ». International Journal of Bifurcation and Chaos 31, no 09 (juillet 2021) : 2150127. http://dx.doi.org/10.1142/s0218127421501273.
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The effect of retardation along second vector of angular velocity on a new attitude system of quad-rotor unmanned aerial vehicle (QUAV) is examined in this paper. Catastrophic and hovering conditions of rotor dynamics are verified through bifurcation analysis. It is analyzed that disturbed rotor dynamics during yaw maneuvering lead towards the existence of oscillations and hamper the efficiency of attitude system. We have categorically signified the situation where remote controller of attitude system cannot prevent flipping and consequently, shortens the life of QUAV. This type of situation arises in a strong wind friction zone where positive drag force of rotor dynamics is impeded by the magnitude of rotational moment of inertia. Moreover, subcritical and zero-Hopf bifurcations aroused due to retardational effect in attitude system are analyzed with the aid of normal form and averaging theory. Numerical simulations are also provided for validation of analytical results.
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Myers, G. A., S. Barez, W. C. Krenz et L. Stark. « Light and target distance interact to control pupil size ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 258, no 3 (1 mars 1990) : R813—R819. http://dx.doi.org/10.1152/ajpregu.1990.258.3.r813.
Texte intégralRésumé :
Light and target distance stimuli were presented to normal human subjects, and their pupillary responses were measured. A homeomorphic computer model of the pupillary control system is presented in which the form of interaction of controller signals due to light and target distance was investigated. The error remaining when model parameters were optimized to fit experimental pupil size (area or diameter) was smaller for the linear interaction hypothesis than for either power law or logical law interaction. A generalized second-order nonlinear model with six parameters (vs. 3 for each of the other models) yielded somewhat lower residual error. With the use of a modified Akaike information criterion, the value (in an information theoretic sense) of the improved fit afforded by the three additional parameters in the generalized nonlinear model was shown to be small, and thus the generalized second-order nonlinear model was rejected in favor of the simpler and more parsimonious linear model.
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Yu, Yang, Zengqiang Mi, Yiming Che, Tong Zhao et Yikun Xu. « Global Harmonic Current Rejection of Nonlinear Backstepping Control with Multivariable Adaptive Internal Model Principle for Grid-Connected Inverter under Distorted Grid Voltage ». Mathematical Problems in Engineering 2013 (2013) : 1–15. http://dx.doi.org/10.1155/2013/749798.
Texte intégralRésumé :
Based on a brief review on current harmonics generation mechanism for grid-connected inverter under distorted grid voltage, the harmonic disturbances and uncertain items are immersed into the original state-space differential equation of grid-connected inverter. A new algorithm of global current harmonic rejection based on nonlinear backstepping control with multivariable internal model principle is proposed for grid-connected inverter with exogenous disturbances and uncertainties. A type of multivariable internal model for a class of nonlinear harmonic disturbances is constructed. Based on application of backstepping control law of the nominal system, a multivariable adaptive state feedback controller combined with multivariable internal model and adaptive control law is designed to guarantee the closed-loop system globally uniformly bounded, which is proved by a constructed Lyapunov function. The presented algorithm extends rejection of nonlinear single-input systems to multivariable globally defined normal form, the correctness and effectiveness of which are verified by the simulation results.
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Kumar, Satish, Tushar Kolekar, Shruti Patil, Arunkumar Bongale, Ketan Kotecha, Atef Zaguia et Chander Prakash. « A Low-Cost Multi-Sensor Data Acquisition System for Fault Detection in Fused Deposition Modelling ». Sensors 22, no 2 (10 janvier 2022) : 517. http://dx.doi.org/10.3390/s22020517.
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Fused deposition modelling (FDM)-based 3D printing is a trending technology in the era of Industry 4.0 that manufactures products in layer-by-layer form. It shows remarkable benefits such as rapid prototyping, cost-effectiveness, flexibility, and a sustainable manufacturing approach. Along with such advantages, a few defects occur in FDM products during the printing stage. Diagnosing defects occurring during 3D printing is a challenging task. Proper data acquisition and monitoring systems need to be developed for effective fault diagnosis. In this paper, the authors proposed a low-cost multi-sensor data acquisition system (DAQ) for detecting various faults in 3D printed products. The data acquisition system was developed using an Arduino micro-controller that collects real-time multi-sensor signals using vibration, current, and sound sensors. The different types of fault conditions are referred to introduce various defects in 3D products to analyze the effect of the fault conditions on the captured sensor data. Time and frequency domain analyses were performed on captured data to create feature vectors by selecting the chi-square method, and the most significant features were selected to train the CNN model. The K-means cluster algorithm was used for data clustering purposes, and the bell curve or normal distribution curve was used to define individual sensor threshold values under normal conditions. The CNN model was used to classify the normal and fault condition data, which gave an accuracy of around 94%, by evaluating the model performance based on recall, precision, and F1 score.
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Harianingsih, Harianingsih, Suwardiyono Suwardiyono, Nugroho Eko B et Rony Wijanarko. « Perancangan Sistem Detektor Suhu Fermentasi Acetobacter Xylinum menggunakan Sensor DS18B20 ». Jurnal JTIK (Jurnal Teknologi Informasi dan Komunikasi) 2, no 1 (20 octobre 2018) : 41. http://dx.doi.org/10.35870/jtik.v2i1.44.
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a b s t r a c t Detection system temperature needed in the process of fermentation Acetobacter xylinum. Many food products produced from of fermentation this bacteria. Acetobacter xylinum need temperature fermentation between 28oC-32oCto growing good. To able for controlling temperature on fermentation Acetobacter xylinum, made a temperature design controller using Arduino Uno microcontroller and gauges the temperature of DS18B20 sensors. Election DS18B20 sensors because it had higher at 0,5 oC accuracy. The research covered structural testing component, testing functional and validation component. Data is the decimal form of signals delivered by a temperature on Arduino Uno microcontroller as the brain and processors. From test validation obtained prosesntase error for resistance (R) DS18B20 sensors for temperature 0oC-100oC of 0,96%. The testing Resistance (R) DS18B20 sensors for temperature 25oC-35oC of 1,12%. The measurement of temperature 25oC-35oC before calibration have prosentase error 9,65% and after calibration 0,70%. The prosentase error is still in a normal limits instrument temperature controller, so this instrument can be used as a control in the process of fermentation acetobacter xylinum. a b s t r a kSistem deteksi suhu sangat diperlukan dalam proses fermentasi Acetobacter xylinum. Banyak produk makanan yang diproduksi dari hasil fermentasi bakteri ini. Acetobacter xylinum memerlukan suhu fermentasi antara 28oC-32oC agar dapat tumbuh dan berkembang baik. Untuk dapat memudahkan pengontrolan suhu pada fermentasi acetobacter xylinum, dibuat rancangan alat pengendalil suhu menggunakan arduino uno sebagai mikrokontroler dan pengukur suhu berupa sensor DS18B20. Pemilihan sensor DS18B20 karena sensor ini mempunyai keakuratan tinggi yaitu 0,5oC. Rancangan penelitian meliputi pengujian struktural komponen, pengujian fungsional komponen dan uji validasi. Data merupakan bentuk desimal dari sinyal yang dikirimkan oleh sensor suhu pada mikrokontroler arduino uno sebagai otak dan pengolah data. Dari hasil uji validasi diperoleh prosentase error untuk pengujian Resistensi (R) sensor DS18B20 untuk suhu 0oC-100oC sebesar 0.96%. Hasil pengujian Resistensi (R) sensor DS18B20 untuk suhu 25oC-35oC mempunyai prosentase error 1.12%. Pengukuran suhu sensor DS18B20 untuk suhu 25oC-35oC sebelum kalibrasi mempunyai prosentase error 9.65% dan setelah kalibrasi sebesar 0.70%. Prosentase error tersebut masih dalam batas normal alat engendali suhu, sehingga alat tersebut dapat digunakan sebagai pengontrol pada proses fermentasi acetobacter xylinum..
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Huang, Yang, Jun Tang et Songyang Lao. « UAV Group Formation Collision Avoidance Method Based on Second-Order Consensus Algorithm and Improved Artificial Potential Field ». Symmetry 11, no 9 (13 septembre 2019) : 1162. http://dx.doi.org/10.3390/sym11091162.
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The problem of collision avoidance of an unmanned aerial vehicle (UAV) group is studied in this paper. A collision avoidance method of UAV group formation based on second-order consensus algorithm and improved artificial potential field is proposed. Based on the method, the UAV group can form a predetermined formation from any initial state and fly to the target position in normal flight, and can avoid collision according to the improved smooth artificial potential field method when encountering an obstacle. The UAV group adopts the “leader–follower” strategy, that is, the leader UAV is the controller and flies independently according to the mission requirements, while the follower UAV follows the leader UAV based on the second-order consensus algorithm and formations gradually form during the flight. Based on the second-order consensus algorithm, the UAV group can achieve formation maintenance easily and the Laplacian matrix used in the algorithm is symmetric for an undirected graph. In the process of obstacle avoidance, the improved artificial potential field method can solve the jitter problem that the traditional artificial potential field method causes for the UAV and avoids violent jitter. Finally, simulation experiments of two scenarios were designed to verify the collision avoidance effect and formation retention effect of static obstacles and dynamic obstacles while the two UAV groups fly in opposite symmetry in the dynamic obstacle scenario. The experimental results demonstrate the effectiveness of the proposed method.
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Goodbody, Susan J., et Daniel M. Wolpert. « Temporal and Amplitude Generalization in Motor Learning ». Journal of Neurophysiology 79, no 4 (1 avril 1998) : 1825–38. http://dx.doi.org/10.1152/jn.1998.79.4.1825.
Texte intégralRésumé :
Goodbody, Susan J. and Daniel M. Wolpert. Temporal and amplitude generalization in motor learning. J. Neurophysiol. 79: 1825–1838, 1998. A fundamental feature of human motor control is the ability to vary effortlessly over a substantial range, both the duration and amplitude of our movements. We used a three-dimensional robotic interface, which generated novel velocity dependent forces on the hand, to investigate how adaptation to these altered dynamics experienced only for movements at one temporal rate and amplitude generalizes to movements made at a different rate or amplitude. After subjects had learned to make a single point-to-point movement in a novel velocity-dependent force field, we examined the generalization of this learning to movements of both half the duration or twice the amplitude. Such movements explore a state-space not experienced during learning—any changes in behavior are due to generalization of the learning, the form of which was used to probe the intrinsic constraints on the motor control process. The generalization was assessed by determining the force field in which subjects produced kinematically normal movements. We found substantial generalization of the motor learning to the new movements supporting a nonlocal representation of the control process. Of the fields tested, the form of the generalization was best characterized by linear extrapolation in a state-space representation of the controller. Such an intrinsic constraint on the motor control process can facilitate the scaling of natural movements.
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Ko, Byung Geun, Hyok Chon Kwon et Song Jun Lee. « A Self-Sensing Method for IPMC Actuator ». Advances in Science and Technology 56 (septembre 2008) : 111–15. http://dx.doi.org/10.4028/www.scientific.net/ast.56.111.
Texte intégralRésumé :
This paper describes a novel method of self-sensing Ion-conductive Polymer Metal Composite (IPMC) actuator. Unlike the previous self-sensing technique, the proposed principle is based on the electric charge of the IPMC itself, which is correlated with its curvature. At the normal state, IPMC is electrically charged, and the amount varies according to the status of IPMC. While it is operated as an actuator, it also gives position information in the form of the electric charge amount, which is utilized for fast and accurate position control. In order to get the bending status of the actuator, the instantaneous voltage of IPMC is measured during the open state for input signal. The uncomplicated system is constructed to verify if the developed method is effective for the selfsensing actuator and evaluated by the experimental basis. The way to actuate the IPMC with selfsensing is a supplying discrete signal as an input, and it is also evaluated experimentally. This research also represents relatively simple structure for both actuation and sensing, which is very important factor to be implemented as a controller circuit for various applications.
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Tian, Tian, et Shiwu Xiao. « Electrochemical Anti-corrosion System of Iron Tower Based on Solar Power Supply ». MATEC Web of Conferences 160 (2018) : 03006. http://dx.doi.org/10.1051/matecconf/201816003006.
Texte intégralRésumé :
Aiming at the serious problem of the corrosion of the transmission tower in the coastal area or in the harsh industrial area, a kind of electro-chemical anti-corrosion system based on solar power is designed. The system consists of a solar power module and an electrochemical anti-corrosion module: The solar power module consists of a solar panel, a photovoltaic controller, a accumulator and a constant potentiometer. The Electrochemical anti-corrosion modules include an anode block and an anode bed and reference electrode. The photovoltaic energy technology and forced current cathodic protection technology are used in the system, to achieve the effective protection of the tower anti-corrosion. Solar power supply to the nearest, solve the long-distance transmission loss and the high installation costs, form a simple structure, stable operation, low cost, clean and environmental protection, long service life of anti-corrosion system, with good economic efficiency and social benefits. It is of great significance to ensure the safe operation of the tower, maintain the normal operation of the power grid, and even promotes the optimization and upgrading of the industrial structure, save energy and reduces emissions, improve the safe and stable operation of the power system and the economic benefits, etc.
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Kong, Xiangsong, Changqing Shi, Hang Liu, Pengcheng Geng, Jiabin Liu et Yasen Fan. « Performance Optimization of a Steam Generator Level Control System via a Revised Simplex Search-Based Data-Driven Optimization Methodology ». Processes 10, no 2 (28 janvier 2022) : 264. http://dx.doi.org/10.3390/pr10020264.
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A Steam generator is a crucial device of a nuclear power plant. Control performance of the steam generator level control system is key to its normal operation. To improve its performance, the control system parameters should be optimized by utilizing a proper optimization method. Furthermore, the method’s efficiency is critical for its operability in the actual plant. However, the steam generator level process is a complex process, with high nonlinearity and time-varying properties. Traditional parameters tuning methods are experience-based, cumbersome, and time-consuming. To address the challenge, a systemic data-driven optimization methodology based on the model-free optimization with a revised simplex search method was proposed. Rather than the traditional controller parameter tuning method, this method optimizes the control system directly by using control performance measurements. To strengthen its efficiency, two critical modifications were incorporated into the traditional simplex search method to form a knowledge-informed simplex search based on historical gradient approximations. Firstly, with the help of the historical gradient approximations, the revised method could sense the optimization direction more accurately and accomplish the iteration step size tuning adaptively, significantly reducing the optimization cost. Secondly, a revised iteration termination control strategy was developed and integrated to monitor the optimization progress, which can promptly terminate the progress to avoid unnecessary iteration costs. The effectiveness and the efficiency of the revised method were demonstrated through simulation experiments.
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Liu, S., A. R. Messina et V. Vittal. « Assessing Placement of Controllers and Nonlinear Behavior Using Normal Form Analysis ». IEEE Transactions on Power Systems 20, no 3 (août 2005) : 1486–95. http://dx.doi.org/10.1109/tpwrs.2005.852052.
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Tweed, D., H. Misslisch et M. Fetter. « Testing models of the oculomotor velocity-to-position transformation ». Journal of Neurophysiology 72, no 3 (1 septembre 1994) : 1425–29. http://dx.doi.org/10.1152/jn.1994.72.3.1425.
Texte intégralRésumé :
1. Do neural computations in premotor circuits mirror the physical properties of the systems they control? In 1987, Tweed and Vilis showed that oculomotor theories where a neural integrator converts eye angular velocity commands into position commands cannot be correct, because angular position is not the integral of angular velocity. Recently Schnabolk and Raphan proposed that an angular velocity integrator is nevertheless used to generate tonic commands in the oculomotor system. Here we test the Schnabolk-Raphan (S-R) model against Tweed and Vilis's quaternion (Q) model of the velocity to position transformation. 2. The S-R model predicts large (up to 7 degrees) transient (approximately 700 ms) deviations ("blips") in torsional eye position during attempted horizontal and vertical saccades. The Q model predicts no blips. Search coil recordings of saccades by 7 normal human subjects showed no large blips. 3. For approximately 200 saccades by each subject, we plotted the area under the torsional blip versus the product of saccade eccentricity and magnitude. According to the S-R model, this graph should form a straight line with slope 1.00. According to the Q model, the slope should be zero. Measured slopes averaged 0.016 (range -0.073 to 0.061) for saccade targets at 20 degrees eccentricity and 0.040 (range 0.004-0.076) for targets at 40 degrees. 4. No parameter change can significantly improve the S-R model, but lowering one parameter eradicates the tiny inaccuracy in the Q model. We show that the fundamental reason for the S-R model's failure is its use of a commutative controller to steer a noncommutative plant.
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Zou, Z. Y., Q. Y. Jiang, Y. J. Cao et H. F. Wang. « Normal form analysis of interactions among multiple SVC controllers in power systems ». IEE Proceedings - Generation, Transmission and Distribution 152, no 4 (2005) : 469. http://dx.doi.org/10.1049/ip-gtd:20049009.
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Guo, Peng, Ronghua Wang, Zhebin Shen, Haorong Zhang, Peng Zhang, Fei Lou, Hengbo Li et Yijie Wu. « A Feedrate-Constraint Method for Continuous Small Line Segments in CNC Machining Based on Nominal Acceleration ». Applied Sciences 11, no 19 (23 septembre 2021) : 8837. http://dx.doi.org/10.3390/app11198837.
Texte intégralRésumé :
When the CNC machining of continuous small line segments is performed, the direction of the machine tool movement will change abruptly at the corner of adjacent line segments. Therefore, a reasonable constraint on the feedrate at the corner is the prerequisite for achieving high-speed and high-precision machining. To achieve this goal, a feedrate-constraint method based on the nominal acceleration was proposed. The proposed method obtains the predicted value of acceleration during the machining process by the machining trajectory prediction and acceleration filtering. Then, the feedrate at the corner is constrained, according to the predicted acceleration. Specifically, for any corner of adjacent line segments, the proposed method assumes that the CNC machining of a short path centered on the corner is carried out at a constant feedrate. First, the actual machining trajectory is predicted according to the transfer function of the servo system. Then, the nominal acceleration, when the CNC machining is carried out to the corner, is calculated and processed by a low-pass FIR filter. Last, the feedrate-constraint value at the corner is obtained according to the nominal acceleration and the preset normal acceleration. The advantage of the proposed method is that it can be used for different machining paths consisting of long segments or continuous small segments and it has no special requirement for the accuracy of the machining path. As a result, the feedrate-constraint value obtained is reasonable and the smooth machining process can be ensured. The simulation results in both 2D and 3D machining paths show that the proposed method is insensitive to the length of the line segment and the angle of the corner, and the calculated feedrate-constraint value is close to the theoretical value, which has good stability and versatility. In contrast, the feedrate-constraint values obtained by conventional methods change abruptly along the machining path, especially in the 3D simulation, which will damage the machining quality. The experiment was performed on a three-axis CNC machine tool controlled by a self-developed controller, and a free-form surface workpiece was machined by a conventional feedrate-constraint method and the proposed method, respectively. The experimental results showed that the proposed method can make the feedrate of the machining process higher and more stable. Then, machining defects such as overcutting and undercutting can be avoided and the machining quality can be improved. Therefore, the article proposes a new method to constrain the feedrate at the corner of continuous small line segments, which can improve the machining efficiency and quality of the CNC machining.
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Li, Xiang, et Ranchao Wu. « Dynamics of a New Hyperchaotic System with Only One Equilibrium Point ». Journal of Mathematics 2013 (2013) : 1–9. http://dx.doi.org/10.1155/2013/935384.
Texte intégralRésumé :
A new 4D hyperchaotic system is constructed based on the Lorenz system. The compound structure and forming mechanism of the new hyperchaotic attractor are studied via a controlled system with constant controllers. Furthermore, it is found that the Hopf bifurcation occurs in this hyperchaotic system when the bifurcation parameter exceeds a critical value. The direction of the Hopf bifurcation as well as the stability of bifurcating periodic solutions is presented in detail by virtue of the normal form theory. Numerical simulations are given to illustrate and verify the results.
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Chen, Yong-Tong, Mingyu Liu et Zhong-Chen Cao. « Effect of Robot Motion Accuracy on Surface Form during Computer-Controlled Optical Surfacing Process ». Applied Sciences 12, no 23 (1 décembre 2022) : 12301. http://dx.doi.org/10.3390/app122312301.
Texte intégralRésumé :
Nowadays, large-aperture optical components are increasingly used in high-power laser systems, remote-sensing satellites, and space-based astronomical telescopes. Fabricating these surfaces with submicron-scale shape accuracy and a nanoscale surface finish has been a great challenge for the optical industry, especially for hard and difficult-to-machine materials. Thus, to achieve the high-efficiency and high-precision polishing of large-aperture aspherical optical parts, this study combined robotic machining technology with computer-controlled optical surfacing (CCOS) technology and investigated the effect of robot motion accuracy on the surface topography of workpieces during polishing. First, a material removal model considering the normal error of the polishing tool was developed based on contact mechanics, kinematic theory, and the abrasion mechanism. Next, in combination with the polishing trajectory, the surface morphology and form accuracy after polishing were predicted under different normal-error conditions. Then, preliminary experiments were conducted to verify the model. The experimental data agreed with the simulation results, showing that as the normal error increased from 0° to 0.5° and 1°, the peak-to-valley (PV) values of the surface profile of the optical element decreased from 5.42, 5.28, and 4.68 μm to 3.97, 4.09, and 4.43 μm, respectively. The corresponding convergence rates were 26.8%, 22.5%, and 5.3%. The root mean square (RMS) values decreased from 0.754, 0.895, and 0.678 μm to 0.593, 0.620, and 0.583 μm, with corresponding convergence rates of 21.4%, 30.7% and 14.0%, respectively. Moreover, a higher motion accuracy enabled the polishing robot to reduce the mid- and high-frequency errors of the optical element.
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PAGANO, DANIEL, LUIS PIZARRO et JAVIER ARACIL. « LOCAL BIFURCATION ANALYSIS IN THE FURUTA PENDULUM VIA NORMAL FORMS ». International Journal of Bifurcation and Chaos 10, no 05 (mai 2000) : 981–95. http://dx.doi.org/10.1142/s0218127400000700.
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Inverted pendulums are very suitable to illustrate many ideas in automatic control of nonlinear systems. The rotational inverted pendulum is a novel design that has some interesting dynamics features that are not present in inverted pendulums with linear motion of the pivot. In this paper the dynamics of a rotational inverted pendulum has been studied applying well-known results of bifurcation theory. Two classes of local bifurcations are analyzed by means of the center manifold theorem and the normal form theory — first, a pitchfork bifurcation that appears for the open-loop controlled system; second, a Hopf bifurcation, and its possible degeneracies, of the equilibrium point at the upright pendulum position, that is present for the controlled closed-loop system. Some numerical results are also presented in order to verify the validity of our analysis.
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Liu, Yongjian, Xiezhen Huang et Jincun Zheng. « Chaos and bifurcation in the controlled chaotic system ». Open Mathematics 16, no 1 (3 novembre 2018) : 1255–65. http://dx.doi.org/10.1515/math-2018-0105.
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AbstractIn this paper, chaos and bifurcation are explored for the controlled chaotic system, which is put forward based on the hybrid strategy in an unusual chaotic system. Behavior of the controlled system with variable parameter is researched in detain. Moreover, the normal form theory is used to analyze the direction and stability of bifurcating periodic solution.
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Su, Xiao Ling, et Jian Ming Zhan. « Study on the Fuzzy-PID Policy for Force Control in Free-Form Surfaces Polishing by Robots ». Applied Mechanics and Materials 101-102 (septembre 2011) : 422–26. http://dx.doi.org/10.4028/www.scientific.net/amm.101-102.422.
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When a robot is used to polish or finish a curved surface, both feed movement and contact force have to be controlled at the same time so that the polishing tool would machine its work-piece at the right position in right posture with required force. In this paper, a passive wrist system is developed to adapt the shape of the machining curved surface by changing its posture along with the surface. And under the Fuzzy-PID policy, polishing force is controlled at a stable value in the normal direction of the named machining point while the polishing tool moving along the curved surface by multi-point machining. It means that the passive wrist system and the model of the surroundings could be used in force controlling when robots polish free-form surfaces with multi-point machining by a grinding ring.
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Tobin, John, William Delaney et Harry Doyle. « The controlled drinking controversy ». Irish Journal of Psychological Medicine 10, no 2 (juin 1993) : 121–23. http://dx.doi.org/10.1017/s0790966700013033.
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AbstractObjective:of the review was to explore the three major controversies over the controlled drinking debate, and to assess for whom controlled drinking may be a viable form of treatment of alcohol dependence.Method:was to survey the literature of the last twenty years, using the Medline data base, the Index Medicus, and the Excerpta Medica.Findings:were that controversies involving the work of the Sobells and the Rand reports were influenced by the social attitudes of the time, and that D.L. Davies work despite being methodologically unsound, made the consideration of having a controlled drinking goal a viable treatment option. We also found that comparing studies using different definitions of controlled/normal drinking is difficult, but it would appear that the young, married, less severely dependent, and possibly female drinker may benefit from this form of treatment. The return of a patient to controlled drinking is not always dependent on the treatment model they have undergone.Conclusions:are that controlled drinking should be considered as a serious option, and that the recommended safe alcohol intake, will differ between patients, and that flexibility will be required. Also that a source of ongoing collateral information about the patient is essential.
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Li, Jing, Ziyu Guo, Yinzhu Quan et Jian Li. « Nonlinear dynamic analysis and hypernormal form of truss core sandwich plates ». Journal of Applied Biomaterials & ; Functional Materials 16, no 1_suppl (janvier 2018) : 37–45. http://dx.doi.org/10.1177/2280800018757336.
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Introduction: Truss core material, which is a new type of ultra-light material with comprehensive properties, is used in the aerospace industry. The aim of this paper is to investigate the dynamic behavior of three-dimensional Kagome sandwich plates with truss core under transverse and in-plane excitation in the case of 1:1 internal resonance. Methods: Firstly, the averaged equation is obtained by means of the method of multiple scales. Then, the nonlinear system is analyzed applying the theory of normal form. Eventually, we analyze the dynamic behavior, mainly periodic motions, for the truss core sandwich panels by using numerical simulation. Results: Numerical results are presented here for the nonlinear dynamic behavior of the model of truss core sandwich plates, which provides theoretical guidance to vibration control. Conclusions: Considerable insight has been gained concerning the sign of parameter of the model controlled by material property.
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Ni, Qi, et Nathan Crane. « Controlling Normal Stiffness in Droplet-Based Linear Bearings ». Micromachines 9, no 10 (17 octobre 2018) : 525. http://dx.doi.org/10.3390/mi9100525.
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While capillary forces are negligible relative to gravity at the macroscale, they provide adequate force to effectively manipulate millimeter to micro meter objects. The fluidic actuation can be accomplished using droplets that also act as bearings. While rotary droplet bearings have been previously demonstrated, this paper addresses the positioning accuracy of a droplet-based bearing consisting of a droplet between a moving plate and a stationary substrate with constrained wetting region under a normal load. Key wetting cases are analyzed using both closed form analytical approximations and numerical simulations. The vertical force and stiffness characteristics are analyzed in relation to the wetting boundaries of the supporting surface. Case studies of different wetting boundaries are presented and summarized. Design strategies are presented for maximizing load carrying capability and stiffness. These results show that controlled wetting and opposing droplet configurations can create much higher stiffness fluidic bearings than simple droplets.
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Polishchuk, D. M., M. Persson, M. M. Kulyk, G. Baglioni, B. A. Ivanov et V. Korenivski. « Oscillatory exchange bias controlled by RKKY in magnetic multilayers ». Applied Physics Letters 122, no 6 (6 février 2023) : 062405. http://dx.doi.org/10.1063/5.0133125.
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Ferromagnetic/antiferromagnetic bilayers are interfaced with normal metal/ferromagnetic bilayers to form F*/AF/N/F valves. The N-spacer thickness is chosen such that it mediates strong indirect exchange [Ruderman–Kittel–Kasuya–Yosida (RKKY)] between the outer ferromagnetic layers, which varies in strength/direction depending on the N thickness and changes its direction on switching F. The system exhibits a strong modulation of the F*/AF exchange bias, oscillating in strength synchronously with the oscillation in the interlayer RKKY exchange across the normal metal spacer. The effect is explained as due to a superposition taking place within the antiferromagnetic layer of the direct-exchange proximity effect from the F*/AF interface and the indirect RKKY exchange from F penetrating AF via N. The modulation, expressed via the strength of the F*/AF bias field, reaches 400% at the first RKKY peak.