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Journal articles on the topic 'Continuous-Discrete observers'

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Author: Grafiati

Published: 7 July 2024

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1

Dorfler, Florian, Fabio Pasqualetti, and Francesco Bullo. "Continuous-Time Distributed Observers With Discrete Communication." IEEE Journal of Selected Topics in Signal Processing 7, no. 2 (April 2013): 296–304. http://dx.doi.org/10.1109/jstsp.2013.2245300.

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2

Ahmed-Ali, Tarek, Romain Postoyan, and Françoise Lamnabhi-Lagarrigue. "Continuous–discrete adaptive observers for state affine systems." Automatica 45, no. 12 (December 2009): 2986–90. http://dx.doi.org/10.1016/j.automatica.2009.09.005.

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3

Goffaux, G., A. Vande Wouwer, and O. Bernard. "Continuous - discrete interval observers for monitoring microalgae cultures." Biotechnology Progress 25, no. 3 (May 2009): 667–75. http://dx.doi.org/10.1002/btpr.167.

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4

Byrski, Jędrzej, and Witold Byrski. "State estimators and observers for continuous and discrete linear systems. Part 1. Differential asymptotic state estimators." Science, Technology and Innovation 3, no. 2 (December 27, 2018): 62–68. http://dx.doi.org/10.5604/01.3001.0012.8169.

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In the paper an overview of state estimators and state observers used in linear systems, will be presented. The state estimators and observers can be used in many applications like the state reconstruction for the control purposes or for the diagnosis and fault detection in technical processes or for the virtual measurements of inaccessible variables of the system as well as for the best filtration of the differential equation solution. As the standard most commonly the Kalman filter and Luenberger type observers are used. Although the Kalman filter guarantees optimal filtering quality of the state, reconstructed from the noisy measurements, both Kalman filter and the Luenberger observer guarantee only asymptotic quality of the real state changes and tracking, basing on the current measurements of the system output and input signals. Unfortunately, the value of the estimation error at any moment of time cannot be calculated. The discussion on differences between continuous and two types of discrete Kalman Filter will be presented. This paper is plan to be the introduction to presentation of the another type of the state observers which have the structure given by the integral operators. Based on measurements of the system output and input signals on some predefined finite time interval, they can reconstruct, after this interval, the observed state exactly.

5

Byrski, Jędrzej, and Witold Byrski. "State estimators and observers for continuous and discrete linear systems. Part 2. Integral observers for exact state reconstruction." Science, Technology and Innovation 5, no. 2 (June 30, 2019): 23–33. http://dx.doi.org/10.5604/01.3001.0013.2871.

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In the paper, the exact state observers will be presented. The state estimators and observers can be used in technical processes for many purposes like the fault detection and diagnosis, the implementation of the state controllers, and soft reconstruction of inaccessible for measurements variables of the system. As the standard, for continuous systems the differential estimators of Kalman filter or Luenberger type observer are commonly used. However, if the initial conditions of the real state are unknown, both estimators guarantee only an asymptotic quality of the real state tracking. The paper presents another type of the state observers, which for continuous system have the structure given by two integral operators. Based on measurements of the system input and output signals on some predefined finite time interval T, they can reconstruct the initial state exactly. In on-line version, the exact state reconstruction is performed continuously for every t, based on special procedure executed within two moving windows of width T, on sliding time interval [t-T, t].

6

Harrigan, Jinni A., John R. Kues, and Joseph G. Weber. "Impressions of Hand Movements: Self-Touching and Gestures." Perceptual and Motor Skills 63, no. 2 (October 1986): 503–16. http://dx.doi.org/10.2466/pms.1986.63.2.503.

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Two studies addressed the question of observers' impressions of physicians and patients who displayed self-touching, a behavior reported to indicate negative affect. In Study 1 self-touching was regarded as more Expressive and Warm, while control scenes were viewed as more Calm. The results of Study 2 showed that observers judged hand gestures most positively, followed by self-touching, and control scenes on Expressive, Sincere, Natural, and Warm. Control scenes were seen as most Calm. These findings confirm earlier results and represent a perspective on self-touching that has not been previously examined, the observer's viewpoint. It is the observer who tends to be most influenced by the display of self-touching. Discussion is focused on discrete and continuous self-touching, the effect of type and context of self-touching, and the need for considering other functions (i.e., serving information-processing demands) of self-touching than indicating states of anxiety, tension, or hostility.

7

Astorga, C. M., N. Othman, S. Othman, H. Hammouri, and T. F. McKenna. "Nonlinear continuous–discrete observers: application to emulsion polymerization reactors." Control Engineering Practice 10, no. 1 (January 2002): 3–13. http://dx.doi.org/10.1016/s0967-0661(01)00100-9.

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8

Shouse, K. R., and D. G. Taylor. "Discrete-time observers for singularly perturbed continuous-time systems." IEEE Transactions on Automatic Control 40, no. 2 (1995): 224–35. http://dx.doi.org/10.1109/9.341780.

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9

Mazenc, Frédéric, Vincent Andrieu, and Michael Malisoff. "Design of continuous–discrete observers for time-varying nonlinear systems." Automatica 57 (July 2015): 135–44. http://dx.doi.org/10.1016/j.automatica.2015.04.016.

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10

Mazenc, Frédéric, and Emilia Fridman. "Predictor-based sampled-data exponential stabilization through continuous–discrete observers." Automatica 63 (January 2016): 74–81. http://dx.doi.org/10.1016/j.automatica.2015.10.016.

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11

Eisma, Yke Bauke, Anouk E. Looijestijn, and Joost C. F. de Winter. "Attention Distribution While Detecting Conflicts between Converging Objects: An Eye-Tracking Study." Vision 4, no. 3 (July 22, 2020): 34. http://dx.doi.org/10.3390/vision4030034.

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In many domains, including air traffic control, observers have to detect conflicts between moving objects. However, it is unclear what the effect of conflict angle is on observers’ conflict detection performance. In addition, it has been speculated that observers use specific viewing techniques while performing a conflict detection task, but evidence for this is lacking. In this study, participants (N = 35) observed two converging objects while their eyes were recorded. They were tasked to continuously indicate whether a conflict between the two objects was present. Independent variables were conflict angle (30, 100, 150 deg), update rate (discrete, continuous), and conflict occurrence. Results showed that 30 deg conflict angles yielded the best performance, and 100 deg conflict angles the worst. For 30 deg conflict angles, participants applied smooth pursuit while attending to the objects. In comparison, for 100 and especially 150 deg conflict angles, participants showed a high fixation rate and glances towards the conflict point. Finally, the continuous update rate was found to yield shorter fixation durations and better performance than the discrete update rate. In conclusion, shallow conflict angles yield the best performance, an effect that can be explained using basic perceptual heuristics, such as the ‘closer is first’ strategy. Displays should provide continuous rather than discrete update rates.

12

Farza, M., M. M'Saad, M. L. Fall, E. Pigeon, O. Gehan, and K. Busawon. "Continuous-Discrete Time Observers for a Class of MIMO Nonlinear Systems." IEEE Transactions on Automatic Control 59, no. 4 (April 2014): 1060–65. http://dx.doi.org/10.1109/tac.2013.2283754.

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13

Goffaux, G., A. Vande Wouwer, and O. Bernard. "Improving continuous–discrete interval observers with application to microalgae-based bioprocesses." Journal of Process Control 19, no. 7 (July 2009): 1182–90. http://dx.doi.org/10.1016/j.jprocont.2009.03.009.

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14

Mazenc, Frédéric, and Thach Ngoc Dinh. "Construction of interval observers for continuous-time systems with discrete measurements." Automatica 50, no. 10 (October 2014): 2555–60. http://dx.doi.org/10.1016/j.automatica.2014.08.008.

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15

Zhao, Guanglei, and Changchun Hua. "Continuous–discrete-time adaptive observers for nonlinear systems with sampled output measurements." International Journal of Systems Science 48, no. 12 (May 12, 2017): 2599–609. http://dx.doi.org/10.1080/00207721.2017.1324924.

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16

Boizot, Nicolas, and Eric Busvelle. "On the stability of a differential Riccati equation for continuous-discrete observers." International Journal of Control 89, no. 2 (August 28, 2015): 322–36. http://dx.doi.org/10.1080/00207179.2015.1076937.

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17

Ménard, Tomas, Emmanuel Bernuau, Emmanuel Moulay, and Patrick Coirault. "Continuous–discrete time observers for homogeneous nonlinear systems with sampled-data outputs." Automatica 151 (May 2023): 110905. http://dx.doi.org/10.1016/j.automatica.2023.110905.

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18

Escobar-Jiménez, R. F., M. Alegría-Zamudio, A. C. Téllez-Anguiano, and V. H. Olivares-Peregrino. "Sensor FDI System Based on Discrete-TimeFractional-Order Observers." Mathematical Problems in Engineering 2023 (February 17, 2023): 1–10. http://dx.doi.org/10.1155/2023/9984828.

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The design of sensor fault detection and isolation (FDI) systems has been studied widely by several authors of different fields of science (engineering, mathematics, physics) to ensure the continuous operation of systems or processes. This research presents the design and evaluation of a fault detection and isolation (FDI) system based on discrete fractional-orderhigh-gain observers (DFOHGO) for the outlet temperature sensors of a heat exchanger. The formulation of the discrete fractional-order observers is based on the Grünwald–Letnikov fractional-order derivative. The FDI system is based on a bank of two DFOHGOs to carry out a residual evaluation. The obtained results showed that the DFOHGOs provide accurate estimations of the temperatures. This allows switching the faulty sensor signal to the temperature estimations provided by the DFOHGOs when a fault occurs.

19

ENGEL, B., G. BRUIN, G. ANDRE, and W. BUIST. "Assessment of observer performance in a subjective scoring system: visual classification of the gait of cows." Journal of Agricultural Science 140, no. 3 (May 2003): 317–33. http://dx.doi.org/10.1017/s0021859603002983.

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As with any measurement procedure, the performance of a subjective classification procedure must be evaluated. Observers have to be trained and their performance has to be assessed, preferably on a regular basis, to guarantee sufficient consistency and accuracy of classification results. The current paper is a study of observer performance where observers were asked to classify the gait of cows from video recordings. Gait was classified in nine ordered categories (ranging from 1=normal gait to 9=severely abnormal gait) and also as a continuous fraction by putting a mark on a paper strip (the left end corresponding to 0=normal gait and the right end to 1=severely abnormal gait). The use of statistical models and methodology for analysis of these visual scores is demonstrated and discussed. Observers were assessed by comparing their classification results with the results of an expert. Models and methodology take proper account of typical features of the data, i.e. the fact that data are discrete scores or continuous scores with an upper and lower bound, the variance heterogeneity and non-linearity of model terms that arises from this, and the dependence between repeated classifications of videos of the same cow. Results of the analyses are summarized in simple tables and plots. These are useful tools to indicate possible flaws in judgement of an observer, that may be corrected by further training. When a high standard is developed, which usually takes the form of the opinion of one or more experts, this methodology can be applied prior to any experiment where responses are ordered subjective scores.

20

Pengov, Marco, Edouard Richard, and Jean-Claude Vivalda. "Continuous-Discrete Observers for Global Stabilization of Nonlinear Systems with Applications to Bioreactors." European Journal of Control 8, no. 5 (January 2002): 465–76. http://dx.doi.org/10.3166/ejc.8.465-476.

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21

Mazenc, Frederic, and Michael Malisoff. "Continuous Discrete Sequential Observers for Time-Varying Systems Under Sampling and Input Delays." IEEE Transactions on Automatic Control 65, no. 4 (April 2020): 1704–9. http://dx.doi.org/10.1109/tac.2019.2930676.

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22

Astorga-Zaragoza, Carlos-Manuel, Sami Othman, and Hassan Hammouri. "ON-LINE MONITORING AND CONTROL OF NON-LINEAR SYSTEMS VIA CONTINUOUS-DISCRETE OBSERVERS." IFAC Proceedings Volumes 35, no. 1 (2002): 455–60. http://dx.doi.org/10.3182/20020721-6-es-1901.00487.

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23

Caliskan, Fikret, and Mohamed A. Zohdy. "Robust quadratic stabilization applied to design of continuous-time and discrete-time observers." ISA Transactions 42, no. 3 (July 2003): 381–89. http://dx.doi.org/10.1016/s0019-0578(07)60141-4.

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24

Darouach, Mohamed, Francesco Amato, and Marouane Alma. "Functional observers design for descriptor systems via LMI: Continuous and discrete-time cases." Automatica 86 (December 2017): 216–19. http://dx.doi.org/10.1016/j.automatica.2017.08.016.

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25

Chen, Jeng-Tzong, Jia-Wei Lee, Yi-Ling Huang, Cheng-Hsiang Shao, and Cheng-Hsuan Lu. "On the linkage between influence matrices in the BIEM and BEM to explain the mechanism of degenerate scale for a circular domain." Journal of Mechanics 37 (2021): 339–45. http://dx.doi.org/10.1093/jom/ufab003.

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ABSTRACT In this paper, we proposed two ways to understand the rank deficiency in the continuous system (boundary integral equation method, BIEM) and discrete system (boundary element method, BEM) for a circular case. The infinite-dimensional degree of freedom for the continuous system can be reduced to finite-dimensional space using the generalized Fourier coordinates. The property of the second-order tensor for the influence matrix under different observers is also examined. On the other hand, the discrete system in the BEM can be analytically studied, thanks to the spectral property of circulant matrix. We adopt the circulant matrix of odd dimension, (2N + 1) by (2N + 1), instead of the previous even one of 2N by 2N to connect the continuous system by using the Fourier bases. Finally, the linkage of influence matrix in the continuous system (BIE) and discrete system (BEM) is constructed. The equivalence of the influence matrix derived by using the generalized coordinates and the circulant matrix are proved by using the eigen systems (eigenvalue and eigenvector). The mechanism of degenerate scale for a circular domain can be analytically explained in the discrete system.

26

Zhang, Tingting, Frédéric Kratz, Yunhui Hou, and Vincent Idasiak. "A Continuous-Discrete Finite Memory Observer Design for a Class of Nonlinear Systems: Application to Fault Diagnosis." Mathematical Problems in Engineering 2020 (July 16, 2020): 1–14. http://dx.doi.org/10.1155/2020/7312521.

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This paper aims to develop a continuous-discrete finite memory observer (CD-FMO) for a class of nonlinear dynamical systems modeled by ordinary differential equations (ODEs) with discrete measurements. The nonlinear systems under consideration are at least locally Lipschitz, which guarantees the existence and uniqueness of solution at each time instant. The proposed nonlinear observer uses a finite number of collected measurements to estimate the system state in the presence of measurement noise. Besides, a one-step prediction algorithm incorporated with an iterative-update scheme is performed to solve the integral problem caused by system nonlinearity, and an analysis of the numerical integration approximation error is given. The properties of estimation performance have been further proved in deterministic case and been analyzed by Monte Carlo simulation in stochastic cases. It is worth noting that the presented method has a finite-time convergence, while most nonlinear observers are usually asymptotically convergent. Another advantage of CD-FMO is that it has no initial value problem. For the application purpose, residuals are generated to implement fault detection cooperated with Cumulative Sum (CUSUM) control charts, while a bank of CD-FMOs is adopted to realize fault isolation for different sensor and actuator faults of the considered nonlinear robotic arm. The robustness and effectiveness of the proposed approach are illustrated via the simulation results.

27

Khlebnikov, Mikhail. "Sparse Filtering Under Norm-Bounded Exogenous Disturbances Using Observers." SYSTEM THEORY, CONTROL AND COMPUTING JOURNAL 2, no. 1 (June 30, 2022): 1–7. http://dx.doi.org/10.52846/stccj.2022.2.1.29.

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The paper considers the sparse filtering problem under arbitrary norm-bounded exogenous disturbances. We propose a simple and universal observer-based approach to its solution, based on the LMI technique and the method of invariant ellipsoids; it allows the use of a reduced number of system outputs. From a technical point of view of application, we reduce the original problem to semi-definite programming, which is easily solved numerically. The proposed simple approach is easy to implement and can be equally extended to systems in continuous and discrete time.

28

Davila, Jorge, Alessandro Pisano, and Elio Usai. "Continuous and discrete state reconstruction for nonlinear switched systems via high-order sliding-mode observers." International Journal of Systems Science 42, no. 5 (May 2011): 725–35. http://dx.doi.org/10.1080/00207721.2010.518254.

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29

Radisavljevic-Gajic, Verica, Dimitri Karagiannis, and Zoran Gajic. "Linear, Nonlinear, and Distributed-Parameter Observers Used for (Renewable) Energy Processes and Systems—An Overview." Energies 17, no. 11 (June 2, 2024): 2700. http://dx.doi.org/10.3390/en17112700.

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Full- and reduced-order observers have been used in many engineering applications, particularly for energy systems. Applications of observers to energy systems are twofold: (1) the use of observed variables of dynamic systems for the purpose of feedback control and (2) the use of observers in their own right to observe (estimate) state variables of particular energy processes and systems. In addition to the classical Luenberger-type observers, we will review some papers on functional, fractional, and disturbance observers, as well as sliding-mode observers used for energy systems. Observers have been applied to energy systems in both continuous and discrete time domains and in both deterministic and stochastic problem formulations to observe (estimate) state variables over either finite or infinite time (steady-state) intervals. This overview paper will provide a detailed overview of observers used for linear and linearized mathematical models of energy systems and review the most important and most recent papers on the use of observers for nonlinear lumped (concentrated)-parameter systems. The emphasis will be on applications of observers to renewable energy systems, such as fuel cells, batteries, solar cells, and wind turbines. In addition, we will present recent research results on the use of observers for distributed-parameter systems and comment on their actual and potential applications in energy processes and systems. Due to the large number of papers that have been published on this topic, we will concentrate our attention mostly on papers published in high-quality journals in recent years, mostly in the past decade.

30

Briat, Corentin, and Mustafa Khammash. "Interval peak-to-peak observers for continuous- and discrete-time systems with persistent inputs and delays." Automatica 74 (December 2016): 206–13. http://dx.doi.org/10.1016/j.automatica.2016.07.043.

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31

Floquet, T., D. Mincarelli, A. Pisano, and E. Usai. "Continuous and Discrete State Estimation in Linear Switched Systems by Sliding Mode Observers with Residuals' Projection." IFAC Proceedings Volumes 45, no. 9 (2012): 265–70. http://dx.doi.org/10.3182/20120606-3-nl-3011.00092.

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32

Voortman, Quentin, Alexander Pogromsky, Alexey Matveev, and Henk Nijmeijer. "Data-Rate Constrained Observers of Nonlinear Systems." Entropy 21, no. 3 (March 14, 2019): 282. http://dx.doi.org/10.3390/e21030282.

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In this paper, the design of a data-rate constrained observer for a dynamical system is presented. This observer is designed to function both in discrete time and continuous time. The system is connected to a remote location via a communication channel which can transmit limited amounts of data per unit of time. The objective of the observer is to provide estimates of the state at the remote location through messages that are sent via the channel. The observer is designed such that it is robust toward losses in the communication channel. Upper bounds on the required communication rate to implement the observer are provided in terms of the upper box dimension of the state space and an upper bound on the largest singular value of the system’s Jacobian. Results that provide an analytical bound on the required minimum communication rate are then presented. These bounds are obtained by using the Lyapunov dimension of the dynamical system rather than the upper box dimension in the rate. The observer is tested through simulations for the Lozi map and the Lorenz system. For the Lozi map, the Lyapunov dimension is computed. For both systems, the theoretical bounds on the communication rate are compared to the simulated rates.

33

Erb, Wendy M., Whitney Ross, Haley Kazanecki, Tatang Mitra Setia, Shyam Madhusudhana, and Dena J. Clink. "Vocal complexity in the long calls of Bornean orangutans." PeerJ 12 (May 14, 2024): e17320. http://dx.doi.org/10.7717/peerj.17320.

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Vocal complexity is central to many evolutionary hypotheses about animal communication. Yet, quantifying and comparing complexity remains a challenge, particularly when vocal types are highly graded. Male Bornean orangutans (Pongo pygmaeus wurmbii) produce complex and variable “long call” vocalizations comprising multiple sound types that vary within and among individuals. Previous studies described six distinct call (or pulse) types within these complex vocalizations, but none quantified their discreteness or the ability of human observers to reliably classify them. We studied the long calls of 13 individuals to: (1) evaluate and quantify the reliability of audio-visual classification by three well-trained observers, (2) distinguish among call types using supervised classification and unsupervised clustering, and (3) compare the performance of different feature sets. Using 46 acoustic features, we used machine learning (i.e., support vector machines, affinity propagation, and fuzzy c-means) to identify call types and assess their discreteness. We additionally used Uniform Manifold Approximation and Projection (UMAP) to visualize the separation of pulses using both extracted features and spectrogram representations. Supervised approaches showed low inter-observer reliability and poor classification accuracy, indicating that pulse types were not discrete. We propose an updated pulse classification approach that is highly reproducible across observers and exhibits strong classification accuracy using support vector machines. Although the low number of call types suggests long calls are fairly simple, the continuous gradation of sounds seems to greatly boost the complexity of this system. This work responds to calls for more quantitative research to define call types and quantify gradedness in animal vocal systems and highlights the need for a more comprehensive framework for studying vocal complexity vis-à-vis graded repertoires.

34

Lewis, Alan, and Tim Miller. "Deceptive Reinforcement Learning in Model-Free Domains." Proceedings of the International Conference on Automated Planning and Scheduling 33, no. 1 (July 1, 2023): 587–95. http://dx.doi.org/10.1609/icaps.v33i1.27240.

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This paper investigates deceptive reinforcement learning for privacy preservation in model-free and continuous action space domains. In reinforcement learning, the reward function defines the agent's objective. In adversarial scenarios, an agent may need to both maximise rewards and keep its reward function private from observers. Recent research presented the ambiguity model (AM), which selects actions that are ambiguous over a set of possible reward functions, via pre-trained Q-functions. Despite promising results in model-based domains, our investigation shows that AM is ineffective in model-free domains due to misdirected state space exploration. It is also inefficient to train and inapplicable in continuous action spaces. We propose the deceptive exploration ambiguity model (DEAM), which learns using the deceptive policy during training, leading to targeted exploration of the state space. DEAM is also applicable in continuous action spaces. We evaluate DEAM in discrete and continuous action space path planning environments. DEAM achieves similar performance to an optimal model-based version of AM and outperforms a model-free version of AM in terms of path cost, deceptiveness and training efficiency. These results extend to the continuous domain.

35

Itthipuripat, Sirawaj, Javier O. Garcia, and John T. Serences. "Temporal dynamics of divided spatial attention." Journal of Neurophysiology 109, no. 9 (May 1, 2013): 2364–73. http://dx.doi.org/10.1152/jn.01051.2012.

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In naturalistic settings, observers often have to monitor multiple objects dispersed throughout the visual scene. However, the degree to which spatial attention can be divided across spatially noncontiguous objects has long been debated, particularly when those objects are in close proximity. Moreover, the temporal dynamics of divided attention are unclear: is the process of dividing spatial attention gradual and continuous, or does it onset in a discrete manner? To address these issues, we recorded steady-state visual evoked potentials (SSVEPs) as subjects covertly monitored two flickering targets while ignoring an intervening distractor that flickered at a different frequency. All three stimuli were clustered within either the lower left or the lower right quadrant, and our dependent measure was SSVEP power at the target and distractor frequencies measured over time. In two experiments, we observed a temporally discrete increase in power for target- vs. distractor-evoked SSVEPs extending from ∼350 to 150 ms prior to correct (but not incorrect) responses. The divergence in SSVEP power immediately prior to a correct response suggests that spatial attention can be divided across noncontiguous locations, even when the targets are closely spaced within a single quadrant. In addition, the division of spatial attention appears to be relatively discrete, as opposed to slow and continuous. Finally, the predictive relationship between SSVEP power and behavior demonstrates that these neurophysiological measures of divided attention are meaningfully related to cognitive function.

36

Cai, Guo-Ping, and C. W. Lim. "Continuous Suboptimal Control with Partial State Feedback." Journal of Vibration and Control 11, no. 4 (April 2005): 561–78. http://dx.doi.org/10.1177/1077546305052038.

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It is well known that the classical optimal control method requires availability of all state variables of the controlled system for control feedback. This requires a measurable system, namely that all state variables may be obtained by measurement of sensors or by estimation of observers. However, some state variables in control feedback actually have a small effect on control performance. Neglecting these state variables does not greatly affect the performance of control. In this paper, we investigate a continuous suboptimal control method with partial-state feedback. First, the state variables with significant effect on the performance of control are determined using second-order sensitivity (i.e. second-order derivative of performance index with respect to control gain). Then, the suboptimal controller is designed utilizing only the determined state variables. Numerical examples are presented to demonstrate the application of the proposed control algorithm. It is shown that the relative importance of each state variable can be indicated clearly by the second-order sensitivity. The suboptimal control method presented is effective in reducing maximum responses of the structure. Furthermore, the continuous suboptimal control method may achieve almost the same level of control effectiveness as the discrete suboptimal control method.

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Ghavifekr, Amir Aminzadeh, Roberto De Fazio, Ramiro Velazquez, and Paolo Visconti. "Sensors Allocation and Observer Design for Discrete Bilateral Teleoperation Systems with Multi-Rate Sampling." Sensors 22, no. 7 (March 30, 2022): 2673. http://dx.doi.org/10.3390/s22072673.

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This study addresses sensor allocation by analyzing exponential stability for discrete-time teleoperation systems. Previous studies mostly concentrate on the continuous-time teleoperation systems and neglect the management of significant practical phenomena, such as data-swap, the effect of sampling rates of samplers, and refresh rates of actuators on the system’s stability. A multi-rate sampling approach is proposed in this study, given the isolation of the master and slave robots in teleoperation systems which may have different hardware restrictions. This architecture collects data through numerous sensors with various sampling rates, assuming that a continuous-time controller stabilizes a linear teleoperation system. The aim is to assign each position and velocity signals to sensors with different sampling rates and divide the state vector between sensors to guarantee the stability of the resulting multi-rate sampled-data teleoperation system. Sufficient Krasovskii-based conditions will be provided to preserve the exponential stability of the system. This problem will be transformed into a mixed-integer program with LMIs (linear matrix inequalities). These conditions are also used to design the observers for the multi-rate teleoperation systems whose estimation errors converge exponentially to the origin. The results are validated by numerical simulations which are useful in designing sensor networks for teleoperation systems.

38

Kalamian, Nasrin, Masoud Soltani, Fariba Bouzari Liavoli, and Mona Faraji Niri. "Observer-Based Suboptimal Controller Design for Permanent Magnet Synchronous Motors: State-Dependent Riccati Equation Controller and Impulsive Observer Approaches." Computers 13, no. 6 (June 4, 2024): 142. http://dx.doi.org/10.3390/computers13060142.

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Permanent Magnet Synchronous Motors (PMSMs) with high energy efficiency, reliable performance, and a relatively simple structure are widely utilised in various applications. In this paper, a suboptimal controller is proposed for PMSMs without sensors based on the state-dependent Riccati equation (SDRE) technique combined with customised impulsive observers (IOs). Here, the SDRE technique facilitates a pseudo-linearised display of the motor with state-dependent coefficients (SDCs) while preserving all its nonlinear features. Considering the risk of non-available/non-measurable states in the motor due to sensor and instrumentation costs, the SDRE is combined with IOs to estimate the PMSM speed and position states. Customised IOs are proven to be capable of obtaining quality, continuous estimates of the motor states despite the discrete format of the output signals. The simulation results in this work illustrate an accurate state estimation and control mechanism for the speed of the PMSM in the presence of load torque disturbances and reference speed changes. It is clearly shown that the SDRE-IO design is superior compared to the most popular existing regulators in the literature for sensorless speed control.

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Danilova, M. V., and J. D. Mollon. "Is discrimination enhanced at the boundaries of perceptual categories? A negative case." Proceedings of the Royal Society B: Biological Sciences 281, no. 1785 (June 22, 2014): 20140367. http://dx.doi.org/10.1098/rspb.2014.0367.

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The human visual system imposes discrete perceptual categories on the continuous input space that is represented by the ratios of excitations of the cones in the retina. Is discrimination enhanced at the boundaries between perceptual hues, in the way that discrimination may be enhanced at the boundaries between speech sounds in hearing? In the chromaticity diagram, the locus of unique green separates colours that appear yellowish from those that appear bluish. Using a two-alternative spatial forced choice and an adapting field equivalent to the Daylight Illuminant D65, we measured chromatic discrimination along lines orthogonal to the locus of unique green. In experimental runs interleaved with these performance measurements, we obtained estimates of the phenomenological boundary from the same observers. No enhancement of objectively measured discrimination was observed at the category boundary between yellowish and bluish hues. Instead, thresholds were minimal at chromaticities where the ratio of long-wave to middle-wave cone excitation was the same as that for the background adapting field.

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Lavenda, B. H. "Special Relativity via Modified Bessel Functions." Zeitschrift für Naturforschung A 55, no. 9-10 (October 1, 2000): 745–53. http://dx.doi.org/10.1515/zna-2000-9-1001.

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The recursive formulas of modified Bessel functions give the relativistic expressions for energy and momentum. Modified Bessel functions are solutions to a continuous time, one-dimensional discrete jump process. The jump process is analyzed from two inertial frames with a relative constant velocity; the average distance of a particle along the chain corresponds to the distance between two observers in the two inertial frames. The recursion relations of modified Bessel functions are compared to the 'k calculus' which uses the radial Doppler effect to derive relativistic kinematics. The Doppler effect predicts that the frequency is a decreasing function of the velocity, and the Planck frequency, which increases with velocity, does not transform like the frequency of a clock. The Lorentz transformation can be interpreted as energy and momentum conservation relations through the addition formula for hyperbolic cosine and sine, respectively. The addition formula for the hyperbolic tangent gives the well-known relativistic formula for the addition of velocities. In the non-relativistic and ultra-relativistic limits the distributions of the particle's position are Gaussian and Poisson, respectively.

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Bonnen, Kathryn, Alexander C. Huk, and Lawrence K. Cormack. "Dynamic mechanisms of visually guided 3D motion tracking." Journal of Neurophysiology 118, no. 3 (September 1, 2017): 1515–31. http://dx.doi.org/10.1152/jn.00831.2016.

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The continuous perception of motion-through-depth is critical for both navigation and interacting with objects in a dynamic three-dimensional (3D) world. Here we used 3D tracking to simultaneously assess the perception of motion in all directions, facilitating comparisons of responses to motion-through-depth to frontoparallel motion. Observers manually tracked a stereoscopic target as it moved in a 3D Brownian random walk. We found that continuous tracking of motion-through-depth was selectively impaired, showing different spatiotemporal properties compared with frontoparallel motion tracking. Two separate factors were found to contribute to this selective impairment. The first is the geometric constraint that motion-through-depth yields much smaller retinal projections than frontoparallel motion, given the same object speed in the 3D environment. The second factor is the sluggish nature of disparity processing, which is present even for frontoparallel motion tracking of a disparity-defined stimulus. Thus, despite the ecological importance of reacting to approaching objects, both the geometry of 3D vision and the nature of disparity processing result in considerable impairments for tracking motion-through-depth using binocular cues. NEW & NOTEWORTHY We characterize motion perception continuously in all directions using an ecologically relevant, manual target tracking paradigm we recently developed. This approach reveals a selective impairment to the perception of motion-through-depth. Geometric considerations demonstrate that this impairment is not consistent with previously observed spatial deficits (e.g., stereomotion suppression). However, results from an examination of disparity processing are consistent with the longer latencies observed in discrete, trial-based measurements of the perception of motion-through-depth.

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Corbett, Jennifer E., and Jaap Munneke. "Statistical stability and set size exert distinct influences on visual search." Attention, Perception, & Psychophysics 82, no. 2 (November 26, 2019): 832–39. http://dx.doi.org/10.3758/s13414-019-01905-2.

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AbstractDespite continuous retinal chaos, we perceive the world as stable and complete. This illusion is sustained over consecutive glances by reliance on statistical redundancies inherent in the visual environment. For instance, repeating the average size of a collection of differently sized items speeds visual search for a randomly located target regardless of trial-to-trial changes in local element size (Corbett & Melcher, 2014b). Here, we manipulate set size to investigate the potential role attention may play in these facilitative effects of statistical stability on visual search. Observers discriminated the left or right tilt of a Gabor target defined by a unique conjunction of orientation and spatial frequency in displays of Gabors with a stable or unstable mean size over successive trials. When set size was manipulated over sequences of successive trials, but held constant within a given sequence in Experiment 1, we observed distinct effects of statistical stability and attention, such that participants made faster correct responses as a function of stability and slower correct responses as a function of increasing set size. Replicating these main effects in Experiment 2, when set size was always unstable, provided converging evidence for discrete influences of statistical stability and attentional contributions to visual search. Overall, results support the proposal that our stable impressions of the surrounding environment and our abilities to attend salient events within that environment are distinctively governed by inherent statistical context and attentional processing demands.

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Khartovskii, V. E. "Estimation of the solution of asymptotically observable linear completely regular differential-algebraic systems with delay." Vestnik Udmurtskogo Universiteta. Matematika. Mekhanika. Komp'yuternye Nauki 33, no. 2 (June 2023): 329–47. http://dx.doi.org/10.35634/vm230210.

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In the article, a problem of solution estimation for linear autonomous completely regular differential-algebraic systems with many commensurate delays is investigated. The class of completely regular differential-algebraic systems with delay under study includes the classes of linear systems of delayed and neutral types; in addition, the analysis of continuous-discrete systems is reduced to completely regular systems. For linear autonomous completely regular differential-algebraic systems with many commensurate delays, the property of asymptotic observability is determined, which are characterized by the fact that all solutions generating the same output signal are indistinguishable in the future. Conditions for asymptotic observability expressed in terms of the parameters of the original system are formulated and proved. For asymptotically observable systems, a solution estimation procedure is proposed, the implementation of which consists of the following steps. First, using the observed output, a linear autonomous non-homogeneous asymptotically observable retarded type system with a non-homogeneous part depending on the output is put in correspondence with the original system. The solution of the new system uniquely determines the solution of the original system. Then a transformation is constructed that reduces the matrices of the retarded type system to a certain form. After that, with the help of a finite chain of observers, the solution is evaluated. The results of the presented study are applicable to systems that do not have the property of final observability, which makes it possible to significantly reduce the requirements for observing organs when modeling the corresponding objects of the real world.

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Andrieu, Vincent, Madiha Nadri, Ulysse Serres, and Jean-Claude Vivalda. "Continuous Discrete Observer with Updated Sampling Period." IFAC Proceedings Volumes 46, no. 23 (2013): 439–44. http://dx.doi.org/10.3182/20130904-3-fr-2041.00084.

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Mazenc, Frédéric, Saeed Ahmed, and Michael Malisoff. "Finite time estimation through a continuous-discrete observer." International Journal of Robust and Nonlinear Control 28, no. 16 (August 2, 2018): 4831–49. http://dx.doi.org/10.1002/rnc.4286.

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Lin, Kuan-Yi, Tung-Sheng Chiang, Chian-Song Chiu, Wen-Fong Hu, and Peter Liu. "Observer-Based H ∞ Fuzzy Synchronization and Output Tracking Control of Time-Varying Delayed Chaotic Systems." Journal of Mathematics 2021 (September 15, 2021): 1–21. http://dx.doi.org/10.1155/2021/5918268.

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Tracking control for the output using an observer-based H ∞ fuzzy synchronization of time-varying delayed discrete- and continuous-time chaotic systems is proposed in this paper. First, from a practical point of view, the chaotic systems here consider the influence of time-varying delays, disturbances, and immeasurable states. Then, to facilitate a uniform control design approach for both discrete- and continuous-time chaotic systems, the dynamic models along with time-varying delays and disturbances are reformulated using the T-S (Takagi–Sugeno) fuzzy representation. For control design considering immeasurable states, a fuzzy observer achieves master-slave synchronization. Third, combining both a fuzzy observer for state estimation and a controller (solved from generalized kinematic constraints) output tracking can be achieved. To make the design more practical, we also consider differences of antecedent variables between the plant, observer, and controller. Finally, using Lyapunov’s stability approach, the results are sufficient conditions represented as LMIs (linear matrix inequalities). The contributions of the method proposed are threefold: (i) systemic and unified problem formulation of master-slave synchronization and tracking control for both discrete and continuous chaotic systems; (ii) practical consideration of time-varying delay, immeasurable state, different antecedent variables (of plant, observer, and controller), and disturbance in the control problem; and (iii) sufficient conditions from Lyapunov’s stability analysis represented as LMIs which are numerically solvable observer and controller gains from LMIs. We carry out numerical simulations on a chaotic three-dimensional discrete-time system and continuous-time Chua’s circuit. Satisfactory numerical results further show the validity of the theoretical derivations.

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Berry, Mari, Brian Peacock, Bobbie Foote, and Lawrence Leemis. "Visual Assessment vs. Statistical Goodness of Fit Tests for Identifying Parent Population." Proceedings of the Human Factors Society Annual Meeting 32, no. 7 (October 1988): 460–64. http://dx.doi.org/10.1177/154193128803200701.

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Statistical tests are used to identify the parent distribution corresponding to a data set. A human observer looking at a histogram can also identify a probability distribution that models the parent distribution. The accuracy of a human observer was compared to the chi-square test for discrete data and the Kolmogorov-Smirnov and chi-square tests for continuous data. The human observer proved more accurate in identifying continuous distributions and the chi-square test proved to be superior in identifying discrete distributions. The effect of sample size and number of intervals in the histogram was included in the experimental design.

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Andrieu, Vincent, Madiha Nadri, Ulysse Serres, and Jean-Claude Vivalda. "Self-triggered continuous–discrete observer with updated sampling period." Automatica 62 (December 2015): 106–13. http://dx.doi.org/10.1016/j.automatica.2015.09.018.

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Goffaux, G., M. Remy, and A. Vande Wouwer. "Continuous–discrete confidence interval observer – Application to vehicle positioning." Information Fusion 14, no. 4 (October 2013): 541–50. http://dx.doi.org/10.1016/j.inffus.2013.02.006.

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Pengov, Marco, Edouard Richard, and Jean-Claude Vivalda. "A Continuous-Discrete Observer for a Class of Nonlinear Systems." IFAC Proceedings Volumes 31, no. 17 (July 1998): 769–74. http://dx.doi.org/10.1016/s1474-6670(17)40432-0.

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