Synchronization engineering: tuning the phase relationship between dissimilar oscillators using nonlinear feedback

2010 ◽  
Vol 368 (1918) ◽  
pp. 2189-2204 ◽  
Author(s):  
Craig G. Rusin ◽  
Hiroshi Kori ◽  
István Z. Kiss ◽  
John L. Hudson
Keyword(s):  
Phase Difference ◽  
Phase Relationship ◽  
Feedback Signal ◽  
Experimental Measurements ◽  
Feedback Delay ◽  
Nonlinear Feedback ◽  
Interaction Function ◽  
Dynamical Properties ◽  
Phase Models ◽  
Time Delayed Feedback

A mild, nonlinear, time-delayed feedback signal was applied to two heterogeneous oscillators in order to synchronize their frequencies with an arbitrary and controllable phase difference. The feedback was designed using phase models constructed from experimental measurements of the intrinsic dynamical properties of the oscillators. The feedback signal produced an interaction function that corresponds to the desired collective behaviour. The synchronized phase difference between the elements can be tuned to any value on the interval 0 and 2 π by shifting the phase of the interaction function using the feedback delay. Numerical simulations were conducted and experiments carried out with electrochemical oscillators.

EquiTest modification with shank and hip angle measurements: differences with age among normal subjects

1999 ◽  
Vol 9 (6) ◽  
pp. 435-444
Author(s):  
Rosemary A. Speers ◽  
Neil T. Shepard ◽  
Arthur D. Kuo
Keyword(s):  
Age Groups ◽  
Phase Relationship ◽  
Normal Subjects ◽  
Body Sway ◽  
Feedback Signal ◽  
Proprioceptive Information ◽  
Sensory Organization Test ◽  
Test Protocol ◽  
Ankle Motion ◽  
Sensory Organization

The Sensory Organization Test protocol of the EquiTest system (NeuroCom International, Clackamas Oregon) tests utilization of visual, vestibular, and proprioceptive sensors by manipulating the accuracy of visual and/or somatosensory inputs during quiet stance. In the standard Sensory Organization Test, both manipulation of sensory input (sway-referencing) and assessment of postural sway are based on ground reaction forces measured from a forceplate. The purpose of our investigation was to examine the use of kinematic measurements to provide a more direct feedback signal for sway-referencing and for assessment of sway. We compared three methods of sway-referencing: the standard EquiTest method based on ground reaction torque, kinematic feedback based on servo-controlling to shank motion, and a more complex kinematic feedback based on servo-controlling to follow position of the center of mass (COM) as calculated from a two-link biomechanical model. Fifty-one normal subjects (ages 20–79) performed the randomized protocol. When using either shank or COM angle for sway-referencing feedback as compared to the standard EquiTest protocol, the Equilibrium Quotient and Strategy Score assessments were decreased for all age groups in the platform sway-referenced conditions (SOT 4, 5, 6). For all groups of subjects, there were significant differences in one or more of the kinematic sway measures of shank, hip, or COM angle when using either of the alternative sway-referencing parameters as compared to the standard EquiTest protocol. The increased sensitivities arising from use of kinematics had the effect of amplifying differences with age. For sway-referencing, the direct kinematic feedback may enhance ability to reduce proprioceptive information by servo-controlling more closely to actual ankle motion. For assessment, kinematics measurements can potentially increase sensitivity for detection of balance disorders, because it may be possible to discriminate between body sway and acceleration and to determine the phase relationship between ankle and hip motion.

scholarly journals Pressure Control of Insulation Space for Liquefied Natural Gas Carrier with Nonlinear Feedback Technique

2018 ◽  
Vol 6 (4) ◽  
pp. 133
Author(s):  
Jinghua Cao ◽  
Xianku Zhang ◽  
Xiang Zou
Keyword(s):  
Natural Gas ◽  
Control Strategy ◽  
Control Strategies ◽  
Nonlinear Function ◽  
Pressure Control ◽  
Feedback Signal ◽  
Control Input ◽  
Nonlinear Feedback ◽  
Pressure Control System ◽  
Liquid Natural Gas

This paper introduces a novel control strategy into the insulation space for liquid natural gas carriers. The control strategy proposed can improve the effects of control for differential pressure and reduce the energy consumption of nitrogen. The method combines a nonlinear feedback technique with a closed-loop gain shaping algorithm (CGSA). It is designed for the pressure control system which is vital for liquid natural gas carriers (LNGCs) in marine transportation. The control error is modulated using nonlinear function. The deviation signal is replaced with a nonlinear feedback signal. Comparison experiments are conducted under different conditions to prove the effectiveness of this strategy. This paper compares three control strategies: a control strategy with nonlinear feedback based on CGSA, a control strategy without nonlinear feedback based on CGSA, and a two-degree-of-freedom (DOF) control strategy. The simulation results show that this control strategy with nonlinear feedback performs better than the other two. The average reduction of control input is about 38.8%. The effect of pressure control is satisfactory.

Dynamic Nonlinear Feedback Control Applied to Improve Butanol Production by Clostridium acetobutylicum

2017 ◽  
Vol 15 (6) ◽  
Author(s):  
H. I Velázquez-Sánchez ◽  
G. Lara-Cisneros ◽  
R. Femat ◽  
R. Aguilar-López
Keyword(s):  
Clostridium Acetobutylicum ◽  
Numerical Experiments ◽  
Closed Loop ◽  
Open Loop ◽  
Feedback Signal ◽  
Butanol Production ◽  
Nonlinear Feedback ◽  
Operational Conditions ◽  
Continuous Bioreactor ◽  
Control Scheme

Abstract The goal of this work is to present a closed-loop operational strategy in order to improve the butanol production in an anaerobic continuous bioreactor for the called Acetone-Butanol-Ethanol (ABE) process. The proposed control scheme considers a class of feedback signal which includes a nonlinear bounded function of the regulation error. The control scheme is applied to a phenomenological unstructured kinetic model obtained from an experimental and metabolic study of butanol production by Clostridium acetobutylicum, which allows the proposed structure to predict several operational conditions from batch and continuous regimes. Numerical experiments using the proposed model considering continuous operation were performed in order to find a feasible operating region for maximum butanol production at open-loop regime. The proposed methodology is applied to regulate the product concentration, manipulating the dilution rate to lead to a higher butanol productivity. The closed-loop behaviour of the bioreactor is analysed, finding that the proposed controller minimizes the response time of the system and allows it to achieve a productivity gain of 55 % over open-loop operation. Further numerical experiments show the satisfactory closed-loop performance of the proposed methodology in comparison with a PI controller.

scholarly journals Design of Ship Course-Keeping Autopilot using a Sine Function-Based Nonlinear Feedback Technique

2015 ◽  
Vol 69 (2) ◽  
pp. 246-256 ◽  
Author(s):  
Xian-ku Zhang ◽  
Guo-qing Zhang
Keyword(s):  
Control Strategies ◽  
Feedback Signal ◽  
Sine Function ◽  
Nonlinear Feedback ◽  
Control Effect ◽  
Control Error ◽  
Closed Loop Systems ◽  
Automatic Navigation ◽  
Feedback Scheme ◽  
Control Scheme

Course keeping for ships is the core of automatic navigation in sea transportation. Much work has concentrated on developing novel control strategies for closed loop systems. We have turned our attention the other way to improve the control performance of marine autopilots in this work by “modulating” the control error using a sine function while the construction of the controller is not changed. The nonlinear feedback signal thus obtained is sent to the controller to replace the control error itself, which used to be the deviation between the output response and the reference input of the system. Such a control scheme is called “nonlinear feedback control” hereafter. Theoretical analysis by using a describing function and robust control theory shows that the same control quality is guaranteed with minor control actions for the nonlinear feedback scheme. Simulation experiments were carried out for the ship Yulong of Dalian Maritime University. It is shown that the method postulated in this paper has advantages of safety and energy saving in navigation; the maximum initial rudder angle is reduced by 31·2% with satisfactory control effect.

Computation of Wave-Induced Drift Forces Introduced by Displaced Position of Compliant Offshore Platforms

1992 ◽  
Vol 114 (3) ◽  
pp. 175-184 ◽  
Author(s):  
Y. Li ◽  
A. Kareem
Keyword(s):  
Time Domain ◽  
Phase Relationship ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Offshore Structures ◽  
Time Dependent ◽  
Wave Loads ◽  
Nonlinear Feedback ◽  
The Time Domain ◽  
Drift Forces

The wave forces computed at the displaced position of offshore structures may introduce additional drift forces. This contribution is particularly significant for compliant offshore structures that are configured by design to experience large excursions under the environmental load effects, e.g., tension leg platform. In a random sea environment, this feature can be included in the time domain analysis by synthesizing drag and diffraction forces through a summation of a large number of harmonics with an appropriate phase relationship that reflects the platform displaced position. This approach is not only limited to the time domain analysis, but the superposition of a large number of trigonometric terms in such an analysis requires a considerable computational effort. This paper presents a computationally efficient procedure in both the time and frequency domains that permits inclusion of the time-dependent drift forces, introduced by the platform displacement, in terms of linear and nonlinear feedback contributions. These time-dependent feedback forces are expressed in terms of the applied wave loads by linear and quadratic transformations. It is demonstrated that the results obtained by this approach exhibit good agreement with the procedure based on the summation of trigonometric functions.

Control of Economic Situations by Utilizing an Electronic Circuit

2015 ◽  
Vol 3 (2) ◽  
pp. 1-15
Author(s):  
S.G. Stavrinides ◽  
M.P. Hanias ◽  
L. Magafas ◽  
S. Banerjee
Keyword(s):  
Dynamical System ◽  
Simple Form ◽  
Delay Time ◽  
Physical System ◽  
Electronic Circuit ◽  
Chaotic Behavior ◽  
Feedback Delay ◽  
System Variable ◽  
And Control ◽  
Time Delayed Feedback

In this paper a circuit (physical system), implementing a financial system with time-delayed feedbacks, is designed and studied. The simple form of this dynamical system, without any time-delayed feed, has been already investigated and was found to demonstrate both a periodic and chaotic behavior. By introducing the time-delayed feedback, according to the Pyragas method, control of the circuit's-system's chaotic behaviour could be achieved. Its overall operation was simulated, using NI's Multisim and control of its behaviour was achieved by controlling feedback delay-time of a certain system variable, corresponding to a financial variable.

Complex Dynamic Behavior in a Model of Electro-Optic Device with Time-Delayed Feedback

1998 ◽  
Vol 08 (06) ◽  
pp. 1347-1354 ◽  
Author(s):  
Andrew V. Shobukhov
Keyword(s):  
Hopf Bifurcation ◽  
Numerical Investigation ◽  
Infinite Number ◽  
Strain Gauge ◽  
Fiber Optic ◽  
Equilibrium Points ◽  
Nonlinear Feedback ◽  
Complex Dynamic ◽  
Electro Optic ◽  
Time Delayed Feedback

Oscillatory and chaotic regimes arising from Andronov-Hopf bifurcation are obtained in a model of fiber-optic interferometric strain gauge with delayed nonlinear feedback as a result of analytical and numerical investigation. Complicated behavior of solutions in the case of infinite number of equilibrium points is reported.

Experimental Investigation of the Influence of External Vibrations on Coriolis Mass Flow Meters

2002 ◽  
Author(s):  
Robert Cheesewright ◽  
Colin Clark
Keyword(s):  
Phase Difference ◽  
Mechanical Design ◽  
Phase Relationship ◽  
Working Fluid ◽  
Drive Frequency ◽  
Displacement Sensors ◽  
Cold Room ◽  
Wide Range ◽  
Complete Study ◽  
Sensor Signals

The Coriolis flow meter is basically a vibrating tube device; it is therefore potentially susceptible to disruption by external vibrations transmitted from the environment in which the meter is mounted. The paper reports the findings from a carefully structured experimental study in which the results of both analysis and numerical simulation studies were used to guide the choice of vibration frequencies and the directions and the spatial distributions of the vibrations. The total of eight different meters from five different manufacturers covered a wide range of meter geometries and drive frequencies. In addition to comparisons of the flow rates indicated by the meters with independent measures of the flow rate, all the tests involved the recording of raw signals from the displacement sensors so that the effects of using different techniques to extract the phase relationship between these signals could be investigated. All the tests were performed using cold (room temperature) water as the working fluid. The results of the study show that vibrations at the meter drive frequency caused errors in all meters. Vibrations at other frequencies also caused errors in several meters but these errors appear to be due to the algorithm (implemented in the meter electronics) used to extract the phase difference (the measurand) between the sensor signals. However, the complete study suggests that, by suitable choices of meter mechanical design and of the algorithm used to determine the phase difference, it is possible to make a meter which is unaffected by vibrations at any frequency other than the meter drive frequency (provided only that the meter tube motion produced by the vibration is smaller than that produced by the meter drive). For vibrations at the drive frequency the results show that (in general agreement with the analytical and numerical studies) the magnitude of the error depends on the phase relationship between the imposed vibration and the meter drive. Errors also depend on the spatial distribution of the vibration (e.g. the error is different for the same amplitude of vibration applied uniformly to a meter and applied to one end only of the meter). Methods for reducing drive frequency errors are discussed but it is concluded that it may not be possible to eliminate these errors completely.

scholarly journals Anti-phase collective synchronization with intrinsic in-phase coupling of two groups of electrochemical oscillators

2019 ◽  
Vol 377 (2160) ◽  
pp. 20190095 ◽  
Author(s):  
Michael Sebek ◽  
Yoji Kawamura ◽  
Ashley M. Nott ◽  
István Z. Kiss
Keyword(s):  
Phase Difference ◽  
Phase Synchronization ◽  
Single Pair ◽  
Phase Coupling ◽  
Dynamical Interaction ◽  
Phase Dynamics ◽  
Internal Phase ◽  
Phase Models ◽  
External Coupling ◽  
Internal Coupling

The synchronization of two groups of electrochemical oscillators is investigated during the electrodissolution of nickel in sulfuric acid. The oscillations are coupled through combined capacitance and resistance, so that in a single pair of oscillators (nearly) in-phase synchronization is obtained. The internal coupling within each group is relatively strong, but there is a phase difference between the fast and slow oscillators. The external coupling between the two groups is weak. The experiments show that the two groups can exhibit (nearly) anti-phase collective synchronization. Such synchronization occurs only when the external coupling is weak, and the interactions are delayed by the capacitance. When the external coupling is restricted to those between the fast and the slow elements, the anti-phase synchronization is more prominent. The results are interpreted with phase models. The theory predicts that, for anti-phase collective synchronization, there must be a minimum internal phase difference for a given shift in the phase coupling function. This condition is less stringent with external fast-to-slow coupling. The results provide a framework for applications of collective phase synchronization in modular networks where weak coupling between the groups can induce synchronization without rearrangements of the phase dynamics within the groups. This article is part of the theme issue ‘Coupling functions: dynamical interaction mechanisms in the physical, biological and social sciences’.

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