scholarly journals Usage of phase portraits in analysis of doppler signals reflected from drone rotors

2020 ◽  
Vol 25 (4) ◽  
pp. 18-29
Author(s):  
R. Pashchenko ◽  
◽  
V. Ivanov ◽  
D. Tsyupak
Keyword(s):  
Time Delay ◽  
Phase Portrait ◽  
Time Delays ◽  
Rotational Velocity ◽  
Phase Portraits ◽  
Image Point ◽  
Value Of Time ◽  
Doppler Signals ◽  
Signal Period ◽  
Similar Phase

Subject and Purpose. Comparative analysis of the shapes of phase portraits of Doppler signals (DS) reflected from drone rotating rotors is given with regard to different time delays. The shapes of DS phase portraits are examined for various rotational velocities and numbers of the rotating rotors. Methods and Methodology. A method using phase portraits is suggested for analysis of Doppler signals reflected from drone rotating rotors. The method determines the number of the rotors and estimates their rotational velocities. Results. It has been found that the shape of the phase portrait of the baseline signal is practically independent of the time delay and can be described as an occasional movement of the image point following the phase trajectory in the center of the phase portrait. The appearance of characteristic regions on the periphery of the phase portrait allows separating baseline and sounding signals. It has been shown that the shape of the DS phase portrait of the rotating rotor during the flight movement of the drone depends on the time delay value. With a larger delay, phase portraits similar in shape appear at regular intervals equal to the Doppler signal period. With a larger rotational velocity of the rotor, the rate of similar phase portrait appearance diminishes. Conclusion. During the sounding of drone rotating rotors, the shapes of DS phase portraits depend on the value of time delay. With a larger number of rotors in the drone flight, the periodic change character as to the DS phase portrait shape remains unchanged. In this case, DS phase portrait shapes differ substantially for different numbers of drone rotors

scholarly journals Delay-Dependent Robust Stabilization for Nonlinear Large Systems via Decentralized Fuzzy Control

2011 ◽  
Vol 2011 ◽  
pp. 1-20 ◽  
Author(s):  
Chun-xia Dou ◽  
Zhi-sheng Duan ◽  
Xing-bei Jia ◽  
Xiao-gang Li ◽  
Jin-zhao Yang ◽  
...  
Keyword(s):  
Time Delay ◽  
Fuzzy Control ◽  
Upper Bound ◽  
Time Delays ◽  
Sufficient Conditions ◽  
Large System ◽  
Disturbance Attenuation ◽  
Robust Controller ◽  
Large Systems ◽  
Delay Dependent

A delay-dependent robust fuzzy control approach is developed for a class of nonlinear uncertain interconnected time delay large systems in this paper. First, an equivalent T–S fuzzy model is extended in order to accurately represent nonlinear dynamics of the large system. Then, a decentralized state feedback robust controller is proposed to guarantee system stabilization with a prescribedH∞disturbance attenuation level. Furthermore, taking into account the time delays in large system, based on a less conservative delay-dependent Lyapunov function approach combining with linear matrix inequalities (LMI) technique, some sufficient conditions for the existence ofH∞robust controller are presented in terms of LMI dependent on the upper bound of time delays. The upper bound of time-delay and minimizedH∞performance index can be obtained by using convex optimization such that the system can be stabilized and for all time delays whose sizes are not larger than the bound. Finally, the effectiveness of the proposed controller is demonstrated through simulation example.

scholarly journals Methods for broadband signals mutual time delays estimating enhancement

2019 ◽  
Vol 30 ◽  
pp. 03012
Author(s):  
Ilya Grin ◽  
Oleg Morozov
Keyword(s):  
Time Delay ◽  
Computational Efficiency ◽  
Radiation Source ◽  
Time Delays ◽  
Time Delay Estimation ◽  
Ambiguity Function ◽  
Delay Estimation ◽  
Reliability Criterion ◽  
Optimal Processing ◽  
Narrowband Channels

This paper considers methods for estimating the mutual time delay of broadband signals recorded by satellites based multi-position systems for determining the location of a radiation source. All methods considered are based on modified algorithms for calculating the ambiguity function. The presented algorithms are based on the extraction of narrowband channels from the studied signals and their further optimal processing. The reliability criterion for mutual time delay estimation by the presented methods was evaluated. Based on the results and analysis of computational efficiency, viability of methods considered and their modifications was determined.

Time-Intensity Trade for Speech: A Temporal Speech-Stenger Effect

1976 ◽  
Vol 19 (4) ◽  
pp. 749-766 ◽  
Author(s):  
Michael J.M. Raffin ◽  
David J. Lilly ◽  
Aaron R. Thornton
Keyword(s):  
Time Delay ◽  
Clinical Application ◽  
Time Delays ◽  
Multiple Images ◽  
Potential Clinical Application ◽  
Interaural Time Delay ◽  
Lateralization Effect

Time-intensity trade for selected spondaically stressed words was investigated using a centering method for interaural time delays of 0.00, 1.00, 2.00, 2.25, 2.50, and 2.75 msec at five levels of presentation: 0-, 25-, 40-, 55-, and 70-dB HL (ANSI, 1969). Lateralization effects increased with level of presentation, with a maximum lateralization effect of between 22 and 30 dB occuring with an interaural time delay of 2.25 msec. Multiple images were perceived by all subjects with an interaural time delay of 2.75 msec and by some subjects with an interaural time delay of 2.50 msec at high levels of presentation. No “ear effect” was observed for any of the listeners. A potential clinical application is discussed for this temporal speech-Stenger effect.

scholarly journals Ambiguities in gravitational lens models: impact on time delays of the source position transformation

2018 ◽  
Vol 617 ◽  
pp. A140 ◽  
Author(s):  
Olivier Wertz ◽  
Bastian Orthen ◽  
Peter Schneider
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Hubble Constant ◽  
Companion Paper ◽  
Gravitational Lens ◽  
Source Position ◽  
Double Image ◽  
Validity Criterion ◽  
Mass Profile ◽  
Image Pairs

The central ambition of the modern time delay cosmography consists in determining the Hubble constant H0 with a competitive precision. However, the tension with H0 obtained from the Planck satellite for a spatially flat ΛCDM cosmology suggests that systematic errors may have been underestimated. The most critical of these errors probably comes from the degeneracy existing between lens models that was first formalized by the well-known mass-sheet transformation (MST). In this paper, we assess to what extent the source position transformation (SPT), a more general invariance transformation which contains the MST as a special case, may affect the time delays predicted by a model. To this aim, we have used pySPT, a new open-source python package fully dedicated to the SPT that we present in a companion paper. For axisymmetric lenses, we find that the time delay ratios between a model and its SPT-modified counterpart simply scale like the corresponding source position ratios, Δtˆ/Δt ≈ βˆ/β, regardless of the mass profile and the isotropic SPT. Similar behavior (almost) holds for nonaxisymmetric lenses in the double image regime and for opposite image pairs in the quadruple image regime. In the latter regime, we also confirm that the time delay ratios are not conserved. In addition to the MST effects, the SPT-modified time delays deviate in general no more than a few percent for particular image pairs, suggesting that its impact on time delay cosmography seems not be as crucial as initially suspected. We also reflected upon the relevance of the SPT validity criterion and present arguments suggesting that it should be reconsidered. Even though a new validity criterion would affect the time delays in a different way, we expect from numerical simulations that our conclusions will remain unchanged.

Super-Resolution Time-Delays Estimation in HF Channel Sounding Based on Chirp Sequence

2011 ◽  
Vol 204-210 ◽  
pp. 2133-2139
Author(s):  
Long Fei Fu ◽  
Gang Xin ◽  
Shui Lian Zhang
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Measurement Data ◽  
Super Resolution ◽  
Wide Band ◽  
Estimation Problem ◽  
Delay Model ◽  
Music Algorithm ◽  
Problem Of Time ◽  
Hf Channel

According to the characteristics of HF channel and chirp signal, an innovative multipath time-delay model of wide-band HF channel was proposed, by which the estimation problem of time-delay was converted into an estimation problem of spectrum.Then the MUSIC algorithm with super-resolution ability was applied to the problem above. The feasibility of estimating multipath time-delays based on single measurement data was deeply discussed. Meanwhile, the performance of applying MUSIC and root MUSIC algorithm to the model proposed in the paper was presented. The simulation results suggested that the method proposed in the paper owned super-resolution ability and robust in estimation of multipath time-delay.

Analytical and Experimental Predictor-Based Time Delay Control of Baxter Robot

2018 ◽  
Author(s):  
Mostafa Bagheri ◽  
Miroslav Krstić ◽  
Peiman Naseradinmousavi
Keyword(s):  
Time Delay ◽  
Time Delays ◽  
Input Delay ◽  
Delay Systems ◽  
Engineering Systems ◽  
Common Control ◽  
Pick And Place ◽  
Place Task ◽  
Input Delays ◽  
Time Invariant

In this paper, a predictor-based controller for a 7-DOF Baxter manipulator is formulated to compensate a time-invariant input delay during a pick-and-place task. Robot manipulators are extensively employed because of their reliable, fast, and precise motions although they are subject to large time delays like many engineering systems. The time delay may lead to the lack of high precision required and even catastrophic instability. Using common control approaches on such delay systems can cause poor control performance, and uncompensated input delays can produce hazards when used in engineering applications. Therefore, destabilizing time delays need to be regarded in designing control law. First, delay-free dynamic equations are derived using the Lagrangian method. Then, we formulate a predictor-based controller for a 7-DOF Baxter manipulator, in the presence of input delay, in order to track desirable trajectories. Finally, the results are experimentally evaluated.

DYNAMICS AND DOUBLE HOPF BIFURCATIONS OF THE ROSE–HINDMARSH MODEL WITH TIME DELAY

2009 ◽  
Vol 19 (11) ◽  
pp. 3733-3751 ◽  
Author(s):  
SUQI MA ◽  
ZHAOSHENG FENG ◽  
QISHAI LU
Keyword(s):  
Hopf Bifurcation ◽  
Time Delay ◽  
Center Manifold ◽  
Hopf Bifurcations ◽  
Value Of Time ◽  
Asymptotically Stable ◽  
Universal Unfolding ◽  
Double Hopf Bifurcation ◽  
Bifurcation Points ◽  
The Rose

In this paper, we are concerned with the Rose–Hindmarsh model with time delay. By applying the generalized Sturm criterion, a number of imaginary roots of the characteristic equation are classified. The absolutely stable regions for any value of time delay are detected. By the continuous software DDE-Biftool, both the Hopf bifurcation curves and double Hopf bifurcation points are illustrated in parametric spaces. The normal form and universal unfolding at double Hopf bifurcation points are considered by the center manifold method. Some examples also indicate that the corresponding unique attractor near each double Hopf point is asymptotically stable.

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