scholarly journals Numerical and Experimental Analysis of Portable Underwater Robots with a Movable Float Device

2021 ◽  
Vol 33 (6) ◽  
pp. 1234-1247
Author(s):  
Norimitsu Sakagami ◽  
Mizuho Shibata ◽  
Tomohiro Ueda ◽  
Kensei Ishizu ◽  
Kenshiro Yokoi ◽  
...  
Keyword(s):  
Experimental Study ◽  
Feedback Control ◽  
Experimental Analysis ◽  
Field Experiments ◽  
Static Stability ◽  
Control Device ◽  
Water Tank ◽  
Underwater Robots ◽  
Stability Curve ◽  
Numerical Simulator

This report describes a numerical and experimental study of a posture control device based on a movable float for portable underwater robots. We numerically analyzed the static stability using a stability curve and allowable spatial range of a center-of-gravity shift caused by a payload shift or manipulator configuration. Further, we proposed a feedback controller based on direct pitch and roll signals to change and maintain robot posture. We tested the feedback control using a numerical simulator and conducted experiments in a water tank using two portable underwater robots to demonstrate the effectiveness of the movable float device and proposed controller. The results of the field experiments showed that the device and proposed controller can be employed for effective underwater operations of portable underwater robots.

Theoretical and experimental study of Chen chaotic system with notch filter feedback control

2010 ◽  
Vol 19 (9) ◽  
pp. 090507
Author(s):  
Zhang Xiao Ming ◽  
Chen Ju-Fang ◽  
Peng Jian-Hua
Keyword(s):  
Experimental Study ◽  
Feedback Control ◽  
Chaotic System ◽  
Notch Filter

Use of a Pendulum for Passive Structural Vibrations Control: An Experimental Study

1993 ◽  
Author(s):  
A. Ertas ◽  
O. Cuvalci
Keyword(s):  
Experimental Study ◽  
Dynamic Response ◽  
Passive Control ◽  
Control Device ◽  
Structural Vibrations ◽  
Pendulum System ◽  
Series Of Experiments ◽  
Tip Mass

Abstract The dynamic response of a beam-tip mass-pendulum system subjected to sinusoidal excitations is considered. The conditions under which resonant and nonresonant oscillations occur are investigated and discussed. The main objective of this study was to conduct a series of experiments to investigate the autoparametric interaction between the first two modes of the system. The use of a pendulum as a passive control device was experimentally evaluated.

Experimental Study of Electrical Discharge Grinding Honeycomb Tori

2012 ◽  
Vol 468-471 ◽  
pp. 924-927
Author(s):  
Ji Gao ◽  
Xiao Fang Ma ◽  
Qing Yang Liu
Keyword(s):  
Experimental Study ◽  
Experimental Analysis ◽  
Electrical Discharge ◽  
Electrical Parameters ◽  
Processing Efficiency ◽  
Technological Design ◽  
Machining Precision ◽  
Different Parts

Through the research of domestic and international aviation engine seal pieces, this paper have described the structure and technological design of electrical discharge grinding honeycomb torus. Based on experimental analysis of processing precision and processing efficiency under different electrical parameters, machining sections were designed according to the processing requirements of different parts. The results indicate that the machining precision and efficiency can be enhanced greatly.

scholarly journals Experimental Study on the Effects of a Vertical Jet Impinging on Soft Bottom Sediments

2020 ◽  
Vol 12 (9) ◽  
pp. 3775 ◽  
Author(s):  
Wei Fan ◽  
Weicheng Bao ◽  
Yong Cai ◽  
Canbo Xiao ◽  
Zhujun Zhang ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Side Effects ◽  
Field Experiments ◽  
Sediment Resuspension ◽  
Ecological Engineering ◽  
Phosphorus Release ◽  
Flow Speed ◽  
Critical Conditions ◽  
Water Tank ◽  
Flow Speeds

Artificial downwelling, which is an ecological engineering method, potentially alleviates bottom hypoxia by bringing oxygen-rich surface water down below the pycnocline. However, the downward flow is likely to disturb sediments (or induce sediment resuspension) when reaching the bottom and then have unwanted side effects on the local ecosystem. To evaluate this, our paper presents a theoretical model and experimental data for the sediment resuspension caused by artificial downwelling. The theoretical model considers the critical conditions for sediment resuspension and the scour volume with the downwelling flow disturbing sediment. Experiments with altered downwelling flow speeds, discharge positions relative to the bottom, and particle sizes of sediment were conducted in a water tank, and the results were consistent with our theoretical model. The results show that the critical Froude number (hereinafter Fr) for sediment resuspension is 0.5. The prevention of sediment resuspension requires the downwelling flow speed and the discharge position to be adjusted so that Fr < 0.5; otherwise a portion of sediment is released into the water and its volume can be predicted by the derived formulation based on the Shields theory. Furthermore, sediment resuspension has side effects, such as a water turbidity increase and phosphorus release, the magnitudes of which are discussed with respect to engineering parameters. Further study will focus on field experiments of artificial downwelling and its environmental impacts.

Computational and experimental study on dynamic behavior of underwater robots propelled by bionic undulating fins

2010 ◽  
Vol 53 (11) ◽  
pp. 2966-2971 ◽  
Author(s):  
Han Zhou ◽  
TianJiang Hu ◽  
HaiBin Xie ◽  
DaiBing Zhang ◽  
LinCheng Shen
Keyword(s):  
Experimental Study ◽  
Dynamic Behavior ◽  
Underwater Robots

scholarly journals Seismic surveying and imaging at the laboratory scale: A framework to cross-validate experiments and simulations for a salt-body environment

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. T123-T139
Author(s):  
Bence Solymosi ◽  
Nathalie Favretto-Cristini ◽  
Vadim Monteiller ◽  
Paul Cristini ◽  
Bjørn Ursin ◽  
...  
Keyword(s):  
Experimental Data ◽  
Laboratory Experiments ◽  
Field Experiments ◽  
Imaging Techniques ◽  
Laboratory Data ◽  
Seismic Exploration ◽  
Scale Model ◽  
Water Tank ◽  
Time Migration ◽  
Reduced Scale

Laboratory experiments have been recently reintroduced into the ideas-to-applications pipeline for geophysical applications. Benefiting from recent technological advances, we believe that in the coming years, laboratory experiments can play a major role in supporting field experiments and numerical modeling, to explore some of the current challenges of seismic imaging in terms of, for instance, acquisition design or benchmarking of new imaging techniques at a low cost and in an agile way. But having confidence in the quality and accuracy of the experimental data obtained in a complex configuration, which mimics at a reduced scale a real geologic environment, is an essential prerequisite. This requires a robust framework regardless of the configuration studied. Our goal is to provide a global overview of this framework in the context of offshore seismics. To illustrate it, a reduced-scale model is used to represent a 3D complex-shaped salt body buried in sedimentary layers with curved surfaces. Zero-offset and offset reflection data are collected in a water tank, using a conventional pulse-echo technique. Then, a cross-validation approach is applied, which allows us, through comparison between experimental data and the numerical simulation, to point out some necessary future improvements of the laboratory setup to increase the accuracy of the experimental data, and the limitations of the numerical implementation that must also be tackled. Due to this approach, a hierarchical list of points can be collected, to which particular attention should be paid to make laboratory experiments an efficient tool in seismic exploration. Finally, the quality of the complex reduced-scale model and the global framework is successfully validated by applying reverse time migration to the laboratory data.

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