Distributed Flow Sensing Using Bayesian Estimation for a Flexible Fish Robot

2015 ◽  
Author(s):  
Feitian Zhang ◽  
Francis D. Lagor ◽  
Derrick Yeo ◽  
Patrick Washington ◽  
Derek A. Paley
Keyword(s):  
Flow Model ◽  
Pressure Sensors ◽  
Estimation Algorithm ◽  
Flow Speed ◽  
The Body ◽  
Fish Robot ◽  
Flow Estimation ◽  
Flow Sensing ◽  
Time Flow ◽  
Recursive Bayesian Filter

Flexibility plays an important role in fish behaviors by enabling high maneuverability for predator avoidance and swimming in turbulence. In this paper, we present a novel, flexible fish robot equipped with distributed pressure sensors for flow sensing. The body of the robot is made of a soft, hyperelastic material that provides flexibility. The fish robot features a Joukowski-foil shape conducive to modeling the fluid analytically. A quasisteady potential-flow model is adopted for real-time flow estimation, whereas a discrete-time vortex-shedding flow model is used for higher-fidelity simulation. The dynamics for the flexible fish robot are presented, and a reduced model for one-dimensional swimming is derived. A recursive Bayesian filter assimilates pressure measurements for estimating the flow speed, angle of attack, and foil camber. Simulation and experimental results are presented to show the effectiveness of the flow estimation algorithm.

Application of PLC in the Expressway Intelligent Traffic Control System

2013 ◽  
Vol 361-363 ◽  
pp. 2219-2223
Author(s):  
Xin Hua Wei ◽  
Xian Xing Duan ◽  
Xiao Kan Wang
Keyword(s):  
Control System ◽  
Traffic Control ◽  
Flow Speed ◽  
The Body ◽  
Host Computer ◽  
Scientific Management ◽  
Traffic Lights ◽  
Traffic Control System ◽  
Vehicle Size ◽  
Sense Coil

The expressway intelligent traffic control system based on S7-200 series Programmable Logic Controller (PLC) was introduced in this paper.PLC has strong adaptability in the complex environment and rich internal timer resources, it is easily to realize accuracy controlling the traffic lights, specially for multi-crossroads.PLC analyzed and processed the signals of the body flow, speed, vehicle size and other data by the sense coil, then transmitting the information to the host computer. The host computer might automatically adjust the length of time from the final signal to achieve intelligent scientific management of traffic lights.

scholarly journals Plasma Flows in Solar Filaments as Electromagnetically Driven Vortical Flows

Physics ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 1046-1050
Author(s):  
Yuri E. Litvinenko
Keyword(s):  
Reynolds Numbers ◽  
Flow Speed ◽  
The Body ◽  
Exact Analytical Solutions ◽  
Electric And Magnetic Fields ◽  
Solar Filaments ◽  
Archimedean Force ◽  
Streaming Flows ◽  
Plasma Flow Speed ◽  
Scaling Arguments

Electromagnetic expulsion acts on a body suspended in a conducting fluid or plasma, which is subject to the influence of electric and magnetic fields. Physically, the effect is a magnetohydrodynamic analogue of the buoyancy (Archimedean) force, which is caused by the nonequal electric conductivities inside and outside the body. It is suggested that electromagnetic expulsion can drive the observed plasma counter-streaming flows in solar filaments. Exact analytical solutions and scaling arguments for a characteristic plasma flow speed are reviewed, and their applicability in the limit of large magnetic Reynolds numbers, relevant in the solar corona, is discussed.

Locomotion in scombrid fishes: visualization of flow around the caudal peduncle and finlets of the chub mackerel Scomber japonicus

2001 ◽  
Vol 204 (13) ◽  
pp. 2251-2263 ◽  
Author(s):  
Jennifer C. Nauen ◽  
George V. Lauder
Keyword(s):  
Laser Light ◽  
Light Sheet ◽  
Flow Speed ◽  
The Body ◽  
Scomber Japonicus ◽  
Laser Light Sheet ◽  
Chub Mackerel ◽  
Caudal Peduncle ◽  
Local Flow ◽  
Scombrid Fishes

SUMMARY Scombrid fishes are known for high-performance locomotion; however, few data are available on scombrid locomotor hydrodynamics. In this paper, we present flow visualization data on patterns of water movement over the caudal peduncle and finlets (small fins on the dorsal and ventral body margin anterior to the caudal fin). Chub mackerel, Scomber japonicus, ranging in fork length from 20 to 26 cm, swam steadily at 1.2forklengthss−1 in a recirculating flow tank. Small, reflective particles in the flow tank were illuminated by a vertical (xy) or horizontal (xz) laser light sheet. Patterns of flow in the region near the caudal peduncle were measured using digital particle image velocimetry. Patterns of flow along the peduncle and finlets were quantified using manual particle tracking; more than 800 particles were tracked for at least 12ms over a series of tailbeats from each of four fish. In the vertical plane, flow trajectory and flow speed were independent of the position of the finlets, indicating that the finlets did not redirect flow or affect flow speed. Along, above and below the trailing surface of the peduncle, where the finlets were oriented along the peduncular surface, flow was convergent. Along, above and below the leading surface of the peduncle, where the finlets were absent, the flow trajectory was effectively horizontal. The lack of divergent flow on the leading surface of the peduncle is consistent with cross-peduncular flow formed by the lateral motion of the peduncle interacting with convergent flow resulting from forward movement of the body. In the horizontal plane, particles illuminated by the xz light sheet situated approximately 3 mm below the ventral body surface were tracked within the laser light sheet for up to 40ms, indicating strong planar flow. As the peduncle decelerates, the most posterior finlet is frequently at an angle of attack of at least 20° to the incident flow, but this orientation does not result in thrust production from lift generation. Finlet 5 does redirect cross-peduncular flow and probably generates small vortices undetectable in this study. These data are the first direct demonstration that the finlets have a hydrodynamic effect on local flow during steady swimming.

scholarly journals Local flow sensing on helical microrobots for semi-automatic motion adaptation

2019 ◽  
Vol 39 (4) ◽  
pp. 476-489 ◽  
Author(s):  
Antoine Barbot ◽  
Dominique Decanini ◽  
Gilgueng Hwang
Keyword(s):  
Closed Loop ◽  
Flow Speed ◽  
Closed Loop Control ◽  
Flow Profile ◽  
Microfluidic Chips ◽  
Level Control ◽  
Local Flow ◽  
Loop Control ◽  
Flow Sensing ◽  
Swimming Motion

Helical microrobots with dimensions below 100 µm could serve many applications for manipulation and sensing in small, closed environments such as blood vessels or inside microfluidic chips. However, environmental conditions such as surface stiction from the channel wall or local flow can quickly result in the loss of control of the microrobot, especially for untrained users. Therefore, to automatically adapt to changing conditions, we propose an algorithm that switches between a surface-based motion of the microrobot and a 3D swimming motion depending on the local flow value. Indeed swimming is better for avoiding obstacles and difficult surface stiction areas but it is more sensitive to the flow than surface motion such as rolling or spintop motion. First, we prove the flow sensing ability of helical microrobots based on the difference between the tracked and theoretical speed. For this, a 50 µm long and 5 µm diameter helical microrobot measures the flow profile shape in two different microchannels. These measurements are then compared with simulation results. Then, we demonstrate both swimming and surface-based motion using closed-loop control. Finally, we test our algorithm by following a 2D path using closed-loop control, and adapting the type of motion depending on the flow speed measured by the microrobot. Such results could enable simple high-level control that could expand the development of microrobots toward applications in complex microfluidic environments.

scholarly journals Optical Flow Estimation with Occlusion Detection

Algorithms ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 92
Author(s):  
Song Wang ◽  
Zengfu Wang
Keyword(s):  
Optical Flow ◽  
Feature Matching ◽  
Estimation Algorithm ◽  
Occlusion Detection ◽  
Multiple Sources ◽  
Flow Estimation ◽  
Optical Flow Estimation ◽  
Dense Optical Flow ◽  
Video Frames ◽  
Optimization Function

The dense optical flow estimation under occlusion is a challenging task. Occlusion may result in ambiguity in optical flow estimation, while accurate occlusion detection can reduce the error. In this paper, we propose a robust optical flow estimation algorithm with reliable occlusion detection. Firstly, the occlusion areas in successive video frames are detected by integrating various information from multiple sources including feature matching, motion edges, warped images and occlusion consistency. Then optimization function with occlusion coefficient and selective region smoothing are used to obtain the optical flow estimation of the non-occlusion areas and occlusion areas respectively. Experimental results show that the algorithm proposed in this paper is an effective algorithm for dense optical flow estimation.

scholarly journals How Informative are the Vertical Buoyancy and the Prone Gliding Tests to Assess Young Swimmers' Hydrostatic and Hydrodynamic Profiles?

2012 ◽  
Vol 32 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Tiago Barbosa ◽  
Mário Costa ◽  
Jorge Morais ◽  
Marc Moreira ◽  
António Silva ◽  
...  
Keyword(s):  
Body Mass ◽  
Fat Mass ◽  
Flow Model ◽  
Flow Analysis ◽  
Young Male ◽  
The Body ◽  
Mean Square ◽  
Analysis Model ◽  
Stroke Length ◽  
Stroke Frequency

How Informative are the Vertical Buoyancy and the Prone Gliding Tests to Assess Young Swimmers' Hydrostatic and Hydrodynamic Profiles? The aim of this research was to develop a path-flow analysis model to highlight the relationships between buoyancy and prone gliding tests and some selected anthropometrical and biomechanical variables. Thirty-eight young male swimmers (12.97 ± 1.05 years old) with several competitive levels were evaluated. It were assessed the body mass, height, fat mass, body surface area, vertical buoyancy, prone gliding after wall push-off, stroke length, stroke frequency and velocity after a maximal 25 [m] swim. The confirmatory model included the body mass, height, fat mass, prone gliding test, stroke length, stroke frequency and velocity. All theoretical paths were verified except for the vertical buoyancy test that did not present any relationship with anthropometrical and biomechanical variables nor with the prone gliding test. The good-of-fit from the confirmatory path-flow model, assessed with the standardized root mean square residuals (SRMR), is considered as being close to the cut-off value, but even so not suitable of the theory (SRMR = 0.11). As a conclusion, vertical buoyancy and prone gliding tests are not the best techniques to assess the swimmer's hydrostatic and hydrodynamic profile, respectively.

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