scholarly journals Automated Insertion of Objects Into an Acoustic Robotic Gripper

Proceedings ◽  
2020 ◽  
Vol 64 (1) ◽  
pp. 40
Author(s):  
Marc Röthlisberger ◽  
Marcel Schuck ◽  
Laurenz Kulmer ◽  
Johann W. Kolar
Keyword(s):  
Acoustic Field ◽  
Acoustic Waves ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Acoustic Power ◽  
Industrial Applications ◽  
High Density ◽  
Analytical Models ◽  
Acoustic Levitation ◽  
Mechanical Contact

Acoustic levitation forces can be used to manipulate small objects and liquid without mechanical contact or contamination. To use acoustic levitation for contactless robotic grippers, automated insertion of objects into the acoustic pressure field is necessary. This work presents analytical models based on which concepts for the controlled insertion of objects are developed. Two prototypes of acoustic grippers are implemented and used to experimentally verify the lifting of objects into the acoustic field. Using standing acoustic waves and by dynamically adjusting the acoustic power, the lifting of high-density objects (>7 g/cm3) from acoustically transparent surfaces is demonstrated. Moreover, a combination of different acoustic traps is used to lift lower-density objects from acoustically reflective surfaces. The provided results open up new possibilities for the implementation of acoustic levitation in robotic grippers, which have the potential to be used in a variety of industrial applications.

scholarly journals Contactless Picking of Objects Using an Acoustic Gripper

Actuators ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 70
Author(s):  
Marc Röthlisberger ◽  
Marcel Schuck ◽  
Laurenz Kulmer ◽  
Johann W. Kolar
Keyword(s):  
Acoustic Waves ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Acoustic Power ◽  
Analytical Models ◽  
Acoustic Levitation ◽  
Medium Density ◽  
Mechanical Contact ◽  
Industrial Use ◽  
Reflective Surfaces

Acoustic levitation forces can be used to manipulate small objects and liquids without mechanical contact or contamination. This work presents analytical models based on which concepts for the controlled insertion of objects into the acoustic field are developed. This is essential for the use of acoustic levitators as contactless robotic grippers. Three prototypes of such grippers are implemented and used to experimentally verify the lifting of objects into an acoustic pressure field. Lifting of high-density objects (ρ > 7 g/cm3) from acoustically transparent surfaces is demonstrated using a double-sided acoustic gripper that generates standing acoustic waves with dynamically adjustable acoustic power. A combination of multiple acoustic traps is used to lift lower density objects (ρ≤0.25g/cm3) from acoustically reflective surfaces using a single-sided arrangement. Furthermore, a method that uses standing acoustic waves and thin reflectors to lift medium-density objects (ρ≤1g/cm3) from acoustically reflective surfaces is presented. The provided results open up new possibilities for using acoustic levitation in robotic grippers, which has the potential to be applied in a variety of industrial use cases.

Acoustic Pressure Fields Generated With a High Frequency Acoustic Levitator

2017 ◽  
Author(s):  
Michael W. Sracic ◽  
Jordan D. Petrie ◽  
Henry A. Moroder ◽  
Ryan T. Koniecko ◽  
Andrew R. Abramczyk ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Acoustic Field ◽  
Vibration Amplitude ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Mechanical Vibration ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Pressure Magnitude ◽  
Acoustic Levitator

Acoustic levitation is an advantageous particle positioning mechanism currently employed for applications of x-ray spectroscopy and micro-material manufacturing[1], [2]. By levitating a particle using only acoustic pressure waves, one eliminates the need for a container or other physical structure which may contaminate the specimen. Unfortunately, the pressure field generated by a standing acoustic wave is susceptible to periodic instabilities, and a particle that is levitated in this field tends to vibrate. The amplitude of the vibration is largest in the directions that are orthogonal to the axis in which the acoustic wave is generated. Therefore, by generating additional acoustic waves in each orthogonal axis, the vibration amplitude of the levitated particle is significantly reduced. The authors have shown this phenomenon to be true in a previous study[3]. In this paper, the authors explore the details of the pressure field that is generated with the device. A single degree-of-freedom relationship is developed between the acoustic field pressure, the location of the levitated particle, and the mechanical vibration needed to produce levitation. In order to levitate a 100 micrometer diameter water droplet at 55 kilohertz, the calculations suggest that the transducer must achieve an average surface vibration amplitude of at least 6.43 micrometers. This mechanical vibration must produce a root means-squared pressure amplitude of 933 Pascal. Under these conditions, the particle will levitate approximately 0.4 millimeters below a zero pressure node. To validate the use of the single degree of freedom relationships and to explore the acoustic field for one, two, and three-axis levitation, the authors designed and prototyped an acoustic levitator capable of generating standing waves in three orthogonal directions. Using a simple electrical control circuit, the acoustic wave transducers of each axis can be turned on individually or simultaneously. An experiment was developed to measure the pressure of the acoustic field using a microphone. Preliminary pressure magnitude results were measured for one-axis levitation along the center of the vertical axis of the levitator. The measurements suggest that the theoretical development provides a valid first approximation for the pressure magnitude and required mechanical vibration amplitude.

Predicting Bubble Migration due to Bjerknes Force in a Complex 3D Geometry: Numerical and Experimental Results

2012 ◽  
Author(s):  
Francisco I. Valentin ◽  
Silvina Cancelos
Keyword(s):  
Acoustic Field ◽  
High Speed ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Piezoelectric Materials ◽  
Bubble Diameter ◽  
Absolute Pressure ◽  
Flowing Fluid ◽  
3D Geometry ◽  
Bjerknes Force

While the Bjerknes force is not the only force experienced by a bubble subjected to an acoustic field; studies of bubble translation in non-flowing fluid have identified Bjerknes force as being the most influential. Therefore, Bjerknes force can be used to trap bubbles in predefined locations of maximum and minimum absolute pressure. Specifically challenging is to determine these locations in complex geometries because direct measurement of the acoustic pressure for the whole system is generally not possible. The objective of this research is to numerically predict Bjerknes force effect on bubble migration and accumulation in a complex 3D geometry that includes piezoelectric materials, elastic materials and a fluid media. A numerical solution of the acoustic pressure field was obtained for this geometry, valid in the range of small pressure oscillations. Additionally, using the linearized Rayleigh-Plesset equation, which gives the volumetric oscillations of a bubble subjected to an acoustic field, the Bjerknes force was numerically computed. By knowing the Bjerknes force, a bubble migration pattern upon entering the system was predicted. A CMOS high speed camera was used to experimentally monitor bubble multimode excitation and bubble response to a stationary pressure field validating our numerical results. Results are presented for experiments conducted for a 1mm bubble diameter with acoustic fields ranging from 7 to 10 kHz which correspond to values of the structure and/or the bubble’s resonant frequency.

Enhancement of Reconstruction Accuracy of the HELS Method

2002 ◽  
Author(s):  
Tatiana Semenova ◽  
Sean F. Wu
Keyword(s):  
Acoustic Field ◽  
Matrix Equation ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Back Propagation ◽  
Three Dimensional ◽  
Constrained Minimization ◽  
Reconstruction Accuracy ◽  
New Strategy ◽  
Reconstruction Point

The validity of the HELS method (Wu, 2000) for reconstructing the acoustic pressure field inside the minimum circle that encloses an arbitrary object is examined. Results show that the HELS solutions are approximate and the corresponding matrix equation is ill conditioned in general for back propagation of the acoustic field. Accordingly, the further the reconstruction point moves inside the minimum circle, the worse the reconstruction accuracy becomes. To overcome this difficulty new strategy for sensor placement is proposed. This strategy together with a constrained minimization are shown to yield satisfactory reconstruction inside the minimum circle. The same procedures can be extended to three-dimensional problems.

Instability and Sound Emission From a Flow Over a Curved Surface

1988 ◽  
Vol 110 (4) ◽  
pp. 538-544 ◽  
Author(s):  
L. Maestrello ◽  
P. Parikh ◽  
A. Bayliss
Keyword(s):  
Acoustic Waves ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Stokes Equations ◽  
Convex Surface ◽  
Two Dimensions ◽  
Navier Stokes ◽  
Sound Emission ◽  
Navier Stokes Equations ◽  
Linearized Euler Equations

The growth and decay of a wavepacket convecting in a boundary layer over a concave-convex surface is studied numerically using direct computations of the Navier-Stokes equations. The resulting sound radiation is computed using the linearized Euler equations with the pressure from the Navier-Stokes solution as a time-dependent boundary condition. It is shown that on the concave portion the amplitude of the wavepacket increases and its bandwidth broadens while on the convex portion some of the components in the packet are stabilized. The pressure field decays exponentially away from the surface and then algebraically exhibiting a decay characteristic of acoustic waves in two dimensions. The far field acoustic pressure exhibits a peak at a frequency corresponding to the inflow instability frequency.

Methodology to Identify the Unsteady Flow Field Associated With the Loss of Acoustic Energy in the Vicinity of Circular Holes

2010 ◽  
Author(s):  
Jochen Rupp ◽  
Jon Carrotte ◽  
Adrian Spencer
Keyword(s):  
Velocity Field ◽  
Flow Field ◽  
Unsteady Flow ◽  
Acoustic Field ◽  
Acoustic Waves ◽  
Large Scale ◽  
Acoustic Power ◽  
Acoustic Energy ◽  
Absorption Mechanism ◽  
Linear Absorption

Thermo-acoustic instabilities in lean gas turbine combustors have been well reported over the past decade. One option by which the generation of potentially damaging, large scale, pressure amplitudes can be avoided is to increase the amount of damping within the combustion system using passive damping devices. Common to these devices is the absorption mechanism by which acoustic energy, associated with incident pressure fluctuations onto an orifice, generates an unsteady flow that cannot be converted back into acoustic energy. This paper is concerned with providing a greater understanding of this fundamental process. Experimental results are presented for a single orifice that is exposed to plane acoustic waves within a rectangular duct. Measurements of unsteady pressure enable the acoustic power absorbed by the orifice to be determined, whilst Particle Image Velocimetry (PIV) is used to measure the unsteady flow field. A method is outlined for identifying those features within the measured unsteady flow field that are responsible for absorption of the acoustic energy. This is based on a Proper Orthogonal Decomposition (POD) analysis of the velocity field and identification of the relevant modes. The method is validated for the non-linear and linear absorption regimes by comparing the energy of the relevant velocity field features with the energy absorbed from the acoustic field. The good agreement obtained indicates the success of the technique presented. The improved understanding of the mechanisms by which energy is transferred out of the acoustic field, and into the unsteady velocity field, explains many of the observed absorption characteristics. This improved understanding should lead to the design of optimized damping systems. The presented methodology is also thought to be the basis by which numerical, CFD based, predictions relating to the absorption of acoustic waves should be analyzed and validated.

The influence of an impedance obstacle on the acoustic field inside a rectangular room

2021 ◽  
pp. 1-33
Author(s):  
Krzysztof Szemela ◽  
Wojciech P. Rdzanek
Keyword(s):  
Acoustic Field ◽  
Acoustic Waves ◽  
Acoustic Pressure ◽  
Sound Propagation ◽  
Convergent Series ◽  
Ventilation Shaft ◽  
Rectangular Obstacle ◽  
Room Model ◽  
Small Obstacle ◽  
Rectangular Room

Abstract The problem of sound propagation inside a rigid-walled room containing a rectangular obstacle was solved by dividing an acoustic field into subregions and using the continuity conditions. Acoustic waves were generated by a point source. The formulas valid for an impedance obstacle extending from a room floor to its ceiling were obtained. The considered obstacle can modeled such elements as a ventilation shaft, furniture or construction pillar. The solution was expressed in the form of convergent series. To obtain accurate results, the error resulting from the use of truncated series was controlled. Additionally, to check a correctness of the proposed solution and its computer implementation, the results obtained for a negligibly small obstacle were compared with those given by the empty room model. An excellent agreement was achieved which proves a high accuracy of the used methodology. The numerical analysis shown that the calculation time of acoustic pressure in a part of an empty room can be significantly reduced by using the obtained solution. An optimal source location for noise reduction was found. The distribution of acoustic field was illustrated and some conclusions were formulated. The changes in acoustic field due to the obstacle presence were predicted and discussed.

scholarly journals Investigation of the underwater noise produced by ships by means of intensity method

2010 ◽  
Vol 17 (3) ◽  
pp. 26-36 ◽  
Author(s):  
Eugeniusz Kozaczka ◽  
Jacek Domagalski ◽  
Ignacy Gloza
Keyword(s):  
Acoustic Field ◽  
Acoustic Waves ◽  
Acoustic Pressure ◽  
Vibration Energy ◽  
Shallow Waters ◽  
Spectral Structure ◽  
Pressure Measurements ◽  
Structural Elements ◽  
Underwater Noise ◽  
Surrounding Water

Investigation of the underwater noise produced by ships by means of intensity method This paper presents results of research on spectral structure of underwater noise acoustic field radiated into water by selected ships moving in shallow waters. Underwater acoustic field of ships in motion is associated with acoustic activity of ship mechanisms and equipment under work. Vibration energy radiated by the mechanisms and devices is transmitted by ship structural elements to surrounding water where it is propagated in the form of acoustic waves of a wide frequency band. In this paper are presented results of the research on propagation of energy of acoustic waves in the near fiel, obtained from acoustic pressure measurements by means of two sensors located close to each other.

scholarly journals A Comparison of Acoustic Field Measurement by a Microphone and by an Optical Interferometric Probe

10.14311/366 ◽  
2002 ◽  
Vol 42 (4) ◽  
Author(s):  
R. Bálek ◽  
Z. Šlegrová
Keyword(s):  
Acoustic Field ◽  
Field Measurement ◽  
Optical Method ◽  
Acoustic Pressure ◽  
Acoustic Power ◽  
Ultrasonic Frequency ◽  
Frequency Range ◽  
Harmonic Components ◽  
Laser Interferometric

The objective of this work is to show that our optical method for measuring acoustic pressure is in some way superior to measurement using a microphone. Measurement of the integral acoustic pressure in the air by a laser interferometric probe is compared with measurement using a microphone. We determined the particular harmonic components in the acoustic field in the case of relatively high acoustic power in the ultrasonic frequency range.

Improvement of the Properties of Polyethylene with Chlorinated Polyethylene (CPE)

2003 ◽  
Vol 11 (2) ◽  
pp. 115-122
Author(s):  
Kálmán Marossy ◽  
Pál Bárczy
Keyword(s):  
High Density Polyethylene ◽  
Industrial Applications ◽  
Mechanical Tests ◽  
High Density ◽  
Structural Units ◽  
Chlorinated Polyethylene ◽  
X Ray ◽  
Dynamic Mechanical ◽  
X Ray Scattering ◽  
Multiphase Systems

Blends of high density polyethylene (HDPE) and chlorinated polyethylene (CPE) have been tested across the whole concentration range. Polyethylene is used to modify the properties of CPE in the elastomer industry, but modification of the properties of polyethylene with CPE is still not usual. Conventional mechanical tests and dynamic mechanical tests were carried out. The blends were found to be multiphase systems of excellent technological compatibility. Between 10 and 15% by weight CPE increased the modulus of polyethylene. X-ray scattering studies showed that the blends contained structural units not present either in the polyethylene or in the CPE. The blends were melt processable and may have industrial applications, too.

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