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.

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.

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.

scholarly journals Some Remarks Concerning Jones Eigenfrequencies and Jones Modes

2005 ◽  
Vol 12 (2) ◽  
pp. 337-348
Author(s):  
David Natroshvili ◽  
Guram Sadunishvili ◽  
Irine Sigua
Keyword(s):  
Exterior Domain ◽  
Thermal Stresses ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Three Dimensional ◽  
Boundary Surface ◽  
Isotropic Body ◽  
Oscillation Parameter ◽  
Uniqueness Of Solutions ◽  
Fluid Solid Interaction

Abstract Three-dimensional fluid-solid interaction problems with regard for thermal stresses are considered. An elastic structure is assumed to be a bounded homogeneous isotropic body occupying a domain , where the thermoelastic four dimensional field is defined, while in the unbounded exterior domain there is defined the scalar (acoustic pressure) field. These two fields satisfy the differential equations of steady state oscillations in the corresponding domains along with the transmission conditions of special type on the interface ∂Ω±. We show that uniqueness of solutions strongly depends on the geometry of the boundary ∂Ω±. In particular, we prove that for the corresponding homogeneous transmission problem for a ball there exist infinitely many exceptional values of the oscillation parameter (Jones eigenfrequencies). The corresponding eigenvectors (Jones modes) are written explicitly. On the other hand, we show that if the boundary surface ∂Ω± contains two flat, non-parallel sub-manifolds then there are no Jones eigenfrequencies for such domains.

scholarly journals Acoustic fields and microfluidic patterning around embedded micro-structures subject to surface acoustic waves

Soft Matter ◽  
2019 ◽  
Vol 15 (43) ◽  
pp. 8691-8705 ◽  
Author(s):  
David J. Collins ◽  
Richard O’Rorke ◽  
Adrian Neild ◽  
Jongyoon Han ◽  
Ye Ai
Keyword(s):  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Analytical Models ◽  
Acoustic Fields ◽  
Micro Structures ◽  
Microfluidic Patterning

Interactions between substrate waves and microchannel walls generate spatially localized periodic acoustic forces for microscale patterning activities. We develop analytical models that can be readily applied to predict this periodicity.

scholarly journals Acoustophoretic Control of Microparticle Transport Using Dual-Wavelength Surface Acoustic Wave Devices

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 52 ◽  
Author(s):  
Jin-Chen Hsu ◽  
Chih-Hsun Hsu ◽  
Yeo-Wei Huang
Keyword(s):  
Particle Motion ◽  
Acoustic Waves ◽  
Acoustic Pressure ◽  
Acoustic Radiation ◽  
Surface Acoustic Waves ◽  
Microfluidic Channel ◽  
Radiation Force ◽  
Dual Wavelength ◽  
Single Frequency ◽  
Motion Trajectories

We present a numerical and experimental study of acoustophoretic manipulation in a microfluidic channel using dual-wavelength standing surface acoustic waves (SSAWs) to transport microparticles into different outlets. The SSAW fields were excited by interdigital transducers (IDTs) composed of two different pitches connected in parallel and series on a lithium niobate substrate such that it yielded spatially superimposed and separated dual-wavelength SSAWs, respectively. SSAWs of a singltablee target wavelength can be efficiently excited by giving an RF voltage of frequency determined by the ratio of the velocity of the SAW to the target IDT pitch (i.e., f = cSAW/p). However, the two-pitch IDTs with similar pitches excite, less efficiently, non-target SSAWs with the wavelength associated with the non-target pitch in addition to target SSAWs by giving the target single-frequency RF voltage. As a result, dual-wavelength SSAWs can be formed. Simulated results revealed variations of acoustic pressure fields induced by the dual-wavelength SSAWs and corresponding influences on the particle motion. The acoustic radiation force in the acoustic pressure field was calculated to pinpoint zero-force positions and simulate particle motion trajectories. Then, dual-wavelength SSAW acoustofluidic devices were fabricated in accordance with the simulation results to experimentally demonstrate switching of SSAW fields as a means of transporting particles. The effects of non-target SSAWs on pre-actuating particles were predicted and observed. The study provides the design considerations needed for the fabrication of acoustofluidic devices with IDT-excited multi-wavelength SSAWs for acoustophoresis of microparticles.

An alternative approach for measuring the scattered acoustic pressure field of immersed single and multiple cylinders

2011 ◽  
Vol 57 (3) ◽  
pp. 411-419 ◽  
Author(s):  
Sina Sodagar ◽  
Farhang Honarvar ◽  
Amin Yaghootian ◽  
Anthony N. Sinclair
Keyword(s):  
Acoustic Pressure ◽  
Pressure Field ◽  
Alternative Approach

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.

Effect of Shear Layer Interaction on Acoustic Response of Coaxial Side Branch Resonators

2007 ◽  
Author(s):  
P. Oshkai ◽  
A. Velikorodny ◽  
T. Yan
Keyword(s):  
Shear Layer ◽  
Acoustic Waves ◽  
Acoustic Power ◽  
Shear Layers ◽  
Side Branch ◽  
Acoustic Response ◽  
Quality Factors ◽  
Hydrodynamic Modes ◽  
Layer Interaction ◽  
Turbulent Inflow

Fully turbulent inflow past a coaxial side branch resonator mounted in a duct can give rise to pronounced flow oscillations due to coupling between separated shear layers and standing acoustic waves. Experimental investigation of acoustically-coupled shear layers is conducted using digital particle image velocimetry in conjunction with unsteady pressure measurements. Global instantaneous flow images, as well as phase-averaged images, are evaluated to provide insight into the flow physics during tone generation. The emphasis is on the effect of shear layer interaction on the acoustic response of the resonator during the first and second hydrodynamic modes of the shear layer oscillation. Onset of the locked-on resonant states is characterized in terms of the acoustic pressure amplitudes and the quality factors of the corresponding spectral peaks. Moreover, patterns of generated acoustic power are calculated using a semi-empirical approach. As the level of interaction between the separated shear layers is increased, spatial structure of the acoustic source undergoes a substantial transformation.

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.

Sign in / Sign up

Export Citation Format

Share Document