Design, Analysis, and Optimization of a New Two-DOF Articulated Multi-Link Robotic Tail

2019 ◽  
Author(s):  
Yujiong Liu ◽  
Pinhas Ben-Tzvi
Keyword(s):  
Kinematic Model ◽  
Low Frequency ◽  
Detailed Design ◽  
Frequency Responses ◽  
Transmission Design ◽  
Redundant Design ◽  
Hybrid Mechanism ◽  
Single Link ◽  
Inertial Loading ◽  
Design Challenges

Abstract Based on observations from nature, tails are believed to help animals achieve highly agile motions. Traditional single-link robotic tails serve as a good simplification for both modeling and implementation purposes. However, this approach cannot explain the complicated tail behaviors exhibited in nature where multi-link structures are more commonly observed. Unlike its single-link counterpart, articulated multi-link tails essentially belong to the serial manipulator family which possesses special transmission design challenges. To address this challenge, a cable driven hyper-redundant design becomes the most used approach. Limited by cable strength and elastic components, this approach suffers from low frequency responses, inadequate generated inertial loading, and fragile hardware, which are all critical drawbacks for robotic tails design. To solve these structure related shortcomings, a multi-link robotic tail made up of rigid links is proposed in this paper. The new structure takes advantage of the traditional hybrid mechanism architecture, but utilizes rigid mechanisms to couple the motions between ith link and i + 1th link rather than using cable actuation. By doing so, the overall tail becomes a rigid mechanism which achieves quasi-uniform spatial bending for each segment and allows performing highly dynamic motions. The mechanism and detailed design for this new tail are synthesized. The kinematic model was developed and an optimization process was conducted to minimize the bending non-uniformity for the rigid tail.

Design, Analysis, and Integration of a New Two-Degree-of-Freedom Articulated Multi-Link Robotic Tail Mechanism

2020 ◽  
Vol 12 (2) ◽  
Author(s):  
Yujiong Liu ◽  
Pinhas Ben-Tzvi
Keyword(s):  
Optimization Design ◽  
Kinematic Model ◽  
Low Frequency ◽  
Small Scale ◽  
Transmission Design ◽  
Redundant Design ◽  
Hybrid Mechanism ◽  
Single Link ◽  
Inertial Loading ◽  
Two Degree Of Freedom

Abstract Based on observations from nature, tails are believed to help animals achieve highly agile motions. Traditional single-link robotic tails serve as a good simplification for both modeling and implementation purposes. However, this approach cannot explain the complicated tail behaviors exhibited in nature where multi-link structures are more commonly observed. Unlike its single-link counterpart, articulated multi-link tails essentially belong to the serial manipulator family which possesses special motion transmission design challenges. To address this challenge, a cable-driven hyper-redundant design becomes the most used approach. Limited by cable strength and elastic components, this approach suffers from low-frequency response, inadequate generated inertial loading, and fragile hardware, which are all critical drawbacks for robotic tails design. To solve these structure-related shortcomings, a multi-link robotic tail made up of rigid links is proposed in this paper. The new structure takes advantage of the traditional hybrid mechanism architecture, but utilizes rigid mechanisms to couple the motions between the ith link and the (i + 1)th link rather than using cable actuation. By doing so, the overall tail becomes a rigid mechanism that achieves quasi-uniform spatial bending for each segment and allows performing highly dynamic motions. The mechanism and detailed design of this new robotic tail are presented. The kinematic model was developed and an optimization process was conducted to reduce the bending non-uniformity for the rigid tail. Based on this special optimization design, the dynamic model of the new mechanism is significantly simplified. A small-scale three-segment prototype was integrated to verify the proposed mechanism's unique mobility.

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Test System ◽  
Output Frequency ◽  
Frequency Effects ◽  
Adult Men ◽  
Frequency Responses ◽  
Significant Difference ◽  
Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

Prediction of Surge Motion Response of Floating Structure Using Kalman Smoother Adaptive Filters Based Time-Domain Volterra Model

2014 ◽  
Vol 660 ◽  
pp. 799-803
Author(s):  
Edwar Yazid ◽  
M.S. Liew ◽  
Setyamartana Parman ◽  
V.J. Kurian ◽  
C.Y. Ng
Keyword(s):  
Time Series ◽  
Transfer Function ◽  
Time Domain ◽  
Adaptive Filters ◽  
Low Frequency ◽  
Volterra Model ◽  
Floating Structure ◽  
Frequency Responses ◽  
Kalman Smoother ◽  
System Output

This work presents an approachto predict the low frequency and wave frequency responses (LFR and WFR) of afloating structure using Kalman smoother adaptive filters based time domain Volterramodel. This method utilized time series of a measured wave height as systeminput and surge motion as system output and used to generate the linear andnonlinear transfer function (TFs). Based on those TFs, predictions of surgemotion in terms of LFR and WFR were carried out in certain frequency ranges ofwave heights. The applicability of the proposed method is then applied in ascaled 1:100 model of a semisubmersible prototype.

On vibration isolation of sandwich plate with periodic hollow tube core

2017 ◽  
Vol 21 (3) ◽  
pp. 1119-1132 ◽  
Author(s):  
Gui-Lan Yu ◽  
Hong-Wei Miao
Keyword(s):  
Vibration Isolation ◽  
Sandwich Plate ◽  
Experimental Studies ◽  
Low Frequency ◽  
Dispersion Relations ◽  
Frequency Responses ◽  
Vibration Attenuation ◽  
Potential Applications ◽  
Vibration Isolation Performance ◽  
Isolation Performance

The vibration isolation performance of a PC sandwich plate with periodic hollow tube core is investigated experimentally and numerically. The experiment results reveal that there exist vibration attenuation zones in acceleration frequency responses which can be improved by increasing the number of periods or tuning some structure parameters. The presence of soft fillers shifts the attenuation zone to lower frequencies and enhances the capability of vibration isolation to some extent. Dispersion relations and acceleration frequency responses are calculated by finite element method using COMSOL MULTIPHYSICS. The attenuation zones obtained by experiments fit well with that by simulations, and both are consistent with the band gap in dispersion relations. The numerical and experimental studies in the present paper show that this PC sandwich plate exhibits a good performance on vibration isolation in low frequency ranges, which will provide some useful references for relevant research and potential applications in vibration propagation manipulations.

scholarly journals Resonator properties of paranasal sinuses: preliminary results of an anatomical study

2014 ◽  
Vol 52 (2) ◽  
pp. 178-182
Author(s):  
M. Havel ◽  
L. Ertl ◽  
D. Bauer ◽  
M. Schuster ◽  
K. Stelter ◽  
...  
Keyword(s):  
Paranasal Sinuses ◽  
Vocal Tract ◽  
Low Frequency ◽  
Anatomical Study ◽  
Sinus Surgery ◽  
Direct Access ◽  
Middle Meatus ◽  
Frequency Responses ◽  
Direct Exposure ◽  
Sine Tone

Background: The contribution of the nasal and paranasal cavities to vocal tract resonator properties is unclear as are voice effects of sinus surgery. Here we investigate resonance phenomena of paranasal sinuses with and without selective occlusion of the middle meatus and maxillary ostium in a cadaver. Methodology: Nasal and paranasal cavities of a Thiel-embalmed cadaver were excited by sine-tone sweeps from an earphone in the epipharynx. The response was picked up by a microphone at the nostrils. Different conditions with blocked and unblocked middle meatus were tested. Additionally, infundibulotomy was performed allowing direct access to and selective occlusion of the maxillary ostium. Results: Responses showed high reproducibility. Minor effects appeared after removal of meatal occlusion. A marked low frequency dip was detected after removal of occlusion of maxillary ostium following infundibulotomy. Conclusion: Reproducible frequency responses of nasal tract can be derived from cadaver measurements. Marked acoustic effects of the maxillary sinus appeared only after direct exposure of the maxillary ostium following infundibulotomy.

Evaluation of CFRP Hole Quality in Low Frequency Vibration-Assisted Dry Drilling of CFRP/Ti Stacks

2018 ◽  
Author(s):  
Haojun Yang ◽  
Yan Chen ◽  
Jiuhua Xu
Keyword(s):  
Feed Rate ◽  
Kinematic Model ◽  
Mechanical Damage ◽  
Low Frequency ◽  
Spindle Speed ◽  
Hole Quality ◽  
Drilling Force ◽  
Low Frequency Vibration ◽  
The Impact ◽  
Conventional Drilling

Low frequency vibration assisted drilling (LFVAD) is regarded as one of the most promising process in CFRP/Ti stacks drilling. This work carries the investigation of the difference between conventional drilling and LFVAD based on kinematic model. The experiments are conducted under varied vibration amplitude to a specific feed rate, also under varying spindle speeds, feed rates when the ratio of amplitude to feed rate is fixed. Then the hole quality of CFRP is evaluated based on the analysis of drilling force, chip morphology, chip extraction. The results show that there is rarely no difference between conventional drilling and LFVAD in drilling mechanism when the drilling diameter is over 1 mm. Because the impact effect caused by drill vibration is already weak. It is found that the severe mechanical damage of the CFRP holes surface could be significantly reduced due to the fragmented chips obtained in vibration drilling. The maximum instantaneous feed rate combined with feed rate and amplitude plays a significant role in CFRP hole quality. Lower maximum instantaneous feed rate results in better hole wall quality and less entry delamination. Spindle speed has no visible influence on entry delamination, while higher spindle speed improves the hole surface quality due to the resin coating phenomenon.

A New Extensible Continuum Manipulator Using Flexible Parallel Mechanism and Rigid Motion Transmission

2021 ◽  
pp. 1-23
Author(s):  
Yujiong Liu ◽  
Pinhas Ben-Tzvi
Keyword(s):  
Parallel Mechanism ◽  
Kinematic Model ◽  
Rigid Motion ◽  
Artificial Muscle ◽  
Dexterous Manipulation ◽  
Base Extension ◽  
Hybrid Mechanism ◽  
Continuum Robot ◽  
Kinematic Analyses ◽  
Continuum Manipulator

Abstract An extensible continuum manipulator (ECM) has specific advantages over its non-extensible counterparts. For instance, in certain applications, such as minimally invasive surgery or pipe inspection, the base motion might be limited or disallowed. The additional extensibility provides the robot with more dexterous manipulation and a larger workspace. Existing continuum robot designs achieve extensibility mainly through artificial muscle/pneumatic, extensible backbone, concentric tube, and base extension, etc. This paper proposes a new way to achieve this additional motion degree of freedom by taking advantage of the rigid coupling hybrid mechanism concept and a flexible parallel mechanism. More specifically, a rack and pinion set is used to transmit the motion of the i-th subsegment to drive the (i+1)-th subsegment. A six-chain flexible parallel mechanism is used to generate the desired spatial bending and one extension mobility for each subsegment. This way, the new manipulator can achieve tail-like spatial bending and worm-like extension at the same time. Simplified kinematic analyses are conducted to estimate the workspace and the motion non-uniformity. A proof-of-concept prototype was integrated to verify the mechanism’s mobility and to evaluate the kinematic model accuracy. The results show that the proposed mechanism achieved the desired mobilities with a maximum extension ratio of 32.2% and a maximum bending angle of 80 degrees.

Evaluation of Hardwire Personal Assistive Listening Devices

1994 ◽  
Vol 3 (2) ◽  
pp. 71-77 ◽  
Author(s):  
James J. Dempsey ◽  
Mark Ross
Keyword(s):  
Hearing Loss ◽  
Sensorineural Hearing Loss ◽  
Hearing Aids ◽  
Hearing Aid ◽  
Low Frequency ◽  
Sensorineural Hearing ◽  
Clinical Implications ◽  
Frequency Responses ◽  
Subjective Evaluations ◽  
Potential Benefits

A large number of personal amplifiers have recently become available commercially. These devices have not been classified as hearing aids by the FDA and are therefore not subject to the FDA rules and regulations governing the sales of hearing aid devices. In this investigation, several of these personal amplifiers were evaluated to determine potential benefits and problems for each device. The devices were evaluated electroacoustically and, also, subjectively by a group of adults with sensorineural hearing loss. The results of the electroacoustic evaluation revealed very sharply peaked frequency responses. The subjective evaluations revealed tremendous variability, with some preferences for power and low-frequency amplification. Clinical implications of these results and suggestions for further research are provided.

Effects of endogenous and exogenous prostaglandin in neurotransmission in canine trachea

1987 ◽  
Vol 65 (7) ◽  
pp. 1433-1441 ◽  
Author(s):  
E. E. Daniel ◽  
C. Davis ◽  
V. Sharma
Keyword(s):  
Nerve Stimulation ◽  
Potent Inhibitor ◽  
Dose Range ◽  
Low Frequency ◽  
Organ Bath ◽  
Field Stimulation ◽  
Frequency Responses ◽  
Amplitude Maximum ◽  
Excitatory Junction Potentials ◽  
Sucrose Gap

The effect of PGE2 on neurotransmission in the canine tracheal strip dissected free of epithelium was studied in the single sucrose gap and organ bath. PGE2 was a potent inhibitor of the initiation of excitatory junction potentials (ejps) by just submaximal nerve stimulation. In a concentration of 10−9 or 10−8 M PGE2 nearly or completely abolished them. Contractile responses to field stimulation in the sucrose gap at 27 °C or in muscle baths at 37 °C were also reduced or abolished by PGE2 in the same dose range; reductions were greater at low frequency. Responses to acetylcholine were also depressed but significantly less than to field stimulation. These are consistent with major presynaptic as well as some postsynaptic inhibitory actions of PGE2. No evidence was obtained that endogenous PGE2 affected excitatory junction potentials and contractions; i.e. they were stable for hours and unaffected by indomethacin 10−6 and 10−5 M under our conditions. Post-stimulus potentiation of ejps amplitude, maximum at 10 s, was observed and became more marked after the first ejp had been markedly reduced or abolished by PGE2. This potentiation was unaffected by indomethacin. It was suggested that a presynaptic process inhibited by PGE2 might participate in this potentiation. The canine trachea is a useful preparation when studied under the experimental condition used here for study of effects of products of arachidonate on neurotransmission.

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