scholarly journals Haptic Identification of Surfaces as Fields of Force

2006 ◽  
Vol 95 (2) ◽  
pp. 1068-1077 ◽  
Author(s):  
Vikram S. Chib ◽  
James L. Patton ◽  
Kevin M. Lynch ◽  
Ferdinando A. Mussa-Ivaldi
Keyword(s):  
Mechanical Properties ◽  
Hand Movement ◽  
Sensory Information ◽  
Internal Representation ◽  
Interaction Force ◽  
Adaptive Responses ◽  
Object Boundary ◽  
Average Force ◽  
Interaction Forces ◽  
First Case

The ability to discriminate an object's shape and mechanical properties from touch is one of the most fundamental somatosensory functions. When exploring physical properties of an object, such as stiffness and curvature, humans probe the object's surface and obtain information from the many sensory receptors in their upper limbs. This sensory information is critical for the guidance of actions. We studied how humans acquire an internal representation of the shape and mechanical properties of surfaces and how this information affects the execution of trajectories over the surface. Experiments involved subjects executing trajectories while holding a planar manipulandum that renders planar virtual objects with variable shape and mechanical properties. Subjects were instructed to make reaching movements with the hand between points on the boundary of a curved virtual disk of varying stiffness and curvature. The results suggest two classifications of adaptive responses: force perturbations and object boundaries. In the first case, a rectilinear hand movement is enforced by opposing the interaction forces. In the second case, the trajectory conforms to the object boundary so as to reduce interaction forces. While this dichotomy is evident for very rigid and very soft objects, the likelihood of an object boundary classification depended, in a smooth and monotonic way, on the average force experienced during the initial movements. Furthermore, the observed response across a variety of stiffness values lead to a constant average interaction force after adaptation. This suggests that the nervous system may select from the two responses through a mechanism that attempts to establish a constant interaction force.

Case Report: Management of a Patient with mTBI and Vestibular Hypofunction with the Binasal Occlusion Technique

2018 ◽  
pp. 87-90
Keyword(s):  
Case Report ◽  
Visual Motion ◽  
Hand Movement ◽  
Motion Sensitivity ◽  
Vestibular Hypofunction ◽  
First Case ◽  
Neurological Exam ◽  
History Of ◽  
Occlusion Technique ◽  
Visual Vertigo

Background: Binasal Occlusion (BNO) is a clinical technique used by many neurorehabilitative optometrists in patients with mild traumatic brain injury (mTBI) and increased visual motion sensitivity (VMS) or visual vertigo. BNO is a technique in which partial occluders are added to the spectacle lenses to suppress the abnormal peripheral visual motion information. This technique helps in reducing VMS symptoms (i.e., nausea, dizziness, balance difficulty, visual confusion). Case Report: A 44-year-old AA female presented for a routine eye exam with a history of mTBI approximately 33 years ago. She was suffering from severe dizziness for the last two years that was adversely impacting her ADLs. The dizziness occurred in all body positions and all environments throughout the day. She was diagnosed with vestibular hypofunction and had undergone vestibular therapy but reported little improvement. Neurological exam revealed dizziness with both OKN drum and hand movement, especially in the left visual field. BNO technique resulted in immediate relief of her dizziness symptoms. Conclusion: To our knowledge, this is the first case that illustrates how the BNO technique in isolation can be beneficial for patients with mTBI and vestibular hypofunction. It demonstrates the success that BNO has in filtering abnormal peripheral visual motion in these patients.

scholarly journals Perceptual attraction in tool use: evidence for a reliability-based weighting mechanism

2017 ◽  
Vol 117 (4) ◽  
pp. 1569-1580 ◽  
Author(s):  
Nienke B. Debats ◽  
Marc O. Ernst ◽  
Herbert Heuer
Keyword(s):  
Multisensory Integration ◽  
Tool Use ◽  
Reference Frames ◽  
Hand Movement ◽  
Sensory Information ◽  
Integration Model ◽  
Distant Object ◽  
Relative Reliability ◽  
Weighting Mechanism ◽  
Kinematic Transformation

Humans are well able to operate tools whereby their hand movement is linked, via a kinematic transformation, to a spatially distant object moving in a separate plane of motion. An everyday example is controlling a cursor on a computer monitor. Despite these separate reference frames, the perceived positions of the hand and the object were found to be biased toward each other. We propose that this perceptual attraction is based on the principles by which the brain integrates redundant sensory information of single objects or events, known as optimal multisensory integration. That is, 1) sensory information about the hand and the tool are weighted according to their relative reliability (i.e., inverse variances), and 2) the unisensory reliabilities sum up in the integrated estimate. We assessed whether perceptual attraction is consistent with optimal multisensory integration model predictions. We used a cursor-control tool-use task in which we manipulated the relative reliability of the unisensory hand and cursor position estimates. The perceptual biases shifted according to these relative reliabilities, with an additional bias due to contextual factors that were present in experiment 1 but not in experiment 2. The biased position judgments’ variances were, however, systematically larger than the predicted optimal variances. Our findings suggest that the perceptual attraction in tool use results from a reliability-based weighting mechanism similar to optimal multisensory integration, but that certain boundary conditions for optimality might not be satisfied. NEW & NOTEWORTHY Kinematic tool use is associated with a perceptual attraction between the spatially separated hand and the effective part of the tool. We provide a formal account for this phenomenon, thereby showing that the process behind it is similar to optimal integration of sensory information relating to single objects.

The interaction of a rising bubble and a particle in oscillating fluid

2016 ◽  
Vol 807 ◽  
pp. 205-220 ◽  
Author(s):  
D. V. Lyubimov ◽  
L. S. Klimenko ◽  
T. P. Lyubimova ◽  
L. O. Filippov
Keyword(s):  
Fine Particle ◽  
Considerable Increase ◽  
Effective Cross Section ◽  
Interaction Force ◽  
Average Force ◽  
Flotation Process ◽  
Rising Bubble ◽  
Buoyancy Forces ◽  
Bubble Oscillations ◽  
Ultrasound Action

This article considers the interaction of a rising bubble and a sedimenting fine particle in an incompressible viscous liquid under vibrations (ultrasound). The particle is subject to Stokes, Basset and buoyancy forces, and average force due to the inhomogeneity of the pulsating field. It is shown that the main contribution to the average force is made by interference of the external field and the field caused by the monopole mode of bubble oscillations. The interaction force is the attraction of the particle to the bubble. It is found that even weak vibrations lead to considerable increase of the effective cross-section of particle capture by the bubble. The evaluation of the efficiency of the flotation process exposed to an ultrasound action is discussed.

Mechanical System Modelling Using Physics-Based and Data-Based Subsystems

2020 ◽  
Author(s):  
Siamak Arbatani ◽  
József Kövecses
Keyword(s):  
Mechanical System ◽  
Interaction Force ◽  
Point Of View ◽  
Training Data ◽  
System Modelling ◽  
Core Element ◽  
Interaction Forces ◽  
Force Systems ◽  
Using Data ◽  
Novel Concept

Abstract Mechanical systems have been traditionally represented using parametric physics-based models. In this work, we introduce a novel concept, in this part of the mechanical system is represented using data-based subsystem models, and the overall mechanical system model is composed of these data-based and other, physics-based subsystems. A core element is the interfacing of the subsystems, which gives rise to interaction forces. The interfacing problem is formulated in a way that makes it possible to give a general representation to the interaction forces. We demonstrate that from the point of view of the physics-based subsystems the important element is that the data-based models can represent the interaction force systems properly. The data-based subsystems are developed using deep recurrent neural networks, and the training data is generated based on simulations using the fully parametric physics-based model of the system. Such training data could also be obtained through physical experimentation.

Numerical Study on Electrokinetic Interaction Between a Pair of Cylindrical Colloidal Particles

2009 ◽  
Author(s):  
Dolfred Vijay Fernandes ◽  
Sangmo Kang ◽  
Yong Kweon Suh
Keyword(s):  
Flow Field ◽  
Electric Field ◽  
Colloidal Particles ◽  
Stokes Equations ◽  
Separation Efficiency ◽  
Numerical Study ◽  
Interaction Force ◽  
Surface Element ◽  
Immersed Boundary ◽  
Interaction Forces

Electrophoresis is the motion of dispersed particles relative to a fluid under the influence of an electric field. Presently this phenomenon of electrokinetics is widely used in biotechnology for the separation of proteins, sequencing of polypeptide chains etc. The separation efficiency of these biomolecules is affected by their aggregation. Thus it is important to study the interaction forces between the molecules. In this study we calculate the electrophoretic motion of a pair of colloidal particles under axial electric field. The hydrodynamic and electric double layer (EDL) interaction forces are calculated numerically. The EDL interaction force is calculated from electric field distribution around the particle using Maxwell stress tensor and the hydrodynamic force is calculated from the flow field obtained from the solution of Stokes equations. The continuous forcing approach of immersed boundary method is used to obtain flow field around the moving particles. The EDL distribution around the particles is obtained by solving Poisson-Nernst-Planck (PNP) equations on a hybrid grid system. The EDL interaction force calculated from numerical solution is compared with the one obtained from surface element integration (SEI) method.

scholarly journals Translation of a Coated Rigid Spherical Inclusion in an Elastic Matrix: Exact Solution, and Implications for Mechanobiology

2019 ◽  
Vol 86 (5) ◽  
Author(s):  
Xin Chen ◽  
Moxiao Li ◽  
Shaobao Liu ◽  
Fusheng Liu ◽  
Guy M. Genin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Exact Solution ◽  
Analytical Solution ◽  
Spherical Inclusion ◽  
Matrix Material ◽  
Elastic Matrix ◽  
Protein Ligands ◽  
First Case ◽  
The Matrix ◽  
Matrix Modulus

The displacement of relatively rigid beads within a relatively compliant, elastic matrix can be used to measure the mechanical properties of the matrix. For example, in mechanobiological studies, magnetic or reflective beads can be displaced with a known external force to estimate the matrix modulus. Although such beads are generally rigid compared to the matrix, the material surrounding the beads typically differs from the matrix in one or two ways. The first case, as is common in mechanobiological experimentation, is the situation in which the bead must be coated with materials such as protein ligands that enable adhesion to the matrix. These layers typically differ in stiffness relative to the matrix material. The second case, common for uncoated beads, is the situation in which the beads disrupt the structure of the hydrogel or polymer, leading to a region of enhanced or reduced stiffness in the neighborhood of the bead. To address both cases, we developed the first analytical solution of the problem of translation of a coated, rigid spherical inclusion displaced within an isotropic elastic matrix by a remotely applied force. The solution is applicable to cases of arbitrary coating stiffness and size of the coating. We conclude by discussing applications of the solution to mechanobiology.

MUSCULOSKELETAL STABILIZATION OF THE ELBOW — COMPLEX OR REAL

2007 ◽  
Vol 07 (03) ◽  
pp. 275-296 ◽  
Author(s):  
HEIKO WAGNER ◽  
PETER GIESL ◽  
REINHARD BLICKHAN
Keyword(s):  
Mechanical Properties ◽  
Musculoskeletal System ◽  
Sensory Information ◽  
Arm Movements ◽  
Biomechanical Model ◽  
Environmental Perturbations ◽  
Complex Eigenvalues ◽  
Study Support ◽  
The Stability ◽  
Musculoskeletal Systems

Both sensory information and mechanical properties of the musculoskeletal system are necessary for fast and appropriate reactions of humans and animals to environmental perturbations. In this paper, we focus on the musculoskeletal system and study the stability of a human elbow in an equilibrium state. We derive a biomechanical model of the human elbow, including an antagonistic pair of muscles, and investigate the stability analytically based on the theory of Ljapunov. Depending on the elbow angle and the level of coactivation, we obtain the following three qualitatively different behaviors: unstable, stable with real eigenvalues, and stable with complex eigenvalues. If the eigenvalues are real, then the system is critically damped; for complex eigenvalues, solutions near the equilibrium are oscillating. Based on experimental data, we found that in principle real and complex behaviors may occur in human arm movements. The experiments support the analytical predictions. Furthermore, in agreement with the simulations, we found differences in the experimental results among the subjects. The results of this study support the assumption that arm movements around an equilibrium point may be self-stabilized without sensory feedback or motor control, based only on mechanical properties of musculoskeletal systems.

scholarly journals How chimpanzees integrate sensory information to select figs

2016 ◽  
Vol 6 (3) ◽  
pp. 20160001 ◽  
Author(s):  
Nathaniel J. Dominy ◽  
Justin D. Yeakel ◽  
Uttam Bhat ◽  
Lawrence Ramsden ◽  
Richard W. Wrangham ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Colour Vision ◽  
Sensory Information ◽  
Primate Evolution ◽  
Visuomotor Control ◽  
Quality Information ◽  
Specific Information ◽  
Sensory Cues ◽  
Selective Force ◽  
Domain Specific

Figs are keystone resources that sustain chimpanzees when preferred fruits are scarce. Many figs retain a green(ish) colour throughout development, a pattern that causes chimpanzees to evaluate edibility on the basis of achromatic accessory cues. Such behaviour is conspicuous because it entails a succession of discrete sensory assessments, including the deliberate palpation of individual figs, a task that requires advanced visuomotor control. These actions are strongly suggestive of domain-specific information processing and decision-making, and they call attention to a potential selective force on the origin of advanced manual prehension and digital dexterity during primate evolution. To explore this concept, we report on the foraging behaviours of chimpanzees and the spectral, chemical and mechanical properties of figs, with cutting tests revealing ease of fracture in the mouth. By integrating the ability of different sensory cues to predict fructose content in a Bayesian updating framework, we quantified the amount of information gained when a chimpanzee successively observes, palpates and bites the green figs of Ficus sansibarica . We found that the cue eliciting ingestion was not colour or size, but fig mechanics (including toughness estimates from wedge tests), which relays higher-quality information on fructose concentrations than colour vision. This result explains why chimpanzees evaluate green figs by palpation and dental incision, actions that could explain the adaptive origins of advanced manual prehension.

Interaction Force Between Thin Film Disk Media and Elastic Solids Investigated by Atomic Force Microscope

1990 ◽  
Vol 112 (3) ◽  
pp. 567-572 ◽  
Author(s):  
T. Miyamoto ◽  
R. Kaneko ◽  
Y. Ando
Keyword(s):  
Thin Film ◽  
Single Crystal ◽  
Single Crystal Silicon ◽  
Static Friction ◽  
Interaction Force ◽  
Elastic Solids ◽  
Crystal Silicon ◽  
Interaction Forces ◽  
Liquid Lubricant ◽  
Atomic Force

Atomic force microscopy is used to investigate the interaction force between the sharp tips of various elastic solids and four different samples. The samples are: thin film disk media coated with functional liquid lubricant having diol end groups, unlubricated disk media, a single-crystal silicon wafer, and Au evaporated onto single-crystal silicon. Relationships between the interaction and static friction force of disk media and a taper flat type head slider are examined. The interaction force between a disk medium coated with a functional liquid lubricant greater than 11.0 nm thick and tungsten tips with radii of 5 μm-100 μm is caused by the functional liquid lubricant meniscus, as pointed out by McFarlane and Tabor. However, at a thickness of several nanometers, the interaction force has a lower value than that for lubricant thicknesses above 11.0 nm. The interaction force has a minimum value of 0.4 μN at the functional liquid lubricant thickness of 2.0 nm. Mean interaction forces of the tungsten, Al2O3 − TiC and Si3N4 tips on a disk medium coated with a 2.0-nm-thick functional liquid lubricant are less than 0.1 times those for an unlubricated disk medium. Interaction forces of the SiC tip show very low values, even when the disk medium is unlubricated. Static friction force between a thin-film disk medium and a head or sphere is dependent on the interaction force between the medium and a tip that is made of the same material as the head or sphere. The use of an atomic force microscope (AFM), may allow the surface structure to be more thoroughly analyzed.

scholarly journals Toward an Integrated Intervention and Assessment of Robot-Based Rehabilitation

2020 ◽  
Vol 3 (2) ◽  
Author(s):  
Amirhossein Majidirad ◽  
Yimesker Yihun ◽  
Laila Cure
Keyword(s):  
Force Sensor ◽  
Interaction Force ◽  
Human Robot Interaction ◽  
Feature Reduction ◽  
Physiological Data ◽  
Training Procedure ◽  
Interaction Forces ◽  
Response Data ◽  
Robotic Devices ◽  
Research Challenge

Abstract This study presents robot-based rehabilitation and its assessment. Robotic devices have significantly been useful to help therapists do the training procedure consistently. However, as robotic devices interface with humans, quantifying the interaction and its intended outcomes is still a research challenge. In this study, human–robot interaction during rehabilitation is assessed based on measurable interaction forces and human physiological response data, and correlations are established to plan the intervention and effective limb trajectories within the intended rehabilitation and interaction forces. In this study, the Universal Robot 5 (UR5) is used to guide and support the arm of a subject over a predefined trajectory while recording muscle activities through surface electromyography (sEMG) signals using the Trigno wireless DELSYS devices. The interaction force is measured through the force sensor mounted on the robot end-effector. The force signals and the human physiological data are analyzed and classified to infer the related progress. Feature reduction and selection techniques are used to identify redundant inputs and outputs.

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