Objects Of Different Mass Research Articles

Bimodal Intelligent Electronic Skin Based on Proximity and Tactile Interaction for Pressure and Configuration Perception.

The flexible bimodal e-skin exhibits significant promise for integration into the next iteration of human-computer interactions, owing to the integration of tactile and proximity perception. However, those challenges, such as low tactile sensitivity, complex fabrication processes, and incompatibility with bimodal interactions, have restricted the widespread adoption of bimodal e-skin. Herein, a bimodal capacitive e-skin capable of simultaneous tactile and proximity sensing has been developed. The entire process eliminates intricate fabrication techniques, employing DLP-3D printing for the electrode layers and sacrificial templating for the dielectric layers, conferring high tactile sensitivity (1.672 kPa-1) and rapid response capability (∼30 ms) to the bimodal e-skin. Moreover, exploiting the "fringing electric field" effect inherent in parallel-plate capacitors has facilitated touchless sensing, thereby enabling static distance recognition and dynamic gesture recognition of varying materials. Interestingly, an e-skin sensing array was created to identify the positions and pressure levels of various objects of different masses. Furthermore, with the aid of machine learning techniques, an artificial neural network has been established to possess intelligent object recognition capabilities, facilitating the identification, classification, and training of various object configurations. The advantages of the bimodal e-skin render it highly promising for extensive applications in the field of next-generation human-machine interaction.

The (Un)ideal Physicist: How Humans Rely on Object Interaction for Friction Estimates.

To estimate object properties such as mass or friction, our brain relies on visual information to efficiently compute approximations. The role of sensorimotor feedback, however, is not well understood. Here we tested healthy adults (N = 79) in an inclined-plane problem, that is, how much a plane can be tilted before an object starts to slide, and contrasted the interaction group with observation groups who accessed involved forces by watching objects being manipulated. We created objects of different masses and levels of friction and asked participants to estimate the critical tilt angle after pushing an object, lifting it, or both. Estimates correlated with applied forces and were biased toward object mass, with higher estimates for heavier objects. Our findings highlight that inferences about physical object properties are tightly linked to the human sensorimotor system and that humans integrate sensorimotor information even at the risk of nonveridical perceptual estimates.

Sandpaper-assisted preparation of microstructured multifunctional PANI/PVA composite hydrogel film for high-sensitivity pressure sensors with accurate pressure identification and motion monitoring

Bio-inspired microstructure surface flexible piezoresistive sensors offer an attractive opportunity for a variety of wearable device applications. Unfortunately, the realization of high-performance piezoresistive sensors still faces great challenges owing to the balance between responsitivity and sensing capability of them, as well as being limited by the level of deformation of their surface structures. Here, we propose a simple and efficient, low-cost sandpaper-assisted solution casting-scraping strategy to fabricate PANI/PVA hydrogel film with the reverse random height distribution (RHD) spinosum microstructure on the surface that is simultaneously conductive, flame retardant, and EMI shielding. The flexible piezoresistive sensor designed based on this film can detect pressure from 0.01 N to 20 N with a responsitivity of 77.7263 kPa−1 in the region of 0.03183–1.27324 kPa, a quick response/recovery delay of 18 ms/30 ms, and a good reliability within 2000 load-unload cycles. Notably, this piezoresistive sensor can accurately identify objects of different masses and monitor physiological signals of human motion, and can also produce significant current responses to extremely slight mouse clicks and handwriting styles. The successful preparation of multifunctional PANI/PVA microstructured film provides a new idea to explore the potential applications of piezoresistive sensors in flexible wearable electronic devices.

A High-Speed Test of the Equivalence Principle

It is well known that Newton’s work on mechanics depended in a crucial way on the previous observations of Galileo. The key insight of Galileo was that one can analyze the motion of bodies using experiments and mathematical equations. One experimental observation that roughly emerges from this work in modern terms is that two objects of different mass that are simultaneously released from rest and allowed to fall under the influence of gravity through a vacuum should hit the ground at the same time (this is essentially what is called the equivalence principle in general relativity). In popular legend, it is said that Galileo tested this by dropping two balls of different masses from the Leaning Tower of Pisa and showing that they hit the ground at the same time, but the historical evidence suggests that this is unlikely as he seems to have experimented mostly with balls rolling down inclined slopes.

Constraint-based Simulation of Passive Suction Cups

In this paper, we propose a physics-based model of suction phenomenon to achieve simulation of deformable objects like suction cups. Our model uses a constraint-based formulation to simulate the variations of pressure inside suction cups. The respective internal pressures are represented as pressure constraints which are coupled with anti-interpenetration and friction constraints. Furthermore, our method is able to detect multiple air cavities using information from collision detection. We solve the pressure constraints based on the ideal gas law while considering several cavity states. We test our model with a number of scenarios reflecting a variety of uses, for instance, a spring loaded jumping toy, a manipulator performing a pick and place task, and an octopus tentacle grasping a soda can. We also evaluate the ability of our model to reproduce the physics of suction cups of varying shapes, lifting objects of different masses, and sliding on a slippery surface. The results show promise for various applications such as the simulation in soft robotics and computer animation.

Modeling and analysis of nature-inspired branched micropillars for enhanced dynamic bio-sensing.

Research evidence abounds on the effectiveness of micropillar-based microelectromechanical systems for the detection of a wide variety of ultrasmall biological objects for clinical and non-clinical applications. However, the standard micropillar-based sensing platforms rely on a single-column micropillar with a spot at the tip for binding of objects. Although this long-standing form has shown immense potential, performance improvement is hindered by the fundamental limits enforced by physical laws. Moreover, the single-column micropillar has a lower sensing area and is ill-suited for a simultaneous differential sensing of chemical/biological objects of different mass. Here, we report a new set of nature-inspired, branched micropillar-based sensing resonators to address the highlighted issues. The characteristics of the newly proposed branched micropillars are comprehensively examined with three payloads (Bartonella Bacilliformis, Escherichia coli, and Micro magnetic beads). Anchored on the capability of continuum theoretical framework, the mathematical model of the micropillar is formulated through the synthesis of the modified couple stress, the Rayleigh-Love, and the Timoshenko theories. The finite element method is employed to shed light on the variability of the structures' resonant response under performance reduction factors (payload's rotary inertia, damaged substrate, and density of a surrounding fluid). The results obtained indicate superior performance indicators for the triply-branched micropillar: enhanced response sensitivity for multiple payloads and less susceptibility to deterioration in resonant frequencies due to fluid immersion.

Dynamics of a Spool-Block Atwood System

For many years, Atwood’s machine has been used to demonstrate, illustrate, or verify Newton’s laws in introductory physics courses. It consists of two objects of different mass that are fastened to the ends of a string that hangs over a pulley. In an idealized situation, one assumes that pulley friction, the string’s mass, and changes in the string’s length are negligible. Cases in which the pulley’s mass is non-negligible may be considered. Advanced students can investigate non-ideal cases in which the string’s mass or friction is not negligible or cases in which the masses swing. Computer-based data acquisition tools allow quick and accurate measurements of the acceleration of the objects in the Atwood machine. They enable an instructor to ask probing questions regarding this apparatus while quickly verifying its prevailing physical principles through simple measurements. Two interesting questions that one can ask are: Question (1): “What is the acceleration of the objects in an Atwood machine when both objects are of equal mass with one being an unraveling spool?”Question (2): “Is it possible to determine a mass ratio in which the acceleration of the spool is non-zero while the acceleration of the other object is zero?”

A soft continuum robot, with a large variable-stiffness range, based on jamming

Inspired by the physiological structure of the hand capable of realizing the continuous change in finger stiffness when grasping objects of different masses, a self-locking soft continuum robot with a large variable-stiffness range based on particle jamming and fibre jamming is proposed in this paper to meet the requirements of it in practical application. In this paper, a variable stiffness range is derived due to the good fluidity and rigidity of the spherical particles and the low elasticity and high toughness of the fibres. Then, an analysis model is established to deduce its self-locking condition, and the deflection angle of self-locking under the influence of external force is about 0.17 rad. The maximum stiffness of the experimental prototype can reach 1223.58 N m−1 due to the limitation of the experimental materials, despite the fact that the theoretical stiffness can be increased infinitely after self-locking. To explain the adaptability of the robot, the adaptive conditions of the soft continuum robot with variable stiffness are deduced. A new evaluation index, the adaptive intensity of the soft continuum robot, is introduced and the adaptability experiments are carried out. In adaptability experiments, the maximum bending angle of the continuum robot reaches 108°. Finally, the adaptability of the soft continuum robot to different geometries is discussed.

A quantum test of free fall

Physics![Figure][1] The Leaning Tower of Pisa, Italy PHOTO: © STEFANO POLITI MARKOVINA/ALAMY STOCK PHOTO Galileo Galilei is purported to have dropped objects of different mass from the Leaning Tower of Pisa to demonstrate that they fall at the same rate. In formulating his general theory of relativity, Einstein described this as the universality of free fall—that all objects, irrespective of their mass, will behave identically when subject to the same gravitational field. Taking this into the quantum regime, Duan et al. performed Galileo's drop experiment with rubidium atoms of different quantum mechanical spins. With a sensitive atom-interferometer setup, they showed that the atoms fall at the same rate to within one part in 10 million, upholding Einstein's universality proposition for now. While we await a theory that can unify relativity and the principles of quantum mechanics, such precision-based experimental tests should help place bounds on any proposed theories of quantum gravity. Phys. Rev. Lett. 117 , 023001 (2016). [1]: pending:yes

Pseudo force acting between bodies

It has been shown that a non-contact force acts between two macroscopic physical objects held close together, which is not associated with the gravitational and electrostatic force. An experiment was conducted with objects of different mass, material and geometry to find the magnitude and properties of this apparent or pseudo force. The order of magnitude was found to be 10−5 and it remained constant for all types of objects while only the coefficient increased as the distance between the objects reduced. It only started acting at small distances and failed to make a body move if it experienced static friction from any contact surface. The nature of the force was found to be attractive as well as repulsive. Due to gravitation being a solely attractive force, it was eliminated as a possible reason for the pseudo force. The experiment was performed twice, once by grounding the apparatus and then again without grounding. The order of the force remained the same for both cases. As the test objects were held by hand, they were grounded through the human body. Also, none of the objects used were in contact with each other for the duration of this work, preventing any contact electrification. Due to these factors, the force was not considered electrostatic in nature.

How substance-based ontologies for gravity can be productive: A case study

Many science education researchers have argued that learners’ commitment to a substance (matter-based) ontology impedes the learning of scientific concepts that scientists typically conceptualize as processes or interactions, such as force, electric current, and heat. By this account, students’ tendency to classify these entities as substances or properties of substances leads to robust misconceptions, and instruction should steer novices away from substance-based reasoning. We argue that substance-based reasoning can contribute to the learning and understanding of these very same physics concepts. Our case study focuses on a group of elementary school science teachers in our professional development program. Starting from substance-based metaphors for gravity, the teachers build a sophisticated explanation for why objects of different masses fall with the same acceleration. We argue that, for conceptual, epistemological, and affective reasons, instructional interventions should focus on tapping these productive substance-based resources when they arise rather than attempting to suppress them.Received 6 May 2013DOI:https://doi.org/10.1103/PhysRevSTPER.10.010113This article is available under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.Published by the American Physical Society

Center or side: biases in selecting grasp points on small bars

Choosing appropriate grasp points is necessary for successfully interacting with objects in our environment. We brought two possible determinants of grasp point selection into conflict: the attempt to grasp an object near its center of mass to minimize torque and ensure stability and the attempt to minimize movement distance. We let our participants grasp two elongated objects of different mass and surface friction that were approached from different distances to both sides of the object. Maximizing stability predicts grasp points close to the object's center, while minimizing movement costs predicts a bias of the grasp axis toward the side at which the movement started. We found smaller deviations from the center of mass for the smooth and heavy object, presumably because the larger torques and more slippery surface for the heavy object increase the chance of unwanted object rotation. However, our right-handed participants tended to grasp the objects to the right of the center of mass, irrespective of where the movement started. The rightward bias persisted when vision was removed once the hand was half way to the object. It was reduced when the required precision was increased. Starting the movement above the object eliminated the bias. Grasping with the left hand, participants tended to grasp the object to the left of its center. Thus, the selected grasp points seem to reflect a compromise between maximizing stability by grasping near the center of mass and grasping on the side of the acting hand, perhaps to increase visibility of the object.

Transforming a traditional hands-on activity into an enquiry activity to foster morein-depth understanding of the concept of density

Traditional methods used to teach the concept of density that employ solid objects ofdifferent masses and volumes can be supplemented by enquiry activities in which studentsvary the mass-to-volume ratio of the same object to test ideas about density andflotation. A simple substance, Blu-Tack, is an ideal material to use in this case.The activity introduced in this article not only allows students to explore theeffect of air on the density and flotation of an object, but also stimulates them torelate a macroscopic property such as density to the microscopic structure ofmatter.

Arbitrary visuomotor mapping during object manipulation in Parkinson's disease

The objective of this study is to investigate whether subjects with Parkinson's disease are able to use arbitrary color cues linked to the mass of an object to be lifted allowing for the predictive selection of appropriate grip forces. Fourteen patients with Parkinson's disease used a precision grip to lift two objects of different masses (400 and 600 g) in random order. In a "no cue" condition, a noninformative neutral visual stimulus was presented before each lift, thereby not allowing any judgement about which mass to be lifted. In a "cue" condition an arbitrary color cue provided advance information about which of the two masses patients would have to lift in the subsequent trial. Patients performed the conditions with either hand and by both on and off drugs. In the "no cue" trials patients scaled the predictive grip force output according to the perceived mass of the preceding lift. In the "cue" experiment patients scaled grip force in a predictive manner to mass based on the provided color cues. The ability of arbitrary visuomotor mapping was evident at either hand and not influenced by medication on/off. The precision of arbitrary visuomotor mapping correlated negatively with age, but not with disease duration, severity of motor disability on and off drug, severity of cognitive impairment on and off drug, or the amount of levodopa equivalent daily dosage of dopaminergic drugs. These data imply that Parkinson's disease does not preclude the ability of visuomotor mapping in the grip-lift task.

Photonic Guided-Path Tomography sensor for deformation in a non-planar surface

We introduce theoretically and demonstrate experimentally the performance of a Guided-Path Tomography sensor head and a complete system for imaging of physical parameters on non-planar and possibly flexible surfaces. Novel in our approach is to employ waveguiding sensor elements, strategically arranged on the imaged surface, to allow tomography measurements and the inverse problem solution. In the reported particular implementation we image deformation over ∼1sq.m., which is achieved by sensitizing the sensor elements to bending. The problem of severely limited number of measurements is addressed by an original method for sinogram recovery, followed by the application of well established methods for solving the hard-field tomography inverse problem. We show that the sensor is capable of distinguishing objects of different mass and shape of footprint. It also calculates the coordinates of the centre of mass of the imaged objects, which facilitates integration with control systems.

On the role of the ventral premotor cortex and anterior intraparietal area for predictive and reactive scaling of grip force

When lifting objects of different mass but identical visual appearance, we apply grip forces that match the expected mass of the object. Here we study the role of the primary motor cortex (M1), the ventral premotor cortex (PMv) and the anterior intraparietal area (AIP) for predictive and reactive scaling of grip forces. Participants performed a precision grip between the index finger and thumb of the right hand to lift two different masses of identical visual appearance in random order. Neuronavigated single pulse transcranial magnetic stimulation (TMS) over (i) left M1, (ii) left PMv, (iii) left AIP and (iv) the vertex (for control) was applied at two time points of the grasping movement after an unexpected change in mass had occurred: (a) at the time of movement onset and (b) at the time of peak grasp aperture. TMS over the PMv, but not over the vertex, M1 or the AIP, interfered with the predictive scaling of grip forces according to the most recent lift when applied at the time of peak grasp aperture. In contrast, TMS over AIP, but not over the vertex, M1 or PMv, disrupted the reactive adjustment of grip force to the novel mass of the object at hand. The findings highlight the differential involvement of PMv in the predictive scaling of grip force and of AIP in the reactive online adjustment of grip force during object manipulation.

Continuous theta-burst stimulation over the dorsal premotor cortex interferes with associative learning during object lifting

When lifting objects of different mass, humans scale grip force according to the expected mass. In this context, humans are able to associate a sensory cue, such as a colour, to a particular mass of an object and link this association to the grip forces necessary for lifting. Here, we study the role of the dorsal premotor cortex (PMd) in setting-up an association between a colour cue and a particular mass to be lifted. Healthy right-handed subjects used a precision grip between the index finger and thumb to lift two different masses. Colour cues provided information about which of the two masses subjects would have to lift. Subjects first performed a series of lifts with the right hand to establish a stable association between a colour cue and a mass, followed by 20 sec of continuous high frequency repetitive trancranial magnetic stimulation using a recently developed protocol (continuous theta-burst stimulation, cTBS) over (i) the left primary motor cortex, (ii) the left PMd and (iii) the left occipital cortex to be commenced by another series of lifts with either the right or left hand. cTBS over the PMd, but not over the primary motor cortex or O1, disrupted the predictive scaling of isometric finger forces based on colour cues, irrespective of whether the right or left hand performed the lifts after the stimulation. Our data highlight the role of the PMd to generalize and maintain associative memory processes relevant for predictive control of grip forces during object manipulation.

Using 1/f noise to examine planning and control in a discrete aiming task

The present study used 1/f noise to examine how spatial, physical, and timing constraints affect planning and control processes in aiming. Participants moved objects of different masses to different distances at preferred speed (Experiment 1) and as quickly as possible (Experiment 2). Power spectral density, standardized dispersion, rescaled range, and an autoregressive fractionally integrated moving average (ARFIMA) model selection procedure were used to quantify 1/f noise. Measures from all four analyses were in reasonable agreement, with more ARFIMA (long-range) models selected at peak velocity in Experiment 1 and fewer selected at peak velocity in Experiment 2. There also was a nonsignificant trend where, at preferred speed, of those participants who showed 1/f noise, more tended to show 1/f noise at peak velocity, when planning and control would overlap most. This trend disappeared for fast movements, where planning and control would have less time to overlap. Summing short-range processes at different timescales can produce 1/f-like noise. As planning is a slower-moving process and control faster, present results suggest that, with enough time for both planning and control, 1/f noise in aiming may arise from a similar summation of processes. Potential limitations of time series length in the present task are discussed.

Movement kinematics in prehension are affected by grasping objects of different mass

Previous research has identified that prehension is composed of a reach and a grasp component and that the position and size of the object can independently affect each. However, no effects on prior to contact prehension kinematics have been reported for manipulations in object mass. We felt that this 'lack of a finding' was surprising, as a more accurate grip position on heavier objects would prevent slippage and rotation when lifting the object. Therefore, we hypothesized that increased object mass would effect the grasp component movement kinematics prior to contact in preparation for a stable final grip placement on the object. We report two experiments in which participants reached, grasped and lifted objects of various size and mass, and their movement kinematics were recorded using a motion tracking system. The results showed that the mass of the object significantly influenced prior-to-contact grasp kinematics. Both studies showed that the heavy compared to light objects caused increased peak grasp aperture, a final finger and thumb placement on the object that more closely passed through the object centre of mass, increased lift delay and reduced peak lift velocity. The data are discussed in terms of how object mass influences the reach, grasp and lift components of prehensile movement.

Metamers in the haptic perception of heaviness and moveableness

It is hypothesized that heaviness perception for a freely wielded nonvisible object can be mapped to a point in a three-dimensional heaviness space. The three dimensions are mass, the volume of the inertia ellipsoid, and the symmetry of the inertia ellipsoid. Within this space, particular combinations yield heaviness metamers (objects of different mass that feel equally heavy), whereas other combinations yield analogues to the size-weight illusion (objects of the same mass that feel unequally heavy). Evidence for the two types of combinations was provided by experiments in which participants wielded occluded hand-held objects and estimated the heaviness of the objects relative to a standard. Further experiments with similar procedures showed that metamers of heaviness were metamers of moveableness but not metamers of length. A promising conjecture is that the haptic perceptual system maps the combination of an object's inertia for translation and inertia for rotation to a perception of the object's maneuverability.