Bouncing Ball Research Articles

A comparison of the effects of haptic and visual feedback on presence in virtual reality

In the current consumer market, Virtual reality experiences are predominantly generated through visual and auditory feedback. Haptics are not yet well established, but are increasingly introduced to enhance the user’s sense of ‘reality’. With haptic (vibrotactile) feedback now part of the built-in mechanism of VR consumer devices, there is an urgent need to understand how different modalities work together to improve the user experience. This paper reports an experiment that explores the contributions made to participants’ sense of presence by haptic and visual feedback in a virtual environment. Participants experienced a virtual ball bouncing on a virtual stick resting across their avatar hands. We found that presence was enhanced when they could both see and feel the ball’s action; with a strong suggestion that haptic feedback alone gave rise to a greater sense of presence than visual alone. Similarly, whilst visual or bimodal feedback enhanced participants’ ability to locate where the ball bounced on the stick, our results suggest that the action itself was more readily discerned haptically than visually.

Energy level structure of chaotic motion in bouncing ball system

We report our experimental and numerical results on the chaotic dynamics of a ball bouncing on a vertically vibrating plate. It is demonstrated that if the trajectories between collisions are classified according to the rescaled flight time, the chaotic attractor for the bouncing motion of the ball degrades into a regular structure composed of discrete energy levels in the phase space, and the motion states corresponding to these trajectories evolve into separate “microstates” populated on these levels. The probabilities of level transitions and the selection rules for the transitions are discussed. Then, the probability distribution of the energy dissipated during each collision is analyzed. It is found that there are discrete dissipation peaks in the energy dissipation spectrum. The origination of these dissipation peaks is analyzed from the perspective of level transitions.

Bio-inspired design of soft mechanisms using a toroidal hydrostat

Biology is replete with soft mechanisms of potential use for robotics. Here, we report that a soft, toroidal hydrostat can be used to perform three functions found in both living and engineered systems: gripping, catching, and conveying. We demonstrate a gripping mechanism that uses a tubular inversion to encapsulate objects within a crumpled elastic membrane under hydrostatic pressure. This mechanism produces gripping forces that depend predictably upon the geometric and materials properties of the system. We next demonstrate a catching mechanism akin to that of a chameleon’s tongue: the elasticity of the membrane is used to power a catapulting inversion process (≈400 m/s2) to capture flying objects (e.g., a bouncing ball). Finally, we demonstrate a conveying mechanism that passes objects through the center of the toroidal tube (∼1 cm/s) using a continuous inversion-eversion process. The hybrid hard-soft mechanisms presented here can be applied toward the integration of soft functionality into robotic systems.

Peningkatan kemampuan psikomotorik siswa dalam pembelajaran bola voli passing atas menggunakan teknik bola pantul pada siswa kelas X MAN 1 Kota Semarang

Angga Pratama, "Increasing the Psychomotor abilities of Students in Learning Top Passing Volleyball Using the Bounce Ball Technique in Class X Students of MAN 1 Semarang City". Essay. Department of Physical Education for Health and Recreation, Faculty of Social Sciences and Sport Education, PGRI University Semarang, 2020. Utvi Hinda Zhannisa, S.Pd., M.Ordan Ibnu Fatkhu Royana, S.Pd., M.Pd. Education is a very important field, especially in Indonesia. In the language of the definition of education is the process of changing the attitudes and behaviour of a person or group of people in an effort to mature humans through teaching and training efforts that are in accordance with the educational procedure itself. The purpose of this study was to determine the improvement of students' psychomotor abilities in learning volleyball using the bounce ball technique in class X students in MAN 1 Semarang City. The design used in this study belongs to the type of quantitative research. The use of a quantitative approach with pre-experimental methods. The population in this study were students of class X in MAN 1 Semarang City. The research sample was taken by means of random sampling. This research will involve 106 students of MAN 1 Semarang City. Based on the calculation, the sig value for pretest data obtained the sig value = 0.064> 0.05. For the posttest data, the sig = 0.056> 0.05 was obtained, so it can be concluded that the pretest and posttest data are homogeneous. The increase in the ability to pretest all volley passing is a minimum of 82,675%. for a maximum value of 89.33%. Data analysis and discussion obtained the following conclusions: There are differences in the psychomotor abilities of students in learning volleyball passing over before and after being given training using the bouncing ball technique in class X MAN 1 Semarang City. From these results, it can be concluded that there is an increase in the psychomotor abilities of students in learning volleyball passing overusing the bouncing ball technique in class X MAN 1 Semarang City students. The increase in the percentage of overpassing ability is 22.38%. It is better if the class X student coaches of MAN 1 Semarang City apply exercises using the bouncing ball technique considering that this exercise has been proven effective in improving students' psychomotor skills in learning volleyball passing over.

Effects of perinatal dioxin exposure on mirror neuron activity in 9-year-old children living in a hot spot of dioxin contamination in Vietnam

BackgroundFor 8 years, we have followed up a birth cohort comprising 241 mother-and-infant pairs living around the Da Nang airbase, a hot spot of dioxin contamination in Vietnam, and have reported the impacts of perinatal dioxin exposure on the neurodevelopment of children at various ages. In the present study, 9 years after birth, we investigated the effects of perinatal dioxin exposure on mu and theta rhythms by analyzing EEG power during the execution and observation of hand movements, which indicate mirror neuron system activity. MethodsOne hundred fifty-five 9-year-old children (86 boys and 69 girls) from the Da Nang birth cohort participated in the EEG examination with free viewing of hand movements. The dioxin levels in their mothers’ breast milk, measured 1 month after birth, were used as perinatal dioxin exposure markers. A log transform of the ratio of EEG power during execution or observation of the hand movements relative to the power during observation of a bouncing ball for theta and mu rhythms was used to evaluate mirror neuron activity. ResultsIn both brain hemispheres, the log power ratio in the theta band was significantly higher (i.e., less reduction of power) during observation of hand movements in girls exposed to high levels of TCDD. In boys, however, dioxin congeners other than TCDD, including HxCDDs and several PCDF congeners, contributed to increased log power ratios in the theta band. Particularly for PCDF congeners, the log power ratios in the lowest group among 4 exposure groups were lowest and significantly increased (i.e., decreasing reduction of power) with increasing dose. ConclusionPerinatal TCDD exposure may influence the mirror neuron system of the brain, which plays an important role for social-emotional behavior in children, particularly in girls living in a hot spot of dioxin contamination in Vietnam.

The Bouncing Ball and the Grünwald-Letnikov Definition of Fractional Derivative

Abstract This paper proposes a conceptual experiment embedding the model of a bouncing ball and the Grünwald-Letnikov (GL) formulation for derivative of fractional order. The impacts of the ball with the surface are modeled by means of a restitution coefficient related to the coefficients of the GL fractional derivative. The results are straightforward to interpret under the light of the classical physics. The mechanical experiment leads to a physical perspective and allows a straightforward visualization. This strategy provides not only a motivational introduction to students of the fractional calculus, but also triggers possible discussion with regard to the use of fractional models in mechanics.

Gripping, Catching, and Conveying With a Soft, Toroidal Hydrostat

This work demonstrates that a soft, toroidal hydrostat can be used to perform three functions found in both living and engineered systems: gripping, catching, and conveying. We first demonstrate a gripping mechanism that uses linear motion to drive the inversion of the toroid around objects, encapsulating them within a crumpled elastic membrane under hydrostatic pressure. This mechanism results in gripping forces ranging from 1–80 N, which depend predictably upon the geometric and material properties of the gripper and the object. We next demonstrate a catching mechanism akin to that of a chameleon’s tongue: the elasticity of the membrane is used to store mechanical energy and drive a rapid acceleration and inversion process (≈400 m/s2) to capture flying objects (e.g., a bouncing ball). Finally, we show how the soft topological structure can be implemented in a soft conveying mechanism which continuously inverts and passes objects through its center (~1 cm/s), serving a function like that of esophageal peristalsis (i.e., transporting objects through a tube), while eliminating the requirement of a lubricated interface and the coordinated actuation of a pressure wave. The hybrid hard-soft mechanisms presented here can be applied in the integration of soft functionality into conventional robotic systems for applications including the automation of agricultural and biological research processes. More generally, we show how inflatable structures comprising soft polymeric films arranged in complex topologies provide a promising approach to designing soft robotic systems with novel, bio-inspired functionality.

Nonlinear reduced-order model for vertical sloshing by employing neural networks

The aim of this work is to provide a reduced-order model to describe the dissipative behavior of nonlinear vertical sloshing involving Rayleigh–Taylor instability by means of a feed forward neural network. A 1-degree-of-freedom system is taken into account as representative of fluid–structure interaction problem. Sloshing has been replaced by an equivalent mechanical model, namely a boxed-in bouncing ball with parameters suitably tuned with performed experiments. A large data set, consisting of a long simulation of the bouncing ball model with pseudo-periodic motion of the boundary condition spanning different values of oscillation amplitude and frequency, is used to train the neural network. The obtained neural network model has been included in a Simulink® environment for closed-loop fluid–structure interaction simulations showing promising performances for perspective integration in complex structural system.

Research on dynamics of bouncing ball in triboelectric nanogenerator

Bouncing ball based Triboelectric Nanogenerator (BB-TENG) can be used to harvest vibrational energy and sense signal for self-powered sensor in the non-resonant zone because of its non-spring vibration system. The energy harvesting efficiency and sensing effectiveness are significantly affected by the dynamics of the bouncing ball. However, due to the chaotic and nonlinear mechanics, the dynamics of the bouncing ball inside BB-TENG and the corresponding influencing factors have not yet been revealed, which restricts the development of high-efficiency BB-TENG. In this work a method based on dynamics simulation and test bench experiment is to be proposed and the ‘Takeoff’, ‘Well-Contact’, ‘Self-Spin’, and ‘Rich-Contact’ of the bouncing ball with the plate electrodes will be investigated. The kinetic model established based on the Automatic Dynamic Analysis of Mechanical Systems (ADAMSs) is verified through experiments to confirm the reliability of the simulation results. It is found that ‘Well-Contact’ of the bouncing ball makes BB-TENG harvest energy efficiently. The factors for ‘Well-Contact’ and their influence are investigated, and the critical frequencies for ‘Well-Contact’ of the bouncing ball at each vibration excitation amplitude are obtained. ‘Self-Spin’ of the bouncing ball produced by unbalanced excitation torque is found to increase energy harvesting, and the excitation frequency significantly determines the energy of the ‘Self-Spin’. When the external excitation acceleration reaches a critical value, the ‘Rich-Contact’ of the bouncing ball is found, and the amount of charge transfer for BB-TENG will not increase, which is termed saturated condition. Therefore, the results of this work help improve the design and application of high-efficiency BB-TENG.

Dynamical aspects of a bouncing ball in a nonhomogeneous field.

We study some dynamical properties of a charged particle that moves in a nonhomogeneous electric field and collides against an oscillating platform. Depending on the values of parameters, the system presents (i) predominantly regular dynamics or (ii) structures of chaotic behavior in phase space conditioned to the initial conditions. The localization of the fixed points and their stability are carefully discussed. Average properties of the chaotic sea are investigated under a scaling approach. We show that the system belongs to the same universality class as the Fermi-Ulam model.

Evaluation of an Anthropometric Fast Bowling Machine

The use of bowling machines to train batsmen whether it be indoors or outdoors has increased significantly. In the absence of bowlers, batsmen can bat for hours without any bowlers getting tired. The designs of these machines are often a derivative of ball projection machines used for other sports such as tennis. Reviewed literature highlights the deficit in visual information in the form of an arm and hand when using these machines. Hence a cricket bowling machine was developed with an arm and hand. The usability, functionality, repeatability, and accuracy of the cricket bowling machine with an arm and hand was tested which had been previously designed and built by Loutan Jr. (2016) at The University of Trinidad and Tobago. A trajectory model was developed for an indoor environment and experimentally validated with data collected from extensive testing of the bowling machine using Pitch Vision hardware and software. A design procedure had to be formulated to determine what test had to be done and the method of collecting data. The testing, data collection and validation of the model was done with the cricket bowling machine in its current state with minor changes to the hand. The release angle at which the ball leaves the hand was found to have a significant impact on the length (distance along the pitch the ball bounces) of the delivery. Finally, the bowling machine was able to bowl various lengths and varying speeds consistently. The variation in speed placed the machine in the category of medium-fast, that is, speeds between 120 km/h (75 mph) and 130 km/h (81mph). Doi: 10.28991/HIJ-2021-02-02-04 Full Text: PDF

Trajectory tracking of a bouncing ball in a triangular billiard by unfolding and folding the billiard table

In this paper, a feedback control law is proposed to solve the asymptotic tracking problem for a ball bouncing in a triangular billiard. This controller is designed by firstly transforming the billiard table into a surface on which the ball moves without experiencing any impact, i.e. by reflecting the billiard table rather than the ball trajectory and designing a position feedback controller based on such an unfolded billiard table. Furthermore, it is shown how such an infinite-billiard table can be mapped to the surface of a torus, thus leading to bounded trajectories of the ball.

A Hybrid Contact Model With Experimental Validation

Abstract This brief paper emphasizes on the experimental study of a hybrid contact model combining a traditional physical-based contact model and a data-driven error model in order to provide a more accurate description of a contact dynamics phenomenon. The physical-based contact model is employed to describe the known contact physics of a complex contact case, while the data-driven error model, which is an artificial neural network model trained from experimental data using a machine learning technique, is used to represent the inherent unmodeled factors of the contact case. A bouncing ball experiment is designed and performed to validate the model. The hybrid contact model can duplicate experimental results well, which demonstrates the feasibility and accuracy of the presented approach.

The Implementation Bounce Ball Games to Improve Students’ Set Pass Ability

This study aims to improve the volleyball set pass skills of students at Junior High School 19 Pontianak. It can be seen from the results of observations made by researchers and interviews with physical education teachers at the school. It can be seen that there are still many students who do not understand the basic techniques of set passing so that it affects the minimum completeness criteria value which is still below the average. The research method used is the classroom action research method which is carried out in two cycles consisting of the stages of planning, implementing, observing and reflecting. The results were an increase in volleyball passing skills using the method of playing bouncing ball in class VIII junior high school students 19 Pontianak, namely in the pre-cycle student completeness only reached 25%, then there was an increase in cycle I of 63% and there was an increase in cycle 2 to 78%. It can be concluded that applying the game of bouncing ball can improve the skills of set pass volleyball in 19 public junior high school students in Pontianak.

Effect of lateral confinement on the apparent mass of granular dampers

We study, via discrete element method simulations, the apparent mass (m, the ratio of a driving force to a resulting acceleration) and loss factor ( $$\eta$$ , the ratio of dissipated to stored energy) of granular dampers attached to a vertically driven, single degree of freedom mechanical system. Granular dampers (or particle dampers) consist in receptacles that contain macroscopic particles which dissipate energy, when they are subjected to vibration, thanks to the inelastic collisions and friction between them. Although many studies focus on $$\eta$$ , less work has been devoted to m. The apparent mass of granular dampers is an important characteristic since the grains, which are free to move or collide inside their receptacle, act as a non-constant and time-dependent mass which alters the mass of the main vibrating system in a non-trivial way. In particular, it has been recently demonstrated (Masmoudi et al. in Granul Matter 18:71, 2016) that m non-linearly depends on the driving acceleration $$\varGamma$$ according to a power law, $$m\propto \varGamma ^k$$ . Experiments using three-dimensional (3D) packings of particles suggest $$k=-2$$ . However, simulations with one-dimensional (1D) columns of particles on a vibrating plate and theoretical predictions based on the inelastic bouncing ball model (IBBM) suggest that $$k=-1$$ . These findings opened questions as to whether the apparent mass, which relies on how linear momentum is transferred from the damper to the primary system, depends on the dimensionality of the packing or on lateral interactions between walls and grains. Interestingly, $$\eta$$ was shown to follow a universal curve, $$\eta \propto \varGamma ^{-1}$$ , whatever the dimensionality and the constraints in the motion of the grains. In this work, we consider granular dampers without a lid under different confinement conditions in the motion of the particles (1D, quasi-1D, quasi-2D and full 3D). We find that the mechanical response of the granular damper (m and $$\eta$$ ) is not sensitive to the lateral confinement or dimensionality. However, we have observed two distinct regimes, depending on whether the driving frequency is above or below the resonant frequency of the primary system. In the inertial regime, $$\eta$$ decays according to the IBBM for all dimensions, $$\eta \propto \varGamma ^{-1}$$ , while m falls as $$\varGamma ^{-2}$$ for all dimensions, in agreement with Masmoudi’s experiments. However, the power law for m is valid only for moderate acceleration, before becoming negative at high accelerations. In the quasi-static regime, both m and $$\eta$$ display a complex behavior as functions of the excitation amplitude, but the mean trend is consistent with the IBBM predictions, i.e., $$m\propto \varGamma ^{-1}$$ and $$\eta \propto \varGamma ^{-1}$$ .

Overcoming the Obstacle of Time-dependent Model Output for Statistical Analysis by Nonlinear Methods

Modelica models represent static or dynamic systems. Their outputs can be scalar (numbers) or time-dependent (time series). Most advanced mathematical methods for the analysis of numerical models cannot cope with functional outputs. This paper aims at showing an efficient method to reduce a time-dependent output to a few numbers. The Principal component analysis is a well-established method for dimension reduction and can be used to tackle this issue. It relies however on a linear hypothesis that limits its applicability. We adapt and implement an existing method called the auto-associative model, invented by Stéphane Girard, to overcome this shortcoming. The auto-associative model generalizes PCA, as it projects the data on a nonlinear (instead of linear) basis. It also provides physically interpretable data representations. The difference in efficiency between both methods is illustrated in a case study, the well-known bouncing ball model. We perform output reduction and reconstruction using both methods to compare the completeness of information kept throughout the dimension reduction process. Doi: 10.28991/HIJ-2021-02-01-01 Full Text: PDF

"Mickey Mousing" in the Brain: Motion-Sound Synesthesia and the Subcortical Substrate of Audio-Visual Integration.

Motion-sound synesthesia is characterized by illusory auditory sensations linked to the pattern and rhythms of motion (dubbed “Mickey Mousing” as in cinema) of visually experienced but soundless object, like an optical flow array, a ball bouncing or a horse galloping. In an MRI study with a group of three synesthetes and a group of eighteen control participants, we found structural changes in the brains of synesthetes in the subcortical multisensory areas of the superior and inferior colliculi. In addition, functional magnetic resonance imaging data showed activity in motion-sensitive regions, as well as temporal and occipital areas, and the cerebellum. However, the synesthetes had a higher activation within the left and right cuneus, with stronger activations when viewing optical flow stimuli. There was also a general difference in connectivity of the colliculi with the above mentioned regions between the two groups. These findings implicate low-level mechanisms within the human neuroaxis as a substrate for local connectivity and cross activity between perceptual processes that are “distant” in terms of cortical topography. The present findings underline the importance of considering the role of subcortical systems and their connectivity to multimodal regions of the cortex and they strengthen a parsimonious account of synesthesia, at the least of the visual-auditory type.

Investigating t∞ for bouncing balls

A simple experiment carried out with readily available equipment is used to investigate the interesting physics that occurs when a ball is bounced on a flat surface and left to continue bouncing until it stops. A solution well known from introductory physics courses is that if a ball loses a fraction of its energy on each bounce, then it will bounce infinitely many times in a finite time interval. A convolutional model of the sound a bouncing ball makes is created using an impulse response function and a prediction based on energy loss that the sound amplitudes will decay linearly to zero as the ball stops bouncing. Strategies for data analysis using correlation and deconvolution with the impulse response function are shown to simplify the picking of bounce times. Observations from several data examples show that the convolutional model is a good description of the real data and that we observe a linear decrease in sound amplitude consistent with the model prediction.

Collision-enhanced friction of a bouncing ball on a rough vibrating surface

We describe experiments and simulations to investigate the dynamics of a ball bouncing on a rough vibrating surface. Directly measuring the impulse due to each bounce we find that the frictional interaction with the surface is strongly enhanced near to the side wall. The enhanced dissipation arises as a consequence of the coupling between the collision, rotation and surface friction. This dissipation, which for our experimental conditions was estimated to be up to three times larger than the more obvious inelastic collision, can result in an enhanced probability density near boundaries and particle–particle spatial correlations. Our findings imply that the effective particle collision properties cannot be considered independently of the surface’s frictional properties.

Effects of stickiness in the classical and quantum ergodic lemon billiard

We study the classical and quantum ergodic lemon billiard introduced by Heller and Tomsovic in Phys. Today 46(7), 38 (1993)PHTOAD0031-922810.1063/1.881358, for the case B=1/2, which is a classically ergodic system (without a rigorous proof) exhibiting strong stickiness regions around a zero-measure bouncing ball modes. The structure of the classical stickiness regions is uncovered in the S-plots introduced by Lozej [Phys. Rev. E 101, 052204 (2020)10.1103/PhysRevE.101.052204]. A unique classical transport or diffusion time cannot be defined. As a consequence the quantum states are characterized by the following nonuniversal properties: (i) All eigenstates are chaotic but localized as exhibited in the Poincaré-Husimi (PH) functions. (ii) The entropy localization measure A (also the normalized inverse participation ratio) has a nonuniversal distribution, typically bimodal, thus deviating from the beta distribution, the latter one being characteristic of uniformly chaotic systems with no stickiness regions. (iii) The energy-level spacing distribution is Berry-Robnik-Brody (BRB), capturing two effects: the quantally divided phase space (because most of the PH functions are either the inner-ones or the outer-ones, dictated by the classical stickiness, with an effective parameter μ_{1} measuring the size of the inner region bordered by the sticky invariant object, namely, a cantorus), and the localization of PH functions characterized by the level repulsion (Brody) parameter β. (iv) In the energy range considered (between 20000 states to 400000 states above the ground state) the picture (the structure of the eigenstates and the statistics of the energy spectra) is not changing qualitatively, as β fluctuates around 0.8, while μ_{1} decreases almost monotonically, with increasing energy.