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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.

In this chapter, you learned how to create two ballistics applications. It is important to understand how they are the same and how they are different. The programming techniques and HTML5 features include programmer-defined objects setInterval to set up a timing event for the animation, as done for the bouncing ball building an array using the push method and using the array as a list of what to display modifying arrays using the splice method the use of trig functions with calculations to rotate the cannon and to resolve the horizontal and vertical velocities so as to simulate gravity using a form for player input handling mouse events (mousedown, mousemove, mouseup), with addEventListener to obtain player input move drawing arcs, rectangles, lines and images on a canvas

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.

A mapping discrete element method is presented to study dynamic behaviors of the vibrating plate-particle coupling system. The continuum is partitioned into a mesh of mass points and simulated by the discrete element method, where the mass, stiffness and damping is mapped from the global mass, stiffness and Rayleigh damping matrix in the finite element method. The coupling between the continuum and the discrete particle material is realized by expanding the surface mass points into spheres. Therefore, the continuum's internal force and deformation can be accurately calculated whilst using the efficient spherical contact detection to couple and interact with particles. In the vibrating plate-particle system, the non-linear phenomena observed during the experiment are further studied by the proposed method. The results show that the velocity distribution of the particle system changes significantly when the jump phenomenon occurs, and the disruption of the uniform motion of the particle system by the vibrating plate is one of the key factors that creates the jump phenomenon. Furthermore, it is noticed in the simulation that the movement of particles above the plate is similar to bouncing ball causing frequency and period doubling phenomenon. Moreover, a linear region is found in the low frequency band, where the particles additional effects on the mass and stiffness of the plate are evident and the excitation amplitude has a lesser effect on power dissipation compared to other frequency bands.

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.

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

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.

We consider the problem on the semiclassical spectrum of the operator $$\nabla D(x)\nabla $$ with Bessel-type degeneration on the boundary of a two-dimensional domain (semirigid walls). It is well known that the asymptotic eigenfunctions associated with Lagrangian manifolds can be constructed using a modification of the Maslov canonical operator. We obtain asymptotic eigenfunctions associated with the simplest periodic trajectories of the corresponding Hamiltonian system with reflections on the domain boundary.

We develop a geometric interpretation for solutions to the Bolza problem in optimal control for systems subject to hybrid dynamics. In particular, the idea of a hybrid Lagrangian submanifold is introduced. These submanifolds are invariant under the hybrid Hamiltonian flow arising from the extended maximum principle for hybrid systems. Solutions to the hybrid optimal control problem are characterized from backward propagating these submanifolds under the hybrid Hamiltonian flow. This approach side-steps issues of multi-valuedness and singularities. This paper ends with a brief example of the controlled bouncing ball to illustrate the theory.

Material characterization of brittle and ductile materials, by means of determining characteristic material parameters such as hardness, elastic moduli or yield strength, is of significance to the scientific community. The evaluation of indentations on micro- and macro-scale can be employed to characterize materials but is governed by highly sensitive acquisition hardware and complex analysis. Profound analytical, experimental, and numerical approaches exist to evaluate the impact of spherical indenters on a plane surface but require a deep knowledge of plasticity and computational mechanics. This work aims to provide a generalized analysis tool, which is based on fundamental Newtonian mechanics, to be applied on brittle and ductile materials of homogeneous and heterogeneous constitution. Based on bouncing ball measurements, the coefficient of restitution is evaluated to determine the homogeneity and degree of plasticity of the selected material. The measurements are supported with additional physical (e.g., electron micrographs, velocimetry) and numerical (Finite Element) investigations. It can be demonstrated that the evaluation of the bouncing trajectories provides essential information on the plasticity and topology of the selected material and leads to adequate results compared to complex experimental and numerical analysis.

Traditional physics-based contact models have been widely used for describing various contact phenomena such as robotic grasping and assembly. However, difficulties in carrying out contact parameter identification as well as the relatively low measurement accuracy due to complex contact geometry and surface uncertainties are the limiting factors of the physics-based contact modeling methods. In this paper, we present a novel hybrid contact modeling (HCM) method as an endeavor to discover models that can more accurately simulate practical contact scenarios than traditional physics-based contact models. The proposed method is implemented by combining a physics-based contact model and a data-driven error model. This approach is validated by using simulations of a bouncing ball, a flat-shot, and a three-dimensional (3D) peg-in-hole. The results demonstrate the feasibility and consistent performance of the HCM method.

A collision between two bodies is a usual phenomenon in many engineering applications. The most important problem with the collision analysis is determining the hysteresis damping factor or the hysteresis damping ratio. The hysteresis damping ratio is related to the coefficient of restitution. In this paper, an explicit expression is determined for this relation. For this reason, a parametric expression is considered for the relation between the deformation and its velocity of the contact process. This expression consists of two unknown constants. Using the energy balance, a new explicit parametric expression between the hysteresis damping factor and the coefficient of restitution is derived. For determining the unknown constants, the root mean square (RMS) of the hysteresis damping ratio of this new expression with respect to the numerical model is minimized. This new model is completely suitable for the whole range of the coefficient of restitution. So, the new model can be used in the hard and soft impact problems. Finally, three numerical examples of two colliding bodies, the classic bouncing ball problem, the resilient impact damper, and a planar slider–crank mechanism, are presented and analyzed.

We modify a traditional bouncing ball activity for introducing exponential functions by modeling the time between bounces instead of the bounce heights. As a consequence, we can also model the total time of bouncing using an infinite geometric series.

Animation is the technique of producing a sequence of still pictures fast enough that our eye–mind connection interprets the sequence as motion. This chapter introduces the topic of animation by presenting four sketches. You’ll first implement a bouncing ball, namely a circle that moves in a window, changing direction (bouncing) off the sides. You’ll then implement a set of three bouncing balls, a bouncing pentagon, and a bouncing polygon in which the user can change the number of sides by pressing the mouse button.

In this paper, we consider a mechanical counterexample which satisfies all conditions of Moser’s twist theorem except the smoothness condition. The model (also called ping-pong model) is the vertical motion of a bouncing ball on a plate which moves in the vertical direction as a $$C^{1+\alpha }$$ -smooth periodic function with $$0\le \alpha

Summary 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.

In this paper, a billiard type of system is studied. The system describes the motion of a particle in a bounded domain under dissipation and periodic potential. The collisions between the particle and the boundary are elastic. The approximation scheme of Benci and Giannoni (Ann Inst H Poincare Anal Non Lineaire 6(1), 73–93, 1989) for elastic bounces in conservative systems is extended to time periodic systems with dissipations, and the existence of periodic bounce solutions is proved. Moreover, it is proved that the results still hold when the domain is unbounded, if the potential is coercive. As applications of the results, the existence of periodic bounce orbits are shown in the Fermi model, bouncing ball model with dissipation, and a class of multi-degrees-of-freedom impact systems.

In this paper, consensus for a network of dynamical systems which communicate over data-rate constrained communication channels is considered. Each system in the network is equipped with a sensor and an actuator which are at locations remote from one another. In order to transmit the state of any system to any of the actuators, the sensors use data-rate constrained communication channels. The actuators then use the messages to determine control inputs such that the systems achieve a particular type of consensu. Sensor/actuator pairs that achieve that particular type of consensus are called consensus protocols. In this contribution, an efficient in terms of required data-rates consensus protocol is presented. For the protocol, a theorem proving conditions on the sufficient minimal data-rates to implement it is provided. The sufficient data-rate is proven to depend on the singular values of the linear part of the mapping of the systems in the network. Finally, an example is provided in the form of consensus for a network of harmonically forced bouncing ball systems, for which an analytical bound is provided on the sufficient outgoing channel rates.

We discover that stable high-Q bouncing ball modes with tight lateral confinement and whole-body light–matter interaction can exist in an imperfectly aligned, wedged plano–plano FP (WFP) cavity by ...

Globally, tractor overturning accidents are a serious problem in agriculture. Tractor overturning not only threatens the life and health of famers but it can be major obstruction towards farm automation. In Japan, small tractors are used in harsh running environments, such as on rough farm roads, steep passage slopes, and narrow inclined side paths. Violent vibrations can occurs in the tractor and the wheels of the tractor sometimes depart from the ground. This phenomenon is called “bouncing” and leads to impact dynamics which are equivalent to the bouncing ball. Bouncing is typical nonlinear dynamics which causes excessive vibration, along with sideslip and poor steering performance which can lead to overturning. Bouncing becomes particularly serious when tractors run on steep slopes such as from a paddy field to a farm road. The present study analysed an impact dynamics model of a nonlinear two-dimensional bouncing tractor on steep passage slopes solved using numerical simulation. First, frequency response analysis was employed to investigate basic characteristics of nonlinear bouncing tractor model. Discontinuous responses, which are typical of nonlinear phenomenon, were observed in the frequency response curve. Next, numerical experiments of the tractor running on a steep passage slope were conducted based on a real accident case that occurred in Japan. Travel velocity of tractor and angle of passage slope were taken as control parameters and varied. Discontinuous responses were observed as control parameters were varied. Results indicated that nonlinear bouncing tractor model has strong parameter sensitivity which can cause sudden unpredictable phenomenon, such as violent vibration and sideslip, and overturning accidents.

We construct asymptotic eigenfunctions for the two-dimensional Schrodinger operator with a potential in the form of a well that is mirror-symmetric with respect to a line. These functions correspond to librations on this line between two focal points. According to the Maslov complex germ theory, the asymptotic eigenfunctions in the direction transverse to the line with respect to which the well is symmetric have the form of the appropriate Hermite-Gauss mode. We obtain a global Airy-function representation for the asymptotic eigenfunctions in the longitudinal direction.

Timing is essential for various behaviors and relative to vision, audition is considered to be specialized for temporal processing. The present study conducted a sensorimotor timing task that required tapping in synchrony with a temporally regular sequence and a perceptual timing task that required detecting a timing deviation among a temporally regular sequence. The sequence was composed of auditory tones, visual flashes, or a visual bouncing ball. In the sensorimotor task, sensorimotor timing performance (synchronization stability) of the bouncing ball was much greater than that of flashes and was comparable to that of tones. In the perceptual task, where perceptual timing performance of the bouncing ball was greater than that of flashes, it was poorer than that of tones. These results suggest the facilitation of both perceptual and sensorimotor processing of temporal information by the bouncing ball. Given such facilitation of temporal processing, however, audition is still superior over vision in perceptual detection of timing.

Made available in DSpace on 2022-04-28T17:21:57Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-03 Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) 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. UFSJ Univ Fed Sao Joao del Rei, Dept Estat Fis & Matemat, Rod MG 443,Km 7, BR-36420000 Ouro Branco, MG, Brazil UFSJ, Programa Posgrad Fis, Ouro Branco, MG, Brazil UNESP Univ Estadual Paulista, Dept Fis, Av 24A,1515 Bela Vista, BR-13506900 Sao Paulo, Brazil UNESP Univ Estadual Paulista, Dept Fis, Av 24A,1515 Bela Vista, BR-13506900 Sao Paulo, Brazil CNPq: 301318/2019-0 FAPESP: 2019/14038-6

The effect of the sloshing motion of liquid in a tank on the vertical transient motion of a single degree of freedom system is investigated. Step release tests of a vertically vibrating structure, including a tank containing liquid, demonstrate that added damping from the sloshing motion depends upon the amount of fluid in the tank and the maximum acceleration. The maximum amount of damping was observed at a 50% fill level and the system showed three distinct response regimes during the transient decay, all related to different motions of the fluid. The first response regime, immediately at the start of the transient, is considered to be the most important to exploit for aircraft gust loads alleviation due to its dominant role in the overall energy dissipation balance. Further, to advance the understanding of the modelling and predictive capabilities, coupled fluid-structure models of two opposing levels of fidelity were developed and evaluated. Namely, smoothed particle hydrodynamics (SPH) and an equivalent mechanical model (EMM) based on a bouncing ball model were considered to represent the fluid motion in the tank during the experiment. Both models are shown to provide good predictive capability in the initial impacting sloshing mode while the subsequent flow regime can be predicted with the SPH model only. The findings in this paper open routes towards improved coupled fluid-structure models and their use in improved aeroelastic wing design.

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 $$\eta \propto \varGamma ^{-1}$$ .

Traditional vibration sensor of ship machinery using cable for power supply cannot meet the requirements of a large number of distributed sensors of the intelligent ship. A bouncing-ball based triboelectric nanogenerator (BB-TENG) to be used as a self-powered vibration frequency monitoring sensor is proposed. In the sensing test, the vibration frequency of 15 ∼ 50 Hz under different amplitudes can be measured accurately. The frequency calculation of the voltage signal can accurately reflect external vibration frequency, while the change of short-circuit current has linear relationship with the frequency, and the correlation coefficient is about 0.99. In addition, electrical signal test results and photos taken by high-speed cameras show that the limit of the available detection frequency of BB-TENG increases with the increase of amplitude and support height. The electrical output of BB-TENG under different working conditions are tested, which provides the basis for selecting suitable BB-TENG according to different vibration characteristics.

With the development of intelligent ship, types of advanced sensors are in great demand for monitoring the work conditions of ship machinery. In the present work, a self-powered and highly accurate vibration sensor based on bouncing-ball triboelectric nanogenerator (BB-TENG) is proposed and investigated. The BB-TENG sensor consists of two copper electrode layers and one 3D-printed frame filled with polytetrafluoroethylene (PTFE) balls. When the sensor is installed on a vibration exciter, the PTFE balls will continuously bounce between the two electrodes, generating a periodically fluctuating electrical signals whose frequency can be easily measured through fast Fourier transform. Experiments have demonstrated that the BB-TENG sensor has a high signal-to-noise ratio of 34.5 dB with mean error less than 0.05% at the vibration frequency of 10 Hz to 50 Hz which covers the most vibration range of the machinery on ship. In addition, the BB-TENG can power 30 LEDs and a temperature sensor by converting vibration energy into electricity. Therefore, the BB-TENG sensor can be utilized as a self-powered and highly accurate vibration sensor for condition monitoring of intelligent ship machinery.

[EN] Learning is deeply rooted in the social environment of pupils and can flourish in a well-designed optimal learning environment in schools. Participative teaching-learning requires activities set in many different contexts, developing the grain-size pieces of knowledge and chaining of the fragments by causal chaining, time sequences and mathematical similarities. Based on the Knowledge-in-Pieces theory by diSessa, we focus on the development of the ability to think in terms of the exponential function, in Physics education from the age of 12. Main ideas are supported by experience with one activity with a bouncing ball designed for pupils at the age of 12. The activity is focused on topics such as measuring quantity, unit, method of measurement. Pupils propose which features of the ball can be investigated and measured. After this introduction, a quantity related to the bouncing is put forward in the activity. It is a dimensionless quantity, which pupils can express as a percentage. Pupils empirically investigate the bouncing of a ball. In the extension, at a higher age, the graph of maximal height vs the number of bounces, pupils discover the same shape they have seen in a water-cooling experiment. The activity was tested on a small sample of pupils, and some interesting results have been noticed. At the end of this contribution, we offer a list of other contexts naturally involving the exponential shape graph applicable in science education., The authors are grateful to support from the Ministry of Education of Slovak Republic, project VEGA 1/0273/19, Tutoring and Scaffolding in the Preparation of Pre-Service Physics Teachers.

Made available in DSpace on 2021-06-25T10:45:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Introductory mechanics courses use the bouncing ball model to familiarize students with the principles of binary inelastic collisions. Nonetheless, in undergraduate courses, the modeling of binary systems typically disregards the time of contact and the effects of gravity, which yields to a constant coefficient of restitution (COR) and, as a consequence, prevents students from elucidating the real dependence of COR with impact speed. In this work, we proposed a simple experimental setup to investigate the impact dynamics of a spring-mass body that bounces on a rigid plate as well as a theoretical framework that captures the velocity dependence of the COR for low-impact speeds. Our analytical expression for the COR highlights the role-played by gravity, impact speed and collision time on the collision dynamics. Our results suggest that the inclusion of gravity force allows an adequate estimation of the critical impact speed and maximum deformation distance, crucial parameters to differentiate between repulsive and attractive interaction regimes. Our experimental setup enables the clarification of several key concepts of mechanics while it is easy to be performed in most undergraduate laboratories. Departamento de Ciencias Universidad Privada Del Norte Facultad de Ciencias Físicas Universidad Nacional Mayor de San Marcos Institute of Physics Academy of Sciences of the Czech Republic, Cukrovarnická 10 Instituto de Física Teórica Universidade Estadual Paulista (UNESP), Rua Dr. Bento T Ferraz, 271 Instituto de Física Teórica Universidade Estadual Paulista (UNESP), Rua Dr. Bento T Ferraz, 271

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.

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.

This paper basically addresses real time neural network control of a peculiarly mechanical system using multi-channel audio input. The aim distinctly is to balance a bouncing ball on a wooden frame by taking into account the acoustic feedback from sensors mounted on the corners of the wooden frame. We first considered the audio data from sensors at an initially known position to create a Mel-Spectrogram that results as the sole input of a recurrent neural network. In our application, the essential subtle differences between the spectrograms from multiple sources are used to drive the position of actuators which determine the position and rotation of a parallel manipulator. We present a real time simulated implementation of this method which operates under physically accurate conditions.

The bouncing ball system is a simple mechanical collision system that has been extensively studied for several decades. In this study, we investigate the bouncing ball’s dynamics both numerically and experimentally. We implement the system using a table tennis ball and paddle vibrated by a shaker. We focus on the relationship between the ball’s maximum bounce height in the long time interval and the paddle’s vibration frequency, observing several stepwise height changes for frequencies of 25–50 Hz, noting this significant characteristic in both our experiments and numerical simulations. We concentrate on this paddle frequency interval because the phenomenon is easy to handle in numerical simulations. Because the observed phenomenon has a simple order, it can be universal and appear in a large class of collision dynamics. Possibly, some researchers have investigated the bouncing ball system in which the nonsmooth maximum bounce height changes occur. However, they may have failed to notice the changes because the maximal height of the ball was not considered.

With the progress of science and technology, virtual reality, human-computer interaction, network big data and other research fields and related products have entered people's lives in large quantities. At the same time, the relationship between people and space, network and data has also changed. People expect to realize the two-way flow of information in the different space between virtual and real through a more natural and harmonious interaction. This work will start from the most basic “3I” characteristics of virtual reality (immersion, interaction, imagination) and combine with the fourth “I” (Intelligence) characteristics, in order to realize the audience's experience process in multidimensional space such as vision, hearing and touch through immersive projection space (CAVE) and interactive sensor device. It tries to create a virtual reality space for the audience to empathize with and be understood by machines. When the audience approaches the work, the printer in the space prints words and phrases at random, and the audience makes the bouncing ball that projected on the wall make corresponding display feedback through the voice interaction of reading or dialogue. When audiences by changing move their arms, the bouncing spheres and countless particles would be deformed and displaced. The whole work intends to show the communication relationship between the individual people and machines. Machines are also trying to communicate and learn about human behavior.

This paper investigates trajectory prediction for robotics, to improve the interaction of robots with moving targets, such as catching a bouncing ball. Unexpected, highly-non-linear trajectories cannot easily be predicted with regression-based fitting procedures, therefore we apply state of the art machine learning, specifically based on Long-Short Term Memory (LSTM) architectures. In addition, fast moving targets are better sensed using event cameras, which produce an asynchronous output triggered by spatial change, rather than at fixed temporal intervals as with traditional cameras. We investigate how LSTM models can be adapted for event camera data, and in particular look at the benefit of using asynchronously sampled data., 5 pages, 5 figures, 1 table, paper accepted for presentation at the 2nd IEEE International Conference on Artificial Intelligence Circuits and Systems (AICAS2020)

In this paper, we propose two numerical approaches to propagate the uncertainty of a hybrid system according to its Fokker-Planck equation, which is generalized for stochastic hybrid systems and expressed as an integro- partial differential equation. The first approach is to convert the Fokker-Planck equation into an ordinary differential equation through discrete Fourier transform; the second is to split the equation into the continuous evolution part and the discrete transition part, to solve them independently, and to combine them using the splitting technique. We apply the two proposed methods to the classic bouncing ball model, and validate them by comparing with a Monte Carlo simulation. In this numerical example, we demonstrate computational benefits of the proposed methods over the Monte Carlo method.

This paper formulates the bouncing ball system in gravitational field, where a ball bounces between two rigidly connected harmonic limiters, by the impulsive differential equations with state constraints. By an extended Lyapunov-like stability theory for impulsive systems, we obtain the sufficient conditions guaranteeing the ball will stay on the lower limiter after a finite time but maybe an infinite number of impacts. The upper bound of the finite time is also estimated by theoretical analysis. Some numerical simulations are given to verify the theoretical validity.

A continuous contact force model, which considers the influence of constant external forces, is presented for the dynamic analysis of a multibody system. In this model, the Hertz contact law is applied to represent the nonlinear nature of contact, and a damping force is derived for evaluating the energy loss during impact. Together with the restitution coefficient, the external force influence factor defined in this paper is required for calculating the hysteresis damping factor associated with damping force. Moreover, the expression of hysteresis damping factor is deduced based on the energy-based method, which is adopted frequently in literature, and then it is improved by a weighted combination method with an exponential function due to the fact that the energy-based method has great errors when the restitution coefficient is low. Meanwhile, the exponential function is obtained by fitting the parametric surface of hysteresis damping factor gained from a numerical approach. Finally, four contact force models, including the new model, are utilized to compare the dynamic response of a special bouncing ball. The results illustrate that the described model is more suitable for impact analysis in multibody dynamics. In addition, the external forces and the energy loss are the main reasons for the multibody system to enter a steady contact state from repeated impact state.

A vibro-impact mechanical system comprising of a ball moving freely between two dielectric membranes located at a certain distance from each other is studied. The system generates electricity when the ball moving due ambient vibrations impacts one of the membranes. The energy harvesting principle of the proposed system is explained and then used to formulate a numerical model for estimating the system output voltage. The dynamic behavior and output performance of the system are thoroughly studied under a harmonic excitation, as well as different initial conditions and various values of the restitution coefficient of the membranes. The delivered research results are useful for selecting the system parameters to achieve its optimal output performance in a realistic vibrational environment. Potential application of the proposed system for energy harvesting from car engine vibrations is presented.

International audience; The problem of interval observer design is studied for a class of linear impulsive systems. Ranged and minimum dwell-time constraints are considered under detectability assumption. The first contribution of this paper lies in designing interval observers for linear impulsive systems under ranged and minimum dwell-time constraints, and investigating positivity of the estimation error dynamics in addition to stability. Several observers are designed oriented on different conditions of positivity and stability for estimation error dynamics. The boundedness of the estimation error (input-to-state stability property) and the observer stability conditions are stated as infinite-dimensional linear programming problems. Next, an output stabilizing feedback design problem is discussed, where the stability is checked using linear matrix inequalities (LMIs). Efficiency of the proposed approach is demonstrated by computer simulations for a commercial electric vehicle equipped with a low power range extender fuel cell, a bouncing ball, an academic linear impulsive system and for Fault Detection and Isolation (FDI) and Fault-Tolerant Control (FTC) of a power split device with clutch for heavy-duty military vehicles.

In this article, we study the higher-order Moreau's sweeping process introduced in [1], in the case where an exogenous time-varying functionu(·) is present in both the linear dynamics and in the unilateral constraints. First, we show that the well-posedness results (existence and uniqueness of solutions) obtained in [1] for the autonomous case, extend to the non-autonomous case whenu(·) is smooth and piece-wise analytic, after a suitable state transformation is done. Stability issues are discussed. The complexity of such non-smooth non-autonomous dynamical systems is illustrated in a particular case named the higher-order bouncing ball, where trajectories with accumulations of jumps are exhibited. Examples from mechanics and circuits illustrate some of the results. The link with complementarity dynamical systems and with switching differential-algebraic equations is made.

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.

By continuously varying certain geometric parameters γ of the totally desymmetrized quantum Sinai billiard, we study the formation of the so-called soliton-like structures in the spectra of the resulting family of systems. We present a detailed characterization of the eigenstate ψn morphologies along such structures. Usually, scarring and bouncing ball mode states are expected to fully explain the solitons. However, we show that they do not exhaust all the possibilities. States with strong resemblance to very particular solutions of the associated integrable case ( 45°– 45° right triangle) also account for the ψn’s. We argue that for the emergence of the solitons, in fact, there must be an interplay between the spatial localization properties of the soliton-related ψn’s and the rescaling properties of the billiards with γ. This is illustrated, e.g., by comparing the behavior of the eigenwavelengths along the solitons and the billiard size dependence on γ. Considerations on how these findings could extend to other type of billiards are also briefly addressed.

We have performed a video-based STEM experiment of a bouncing ball using a force plate logger sensor and Neulog application. Our objective was to observe the students understanding the relationship between impulse and momentum, examine this relation by bouncing a ball on a force plate logger sensor, and calculate impulse and change in momentum. All the data, such as raw data of force and time, video recorded, and the questions given to the 10th-grade senior high school students. Then, their answer will be analyzed to confirm the understanding of momentum during the learning process by video-based STEM experiments.

This paper presents the chattering through the singularity point of view for the first time. The main novelty of this article is that impact moments are considered as a singularity phenomenon. A bouncing ball, an inverted pendulum and a hydraulic relief valve models are considered for the study. Moreover, the behavior of solutions of a spring-mass system is studied for the small mass. Simulations are given to support the theoretical analysis.

A new approach for modeling nonlinear impulsive system is suggested based on nonstandard analysis. Basic properties of the hyperreals in nonstandard analysis are revisited. Depending on the convergence rate of infinitesimals in hyperreals, a new extended real space is proposed, which extends the one dimensional real line to a countably infinite dimensional extended real space. Generalized functions are defined via a sequential approach on the extended space, which yields a class of Heaviside functions and singular functions. By using the extended functions, a causal way for characterizing jumps in discontinuous system follows. We illustrate the usefulness of the theoretical development by analyzing three simple cases of impulsive affine system: (1) scalar case, (2) multi-dimensional case, and (3) one dimensional horizontal bouncing ball. The results suggest not only the existence of such infinitesimal models within the jump but also how to detour the equilibrium point while connecting the discontinuous state at the impact.

The paper is concerned with observation of discrete-time, nonlinear, deterministic, and maybe chaotic systems via communication channels with finite data rates, with a focus on minimum data-rates needed for various types of observability. With the objective of developing tractable techniques to estimate these rates, the paper discloses benefits from regard to the operational structure of the system in the case where the system is representable as a feedback interconnection of two subsystems with inputs and outputs. To this end, a novel estimation method is elaborated, which is alike in flavor to the celebrated small gain theorem on input-to-output stability. The utility of this approach is demonstrated for general nonlinear time-delay systems by rigorously justifying an experimentally discovered phenomenon: Their topological entropy stays bounded as the delay grows without limits. This is extended on the studied observability rates and appended by constructive finite upper bounds independent of the delay. It is shown that these bounds are asymptotically tight for a time-delay analog of the bouncing ball dynamics.

A dynamic model to investigate the dynamics and vibration responses of angular contact ball bearings with ball defects is proposed. In the proposed model, each ball has 6 degrees of freedom (DOFs), meaning that the three-dimensional motion of balls is considered. The results show that whether a ball hit a race and the frequency property of the envelope spectrum largely depend on the geometrical characteristics and operating conditions. This increases the difficulty in diagnosing the ball defect when using vibration-based monitoring techniques. The current investigation suggests that the vibration response simulations should be carried out to investigate the vibration mechanism and to diagnose the ball defect more effectively.