Problem Of Motion Research Articles

Analysis of student perceptions of problem-solving learning and peer assessment

Problem solving is one of the mandatory skills for students in the 21st century, especially in physics subjects. This study aims to determine the students' ability to solve parabolic motion problems, to determine students' perceptions of learning in solving parabolic motion problems, to investigate the results of peer assessments carried out by students, and to determine students' perceptions of the implementation of peer assessment. This research method uses qualitative research procedures with a phenomenological approach. This research was conducted on 25 high school students in Ende district. The results of data analysis showed that the article met four indicators of problem-solving ability according to Polya, namely understanding the problem, planning a solution, solving the problem according to plan, and re-checking the evaluation results. The problem ability of students in this study was obtained with the results of 53.06 being included in the sufficient category. Future studies should give priority to providing instruction and training before giving peer assessment.

Evolution of rotations of a spheroid with cavity containing a viscous fluid in a resistive medium

The problems of the dynamics of rigid bodies with the fluid containing cavities are classical problems of mechanics. The interest to the problems of rotations of rigid bodies with the fluid-containing cavities increased with the development of the rocket and space technology. There is a necessity to study the problems of the dynamics of bodies with cavities containing a viscous fluid, to calculate the motion of spacecraft about the its center of mass, as well as their orientation and stabilization. The torques of forces of viscous fluid in cavity, acting on the body, are often relatively small and can be considered as perturbations. It is natural to use the methods of small parameter to analyze the dynamics of rigid body under the action of applied torques. The method applied in this paper is the Krylov--Bogoliubov asymptotic averaging method. The paper develops on approximate solution by means of averaging method to the system of Euler's equations with additional perturbation terms for a spheroid filled with a viscous fluid in a resistive medium. The numerical integration of the averaged system of equations is conducted for the body motion. The graphical presentations of the solutions are represented and discussed. The main objective of this paper is to extend the previous results for the problem of motion about a center of mass of a spheroid with a cavity filled with a fluid of high viscosity (in the absence of resistive medium). Evolution of perturbed Euler--Poinsot motion under the influence of small internal and external torques is studied. We present new qualitative and quantitative results of investigations of motion in a resistive medium of a nearly dynamically spherical rigid body with a cavity containing viscous fluid with small Reynolds number. We received the system of motion equations in standard form, which refined in square approximation by small parameter. The averaging method was applied to the nonlinear system equation of rotational motion. In this paper we present the input equations of motion, conduct an averaging procedure and receive the averaged equations which, being simpler than the original ones, describe the motion over the large time interval. We establish qualitative and quantitative properties of motion and provide a description of the evolution of the body motion. Results summed up in this paper make it possible to analyze motions of artificial satellites and celestial bodies under the action of small perturbation torques.

Adaptive Neural Network Control of Zero-Speed Vessel Fin Stabilizer Based on Command Filter

This paper proposes a zero-speed vessel fin stabilizer adaptive neural network control strategy based on a command filter for the problem of large-angle rolling motion caused by adverse sea conditions when a vessel is at low speed down to zero. In order to avoid the adverse effects of the high-frequency part of the marine environment on the vessel rolling control system, a command filter is introduced in the design of the controller and a command filter backstepping control method is designed. An auxiliary dynamic system (ADS) is constructed to correct the feedback error caused by input saturation. Considering that the system has unknown internal parameters and unmodeled dynamics, and is affected by unknown disturbances from the outside, the neural network technology and nonlinear disturbance observer are fused in the proposed design, which not only combines the advantages of the two but also overcomes the limitations of the single technique itself. Through Lyapunov theoretical analysis, the stability of the control system is proved. Finally, the simulation results also verify the effectiveness of the control method.

Adaptive coordinated motion constraint control for cooperative multi-manipulator systems

Constrained motion and redundant degrees of freedom control exist in a multi-manipulator collaboration system. In other words, the multi-manipulator collaboration technology must solve the problems of uncertain environment interaction and coordinated control. Few studies have been conducted on the coordination control of a multi-manipulator, and the control effect is not good. To solve the coordinated motion problem of the multi-manipulator cooperative system, this study divides the multi-manipulator coordinated motion into two forms, namely coupled and superimposed motions, and proposes an adaptive coordinated motion constraint scheme under different motion forms. The coupled and superimposed motions are investigated through coordinated handling and coordinated drawing circle tasks, respectively. The proposed coordinated control scheme has a good effect. Without position detection and positioning, the kinematic constraint algorithm can maintain the relative motion relationship between end-effectors. When an external disturbance occurs, the slave manipulator can automatically adjust based on the position of the main manipulator, avoiding error accumulation. The experimental results show a maximum trajectory tracking error of 2.131 mm and maximum attitude error of 0.176°, indicating that the proposed control scheme has strong adaptive ability and high control accuracy.

ОЦІНЮВАННЯ ГЕОМЕТРИЧНИХ ПАРАМЕТРІВ ПОЛЮСНОЇ СИСТЕМИ МАТРИЦІ ЕЛЕКТРОМАГНІТНОГО СЕПАРАТОРА

Purpose. The choice of the geometric dimensions ratios of system of matrix poles of electromagnetic polygradient separator to increase productivity with maintaining the reliability of extracting of ferromagnetic impurities from bulk material.Methodology. To solve the dynamic problem of motion of a ferromagnetic body in the working gap of pole system of matrix of polygradient separator under the influence of an external magnetic field the known methods of solving linear inhomogeneous differential equations are used. To confirm the reliability of obtained results the method of experimental research is used.Findings. The formulation of dynamic problem of movement of ferromagnetic body in the working gap of plate pole system of matrix of polygradient separator is carried out. Parametric equation for the trajectory of ferromagnetic body removal and a calculated relation connecting the main geometric dimensions of the system of matrix poles are obtained. The calculation results are confirmed experimentally and by operating practice of known magnetic separating devices.Originality. The mathematical description of working process of a polygradient electromagnetic separator with a plate matrix was further developed, which made it possible to obtain an analytical expression that takes into account the main geometric dimensions of the working space of matrix of separator.Practical value. Accounting of obtained analytical dependences between the length of separation zone and air gap, which characterizes the thickness of the separated material layer through which the ferromagnetic body must pass during the separation process, will ensure the necessary purity and productivity of separation.

Piezoelectric stick-slip actuators with flexure hinge mechanisms: A review

Piezoelectric stick-slip actuators (PSSAs) are famous for ultimate working condition adaptability, simple structure, and positioning accuracy. To meet the demand of industrial application, lots of PSSAs designed with flexure hinge mechanisms (FHMs-PSSAs) have been developed to realize the requirements of translational motion, rotational motion, multi-degree-of-freedom (multi-DOF) motion. The output performance of the FHMs-PSSAs has been greatly improved, including load capacity, speed, and accuracy; moreover, some approaches to solve the problem of the backward motion are provided as well. In this work, the working principle of FHMs-PSSAs is introduced, and the excitation signals applicable to FHMs-PSSAs are summarized. Based on the current research and development status, the progress of structure design of FHMs-PSSAs is introduced in accordance with translatory FHMs-PSSAs, rotary FHMs-PSSAs, and multi-DOF FHMs-PSSAs. Additionally, the developed analysis methods and design schemes to improve the performance are introduced, including theoretical analysis methods, consistency scheme of forward and reverse performance, suppression scheme of the backward motion, and improvement scheme of positioning accuracy. The significance of this work can be regarded as a further supplement to the previous review articles on the PSSAs, which will provide a reference and guidance for the future development of FHMs-PSSAs.

Spinning rigid bodies driven by orbital forcing: the role of dry friction

A "circular orbital forcing" makes a chosen point on a rigid body follow a circular motion while the body spins freely around that point. We investigate this problem for the planar motion of a body subject to dry friction. We focus on the effect called reverse rotation (RR), where spinning and orbital rotations are antiparallel. Similar reverse dynamics include the rotations of Venus and Uranus, journal machinery bearings, tissue production reactors, and chiral active particles. Due to dissipation, RRs are possible only as a transient. Here the transient or flip time $t_\textrm{f}$ depends on the circular driving frequency $\omega$, unlike the viscous case previously studied. We find $t_\textrm{f}\sim\omega^{\gamma-1}\mu^{-\gamma/2}$, where $\mu$ is the friction coefficient and $\gamma=0$ ($\gamma=2$) for low (high) $\omega$. Whether RRs really occur depends on the initial conditions as well as on $\mu$ and $H$, a geometrical parameter. The critical $H_\textrm{c}(\mu)$ where RRs become possible follows a $q$-exponential with $q\simeq1.9$, a more restrictive RR scenario than in the wet case. We use animations to visualize the different dynamical regimes that emerge from the highly nonlinear dissipation mechanism of dry friction. Our results are valid across multiple investigated rigid body shapes.

Motion analysis of screw drive in-pipe cleaning robot

In-pipe cleaning robots often need to carry cleaning tools, and their tails are connected with cables such as water pipes and air pipes. Especially when cleaning vertical straight pipes and curved pipes, a greater traction is required. Therefore, a new type of screw drive in-pipe cleaning robot was designed in this paper. The robot solves the problems of small traction, complex structure, and unstable motion of the in-pipe cleaning robot. The kinematics modeling was carried out on the screw drive in-pipe cleaning robot’s screw module for generating traction, and the force analysis was performed on this basis. The function model of the torque, air pressure, and traction of the screw module was established, which was verified by the simulation and experiment. The results show that the screw in-pipe cleaning robot has a large traction, stable operation, and can be well adapted to the vertical straight pipes and curved pipes.

Mechanistic Modeling of Longitudinal Shape Changes: Equations of Motion and Inverse Problems.

This paper examines a longitudinal shape evolution model in which a three-dimensional volume progresses through a family of elastic equilibria in response to the time-derivative of an internal force, or yank, with an additional regularization to ensure diffeomorphic transformations. We consider two different models of yank and address the long time existence and uniqueness of solutions for the equations of motion in both models. In addition, we derive sufficient conditions for the existence of an optimal yank that best describes the change from an observed initial volume to an observed volume at a later time. The main motivation for this work is the understanding of processes such as growth and atrophy in anatomical structures, where the yank could be roughly interpreted as a metabolic event triggering morphological changes. We provide preliminary results on simple examples to illustrate, under this model, the retrievability of some attributes of such events.

Nonintegrability of the Problem of the Motion of an Ellipsoidal Body with a Fixed Point in a Flow of Particles

The problem of the motion, in the free molecular flow of particles, of a rigid body with a fixed point bounded by the surface of an ellipsoid of revolution is considered. This problem is similar in many aspects to the classical problem of the motion of a heavy rigid body about a fixed point. In particular, this problem possesses the integrable cases corresponding to the classical Euler – Poinsot, Lagrange and Hess cases of integrability of the equations of motion of a heavy rigid body with a fixed point. A natural question arises about the existence of analogues of other integrable cases that exist in the problem of motion of a heavy rigid body with a fixed point (Kovalevskaya case, Goryachev – Chaplygin case, etc) for the system considered. Using the standard Euler angles as generalized coordinates, the Hamiltonian function of the system is derived. Equations of motion of the body in the flow of particles are presented in Hamiltonian form. Using the theorem on the Liouville-type nonintegrability of Hamiltonian systems near elliptic equilibrium positions, which has been proved by V. V. Kozlov, necessary conditions for the existence in the problem under consideration of an additional analytic first integral independent of the energy integral are presented. We have proved that the necessary conditions obtained are not fulfilled for a rigid body with a mass distribution corresponding to the classical Kovalevskaya integrable case in the problem of the motion of a heavy rigid body with a fixed point. Thus, we can conclude that this system does not possess an integrable case similar to the Kovalevskaya integrable case in the problem of the motion of a heavy rigid body with a fixed point.

Bionic Perception Method of Navel Orange Plucking Position Based on Fmincon and PD Angle Control

In this paper, a bionic perception method of navel orange plucking position based on Fmincon and Proportional Differential (PD) angle control is proposed to solve the problems of wind disturbance and green branches in dynamic unstructured environment. Different from these algorithms that limited to two-dimensional images, this method realizes picking position perception in three-dimensional. Meanwhile, the perception method and the picking robot control algorithm are achieved simultaneously. Firstly, an optimal solution model of the global target rotation angle of the control system based on Fmincon is established to solve the angle optimization problem of robot target approach motion. Secondly, a bionic perception system of plucking position based on PD angle control is constructed to solve specific perception problems. Finally, a joint simulation platform for picking robots based on Solidworks, Adams, and Simulink is given; the validity and accuracy of the algorithm were verified. The experimental results show that the picking accuracy rate is 95%, the angle error of each mechanism and the displacement error are less than 0.5 degrees and 10mm, respectively. The total time from the optimized angle calculation to the system's stability is only about 0.33s. This method is suitable for the rapid perception of plucking position and active angle control of picking robots under dynamic unstructured environment.

On a Change of Variables in Lagrange’s Equations

In addition, some methodical examples interesting in theory and applications are considered. In some of them (the equilibrium of a polytropic gas sphere between whose particles the forces of gravitational attraction act and the problem of the planar motion of a charged particle in the dipole force field) Lagrange’s equations are not only covariant, but also possess the invariance property.

Двумерное термокапиллярное движение жидкости в открытом канале

The problem of two-dimensional thermocapillary fluid motion in a flat channel is studied. The temperature in the liquid is distributed according to the quadratic law, which is consistent with the velocity field of the Himentz type. At the bottom of the channel, the temperature depends on the time, which allows you to control the movement inside the layer. The Oberbeck-Boussinesq equations are taken as a mathematical model. The resulting initial - boundary value problem is highly nonlinear and inverse with respect to the pressure gradient along the channel. To solve it, a modified Galerkin method was used, where Legendre polynomials were chosen as the basis functions. The expansion coefficients are functions of time for which a system of nonlinear ODES was obtained. As a result of the application of the Runge-Kutta-Felberg method, a solution was found that, with increasing time, tends to solve a stationary problem if the temperature at the bottom of the channel stabilizes.

On Smooth Planar Curvilinear Motion of Cable-Driven Parallel Robot End-effector*

The paper deals with the problem of smooth motion of the end-effector of an overactuated cable-driven parallel robot. There is observed a way to give planar curvilinear trajectory via Fourie series. The idea of this work is to use special sigmoid function as an argument of function composition to achieve smoothness at the beginning of motion of the end-effector of a cable-driven parallel robot. The developed method makes it possible to reduce the positioning errors of the end-effector when moving along complex trajectories.

A new multimodal planning algorithm based on PRM

The robot motion planning problem has a unique multimodal structure, where the space of feasible configuration consists of intersecting submanifolds. The planning problem of reconfigurable robot leg motions was considered as a multimodal structure composed of intersecting submanifolds in different dimensions. After that, a new multimodal planning algorithm based on PRM was proposed. Simulation results showed that the new algorithm had a shorter running time than PRM in different modes.

The potential of the shadow measure

It is well known that given two probability measures μ and ν on R in convex order there exists a discrete-time martingale with these marginals. Several solutions are known (for example from the literature on the Skorokhod embedding problem in Brownian motion). But, if we add a requirement that the martingale should minimise the expected value of some functional of its starting and finishing positions then the problem becomes more difficult. Beiglböck and Juillet (Ann. Probab. 44 (2016) 42–106) introduced the shadow measure which induces a family of martingale couplings, and solves the optimal martingale transport problem for a class of bivariate objective functions. In this article we extend their (existence and uniqueness) results by providing an explicit construction of the shadow measure and, as an application, give a simple proof of its associativity.

Spatial transportation of the beam on a bifilar fastening

The complex problem of the spatial motion of the "trolley-beam" mechanical system is investigated. Three stages are considered: 1) movement of the beam on a bifilar suspension to the movable trolley; 2) movement of the beam after the breakage of one branch of the suspension; 3) movement of the beam after the breakage of the second branch of the suspension. The study was carried out by creating mathematical models for each stage of the system movement and then conducting a numerical experiment using computer algebra. The tension of the ropes is calculated at the first and second stages of the system movement. Their extreme values are determined. The obtained results will be used in the further study of the system to reduce the tension of the rope and oscillation amplitude and to prevent accidents.

Simulation of Design Parameters of a Milking Cup with An Extended Service Life

Abstract Modern milking machines need some additional studies to meet the requirements as to milking equipment. An imperfect design of a teatcup results in an incomplete milking of cows. The availability of devices for milk flow stimulation promotes an increase in a cow milk yielding capacity. But here arises a problem of an un-controlled axial motion of a teatcup on a teat. As a result, a full milkflow is reduced, particularly at the final stages of milking. There is an effect of an increase in an inner diameter of a liner barrel, which causes that teatcups fall down. A scientific problem of the mitigation of some negative developments with the view to improve the efficiency of a teatcup arises. In a teatcup shell a liner is in a detended position during milking and resting periods. Thus, it under constant stretching. It results in a loss of elasticity irrespective of the material, as well as in reduction ofthe period of service maintenance. The use of a device for supporting a liner which is in a stretched state only during the milkflow, will result in an increase of a teatcup efficiency. The suggested automatic pneumatic mechanism releases a liner from the load during the resting period. The dependence of a tension force of a liner from the surface area of an annular membrane has been established. It has been proven that the membrane surface of 0.00065 m2 provides tension for a mechanism performance irrespective of operating vacuum pressure. The regression equation which connects geometrical parameters of an operating system with the efforts directed at the opening of a leading membrane has been received. A suitability of operation of using a pneumatic tightening device has been substantiated. An insignificant axial motion of a liner during a cycle of milking creates a stimulating effect. As a result, a completeness of miliking increases by 3-8%.

Massive Tophaceous Gout at Right Elbow Region in 55 Years Old Male

Gouty arthritis is one of the most common inflammatory joint diseases, characterized by monosodium urate crystals in or around the joints that comes from purine metabolism. Risk factors of gout are age, excessive intake of purine, alcohol, obesity, lack of physical activity, hypertension and heart disease, certain drugs, and impaired kidney function. This case presented a 55-year-old male patient with lumps and pain in the right elbow. Uric acid laboratory test results with a level of 9.20 mg/dL. Surgical excision could be the only solution to solve minimally decreased range of motion and aesthetic problems. Metabolic problems should be considered a priority with the patients who have unilateral joints problems.

Formulating Event-Based Image Reconstruction as a Linear Inverse Problem With Deep Regularization Using Optical Flow.

Event cameras are novel bio-inspired sensors that measure per-pixel brightness differences asynchronously. Recovering brightness from events is appealing since the reconstructed images inherit the high dynamic range (HDR) and high-speed properties of events; hence they can be used in many robotic vision applications and to generate slow-motion HDR videos. However, state-of-the-art methods tackle this problem by training an event-to-image Recurrent Neural Network (RNN), which lacks explainability and is difficult to tune. In this work we show, for the first time, how tackling the combined problem of motion and brightness estimation leads us to formulate event-based image reconstruction as a linear inverse problem that can be solved without training an image reconstruction RNN. Instead, classical and learning-based regularizers are used to solve the problem and remove artifacts from the reconstructed images. The experiments show that the proposed approach generates images with visual quality on par with state-of-the-art methods despite only using data from a short time interval. State-of-the-art results are achieved using an image denoising Convolutional Neural Network (CNN) as the regularization function. The proposed regularized formulation and solvers have a unifying character because they can be applied also to reconstruct brightness from the second derivative. Additionally, the formulation is attractive because it can be naturally combined with super-resolution, motion-segmentation and color demosaicing. Code is available at https://github.com/tub-rip/event_based_image_rec_inverse_problem.