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Journal articles on the topic '3D Rigid Body Motion'
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Zabunov, Svetoslav. "Rigid body motion in stereo 3D simulation." European Journal of Physics 31, no. 6 (2010): 1345–52. http://dx.doi.org/10.1088/0143-0807/31/6/004.
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Chen, Huihong, and Shiming Li. "Simulation of 3D Image Reconstruction in Rigid body Motion." MATEC Web of Conferences 232 (2018): 02002. http://dx.doi.org/10.1051/matecconf/201823202002.
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3D image reconstruction under rigid body motion is affected by rigid body motion and visual displacement factors, which leads to low quality of 3D image reconstruction and more noise, in order to improve the quality of 3D image reconstruction of rigid body motion. A 3D image reconstruction technique is proposed based on corner detection and edge contour feature extraction in this paper. Region scanning and point scanning are combined to scan rigid body moving object image. The wavelet denoising method is used to reduce the noise of the 3D image. The edge contour feature of the image is extracted. The sparse edge pixel fusion method is used to decompose the feature of the 3D image under the rigid body motion. The irregular triangulation method is used to extract and reconstruct the information features of the rigid body 3D images. The reconstructed feature points are accurately calibrated with the corner detection method to realize the effective reconstruction of the 3D images. The simulation results show that the method has good quality, high SNR of output image and high registration rate of feature points of image reconstruction, and proposed method has good performance of 3D image reconstruction.
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Engström, Mathias, Magnus Mårtensson, Enrico Avventi, Ola Norbeck, and Stefan Skare. "Collapsed fat navigators for brain 3D rigid body motion." Magnetic Resonance Imaging 33, no. 8 (2015): 984–91. http://dx.doi.org/10.1016/j.mri.2015.06.014.
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Bras, Sergio, Maziar Izadi, Carlos Silvestre, Amit Sanyal, and Paulo Oliveira. "Nonlinear Observer for 3D Rigid Body Motion Estimation Using Doppler Measurements." IEEE Transactions on Automatic Control 61, no. 11 (2016): 3580–85. http://dx.doi.org/10.1109/tac.2016.2526671.
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Di Puccio, Francesca, and Paola Forte. "Identification of the 3D Vibratory Motion of a Rigid Body by Accelerometer Measurements." Shock and Vibration 11, no. 3-4 (2004): 281–93. http://dx.doi.org/10.1155/2004/372037.
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The identification of the motion of a rigid body by means of linear accelerometers is a problem already investigated by many researchers, but still debated. The optimisation of the number and placement of accelerometers is also another important aspect of the problem. In this study, an experimental procedure is proposed and applied to identify the rigid-body vibratory motion of the steering wheel of a sporting car, by means of six linear accelerometers. Some numerical simulations for investigating possible errors are also presented.
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Yu, Ying, and Ming Wu. "Rigid-Body Contact Using Finite Particle Method." Advanced Materials Research 684 (April 2013): 130–33. http://dx.doi.org/10.4028/www.scientific.net/amr.684.130.
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Using the recently proposed Finite Particle Method (FPM), this paper presents the rigid-body contact simulation of 3D structures. The FPM models the space truss with finite particles. Following Newton's second law, every particle is in a permanent dynamic equilibrium. Fictitious motion procedures are developed in the particle internal force calculation to handle the geometric nonlinearity without iterative correction. Contact model and corresponding algorithm are developed based on the FPM. A numerical example is presented to demonstrate the capability of the FPM for analyzing rigid-body contact problems.
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SHAMOLIN, MAXIM V. "VARIETY OF THE CASES OF INTEGRABILITY IN DYNAMICS OF A SYMMETRIC 2D-, 3D- AND 4D-RIGID BODY IN A NONCONSERVATIVE FIELD." International Journal of Structural Stability and Dynamics 13, no. 07 (2013): 1340011. http://dx.doi.org/10.1142/s0219455413400117.
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A vast number of papers are devoted to studying the complete integrability of equations of four-dimensional rigid-body motion. Although in studying low-dimensional equations of motion of quite concrete (two- and three-dimensional) rigid bodies in a nonconservative force field, the author arrived at the idea of generalizing the equations to the case of a four-dimensional rigid body in an analogous nonconservative force field. As a result of such a generalization, the author obtained the variety of cases of integrability in the problem of body motion in a resisting medium that fills the four-dimensional space in the presence of a certain tracing force that allows one to reduce the order of the general system of dynamical equations of motion in a methodical way.
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Welch, Edward Brian, Armando Manduca, Roger C. Grimm, Heidi A. Ward, and Clifford R. Jack Jr. "Spherical navigator echoes for full 3D rigid body motion measurement in MRI." Magnetic Resonance in Medicine 47, no. 1 (2001): 32–41. http://dx.doi.org/10.1002/mrm.10012.
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Lv, Wen Jun, and Xin Sheng Ge. "Energy-Based Attitude Control of Spherical Pendulum." Applied Mechanics and Materials 143-144 (December 2011): 355–59. http://dx.doi.org/10.4028/www.scientific.net/amm.143-144.355.
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In this paper, we study the attitude control problems based on model of spherical pendulum. Three degrees of freedom pendulum (3D pendulum) is a rigid body supported by a frictionless pivot. According to relative position of the center of mass and the fixed pivot without friction, the 3D rigid pendulum can be divided into two balanced attitudes, Hanging equilibrium and inverted equilibrium. For the axisymmetric 3D rigid pendulum, the axis of symmetry is equivalent to axis of inertia of rigid body, and angular velocity around the axis of symmetry is equal to zero, as a result, the 3D rigid pendulum can be equal to the spherical pendulum. According to the motion attitude of spherical pendulum, one control method based on passive theory is proposed in this paper, Firstly, we use the passive theory to research the equilibrium stability of spherical pendulum. Secondly, passive theory and the Lyapunov function are utilized to deduce the control law .Finally, the spherical pendulum reach asymptotically stable in equilibrium position.
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Lv, Wen Jun, and Xin Sheng Ge. "Energy-Based Inverted Equilibrium of the Axially Symmetric 3D Pendulum." Applied Mechanics and Materials 138-139 (November 2011): 128–33. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.128.
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In this paper, we study the attitude control problems based on model of the 3D axially symmetric rigid pendulum. Three degrees of freedom pendulum (3D pendulum) is a rigid body supported by a frictionless pivot. According to relative position of the center of mass and the fixed pivot without friction, the 3D rigid pendulum can be divided into two balanced attitudes, Hanging equilibrium and inverted equilibrium. When the 3D rigid pendulum in axis symmetric case, the axis of symmetry is equivalent to axis of inertia of rigid body, and angular velocity around the axis of symmetry is constant that not equal to zero, as a result, the 3D rigid pendulum equal to the axisymmetric rigid pendulum. According to the motion attitude of the axially symmetric 3D pendulum, this article proposes a control method based on passivity, By analyzing the dynamic characteristics, and demonstrate the dynamic characteristics to meet the passive condition. Firstly, we use the passivity theory, from total energy of the system, to research the equilibrium stability of the axially symmetric 3D pendulum in the inverted position. Secondly, to utilize the passivity theory and the Lyapunov function that we proposed to deduce the control law based on the energy method, so that the axially symmetric 3D pendulum to reach asymptotically stable in equilibrium position, and the simulation results verify the availability of the method.
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Wu, S., and L. Hong. "Modelling 3D rigid-body object motion and structure estimation with HRR/GMTI measurements." IET Control Theory & Applications 1, no. 4 (2007): 1023–32. http://dx.doi.org/10.1049/iet-cta:20060034.
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Li, Xiuxiu, Yanjuan Liu, Haiyan Jin, Lei Cai, and Jiangbin Zheng. "RGBD Scene Flow Estimation with Global Nonrigid and Local Rigid Assumption." Discrete Dynamics in Nature and Society 2020 (June 29, 2020): 1–9. http://dx.doi.org/10.1155/2020/8215389.
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RGBD scene flow has attracted increasing attention in the computer vision with the popularity of depth sensor. To estimate the 3D motion of object accurately, a RGBD scene flow estimation method with global nonrigid and local rigid motion assumption is proposed in this paper. Firstly, the preprocessing is implemented, which includes the colour-depth registration and depth image inpainting, to processing holes and noises in the depth image; secondly, the depth image is segmented to obtain different motion regions with different depth values; thirdly, scene flow is estimated based on the global nonrigid and local rigid assumption and spatial-temporal correlation of RGBD information. In the global nonrigid and local rigid assumption, each segmented region is divided into several blocks, and each block has a rigid motion. With this assumption, the interaction of motion from different parts in the same segmented region is avoided, especially the nonrigid object, e.g., a human body. Experiments are implemented on RGBD tracking dataset and deformable 3D reconstruction dataset. The visual comparison shows that the proposed method can distinguish the motion parts from the static parts in the same region better, and the quantitative comparisons proved more accurate scene flow can be obtained.
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Ferdinands, Rene. "Kinetics Analysis of Pelvis, Thorax, and Bowling Arm in Cricket Bowling." Journal of Postgraduate Medicine, Education and Research 49, no. 4 (2015): 159–63. http://dx.doi.org/10.5005/jp-journals-10028-1168.
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ABSTRACT In this study, a three-dimensional (3D) dynamics model of the human body was developed to analyze the motion of fast bowling in cricket. Nine fast bowlers (22.4 ± 3.2 years) were selected from high-level regional cricket to bowl a series of balls at a target placed approximately on a ‘good length’ in line with the wickets, while their bowling actions were captured by a 10-camera 240 Hz motion analysis system (Motion Analysis Corp.). Motion analysis data were obtained from the tracked markers on the bowler strategically placed on the body to define a 3D joint coordinate system for each segment. Two Bertec force plates were used to measure the ground reaction forces. The resulting kinematic and force plate data of the fastest ball were fed into a computer model designed using the Mechanical Systems Pack (Wolfram Research, Inc., V. 5.2), a set of Mathematica packages written for the analysis of spatial rigid body mechanisms, implementing a dynamics formulation with Lagrangian multipliers. The computer model gave a 3D representation of the human body as a system of 15 rigid body segments with mass and inertia properties. Inverse solution dynamics were calculated to generalize certain fundamental aspects of the pelvis, thorax and bowling arm during fast bowling. How to cite this article Ferdinands R. Kinetics Analysis of Pelvis, Thorax, and Bowling Arm in Cricket Bowling. J Postgrad Med Edu Res 2015;49(4):159-163.
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Hülsken, Frank, Christian Eckes, Roland Kuck, Jörg Unterberg, and Sophie J�rg. "Modeling and Animating Virtual Humans for Real-Time Applications." International Journal of Virtual Reality 6, no. 4 (2007): 11–20. http://dx.doi.org/10.20870/ijvr.2007.6.4.2704.
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We report on the workflow for the creation of realistic virtual anthropomorphic characters. 3D-models of human heads have been reconstructed from real people by following a structured light approach to 3D-reconstruction. We describe how these high-resolution models have been simplified and articulated with blend shape and mesh skinning techniques to ensure real-time animation. The full-body models have been created manually based on photographs. We present a system for capturing whole body motions, including the fingers, based on an optical motion capture system with 6 DOF rigid bodies and cybergloves. The motion capture data was processed in one system, mapped to a virtual character and visualized in real-time. We developed tools and methods for quick post processing. To demonstrate the viability of our system, we captured a library consisting of more than 90 gestures.
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Wang Jin, Hexianbao, and Li baolin. "The continuous non-rigid 3D body motion recovery algorithm based on the Murkowski distance." Journal of Convergence Information Technology 7, no. 16 (2012): 355–61. http://dx.doi.org/10.4156/jcit.vol7.issue16.43.
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Leine, Remco I., Giuseppe Capobianco, Perry Bartelt, Marc Christen, and Andrin Caviezel. "Stability of rigid body motion through an extended intermediate axis theorem: application to rockfall simulation." Multibody System Dynamics 52, no. 4 (2021): 431–55. http://dx.doi.org/10.1007/s11044-021-09792-y.
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AbstractThe stability properties of a freely rotating rigid body are governed by the intermediate axis theorem, i.e., rotation around the major and minor principal axes is stable whereas rotation around the intermediate axis is unstable. The stability of the principal axes is of importance for the prediction of rockfall. Current numerical schemes for 3D rockfall simulation, however, are not able to correctly represent these stability properties. In this paper an extended intermediate axis theorem is presented, which not only involves the angular momentum equations but also the orientation of the body, and we prove the theorem using Lyapunov’s direct method. Based on the stability proof, we present a novel scheme which respects the stability properties of a freely rotating body and which can be incorporated in numerical schemes for the simulation of rigid bodies with frictional unilateral constraints. In particular, we show how this scheme is incorporated in an existing 3D rockfall simulation code. Simulations results reveal that the stability properties of rotating rocks play an essential role in the run-out length and lateral spreading of rocks.
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Zhou-Bowers, S., and D. C. Rizos. "B-Spline Impulse Response Functions of Rigid Bodies for Fluid-Structure Interaction Analysis." Advances in Civil Engineering 2018 (October 11, 2018): 1–10. http://dx.doi.org/10.1155/2018/9760361.
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Reduced 3D dynamic fluid-structure interaction (FSI) models are proposed in this paper based on a direct time-domain B-spline boundary element method (BEM). These models are used to simulate the motion of rigid bodies in infinite or semi-infinite fluid media in real, or near real, time. B-spline impulse response function (BIRF) techniques are used within the BEM framework to compute the response of the hydrodynamic system to transient forces. Higher-order spatial and temporal discretization is used in developing the kinematic FSI model of rigid bodies and computing its BIRFs. Hydrodynamic effects on the massless rigid body generated by an arbitrary transient acceleration of the body are computed by a mere superposition of BIRFs. Finally, the dynamic models of rigid bodies including inertia effects are generated by introducing the kinematic interaction model to the governing equation of motion and solve for the response in a time-marching scheme. Verification examples are presented and demonstrate the stability, accuracy, and efficiency of the proposed technique.
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POSIADALA, BOGDAN, PAWEL WARYS, DAWID CEKUS, and MATEUSZ TOMALA. "THE DYNAMICS OF THE FOREST CRANE DURING THE LOAD CARRYING." International Journal of Structural Stability and Dynamics 13, no. 07 (2013): 1340013. http://dx.doi.org/10.1142/s0219455413400130.
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In this paper, the theoretical and calculation model of the forest crane and the lifted load is presented. The model enables the simulation of the motion of the load carried by a forest crane while taking into account the elastic deformations of the boom. The lifted load has been modeled as a 3D rigid body. The application of such a load model enables the simplification and enhancement of the calculation algorithm. The equations describing the coupled motion of the system load and machine elements are presented. The kinematic model enables the analysis of the basic motion of the load as a response of the system to operational control of the forest crane. In order to determine the motion parameters it was assumed that all system elements are rigid. The lifted load is also treated as a rigid body and its motion is the result of the movement of the load suspension point and the dynamic interactions generated during the motion of the system. The presented sample results from the numerical calculations were obtained from the Matlab system. The initial problem has been solved by the Runge–Kutta method. The numerical program has been developed on the basis of the presented model which allows analyzing the motion of load arising from crane operating mechanisms.
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Aly, Abdelraheem M., Mitsuteru Asai, and Ali J. Chamkha. "Analysis of unsteady mixed convection in lid-driven cavity included circular cylinders motion using an incompressible smoothed particle hydrodynamics method." International Journal of Numerical Methods for Heat & Fluid Flow 25, no. 8 (2015): 2000–2021. http://dx.doi.org/10.1108/hff-10-2014-0305.
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Purpose – The purpose of this paper is to model mixed convection in a square cavity included circular cylinders motion using an incompressible smoothed particle hydrodynamics (ISPH) technique. Design/methodology/approach – The problem is solved numerically by using the ISPH method. Findings – The SPH tool shows robust performance to simulate the rigid body motion in the mixed convective flow with heat transfer, and it may apply easily to complicated problems in 2D and 3D problem without difficulties. Originality/value – The application of the SPH method to mixed convective flow with heat transfer and its potential application easily to complicated 3D problems is original.
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Page, A., P. Candelas, F. Belmar, and H. De Rosario. "Analysis of 3D rigid-body motion using photogrammetry: A simple model based on a mechanical analogy." American Journal of Physics 75, no. 1 (2007): 56–61. http://dx.doi.org/10.1119/1.2359002.
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Costa, Andreu F., Daniel W. Petrie, Yi-Fen Yen, and Maria Drangova. "Using the axis of rotation of polar navigator echoes to rapidly measure 3D rigid-body motion." Magnetic Resonance in Medicine 53, no. 1 (2004): 150–58. http://dx.doi.org/10.1002/mrm.20306.
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Chen, Peng-zhan, Jie Li, Man Luo, and Nian-hua Zhu. "Real-Time Human Motion Capture Driven by a Wireless Sensor Network." International Journal of Computer Games Technology 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/695874.
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The motion of a real object model is reconstructed through measurements of the position, direction, and angle of moving objects in 3D space in a process called “motion capture.” With the development of inertial sensing technology, motion capture systems that are based on inertial sensing have become a research hot spot. However, the solution of motion attitude remains a challenge that restricts the rapid development of motion capture systems. In this study, a human motion capture system based on inertial sensors is developed, and the real-time movement of a human model controlled by real people’s movement is achieved. According to the features of the system of human motion capture and reappearance, a hierarchical modeling approach based on a 3D human body model is proposed. The method collects articular movement data on the basis of rigid body dynamics through a miniature sensor network, controls the human skeleton model, and reproduces human posture according to the features of human articular movement. Finally, the feasibility of the system is validated by testing of system properties via capture of continuous dynamic movement. Experiment results show that the scheme utilizes a real-time sensor network-driven human skeleton model to achieve the accurate reproduction of human motion state. The system also has good application value.
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Kermarrec, Gaël, Niklas Schild, and Jan Hartmann. "Fitting Terrestrial Laser Scanner Point Clouds with T-Splines: Local Refinement Strategy for Rigid Body Motion." Remote Sensing 13, no. 13 (2021): 2494. http://dx.doi.org/10.3390/rs13132494.
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T-splines have recently been introduced to represent objects of arbitrary shapes using a smaller number of control points than the conventional non-uniform rational B-splines (NURBS) or B-spline representatizons in computer-aided design, computer graphics and reverse engineering. They are flexible in representing complex surface shapes and economic in terms of parameters as they enable local refinement. This property is a great advantage when dense, scattered and noisy point clouds are approximated using least squares fitting, such as those from a terrestrial laser scanner (TLS). Unfortunately, when it comes to assessing the goodness of fit of the surface approximation with a real dataset, only a noisy point cloud can be approximated: (i) a low root mean squared error (RMSE) can be linked with an overfitting, i.e., a fitting of the noise, and should be correspondingly avoided, and (ii) a high RMSE is synonymous with a lack of details. To address the challenge of judging the approximation, the reference surface should be entirely known: this can be solved by printing a mathematically defined T-splines reference surface in three dimensions (3D) and modeling the artefacts induced by the 3D printing. Once scanned under different configurations, it is possible to assess the goodness of fit of the approximation for a noisy and potentially gappy point cloud and compare it with the traditional but less flexible NURBS. The advantages of T-splines local refinement open the door for further applications within a geodetic context such as rigorous statistical testing of deformation. Two different scans from a slightly deformed object were approximated; we found that more than 40% of the computational time could be saved without affecting the goodness of fit of the surface approximation by using the same mesh for the two epochs.
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Wang, Yi-Ren, and Ko-En Hung. "Damping Effect of Pendulum Tuned Mass Damper on Vibration of Two-Dimensional Rigid Body." International Journal of Structural Stability and Dynamics 15, no. 02 (2015): 1450041. http://dx.doi.org/10.1142/s0219455414500412.
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This study investigated the effect of a pendulum tuned mass damper (PTMD) on the vibration of a slender two-dimensional (2D) rigid body with 1:2 internal resonance. Focus is placed on the damping effect of various parameters of the PTMD on preventing the internal resonance of the system. The instruments used include fixed points plots, time response and Poincaré maps, which were compared for confirmation of accuracy. The Lagrange's equation is employed to derive the equations of motion for the system. The method of multiple scales (MOMS) is applied to analyzing this nonlinear vibration model. The internal resonance conditions of the rigid body in vibration are obtained by the eigen-analysis. Moreover, a 3D internal resonance contour plot (3D-IRCP) aided by various amplitude analysis tables is proposed for identification of the parameter combinations of the PTMD for preventing internal resonance. This approach enables the designers to evaluate the effectiveness of various parameter combinations of the PTMD prior to the design process. The present study indicates that without changing the main configuration, the vibration amplitudes in the main body can be greatly reduced under certain parameter combinations of the PTMD.
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Qiang, Yang, Geng Hua Wang, Bian Ji, and Luo Hao. "Rigid-Flexibility Modeling and Simulations of Lower-Mobility Parallel Mechanisms." Advanced Materials Research 681 (April 2013): 224–28. http://dx.doi.org/10.4028/www.scientific.net/amr.681.224.
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Considering the flexibility performance of lightweight slender axle in Delta parallel mechanisms, the effects of the elastic deformation on the kinematic accuracy of the mechanism are calculated based on the virtual prototype technology. Firstly, the 3D model of the mechanism is built via ADAMS software. Secondly, the geometric model of the driving rod is imported into ANSYS software to get meshed and generate the modal neutral files. Then, getting back to ADAMS, the original rigid component is replaced with the flexible body which constraint and driving is added to lately. At last, the rigid-flexibility hybrid model of the mechanism is built. Each frequency and vibration mode of the flexible body is calculated, using the simulation capabilities of the software. Furthermore, changes in motion accuracy of the mechanism under the effect of the force-elastic coupling are analyzed comparatively.
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Meyer, Georg, Emma Clarke, and Tony Robotham. "Multisensory interactions in the automatic control of postural sway." Seeing and Perceiving 25 (2012): 77. http://dx.doi.org/10.1163/187847612x646983.
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Visual motion signals are an important source of self-motion information that are used in postural control. Bronstein and Buckwell (Exp. Brain Res. 113, 243–248, 1997) showed that postural reactions to visual motion are not rigid responses to optokinetic stimulation but specific responses appropriate for stabilising posture in natural circumstances: body sway, for instance, was abolished when participants fixated a static object in front of a laterally moving background, which in itself induced sway. We test whether haptic and auditory as well as visual fixation points reduce body sway induced by a background that either moved left/right or forward/back on a large (3 × 7 m) 3D visual display. 10 participants were asked to respond when a fixation target, whichs was presented either on a background or foreground, changed colour. Body sway was measured using a VICON motion tracking system. We tested three conditions that replicated Bronstein and Buckwell’s original study and show that body sway, induced by lateral motion of the background is abolished when participant fixate on a (virtual) foreground object. We extended their study by showing that 3D motion (looming/receding background) has a similar effect to lateral motion and to show that body sway can be effectively reduced by providing either auditory (a loudspeaker emitting a white noise) and haptic (participants lightly touch a tripod with their index finger) cues. Our findings show that postural control draws auditory and haptic as well as visual cues. The findings are relevant to the design of virtual reality systems and provide a method for objective measures of presence in virtual environments.
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Kulikov, G. M., and S. V. Plotnikova. "Advanced formulation for laminated composite shells: 3D stress analysis and rigid-body motions." Composite Structures 95 (January 2013): 236–46. http://dx.doi.org/10.1016/j.compstruct.2012.07.020.
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Buschbeck, Richard P., Seong Dae Yun, and N. Jon Shah. "3D rigid‐body motion information from spherical Lissajous navigators at small k‐space radii: A proof of concept." Magnetic Resonance in Medicine 82, no. 4 (2019): 1462–70. http://dx.doi.org/10.1002/mrm.27796.
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Berman, Sigal, Dario G. Liebermann, and Tamar Flash. "Application of motor algebra to the analysis of human arm movements." Robotica 26, no. 4 (2008): 435–51. http://dx.doi.org/10.1017/s0263574707003979.
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SUMMARYMotor algebra, a 4D degenerate geometric algebra, offers a rigorous yet simple representation of the 3D velocity of a rigid body. Using this representation, we study 3D extended arm pointing and reaching movements. We analyze the choice of arm orientation about the vector connecting the shoulder and the wrist, in cases for which this orientation is not prescribed by the task. Our findings show that the changes in this orientation throughout the movement were very small, possibly indicating an underlying motion planning strategy. We additionally examine the decomposition of movements into submovements and reconstruct the motion by assuming superposition of the velocity profiles of the underlying submovements by analyzing both the translational and rotational components of the 3D spatial velocity. This movement decomposition method reveals a larger number of submovement than is found using previously applied submovement extraction methods that are based only on the analysis of the hand tangential velocity. The reconstructed velocity profiles and final orientations are relatively close to the actual values, indicating that single-axis submovements may be the basic building blocks underlying 3D movement construction.
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Javorova, Juliana, and Anastas Ivanov. "Study of soccer ball flight trajectory." MATEC Web of Conferences 145 (2018): 01002. http://dx.doi.org/10.1051/matecconf/201814501002.
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In this paper the trajectories of a soccer ball for the most important kicks in the football game - a corner kick and a direct free kick are studied. The soccer ball is modelled as an ideal rigid hollow spherical body with six degrees of freedom, which performs a general motion in an immovable air environment with constant parameters. The ball 3D orientation is determined by the three Cardan angles. The aerodynamic forces and moments with which the air environment acts to the ball are taken into account. Two of the most dangerous areas of the football goal are defined. Differential equations which describe the motion of the soccer ball are solved numerically by MatLab-Simulink.
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WEI, GENGSHENG. "A FIXED-MESH METHOD FOR GENERAL MOVING OBJECTS IN FLUID FLOW." Modern Physics Letters B 19, no. 28n29 (2005): 1719–22. http://dx.doi.org/10.1142/s021798490501030x.
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In this work, a fixed-mesh method for general moving objects in fluid flow was developed and implemented into the commercial CFD software FLOW-3D . A general moving object is a rigid body with any type of six-degrees-of-freedom, fixed-point and fixed-axis motion which can be either user-prescribed or dynamically coupled with fluid flow. The method allows multiple general moving objects, and each of them can possess any different type of motion. Area and volume fractions to represent the objects in the fixed-grid are calculated at every time step to describe time-variation of object locations and orientations. Continuity and momentum equations for fluid are modified to account for the effects of object motion on fluid flow. A good agreement is achieved between computational and experimental results in an application to a valve problem.
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Li, Guang, Kai Liu, Wenwen Ding, Fei Cheng, and Boyang Chen. "Key-Skeleton-Pattern Mining on 3D Skeletons Represented by Lie Group for Action Recognition." Mathematical Problems in Engineering 2018 (December 5, 2018): 1–14. http://dx.doi.org/10.1155/2018/7952974.
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The human skeleton can be considered as a tree system of rigid bodies connected by bone joints. In recent researches, substantial progress has been made in both theories and experiments on skeleton-based action recognition. However, it is challenging to accurately represent the skeleton and precisely eliminate noisy skeletons from the action sequence. This paper proposes a novel skeletal representation, which is composed of two subfeatures to recognize human action: static features and dynamic features. First, to avoid scale variations from subject to subject, the orientations of the rigid bodies in a skeleton are employed to capture the scale-invariant spatial information of the skeleton. The static feature of the skeleton is defined as a combination of the orientations. Unlike previous orientation-based representations, the orientation of a rigid body in the skeleton is defined as the rotations between the rigid body and the coordinate axes in three-dimensional space. Each rotation is mapped to the special orthogonal group SO(3). Next, the rigid-body motions between the skeleton and its previous skeletons are utilized to capture the temporal information of the skeleton. The dynamic feature of the skeleton is defined as a combination of the motions. Similarly, the motions are represented as points in the special Euclidean group SE(3). Therefore, the proposed skeleton representation lies in the Lie group (SE(3)×⋯×SE(3), SO(3)×⋯×SO(3)), which is a manifold. Using the proposed representation, an action can be considered as a series of points in this Lie group. Then, to recognize human action more accurately, a new pattern-growth algorithm named MinP-PrefixSpan is proposed to mine the key-skeleton-patterns from the training dataset. Because the algorithm reduces the number of new patterns in each growth step, it is more efficient than the PrefixSpan algorithm. Finally, the key-skeleton-patterns are used to discover the most informative skeleton sequences of each action (skeleton sequence). Our approach achieves accuracies of 94.70%, 98.87%, and 95.01% on three action datasets, outperforming other relative action recognition approaches, including LieNet, Lie group, Grassmann manifold, and Graph-based model.
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Stoykov, S., and S. Margenov. "Nonlinear Vibrations of 3D Laminated Composite Beams." Mathematical Problems in Engineering 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/892782.
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A model for 3D laminated composite beams, that is, beams that can vibrate in space and experience longitudinal and torsional deformations, is derived. The model is based on Timoshenko’s theory for bending and assumes that, under torsion, the cross section rotates as a rigid body but can deform longitudinally due to warping. The warping function, which is essential for correct torsional deformations, is computed preliminarily by the finite element method. Geometrical nonlinearity is taken into account by considering Green’s strain tensor. The equation of motion is derived by the principle of virtual work and discretized by thep-version finite element method. The laminates are assumed to be of orthotropic materials. The influence of the angle of orientation of the laminates on the natural frequencies and on the nonlinear modes of vibration is presented. It is shown that, due to asymmetric laminates, there exist bending-longitudinal and bending-torsional coupling in linear analysis. Dynamic responses in time domain are presented and couplings between transverse displacements and torsion are investigated.
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Bonanzinga, Tommaso, Cecilia Signorelli, Marco Bontempi, et al. "Evaluation of RSA set-up from a clinical biplane fluoroscopy system for 3D joint kinematic analysis." Joints 04, no. 02 (2016): 121–25. http://dx.doi.org/10.11138/jts/2016.4.2.121.
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Purpose: dinamic roentgen stereophotogrammetric analysis (RSA), a technique currently based only on customized radiographic equipment, has been shown to be a very accurate method for detecting threedimensional (3D) joint motion. The aim of the present work was to evaluate the applicability of an innovative RSA set-up for in vivo knee kinematic analysis, using a biplane fluoroscopic image system. To this end, the Authors describe the set-up as well as a possible protocol for clinical knee joint evaluation. The accuracy of the kinematic measurements is assessed. Methods: the Authors evaluated the accuracy of 3D kinematic analysis of the knee in a new RSA set-up, based on a commercial biplane fluoroscopy system integrated into the clinical environment. The study was organized in three main phases: an in vitro test under static conditions, an in vitro test under dynamic conditions reproducing a flexion-extension range of motion (ROM), and an in vivo analysis of the flexionextension ROM. For each test, the following were calculated, as an indication of the tracking accuracy: mean, minimum, maximum values and standard deviation of the error of rigid body fitting. Results: in terms of rigid body fitting, in vivo test errors were found to be 0.10±0.05 mm. Phantom tests in static and kinematic conditions showed precision levels, for translations and rotations, of below 0.1 mm/0.2º and below 0.5 mm/0.3º respectively for all directions. Conclusions: the results of this study suggest that kinematic RSA can be successfully performed using a standard clinical biplane fluoroscopy system for the acquisition of slow movements of the lower limb. Clinical relevance: a kinematic RSA set-up using a clinical biplane fluoroscopy system is potentially applicable and provides a useful method for obtaining better characterization of joint biomechanics.
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Costagli, Mauro, R. Allen Waggoner, Kenichi Ueno, Keiji Tanaka, and Kang Cheng. "Correction of 3D rigid body motion in fMRI time series by independent estimation of rotational and translational effects in k-space." NeuroImage 45, no. 3 (2009): 749–57. http://dx.doi.org/10.1016/j.neuroimage.2008.12.067.
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Kukielka, Leon, Krzysztof Kukielka, Agnieszka Kułakowska, Radoslaw Patyk, Radosław Patyk, and Łukasz Bohdal. "Incremental Modelling and Numerical Solution of the Contact Problem between Movable Elastic and Elastic/Visco-Plastic Bodies and Application in the Technological Processes." Applied Mechanics and Materials 474 (January 2014): 159–64. http://dx.doi.org/10.4028/www.scientific.net/amm.474.159.
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Paper presents the modelling of the contact problem in the technological processes. Technological processes were considered as a geometrical and physical boundary and initial value problem, with unknown boundary conditions in the contact zone. An incremental model of the contact problem between movable rigid or elastic body (tool) and elastic/visco-plastic body (object) in updated Lagrange formulation, for spatial states (3D) was considered. The incremental functional of the total energy and variational, non-linear equation of motion and deformation of object on the typical step time were derived. This equation has been discretized by finite element method, and the system of discrete equations of motion of objects was received. For solution of these equations the explicit or implicit methods was used. The applications were developed in the ANSYS/LS-Dyna system, which makes possible a complex time analysis of the states of displacements, strains and stresses, in the workpieces in technological processes. Application of this method was showed for examples the modelling and the analysis of tensile test [1 and technological processes of metal forming [1-.
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Zhang, He, Shaowei Yang, and Zhengfeng Ma. "Model of the wheel motion state under path constraints based on the Darboux frame in 3D space." Engineering Computations 35, no. 8 (2018): 2883–903. http://dx.doi.org/10.1108/ec-11-2017-0460.
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Purpose Existing three-dimensional (3D) road-surface models use approximation methods such as a set of discrete triangular patches and cannot accurately describe changes in the geometrically designed elements along the road. This paper aims to construct a 3D road-surface model with combinations of geometric design invariants and apply the proposed model to analyse the state of motion of a wheel’s centre. Design/methodology/approach In this paper, the 3D road surface is modelled as a continuous function with combinations of geometric design invariants. By introducing the theories of differential geometries and rigid body dynamics, a wheel-road model wherein a wheel fixed to a Darboux frame moves along a curved road surface is constructed, and the wheel time-dependent properties of the velocity, angular velocity and acceleration at an arbitrary point of the surface are described using road geometry design invariants. Findings This paper adopts the Darboux frame to study the instantaneous spin-rolling motion of a wheel. It is found that the magnitudes of the spin-rolling velocity, the acceleration and the geometric invariants of the road surface, including the geodesic curvature, the normal curvature and the geodesic torsion, determine the instantaneous states of motion of a wheel. Originality/value This work provides a theoretical foundation for future studies of wheel motion states, such as the relationship between road geometry design invariants and driving safety, vehicle lane changing and other vehicle microbehaviours. New insights are gained in the areas of road safety and vehicles incorporating artificial intelligence.
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Hu, Zheng Zheng Hu, Derek Causon, Clive Mingham, and Ling Qian. "NUMERICAL SIMULATION OF WATER IMPACT INVOLVING THREE DIMENSIONAL RIGID BODIES OF ARBITRARY SHAPE." Coastal Engineering Proceedings 1, no. 32 (2011): 14. http://dx.doi.org/10.9753/icce.v32.posters.14.
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As is well known, the design of coastal or offshore structures whether a ship, wave energy device or other fixed or floating structure, needs to consider its operation in a very hostile environment, including heavy storms. For example, an extremely high or steep wave impact on the bow or stern of a moored FPSO may result in a large amount of water on deck. Known as green water, this may cause severe damage to the deck house or other deckside equipment. Thus, there is great need for simulation tools to predict impact loadings and to provide more insight into the physics of local impact phenomena. 
 
 Published research or prediction work on the water impact problem has mostly related to studies in 2D. For example, Greehow& Lin (1983), Greenhow (1987), Zhao & Faltinsen (1993), Mei et al.(1999) have studied the hydrodynamics of rigid bodies entering water both theoretically and experimentally. More recently, a laboratory investigation of the pressure distribution on a free-falling wedge entering water by Yettou et al.(2006 has been compared a numerical and experimental study carried out by Campbell and Weynberg (1980). Water impact and green water loading in 3D has been simulated by Kleefsman et al. (2005) using a VOF method, which for dam break and water entry problems. In this study, we have developed the AMAZON-3D code for studies of water impact problems involving various 3D rigid solid bodies. 
 
 The in-house Cartesian cut cell approach has been used to simulate 3D water impact involving both moving rigid solid bodies and the free surface. The Cartesian cut cell method in the AMAZON-3D code is unrestricted in terms of boundary complexity or range of boundary movement. Solid objects are carved out of a background mesh, leaving a set of irregularly shaped cells aligned with the surface boundary. The advantages of the cut cell approach have been outlined previously by Causon et al. (2000, 2001) and Hu et al.(2009) including its flexibility for dealing with arbitrarily complex geometries and moving bodies. There is no requirement to re-mesh globally or even locally for the case of a moving body. All that is required is to update the cut cell data at the body contour for as long as the body motion continues.
 
 The AMAZON-3D finite volume code solves the incompressible Navier-Stokes equations in both air and water regions simultaneously treating the free surface as a contact surface in the density field that is captured automatically in a manner analogous to shock capturing in compressible flow. A time-accurate artificial compressibility method and high Godunov-type scheme replaces the pressure correction solver used in other methods (see Qian et al. 2006).
 
 We believe that the success of a study of water impact depends ultimately on the problem under consideration and the computer resources available and for each method there is a class of problem for which one method may perform better another. Each method has its own advantages and disadvantages and it is not possible to assert conclusively that one method is uniformly superior. However, we believe we can demonstrate that our method can be used successfully to study real local impact phenomena including the egress of an arbitrary rigid body from air to water or vice versa, the splash zone and entrapment of one fluid into the other. The code has been validated by recourse to a number of test cases including a cone undergoing forced oscillations and water impact of a rigid wedge with constant entry velocity where data and/or analytical results are available for comparison purposes. A range of results including the free surface elevation and force calculations will be presented for the water impact of various 3D rigid bodies.
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Persson, A., L. Larsson, and C. Finnsgård. "An Improved Procedure for Strongly Coupled Prediction of Sailing Yacht Performance." Journal of Sailing Technology 6, no. 01 (2021): 133–50. http://dx.doi.org/10.5957/jst/2021.6.1.133.
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Abstract In this paper, an improved procedure for strongly coupled prediction of sailing yacht performance is developed. The procedure uses 3D RANS CFD to compute the hydrodynamic forces. When coupled to a rigid body motion solver and a sail force model, along with a rudder control algorithm, this allows sailing yacht performance to be predicted within CFD software. The procedure provides improved convergence when compared to a previously published method. The grid motion scheme, partially using overset grid techniques, means that correct alignment between the free surface and the background grid is ensured even at large heel angles. The capabilities are demonstrated with performance predictions for the SYRF 14 m yacht, at one true wind speed, over a range of true wind angles, with up- and downwind sailsets. The results are compared to predictions from the ORC-VPP for a yacht with similar main particulars.
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Impelluso, Thomas J. "The moving frame method in dynamics: Reforming a curriculum and assessment." International Journal of Mechanical Engineering Education 46, no. 2 (2017): 158–91. http://dx.doi.org/10.1177/0306419017730633.
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Rigid body dynamics, a gateway course to the mechanical engineering major (and related majors), focuses on a view of motion that is not commensurate with the contemporary age in which mobile devices have on-board inertial firmware. The traditional approach to this topic deploys a mathematical notation, and associated algebra, that inordinately privileges the inertial frames and 2D motion. This limits the study of machines to two-dimensional problems, lends an appearance of whimsy to solutions that obfuscates the theory of motion. We propose a new mathematical approach to dynamics to reinvigorate the discipline and motivate students. The new approach uses modern mathematical tools which have been distilled to tractability: Lie Group Theory, Cartan’s Moving Frames and a new compact notation from Geometrical Physics. The reconstructed course abandons the cross product—a toxic algebraic operation due to its failure to adhere to associativity. We minimize the use of vectors and replace them with rotation matrices. Sophomores learn to solve 3D Dynamics problems with as much ease as solving 2D problems. Typical problems include the precession of tops, gyroscopes, inertial devices to prevent ship roll at sea, and 3D robot and crane kinetics. A critical aspect of this new method is the consistency: the notation is the same for 3D and 2D problems, from advanced robotics to introductory dynamics, students learn the name notational method. The first objective of this paper presents the new mathematical approach to rigid body dynamics—it amounts to an introductory, yet simplified, lecture on a new method. The second objective presents assessment over a three-year period. In the first year, we taught using the old 2D vector-based approach. In the second year, we transitioned to the new method and compared student perceptions in the first two years. In the third year, the course was refined. The goal of this effort is to retain students in mechanical engineering by offering them a new view of the discipline, rather than simple pedagogical course interventions such as e-learning or flipped classrooms. The course content is delivered using the emerging visualization technology: WebGL. WebGL represents the future of the 3D web. It requires no downloads and no plugins. Students are directed to a web site where all images for the lectures are 3D and interactive. The animations run on cell phones, laptops and other mobile devices. It is the contention of this paper that modernizing the math will do more to reduce attrition than learning interventions. This new approach reduces conceptual difficulties that accompany 2D restrictions. It opens many questions on how students perceive 3D space and invites research into how exploiting more modern mathematical math may improve learning.
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Zwölfer, Andreas, and Johannes Gerstmayr. "A concise nodal-based derivation of the floating frame of reference formulation for displacement-based solid finite elements." Multibody System Dynamics 49, no. 3 (2019): 291–313. http://dx.doi.org/10.1007/s11044-019-09716-x.
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AbstractThe Floating Frame of Reference Formulation (FFRF) is one of the most widely used methods to analyze flexible multibody systems subjected to large rigid-body motion but small strains and deformations. The FFRF is conventionally derived via a continuum mechanics approach. This tedious and circuitous approach, which still attracts attention among researchers, yields so-called inertia shape integrals. These unhandy volume integrals, arising in the FFRF mass matrix and quadratic velocity vector, depend not only on the degrees of freedom, but also on the finite element shape functions. That is why conventional computer implementations of the FFRF are laborious and error prone; they require access to the algorithmic level of the underlying finite element code or are restricted to a lumped mass approximation. This contribution presents a nodal-based treatment of the FFRF to bypass these integrals. Each flexible body is considered in its spatially discretized state ab initio, wherefore the integrals are replaced by multiplications by a constant finite element mass matrix. Besides that, this approach leads to a simpler and concise but rigorous derivation of the equations of motion. The steps to obtain the inertia-integral-free equations of motion (in 2D and 3D spaces) are presented in a clear and comprehensive way; the final result provides ready-to-implement equations of motion without a lumped mass approximation, in contrast to the conventional formulation.
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Serrien, Ben, Todd Pataky, Jean-Pierre Baeyens, and Erik Cattrysse. "Bayesian vs. least-squares inverse kinematics: Simulation experiments with models of 3D rigid body motion and 2D models including soft-tissue artefacts." Journal of Biomechanics 109 (August 2020): 109902. http://dx.doi.org/10.1016/j.jbiomech.2020.109902.
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Ko, Chun-Hsu, and Jein-Shan Chen. "Optimal Grasping Manipulation for Multifingered Robots Using Semismooth Newton Method." Mathematical Problems in Engineering 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/681710.
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Multifingered robots play an important role in manipulation applications. They can grasp various shaped objects to perform point-to-point movement. It is important to plan the motion path of the object and appropriately control the grasping forces for multifingered robot manipulation. In this paper, we perform the optimal grasping control to find both optimal motion path of the object and minimum grasping forces in the manipulation. The rigid body dynamics of the object and the grasping forces subjected to the second-order cone (SOC) constraints are considered in optimal control problem. The minimum principle is applied to obtain the system equalities and the SOC complementarity problems. The SOC complementarity problems are further recast as the equations with the Fischer-Burmeister (FB) function. Since the FB function is semismooth, the semismooth Newton method with the generalized Jacobian of FB function is used to solve the nonlinear equations. The 2D and 3D simulations of grasping manipulation are performed to demonstrate the effectiveness of the proposed approach.
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Huang, Xin, and Lei Gao. "Reconstructing Three-Dimensional Human Poses: A Combined Approach of Iterative Calculation on Skeleton Model and Conformal Geometric Algebra." Symmetry 11, no. 3 (2019): 301. http://dx.doi.org/10.3390/sym11030301.
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Reconstructing three-dimensional (3D) human poses is an essential step in human bodyanimation. The purpose of this paper is to fill the gap in virtual reality research by reconstructingpostures in a high-precision human model. This paper presents a new approach for 3D human posereconstruction based on the iterative calculation of a skeleton model and conformal geometric algebra,captured by a monocular camera. By introducing the strip information of clothes and prior data ofdifferent human limbs, the location of joint points on the human body will not be affected by theocclusion problem. We then calculate the 3D coordinates of joint points based on the proposed methodof the iterative calculation of the skeleton model, which can solve the high-cost problem caused by theneed for multiple cameras or a depth camera. Subsequently, we utilize high-performance conformalgeometric algebra (CGA) in relation to rotation transformations in order to improve the adjustmentof the postures of the human limbs. Finally, realistic 3D human poses are reconstructed—specifically,the motion of the human limbs—using a rigid transformation of CGA and a smooth connection ofthe limb parts based on a high-precision model. Compared with the existing methods, the proposedapproach can obtain satisfactory and realistic 3D human pose estimation results using grid models.
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Guibas, Leonidas J., Dan Halperin, Hirohisa Hirukawa, Jean-Claude Latombe, and Randall H. Wilson. "Polyhedral Assembly Partitioning Using Maximally Covered Cells in Arrangements of Convex Polytopes." International Journal of Computational Geometry & Applications 08, no. 02 (1998): 179–99. http://dx.doi.org/10.1142/s0218195998000102.
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We study the following problem: Given a collection A of polyhedral parts in 3D, determine whether there exists a subset S of the parts that can be moved as a rigid body by infinitesimal translation and rotation, without colliding with the rest of the parts, A\S. A negative result implies that the object whose constituent parts are the collection A cannot be taken apart with two hands. A positive result, together with the list of movable parts in S and a direction of motion for S, can be used by an assembly sequence planner (it does not, however, give the complete specification of an assembly operation). This problem can be transformed into that of traversing an arrangement of convex polytopes in the space of directions of rigid motions. We identify a special type of cells in that arrangement, which we call the maximally covered cells, and we show that it suffices for the problem at hand to consider a representative point in each of these special cells rather than to compute the entire arrangement. Using this observation, we devise an algorithm which is complete (in the sense that it is guaranteed to find a solution if one exists), simple, and improves significantly over the best previously known solutions. We describe an implementation of our algorithm and report experimental results obtained with this implementation.
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Di Gregorio, Raffaele, Mattia Cattai, and Henrique Simas. "Performance-Based Design of the CRS-RRC Schoenflies-Motion Generator." Robotics 7, no. 3 (2018): 55. http://dx.doi.org/10.3390/robotics7030055.
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Rigid-body displacements obtained by combining spatial translations and rotations around axes whose direction is fixed in the space are named Shoenflies’ motions. They constitute a 4-dimensional (4-D) subgroup, named Shoenflies’ subgroup, of the 6-D displacement group. Since the set of rotation-axis’ directions is a bi-dimensional space, the set of Shoenflies’ subgroups is a bi-dimensional space, too. Many industrial manipulations (e.g., pick-and-place on a conveyor belt) require displacements that belong to only one Schoenflies’ subgroup and can be accomplished by particular 4-degrees-of-freedom (4-DOF) manipulators (Shoenflies-motion generators (SMGs)). The first author has recently proposed a novel parallel SMG of type CRS-RRC. Such SMG features a single-loop architecture with actuators on the base and a simple decoupled kinematics. Here, firstly, an organic review of the previous results on this SMG is presented; then, its design is addressed by considering its kinetostatic performances. The adopted design procedure optimizes two objective functions, one (global conditioning index (GCI)) that measures the global performance and the other (CImin) that evaluates the worst local performance in the useful workspace. The results of this optimization procedure are the geometric parameters’ values that make the studied SMG have performances comparable with those of commercial SMGs. In addition, a realistic 3D model that solves all the manufacturing doubts with simple and cheap solutions is presented.
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Kukielka, Leon, Michal Szczesniak, Radoslaw Patyk, et al. "Analysis of the States of Deformation and Stress in the Surface Layer of the Product after the Burnishing Cold Rolling Operation." Materials Science Forum 862 (August 2016): 278–87. http://dx.doi.org/10.4028/www.scientific.net/msf.862.278.
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The article presents the results of computer modelling and numerical simulations the deformation and stresses occurring in the surface layer of the product after the burnishing cold rolling operation. Technological processes were considered as a geometrical and physical boundary and initial value problem, with unknown boundary conditions in the contact zone. An incremental model of the contact problem between movable rigid or elastic body (tool) and elastic/visco-plastic body (object) in updated Lagrange formulation, for spatial states (3D) was considered. The incremental functional of the total energy and variational, non-linear equation of motion and deformation of object on the typical step time were derived. This equation has been discretized by finite element method, and the system of discrete equations of motion of objects was received. For solution of these equations the explicit methods was used. The applications were developed in the ANSYS/LS-Dyna system, which makes possible a complex time analysis of the states of displacements, strains and stresses, in the workpieces in fabrication processes. Application of this method was showed for examples the modelling and the analysis of the asperities with apex angles θ = 85°, 120° and 156°. The Bielajew point using finite elements methodology was indicated. The simulation results were verified experimentally.
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Kihonge, John N., Judy M. Vance, and Pierre M. Larochelle. "Spatial Mechanism Design in Virtual Reality With Networking." Journal of Mechanical Design 124, no. 3 (2002): 435–40. http://dx.doi.org/10.1115/1.1481363.
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Mechanisms are used in many devices to move a rigid body through a finite sequence of prescribed locations. The most commonly used mechanisms are four-bar planar mechanisms that move an object in one plane in space. Spatial mechanisms allow motion in three-dimensions (3D), however, to date they are rarely implemented in industry in great part due to the inherent visualization and design challenges involved. Nevertheless, they do provide promise as a practical solution to spatial motion generation and therefore remain an active area of research. Spatial 4C mechanisms are two degree-of-freedom kinematic closed-chains consisting of four rigid links simply connected in series by cylindrical (C) joints. A cylindrical joint is a two degree-of-freedom joint, which allows translation and rotation about a line in space. This paper describes a synthesis process for the design of 4C spatial mechanisms in a virtual environment. Virtual reality allows the user to view and interact with digital models in a more intuitive way than using the traditional human-computer interface (HCI). The software developed as part of this research also allows multiple users to network and share the designed mechanism. Networking tools have the potential to greatly enhance communication between members of the design team at different industrial sites and therefore reduce design costs. This software presents the first effort to provide a three-dimensional digital design environment for the design of spatial 4C mechanisms.
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Hernando-García, Jorge, Jose Luis García-Caraballo, Víctor Ruiz-Díez, and Jose Luis Sánchez-Rojas. "Motion of a Legged Bidirectional Miniature Piezoelectric Robot Based on Traveling Wave Generation." Micromachines 11, no. 3 (2020): 321. http://dx.doi.org/10.3390/mi11030321.
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This article reports on the locomotion performance of a miniature robot that features 3D-printed rigid legs driven by linear traveling waves (TWs). The robot structure was a millimeter-sized rectangular glass plate with two piezoelectric patches attached, which allowed for traveling wave generation at a frequency between the resonant frequencies of two contiguous flexural modes. As a first goal, the location and size of the piezoelectric patches were calculated to maximize the structural displacement while preserving a standing wave ratio close to 1 (cancellation of wave reflections from the boundaries). The design guidelines were supported by an analytical 1D model of the structure and could be related to the second derivative of the modal shapes without the need to rely on more complex numerical simulations. Additionally, legs were bonded to the glass plate to facilitate the locomotion of the structure; these were fabricated using 3D stereolithography printing, with a range of lengths from 0.5 mm to 1.5 mm. The optimal location of the legs was deduced from the profile of the traveling wave envelope. As a result of integrating both the optimal patch length and the legs, the speed of the robot reached as high as 100 mm/s, equivalent to 5 body lengths per second (BL/s), at a voltage of 65 Vpp and a frequency of 168 kHz. The blocking force was also measured and results showed the expected increase with the mass loading. Furthermore, the robot could carry a load that was 40 times its weight, opening the potential for an autonomous version with power and circuits on board for communication, control, sensing, or other applications.
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Kukielka, Krzysztof, Leon Kukielka, Łukasz Bohdal, Agnieszka Kułakowska, Leszek Malag, and Radoslaw Patyk. "3D Numerical Analysis the State of Elastic/Visco-Plastic Strain in the External Round Thread Rolled on Cold." Applied Mechanics and Materials 474 (January 2014): 436–41. http://dx.doi.org/10.4028/www.scientific.net/amm.474.436.
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This work describes the thread rolling as a real object and its physical and mathematical modelling. An incremental modelling and numerical solution of the contact problem between movable elastic or rigid tool and elastic/visco-plastic bodies developed in [ is adopted to the numerical simulation of thread rolling process for the case of rigid tool (threading head) and elastic/visco-plastic body (pipe or bar). An update Lagrangian formulation was used to describe nonlinear phenomena on a typical incremental step. For solution of discrete equations of motions and deformations of the object the explicit integration method was applied. The algorithm and application of 3D numerical analysis in ANSYS program were elaborated. This algorithm let for determination of influence of friction coefficient, initial yield stress and plastic hardening modulus. This factors influence will be carried out with 5 levels rotary experiment plan, which let for elaboration of regression equation to describe this relationship. Exemplary results of 3D numerical analysis of displacement and strain in thread for different conditions of rolling process are presented.