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1
Ge, Dawei. "Kinematics modeling of redundant manipulator based on screw theory and Newton-Raphson method". Journal of Physics: Conference Series 2246, n. 1 (1 aprile 2022): 012068. http://dx.doi.org/10.1088/1742-6596/2246/1/012068.
Testo completoAbstract (sommario):
Abstract In this paper, forward kinematics and inverse kinematicsis algorithms are proposed to solve the problem that the redundant manipulator has more freedom than the traditional manipulator and cannot directly solve the inverse kinematics analytical solution. Firstly, the forward kinematics model is established through the screw theory; secondly, Newton-Raphson method is used to solve the inverse kinematics of the manipulator. Finally, the algorithms of redundant manipulator are verified through an example simulated by Matlab Robotics toolbox. The results show that the kinematic algorithms are correct, which provides a good algorithm basis for subsequent dynamic control.
2
Purwana, Unang, Dadi Rusdiana e Winny Liliawati. "PENGUJIAN KEMAMPUAN MENGINTERPRETASIKAN GRAFIK KINEMATIKA CALON GURU FISIKA: THE POLYTOMOUS RASCH ANALYSIS". ORBITA: Jurnal Kajian, Inovasi dan Aplikasi Pendidikan Fisika 6, n. 2 (8 novembre 2020): 259. http://dx.doi.org/10.31764/orbita.v6i2.3264.
Testo completoAbstract (sommario):
ABSTRAKKemampuan interpretasi grafik merupakan kemampuan yang sangat penting dan kunci utama dalam memahami materi kinematika dan materi fisika lanjutan. Namun kemampuan interpretasi grafik materi kinematika mahasiswa calon guru masih rendah. Tujuan penelitian ini menguji kemampuan membaca dan menginterpretasikan grafik kinematika calon guru dengan analisis polytomous rasch model. Instrumen terdiri dari empat soal uraian menyajikan grafik kinematika. Tes diberikan ke 20 mahasiswa calon guru, terdiri dari 14 perempuan dan 6 laki-laki. Metode yang digunakan survei deskriptif kuantitatif dengan analisis menggunakan rasch model dengan data politomi. Hasil yang diperoleh nilai reliabilitas 0,58 kategori lemah, tingkat kesukaran untuk 3 soal dalam kategori sukar dan satu soal kategori mudah, daya pembeda berkategori sangat baik untuk seluruh soal. Kemampuan membaca dan menginterpretasikan grafik kinematika secara keseluruhan cukup baik. Kesimpulannya instrumen dan analisis yang digunakan dapat menguji kemampuan menginterpretasikan grafik kinematika calon guru. Kata kunci: interpretasi; grafik, kinematika; polytomous rasch. ABSTRACTThe ability to interpret graphs is a very important ability and the main key in understanding kinematics and advanced physics materials. However, the ability to interpret graphs of prospective teachers is still low. The purpose of this study is to test the ability to read and interpret the kinematic graphs of prospective teachers using polytomous rasch model analysis. The instrument consists of four essay questions presenting a kinematic graph. The test was given to 20 prospective teachers, consisting of 14 females and 6 males. The method used is quantitative descriptive survey with analysis using the rasch model with polytomous data. The results obtained were the reliability value of 0.58 in the weak category, the level of difficulty for 3 questions in the difficult category and one question in the easy category, the distinguishing power was very good for all the questions. The overall ability to read and interpret kinematics graphs is quite good. In conclusion, the instruments and analysis used can test the ability to interpret the prospective teacher's kinematics graph. Keywords: interpretation; graph; kinematics; polytomous.
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Zhao, Rui Feng, Zhen Zhang e Jiu Qiang Cui. "The Kinematics Modeling and Simulation of a Mechanical Arm in Nuclear Industry with Postpositional Drive". Applied Mechanics and Materials 496-500 (gennaio 2014): 754–59. http://dx.doi.org/10.4028/www.scientific.net/amm.496-500.754.
Testo completoAbstract (sommario):
For the particularity of the environment in nuclear industry, this paper puts forward a modularized mechanical arm with postpositional drive. On the basis of structural characteristics and kinematic constraints, the kinematics of robotic arm is analyzed. The D-H method is used for describing the workspace, based on considering the kinematic constraints, the forward kinematics model is achieved. Using an improved search method, the inverse kinematics solution is obtained. Through the simulation on data processing software, the validity of positive kinematics model and inverse kinematic solutions are verified. Finally, the trajectory planning is completed on the three-dimensional modeling platform.
4
Hanuschik, R. W. "FeII line widths as tracers for the geometry of Be star envelopes". Symposium - International Astronomical Union 162 (1994): 265–66. http://dx.doi.org/10.1017/s0074180900215015.
Testo completoAbstract (sommario):
The geometry of Be star envelopes is not directly observable, apart from those very few cases where interferometry has been successful. This is even more true for the kinematical conditions in these envelopes. An indirect measure of kinematics, density law and geometry can be achieved by comparing line widths of photospheric absorption lines (⇔ v* sin i) and circumstellar emission lines (⇔ v(r) sin i). Hitherto existing determinations of line widths have been, however, quite unsatisfactory. The reason is that in these studies Balmer line parameters were used [see Hanuschik (1989) and references therein] which are strongly broadened by radiative transfer and Thomson scattering in addition to kinematic broadening. Because the question of geometry and kinematics is of crucial importance for understanding the Be phenomenon, I have started a new study, using measurements of the Fe ii λ5317 line. This line shows almost optically thin emission and is broadened primarily by kinematics.
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Tan, Yue Sheng, Peng Le Cheng e Ai Ping Xiao. "Inverse Kinematics Solution for a 6R Special Configuration Manipulators Based on Screw Theory". Advanced Materials Research 216 (marzo 2011): 250–53. http://dx.doi.org/10.4028/www.scientific.net/amr.216.250.
Testo completoAbstract (sommario):
Three basic sub-problems of screw theory are acceptable for some particular configuration manipulators’ inverse kinematics, which can not solve the inverse kinematics of all configuration manipulators. This paper introduces two extra extended sub-problems, through which all inverse kinematic solutions for 6-R manipulators having closed-form inverse kinematics can be gained. The inverse kinematic solution for a new particular configuration manipulator is presented.
6
Cho, Dong Kwon, Byoung Wook Choi e Myung Jin Chung. "Optimal conditions for inverse kinematics of a robot manipulator with redundancy". Robotica 13, n. 1 (gennaio 1995): 95–101. http://dx.doi.org/10.1017/s0263574700017525.
Testo completoAbstract (sommario):
SummaryThe algorithms of inverse kinematics based on optimality constraints have some problems because those are based only on necessary conditions for optimality. One of the problems is a switching problem, i.e., an undesirable configuration change from a maximum value of a performance measure to a minimum value may occur and cause an inverse kinematic solution to be unstable. In this paper, we derive sufficient conditions for the optimal solution of the kinematic control of a redundant manipulator. In particular, we obtain the explicit forms of the switching condition for the optimality constraintsbased methods. We also show that the configuration at which switching occurs is equivalent to an algorithmic singularity in the extended Jacobian method. Through a numerical example of a cyclic task, we show the problems of the optimality constraints-based methods. To obtain good configurations without switching and kinematical singularities, we propose a simple algorithm of inverse kinematics.
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Lu, Chen Hua, e Meng Jun Song. "The Research of Rapid Construction Method of Kinematics Coordinate System from a Kind of Mobile Robot". Applied Mechanics and Materials 721 (dicembre 2014): 299–302. http://dx.doi.org/10.4028/www.scientific.net/amm.721.299.
Testo completoAbstract (sommario):
In order to study how to solve the serial robot kinematics quickly, so we transformed the kinematics coordinate system by Y axis, and the computed results show that transforming the kinematics coordinate system by Y axis could solve the kinematic model quickly and efficiently; the computed results suggest that constructing the redundant coordinate system and transforming the kinematics coordinate system by Y axis could solve the serial robotic kinematics efficiently.
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Cai, Lin. "Kinematic Analysis of 5-UPS Parallel Machine Tool Based on Adams". Applied Mechanics and Materials 644-650 (settembre 2014): 215–19. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.215.
Testo completoAbstract (sommario):
In this paper, the kinematics of 5-UPS parallel machine tool is analyzed, and a kinematic analysis method combining kinematic analysis and computer kinematics software is proposed. Under the premise that the parallel machine tool sector parameters is known, firstly we use the vector method to establish a mathematical model of inverse kinematics, and in accordance with a U-shaped processing trajectory the inverse solution is calculated; Secondly, three-dimensional model of the parallel machine tool is modeled in Adams, and kinematic constraints are set correctly; Finally, the inverse kinematics solution of the mathematical model is used as the Adams drive input, then the positive solutions is carried out. Compared through the Adams simulation results with U-machining path, it is verified that the inverse solution of the mathematical model and parallel machine tool bodies both are correct, it has certain significance for Parallel machine tools and other parallel robot kinematics analysis.
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Han, Ziyong, Shihua Yuan, Xueyuan Li e Junjie Zhou. "Enhanced closed-loop systematic kinematics analysis of wheeled mobile robots". International Journal of Advanced Robotic Systems 16, n. 4 (luglio 2019): 172988141986324. http://dx.doi.org/10.1177/1729881419863242.
Testo completoAbstract (sommario):
The traditional homogeneous transform maintains central position in the kinematic modelling of robotics. However, for these kinematic modelling of wheeled mobile robots over uneven terrain, the homogeneous transform that represents angular velocity implicitly in the time derivative of the rotation matrix has a drawback in orientation representation. In this article, to improve the angular representation, a new general systematic method for kinematics modelling and analysis of wheeled mobile robot is proposed. The approach uses the Sheth–Uicker convention and loop-closure kinematic chains to derive the position, velocity and acceleration kinematics. The screw coordinates are used to reform the velocity kinematics to centroidal kinematics; then, the Jacobian calculation is simplified to solve the screw vector algebra equations instead of the matrix equations. Meanwhile, the linear and angular components of the centroidal kinematics are endowed with physical meanings and are easy to be selected as control variables. The approach is applied to a wheeled mobile robot, and its effectiveness is verified by the simulation results with various terrain.
10
Xin, Shi Zhi, Luo Yu Feng, Hang Lu Bing e Yang Ting Li. "A Simple Method for Inverse Kinematic Analysis of the General 6R Serial Robot". Journal of Mechanical Design 129, n. 8 (18 agosto 2006): 793–98. http://dx.doi.org/10.1115/1.2735636.
Testo completoAbstract (sommario):
The inverse kinematic analysis of the general 6R serial robot has been a very significant and important problem in the theory of the spatial mechanisms. Because the solution to inverse kinematics problem of the general 5R serial robot is unique and its assembly condition has been derived, a simple effective method for inverse kinematics problem of general 6R serial robot or forward kinematics problem of general 7R single-loop mechanism is presented based on a one-dimension searching algorithm. All the real solutions to inverse kinematics problems of the general 6R serial robot or forward kinematics problems of the general 7R single-loop mechanism can be obtained. The new method has the following features: (1) using one-dimension searching algorithm, all the real inverse kinematic solutions are obtained and it has higher computing efficiency; and (2) compared with the algebraic method, it has evidently reduced the difficulty of deducing formulas. The principle of the new method can be generalized to kinematic analysis of parallel mechanisms.
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Jatsun, S. F., e Yan Naing Soe. "KINEMATIC AND JACOBIAN ANALYSIS APPROACH FOR THE FOUR-LEGGED ROBOT". Proceedings of the Southwest State University 22, n. 4 (28 agosto 2018): 32–41. http://dx.doi.org/10.21869/2223-1560-2018-22-4-32-41.
Testo completoAbstract (sommario):
This paper presents forward kinematics, inverse kinematics and Jacobian analysis of four-legged robot research. The kinematics analysis is the main problem of the legged robot. The four-legged robots are very complex more than wheeled robots. In this study,the four-legged robot of each leg calculates Denavit-Hartenberg (D-H) method,that is used for forward kinematics and the inverse is used the geometrical and mathematical methods.The Kinematic divided into two categories Forward Kinematic and Inverse Kinematics. The forward kinematic is calculated we knew the leg of endpoint position for the angles (θ1,θ2 and θ3 ). . Inverse kinematics is used to compute the joint angles which will achieve a desired position and orientation of the end-effector relative to the base frame. The Jacobian is one of the most important analyses for controlling smooth trajectory planning and execution in the derivation of the dynamic equation of robot motion.For calculation is used MATLAB software and robot modeling is used Simulink toolbox in MATLAB software. A program is obtained that calculate joint of angular velocity and angles to move from the desired position to target position. In this study are given different angular velocity and angle of the endpoint of the leg. The work mainly focuses on mechanical design, calculation of kinematic analysis, Jacobian function and experiment data of four-legged robots in MATLAB simulation.
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Hanson, Robert B. "Statistical Analysis of Proper Motion Surveys". Symposium - International Astronomical Union 109 (1986): 43–45. http://dx.doi.org/10.1017/s0074180900076385.
Testo completoAbstract (sommario):
Proper motion surveys offer a great deal of data bearing on important astronomical problems such as stellar kinematics and the luminosity function in the solar neighborhood. Major obstacles to the full use of proper motions have long been posed by: (1) incompleteness of proper motion surveys, (2) proper motion bias in kinematic studies, and (3) the indirect approaches and kinematical assumptions needed in traditional luminosity studies.
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Surriani, Atikah, Oyas Wahyunggoro e Adha Imam Cahyadi. "Inverse kinematic solution and singularity avoidance using a deep deterministic policy gradient approach". IAES International Journal of Artificial Intelligence (IJ-AI) 13, n. 3 (1 settembre 2024): 2999. http://dx.doi.org/10.11591/ijai.v13.i3.pp2999-3009.
Testo completoAbstract (sommario):
<p>The robotic arm emerges as a subject of paramount significance within the industrial landscape, particularly in addressing the complexities of its kinematics. A significant research challenge lies in resolving the inverse kinematics of multiple degree of freedom (M-DOF) robotic arms. The inverse kinematics of M-DOF robotic arms pose a challenging problem to resolve, thus it involves consideration of singularities which affect the arm robot movement. This study aims a novel approach utilizing deep reinforcement learning (DRL) to tackle the inverse kinematic problem of the 6-DOF PUMA manipulator as a representative case within the M-DOF manipulator. The research employs Jacobian matrix for the kinematics system that can solve the singularity, and deep deterministic policy gradient (DDPG) as the kinematics solver. This chosen technique offers enhancing speed and ensuring stability. The results of inverse kinematic solution using DDPG were experimentally validated on a 6-DOF PUMA arm robot. The DDPG successfully solves inverse kinematic solution and avoids the singularity with 1,000 episodes and yielding a commendable total reward of 1,018.</p>
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Tian, Fang, Guang Ming Liu e Ke Tao. "Kinematics Analysis for a PRRR Manipulator". Applied Mechanics and Materials 271-272 (dicembre 2012): 1578–81. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.1578.
Testo completoAbstract (sommario):
The PRRR manipulator of the kinematic equation transformation matrix is worked out by using D-H method, the kinematics solutions are derived ；The coordinate transform method and inverse transform method of the robot kinematics equations are derived, the inverse kinematics is derived and a example is given.
15
Ashe, William B., Sarah E. Innis, Julia N. Shanno, Camille J. Hochheimer, Ronald D. Williams, Sarah J. Ratcliffe, J. Randall Moorman e Shrirang M. Gadrey. "Analysis of respiratory kinematics: a method to characterize breaths from motion signals". Physiological Measurement 43, n. 1 (28 gennaio 2022): 015007. http://dx.doi.org/10.1088/1361-6579/ac4d1a.
Testo completoAbstract (sommario):
Abstract Objective. Breathing motion (respiratory kinematics) can be characterized by the interval and depth of each breath, and by magnitude-synchrony relationships between locations. Such characteristics and their breath-by-breath variability might be useful indicators of respiratory health. To enable breath-by-breath characterization of respiratory kinematics, we developed a method to detect breaths using motion sensors. Approach. In 34 volunteers who underwent maximal exercise testing, we used 8 motion sensors to record upper rib, lower rib and abdominal kinematics at 3 exercise stages (rest, lactate threshold and exhaustion). We recorded volumetric air flow signals using clinical exercise laboratory equipment and synchronized them with kinematic signals. Using instantaneous phase landmarks from the analytic representation of kinematic and flow signals, we identified individual breaths and derived respiratory rate (RR) signals at 1 Hz. To evaluate the fidelity of kinematics-derived RR, we calculated bias, limits of agreement, and cross-correlation coefficients (CCC) relative to flow-derived RR. To identify coupling between kinematics and flow, we calculated the Shannon entropy of the relative frequency with which flow landmarks were distributed over the phase of the kinematic cycle. Main Results. We found good agreement in the kinematics-derived and flow-derived RR signals [bias (95% limit of agreement) = 0.1 (± 7) breaths/minute; CCC median (IQR) = 0.80 (0.48–0.91)]. In individual signals, kinematics and flow were well-coupled (entropy 0.9–1.4 across sensors), but the relationship varied within (by exercise stage) and between individuals. The final result was that the flow landmarks did not consistently localize to any particular phase of the kinematic signals (entropy 2.2–3.0 across sensors). Significance. The Analysis of Respiratory Kinematics method can yield highly resolved respiratory rate signals by separating individual breaths. This method will facilitate characterization of clinically significant breathing motion patterns on a breath-by-breath basis. The relationship between respiratory kinematics and flow is much more complex than expected, varying between and within individuals.
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Hirose, James, Atsushi Nishikawa, Yosuke Horiba, Shigeru Inui e Todd C. Pataky. "Integrated jerk as an indicator of affinity for artificial agent kinematics: laptop and virtual reality experiments involving index finger motion during two-digit grasping". PeerJ 8 (15 settembre 2020): e9843. http://dx.doi.org/10.7717/peerj.9843.
Testo completoAbstract (sommario):
Uncanny valley research has shown that human likeness is an important consideration when designing artificial agents. It has separately been shown that artificial agents exhibiting human-like kinematics can elicit positive perceptual responses. However the kinematic characteristics underlying that perception have not been elucidated. This paper proposes kinematic jerk amplitude as a candidate metric for kinematic human likeness, and aims to determine whether a perceptual optimum exists over a range of jerk values. We created minimum-jerk two-digit grasp kinematics in a prosthetic hand model, then added different amplitudes of temporally smooth noise to yield a variety of animations involving different total jerk levels, ranging from maximally smooth to highly jerky. Subjects indicated their perceptual affinity for these animations by simultaneously viewing two different animations side-by-side, first using a laptop, then separately within a virtual reality (VR) environment. Results suggest that (a) subjects generally preferred smoother kinematics, (b) subjects exhibited a small preference for rougher-than minimum jerk kinematics in the laptop experiment, and that (c) the preference for rougher-than minimum-jerk kinematics was amplified in the VR experiment. These results suggest that non-maximally smooth kinematics may be perceptually optimal in robots and other artificial agents.
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Mello Fiori, Júlia, Rodrigo Zacca e Flávio Antônio De Souza Castro. "Training cessation in 12 years old and under Age-Group Swimmers". Revista Andaluza de Medicina del Deporte 15, n. 2 (10 giugno 2021): 43–47. http://dx.doi.org/10.33155/j.ramd.2021.06.004.
Testo completoAbstract (sommario):
Abstract
Objective: to verify if three-weeks of training cessation affects 200 m front crawl performance and kinematics in 12 years old and under age-group swimmers controlling for anthropometric changes.
Method: Sixteen age-group swimmers (11 girls and 5 boys, age: 10.2 ± 1.2 y) performed a 200 m front crawl test (T200) (time trial) PRE- and POST three-weeks (off-season), where performance, kinematics and anthropometrics variables were obtained.
Results: Height increased ~1.0 cm (CI: 0.70 to 1.3 cm; p < 0.001; d = 0.07). Trivial changes were observed for performance (mean diff: 3.3 s CI: -6.7 to 13.9; p = 0.69; d = 0.08) and kinematical variables (p from 0.69 to 0.84; d < 0.001 for all). High intraclass correlations (ICC: 0.69 to 0.84; p < 0.001) were observed for all variables after three-weeks, indicating stability over time.
Conclusion: Three-weeks off-season does not impair swimming T200 performance and kinematic variables in 12 years old and under age-group swimmers.
Keywords: swimming, detraining, performance, kinematics, anthropometrics
18
Bonfanti, P., F. Simien, R. Rampazzo e Ph Prugniel. "Kinematics of early-type galaxies in compact groups: HCG 67, HCG 74 and HCG 79". International Astronomical Union Colloquium 174 (2000): 50–53. http://dx.doi.org/10.1017/s0252921100054749.
Testo completoAbstract (sommario):
AbstractWe present measurements of stellar kinematics for seven early-type galaxies in HCG 67, HCG 74 and HCG 79. These data are aimed at studying the relation between the environment and the dynamics, structure and stellar content of early-type galaxies. In the present three groups, the kinematic features we observed cannot be associated unambiguously to physical interactions. Visible morphological peculiarities do not appear correlated with kinematical perturbations.
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de Oliveira, Andre Schneider, Edson Roberto De Pieri e Ubirajara Franco Moreno. "A new method of applying differential kinematics through dual quaternions". Robotica 35, n. 4 (24 novembre 2015): 907–21. http://dx.doi.org/10.1017/s0263574715000880.
Testo completoAbstract (sommario):
SUMMARYDifferential kinematics is a traditional approach to linearize the mapping between the workspace and joint space. However, a Jacobian matrix cannot be inverted directly in redundant systems or in configurations where kinematic singularities occur. This work presents a novel approach to the solution of differential kinematics through the use of dual quaternions. The main advantage of this approach is to reduce “drift” error in differential kinematics and to ignore the kinematic singularities. An analytical dual-quaternionic Jacobian is defined, which allows for the application of this approach in any robotic system.
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Müller, Andreas. "Kinematic topology and constraints of multi-loop linkages". Robotica 36, n. 11 (2 agosto 2018): 1641–63. http://dx.doi.org/10.1017/s0263574718000619.
Testo completoAbstract (sommario):
SUMMARYModeling the instantaneous kinematics of lower pair linkages using joint screws and the finite kinematics with Lie group concepts is well established on a solid theoretical foundation. This allows for modeling the forward kinematics of mechanisms as well the loop closure constraints of kinematic loops. Yet there is no established approach to the modeling of complex mechanisms possessing multiple kinematic loops. For such mechanisms, it is crucial to incorporate the kinematic topology within the modeling in a consistent and systematic way. To this end, in this paper a kinematic model graph is introduced that gives rise to an ordering of the joints within a mechanism and thus allows to systematically apply established kinematics formulations. It naturally gives rise to topologically independent loops and thus to loop closure constraints. Geometric constraints as well as velocity and acceleration constraints are formulated in terms of joint screws. An extension to higher order loop constraints is presented. It is briefly discussed how the topology representation can be used to amend structural mobility criteria.
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An, Jiping, Xinhong Li, Zhibin Zhang, Guohui Zhang, Wanxin Man, Gangxuan Hu, Junwei He e Dingzhan Yu. "A Novel Method for Inverse Kinematics Solutions of Space Modular Self-Reconfigurable Satellites with Self-Collision Avoidance". Aerospace 9, n. 3 (28 febbraio 2022): 123. http://dx.doi.org/10.3390/aerospace9030123.
Testo completoAbstract (sommario):
Space modular self-reconfigurable satellites (SMSRSs) are a new type of satellite with reconfigurable structures and adjustable functions. The inverse kinematics of the hyper-redundant structure of SMSRSs are difficult to solve by traditional methods. In this paper, the inverse kinematics of SMSRS is transformed into an optimization problem and solved using the optimization method. Moreover, the avoidance of self-collision is implemented in the optimization process. Firstly, the kinematic model of SMSRS is established. Then, to find the more accurate inverse kinematics solutions, a novel Segmented Hybrid CMA-ES and PSO (SHCP) algorithm is proposed. The algorithm is used for three cases of inverse kinematic problems, and the optimization results prove the optimization method is effective to solve the inverse kinematic problem with self-collision avoidance. Compared to the results of PSO variants, meta-heuristic algorithms, and hybrid algorithms, the novel algorithm has higher accuracy, proving its better performance on the inverse kinematics problem of SMSRS.
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Li, Bin Cheng, Dan Yang e Rong Zhi Lu. "Kinematics Analysis and Control System Design of 6-DOF Parallel Kinematic Machine with Matlab and EMC2". Advanced Materials Research 102-104 (marzo 2010): 363–67. http://dx.doi.org/10.4028/www.scientific.net/amr.102-104.363.
Testo completoAbstract (sommario):
This paper obtained the inverse kinematics model through performing kinematic analysis of 6-DOF parallel kinematic machine (PKM) via the MATLAB software. On the basis of that, kinematics inverse module in EMC2(Enhanced Machine Controller) is recompiled and verified through CNC machining simulation, which set up an important foundation for later prototype construction and motor output control.
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Hernandez-Barragan, Jesus, Gabriel Martinez-Soltero, Jorge D. Rios, Carlos Lopez-Franco e Alma Y. Alanis. "A Metaheuristic Optimization Approach to Solve Inverse Kinematics of Mobile Dual-Arm Robots". Mathematics 10, n. 21 (5 novembre 2022): 4135. http://dx.doi.org/10.3390/math10214135.
Testo completoAbstract (sommario):
This work presents an approach to solving the inverse kinematics of mobile dual-arm robots based on metaheuristic optimization algorithms. First, a kinematic analysis of a mobile dual-arm robot is presented. Second, an objective function is formulated based on the forward kinematics equations. The kinematic analysis does not require using any Jacobian matrix nor its estimation; for this reason, the proposed approach does not suffer from singularities, which is a common problem with conventional inverse kinematics algorithms. Moreover, the proposed method solves cooperative manipulation tasks, especially in the case of coordinated manipulation. Simulation and real-world experiments were performed to verify the proposal’s effectiveness under coordinated inverse kinematics and trajectory tracking tasks. The experimental setup considered a mobile dual-arm system based on the KUKA® Youbot® robot. The solution of the inverse kinematics showed precise and accurate results. Although the proposed approach focuses on coordinated manipulation, it can be implemented to solve non-coordinated tasks.
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Harding, Paul, e Heather Morrison. "The Bulge/Halo interface rotational kinematics from [Fe/H] = −3.0 to Solar". Symposium - International Astronomical Union 153 (1993): 297–98. http://dx.doi.org/10.1017/s0074180900123332.
Testo completoAbstract (sommario):
Kinematics and abundances have been determined for a large sample of K giants in a field at ∼2 kpc from the center to study the relationship between the bulge and the halo. There are two different kinematic groups evident. The metal-poor stars have low rotation and high velocity dispersion, and so can be associated with the halo. The metal-richer stars have intermediate rotation. Our data suggest that the bulge and halo could be separate kinematical entities.
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Толстошеев, Андрей, Andrey Tolstosheev, Вячеслав Татаринцев e Vyacheslav Tatarincev. "STRUCTURAL SYNTHESIS OF SELF-ALIGNING GEARS OF INDUSTRIAL ROBOTS WITH PARALLEL KINEMATICS". Bulletin of Bryansk state technical university 2019, n. 4 (14 maggio 2019): 4–13. http://dx.doi.org/10.30987/article_5cb58f4ed2c444.85435034.
Testo completoAbstract (sommario):
The aim of this work is an analysis of excess ties in handler closed kinematics and development of the structural synthesis procedure for self-aligning gears of industrial robots with parallel kinematics. The design of a structure flowchart of a gear without excess ties in the procedure offered is carried out by means of prototype mechanism updating and includes the following stages: the reveal and analysis of excess ties, excess ties elimination, correctness checkup of excess ties elimination. For the excess ties analysis and solution check-up a structural analysis is carried out. At that a handler is presented as a hierarchal structure described by some structural models. The ways for excess ties elimination: the substitution of one kinematic pair for another one with a higher number of mobility; the introduction of an additional link and one kinematic pair into a kinematics; the elimination from the kinematics an extra link with two kinematic pairs; the substitution in the kinematics a flat hinge parallelogram for a forward pair. There are developed some versions of structural diagrams of self-aligning handlers on the basis of an ortho- glide gear. The procedure offered allows defining the number and a type of excess ties in the kinematics of a gear, eliminating excess ties and forming structural diagrams of self-aligning gears with the conservation of basic operating properties on the alternative basis. The application of structural diagrams of handlers without contour excess ties is one of the ways to increase reliability and manufacturability of designs of industrial robots with parallel kinematics.
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Asif, Seemal, e Philip Webb. "Kinematics Analysis of 6-DoF Articulated Robot with Spherical Wrist". Mathematical Problems in Engineering 2021 (2 febbraio 2021): 1–11. http://dx.doi.org/10.1155/2021/6647035.
Testo completoAbstract (sommario):
The aim of the paper is to study the kinematics of the manipulator. The articulated robot with a spherical wrist has been used for this purpose. The Comau NM45 Manipulator has been chosen for the kinematic model study. The manipulator contains six revolution joints. Pieper’s approach has been employed to study the kinematics (inverse) of the robot manipulator. Using this approach, the inverse kinematic problem is divided into two small less complex problems. This reduces the time of analysing the manipulator kinematically. The forward and inverse kinematics has been performed, and mathematical solutions are detailed based on D-H (Denavit–Hartenberg) parameters. The kinematics solution has been verified by solving the manipulator’s motion. It has been observed that the model is accurate as the motion trajectory was smoothly followed by the manipulator.
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Cheng, Xiang Li, Yi Qi Zhou, Cui Peng Zuo e Xiao Hua Fan. "Kinematical Analysis and Simulation of Upper Limb Rehabilitation Robot". Key Engineering Materials 474-476 (aprile 2011): 1315–20. http://dx.doi.org/10.4028/www.scientific.net/kem.474-476.1315.
Testo completoAbstract (sommario):
To assist stroke patients with rehabilitation training, an upper limb rehabilitation robot with an exoskeleton structure and three degrees of freedom (DOF) was developed in this paper. Under the guidance of the theory of rehabilitation medicine, the mechanical design of the robot was completed. Then, the kinematics equations were established by means of homogeneous transformation, including the forward kinematics and the inverse kinematics. The kinematical analysis was carried out and the algebraic solution of inverse kinematics was derived, which provided a theoretical basis for realizing the intelligent control. To validate the performance, the kinematical simulation was conducted, and the simulation results showed that the design of the exoskeleton robot was feasible.
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Zhao, Yong Guo, Yong Fei Xiao e Tie Chen. "Kinematics Analysis for a 4-DOF Palletizing Robot Manipulator". Applied Mechanics and Materials 313-314 (marzo 2013): 937–40. http://dx.doi.org/10.4028/www.scientific.net/amm.313-314.937.
Testo completoAbstract (sommario):
In order to meet theneeds of high-speedpalletizing inlogistics automation industry, a 4 d4-DOF palletizingrobot manipulatorwas designed. Inthis paper,focusing on kinematic analysis, forward kinematics modeland inverse kinematics were introduced in detail.
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Kumar K, Pavan, Murali Mohan J e Srikanth D. "Generalized solution for inverse kinematics problem of a robot using hybrid genetic algorithms". International Journal of Engineering & Technology 7, n. 4.6 (25 settembre 2018): 250. http://dx.doi.org/10.14419/ijet.v7i4.6.20486.
Testo completoAbstract (sommario):
The robot control consists of kinematic control and dynamic control. Control methods of the robot involve forward kinematics and inverse kinematics (IK). In Inverse kinematics the joint angles are found for a given position and orientation of the end effector. Inverse kinematics is a nonlinear problem and has multiple solutions. This computation is required to control the robot arms. A Genetic Algorithm (GA) and Hybrid genetic algorithm (HGA) (Genetic Algorithm in conjunction with Nelder-Mead technique) are proposed for solving the inverse kinematics of a robotic arm. HGA introduces two concepts exploration, exploitation. In an exploration phase, the GA identifies the good areas in entire search space and then exploitation phase is performed inside these areas by using Nelder- mead technique Binary Simulated Crossover and niching strategy for binary tournament selection operator is used. Proposed algorithms can be used on any type of manipulator and the only requirement is the forward kinematic equations, which are easily obtained. As a case study inverse kinematics of a Two Link Elbow Manipulator and PUMA manipulator are solved using GA and HGA in MATLAB. The algorithm is able to find all solutions without any error
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Rosyid, Abdur, Bashar El-Khasawneh e Anas Alazzam. "External Kinematic Calibration of Hybrid Kinematics Machine Utilizing Lower-DOF Planar Parallel Kinematics Mechanisms". International Journal of Precision Engineering and Manufacturing 21, n. 6 (13 dicembre 2019): 995–1015. http://dx.doi.org/10.1007/s12541-019-00261-3.
Testo completoAbstract (sommario):
AbstractThis paper presents the implementation of nonlinear least squares and iterative linear least squares algorithms for external kinematic calibration of a hybrid kinematics machine composed of two 3PRR planar parallel kinematics mechanisms by utilizing a laser tracker. First the hand-eye and robot-world transformations were obtained by a separable closed-form solution and refined by the nonlinear least squares. Subsequently, the geometric parameters of the machine’s mechanisms were estimated using the two algorithms. Due to the rank deficiency, we implemented the nonlinear least squares algorithm through a subset selection approach in which we performed the estimation in two steps. We iterated the closed-form solution of the linear least squares until the solution converges to the actual values. We have shown that the nonlinear least squares algorithm successfully refined the hand-eye and robot-world transformations and outperformed the iterative linear squares algorithm in the estimation of the geometric parameters of the mechanisms.
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Timofeev, G. A., I. Z. Kataev e D. M. Samsonenko. "Research of the Rhombic Mechanism Kinematics". Proceedings of Higher Educational Institutions. Маchine Building, n. 4 (733) (aprile 2021): 12–17. http://dx.doi.org/10.18698/0536-1044-2021-4-12-17.
Testo completoAbstract (sommario):
Designing modern mechanisms and machines is a very complex and iterative process. One of its first stages is the kinematic analysis of mechanisms followed by structural, dynamic, kinetostatic, etc. The scheme of an asymmetric rhombic mechanism with a developed drive arm of the working group is investigated. The kinematics of the characteristic links points of this mechanism is considered: their kinematic pairs and centers of mass. The kinematics of points and links of this mechanism is considered. The main dependencies for determining the analogs of the velocities and accelerations of points and links of the mechanism are presented. To solve the kinematics tasks the Zinoviev’s method of vector contours was used. The results of the kinematic analysis can be used for dynamic and kinetostatic research of the asymmetric rhombic mechanism with a developed drive arm of the working group, as well as for optimization synthesis of its design.
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Kozanek, Michal, Samuel K. Van de Velde, Thomas J. Gill e Guoan Li. "The Contralateral Knee Joint in Cruciate Ligament Deficiency". American Journal of Sports Medicine 36, n. 11 (14 luglio 2008): 2151–57. http://dx.doi.org/10.1177/0363546508319051.
Testo completoAbstract (sommario):
Background Patients with unilateral ligament deficiency are believed to have altered kinematics of the contralateral knee, increasing the risk of contralateral joint injury. Therefore, the contralateral knees might not be a reliable normal kinematic control. Purpose To compare the in vivo kinematics of the uninjured contralateral knees of patients with anterior or posterior cruciate ligament deficiency with knee kinematics of age-matched patients without joint injury. Study Design Controlled laboratory study. Methods Ten subjects with bilateral healthy knees, 10 patients with acute unilateral anterior cruciate ligament injury, and 10 with acute unilateral posterior cruciate ligament injury participated in this study. Kinematics were measured from 0° to 90° of flexion using imaging and 3-dimensional modeling. Results No significant differences were found across the groups in all rotations and translations during weightbearing flexion (P > .9). Conclusion Patients with unilateral cruciate ligament deficiency did not alter kinematics of the contralateral uninjured knee during weightbearing flexion. In addition, these findings suggest that the included patients with anterior cruciate ligament or posterior cruciate ligament deficiency did not have preexisting abnormal kinematics of the knee. Clinical Relevance As the contralateral joint kinematics of the injured patients were not affected by the ipsilateral ligament injury in the short term, physicians and researchers might use the contralateral knee as a reliable normal kinematic control.
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Zhao, Rongbo, Zhiping Shi, Yong Guan, Zhenzhou Shao, Qianying Zhang e Guohui Wang. "Inverse kinematic solution of 6R robot manipulators based on screw theory and the Paden–Kahan subproblem". International Journal of Advanced Robotic Systems 15, n. 6 (1 novembre 2018): 172988141881829. http://dx.doi.org/10.1177/1729881418818297.
Testo completoAbstract (sommario):
The traditional Denavit–Hatenberg method is a relatively mature method for modeling the kinematics of robots. However, it has an obvious drawback, in that the parameters of the Denavit–Hatenberg model are discontinuous, resulting in singularity when the adjacent joint axes are parallel or close to parallel. As a result, this model is not suitable for kinematic calibration. In this article, to avoid the problem of singularity, the product of exponentials method based on screw theory is employed for kinematics modeling. In addition, the inverse kinematics of the 6R robot manipulator is solved by adopting analytical, geometric, and algebraic methods combined with the Paden–Kahan subproblem as well as matrix theory. Moreover, the kinematic parameters of the Denavit–Hatenberg and the product of exponentials-based models are analyzed, and the singularity of the two models is illustrated. Finally, eight solutions of inverse kinematics are obtained, and the correctness and high level of accuracy of the algorithm proposed in this article are verified. This algorithm provides a reference for the inverse kinematics of robots with three adjacent parallel joints.
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Davis, RO, e RJ Siemers. "Derivation and reliability of kinematic measures of sperm motion". Reproduction, Fertility and Development 7, n. 4 (1995): 857. http://dx.doi.org/10.1071/rd9950857.
Testo completoAbstract (sommario):
Studies of sperm movement are relevant in the diagnosis of sperm function and in investigations of cellular biology. Such studies have been traditionally performed by analysing the kinematics of the flagellum or the head. Analysis of the flagellum can provide insights into the cell biological mechanisms responsible for the control of movement. However, the mathematical correspondence between head kinematics and flagellum kinematics is not unique. Therefore, it is not possible to use head kinematics to obtain detailed insights into cell mechanisms or physiology. The accuracy and precision of kinematic measurements are limited by a number of technical and biological factors. Therefore, the interpretation of kinematic data is dependent on a thorough understanding of the assumptions and conditions underlying the analysis. Evaluation of the reliability of kinematic measurements has suffered because no absolute standard for measurement has existed. The development and application of a new standard based on images which were simulated using the equations of motion is described. Because the kinematics of these images are known prior to empirical measurement, the performance of different methods can be determined absolutely. Some kinematic measures are unreliable because they are inappropriate analogues for engineering concepts. The development and use of appropriate engineering measures for the frequency and amplitude of sperm motion is also described. Some types of sperm motion cannot be analysed using kinematic measures (e.g. hyperactivated movement). The concept of the fractal dimension as a more accurate measurement for such motions is introduced. It is concluded that kinematic measurements of sperm motion can provide valuable information about cell biological mechanisms (in the case of the flagellum) and about general membrane and axoneme function (in the case of the head) when the measurements are made under the appropriate conditions, when standard techniques are followed, and when the assumptions underlying the analysis are well understood.
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Kifayat Mammadova, Aytan Aliyeva, Kifayat Mammadova, Aytan Aliyeva, e Nigar Baghirova Nigar Baghirova. "CONSTRUCTION OF THE KINEMATIC MODEL OF ROBOTIC SYSTEMS IN THE MATLAB ENVIRONMENT". ETM - Equipment, Technologies, Materials 16, n. 04 (6 ottobre 2023): 67–75. http://dx.doi.org/10.36962/etm16042023-67.
Testo completoAbstract (sommario):
Robotics has become relatively accessible with low-cost projects, but there is still a need to create models that accurately represent the robot's physical behavior. Creating a virtual platform allows us to test behavioral algorithms using artificial intelligence. In addition, it will enable us to find potential problems in the physical design of the robot. The article describes the methodology of building a kinematic model and simulation of an autonomous robot. The development of a kinematic model and its implementation using several tools are presented. The environment used for the experiment is very close to natural conditions and reflects the kinematic characteristics of the robot. As a result, the simulation of the model following the mobile robot's kinematics is executed and tested in MATLAB. As a study, the m-file creation in MATLAB, its use with the Simulink package, and the solution of the forward and inverse problem of kinematics are shown. In addition to constructing the robot body using Simulink blocks, the structure of the kinematic scheme is simulated using the Denavit-Hartenberg (DH) parameters of the robot without blocks. "Simscape" and "Robotics System Toolbox" packages simulate forward and inverse kinematics using the Simulink package, and the robot's handle and body movement are observed. In the forward kinematics problem, the readings in the Scope compare the signals received from joint one and the end effector. For the inverse kinematic problem, the parameters of the manipulator along the XYZ axes are entered using the "Signal builder" block, and the circular movement of the arm is observed. In contrast, the handle of the manipulator remains fixed at a given point. Keywords: mobile robot, kinematic model, the forward and inverse problem of kinematics, Denavit-Hartenberg parameters, joint types
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Lin, Cheng-Chung, Hsuan-Lun Lu, Tung-Wu Lu, Chia-Yang Wang, Jia-Da Li, Mei-Ying Kuo e Horng-Chuang Hsu. "Reconstruction of Three-Dimensional Tibiofemoral Kinematics Using Single-Plane Fluoroscopy and a Personalized Kinematic Model". Applied Sciences 11, n. 20 (11 ottobre 2021): 9415. http://dx.doi.org/10.3390/app11209415.
Testo completoAbstract (sommario):
Model-based 3D/2D image registration using single-plane fluoroscopy is a common setup to determine knee joint kinematics, owing to its markerless aspect. However, the approach was subjected to lower accuracies in the determination of out-of-plane motion components. Introducing additional kinematic constraints with an appropriate anatomical representation may help ameliorate the reduced accuracy of single-plane image registration. Therefore, this study aimed to develop and evaluate a multibody model-based tracking (MbMBT) scheme, embedding a personalized kinematic model of the tibiofemoral joint for the measurement of tibiofemoral kinematics. The kinematic model was consisted of three ligaments and an articular contact mechanism. The knee joint activities in six volunteers during isolated knee flexion, lunging, and sit-to-stand motions were recorded with a biplane X-ray imaging system. The tibiofemoral kinematics determined with the MbMBT and mediolateral view fluoroscopic images were compared against those determined using biplane fluoroscopic images. The MbMBT was demonstrated to yield tibiofemoral kinematics with precision values in the range from 0.1 mm to 1.1 mm for translations and from 0.2° to 1.3° for rotations. The constraints provided by the kinematic model were shown to effectively amend the nonphysiological tibiofemoral motion and not compromise the image registration accuracy with the proposed MbMBT scheme.
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Semenov, Denis, Vyacheslav Shlyakhtov e Alexandr Rumyantsev. "Kinematic analysis as the basis for training strategy in gymnastics". BIO Web of Conferences 29 (2021): 01012. http://dx.doi.org/10.1051/bioconf/20212901012.
Testo completoAbstract (sommario):
The kinematic analysis of gymnastic skills performance is a widely used research method in sports science. This study presents the experience of applying the method of kinematic analysis in the managing the training process of junior gymnasts on the example of mastering three basic gymnastic skills. The test group included 10 junior male gymnasts of the age 9 to 12. The subject of kinematic analysis was based on comparing gymnasts’ joint angles, angular velocity and angular acceleration parameters. The kinematics parameters of gymnastic skills performance by a highly qualified gymnast became the target model for junior gymnasts. As a result of these targets application in the training of junior gymnasts, changes in the basic skills kinematic parameters were detected. At the end of the study, the kinematics parameters of junior gymnasts became much closer to the model parameters. Thus, the effectiveness of the kinematics analysis method in the training of junior gymnasts was demonstrated.
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Cui, Guohua, Muyuan Sun, Liang Yan, Hongjuan Hou e Haiqiang Zhang. "Kinematic Reliability Solution of 3-UPS-PU Parallel Mechanism Based on Monte Carlo Simulation". Open Mechanical Engineering Journal 9, n. 1 (29 maggio 2015): 324–32. http://dx.doi.org/10.2174/1874155x01509010324.
Testo completoAbstract (sommario):
In order to research kinematic reliability of 3-UPS-PU parallel mechanism, the structure and kinematics analysis were performed. Inverse kinematics equation can be derived by homogeneous coordinate transformation formula. Position and orientation output error forward kinematics model was obtained by the differential transformation on the basis of inverse kinematic solution of the position. The curves of the position and orientation output errors can be plotted with a large batch production by adopting Monte-Carlo simulation method. Then kinematic reliability of the mechanism can be solved through the probability statistics method and theoretical solution method respectively. Finally, these two methods were compared with each other. The results illustrate that the results of the two methods are basically consistent, and the mechanism can be work reliably and stably under general operations, which provides some valuable references for the related future research.
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Campos, A., R. Guenther e D. Martins. "Differential kinematics of parallel manipulators using Assur virtual chains". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 223, n. 7 (24 marzo 2009): 1697–711. http://dx.doi.org/10.1243/09544062jmes1156.
Testo completoAbstract (sommario):
This article introduces the concept of Assur virtual chains and its applications in differential kinematics of parallel manipulators. Using Assur virtual chains, the differential kinematics has a simple matricial formulation and the choice between direct and inverse kinematics is reduced to select primary variables in a homogeneous linear system. Assur virtual chains are also useful for obtaining information about the relative movements or to imposing particular kinematic constraints between two links of a kinematic chain. Additionally, a new systematic algorithm is established to analytically eliminate passive joint velocities and calculate the Jacobian matrices. This elimination approach is based on screw theory concepts such as twist, wrench, and reciprocity; also, graph theory is used for kinematic chain representation. At the end of the article, the method is applied to a 3RRR planar parallel manipulator and a general universal-prismatic-spheric Stewart—Gough platform.
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Shi, Zhi Hui, Xin Lei Ma e Bi Hong Lu. "Research on Collision Method for Irregular Mechanism Kinematics Simulation". Advanced Materials Research 97-101 (marzo 2010): 3418–22. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.3418.
Testo completoAbstract (sommario):
General kinematics simulation is only for regular mechanism about turning in fix axis, shifting on plane as well as their compound motions. However, there is no mature technique supporting kinematic simulation for those mechanisms depending on clearance operation such as lorry couplers. Considering such irregularly mechanism, authors proposed a method based on collision kinematics simulation, and combining structure analysis as well as virtual assembly in Pro/Engineer. According to methods above, authors implemented three postures of coupler operation kinematics simulation, as well as the reliability avaluation for anti-creep of coupler function. This method supplies a practical solution for irregular machine kinematics simulation.
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Freitas, Gustavo M., Antonio C. Leite e Fernando Lizarralde. "Kinematic control of constrained robotic systems". Sba: Controle & Automação Sociedade Brasileira de Automatica 22, n. 6 (dicembre 2011): 559–72. http://dx.doi.org/10.1590/s0103-17592011000600002.
Testo completoAbstract (sommario):
This paper addresses the posture control problem for robotic systems subject to kinematic constraints. The key idea is to consider the kinematic constraints of the mechanisms from their structure equations, instead of explicitly using the constraint equations. A case study for parallel robots and cooperating redundant robots is discussed based on the following concepts: forward kinematics, differential kinematics, singularities and kinematic control. Simulations results, obtained with a Four-Bar linkage mechanism, a planar Gough-Stewart platform and two cooperating robots, illustrate the applicability and versatility of the proposed methodology.
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Williams, Keith R., Rebecca Snow e Chris Agruss. "Changes in Distance Running Kinematics with Fatigue". International Journal of Sport Biomechanics 7, n. 2 (maggio 1991): 138–62. http://dx.doi.org/10.1123/ijsb.7.2.138.
Testo completoAbstract (sommario):
This study investigated changes in kinematics with fatigue during intercollegiate competition, a noncompetitive track run, and a constant speed treadmill run. To account for changes in kinematics resulting from speed differences, regression equations for each individual generated from nonfatigue data were used to predict rested kinematics for speeds matching those of the fatigue conditions. A factor analysis procedure grouped 29 kinematic variables into sets of independent factors, and both factor variables and individual variables were analyzed for changes with fatigue, which were minimal. Only one significant difference was found in the factor variables between nonfatigue and fatigue states. Comparisons of specific kinematic variables showed a significant increase in step length with fatigue, an increased maximal knee flexion angle during swing, and an increased maximal thigh angle during hip flexion. While fatigue did not result in marked changes in kinematics for the group as a whole, changes for individuals were at times large.
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Laschowski, Brock, Naser Mehrabi e John McPhee. "Inverse Dynamics Modeling of Paralympic Wheelchair Curling". Journal of Applied Biomechanics 33, n. 4 (agosto 2017): 294–99. http://dx.doi.org/10.1123/jab.2016-0143.
Testo completoAbstract (sommario):
Paralympic wheelchair curling is an adapted version of Olympic curling played by individuals with spinal cord injuries, cerebral palsy, multiple sclerosis, and lower extremity amputations. To the best of the authors’ knowledge, there has been no experimental or computational research published regarding the biomechanics of wheelchair curling. Accordingly, the objective of the present research was to quantify the angular joint kinematics and dynamics of a Paralympic wheelchair curler throughout the delivery. The angular joint kinematics of the upper extremity were experimentally measured using an inertial measurement unit system; the translational kinematics of the curling stone were additionally evaluated with optical motion capture. The experimental kinematics were mathematically optimized to satisfy the kinematic constraints of a subject-specific multibody biomechanical model. The optimized kinematics were subsequently used to compute the resultant joint moments via inverse dynamics analysis. The main biomechanical demands throughout the delivery (ie, in terms of both kinematic and dynamic variables) were about the hip and shoulder joints, followed sequentially by the elbow and wrist. The implications of these findings are discussed in relation to wheelchair curling delivery technique, musculoskeletal modeling, and forward dynamic simulations.
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Heil, D. P., e Robert Pickels. "The Influence of Bicycle Geometry on Time-Trial Positioning Kinematics and Markers of Performance". International Journal of Physical Education, Fitness and Sports 8, n. 1 (20 gennaio 2019): 11–24. http://dx.doi.org/10.26524/ijpefs1912.
Testo completoAbstract (sommario):
Studies have previously documented how changes in cycling body kinematics are related to submaximal energetics and power output, as well as cycling performance, but few have focused specifically on how body kinematics will vary with changes in bicycle geometry. This study sought to describe kinematic changes resulting from the systematic change of several bicycle geometry variables: Trunk angle (“low” and “high” positions), seat-tube angle (76° and 80°), saddle tilt angle (0° to -10°), saddle sitting position (middle or nose), as well as two types of saddles. Methods: Well-trained cyclists were kinematically evaluated across specific combinations of geometry variables using a modified cycle ergometer at a standard relative power. Standard two dimensional sagittal-view kinematics from the left side were used to summarize a collection of kinematic variables: Trunk angle, hip angle (HA), knee angle, pelvic tilt angle, and two “composite” angles called body position and pelvic position (PP). Finally, each trial was also evaluated for frontal area (FA; m2) from stationary digital photography. Data were evaluated using repeated measures ANOVA (a=0.05) to evaluate change in kinematics between trials, as well as regression analysis to determine predictability of performance markers (HA and FA) from the collection of geometry and kinematic variables. Results: Changing trunk angle had the greatest impact on other kinematic variables, while saddle type had no influence. Regression showed that geometry variables could explain 75-85% of the variability in either HA or FA, while 78-79% of the variation in HA and 83- 84% of FA was explained by PP alone. Conclusions: The composite kinematic measure PP was generally a better predictor of both HA and FA than any combination of geometry variables. These results can serve as a starting point for understanding the interactions between bicycle geometry and body kinematics, both of which are important determinants of power generation and aerodynamic drag.
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Hewitt, Angela L., Laurentiu S. Popa, Siavash Pasalar, Claudia M. Hendrix e Timothy J. Ebner. "Representation of limb kinematics in Purkinje cell simple spike discharge is conserved across multiple tasks". Journal of Neurophysiology 106, n. 5 (novembre 2011): 2232–47. http://dx.doi.org/10.1152/jn.00886.2010.
Testo completoAbstract (sommario):
Encoding of movement kinematics in Purkinje cell simple spike discharge has important implications for hypotheses of cerebellar cortical function. Several outstanding questions remain regarding representation of these kinematic signals. It is uncertain whether kinematic encoding occurs in unpredictable, feedback-dependent tasks or kinematic signals are conserved across tasks. Additionally, there is a need to understand the signals encoded in the instantaneous discharge of single cells without averaging across trials or time. To address these questions, this study recorded Purkinje cell firing in monkeys trained to perform a manual random tracking task in addition to circular tracking and center-out reach. Random tracking provides for extensive coverage of kinematic workspaces. Direction and speed errors are significantly greater during random than circular tracking. Cross-correlation analyses comparing hand and target velocity profiles show that hand velocity lags target velocity during random tracking. Correlations between simple spike firing from 120 Purkinje cells and hand position, velocity, and speed were evaluated with linear regression models including a time constant, τ, as a measure of the firing lead/lag relative to the kinematic parameters. Across the population, velocity accounts for the majority of simple spike firing variability (63 ± 30% of Radj2), followed by position (28 ± 24% of Radj2) and speed (11 ± 19% of Radj2). Simple spike firing often leads hand kinematics. Comparison of regression models based on averaged vs. nonaveraged firing and kinematics reveals lower Radj2 values for nonaveraged data; however, regression coefficients and τ values are highly similar. Finally, for most cells, model coefficients generated from random tracking accurately estimate simple spike firing in either circular tracking or center-out reach. These findings imply that the cerebellum controls movement kinematics, consistent with a forward internal model that predicts upcoming limb kinematics.
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Luo, Xian Hai, e Liang Zhen Li. "Dynamics Automatic Design of Planar Linkage Mechanism Based on Genetic Program". Advanced Materials Research 396-398 (novembre 2011): 2447–51. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.2447.
Testo completoAbstract (sommario):
Regarded planar linkage mechanism kinematic target and execution of kinematic pair constraint reaction restrictions as the quantitative objectives, established the comprehensive dynamic design fitness function with the distance between a kinematics target and execution of a set of practical movement points, and the difference between actual constraint reaction of kinematic pair and its limit. According to multi-branch tree expression and random configuration method to create mechanical initial population, driven by the fitness function, made the mechanical population evolution towards the target requirements by the use of copy, crossover and mutation operators of genetic program. In the evolutionary process, inserted kinematics and dynamics automatic analysis technique, design examples indicated that using a genetic program can search parallel in different mechanical configuration space, dimension space and inertia space, automatically searched to such kinds of mechanisms approximate kinematics target and dynamics requirements, thus fulfilling the dynamics automatic design.
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Staicu, Stefan, Zhufeng Shao, Zhaokun Zhang, Xiaoqiang Tang e Liping Wang. "Kinematic analysis of the X4 translational–rotational parallel robot". International Journal of Advanced Robotic Systems 15, n. 5 (1 settembre 2018): 172988141880384. http://dx.doi.org/10.1177/1729881418803849.
Testo completoAbstract (sommario):
High-speed pick-and-place parallel manipulators have attracted considerable academic and industrial attention because of their numerous commercial applications. The X4 parallel robot was recently presented at Tsinghua University. This robot is a four-degree-of-freedom spatial parallel manipulator that consists of high-speed closed kinematic chains. Each of its limbs comprises an active pendulum and a passive parallelogram, which are connected to the end effector with other revolute joints. Kinematic issues of the X4 parallel robot, such as degree of freedom analysis, inverse kinematics, and singularity locus, are investigated in this study. Recursive matrix relations of kinematics are established, and expressions that determine the position, velocity, and acceleration of each robot element are developed. Finally, kinematic simulations of actuators and passive joints are conducted. The analysis and modeling methods illustrated in this study can be further applied to the kinematics research of other parallel mechanisms.
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Norasi, Hamid, Jordyn Koenig e Gary Mirka. "Effect of Load Weight and Starting Height on the Variability of Trunk Kinematics". Proceedings of the Human Factors and Ergonomics Society Annual Meeting 62, n. 1 (settembre 2018): 905–9. http://dx.doi.org/10.1177/1541931218621208.
Testo completoAbstract (sommario):
Trunk kinematic variables have been used to understand the risk of low back injuries in the workplace. Variability in trunk kinematics has not been explored to the same level. In the current study, it was hypothesized that workplace variables (starting height and load weight) would have an impact on the variability in the kinematic variables describing trunk motion. Ten participants performed a repetitive lifting task under four different conditions representing two levels of load weight and starting height. The Lumbar Motion Monitor was used to capture key trunk kinematic variables from the concentric range of lifting motion. The dominant parameter in this experiment was found to be the starting height of the lift which significantly affected the variability of trunk kinematics in sagittal plane. In the transverse plane neither starting height of the load nor the weight of the load were found to influence the variability of trunk kinematics significantly.
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Loudon, Janice K., e Marcie Swift. "The Relationship Between Hip Kinematics and Iliotibial Band Syndrome (ITBS) in Long Distance Runners: A Critically Appraised Topic". International Journal of Athletic Therapy and Training 21, n. 4 (luglio 2016): 5–11. http://dx.doi.org/10.1123/ijatt.2014-0144.
Testo completoAbstract (sommario):
Clinical Question:Is there evidence to suggest that runners with a history of ITBS demonstrate altered lower extremity kinematics compared with runners without a history of ITBS?Clinical Bottom Line:There is moderate evidence suggesting that hip kinematics differ between runners with a history of ITBS compared with healthy runners. Results are contradictory related to the plane of movement and direction of the kinematic change. In addition, assessing hip kinematics following an exhaustive run may be beneficial to detect change.
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Murphy, Ryan J., Michael D. M. Kutzer, Sean M. Segreti, Blake C. Lucas e Mehran Armand. "Design and kinematic characterization of a surgical manipulator with a focus on treating osteolysis". Robotica 32, n. 6 (3 dicembre 2013): 835–50. http://dx.doi.org/10.1017/s0263574713001082.
Testo completoAbstract (sommario):
SUMMARYThis paper presents a cable-driven dexterous manipulator with a large, open lumen. One specific application for the manipulator is the treatment of the degeneration of bone tissue (osteolysis) during a less-invasive hip revision surgery. Rigid tools used in traditional approaches limit the surgeons' ability to comprehensively treat the osteolysis due to the complex geometries of the lesion. The surgical scenario, testing, kinematic modeling, and image-based inverse kinematics are described. Testing shows 94% coverage of a lesion wall; the kinematic model describes manipulator notch positions within 0.15 mm, while the image-based inverse kinematics has 0.36 mm error. This manipulator is potentially useful in treating osteolytic lesions through (1) effective lesion exploration compared to conventional techniques, and (2) rapidly performing inverse kinematics from visual feedback.