scholarly journals KINEMATIC MODELING OF THE TECHNIQUE STALDER BACKWARD TO HANDSTAND ON THE UNEVEN BARS

2019 ◽  
pp. 031
Author(s):  
Emilija Petković
Keyword(s):  
Kinematic Model ◽  
Reference Points ◽  
The Body ◽  
Kinematic Modeling ◽  
Kinematic Parameters ◽  
Successful Performance ◽  
Axis Of Rotation ◽  
Successful Technique ◽  
Female Gymnasts ◽  
Clear Support

Optimizing the technique of successful performance is important for detecting different technique styles that occur in female gymnasts. The aims of this research were to define an optimal kinematic model of the Stalder backward to handstand on the uneven bars exercise, as well as factors that most greatly affect the successful performance of the selected exercise, performed at the 39th and 40th World Cups in Artistic Gymnastics in Maribor (SLO). The sample of participants consisted of eight female gymnasts who participated in the Finals and performed the above mentioned exercise. Kinematic parameters were determined by the use of the Ariel Performance APAS 3-D video system, and anthropometric 16 reference points with four body segments (foot, center of gravity of the body-CG, shoulder joint and head). CG was calculated based on the model presented by Winter in 2009. The results of the research defined the kinematic exercise model that requires four phases: 1) Upswing from a handstand position to balance the resistance front; 2) Downswing to upswing with clear support; 3) Lower vertical passing; 4) Swing to handstand position. Variability of the trajectory of referent points is necessary as an indication of the successful performance of the Stalder backward to handstand on the uneven bars technique. In the current research, the variability for the successful technique for CG trajectory values decreases from -0.767m to -1.045m, while the trajectory values of the shoulder point decrease from 0.689m to 0.488m under the axis of rotation. The information given could optimize the performance of other young gymnasts at all levels of performance.

scholarly journals THE OPTIMAL KINEMATIC MODEL OF THE PERFORMANCE OF THE CLEAR HIP CIRCLE TO HANDSTAND ON THE UNEVEN BARS – A CASE STUDY

2018 ◽  
pp. 229
Author(s):  
Emilija Petković ◽  
Saša Veličković ◽  
Edvard Kolar ◽  
Ratko Stanković ◽  
Daniel Stanković
Keyword(s):  
Elbow Joint ◽  
Kinematic Model ◽  
Reference Points ◽  
The Body ◽  
Kinematic Parameters ◽  
Successful Performance ◽  
World Cup ◽  
Main Method ◽  
Female Gymnasts

The aim of this research was to define the optimal kinematic parameters of performance of the Clear hip circle to handstand on uneven bars (KOVT). The optimal kinematic model defined in this case study represents an example of the successful performance of the Clear hip circle to handstand on the uneven bars. The exercise was performed at the 39th and 40th World Cup in Artistic gymnastics in Maribor (SLO). The kinematic parameters were specified by the APAS 3-D video system (Ariel Dynamics Inc., San Diego, CA), using 16 anthropometric reference points and 8 body segments (Foot, Ankle, Knee joint, Hip joint, Wrist, Elbow joint, Shoulder joint and Head), in which one of the points represents the center of gravity of the body. The female gymnasts (N=15), mean age 17.5 yrs, who performed one Clear hip circle on the uneven bars performed two KOVTs in their gymnastics routine, while the rest performed one KOVT on the uneven bars, mean age 17.5. The main method in this research was kinematic, and the additional one was statistical. Optimizing the technique of successful performance of the KOVT is important for detecting different styles of the technique that occur in female gymnasts.

A Kinematic Model for Parallel-Joint Coordinate Measuring Machine

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Jie Li ◽  
Lian-Dong Yu ◽  
Jing-Qi Sun ◽  
Hao-Jie Xia
Keyword(s):  
Mathematical Modeling ◽  
Data Processing ◽  
Newton Method ◽  
Measurement Accuracy ◽  
Kinematic Model ◽  
Coordinate Measuring Machine ◽  
Experimental Results ◽  
Kinematic Modeling ◽  
Kinematic Parameters ◽  
Measuring Machine

The typical nonorthogonal coordinate measuring machine is the portable coordinate measuring machine (PCMM), which is widely applied in manufacturing. In order to improve the measurement accuracy of PCMM, structural designing, data processing, mathematical modeling, and identification of parameters of PCMM, which are essential for the measurement accuracy, should be taken into account during the machine development. In this paper, a kind of PCMM used for detecting the crucial dimension of automobile chassis has been studied and calibrated. The Denavit–Hartenberg (D–H) kinematic modeling method has often been used for modeling traditional robot, but the D–H error representation is ill-conditioned when it is applied to represent parallel joints. A modified four-parameter model combined with D–H model is put forward for this PCMM. Based on the kinematic model, Gauss–Newton method is applied for calibrating the kinematic parameters. The experimental results indicate the improvement of measuring accuracy and the effectiveness of the PCMM based on the proposed method.

Reference Coordinate System Requirements for Geophysics

1975 ◽  
Vol 26 ◽  
pp. 87-92
Author(s):  
P. L. Bender
Keyword(s):  
Coordinate System ◽  
Polar Motion ◽  
Main Part ◽  
Measurement Techniques ◽  
Reference Points ◽  
Angular Motion ◽  
Coordinate Systems ◽  
Axis Of Rotation ◽  
The Earth ◽  
Fixed System

AbstractFive important geodynamical quantities which are closely linked are: 1) motions of points on the Earth’s surface; 2)polar motion; 3) changes in UT1-UTC; 4) nutation; and 5) motion of the geocenter. For each of these we expect to achieve measurements in the near future which have an accuracy of 1 to 3 cm or 0.3 to 1 milliarcsec.From a metrological point of view, one can say simply: “Measure each quantity against whichever coordinate system you can make the most accurate measurements with respect to”. I believe that this statement should serve as a guiding principle for the recommendations of the colloquium. However, it also is important that the coordinate systems help to provide a clear separation between the different phenomena of interest, and correspond closely to the conceptual definitions in terms of which geophysicists think about the phenomena.In any discussion of angular motion in space, both a “body-fixed” system and a “space-fixed” system are used. Some relevant types of coordinate systems, reference directions, or reference points which have been considered are: 1) celestial systems based on optical star catalogs, distant galaxies, radio source catalogs, or the Moon and inner planets; 2) the Earth’s axis of rotation, which defines a line through the Earth as well as a celestial reference direction; 3) the geocenter; and 4) “quasi-Earth-fixed” coordinate systems.When a geophysicists discusses UT1 and polar motion, he usually is thinking of the angular motion of the main part of the mantle with respect to an inertial frame and to the direction of the spin axis. Since the velocities of relative motion in most of the mantle are expectd to be extremely small, even if “substantial” deep convection is occurring, the conceptual “quasi-Earth-fixed” reference frame seems well defined. Methods for realizing a close approximation to this frame fortunately exist. Hopefully, this colloquium will recommend procedures for establishing and maintaining such a system for use in geodynamics. Motion of points on the Earth’s surface and of the geocenter can be measured against such a system with the full accuracy of the new techniques.The situation with respect to celestial reference frames is different. The various measurement techniques give changes in the orientation of the Earth, relative to different systems, so that we would like to know the relative motions of the systems in order to compare the results. However, there does not appear to be a need for defining any new system. Subjective figures of merit for the various system dependon both the accuracy with which measurements can be made against them and the degree to which they can be related to inertial systems.The main coordinate system requirement related to the 5 geodynamic quantities discussed in this talk is thus for the establishment and maintenance of a “quasi-Earth-fixed” coordinate system which closely approximates the motion of the main part of the mantle. Changes in the orientation of this system with respect to the various celestial systems can be determined by both the new and the conventional techniques, provided that some knowledge of changes in the local vertical is available. Changes in the axis of rotation and in the geocenter with respect to this system also can be obtained, as well as measurements of nutation.

scholarly journals Realtime Motion Assessment For Rehabilitation Exercises: Integration Of Kinematic Modeling With Fuzzy Inference

2014 ◽  
Vol 4 (4) ◽  
pp. 267-285 ◽  
Author(s):  
Wenbing Zhao ◽  
Roanna Lun ◽  
Deborah D. Espy ◽  
M. Ann Reinthal
Keyword(s):  
Fuzzy Inference ◽  
Kinematic Model ◽  
Integrated Approach ◽  
Kinematic Modeling ◽  
Motion Data ◽  
Fuzzy Interference System ◽  
Novel Approach ◽  
Motion Assessment ◽  
Rehabilitation Exercises ◽  
Rehabilitation Exercise

Abstract This article describes a novel approach to realtime motion assessment for rehabilitation exercises based on the integration of comprehensive kinematic modeling with fuzzy inference. To facilitate the assessment of all important aspects of a rehabilitation exercise, a kinematic model is developed to capture the essential requirements for static poses, dynamic movements, as well as the invariance that must be observed during an exercise. The kinematic model is expressed in terms of a set of kinematic rules. During the actual execution of a rehabilitation exercise, the similarity between the measured motion data and the model is computed in terms of their distances, which are then used as inputs to a fuzzy interference system to derive the overall quality of the execution. The integrated approach provides both a detailed categorical assessment of the overall execution of the exercise and the degree of adherence to individual kinematic rules.

scholarly journals III. Researches in physical astronomy

1831 ◽  
Vol 121 ◽  
pp. 17-66
Keyword(s):  
Angular Velocity ◽  
Major Axis ◽  
The Body ◽  
Fixed Plane ◽  
Resisting Medium ◽  
Axis Of Rotation ◽  
Geographical Latitude ◽  
The Mean ◽  
The Stability ◽  
Revolving Body

In last April I had the honour of presenting to the Society a paper containing expressions for the variations of the elliptic constants in the theory of the motions of the planets. The stability of the solar system is established by means of these expressions, if the planets move in a space absolutely devoid of any resistance*, for it results from their form that however far the ap­proximation be carried, the eccentricity, the major axis, and the tangent of the inclination of the orbit to a fixed plane, contain only periodic inequalities, each of the three other constants, namely, the longitude of the node, the longitude of the perihelion, and the longitude of the epoch, contains a term which varies with the time, and hence the line of apsides and the line of nodes revolve continually in space. The stability of the system may therefore be inferred, which would not be the case if the eccentricity, the major axis, or the tangent of the inclination of the orbit to a fixed plane contained a term varying with the time, however slowly. The problem of the precession of the equinoxes admits of a similar solution; of the six constants which determine the position of the revolving body, and the axis of instantaneous rotation at any moment, three have only periodic inequalities, while each of the other three has a term which varies with the time. From the manner in which these constants enter into the results, the equilibrium of the system may be inferred to be stable, as in the former case. Of the constants in the latter problem, the mean angular velocity of rotation may be considered analogous to the mean motion of a planet, or its major axis ; the geographical longitude, and the cosine of the geographical latitude of the pole of the axis of instantaneous rotation, to the longitude of the perihelion and the eccentricity; the longitude of the first point of Aries and the obliquity of the ecliptic, to the longitude of the node and the inclination of the orbit to a fixed plane; and the longitude of a given line in the body revolving, passing through its centre of gravity, to the longitude of the epoch. By the stability of the system I mean that the pole of the axis of rotation has always nearly the same geographical latitude, and that the angular velocity of rotation, and the obliquity of the ecliptic vary within small limits, and periodically. These questions are considered in the paper I now have the honour of submitting to the Society. It remains to investigate the effect which is produced by the action of a resisting medium; in this case the latitude of the pole of the axis of rotation, the obliquity of the ecliptic, and the angular velocity of rotation might vary considerably, although slowly, and the climates undergo a con­siderable change.

scholarly journals KINEMATIC PARAMETERS OF JUMP SHOT IN ELITE MALE BASKETBALL PLAYERS

2019 ◽  
pp. 237
Author(s):  
Emilija Stojanović ◽  
Marko Radenković ◽  
Saša Bubanj ◽  
Ratko Stanković
Keyword(s):  
Body Height ◽  
The Body ◽  
Release Time ◽  
Kinematic Parameters ◽  
Basketball Players ◽  
The Relationship ◽  
Lower Angle

The primary aim of this study was to determine kinematic parameters of jump shot in elite male basketball players, by analyzing the release time for shooting, the angle of entry, and ball spin and. The secondary aim of this study was to examine possible differences in these kinematic parameters among the players associated with their playing position. Eighteen male basketball players (7 guards, 8 forwards, 3 centers) from six Serbian senior teams were tested. 94Fifty basketball sensor was used to obtain the following kinematic parameters of jump shot). The highest average measured values of shot release time were found in centres (1.23±0.23 s) and the lowest in guards (1.07±0.28 s), although these differences were not statistically significant. Further, centres had a lower angle of entry (36.6±2.08°) than guards (40.54±4.76°) and forwards (42.05±3.77°). The highest value of backspin was obtained by forwards (130±11.91 rotations / min). There were no significant differences between guards, forwards and centers in any kinematic variables (p>.01). The relationship between the body height and angle of entry was not significant (p>0.05). In conclusion, compared to centers, guards and forwards showed similar results for the examined variables. This evidence seems to support the theory that compared to guards and forwards centres have the weaker shooting techniques. Coaches should encourage all players, especially centers, to shoot from all positions.

scholarly journals A Technique for the Cultivation of Insect Tissues

1928 ◽  
Vol 6 (1) ◽  
pp. 1-11
Author(s):  
J. G. H. FREW
Keyword(s):  
Tissue Culture ◽  
Culture Media ◽  
Body Fluids ◽  
The Body ◽  
Blow Fly ◽  
In Vitro Tissue Culture ◽  
Successful Technique

In vitro tissue culture Is shown to be a possible mode of experimentation with the tissues of the Blow Fly larva. Methods are described- whereby the tissues, and the body fluids requisite as culture media may be obtained free from bacteria. The imperfections of the technique are noted and the conclusion reached that a successful technique must depend on the rearing of bacteria-free larvae, for which a method Is briefly outlined. It Is shown that progress in this part of the work must await further physiological knowledge, particularly in respect to the nature of the body fluids.

scholarly journals Kinematic Modeling of Six-Axis Industrial Robot and its Parameter Identification: A Tutorial

2021 ◽  
Vol 15 (5) ◽  
pp. 599-610
Author(s):  
Md. Moktadir Alam ◽  
◽  
Soichi Ibaraki ◽  
Koki Fukuda
Keyword(s):  
Present Model ◽  
Industrial Robot ◽  
Local Coordinate System ◽  
Kinematic Model ◽  
Kinematic Modeling ◽  
Positioning Accuracy ◽  
Rotary Axis ◽  
Model Based ◽  
Absolute Positioning ◽  
The Absolute

In advanced industrial applications, like machining, the absolute positioning accuracy of a six-axis robot is indispensable. To improve the absolute positioning accuracy of an industrial robot, numerical compensation based on positioning error prediction by the Denavit and Hartenberg (D-H) model has been investigated extensively. The main objective of this study is to review the kinematic modeling theory for a six-axis industrial robot. In the form of a tutorial, this paper defines a local coordinate system based on the position and orientation of the rotary axis average lines, as well as the derivation of the kinematic model based on the coordinate transformation theory. Although the present model is equivalent to the classical D-H model, this study shows that a different kinematic model can be derived using a different definition of the local coordinate systems. Subsequently, an algorithm is presented to identify the error sources included in the kinematic model based on a set of measured end-effector positions. The identification of the classical D-H parameters indicates a practical engineering application of the kinematic model for improving a robot’s positioning accuracy. Furthermore, this paper presents an extension of the present model, including the angular positioning deviation of each rotary axis. The angular positioning deviation of each rotary axis is formed as a function of the axis’ command angles and the direction of its rotation to model the effect of the rotary axis backlash. The identification of the angular positioning deviation of each rotary axis and its numerical compensation are presented, along with their experimental demonstration. This paper provides an essential theoretical basis for the error source diagnosis and error compensation of a six-axis robot.

scholarly journals Operation of the alula as an indicator of gear change in hoverflies

2011 ◽  
Vol 9 (71) ◽  
pp. 1194-1207 ◽  
Author(s):  
Simon M. Walker ◽  
Adrian L. R. Thomas ◽  
Graham K. Taylor
Keyword(s):  
High Speed ◽  
Aerodynamic Force ◽  
Angular Acceleration ◽  
The State ◽  
The Body ◽  
Kinematic Parameters ◽  
Wing Kinematics ◽  
Change Mechanism ◽  
The Third ◽  
Gear Change

The alula is a hinged flap found at the base of the wings of most brachyceran Diptera. The alula accounts for up to 10 per cent of the total wing area in hoverflies (Syrphidae), and its hinged arrangement allows the wings to be swept back over the thorax and abdomen at rest. The alula is actuated via the third axillary sclerite, which is a component of the wing hinge that is involved in wing retraction and control. The third axillary sclerite has also been implicated in the gear change mechanism of flies. This mechanism allows rapid switching between different modes of wing kinematics, by imposing or removing contact with a mechanical stop limiting movement of the wing during the lower half of the downstroke. The alula operates in two distinct states during flight—flipped or flat—and we hypothesize that its state indicates switching between different flight modes. We used high-speed digital video of free-flying hoverflies ( Eristalis tenax and Eristalis pertinax ) to investigate whether flipping of the alula was associated with changes in wing and body kinematics. We found that alula state was associated with different distributions of multiple wing kinematic parameters, including stroke amplitude, stroke deviation angle, downstroke angle of incidence and timing of supination. Changes in all of these parameters have previously been linked to gear change in flies. Symmetric flipping of the alulae was associated with changes in the symmetric linear acceleration of the body, while asymmetric flipping of the alulae was associated with asymmetric angular acceleration of the body. We conclude that the wings produce less aerodynamic force when the alula is flipped, largely as a result of the accompanying changes in wing kinematics. The alula changes state at mid-downstroke, which is the point at which the gear change mechanism is known to come into effect. This transition is accompanied by changes in the other wing kinematic parameters. We therefore find that the state of the alula is linked to the same parameters as are affected by the gear change mechanism. We conclude that the state of the alula does indeed indicate the operation of different flight modes in Eristalis , and infer that a likely mechanism for these changes in flight mode is the gear change mechanism.

A new approach of kinematic geometry for error identification and compensation of industrial robots

2018 ◽  
Vol 233 (5) ◽  
pp. 1783-1794
Author(s):  
Zhi Wang ◽  
Huimin Dong ◽  
Shaoping Bai ◽  
Delun Wang
Keyword(s):  
Curve Fitting ◽  
Kinematic Model ◽  
Coordinate Measuring Machine ◽  
Reference Points ◽  
Industrial Robots ◽  
Kinematic Calibration ◽  
Kinematic Pair ◽  
Good Efficiency ◽  
New Approach ◽  
Measuring Machine

A new approach for kinematic calibration of industrial robots, including the kinematic pair errors and the link errors, is developed in this paper based on the kinematic invariants. In most methods of kinematic calibration, the geometric errors of the robots are considered in forms of variations of the link parameters, while the kinematic pairs are assumed ideal. Due to the errors of mating surfaces in kinematic pairs, the fixed and moving axes of revolute pairs, or the fixed and moving guidelines of prismatic pairs, are separated, which can be concisely identified as the kinematic pair errors and the link errors by means of the kinematic pair errors model, including the self-adaption fitting of a ruled surface, or the spherical image curve fitting and the striction curve fitting. The approach is applied to the kinematic calibration of a SCARA robot. The discrete motion of each kinematic pair in the robot is completely measured by a coordinate measuring machine. Based on the global kinematic properties of the measured motion, the fixed and moving axes, or guidelines, of the kinematic pairs are identified, which are invariants unrelated to the positions of the measured reference points. The kinematic model of the robot is set up using the identified axes and guidelines. The results validate the approach developed has good efficiency and accuracy.

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