On Squat Jump Exercise

2016 ◽  
Author(s):  
Dumitru I. Caruntu ◽  
Ricardo Moreno
Keyword(s):  
Dynamic Model ◽  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Contact Point ◽  
Point Location ◽  
Squat Jump ◽  
Jump Exercise ◽  
Joint Contact ◽  
Good Agreement

This paper deals with the mechanics of the human leg and forces in the muscles, ligaments, and joint contact in the leg during a squat jump exercise. An inverse dynamics approach is used in this work. A 2-D dynamic model of one limb in the sagittal plane is used to investigate this ballistic task. Results are then compared to data available in the literature. They show good agreement. The response of the ligament forces and the tibio-femoral contact point location during the exercise are reported.

Knee Contact Characteristics During Drop Landing Exercise

2017 ◽  
Author(s):  
Dumitru I. Caruntu ◽  
Ricardo Moreno
Keyword(s):  
Inverse Dynamics ◽  
Contact Point ◽  
Standing Position ◽  
The Body ◽  
Contact Forces ◽  
Drop Landing ◽  
Joint Contact ◽  
Reaction Forces ◽  
The Subject ◽  
D Model

This work investigates the human leg joint contact characteristics during a drop-landing exercise. The contact characteristics consist of tibio-femoral contact forces and contact point, and hip contact forces. An inverse dynamics 2-D model of human leg is used on this ballistic task in order to simplify computation. Experimental data used show a maximum of 100 degrees of flexion angle and ground reaction forces up to 4 times the body weight. All contact forces show a pattern in which they reach large magnitudes at the beginning of landing, decreasing as the subject end the exercise with a standing position.

scholarly journals Compressive Loads on the Lumbar Spine During Lifting: 4D WATBAK versus Inverse Dynamics Calculations

2005 ◽  
Vol 2 (3-4) ◽  
pp. 149-159
Author(s):  
M. H. Cole ◽  
P. N. Grimshaw
Keyword(s):  
Lumbar Spine ◽  
Dynamic Model ◽  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Three Dimensional ◽  
Work Capacity ◽  
Industrial Applications ◽  
Static Compression ◽  
Biomechanical Models ◽  
Occupational Setting

Numerous two- and three-dimensional biomechanical models exist for the purpose of assessing the stresses placed on the lumbar spine during the performance of a manual material handling task. More recently, researchers have utilised their knowledge to develop specific computer-based models that can be applied in an occupational setting; an example of which is 4D WATBAK. The model used by 4D WATBAK bases its predications on static calculations and it is assumed that these static loads reasonably depict the actual dynamic loads acting on the lumbar spine. Consequently, it was the purpose of this research to assess the agreement between the static predictions made by 4D WATBAK and those from a comparable dynamic model. Six individuals were asked to perform a series of five lifting tasks, which ranged from lifting 2.5 kg to 22.5 kg and were designed to replicate the lifting component of the Work Capacity Assessment Test used within Australia. A single perpendicularly placed video camera was used to film each performance in the sagittal plane. The resultant two-dimensional kinematic data were input into the 4D WATBAK software and a dynamic biomechanical model to quantify the compression forces acting at the L4/L5 intervertebral joint. Results of this study indicated that as the mass of the load increased from 2.5 kg to 22.5 kg, the static compression forces calculated by 4D WATBAK became increasingly less than those calculated using the dynamic model (mean difference ranged from 22.0% for 2.5 kg to 42.9% for 22.5 kg). This study suggested that, for research purposes, a validated three-dimensional dynamic model should be employed when a task becomes complex and when a more accurate indication of spinal compression or shear force is required. Additionally, although it is clear that 4D WATBAK is particularly suited to industrial applications, it is suggested that the limitations of such modelling tools be carefully considered when task-risk and employee safety are concerned.

Human Knee Inverse Dynamics Model of Vertical Jump Exercise

2019 ◽  
Vol 14 (10) ◽  
Author(s):  
Dumitru I. Caruntu ◽  
Ricardo Moreno
Keyword(s):  
Inverse Dynamics ◽  
Sagittal Plane ◽  
Vertical Jump ◽  
Contact Forces ◽  
Collateral Ligaments ◽  
Dynamics Model ◽  
Human Knee ◽  
Jump Exercise ◽  
Joint Forces ◽  
Patella Ligament

Abstract This work deals with the dynamics of the human knee during vertical jump exercise. The focus is on the joint forces necessary to produce the jump and to dissipate energy during landing. A two-dimensional (2D) sagittal plane, inverse dynamics human leg model is developed. This model uses data from a motion capture system and force plates in order to predict knee and hip joint forces during the vertical jump exercise. The model consists of three bony structures femur, tibia, and patella, ligament structures to include both cruciate and collateral ligaments, and knee joint muscles. The inverse dynamics model is solved using optimization in order to predict joint forces during this exercise. matlab software package is used for the optimization computations. Results are compared with data available in the literature. This work provides insight regarding contact forces and ligaments forces, muscle forces, and knee and hip contact forces in the vertical jump exercise.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

The Effect of Tibiotalar Fixation on Foot Biomechanics

1997 ◽  
Vol 18 (12) ◽  
pp. 792-797 ◽  
Author(s):  
Jennifer S. Wayne ◽  
Keith W. Lawhorn ◽  
Kenneth E. Davis ◽  
Karanvir Prakash ◽  
Robert S. Adelaar
Keyword(s):  
Subtalar Joint ◽  
Sagittal Plane ◽  
Lower Limbs ◽  
Coronal Plane ◽  
Neutral Position ◽  
Talonavicular Joint ◽  
Tibiotalar Joint ◽  
Contact Areas ◽  
Joint Contact ◽  
Peak Pressures

Contact areas and peak pressures in the posterior facet of the subtalar and the talonavicular joints were measured in cadaver lower limbs for both the normal limb and after fixation of the tibiotalar joint. Six joints were fixed in neutral, in 5–7° of varus and of valgus. Ten degrees of equinus angulation was also studied. Each position of fixation was tested independently. Neutral was defined as fixation without coronal or sagittal plane angulation compared with prefixation alignment of the specimen. When compared with normal unfused condition, peak pressures increased, and contact areas decreased in the subtalar joint for specimens fixed in neutral, varus, and valgus. However, the change in peak pressure for neutral fusion compared with normal control was not statistically significant ( P > 0.07). Peak pressures for varus and valgus fixation were significantly different from normal ( P < 0.001). Contact areas for all positions of fixation were significantly different from normal ( P < 0.001). Coronal plane angulation, however, also resulted in significantly lower contact areas compared with neutral fixation ( P < 0.001). Contact areas and peak pressures in the talonavicular joint did not appear to be substantially affected by tibiotalar fixation with coronal plane angulation. Equinus fixation qualitatively increased contact areas and peak pressures in the talonavicular and posterior facet of the subtalar joint. Neutral alignment of the tibiotalar joint in the coronal and sagittal planes altered subtalar and talonavicular joint contact characteristics the least compared with normal controls. Therefore, ankle fusion in the neutral position would be expected to most closely preserve normal joint biomechanics and may limit the progression of degenerative arthrosis of the subtalar joint.

Adding flexibility to the links of a rigid-link dynamic model of an articulated robot

Robotica ◽  
1989 ◽  
Vol 7 (2) ◽  
pp. 165-168 ◽  
Author(s):  
A. Bodner
Keyword(s):  
Computational Complexity ◽  
Dynamic Model ◽  
Euler Equations ◽  
Inverse Dynamics ◽  
Small Degree ◽  
End Effector ◽  
Rigid Link ◽  
Link Model ◽  
Articulated Robot ◽  
Special Case

SUMMARYA method was developed that takes into account flexibility of robot links in the inverse dynamics calculations. This method uses the Newton-Euler equations and is applicable for special case systems that allow for only a small degree of flexibility. Application of the method should improve the accuracy of the position of the end effector during motion of the robot.The results of this study show that the method can be based entirely on an existing rigid-link model with only minimal changes required as additions. The computational complexity of the method is discussed briefly as well and indicates an increase of computations of slightly more than a factor of two as compared to a rigid-link model for the same robot geometry.

scholarly journals Comparison of Power, Velocity and Force Parameters during Loaded Squat Jump Exercise in the Handball and Arm Wrestling Players

2017 ◽  
Vol 5 (12) ◽  
pp. 92 ◽  
Author(s):  
Ibrahim Can
Keyword(s):  
Measurement System ◽  
Performance Indicator ◽  
Mean Power ◽  
Mean Velocity ◽  
Squat Jump ◽  
National Team ◽  
Jump Exercise ◽  
Significant Difference ◽  
Jump Velocity ◽  
Jump Ability

The purpose of this study was to compare power, velocity and force parameters during loaded squat jump (SJ) exercise in the handball and arm wrestling players. In accordance with this purpose, ten arm wrestling athletes from the Turkish National Team (age: 20,7 ± 3,05 years; height: 175,2 ± 5,55 cm; weight: 71,7 ± 8,17 kg) who had ranks in competitions at World and Europe Am Wrestling Championships and ten handball players (age: 23,0 ± 4,00 years; height: 182,3 ± 6,06 cm; weight: 77,8 ± 11,3 kg) who competed at Turkish handball 1st league participated voluntarily in this study. Subjects were performed loaded SJ exercise using a load equals to 40 % of their body weight and obtained the power, velocity and force values using an isoinertial measurement system (T-Force Dynamic Measurement System). For data analysis, descriptive statistic and Mann Whitney - U analyses were used. According to analysis results, there was a statistically significant difference between jump velocity during loaded SJ of handball players and arm wrestling athletes (p < 0.05). Accordingly, arm wrestling athletes have better jump velocity than handball players in terms of mean velocity (MV) and peak velocity (PV). In addition, it was obtained that there wasn’t a statistically significant difference between handball and arm wrestling players in terms of mean force (MF), mean propulsive force (MPF), peak force (PF), peak power (PP), mean propulsive power (MPP), mean power (MP), time and moving distance to barbell bar during loaded SJ (p > 0.05). Consequently, jump ability is a crucial performance indicator in many sports that require explosive actions and the lower-body muscular power. However, it is not a true approach that athletes competing at sport branches which jump ability is an important performance indicator can display a better performance during loaded SJ.

scholarly journals Force-mediated cellular anisotropy and plasticity dictate the elongation dynamics of embryos

2021 ◽  
Vol 7 (27) ◽  
pp. eabg3264
Author(s):  
Chao Fang ◽  
Xi Wei ◽  
Xueying Shao ◽  
Yuan Lin
Keyword(s):  
Plastic Deformation ◽  
Caenorhabditis Elegans ◽  
Muscle Contraction ◽  
Dynamic Model ◽  
Actin Filaments ◽  
Actin Bundles ◽  
Abnormal Embryo ◽  
Intracellular Forces ◽  
Kinetics Of ◽  
Good Agreement

We developed a unified dynamic model to explain how cellular anisotropy and plasticity, induced by alignment and severing/rebundling of actin filaments, dictate the elongation dynamics of Caenorhabditis elegans embryos. It was found that the gradual alignment of F-actins must be synchronized with the development of intracellular forces for the embryo to elongate, which is then further sustained by muscle contraction–triggered plastic deformation of cells. In addition, we showed that preestablished anisotropy is essential for the proper onset of the process while defects in the integrity or bundling kinetics of actin bundles result in abnormal embryo elongation, all in good agreement with experimental observations.

Study of a synchronizer mechanism through multibody dynamic analysis

2018 ◽  
Vol 233 (6) ◽  
pp. 1601-1613 ◽  
Author(s):  
Ali Farokhi Nejad ◽  
Giorgio Chiandussi ◽  
Vincenzo Solimine ◽  
Andrea Serra
Keyword(s):  
Dynamic Model ◽  
Three Dimensional ◽  
Time Estimation ◽  
Test Rig ◽  
Operational Conditions ◽  
Multibody Dynamic ◽  
Dynamic Analyses ◽  
Single Cone ◽  
Good Agreement ◽  
Numerical Approaches

The synchronizer mechanism represents the essential component in manual, automatic manual, and dual-clutch transmissions. This paper describes a multibody dynamic model for analysis of a synchronizer mechanism subjected to different operational conditions. The three-dimensional multi-dynamic model is developed to predict the dynamic response of synchronizer, especially for calculation of synchronization time. For the purpose of validation, three different synchronizers (single-cone, double-cone, and triple-cone synchronizers) were used on the test rig machine. For the purpose of synchronizing time estimation, an analytical formulation is proposed. The results of the analytical and multibody dynamic analyses were compared with the experimental data, showing a good agreement. The results of analytical and numerical approaches show that the predicted time of synchronization is more precise than previous works. A sensitivity analysis was performed on the single-cone synchronizer, and the effect of tolerance dimension on the dynamic behavior of the synchronizer was reported.

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