scholarly journals Task dependency of movement regulation in female gymnastic vaulting

2015 ◽  
Vol 7 (4) ◽  
pp. 61-72
Author(s):  
THOMAS HEINEN ◽  
ISABELL ARTMANN ◽  
ANJA BRINKER ◽  
MARC NICOLAUS
Keyword(s):  
Environmental Information ◽  
Task Demands ◽  
Movement Behavior ◽  
Balance Beam ◽  
Foot Placement ◽  
One Step ◽  
Task Dependency ◽  
Run Up ◽  
Two Parameters ◽  
Female Gymnasts

Background: In gymnastics vaulting it is thought that gymnasts regulate their run-up on the basis of visually perceived environmental information, such as the position of the springboard, with the aim of an accurate foot placement on the springboard. The question, however, arises if these regulative processes found in gymnastics vaulting can be generalized to other tasks with similar demands but differing dynamics? Material/Methods: To answer this question, ten female gymnasts were asked to perform two target-directed gymnastics tasks that were similar in task demands but differed in task dy-namics. When performing the two tasks, the position of the springboard was manipulated without the gymnast’s awareness. Results: Results revealed that manipulating the position of the springboard had neither an effect on the distance of the hurdle, nor on the placement of the feet on the spring-board during the reactive leap. The two parameters, however, clearly differed between experimental tasks. Additionally, regulation during run-up occurred on average one step earlier when performing the tucked leap on the balance beam. Conclusions: It can be concluded from the results that gymnasts exhibit a different movement behavior when performing tasks with similar demands but different dynamics, thereby integrating environmental information in the regulation of the run-up and the reactive leap from trial to trial.

Forties Swing, Hollywood Flash

2021 ◽  
pp. 127-156
Author(s):  
Constance Valis Hill
Keyword(s):  
Twentieth Century ◽  
Swing Era ◽  
Stormy Weather ◽  
One Step ◽  
Run Up ◽  
Half Minute

This chapter discusses the Hollywood musical films of the Nicholas Brothers under a five-year contract with Twentieth Century-Fox that brought them to the highest level of notoriety as jazz tap dancers in the Swing era. In Down Argentine Way, despite the mere three-and-a-half-minute scene in which the Brothers appeared, audiences flocked to the theater to see them perform the title song. In Sun Valley Serenade, with Dorothy Dandridge, the Brothers’ Chattanooga Choo Choo number was the aural and visual embodiment of swing music. In Orchestra Wives, Harold performed a run-up-the-wall into a backward flip and split that had never before been seen on film. And in their spectacular Jumping Jive number in Stormy Weather, Fayard jumped down one step and landed in a split, Harold leap-frogged over Fayard and landed on the next step into another split, and the Brothers alternately jumped over each other until they reached the bottom of the stairs—a routine Fred Astaire said was the greatest he had ever seen on film.

scholarly journals Nonlinear run-ups of regular waves on sloping structures

2012 ◽  
Vol 12 (12) ◽  
pp. 3811-3820 ◽  
Author(s):  
T.-W. Hsu ◽  
S.-J. Liang ◽  
B.-D. Young ◽  
S.-H. Ou
Keyword(s):  
Boussinesq Equations ◽  
Irregular Waves ◽  
Coastal Structures ◽  
Regular Waves ◽  
Wave Flume ◽  
Coastal Risk ◽  
Run Up ◽  
Two Parameters ◽  
Prediction Capability ◽  
Good Agreement

Abstract. For coastal risk mapping, it is extremely important to accurately predict wave run-ups since they influence overtopping calculations; however, nonlinear run-ups of regular waves on sloping structures are still not accurately modeled. We report the development of a high-order numerical model for regular waves based on the second-order nonlinear Boussinesq equations (BEs) derived by Wei et al. (1995). We calculated 160 cases of wave run-ups of nonlinear regular waves over various slope structures. Laboratory experiments were conducted in a wave flume for regular waves propagating over three plane slopes: tan α =1/5, 1/4, and 1/3. The numerical results, laboratory observations, as well as previous datasets were in good agreement. We have also proposed an empirical formula of the relative run-up in terms of two parameters: the Iribarren number ξ and sloping structures tan α. The prediction capability of the proposed formula was tested using previous data covering the range ξ ≤ 3 and 1/5 ≤ tan α ≤ 1/2 and found to be acceptable. Our study serves as a stepping stone to investigate run-up predictions for irregular waves and more complex geometries of coastal structures.

One step at a time: animating virtual characters based on foot placement

2010 ◽  
Vol 26 (6-8) ◽  
pp. 497-503 ◽  
Author(s):  
Arjan Egges ◽  
Ben van Basten
Keyword(s):  
Virtual Characters ◽  
Foot Placement ◽  
One Step

scholarly journals Differences between all-around results in women’s artistic gymnastics and ways of minimizing them

2020 ◽  
Vol 12 (3) ◽  
pp. 80-91
Author(s):  
ALMIR ATIKOVIĆ ◽  
EDINA KAMENJAŠEVIĆ ◽  
AMRA NOŽINOVIĆ MUJANOVIĆ ◽  
EDIN UŽIČANIN ◽  
MUHAMED TABAKOVIĆ ◽  
...  
Keyword(s):  
Balance Beam ◽  
Female Gymnasts

Background: In the present study, the main goal was to establish whether the disciplines are equal and should the Code of Points (COP) women's artistic gymnastics be revised in terms of point standardization on apparatus. Material and methods: The sample included all-around senior female gymnasts who participated in the qualification (C-I) competitions at World Championships held in 2009-2019. Results: The biggest differences are even two points between the two apparatus vault and balance beam. Vault compared to other apparatus is different for 1.559 points. Presentation of correlations between each apparatus the evidence that nothing has changed significantly in recent years, whereas correlations of the difficulty values of elements are extremely high between the present COP. Conclusions: With this analysis, we have found that the results achieved at the vault and other apparatus were significantly different in terms of success in all-around competition.

scholarly journals Outlier Detection at GBIF Using DBSCAN

2020 ◽  
Vol 4 ◽  
Author(s):  
John Waller
Keyword(s):  
Outlier Detection ◽  
Clustering Algorithm ◽  
Spatial Databases ◽  
Additional Data ◽  
Environmental Information ◽  
Environmental Data ◽  
Data Sources ◽  
Detection Methods ◽  
Choose Parameter ◽  
Two Parameters

Geographic outliers at GBIF (Global Biodiversity Information Facility) are a known problem. Outliers can be errors, coordinates with high uncertainty, or simply occurrences from an undersampled region. Often in data cleaning pipelines, outliers are removed (even if they are legitimate points) because the researcher does not have time to verify each record one-by-one. Outlier points are usually occurrences that need attention. Currently, there is no outlier detection implemented at GBIF and it is up to the user to flag outliers themselves. DBSCAN (a density-based algorithm for discovering clusters in large spatial databases with noise) is a simple and popular clustering algorithm. It uses two parameters, (1) distance and (2) a minimum number of points per cluster, to decide if something is an outlier. Since occurrence data can be very patchy, non-clustering distance-based methods will fail often Fig. 1. DBSCAN does not need to know the expected number of clusters in advance. DBSCAN does well using only distance and does not require some additional environmental variables like Bioclim. Advanatages of DBSCAN : Simple Easy to understand Only two parameters to set Scales well No additional data sources needed Users would understand how their data was changed Simple Easy to understand Only two parameters to set Scales well No additional data sources needed Users would understand how their data was changed Drawbacks : Only uses distance Must choose parameter settings Sensitive to sparse global sampling Does not include any other relevant environmental information Can only flag outliers outside of a point blob Only uses distance Must choose parameter settings Sensitive to sparse global sampling Does not include any other relevant environmental information Can only flag outliers outside of a point blob Outlier detection and error detection are different. If your goal is to produce a system with no false positives, it will fail. While more complex environmentally-informed outlier detection methods (like reverse jackknifing (Chapman 2005)) might perform better for certain examples or even in genreal, DBSCAN performs adequately on almost everything despite being very simple. Currently I am using DBSCAN to find errors and assess dataset quality. It is a Spark job written in Scala (github). It does not run on species with lots of (>30K) unique latitude-longitude points, since the current implementation relies on an in-memory distance matrix. However, around 99% of species (plants, animals, fungi) on GBIF have fewer than >30K unique lat-long points (2,283 species keys / 222,993 species keys). There are other implementations ( example) that might scale to many more points. There are no immediate plans to include DBSCAN outliers as a data quality flag on GBIF, but it could be done somewhat easily, since this type of method does not rely on any external environmental data sources and already runs on the GBIF cluster.

scholarly journals One-Step Deadbeat Control of a 5-Link Biped Using Data-Driven Nonlinear Approximation of the Step-to-Step Dynamics

Robotics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 90
Author(s):  
Pranav A. Bhounsule ◽  
Ernesto Hernandez-Hinojosa ◽  
Adel Alaeddini
Keyword(s):  
Torque Control ◽  
Deadbeat Control ◽  
Computationally Efficient ◽  
Foot Placement ◽  
Affine Model ◽  
Computed Torque Control ◽  
Process Error ◽  
One Step ◽  
Step Dynamics ◽  
Computed Torque

For bipedal robots to walk over complex and constrained environments (e.g., narrow walkways, stepping stones), they have to meet precise control objectives of speed and foot placement at every single step. This control that achieves the objectives precisely at every step is known as one-step deadbeat control. The high dimensionality of bipedal systems and the under-actuation (number of joint exceeds the actuators) presents a formidable computational challenge to achieve real-time control. In this paper, we present a computationally efficient method for one-step deadbeat control and demonstrate it on a 5-link planar bipedal model with 1 degree of under-actuation. Our method uses computed torque control using the 4 actuated degrees of freedom to decouple and reduce the dimensionality of the stance phase dynamics to a single degree of freedom. This simplification ensures that the step-to-step dynamics are a single equation. Then using Monte Carlo sampling, we generate data for approximating the step-to-step dynamics followed by curve fitting using a control affine model and a Gaussian process error model. We use the control affine model to compute control inputs using feedback linearization and fine tune these using iterative learning control using the Gaussian process error enabling one-step deadbeat control. We demonstrate the approach in simulation in scenarios involving stabilization against perturbations, following a changing velocity reference, and precise foot placement. We conclude that computed torque control-based model reduction and sampling-based approximation of the step-to-step dynamics provides a computationally efficient approach for real-time one-step deadbeat control of complex bipedal systems.

Validating Determinants for an Alternate Foot Placement Selection Algorithm During Human Locomotion in Cluttered Terrain

2007 ◽  
Vol 98 (4) ◽  
pp. 1928-1940 ◽  
Author(s):  
Renato Moraes ◽  
Fran Allard ◽  
Aftab E. Patla
Keyword(s):  
Dynamic Stability ◽  
Center Of Mass ◽  
Frontal Plane ◽  
Human Locomotion ◽  
The Body ◽  
Selection Algorithm ◽  
Foot Placement ◽  
Double Support ◽  
One Step ◽  
Base Of Support

The goal of this study was to validate dynamic stability and forward progression determinants for the alternate foot placement selection algorithm. Participants were asked to walk on level ground and avoid stepping, when present, on a virtual white planar obstacle. They had a one-step duration to select an alternate foot placement, with the task performed under two conditions: free (participants chose the alternate foot placement that was appropriate) and forced (a green arrow projected over the white planar obstacle cued the alternate foot placement). To validate the dynamic stability determinant, the distance between the extrapolated center of mass (COM) position, which incorporates the dynamics of the body, and the limits of the base of support was calculated in both anteroposterior (AP) and mediolateral (ML) directions in the double support phase. To address the second determinant, COM deviation from straight ahead was measured between adaptive and subsequent steps. The results of this study showed that long and lateral choices were dominant in the free condition, and these adjustments did not compromise stability in both adaptive and subsequent steps compared with the short and medial adjustments, which were infrequent and adversely affected stability. Therefore stability is critical when selecting an alternate foot placement in a cluttered terrain. In addition, changes in the plane of progression resulted in small deviations of COM from the endpoint goal. Forward progression of COM was maintained even for foot placement changes in the frontal plane, validating this determinant as part of the selection algorithm.

scholarly journals A Discrete Control Lyapunov Function for Exponential Orbital Stabilization of the Simplest Walker

2017 ◽  
Vol 9 (5) ◽  
Author(s):  
Pranav A. Bhounsule ◽  
Ali Zamani
Keyword(s):  
Lyapunov Function ◽  
Rate Of Convergence ◽  
Basin Of Attraction ◽  
Discrete Control ◽  
Control Lyapunov Function ◽  
Foot Placement ◽  
Modeling Errors ◽  
Orbital Stabilization ◽  
One Step ◽  
The One

Abstract In this paper, we demonstrate the application of a discrete control Lyapunov function (DCLF) for exponential orbital stabilization of the simplest walking model supplemented with an actuator between the legs. The Lyapunov function is defined as the square of the difference between the actual and nominal velocity of the unactuated stance leg at the midstance position (stance leg is normal to the ramp). The foot placement is controlled to ensure an exponential decay in the Lyapunov function. In essence, DCLF does foot placement control to regulate the midstance walking velocity between successive steps. The DCLF is able to enlarge the basin of attraction by an order of magnitude and to increase the average number of steps to failure by 2 orders of magnitude over passive dynamic walking. We compare DCLF with a one-step dead-beat controller (full correction of disturbance in a single step) and find that both controllers have similar robustness. The one-step dead-beat controller provides the fastest convergence to the limit cycle while using least amount of energy per unit step. However, the one-step dead-beat controller is more sensitive to modeling errors. We also compare the DCLF with an eigenvalue-based controller for the same rate of convergence. Both controllers yield identical robustness but the DCLF is more energy-efficient and requires lower maximum torque. Our results suggest that the DCLF controller with moderate rate of convergence provides good compromise between robustness, energy-efficiency, and sensitivity to modeling errors.

scholarly journals The Most Hazardous and Dangerous and Greatest Adventure on Which Man has Ever Embarked

2009 ◽  
Vol 131 (07) ◽  
pp. 28-35 ◽  
Author(s):  
Burton Dicht
Keyword(s):  
Soviet Union ◽  
The United States ◽  
Space Program ◽  
The Moon ◽  
High Profile ◽  
The Soviet Union ◽  
Space Race ◽  
The Face ◽  
One Step ◽  
Run Up

This report highlights on run-up to success, the American space program that had absorbed a series of high-profile embarrassments as the Soviet Union, with which the United States was competing in a so-called Space Race, seemed to remain one step ahead. To declare so publicly the goal to land a man on the moon before the end of the decade was to risk another humbling loss. At the time, the public spotlight shined on the face of the space program, the astronauts who had already become national heroes. One of the biggest issues to settle was the mission architecture—the steps through which spacecraft would be launched, landed on the moon, and returned safely. The engineers who designed the remarkable pieces of space hardware were only a part of the overall Apollo team. Thousands of engineers were involved in launch processing and monitoring the flights. In an era when computer systems were primitive compared to what we have today, constant communication between the astronauts and an army of engineers back in Houston was critical to ensure the safety of the astronauts as well as the success of the mission.

The 2 High Horizontal Man Sportsman Run-Up Final Step Sport Credits of Long Jump of Horizontal Speed Loss Reason

2010 ◽  
Vol 121-122 ◽  
pp. 728-732
Author(s):  
Hang Ying Lou ◽  
Guo Zheng Wang
Keyword(s):  
Horizontal Velocity ◽  
Knee Angle ◽  
Kinematic Parameters ◽  
The Third ◽  
The World ◽  
Long Jump ◽  
One Step ◽  
Run Up

This paper compared relevant kinematic parameters of the long jump elites from home and abroad, it analysed the reason why the reduction of the horizontal velocity in the last two steps in the world elites was 0.48m/s, while 0.68m/s in the domestic elites.The first reason the paper presented is to jump up too early which leads to the decrease of the velocity in the last two steps, the second reason is that the accelerative ability is weak and the length of one step varies, and the third reason is that the landing angle of the last step is small but it is big for the angle of departure. Apart from the above mentioned reasons, the paper also proposed another indispensible factor is that, the change of the knee angle in the last two steps which can help prevent the horizontal velocity from deceasing.

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