scholarly journals Biomechanical effects of the addition of a precision constraint on a collective load carriage task

2021 ◽  
Author(s):  
Nour Sghaier ◽  
Guillaume Fumery ◽  
Vincent Fourcassie ◽  
Nicolas Alain Turpin ◽  
Pierre Moretto
Keyword(s):  
Recovery Rate ◽  
Center Of Mass ◽  
Motor Task ◽  
Target Position ◽  
Load Carriage ◽  
Upper Limbs ◽  
Cognitive Components ◽  
Study Results ◽  
Accuracy Constraint ◽  
The Moment

Team lifting is a complex and collective motor task that possesses both motor and cognitive components. The purpose of this study was to investigate to what extent the biomechanics of a collective load carriage is affected when a dyad of individuals is performing a carrying task with an additional accuracy constraint. Ten dyads performed a first condition in which they collectively transported a load (CC), and a second one in which they transported the same load while maintaining a ball in a target position on its top (PC). The recovery rate, amplitude, and period of the center-of-mass (COM) trajectory were computed for the whole system (dyad + table = PACS). We analyzed the forces and moments exerted at each joint of the upper limbs of the subjects. We observed a decrease in the overall performance of the dyads when the Precision task was added, i.e., i) the velocity and amplitude of CoMPACS decreased by 1,7% and 5,8%, respectively, ii) inter-subject variability of the Moment-Cost-Function decreased by 95% and recovery rate decreased by 19,2% during PC. A kinetic synergy analysis showed that the subjects reorganized their coordination in the PC. Our results demonstrate that adding a precision task affects the economy of collective load carriage. Notwithstanding, the joint moments at the upper-limbs are better balanced and co-vary more across the paired subjects during the precision task. Our study results may find applications in domains such as Ergonomics, Robotics-developments, and Rehabilitation.

scholarly journals A biomechanical study of load carriage by two paired subjects in response to increased load mass

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillaume Fumery ◽  
Nicolas A. Turpin ◽  
Laetitia Claverie ◽  
Vincent Fourcassié ◽  
Pierre Moretto
Keyword(s):  
Recovery Rate ◽  
Energy Recovery ◽  
Mechanical Energy ◽  
Center Of Mass ◽  
Step Length ◽  
Biomechanical Study ◽  
Load Carriage ◽  
Joint Torque ◽  
Total Mechanical Energy ◽  
Load Mass

AbstractThe biomechanics of load carriage has been studied extensively with regards to single individuals, yet not so much with regards to collective transport. We investigated the biomechanics of walking in 10 paired individuals carrying a load that represented 20%, 30%, or 40% of the aggregated body-masses. We computed the energy recovery rate at the center of mass of the system consisting of the two individuals plus the carried load in order to test to what extent the pendulum-like behavior and the economy of the gait were affected. Joint torque was also computed to investigate the intra- and inter-subject strategies occurring in response to this. The ability of the subjects to move the whole system like a pendulum appeared rendered obvious through shortened step length and lowered vertical displacements at the center of mass of the system, while energy recovery rate and total mechanical energy remained constant. In parallel, an asymmetry of joint moment vertical amplitude and coupling among individuals in all pairs suggested the emergence of a leader/follower schema. Beyond the 30% threshold of increased load mass, the constraints at the joint level were balanced among individuals leading to a degraded pendulum-like behavior.

scholarly journals Mechanisms of control in hope jumping as a function of task constraint

2007 ◽  
Vol 2 (1) ◽  
pp. 31-39
Author(s):  
Luiz H. da Silva ◽  
Ana M. Pellegrini
Keyword(s):  
Relative Phase ◽  
Beat Frequency ◽  
Motor Task ◽  
Jump Height ◽  
Upper Limbs ◽  
Haptic Information ◽  
Task Constraint ◽  
Continuous Relative Phase ◽  
The Moment ◽  
Male University Students

Hope jumping is a motor task that can be performed in different ways and with ropes with different physical characteristics (weight, texture, and size). When the rope jump is performed with the rope being self controlled, relevant haptic information is available for the action control. In order to examine the adjustments made by the performer in rope jumping with ropes of different weight, eight male university students performed a sequence of 30 rope-jumping with ropes of 180, 255, and 330g. The rope was turn by the participant in a selfpaced mode. Such sequences were registered in video and the following variables were obtained: continuous relative phase, rope beat frequency, jump height, rope height, and temporal interval between the moment of the loss of the feet contact with the floor and the crossing of the rope under the feet. The results showed that only the rope frequency changed as a function of the rope weight, suggesting that the upper limbs when turning the rope are responsible for the adjustments in order to maintain the same level of performance.

MULTISTAGE ROCKET FLIGHT SIMULATION

2019 ◽  
pp. 105-107
Author(s):  
A. S. Busygin ◽  
А. V. Shumov
Keyword(s):  
State Vector ◽  
Center Of Mass ◽  
Flight Simulation ◽  
Continuous Change ◽  
Information Tools ◽  
The Earth ◽  
Proposed Model ◽  
Piecewise Continuous ◽  
The Moment ◽  
Simulated Object

The paper considers a method for simulating the flight of a multistage rocket in Matlab using Simulink software for control and guidance. The model takes into account the anisotropy of the gravity of the Earth, changes in the pressure and density of the atmosphere, piecewise continuous change of the center of mass and the moment of inertia of the rocket during the flight. Also, the proposed model allows you to work out various targeting options using both onboard and ground‑based information tools, to load information from the ground‑based radar, with imitation of «non‑ideality» of incoming target designations as a result of changes in the accuracy of determining coordinates and speeds, as well as signal fluctuations. It is stipulated that the design is variable not only by the number of steps, but also by their types. The calculations are implemented in a matrix form, which allows parallel operations in each step of processing a multidimensional state vector of the simulated object.

Efficient Treatment of Gyroscopic Bodies in the Recursive Solution of Multibody Dynamics Equations

2008 ◽  
Vol 3 (4) ◽  
Author(s):  
Martin M. Tong
Keyword(s):  
Center Of Mass ◽  
Solution Process ◽  
Body System ◽  
Efficient Treatment ◽  
Composite Body ◽  
Recursive Solution ◽  
System A ◽  
Principal Axes ◽  
Solution Methods ◽  
The Moment

This paper presents an efficient treatment of gyroscopic bodies in the recursive solution of the dynamics of an N-body system. The bodies of interest include the reaction wheels in satellites, wheels on a car, and flywheels in machines. More specifically, these bodies have diagonal inertia tensors. They spin about one of its principal axes, with the moment of inertia along the transverse axes identical. Their center of mass lies on the spin axis. Current recursive solution methods treat these bodies identically as any other body in the system. The proposition here is that a body with gyroscopic children can be collectively treated as a composite body in the recursive solution process. It will be shown that this proposition improves the recursive solution speed to the order(N−m) where m is the number of gyroscopic bodies in the system. A satellite with three reaction wheels is used to illustrate the proposition.

Motion Simulation of Key Components in a Package Machine

2012 ◽  
Vol 557-559 ◽  
pp. 2303-2306
Author(s):  
Shu Bin Kan
Keyword(s):  
Structural Parameters ◽  
Center Of Mass ◽  
Motion Simulation ◽  
Software Environment ◽  
Optimization Result ◽  
Adams Software ◽  
Motion Characteristic ◽  
The Moment ◽  
Selection Of

The motion characteristic of key components is a decisional factor to the working reliability and stability of a package machine. In this paper, the motion simulation of a key component is carried out in the ADAMS software environment. By analysis of the force, variance of the center-of-mass and the moment of the component, the mutation point in the motion is found, and then the structure is optimized by selection of different structural parameters. The optimization result shows a significant improvement for the reliability and stability of the whole machine.

scholarly journals Determination of Neuromuscular Control of the Upper Limbs in Children - Case Study

2020 ◽  
Vol 11 (4Sup1) ◽  
pp. 46-61
Author(s):  
Carmen-Magdalena Camenidis ◽  
◽  
Irina Băițel ◽  
Amalia Oatu ◽  
Octavian Amzulescu ◽  
...  
Keyword(s):  
Kinematic Chain ◽  
Neuromuscular Control ◽  
Female Gender ◽  
Upper Limbs ◽  
Motor Action ◽  
Muscle Groups ◽  
The Moment ◽  
The Right

The objective of this case study is to observe the existence of an anticipation mechanism at the muscle groups level of the upper limbs. We tried to highlighted this anticipation process by measuring the potential of surface electric for some muscle groups representing the kinematic chain on the right side, involved in the motor action of catching a basketball and a 3kg medicine ball with two hands to the chest. We conducted a case study of a 13-year-old child, female gender. As a measurement method, we used surface electromyography signals of the EMG Trigno Delsys wireless system with 16 electrodes. We determined the moment when the muscles come into action by increasing the potential of surface electric and the moment when the action of catching the ball takes place, using the information provided by the accelerometers incorporated in the sensors of the Delsys equipment used. Therefore, we obtained information about how different muscle groups come into action which helped us to get an idea of how the child's movement is structured. Based on results of accelerations and EMG signals acquired we have formulated conclusions regarding the neuromuscular control of the tested subject. We also planned for the future to test a larger group of participants in the study research of anticipation mechanism in children who do not practice any performance sports.

Balance Recovery based on Whole-Body Control using Joint Torque Feedback for Quadrupedal Robots

2021 ◽  
pp. 1-18
Author(s):  
Young Hun Lee ◽  
Hyunyong Lee ◽  
Hansol Kang ◽  
Jun Hyuk Lee ◽  
Ji Man Park ◽  
...  
Keyword(s):  
Force Feedback ◽  
Center Of Mass ◽  
Legged Locomotion ◽  
Joint Torque ◽  
Whole Body ◽  
External Disturbances ◽  
Feed Forward ◽  
The Moment ◽  
Joint Torque Feedback ◽  
Capture Point

Abstract In legged locomotion, the contact force between a robot and the ground plays a crucial role in balancing the robot. However, in quadrupedal robots, general whole-body controllers generate feed-forward force commands without considering the actual torque or force feedback. This paper presents a whole-body controller by using the actual joint torque measured from a torque sensor, which enables the quadrupedal robot to demonstrate both dynamic locomotion and reaction to external disturbances. We compute external joint torque using the measured joint torque and the robot's dynamics, and then transform this to the moment of the center of mass (CoM). Using the computed CoM moment, the moment-based impedance controller distributes a feed-forward force corresponding to the desired moment of the CoM to stabilize the robot's balance. Furthermore, to recover balance, the CoM motion is generated using capture point-based stepping control and zero moment point trajectory. The proposed whole-body controller was tested on a quadrupedal robot, named AiDIN-VI. Locomotive abilities on uneven terrains and slopes and in the presence of external disturbances are verified through experiments.

Member distortional buckling behaviour of hybrid double-I-box beams

2018 ◽  
Vol 45 (8) ◽  
pp. 605-622 ◽  
Author(s):  
M.S. Deepak ◽  
V.M. Shanthi
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Parametric Study ◽  
Flexural Rigidity ◽  
Numerical Study ◽  
Plate Thickness ◽  
Distortional Buckling ◽  
Study Results ◽  
Box Beams ◽  
The Moment

This paper compiles the experimental and finite-element parametric study on member distortional buckling behaviour of new built-up metal hybrid double-I-box beams (HDIBBs). The cross-section of this built-up beam is unique and looks similar to the shape of a double-I-box fabricated using four channel sections. The flange plates were provided with an intermediate stiffener. In these built-up beams there is more material in the flange portions far away from the horizontal centroidal axis of their cross-section. Hence, there is an increase in the flexural rigidity that enhances the moment capacity of the beam, under major axis bending. The geometry consists of torsionally rigid closed-box web portion that provides high resistance to minor axis lateral-buckling. The varying parameters considered were the ratio of yield stresses of the flange to the web steel plates, the ratio of breadth to the depth of the section, and the flange plate thickness. In the experimental programme, all the HDIBB members failed due to kinds of distortional buckling which was identified by web buckling and flange twist along edges. The results revealed that when flange plate slenderness increases there is a drop in the moment resistance capacity of the beams. The numerical study was performed using ABAQUS software. In comparison, there was good agreement between experimental and numerical results. The validated finite element models were further extended to perform parametric studies on ideal HDIBB models. Both the experimental and parametric study results were compared with the predicted strengths using effective width method equations specified in the Euro code standards EN 3-1-3. It was found that the current Euro code design rules slightly over-estimate the distortional buckling resistance capacity of closed form built-up cold-formed steel members. A new design equation was formulated and recommended for estimating the reduction in distortional buckling moment resistance capacity for HDIBBs.

Correction of motor coordination abilities in acute cerebral circulation defect with the use of physical rehabilitation

2020 ◽  
pp. 91-97
Author(s):  
Andrey P. Popov ◽  
Valentina I. Syutina
Keyword(s):  
Muscle Strength ◽  
Cerebral Circulation ◽  
Motor Coordination ◽  
Center Of Mass ◽  
Recovery Period ◽  
Standing Position ◽  
Physical Rehabilitation ◽  
Early Recovery ◽  
Leading Role ◽  
Study Results

Due to the high frequency of strokes in the Russian Federation, leading to disability, loss of efficiency and loss of household autonomy, the development of methods of patients rehabilitation who have suffered acute cerebral circulation disorder is of high importance. The consequences of this condition is characterized by a number of syndromes, among which the leading role in reducing the motor activity of patients and limiting their ability to self-service, is hemiparesis, accompanied by a decrease in voluntary muscle strength in the affected limbs. We present the study results of computer stabilometry indicators as a means of assessing the ability to maintain static equilibrium in a standing position and control the oscillations of the general center of mass. We also present the evaluation results of arbitrary muscle strength of the affected limbs in patients with the consequences of acute cerebral circulation defect in the early recovery period. These studies were carried out as part of an experiment to assess the effectiveness of the multisensory stimulation technique, which is based on the combination of a number of stimulating and corrective effects in combination with physical exercises in closed and open kinematic circuits. The results of the study confirm the effectiveness of the developed method of physical rehabilitation.

Research of Baseball’s Best Batting Position Changes with the Selection of Material of Baseball

2013 ◽  
Vol 690-693 ◽  
pp. 1826-1830
Author(s):  
Li Ping Du ◽  
Wu Li ◽  
Wen Sheng Han
Keyword(s):  
Major League Baseball ◽  
Center Of Mass ◽  
Original Material ◽  
Sweet Spot ◽  
Collision Model ◽  
Exit Speed ◽  
The Moment ◽  
Definition Of ◽  
Selection Of ◽  
Parameters Calculation

From the aspect of the fastest exit speed of the ball and through the collision model of mechanics, we analyzed the best hitting point which results in the fastest exit speed of the ball and the change of the best hitting point. Based on this model, we gave a very practical definition of the sweet spot, and we also found out the effect of the baseball bat’s material on the sweet spot. The distances from the best hitting point to the end of the baseball bat result from the three different materials, which are the bat’s original material, aluminum and the corked material. Through the sensitivity analysis, three parameters affecting the hitting position resulting in the ball’s fastest exit speed are the weight of the bat, the center of mass and the moment-of-inertia. In the process of the three parameters’ calculation, the infinitesimal method is used. As can be found out that the length of the sweet spot results from the corked and the aluminum are much longer than results from the original material. The longer the length of sweet spot, the possibility that the hitter hits the fast ball is higher. Also ball hit by the aluminum bat is faster than that hit by the bat made out of the original material. The above analysis can explain that why the aluminum bat and corked bat are prohibited by Major League Baseball

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