Mechanics of running under simulated low gravity

1991 ◽  
Vol 71 (3) ◽  
pp. 863-870 ◽  
Author(s):  
J. P. He ◽  
R. Kram ◽  
T. A. McMahon
Keyword(s):  
Normal Gravity ◽  
Human Subjects ◽  
Center Of Mass ◽  
The Body ◽  
Vertical Force ◽  
Low Gravity ◽  
Vertical Stiffness ◽  
Mass Spring Model ◽  
Linear Spring ◽  
Mass Spring

Using a linear mass-spring model of the body and leg (T. A. McMahon and G. C. Cheng. J. Biomech. 23: 65–78, 1990), we present experimental observations of human running under simulated low gravity and an analysis of these experiments. The purpose of the study was to investigate how the spring properties of the leg are adjusted to different levels of gravity. We hypothesized that leg spring stiffness would not change under simulated low-gravity conditions. To simulate low gravity, a nearly constant vertical force was applied to human subjects via a bicycle seat. The force was obtained by stretching long steel springs via a hand-operated winch. Subjects ran on a motorized treadmill that had been modified to include a force platform under the tread. Four subjects ran at one speed (3.0 m/s) under conditions of normal gravity and six simulated fractions of normal gravity from 0.2 to 0.7 G. For comparison, subjects also ran under normal gravity at five speeds from 2.0 to 6.0 m/s. Two basic principles emerged from all comparisons: both the stiffness of the leg, considered as a linear spring, and the vertical excursion of the center of mass during the flight phase did not change with forward speed or gravity. With these results as inputs, the mathematical model is able to account correctly for many of the changes in dynamic parameters that do take place, including the increasing vertical stiffness with speed at normal gravity and the decreasing peak force observed under conditions simulating low gravity.

Effect of Added Mass on Human Unipedal Hopping

2002 ◽  
Vol 94 (3) ◽  
pp. 834-840 ◽  
Author(s):  
Gary P. Austin ◽  
Gladys E. Garrett ◽  
David Tiberio
Keyword(s):  
Body Mass ◽  
Vertical Force ◽  
Vertical Stiffness ◽  
Mass Spring Model ◽  
Simple Mass ◽  
Neuromuscular Assessment ◽  
Hip Flexion ◽  
Mass Spring ◽  
And Training ◽  
Insight Into

Although hopping is considered a children's activity, it can be used to provide insight into the neuromuscular and biomechanical performance of adults. This study investigated whether mass added during unipedal hopping altered the vertical stiffness, hopping period, and angular kinematics of the lower extremity of adults. Measures of two-dimensional kinematics and vertical force were made from 10 healthy men during hopping at a preferred period under three conditions: Body Mass, Body Mass + 10%, and Body Mass + 20%. Adding mass significantly increased hopping period and hip flexion without significantly affecting vertical stiffness, ankle dorsiflexion, or knee flexion. Overall, the findings agreed with predictions based on a simple-mass spring model. The results indicate unique kinetic and kinematic responses to increased mass during hopping may have potential application in neuromuscular assessment and training for the lower extremities.

scholarly journals Estimates of Running Ground Reaction Force Parameters from Motion Analysis

2017 ◽  
Vol 33 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Gaspare Pavei ◽  
Elena Seminati ◽  
Jorge L.L. Storniolo ◽  
Leonardo A. Peyré-Tartaruga
Keyword(s):  
Motion Analysis ◽  
Ground Reaction Force ◽  
Center Of Mass ◽  
Reaction Force ◽  
The Body ◽  
Vertical Force ◽  
Vertical Stiffness ◽  
Leg Stiffness ◽  
Force Peak ◽  
Body Center

We compared running mechanics parameters determined from ground reaction force (GRF) measurements with estimated forces obtained from double differentiation of kinematic (K) data from motion analysis in a broad spectrum of running speeds (1.94–5.56 m⋅s–1). Data were collected through a force-instrumented treadmill and compared at different sampling frequencies (900 and 300 Hz for GRF, 300 and 100 Hz for K). Vertical force peak, shape, and impulse were similar between K methods and GRF. Contact time, flight time, and vertical stiffness (kvert) obtained from K showed the same trend as GRF with differences < 5%, whereas leg stiffness (kleg) was not correctly computed by kinematics. The results revealed that the main vertical GRF parameters can be computed by the double differentiation of the body center of mass properly calculated by motion analysis. The present model provides an alternative accessible method for determining temporal and kinetic parameters of running without an instrumented treadmill.

scholarly journals Thrust Vector Control of an Upper-Stage Rocket with Multiple Propellant Slosh Modes

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Jaime Rubio Hervas ◽  
Mahmut Reyhanoglu
Keyword(s):  
Vector Control ◽  
Center Of Mass ◽  
Nonlinear Feedback ◽  
Thrust Vector Control ◽  
Engine Thrust ◽  
Mass Spring Model ◽  
Upper Stage ◽  
Thrust Vector ◽  
Mass Spring ◽  
Main Engine

The thrust vector control problem for an upper-stage rocket with propellant slosh dynamics is considered. The control inputs are defined by the gimbal deflection angle of a main engine and a pitching moment about the center of mass of the spacecraft. The rocket acceleration due to the main engine thrust is assumed to be large enough so that surface tension forces do not significantly affect the propellant motion during main engine burns. A multi-mass-spring model of the sloshing fuel is introduced to represent the prominent sloshing modes. A nonlinear feedback controller is designed to control the translational velocity vector and the attitude of the spacecraft, while suppressing the sloshing modes. The effectiveness of the controller is illustrated through a simulation example.

Effects of Fatigue on Running Mechanics: Spring-Mass Behavior in Recreational Runners After 60 Seconds of Countermovement Jumps

2015 ◽  
Vol 31 (6) ◽  
pp. 445-451 ◽  
Author(s):  
Gabriela Fischer ◽  
Jorge L.L. Storniolo ◽  
Leonardo A. Peyré-Tartaruga
Keyword(s):  
Center Of Mass ◽  
Force Plate ◽  
Vertical Displacement ◽  
Step Length ◽  
Vertical Force ◽  
Step Frequency ◽  
Mass Model ◽  
Vertical Stiffness ◽  
Recreational Runners ◽  
Running Mechanics

The purpose of this study was to investigate the effects of acute fatigue on spring-mass model (SMM) parameters among recreational runners at different speeds. Eleven participants (5 males and 6 females) performed running trials at slower, self-selected, and faster speeds on an indoor track before and after performing a fatigue protocol (60 s of countermovement jumps). Maximal vertical force (Fmax), impact peak force (Fpeak), loading rate (LR), contact time (Tc), aerial time (Ta), step frequency (SF), step length (SL), maximal vertical displacement of the center of mass (ΔZ), vertical stiffness (Kvert), and leg work (Wleg) were measured using a force plate integrated into the track. A significant reduction (–43.1 ± 8.6%; P < .05) in mechanical power during jumps indicated that the subjects became fatigued. The results showed that under fatigue conditions, the runners adjusted their running mechanics at slower (≈2.7 ms–1; ΔZ –12% and SF +3.9%; P < .05), self-selected (≈3.3 ms–1; SF +3%, SL –6.8%, Ta –16%, and Fmax –3.3%; P < .05), and faster (≈3.6 ms–1 SL –6.9%, Ta –14% and Fpeak –9.8%; P < .05) speeds without significantly altering Kvert (P > .05). During constant running, the previous 60 s of maximal vertical jumps induced mechanical adjustments in the spatiotemporal parameters without altering Kvert.

NONLINEAR RESPONSE OF THE MASS-SPRING MODEL WITH NONSMOOTH STIFFNESS

2012 ◽  
Vol 22 (01) ◽  
pp. 1250006 ◽  
Author(s):  
GRZEGORZ LITAK ◽  
JESÚS M. SEOANE ◽  
SAMUEL ZAMBRANO ◽  
MIGUEL A. F. SANJUÁN
Keyword(s):  
Nonlinear Response ◽  
Homoclinic Orbits ◽  
Prototype Model ◽  
Spring Model ◽  
Mass Spring Model ◽  
Nonlinear Potential ◽  
Melnikov Analysis ◽  
Linear Spring ◽  
Mass Spring

In this paper, we study the nonlinear response of the nonlinear mass-spring model with nonsmooth stiffness. For this purpose, we take as prototype model, a system that consists of the double-well smooth potential with an additional spring component acting on the system only for large enough displacement. We focus our study on the analysis of the homoclinic orbits for such nonlinear potential for which we observe the appearance of chaotic motion in the presence of damping effects and an external harmonic force, analyzing the crucial role of the linear spring in the dynamics of our system. The results are shown by using both the Melnikov analysis and numerical simulations. We expect our work to have implications on problems concerning the suspension of vehicles, among others.

A treadmill-mounted force platform

1989 ◽  
Vol 67 (4) ◽  
pp. 1692-1698 ◽  
Author(s):  
R. Kram ◽  
A. J. Powell
Keyword(s):  
Full Range ◽  
Center Of Mass ◽  
Reaction Force ◽  
Vertical Displacement ◽  
The Body ◽  
Force Platform ◽  
Vertical Force ◽  
Vertical Ground Reaction Force ◽  
Contact Phase ◽  
Frictional Forces

Muscle, bone, and tendon forces; the movement of the center of mass, and the spring properties of the body during terrestrial locomotion can be measured using ground-mounted force platforms. These measurements have been extremely time consuming because of the difficulty in obtaining repeatable constant speed trials (particularly with animals). We have overcome this difficulty by mounting a force platform directly under the belt of a motorized treadmill. With this arrangement, vertical force can be recorded from an unlimited number of successive ground contacts in a much shorter time. With this treadmill-mounted force platform it is possible to accurately make the following measurements over the full range of steady speeds and under various perturbations of normal gait: 1) vertical ground reaction force over the course of the contact phase; 2) peak forces in bone, muscle, and tendon; 3) the vertical displacement of the center of mass; and 4) contact time for the limbs. In our treadmill-force platform design, belt forces and frictional forces cause no measurable cross-talk problem. Natural frequency (160 Hz), nonlinearity (less than 5%), and position independence (less than 2%) are all quite acceptable. Motor-caused vibrations are greater than 150 Hz and thus can be easily filtered.

Reaching to Multiple Targets When Standing: The Spatial Organization of Feedforward Postural Adjustments

2009 ◽  
Vol 101 (4) ◽  
pp. 2120-2133 ◽  
Author(s):  
Julia A. Leonard ◽  
Ryan H. Brown ◽  
Paul J. Stapley
Keyword(s):  
Spatial Organization ◽  
Human Subjects ◽  
Body Position ◽  
Center Of Mass ◽  
The Body ◽  
Reaching Movements ◽  
Muscle Synergies ◽  
Electromyographic Activity ◽  
Postural Adjustments ◽  
Arm Reaching

We examined the spatial organization of feedforward postural adjustments produced prior to and during voluntary arm reaching movements executed while standing. We sought to investigate whether the activity of postural muscles before and during reaching was directionally tuned and whether a strategy of horizontal force constraint could be observed. To this end, eight human subjects executed self-paced reach-to-point movements on the random illumination of one of 13 light targets placed within a 180° array centered along the midline of the body. Analysis was divided into two periods: a first corresponding to the 250 ms preceding the onset of the reaching movements (termed pPA period) and a second 250-ms period immediately preceding target attainment (the aPA period). For both periods, electromyographic activity of the lower limb muscles revealed a clear directional tuning, with groups of muscles being activated for similar directions of reach. Analysis of horizontal ground reaction forces supported the existence of a force constraint strategy only for the pPA period, however, with those in the aPA period being more widely dispersed. We suggest that the strategy adopted for feedforward pPAs is one where the tuned muscle synergies constrain the forces diagonally away from the center of mass (CoM) to move it within the support base. However, the need to control for final finger and body position for each target during the aPA phase resulted in a distribution of vectors across reaching directions. Overall, our results would support the idea that endpoint limb force during postural tasks depends on the use of functional muscle synergies, which are used to displace the CoM or decelerate the body at the end of the reach.

CENTER OF MASS-BASED ADMITTANCE CONTROL FOR MULTI-LEGGED ROBOT WALKING ON THE BOTTOM OF OCEAN

2015 ◽  
Vol 74 (9) ◽  
Author(s):  
Addie Irawan ◽  
Md. Moktadir Alam ◽  
Yee Yin Tan ◽  
Mohd Rizal Arshad
Keyword(s):  
Buoyancy Force ◽  
Center Of Mass ◽  
The Body ◽  
Total Force ◽  
Vertical Force ◽  
Hexapod Robot ◽  
Admittance Control ◽  
Foot Placement ◽  
Robot Locomotion ◽  
Foot Motion

This paper presents a proposed adaptive admittance control that is derived based on Center of Mass (CoM) of the hexapod robot designed for walking on the bottom of water or seabed. The study has been carried out by modeling the buoyancy force following the restoration force to achieve the drowning level according to the Archimedes’ principle. The restoration force needs to be positive in order to ensure robot locomotion is not affected by buoyancy factor. As a solution to regulate this force, admittance control has been derived based on the total force of foot placement to determine CoM of the robot while walking. This admittance control is designed according to a model of a real-time based 4-degree of freedom (DoF) leg configuration of a hexapod robot that able to perform hexapod-to-quadruped transformation. The analysis focuses on the robot walking in both configuration modes; hexapod and quadruped; with both tripod and traverse-trot walking pattern respectively. The verification is done on the vertical foot motion of the leg and the body mass coordination movement for each walking simulation. The results show that the proposed admittance control is able to regulate the force restoration factor by making vertical force on each foot sufficiently large (sufficient foot placement) compared to the buoyancy force of the ocean, thus performing stable locomotion for both hexapod and quadruped mode.

scholarly journals Biomechanics of Flight in Neotropical Butterflies: Aerodynamics and Mechanical Power Requirements

1991 ◽  
Vol 159 (1) ◽  
pp. 335-357 ◽  
Author(s):  
ROBERT DUDLEY
Keyword(s):  
Energy Storage ◽  
Elastic Energy ◽  
Center Of Mass ◽  
The Body ◽  
Mechanical Power ◽  
Morphological Data ◽  
Vertical Force ◽  
Forward Flight ◽  
Insect Wings ◽  
Inertial Energy

A quasi-steady aerodynamic analysis of forward flight was performed on 15 species of neotropical butterflies for which kinematic and morphological data were available. Mean lift coefficients required for flight typically exceeded maximum values obtained on insect wings under conditions of steady flow, thereby implicating unsteady aerodynamic mechanisms even during fast forward flight of some butterflies. The downstroke produced vertical forces on average 18% in excess of those necessary to support the body weight through the wingbeat, while the upstroke contributed minimal or negative vertical force. Estimated effective angles of incidence (αT of the wings averaged 39° during the downstroke and −22° during the upstroke; spanwise variation in αT was greater than the average difference between half-strokes. Total mechanical power requirements of forward flight averaged 12.5 W kg−1, for the case of perfect elastic storage of whig inertial energy, and 20.2 W kg−1, assuming zero elastic energy storage. Energetic costs of the erratic trajectories during forward flight increased mechanical power requirements by an average of 43%, assuming perfect elastic storage. Fluctuations in horizontal kinetic energy of the center of mass were principally responsible for this dramatic increase. When comparing different species, total mechanical power increased linearly with forward airspeed (assuming perfect elastic energy storage of inertial energy) and scaled with mass0.26 If no elastic energy storage was assumed, mechanical power was independent of airspeed and was proportional to mass0.36. Estimated metabolic rates during flight averaged 22 and 36 ml O2 g−1 h−1, for the cases of perfect and zero elastic storage, respectively. Note: Mailing address: Smithsonian Tropical Research Institute, APO Miami, FL 34002, USA.

scholarly journals Real-Time Cloth Simulation for Hula Costume CAD Development

2021 ◽  
Vol 10 (3) ◽  
pp. 85-89
Author(s):  
Taketo Kamasaka ◽  
◽  
Kodai Miyamoto ◽  
Makoto Sakamoto ◽  
◽  
...  
Keyword(s):  
High Performance ◽  
Euler Method ◽  
The Body ◽  
Spring Model ◽  
Kutta Method ◽  
Runge Kutta Method ◽  
Mass Spring Model ◽  
Simulation Results ◽  
Mass Spring ◽  
Very High

In recent years, 3D computer graphics (3DCG) technology has been applied in various fields such as AR technology, VR technology, movies, games, and virtual fitting of clothes. Among them, there is the problem of contact between clothing and other objects (such as the body). In this paper, we focus on that problem. Since this research is part of the development of CAD for the design of hula costumes, and since we assume that the users of the CAD will have PCs with not very high performance, we took an approach that does not require a large amount of computation. As a representation of the cloth, we used a mass-spring model in which springs and mass points are connected in a grid. We also compared how the three methods of calculating position and velocity, Euler method, FB Euler method, and Runge-Kutta method, affect the simulation results.

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