Optimization of the centre of mass position of a racing motorcycle in dry and wet track by means of the “Optimal Maneuver Method”

ABSTRACTThe role of trunk orientation during uneven running is not well understood. This study compared the running mechanics during the approach step to and the step down for a 10 cm expected drop, positioned halfway through a 15 m runway, with that of the level step in 12 participants at a speed of 3.5 m s−1 while maintaining self-selected (17.7±4.2 deg; mean±s.d.), posterior (1.8±7.4 deg) and anterior (26.6±5.6 deg) trunk leans from the vertical. Our findings reveal that the global (i.e. the spring-mass model dynamics and centre-of-mass height) and local (i.e. knee and ankle kinematics and kinetics) biomechanical adjustments during uneven running are specific to the step nature and trunk posture. Unlike the anterior-leaning posture, running with a posterior trunk lean is characterized by increases in leg angle, leg compression, knee flexion angle and moment, resulting in a stiffer knee and a more compliant spring-leg compared with the self-selected condition. In the approach step versus the level step, reductions in leg length and stiffness through the ankle stiffness yield lower leg force and centre-of-mass position. Contrariwise, significant increases in leg length, angle and force, and ankle moment, reflect in a higher centre-of-mass position during the step down. Plus, ankle stiffness significantly decreases, owing to a substantially increased leg compression. Overall, the step down appears to be dominated by centre-of-mass height changes, regardless of having a trunk lean. Observed adjustments during uneven running can be attributed to anticipation of changes to running posture and height. These findings highlight the role of trunk posture in human perturbed locomotion relevant for the design and development of exoskeleton or humanoid bipedal robots.

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Limit Steady State Vehicle Handling

Proceedings of the Institution of Mechanical Engineers Part D Transport Engineering ◽

10.1243/pime_proc_1987_201_187_02 ◽

1987 ◽

Vol 201 (4) ◽

pp. 281-291 ◽

Cited By ~ 5

Author(s):

J C Dixon

Keyword(s):

Steady State ◽

Load Transfer ◽

Limit State ◽

Lateral Acceleration ◽

Design Parameters ◽

Centre Of Mass ◽

Vehicle Handling ◽

Specific Proposal ◽

Turning Radius ◽

Mass Position

Previously, limit steady state handling has always been restricted to the qualitative statement that a vehicle has final understeer or final oversteer; it cannot be analysed by the conventional understeer gradient concept. A specific proposal is made for quantification of final understeer or oversteer. This is called the understeer number, and is defned by Nu = (ArAf)-1, where Af and Ar are the lateral acceleration capabilities of the front and rear axles. Thus Nu is non-dimensional, is zero for a notional final neutral vehicle, positive for final understeer and negative for final oversteer. A typical value is 0.150 (rear drive) or 0.220 (front). The various design parameters that influence the understeer number are investigated, and equations are obtained and quantified, including centre of mass position, lateral load transfer distribution, longitudinal load transfer, traction, the components of aerodynamic forces and moments, the effect of non-free differentials and the effect of load increments. The effect of turning radius and slopes is also investigated. Thus the limit state of handling is subject to a quantitative assessment, showing the degree of a vehicle's commitment to final understeer or oversteer.

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LONG JUMP: MECHANICAL AND ENERGETIC ASPECTS

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519404001120 ◽

2004 ◽

Vol 04 (04) ◽

pp. 535-557 ◽

Cited By ~ 1

Author(s):

T. K. KARALIS

Keyword(s):

Contact Point ◽

Reaction Force ◽

Vertical Component ◽

Centre Of Mass ◽

Force Vector ◽

Direct Measurements ◽

Long Jump ◽

The Mean ◽

Vector Formula ◽

Mass Position

The use of variation techniques is applied to investigate jumper's posture at take-off, resulting in maximum distance of jump. Explicit expressions have been derived between: (i) the take-off angle ϕT (formed by the line connecting the contact point of the leg driving the jump with the ground to the centre of mass position and the horizontal), (ii) the ratio [Formula: see text] of the mean vertical component of the ground reaction force vector to athlete's weight at take-off, (iii) the time spent for the mid-support/take-off phase TT, and (iv) the change in the vertical component of the displacement of the centre of mass compared with the take-off foot ΔyT, measured between two extreme postures, i.e. the mid-support and the take-off phase. The method is illustrated by calculating the state vector [Formula: see text] at take-off, in connection with the take-off angle ϕT. The results are compared to direct measurements from real long jumps.

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A fast methodology to determine the characteristics of thousands of grains using three-dimensional X-ray diffraction. I. Overlapping diffraction peaks and parameters of the experimental setup

Journal of Applied Crystallography ◽

10.1107/s0021889812025563 ◽

2012 ◽

Vol 45 (4) ◽

pp. 693-704 ◽

Cited By ~ 39

Author(s):

Hemant Sharma ◽

Richard M. Huizenga ◽

S. Erik Offerman

Keyword(s):

Data Analysis ◽

Three Dimensional ◽

Experimental Setup ◽

Centre Of Mass ◽

X Ray Diffraction ◽

X Ray ◽

Overlapping Peaks ◽

Diffraction Peaks ◽

Mass Position

A data-analysis methodology is presented for the characterization of three-dimensional microstructures of polycrystalline materials from data acquired using three-dimensional X-ray diffraction (3DXRD). The method is developed for 3DXRD microscopy using a far-field detector and yields information about the centre-of-mass position, crystallographic orientation, volume and strain state for thousands of grains. This first part deals with pre-processing of the diffraction data for input into the algorithms presented in the second part [Sharma, Huizenga & Offerman (2012).J. Appl. Cryst.45, 705–718] for determination of the grain characteristics. An algorithm is presented for accurate identification of overlapping diffraction peaks from X-ray diffraction images, which has been an issue limiting the accuracy of experiments of this type. The algorithm works in two stages, namely the identification of overlapping peaks using a seeded watershed algorithm, and then the fitting of the peaks with a pseudo-Voigt shape function to yield an accurate centre-of-mass position and integrated intensity for the peaks. Regions consisting of up to six overlapping peaks can be successfully fitted. Two simulations and an experiment are used to verify the results of the algorithms. An example of the processing of diffraction images acquired in a 3DXRD experiment with a sample consisting of more than 1600 grains is shown. Furthermore, a procedure for the determination of the parameters of the experimental setup (global parameters) without the need for a calibration sample is presented and validated using simulations. This is immensely beneficial for simplifying experiments and the subsequent data analysis.

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First Paper: Imperfections in Vacuum Remelted Precision Steel Balls Which Affect Ball Race Performance

Proceedings of the Institution of Mechanical Engineers ◽

10.1243/pime_proc_1970_185_043_02 ◽

1970 ◽

Vol 185 (1) ◽

pp. 353-365

Author(s):

D. J. Haines

Keyword(s):

Centre Of Mass ◽

Ball Surface ◽

Steel Balls ◽

Race Performance ◽

Mass Position ◽

Ball Motion

In a study of ball motion in an angular contact ball race the author found that precision steel balls having their centre of mass displaced from the true geometric centre of the ball show tendencies to run in a ‘heavy end outwards’ condition resulting in preferential wear of parts of the ball surface. Three techniques are described which permit the sorting of balls and the elimination of those which limit race life due to errors in ball sphericity and errors in centre of mass position.

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The system of airplane centre-of-mass position-finding in the flight mode

Electronics and Control Systems ◽

10.18372/1990-5548.30.919 ◽

2011 ◽

Vol 4 (30) ◽

Author(s):

А.П. Козлов ◽

О.В. Мельников ◽

Ю.М. Кеменяш

Keyword(s):

Centre Of Mass ◽

Flight Mode ◽

Mass Position

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Estimation of the Centre of Mass From Motion Capture and Force Plate Recordings: A Study on the Elderly

Applied Bionics and Biomechanics ◽

10.1155/2011/123246 ◽

2011 ◽

Vol 8 (1) ◽

pp. 67-84 ◽

Cited By ~ 19

Author(s):

S. Cotton ◽

M. Vanoncini ◽

P. Fraisse ◽

N. Ramdani ◽

E. Demircan ◽

...

Keyword(s):

Motion Capture ◽

Force Plate ◽

The Elderly ◽

The Body ◽

Estimation Methods ◽

Centre Of Mass ◽

Joint Angles ◽

Biomechanical Models ◽

The Subject ◽

Mass Position

The estimation of the centre of mass position in humans is usually based on biomechanical models developed from anthropometric tables. This method can potentially introduce errors in studies involving elderly people, since the ageing process is typically associated with a modification of the distribution of the body mass. In this paper, an alternative technique is proposed, and evaluated with an experimental study on 9 elderly volunteers. The technique is based on a virtual chain, identified from experimental data and locating the subject's centre of mass. Its configuration defines the location of the centre of mass, and is a function of the anatomical joint angles measured on the subject. This method is a valuable investigation tool in the field of geronto-technology, since it overcomes some of the problems encountered with other CoM estimation methods.

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Development of Machine Learning Algorithms for the Determination of the Centre of Mass

Symmetry ◽

10.3390/sym13030401 ◽

2021 ◽

Vol 13 (3) ◽

pp. 401

Author(s):

Danilo D’Andrea ◽

Filippo Cucinotta ◽

Flavio Farroni ◽

Giacomo Risitano ◽

Dario Santonocito ◽

...

Keyword(s):

Human Body ◽

Machine Learning Algorithms ◽

Vertical Position ◽

Centre Of Mass ◽

Wii Balance Board ◽

Almost All ◽

Mass Position ◽

Balance Board ◽

Capture Technique

The study of the human body and its movements is still a matter of great interest today. Most of these issues have as their fulcrum the study of the balance characteristics of the human body and the determination of its Centre of Mass. In sports, a lot of attention is paid to improving and analysing the athlete's performance. Almost all the techniques for determining the Centre of Mass make use of special sensors, which allow determining the physical magnitudes related to the different movements made by athletes. In this paper, a markerless method for determining the Centre of Mass of a subject has been studied, comparing it with a direct widely validated equipment such as the Wii Balance Board, which allows determining the coordinates of the Centre of Pressure. The Motion Capture technique was applied with the OpenPose software, a Computer Vision method boosted with the use of Convolution Neural Networks. Ten quasi-static analyses have been carried out. The results have shown an error of the Centre of Mass position, compared to that obtained from the Wii Balance Board, which has been considered acceptable given the complexity of the analysis. Furthermore, this method, despite the traditional methods based on the use of balances, can be used also for prediction of the vertical position of the Centre of Mass.

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Countermovement jump performance in elite male and female sprinters and high jumpers

Proceedings of the Institution of Mechanical Engineers Part P Journal of Sports Engineering and Technology ◽

10.1177/1754337120971436 ◽

2020 ◽

pp. 175433712097143

Author(s):

Lydia Kate Philpott ◽

Stephanie E Forrester ◽

Katherine AJ van Lopik ◽

Steven Hayward ◽

Paul P Conway ◽

...

Keyword(s):

Time Series ◽

Peak Power ◽

Female Athletes ◽

Strongly Correlated ◽

Jump Height ◽

Centre Of Mass ◽

Time Data ◽

Jump Performance ◽

Male And Female ◽

Mass Position

Countermovement jumps (CMJs) are widely used in athlete training, performance monitoring and research as an indicator of power output. Despite extensive scientific research on CMJs, data for elite track and field athletes is limited, particularly for non-sprint events and female athletes. The purpose of this study was threefold: (i) to compare CMJ performance between elite sprinters and high jumpers; (ii) to compare CMJ performance between elite male and female athletes in these two events; and (iii) to determine which CMJ take-off parameters correlated most strongly with jump height. Twenty-seven elite athletes (sprinters: nine male and seven female; high jumpers: five male and six female) completed three maximal CMJs. Jump height and take-off phase parameters were obtained from the force–time data and compared between groups; additionally, time series comparisons were performed on the force, power and displacement data. There was no difference in jump height or any of the take-off parameters between the sprinters and high jumpers; however, the time series analysis indicated that the sprinters maintained a lower centre of mass position during the latter concentric phase. The male athletes jumped higher than the female athletes (by 10.0 cm or 24.2%; p < 0.001) with significantly greater body weight normalised peak power (17.9%, p = 0.002) and significantly shorter eccentric time (17.4%, p = 0.035). Jump height was most strongly correlated with peak power. In addition, jump height was also strongly correlated with positive impulse and both minimum and mean concentric centre of mass position. These results support the importance of accounting for event and gender when investigating CMJ performance.

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