Mohd Hasnun Arif Hassan

A Low Cost 3D Foot Scanner for Custom-Made Sports Shoes

Conventional methods to obtain foot anthropometry for custom made sports shoes using anthropometer, callipers and measuring tapes are inaccurate due to the complex anatomy and curvature of the instep, foot arc and related joints. They lead to poor repeatability and large variances, particularly when measurements are taken of different people. Measurements from 3D model have been claimed as a perfect tool to obtain anthropometric data. However a commercial 3D foot scanner to create a 3D foot model can be very costly. In this paper we propose a low cost 3D foot scanner system by integrating available image capture technology such as the Kinect®, appropriate 3D scanning software and a foot scanner rig. An experiment was conducted to compare the anthropometry data taken using conventional method and from the 3D model. The differences recorded for all regions were found to be less than 5%, suggesting that the 3D model produced by this method is accurate. The use of 3D scanner has also decreased the measurement duration, thus increasing the repeatability whilst decreasing human errors that normally occur during the measurement process.

A reaction-force-validated soccer ball finite element model

The soccer ball is one of the important pieces of equipment in the game of soccer. It undergoes various forms of impact during the game. In order to numerically investigate the occasions of ball impact such as soccer heading, a validated finite element model of a soccer ball is required. Therefore, a model was developed incorporating material properties obtained from literature. To ensure the accuracy of the model, it was validated against an established soccer ball model and experimental data of the coefficient of restitution, contact time, longitudinal deformation and reaction force. In addition, a parametric study of the mesh density was also performed to determine the optimal number of elements. The developed soccer ball model was found to be in a good agreement with the literature and experimental data. This suggests that, the soccer ball model is capable of replicating the impacts of interest. This article details the development of the model and the validation processes.

Predicting brain acceleration during heading of soccer ball

There has been a long debate whether purposeful heading could cause harm to the brain. Studies have shown that repetitive heading could lead to degeneration of brain cells, which is similarly found in patients with mild traumatic brain injury. A two-degree of freedom linear mathematical model was developed to study the impact of soccer ball to the brain during ball-to-head impact in soccer. From the model, the acceleration of the brain upon impact can be obtained. The model is a mass-spring-damper system, in which the skull is modelled as a mass and the neck is modelled as a spring-damper system. The brain is a mass with suspension characteristics that are also defined by a spring and a damper. The model was validated by experiment, in which a ball was dropped from different heights onto an instrumented dummy skull. The validation shows that the results obtained from the model are in a good agreement with the brain acceleration measured from the experiment. This findings show that a simple linear mathematical model can be useful in giving a preliminary insight on what human brain endures during a ball-to-head impact.

The Efficacy of Impact-Absorbing Materials during Collision with a Soccer Ball

The uniqueness of soccer is that the players are allowed to use their head to pass the ball to a teammate of even try to score goal. Studies have shown that heading in soccer might be dangerous to the brain and could lead to brain trauma. There are headgears available for soccer players to protect their head, but studies have proven that currently available headgears are ineffective in reducing the impact caused by a soccer ball. The objective of this study is to test the efficacy of six different types of impact-absorbing materials in reducing the linear impact force from a soccer ball. The soccer ball was dropped from the height of 2.3 m onto a force platform to measure the impact force. A high-speed camera is used to record the motion and the impact duration, and then the coefficient of restitution for each impact was determined. Polyurethane (PU) comb-gel was found to be the most effective material in reducing the peak impact force and impulse compared with other materials. The reduction in peak force was associated with longer impact duration between the soccer ball and the PU comb-gel. However, the coefficient of restitution was reduced by 21.7%, implying that using the gel alone will reduce the speed of the ball after heading, thus reducing the performance of a player wearing it. A combination of PU gel and another stiffer material is suggested and the effectiveness of the composite will be the subject of future investigation.

The application of support vector machine in classifying potential archers using bio-mechanical indicators

This study classifies potential archers from a set of bio-mechanical indicators trained via different Support Vector Machine (SVM) models. 50 youth archers drawn from a number of archery programmes completed a one end archery shooting score test. Bio-mechanical evaluation of postural sway, bow movement, muscles activation of flexor and extensor as well as static balance were recorded. k-means clustering technique was used to cluster the archers based on the indicators tested. Fine, medium and coarse radial basis function kernel-based SVM models were trained based on the measured indicators. The five-fold cross-validation technique was utilised in the present investigation. It was shown from the present study, that the employment of SVM is able to assist coaches in identifying potential athletes in the sport of archery.

Mechanics of Soccer Heading and Protective Headgear

This short book provides a concise study of the mechanics of head impact in a soccer heading manoeuvre. It describes the development and validation of finite element models of soccer ball and human head, as well as the simulation of brain dynamics after ball-to-head impact. In addition, it also presents a computational study of the efficacy of wearing protective headgear in mitigating the risk of concussion due to heading in soccer.

The Identification and Control of a Finger Exoskeleton for Grasping Rehabilitation

This paper evaluates the efficacy of different classical control architectures in performing grasping motion. The exoskeleton system was obtained via system identification method in which the input and output data was measured by means of current sensor (ACS712) and encoder attached to a DC geared motor (SPG30e-270k). The data obtained is split with a ratio of 70:30 for estimation and validation, respectively. The transfer function of the system is evaluated by varying the number of poles and zeros that are able to fit well with validation data. The performance of the classical P, PI, PD and PID control techniques were then evaluated in its ability to track the desired trajectory. It was demonstrated from the study that the PID controller provides the least steady state error as well as a reasonably fast settling time.

Human Head Finite Element Model

This chapter discusses the development of a simplified human head finite element model. It comprises of four components: the skull, facial bones, cerebrospinal fluid (CSF) and the brain. The material properties of each component are adopted from various literature.

Soccer Ball Finite Element Model

This chapter describes the development of the soccer ball FE model and its validation. The geometry of the ball and the material properties of each layer of the ball model are presented. In addition, the pressurization of the ball is also described. The model was validated against a more advanced soccer ball model.

Concussion in Soccer

This chapter covers the review of literature that motivates this work. This includes a brief overview of sports-related head injuries, particularly in soccer, and the efficacy of protective headgears in mitigating the impact due to soccer heading.