Investigation of Human Balance Ability and Development of a New Sensory Oriented Posture Control Model Based on Joint Stiffness Characteristics

芝浦工業大学201

Effect of Sensory Manipulations on Human Joint Stiffness Strategy and Its Adaptation for Human Dynamic Stability

Sensory input plays an important role to human posture control system to initiate strategy in order to counterpart any unbalance condition and thus, prevent fall. In previous study, joint stiffness was observed able to describe certain issues regarding to movement performance. But, correlation between balance ability and joint stiffness is still remains unknown. In this study, joint stiffening strategy at ankle and hip were observed under different sensory manipulations and its correlation with conventional clinical test (Functional Reach Test) for balance ability was investigated. In order to create unstable condition, two different surface perturbations (tilt up-tilt (TT) down and forward-backward (FB)) at four different frequencies (0.2, 0.4, 0.6 and 0.8 Hz) were introduced. Furthermore, four different sensory manipulation conditions (include vision and vestibular system) were applied to the subject and they were asked to maintain their position as possible. The results suggested that joint stiffness were high during difficult balance situation. Less balance people generated high average joint stiffness compared to balance people. Besides, adaptation of posture control system under repetitive external perturbation also suggested less during sensory limited condition. Overall, analysis of joint stiffening response possible to predict unbalance situation faced by human

Recognition of Badminton Action Using Convolutional Neural Network

Deep learning approach has becoming a research interest in action recognition application due to its ability to surpass the performance of conventional machine learning approaches. Convolutional Neural Network (CNN) is among the widely used architecture in most action recognition works. There are various models exist in CNN but no research has been done to analyse which model has the best performance in recognizing actions for badminton sport. Hence, in this paper we are comparing the performance of four different pre-trained models of deep CNN in classifying the badminton match images to recognize the different actions done by the athlete. Four models used for comparison are AlexNet, GoogleNet, VggNet-16 and VggNet-19. The images used in this experimental work are categorized into two classes: hit and non-hit action. Firstly, each image frame was extracted from Yonex All England Man Single Match 2017 broadcast video. Then, the image frames were fed as the input to each classifier model for classification. Finally, the performance of each classifier model was evaluated by plotting its performance accuracy in form of confusion matrix. The result shows that the GoogleNet model has the highest classification accuracy which is 87.5% compared to other models. In a conclusion, the pre-trained GoogleNet model is capable to be used in recognizing actions in badminton match which might be useful in badminton sport performance technology

Effects of Baby Carrier on Wearer’s Posture Stability / Aizreena Azaman...[et al.]

Design of baby carrier mostly focused on baby’s needs. But less consideration have been given to wearer. The objective of this study is to investigate the effect of baby carrier on the wearer’s posture stability and displacement. It was hypothesized that baby carrier would reduce loading effect caused by baby’s weight on the wearer’s body. Fifteen healthy young female volunteered to participate in this study. Three dimensional motion data and force distribution were collected using 3D Investigator system and force platform respectively. Subjects underwent three conditions of standing which are standing on the force plate without load (Control), standing on the force plate with load only (L) and standing on the force plate with load and wearing a baby carrier (LBC). In this study, dummy baby was used to create load effect mimicking real baby’s weight. For every condition, active markers will be placed at the subject’s joint and the subject is asked to standing quietly on the force plate. Then, effect of different position of baby carrier also will be analysed including front position, back position, and side position. In this investigation wrapping type of baby carrier or Mei Tai is used. Collected data were used to measure Centre of Pressure (COP) and joint displacement. The results shows that by using baby carrier there are significance change in shoulder and pelvic joint displacement. Baby carrier also reduced the COP sway compared to other condition, but no significance changes recorded. Even though changes in posture displacement and the COP sway were relatively small, further study is still warranted to improve function and comfort design of baby carrier

Electromyography (EMG) for assessment in low back pain; erector spinae muscle

The purpose of electromyography (EMG) study is to identify which position of surface EMG sensor attached to erector spinae muscle related with lower back pain by squat and stoop lifting technique. This is to avoid lower back pain (LBP) occur during Manual Materials Handling (MMH). There are only one types of upper extremity muscle were chosen to be monitored in this study which is erector spinae (ES) muscle with different electrodes placement on the surface electromyography (sEMG) sensor. However, each of the lifting styles come out with the different reading of root mean square (RMS) frequency for each muscle chosen. In this study, the two subjects consist of two females with normal body mass index (BMI) range from 18.5 to 24.9 with same physical measurement, was selected in order to perform both styles of lifting which are squatting and stooping. For every session the subject will undertake 15 repetitions with 15 minutes rest in between for each movement. In furtherance of to get the analysis muscle activity, proEMG software is used. The results of study for subject female 1 showed that the squat technique had higher levels of muscle activation compared to stoop technique on left erector spinae (LES) muscle. However, the LES muscle activation for subject 2 is greater at stoop activity. On the contrary, squat technique had lower fatigue analysis compared to stoop technique for both subjects on LES muscle. Conclusion, squat technique is better than stoop technique but stoop lift is more natural and spontaneously used for MMH

Biomechanical evaluation of pin placement of external fixator in treating tranverse tibia fracture: analysis on first and second cortex of cortical bone

Biomechanical perspective of external fixator is one of the greatest factor to consider in successfully treating bone fracture. This is due to the fact that mechanical behavior of the structure can be analyzed and optimized in order to avoid mechanical failure, increase bone fracture healing rate and prevent pre-term screw loosening. There are three significant factors that affect the stability of external fixator which are the placement of pin at the bone, configuration and components of external fixator. These factors lead to one question: what is the optimum pin placement in which exerts optimum stability? To date, literature on above mentioned factors is limited. Therefore, we conducted a study to evaluate the uniplanar-unilateral external fixator for two different pin placement techniques in treating transverse tibia fracture via finite element method. The study was started off with the development of transverse tibia fracture using Mimics software. Computed tomography (CT) data image was utilized to develop three dimensional tibia bone followed by crafting fracture on the bone. Meanwhile, the external fixator was developed using SolidWork software. Both tibia bone and external fixator were meshed in 3-matic software with triangular mesh element. Simulation of this configuration was took place in a finite element software, Marc.Mentat software. A load of 400 N was applied to the proximal tibia bone in order to simulate stance phase of a gait cycle. From the findings, the pin placement at the second cortex of bone provided optimum stability in terms of stress distribution and displacement, which should be considered for better treatment for transverse tibia fracture. On the other hand, the pin placement at first cortex should be avoided to prevent many complications

Electromagnetic flux modelling of AC field over planar microarray dot electrodes used in rapid dielectrophoretic lab-on-chip device / Aizreena Azaman

This research presents a simulation procedure to determine electromagnetic flux produced by planar microarray electrode used in dielectrophoretic lab-on-device. Recently, dielectrophoretic lab-on-device was a useful technique that offers a simple microarray electrode for sorting and manipulating particles. Here, the finite element method (FEM) (COMSOL package) has been employed to model and simulate this model. The electrode model was developed by using three different conductive materials such as copper, gold and indium tin oxide (ITO). Based on Clausius-Massotti factor, frequency, conductivity and permittivity of particles and conductive medium play an importance role in the production of dielectrophoresis force. Thus, in order to simulate and determine the production of electromagnetic field, this microarray electrode was applied with different frequencies values which are 50Hz, 100Hz, 1 KHz, 50 KHz and 500 KHz; and different conductive medium such as distilled water, air at 1 atmosphere (atm) and yeast solution. Statistical analysis made based on the simulation result has shown that copper produced a wide range of electromagnetic flux density compared with other 2 materials. Besides, different conductive medium applied did not bring any changes towards the electromagnetic flux density produced

Ankle joint stiffness and damping pattern under different frequency of translation perturbation

The change of e ffective stiffness and damping characteristic of ankle joint are able to indicate degeneration of balance ability due to ageing effect. This paper will discuss the ankle joint stiffness and damping pattern along repeat ed translation perturbation. Six young healthy subjects were exposed to five tr ials of five different frequencies of perturbation (quiet standing, 0.2 Hz, 0.4 Hz, 0.6 Hz and 0.8 Hz). The result showed that the me an of effective stif fness was reduced with the increase of frequency applied ; meanwhile the mean of damping value increased wit h increasing frequency . Additionally , a cubic polynomial curve (u - shape) was estimated to represent stiffness pattern when using curve fitting method with correlation R 2 >0.5 . These estimation s also suggested that ankle joint does not oscillate like sprin g - damper system which is based on inverted pendulum model ; however , it applied a different strategy to maintain balance, in particular during initiation, middle and termination of perturbation. These also indicate the influence of sensory processing and ad aptation to maintain balance under a long period of disturbance . On the other hand, damping pattern seems to be similar over different frequenc ies and under repeat ed perturbation . Besides, the change of stiffness patter n at higher frequency o f perturbati on (0.8 Hz) recommends the change in posture strategy from ankle to hip strategy . The se findings indicated that stiffness and damping are able to describe adaptation of human posture strategy to keep balance and motor learnin g under repeat ed perturbation