UNRESTRAINED MEASUREMENT OF ARM MOTION BASED ON A WEARABLE WIRELESS SENSOR NETWORK

Techniques that could precisely monitor human motion are useful in applications such as rehabilitation, virtual reality, sports science, and surveillance. Most of the existing systems require wiring that restrains the natural movement. To overcome this limitation, a wearable wireless sensor network using accelerometers has been developed in this paper to determine the arm motion in the sagittal plane. The system provides unrestrained movements and improves its usability. The lightweight and compact size of the developed sensor node makes its attachment to the limb easy. Experimental results have shown that the system has good accuracy and response rate when compared with a goniometer

Preparation of NiO catalyst on FeCrAI substrate using various techniques at higher oxidation process

The cheap nickel oxide (NiO) is a potential catalyst candidate to replace the expensive available platinum group metals (PGM). However, the current methods to adhere the NiO powder on the metallic substrates are complicated. Therefore, this work explored the development of nickel oxide using nickel (Ni) on FeCrAl substrate through the combination of nickel electroplating and oxidation process for catalytic converter application. The approach was started with assessment of various nickel electroplating process based on the weight gain during oxidation. Then, the next experiment used the best process in which the pre-treatment using the solution of SiC and/or Al2O3 in methanol. The specimens then were carried out to short term oxidation process using thermo gravimetric analysis (TGA) at 1000 o C. Meanwhile, the long term oxidation process was conducted using an automatic furnace at 900, 1000 and 1100 o C. The atomic force microscopy (AFM) was used for surface analysis in nanometer range scale. Meanwhile, roughness test was used for roughness measurement analysis in micrometer range scale. The scanning electron microscope (SEM) attached with energy dispersive X-ray (EDX) were used for surface and cross section morphology analysis. The specimen of FeCrAl treated using ultrasonic prior to nickel electroplating showed the lowest weight gain during oxidation. The surface area of specimens increased after ultrasonic treatment. The electroplating process improved the high temperature oxidation resistance. In short term oxidation process indicated that the ultrasonic with SiC provided the lower parabolic rate constant (kp) and the Al2O3 and NiO layers were also occurred. The Ni layer was totally disappeared and converted to NiO layer on FeCrAl surface after long term oxidation process. From this work, the ultrasonic treatment prior to nickel electroplating was the best method to adhere NiO on FeCrAl substrate

Recognition of elementary arm movements using orientation of a tri-axial accelerometer located near the wrist

In this paper we present a method for recognising three fundamental movements of the human arm (reach and retrieve, lift cup to mouth, rotation of the arm) by determining the orientation of a tri-axial accelerometer located near the wrist. Our objective is to detect the occurrence of such movements performed with the impaired arm of a stroke patient during normal daily activities as a means to assess their rehabilitation. The method relies on accurately mapping transitions of predefined, standard orientations of the accelerometer to corresponding elementary arm movements. To evaluate the technique, kinematic data was collected from four healthy subjects and four stroke patients as they performed a number of activities involved in a representative activity of daily living, 'making-a-cup-of-tea'. Our experimental results show that the proposed method can independently recognise all three of the elementary upper limb movements investigated with accuracies in the range 91–99% for healthy subjects and 70–85% for stroke patients

Unrestrained measurement of arm motion based on a wearable wireless sensor network

Measurement of human body motion has a myriad of applications ranging from gaming, rehabilitation, animation, virtual reality, sports science and surveillance. Existing methods of motion tracking include visual, mechanical, magnetic and inertial tracking. Visual methods require line of sight and suffer from the notorious occlusion problem. For the existing mechanical or inertial tracking methods, they have cumbersome wiring which hinder the natural movements. In this thesis, a wearable wireless sensor network using inertial/ magnetic sensors is developed to overcome the limitations of these existing methods. Using tri-axial accelerometer as the sole sensor will lead to singularity when the heading axis is vertical, restricting measurement of orientation to half a vertical plane. A new factorized quaternion approach is proposed in this research to overcome this deficiency with consideration of anatomical and sensor constraints. Different from the conventional approach based on single angle-axis quaternion, the proposed approach factorizes the quaternion into two principal axis quaternions corresponding to two equivalent arm motions. This allows for the implementation of anatomical arm constraints that match the range of arm motion and reduces the ambiguity in solutions. In addition, the singularities arising from the use of tri-axial accelerometers can be detected and resolved for a transient state. A novel algorithm based on elevation and heading angles is also proposed to determine the orientation of a sensor node equipped with tri-axial accelerometer, gyroscope and magnetometer. Compared to Euler angles, the fixed elevation and heading angles are independent on the temporal order of rotations. In addition, the fixed elevation and heading angles are observable and thus more intuitively visualized. External acceleration due to the rotation of the human arm segment is estimated using the gyroscope and compensated in the accelerometer output. As the magnetometer is easily affected by magnetic disturbances caused by electrical appliances and ferrous materials, it is decoupled from the accelerometer and used solely for the determination of heading. A new singularity avoidance method is also proposed to resolve the singularity problem that may arise, thereby allowing for measurement through all possible orientations. Experiments have been performed to evaluate the proposed wearable wireless sensor network in terms of accuracy, latency and power consumption. Experimental results show that the proposed factorized quaternion approach is able to resolve transient singularities and ambiguity arising from the use of triaxial accelerometer. Performance of the novel elevation and heading algorithm is also comparable to an indirect Kalman Filter at a reduced computational cost. The implementation of a singularity avoidance strategy makes the algorithm suitable for implementation in a fixed-point processor. Magnetic disturbances affect only the accuracy of the heading angle and not the elevation angles.DOCTOR OF PHILOSOPHY (EEE

SWORD: um dispositivo vibratório vestível para uma rabilitação mais eficiente em doentes com AVC

Doutoramento em Engenharia ElectrotécnicaAnualmente ocorrem cerca de 16 milhões AVCs em todo o mundo. Cerca de metade dos sobreviventes irá apresentar défice motor que necessitará de reabilitação na janela dos 3 aos 6 meses depois do AVC. Nos países desenvolvidos, é estimado que os custos com AVCs representem cerca de 0.27% do Produto Interno Bruto de cada País. Esta situação implica um enorme peso social e financeiro. Paradoxalmente a esta situação, é aceite na comunidade médica a necessidade de serviços de reabilitação motora mais intensivos e centrados no doente. Na revisão do estado da arte, demonstra-se o arquétipo que relaciona metodologias terapêuticas mais intensivas com uma mais proficiente reabilitação motora do doente. Revelam-se também as falhas nas soluções tecnológicas existentes que apresentam uma elevada complexidade e custo associado de aquisição e manutenção. Desta forma, a pergunta que suporta o trabalho de doutoramento seguido inquire a possibilidade de criar um novo dispositivo de simples utilização e de baixo custo, capaz de apoiar uma recuperação motora mais eficiente de um doente após AVC, aliando intensidade com determinação da correcção dos movimentos realizados relativamente aos prescritos. Propondo o uso do estímulo vibratório como uma ferramenta proprioceptiva de intervenção terapêutica a usar no novo dispositivo, demonstra-se a tolerabilidade a este tipo de estímulos através do teste duma primeira versão do sistema apenas com a componente de estimulação num primeiro grupo de 5 doentes. Esta fase validará o subsequente desenvolvimento do sistema SWORD. Projectando o sistema SWORD como uma ferramenta complementar que integra as componentes de avaliação motora e intervenção proprioceptiva por estimulação, é descrito o desenvolvimento da componente de quantificação de movimento que o integra. São apresentadas as diversas soluções estudadas e o algoritmo que representa a implementação final baseada na fusão sensorial das medidas provenientes de três sensores: acelerómetro, giroscópio e magnetómetro. O teste ao sistema SWORD, quando comparado com o método de reabilitação tradicional, mostrou um ganho considerável de intensidade e qualidade na execução motora para 4 dos 5 doentes testados num segundo grupo experimental. É mostrada a versatilidade do sistema SWORD através do desenvolvimento do módulo de Tele-Reabilitação que complementa a componente de quantificação de movimento com uma interface gráfica de feedback e uma ferramenta de análise remota da evolução motora do doente. Finalmente, a partir da componente de quantificação de movimento, foi ainda desenvolvida uma versão para avaliação motora automatizada, implementada a partir da escala WMFT, que visa retirar o factor subjectivo da avaliação humana presente nas escalas de avaliação motora usadas em Neurologia. Esta versão do sistema foi testada num terceiro grupo experimental de cinco doentes.About 16 million first ever-strokes occur worldwide every year. Half of stroke survivors are left with some degree of physical impairment that needs rehabilitation in the 3 to 6 month after-stroke time window. This situation implies a high economic and social burden. In developed countries, stroke cost is estimated to represent an average of 0.27% of each country’s gross domestic product. Paradoxically, it is accepted in the medical community the need for more intensive and patient-centered rehabilitation services. In the state of art review, it is demonstrated the archetype that relates the intensity on rehabilitation with a proficient motor recovery of the patient. Additionally, it is shown that the major pitfalls in current technological solutions in the field of motor rehabilitation are due to their intrinsic complexity and associated cost. Given this state of the art, the research question that supports this thesis, inquiries the possibility of creating a novel low-cost device targeted at the motor rehabilitation of stroke patients, capable of providing a more efficient treatment through enabling higher intensity and automated determination of the correctness of the movements performed by the recovering patient. The validity of the vibratory stimulus is presented from an historic and neurophysiologic point of view. Furthermore, a state of art review of motion capture systems is presented. Intending the use of the vibratory stimulus as a proprioceptive therapeutic tool to be integrated in the new device, it is demonstrated the tolerability of the stimulus from the experimental test of a first version of the device, incorporating the stimulation component, in a first group of five patients. Projecting the SWORD device as a tool that combines both features of motor function evaluation with proprioceptive intervention through vibratory stimulation, it is described the development of the motion capture component. Several solutions were studied and the final algorithm, based on the sensory fusion of the measures from three sensors (accelerometer, gyroscope and magnetometer), is described in detail. The experimental test of the SWORD system on a second group of patients showed that, when compared with a typical treatment, it is capable of providing a more intensive intervention and with a higher quality in 4 out of 5 patients. To demonstrate the versatility of the SWORD system, it was developed the tele-rehabilitation module that complements the motion capture component with a graphical feedback interface and a remote tool for the clinician to evaluate the performance of the patient through out the time he uses the system in his home or any other remote environment. Finally, from the motion capture component, a motor function evaluation version of the system was deployed. Implemented from the WMFT scale, it aims to eliminate the human subjectivity present in the traditional evaluation scales used in the neurology medical area. This system was evaluated on a third group of five patients