Implementación de métodos computacionales para estimar las amplitudes angulares de los miembros inferiores durante el squat

In biomechanics, motion capture systems based on video and markers are the most widely used method to estimate kinematic parameters. However, from a technical standpoint, experimental errors in data capture are often related to the masking of markers during motion capture. This phenomenon generates data loss that can affect the analysis of the results. The lack of data is solved by increasing the number of cameras or using additional devices such as inertial sensors. However, those additions increase the experimental cost of this method. Nowadays, new computational methods can be used to solve such problems less expensively. This study implemented two computational methods based on Artificial Neural Networks (ANNs) and Support Vector Regression (SVR) to estimate the amplitude of limb angles during the execution of a movement on a single axis (i.e., the z-axis). The characteristics of the squats were used to train and validate the models. The results obtained include RMSE values lower than 14 (minimum RMSE of 5.35) and CC values close to 0.98. The estimated values are very close to the experimental amplitude angles, and the statistical analyses showed no significant differences between the distributions and means of the estimated amplitude values and their actual counterparts (p-value>0.05). The results show that these methods could help biomechanics researchers perform accurate analyses, decrease the number of cameras needed, reduce uncertainty, and avoid data loss problems.En biomecánica, los sistemas de captura de movimiento basados en video y en marcadores son el método más utilizado para la estimación de parámetros cinemáticos. A nivel técnico, los errores experimentales en la captura de datos suelen estar relacionados con el ocultamiento de los marcadores durante la captura del movimiento. Este fenómeno genera una pérdida de datos que puede afectar el análisis de los resultados. La falta de datos se resuelve aumentando el número de cámaras o utilizando dispositivos adicionales como sensores inerciales. Estas adiciones incrementan el costo experimental de este método. Actualmente, para resolver este tipo de problemas de forma menos costosa, se podrían utilizar nuevos métodos computacionales. Este estudio tiene como objetivo implementar dos métodos computacionales basados en red neuronal artificial (RNA) y regresión de vectores de soporte (RVS) para estimar la amplitud del ángulo de las extremidades durante la ejecución de un movimiento a partir de un solo eje (eje Z). Para entrenar y validar los modelos, se utilizaron características del ejercicio de squat. Los resultados obtenidos incluyeron valores de raíces de error cuadrático medio (RMSE) inferiores a 14 (RMSE mínimo de 5.35) y valores de CC cercanos a 0.98. Los valores estimados son muy cercanos a los ángulos de amplitud experimentales, los análisis estadísticos muestran que no hay diferencias significativas entre las distribuciones y las medias de los valores de amplitud estimados y los valores reales (valor p>0.05). Los resultados demuestran que estos métodos podrían ayudar a los investigadores en biomecánica a realizar análisis precisos, reduciendo el número de cámaras necesarias, reduciendo la incertidumbre y evitando problemas por perdida de datos

Understanding the Shared Experiences of Runners and Spectators in Long-Distance Running Events

attract not just runners but an exponentially increasing number of spectators. Due to the long duration and broad geographic spread of such events, interactions between them are limited to brief moments when runners (R) pass by their supporting spectators (S). Current technology is limited in its potential for supporting interactions and mainly measures and displays basic running information to spectators who passively consume it. In this paper, we conducted qualitative studies for an in-depth understanding of the R&S’ shared experience during LDRE and how technology can enrich this experience. We propose a two-layer DyPECS framework, highlighting the rich dynamics of the R&S multi-faceted running journey and of their micro-encounters. DyPECS is enriched by the findings from our in depth qualitative studies. We finally present design implications for the multifacet co-experience of R&S during LDRE

Efeito da sobrecarga muscular aguda e crónica no senso de posição articular do joelho

Introdução: O Senso de Posição Articular (SPA) dita a capacidade de compreender e reproduzir um ângulo articular, e é assegurado por mecanorrecetores cutâneos, articulares e musculares. Apesar de existir evidência de que a fadiga muscular aumenta o limiar de descarga do fuso neuromuscular, o efeito da fadiga no SPA do joelho ainda não é consensual. O objetivo desta investigação foi determinar o efeito da sobrecarga muscular aguda e crónica na acuidade propriocetiva do joelho, especificamente no SPA. Metodologia: Participaram no estudo 60 indivíduos, 29 jogadores de futebol (JF) e 31 não-praticantes de desporto (NP). O SPA do joelho do membro dominante (MD) e não-dominante (MND) foi avaliado em cadeia cinética aberta e através de reposicionamento ativo, com centrais inerciais e uma câmara de vídeo. Os efeitos agudos da fadiga sobre o SPA do joelho foram analisados em ambos os grupos antes e imediatamente após uma tarefa repetida de levantar/sentar, para as amplitudes de 20º e 45º de flexão. A sobrecarga muscular crónica foi estimada nos JF analisando a variação do SPA do joelho ao longo da época, para as amplitudes de 20º e 45º (teste de extensão), e 45º e 100º (teste de flexão). Principais Resultados: O protocolo de fadiga afetou apenas o SPA do joelho dos NP no reposicionamento dos 45º do MD (p=0.034). A acuidade propriocetiva de JF é superior à de NP (p0.005). Pelo contrário, em NP, na avaliação em repouso o MD apresentou uma acuidade significativamente superior, tanto na amplitude de 20º (p=0.046) como na de 45º (p=0.036), mas inferior após o protocolo de fadiga aos 45º (p=0.050). Nos NP não se registaram diferenças no SPA do joelho inerentes ao género. No entanto, em JF, após a fadiga, o SPA das JF femininas foi significativamente inferior ao dos JF masculinos, tanto no reposicionamento dos 20º (p=0.041) como dos 45º (p=0.046) do MD. O SPA do joelho de JF não variou ao longo da época (p>0.005). No teste de extensão, uma acuidade propriocetiva significativamente inferior foi observada na amplitude de 45º, apenas no MND (p=0.012). No teste de flexão, a acuidade propriocetiva foi significativamente inferior aos 45º em relação aos 100º, tanto no MD (p=0.004) como no MND (p=0.001). Conclusões: A fadiga não tem efeitos agudos no SPA do joelho de JF, mas diminui o de NP. A acuidade propriocetiva de JF é superior à de NP. Os JF e NP falham as amplitudes-alvo por sobrestimação e subestimação, respetivamente. Em JF, a dominância não influencia a acuidade propriocetiva do joelho, mas em NP, o membro dominante apresenta uma acuidade superior em repouso, mas inferior em fadiga. Em repouso, não existem diferenças no SPA do joelho inerentes ao género, no entanto, quando se encontra em fadiga, o membro dominante de JF femininas apresenta uma acuidade inferior à de JF masculinos. A sobrecarga muscular crónica não faz variar o SPA do joelho de JF ao longo de uma época. A acuidade propriocetiva é inferior nas amplitudes intermédias da amplitude de movimento do joelho.Introduction: Joint Position Sense (JPS) dictates the ability to understand and reproduce a joint angle, and it is provided by skin, muscle and joint mechanoreceptors. Although there is evidence that muscle fatigue increases the discharge threshold of the neuromuscular spindle, the effect of muscle fatigue on the knee JPS is still not consensual. The aim of this investigation was to determine the effect of acute and chronic muscle overload on knee proprioceptive acuity, and specifically in the JPS. Methodology: The sample consisted of 60 subjects, 29 soccer players (SP) and 31 individuals who didn’t practice any sports (NP). Knee JPS of the dominant (DL) and non-dominant limb (NDL) was evaluated through an open kinetic chain and active repositioning method, using a central inertial system and a video camera. Acute effects of fatigue on knee JPS were analysed in both groups before and immediately after a repetitive sit to stand task, to the ranges of 20º and 45º of knee flexion. Chronic muscle overload was estimated in the SP by analysing their knee JPS variation during one season, for the ranges of 20º and 45º (knee extension test), and 45º and 100º (knee flexion test). Main Results: Fatigue protocol only affected the knee JPS of the NP in the 45º repositioning of the DL (p=0.034). Proprioceptive acuity is higher in the SP than in the NP (p0.005). In the knee extension test, a significantly lower proprioceptive acuity was observed in the 45º range, only in the NDL (p=0.012). In the knee flexion test, proprioceptive acuity was significantly lower at 45º than at 100º, both in the DL (p=0.004) as in the NDL (p=0.001). Conclusions: Fatigue doesn’t have acute effects on knee JPS in SP but decreases JPS in NP. Proprioceptive acuity is higher in SP than in NP. SP and NP fail the target ranges by over and underestimation, respectively. In SP, dominance doesn’t influence knee proprioceptive acuity, but in NP, the DL shows a higher acuity at rest, but lower in a fatigue state. At rest, there are no differences in knee JPS related to gender, although when in a fatigue state, the DL of the female players exhibits a lower acuity when compared to the male players. Chronic muscle overload doesn’t cause a variation of the knee JPS in SP throughout one season. Proprioceptive acuity is lower in the intermediate ranges of the knee range of motion

Human Activity Recognition and Control of Wearable Robots

abstract: Wearable robotics has gained huge popularity in recent years due to its wide applications in rehabilitation, military, and industrial fields. The weakness of the skeletal muscles in the aging population and neurological injuries such as stroke and spinal cord injuries seriously limit the abilities of these individuals to perform daily activities. Therefore, there is an increasing attention in the development of wearable robots to assist the elderly and patients with disabilities for motion assistance and rehabilitation. In military and industrial sectors, wearable robots can increase the productivity of workers and soldiers. It is important for the wearable robots to maintain smooth interaction with the user while evolving in complex environments with minimum effort from the user. Therefore, the recognition of the user's activities such as walking or jogging in real time becomes essential to provide appropriate assistance based on the activity. This dissertation proposes two real-time human activity recognition algorithms intelligent fuzzy inference (IFI) algorithm and Amplitude omega ($A \omega$) algorithm to identify the human activities, i.e., stationary and locomotion activities. The IFI algorithm uses knee angle and ground contact forces (GCFs) measurements from four inertial measurement units (IMUs) and a pair of smart shoes. Whereas, the $A \omega$ algorithm is based on thigh angle measurements from a single IMU. This dissertation also attempts to address the problem of online tuning of virtual impedance for an assistive robot based on real-time gait and activity measurement data to personalize the assistance for different users. An automatic impedance tuning (AIT) approach is presented for a knee assistive device (KAD) in which the IFI algorithm is used for real-time activity measurements. This dissertation also proposes an adaptive oscillator method known as amplitude omega adaptive oscillator ($A\omega AO$) method for HeSA (hip exoskeleton for superior augmentation) to provide bilateral hip assistance during human locomotion activities. The $A \omega$ algorithm is integrated into the adaptive oscillator method to make the approach robust for different locomotion activities. Experiments are performed on healthy subjects to validate the efficacy of the human activities recognition algorithms and control strategies proposed in this dissertation. Both the activity recognition algorithms exhibited higher classification accuracy with less update time. The results of AIT demonstrated that the KAD assistive torque was smoother and EMG signal of Vastus Medialis is reduced, compared to constant impedance and finite state machine approaches. The $A\omega AO$ method showed real-time learning of the locomotion activities signals for three healthy subjects while wearing HeSA. To understand the influence of the assistive devices on the inherent dynamic gait stability of the human, stability analysis is performed. For this, the stability metrics derived from dynamical systems theory are used to evaluate unilateral knee assistance applied to the healthy participants.Dissertation/ThesisDoctoral Dissertation Aerospace Engineering 201

Efeito da sobrecarga muscular aguda e crónica no senso de posição articular do joelho

Introdução: O Senso de Posição Articular (SPA) dita a capacidade de compreender e reproduzir um ângulo articular, e é assegurado por mecanorrecetores cutâneos, articulares e musculares. Apesar de existir evidência de que a fadiga muscular aumenta o limiar de descarga do fuso neuromuscular, o efeito da fadiga no SPA do joelho ainda não é consensual. O objetivo desta investigação foi determinar o efeito da sobrecarga muscular aguda e crónica na acuidade propriocetiva do joelho, especificamente no SPA. Metodologia: Participaram no estudo 60 indivíduos, 29 jogadores de futebol (JF) e 31 não-praticantes de desporto (NP). O SPA do joelho do membro dominante (MD) e não-dominante (MND) foi avaliado em cadeia cinética aberta e através de reposicionamento ativo, com centrais inerciais e uma câmara de vídeo. Os efeitos agudos da fadiga sobre o SPA do joelho foram analisados em ambos os grupos antes e imediatamente após uma tarefa repetida de levantar/sentar, para as amplitudes de 20º e 45º de flexão. A sobrecarga muscular crónica foi estimada nos JF analisando a variação do SPA do joelho ao longo da época, para as amplitudes de 20º e 45º (teste de extensão), e 45º e 100º (teste de flexão). Principais Resultados: O protocolo de fadiga afetou apenas o SPA do joelho dos NP no reposicionamento dos 45º do MD (p=0.034). A acuidade propriocetiva de JF é superior à de NP (p0.005). Pelo contrário, em NP, na avaliação em repouso o MD apresentou uma acuidade significativamente superior, tanto na amplitude de 20º (p=0.046) como na de 45º (p=0.036), mas inferior após o protocolo de fadiga aos 45º (p=0.050). Nos NP não se registaram diferenças no SPA do joelho inerentes ao género. No entanto, em JF, após a fadiga, o SPA das JF femininas foi significativamente inferior ao dos JF masculinos, tanto no reposicionamento dos 20º (p=0.041) como dos 45º (p=0.046) do MD. O SPA do joelho de JF não variou ao longo da época (p>0.005). No teste de extensão, uma acuidade propriocetiva significativamente inferior foi observada na amplitude de 45º, apenas no MND (p=0.012). No teste de flexão, a acuidade propriocetiva foi significativamente inferior aos 45º em relação aos 100º, tanto no MD (p=0.004) como no MND (p=0.001). Conclusões: A fadiga não tem efeitos agudos no SPA do joelho de JF, mas diminui o de NP. A acuidade propriocetiva de JF é superior à de NP. Os JF e NP falham as amplitudes-alvo por sobrestimação e subestimação, respetivamente. Em JF, a dominância não influencia a acuidade propriocetiva do joelho, mas em NP, o membro dominante apresenta uma acuidade superior em repouso, mas inferior em fadiga. Em repouso, não existem diferenças no SPA do joelho inerentes ao género, no entanto, quando se encontra em fadiga, o membro dominante de JF femininas apresenta uma acuidade inferior à de JF masculinos. A sobrecarga muscular crónica não faz variar o SPA do joelho de JF ao longo de uma época. A acuidade propriocetiva é inferior nas amplitudes intermédias da amplitude de movimento do joelho.Introduction: Joint Position Sense (JPS) dictates the ability to understand and reproduce a joint angle, and it is provided by skin, muscle and joint mechanoreceptors. Although there is evidence that muscle fatigue increases the discharge threshold of the neuromuscular spindle, the effect of muscle fatigue on the knee JPS is still not consensual. The aim of this investigation was to determine the effect of acute and chronic muscle overload on knee proprioceptive acuity, and specifically in the JPS. Methodology: The sample consisted of 60 subjects, 29 soccer players (SP) and 31 individuals who didn’t practice any sports (NP). Knee JPS of the dominant (DL) and non-dominant limb (NDL) was evaluated through an open kinetic chain and active repositioning method, using a central inertial system and a video camera. Acute effects of fatigue on knee JPS were analysed in both groups before and immediately after a repetitive sit to stand task, to the ranges of 20º and 45º of knee flexion. Chronic muscle overload was estimated in the SP by analysing their knee JPS variation during one season, for the ranges of 20º and 45º (knee extension test), and 45º and 100º (knee flexion test). Main Results: Fatigue protocol only affected the knee JPS of the NP in the 45º repositioning of the DL (p=0.034). Proprioceptive acuity is higher in the SP than in the NP (p0.005). In the knee extension test, a significantly lower proprioceptive acuity was observed in the 45º range, only in the NDL (p=0.012). In the knee flexion test, proprioceptive acuity was significantly lower at 45º than at 100º, both in the DL (p=0.004) as in the NDL (p=0.001). Conclusions: Fatigue doesn’t have acute effects on knee JPS in SP but decreases JPS in NP. Proprioceptive acuity is higher in SP than in NP. SP and NP fail the target ranges by over and underestimation, respectively. In SP, dominance doesn’t influence knee proprioceptive acuity, but in NP, the DL shows a higher acuity at rest, but lower in a fatigue state. At rest, there are no differences in knee JPS related to gender, although when in a fatigue state, the DL of the female players exhibits a lower acuity when compared to the male players. Chronic muscle overload doesn’t cause a variation of the knee JPS in SP throughout one season. Proprioceptive acuity is lower in the intermediate ranges of the knee range of motion

Drift Reduction for Inertial Sensor Based Orientation and Position Estimation in the Presence of High Dynamic Variability During Competitive Skiing and Daily-Life Walking

Nowadays inertial sensors are extensively used for gait analysis. They can be used to perform temporal event detection (i.e. step detection) and to estimate the orientation of the feet and other body segments to determine walking speed and distance. Usually, orientation is estimated from integration of the measured angular velocity. Prior to integration of measured acceleration to obtain speed, the gravity component has to be estimated and removed. During each integration small measurement errors accumulate and result in so-called drift. Since the first uses of inertial sensors for gait analysis methods have been presented to model, estimate and remove the drift. The proposed methods worked well for relatively slow movements and movements taking place in the sagittal plane. Many methods also relied on periodically occurring static phases such as the stance phase during walking to correct the drift. Inertial sensors could also be used to track higher dynamic movements, for example in sports. Potential applications focus on two aspects: performance analysis and injury prevention. To better explain and predict performance, in-field measurements to assess the coordination, kinematics, and dynamics are key. While traditional movement analysis (e.g. video analysis) can answer most of the questions related to both performance and injury, they are cumbersome and complex to use in-field. Inertial sensors, however, are perfectly suited since they allow to measure the movement in any environment and are not restricted to certain capture volumes. Nevertheless, most sports have very high movement dynamics (e.g. fast direction changes, high speeds) and are therefore challenging for computing reliable estimates of orientation, speed and position. The inertial measurements are compromised by noise and movements oftentimes don't provide static or slow phases used in gait analysis for drift correction. Therefore, the present thesis aimed to propose and validate new methods to model, estimate and remove drift in sports and for movements taking place outdoors in uncontrolled environments. Three different strategies were proposed to measure the movement of classical cross-country skiing and ski mountaineering, alpine ski racing, and outdoor walking over several kilometres. For each activity specific biomechanical constraints and movement dynamics were exploited. The proposed methods rely only on inertial sensors and magnetometers and are able to provide orientation, speed, and position information with an accuracy and precision close to existing gold standards. The most complete system was designed in alpine ski racing, probably one of the most challenging sports for movement analysis. Extreme vibrations, high speeds of over 120 km/h and a timing resolution below 0.01 seconds require maximum accuracy and precision. The athlete's posture and the kinematics of his centre of mass both in a relative athlete-centred frame and in a global Earth-fixed frame could be obtained with high accuracy and precision. Where 3D video analysis requires a very complex experimental setup and takes several hours of post processing to analyse a single turn of a skier, the proposed system allows to measure multiple athletes and complete runs within minutes. Thus, new experimental designs to assess performance and injury risk in alpine ski racing became feasible, greatly helping to gain further knowledge about this highly complex and risky sport

Further development and acceptability of a Sensorbased Movement Analysis Feedback Toolkit (SMAFT) for physiotherapy rehabilitation of people with knee pain

Background: Chronic knee pain is a common clinical symptom presented by individuals with musculoskeletal conditions. Chronic knee pain can have several significant physical and functional impacts on individuals, potentially resulting in reduced effectiveness of physiotherapy treatments and a lower quality of life. Limitations in functionality of the knee joint and physical activity may result from the alterations in movement presented in individuals with knee pain when performing everyday functional activities, as suggested by the pain adaptation theory. This theory proposes that unnecessary altered movement patterns can endure long-term, resulting in further pain and functional restrictions. Therefore, physiotherapy rehabilitation designed for individuals with knee pain should consider unnecessary altered movement patterns, by identifying and individualising treatments accordingly. This suggests a need for a portable clinic-based movement analysis system. Inertial measurement sensors could represent a promising movement analysis system within clinical practice, offering feedback about individuals’ kinematics and targeting treatment. Moreover, reporting and interpreting the huge volume of kinematic data provided by a three-dimensional (3D) movement analysis system is subjective and varied among its users, which might restrict its clinical access and utility. To eliminate this limitation, standardising the way of interpreting kinematic data designed in a user-friendly format is needed, which can enhance accuracy and consistency among users. Therefore, the aim of this PhD thesis is to further develop and evaluate the acceptability of a sensor-based movement analysis feedback toolkit (SMAFT) for clinical practice using an iterative process. Methods: This PhD thesis was undertaken in two phases. In the first phase, an exploratory study was conducted to inform the development of SMAFT. The study aimed to create a standardised reporting framework designed to improve clinicians’ accuracy and consistency when interpreting the kinematic data provided by a sensorbased movement analysis. Six raters, each with varying levels of experience in musculoskeletal clinical practice and movement analysis, were identified as participants. The raters interpreted 252 kinematic waveform graphs by identifying the presence of the altered movement patterns and describing them in writing. Withinand between-rater agreements were quantified using the observed agreement and Gwet's agreement coefficient, and the qualitative descriptions of the movement alterations were analysed using quantitative content analysis. This study was integrated with other developmental studies conducted by another PhD student to inform the development of a preliminary version of SMAFT. In the second phase, a mixed-methods case study was implemented to explore the acceptability of SMAFT when used alongside physiotherapy treatment as usual for individuals with knee pain within the physiotherapy clinical practice. The data was collected from multiple sources. Qualitative interviews for SMAFT’s users (individuals II with knee pain and clinicians) were analysed by employing a thematic analysis. Furthermore, quantitative descriptions of the individuals’ pain and function levels, their altered movement patterns identified, and their treatments given by clinicians were conducted. Results: In Phase one, the average score for the between-raters agreement when identifying the altered movement patterns was substantial (Gwet’s AC1 = 0.64) for all kinematic waveform graphs across all the lower limb joints, planes of movement, and functional tasks. The within-rater agreement presented a range from substantial to almost perfect agreement (Gwet’s AC1 = 0.70 – 0.99) across all the waveform graphs and over all joints, planes, and tasks. However, the way in which raters described and interpreted the identified movement alterations varied. Thus, a reporting template was created to standardise the process of interpreting the waveform graphs. The findings from this study were combined with other developmental studies to inform the development of a preliminary version of SMAFT that consists of portable inertial sensors, a movement analysis feedback report, avatar videos, and a standardised reporting template. This was used in Phase 2 to explore its acceptability among users within physiotherapy clinical practice. In phase two, integrating quantitative and qualitative components gave a more comprehensive view of SMAFT’s acceptability within clinical practice. The study’s findings suggested that the users showed broad acceptability towards the use of SMAFT alongside physiotherapy treatment from the perspective of being beneficial, practical, and usable. However, some challenges regarding its usability and practicality were identified. The findings afforded a clearer understanding of the design and delivery of SMAFT within clinical practice, which requires further refinements and investigations. Conclusion: The findings from the two phases of this PhD thesis contributed to the development of SMAFT to be used alongside physiotherapy treatment as usual for individuals with knee pain within clinical practice. A refined version of SMAFT was clearly described using the Template for Intervention Description and Replication (TIDier) checklist. Recommendations for the next stage of SMAFT development were also discussed