Uso de sensores inerciales en fisioterapia: Una aproximación a procesos de evaluación del movimiento humano / Use of inertial sensors in physiotherapy: an approach to human movement assessment processes

Resumen Introducción: Los sensores inerciales o unidad de medición inercial (IMU) del inglés Inertial measurement unit, son pequeños dispositivos capaces de medir la aceleración lineal y la velocidad angular, siendo útiles en el área de la salud para la cuantificación y valoración objetiva del movimiento corporal humano. Objetivo: Analizar la información sobre el uso de sensores inerciales como una aproximación a los procesos de evaluación del movimiento corporal humano. Materiales y métodos: Se realizó búsqueda en bases de datos, empleando términos: sensores inerciales, salud, fisioterapia, acelerómetro, actividad física, movimiento y rehabilitación, y sus combinaciones. Como criterios de exclusión se tuvo: artículos exclusivos del campo de ingeniería con información no aplicable a fisioterapia. Resultados: Una IMU es compatible con aplicaciones (APP), con el objetivo de obtener datos de movimiento tridimensionales y como evaluación e intervención, o que permita cuantificar los resultados de la acción motora. Conclusiones: Las IMU tienen amplias posibilidades en áreas afines a la rehabilitación y otras referentes al entrenamiento y el área deportiva; por lo, cual es necesario estandarizar protocolos que permitan la medición de patrones motores que favorezcan los procesos de rehabilitación.

Abstract Introduction: Inertial measurement units (IMU) are small devices capable of measuring linear acceleration and angular velocity. Therefore, they are useful in the health field for the quantification and objective assessment of the human body movement. Objective: To analyze information about the inertial sensors usage, as a way to approach to processes of evaluation of the human body movement. Materials and methods: A database search was performed, using the following terms: inertial sensors, health, physiotherapy, accelerometer physical activity, movement, rehabilitation and their multiple combinations. The exclusion criteria were exclusive articles from the engineering field covering information not relevant for physical therapy. Results: IMUs are devices that are compatible with applications, which can obtain three-dimensional movement data. They can also be used for assessment and intervention to quantify results of motor action. Conclusions: IMUs may have wide applications in fields such as rehabilitation, training and sports. As a result, it is necessary to standardize protocols to measure motor patterns and facilitate rehabilitation processes.

Freezing of Gait Detection System for Parkinson's Patients Based on Inertial Measurement Unit / 中国医疗器械杂志

In order to detect freezing of gait of Parkinson's patients automatically, a system based on inertial measurement unit to detect freezing of gait for Parkinson's patients is established. The two inertial measurement units are respectively fixed on the left and right ankles of the patient to be measured, the freezing index is calculated by windowed Fourier transform, the freezing threshold is calculated based on the freezing index during normal walking, and the freezing index and the freezing threshold are compared to complete the detection of freezing of gait. The experimental results show that the number of freezing of gait occurrences in Parkinson's patients is accurately detected, and it has high sensitivity and specificity, which can assist doctors to objectively assess the patient's condition.

Evaluation of Validity and Reliability of Inertial Measurement Unit-Based Gait Analysis Systems

OBJECTIVE: To replace camera-based three-dimensional motion analyzers which are widely used to analyze body movements and gait but are also costly and require a large dedicated space, this study evaluates the validity and reliability of inertial measurement unit (IMU)-based systems by analyzing their spatio-temporal and kinematic measurement parameters. METHODS: The investigation was conducted in three separate hospitals with three healthy participants. IMUs were attached to the abdomen as well as the thigh, shank, and foot of both legs of each participant. Each participant then completed a 10-m gait course 10 times. During each gait cycle, the hips, knees, and ankle joints were observed from the sagittal, frontal, and transverse planes. The experiments were conducted with both a camerabased system and an IMU-based system. The measured gait analysis data were evaluated for validity and reliability using root mean square error (RMSE) and intraclass correlation coefficient (ICC) analyses. RESULTS: The differences between the RMSE values of the two systems determined through kinematic parameters ranged from a minimum of 1.83 to a maximum of 3.98 with a tolerance close to 1%. The results of this study also confirmed the reliability of the IMU-based system, and all of the variables showed a statistically high ICC. CONCLUSION: These results confirmed that IMU-based systems can reliably replace camera-based systems for clinical body motion and gait analyses.

Validation of foot pitch angle estimation using inertial measurement unit against marker-based optical 3D motion capture system

Gait analysis is relevant to a broad range of clinical applications in areas of orthopedics, neurosurgery, rehabilitation and the sports medicine. There are various methods available for capturing and analyzing the gait cycle. Most of gait analysis methods are computationally expensive and difficult to implement outside the laboratory environment. Inertial measurement units, IMUs are considered a promising alternative for the future of gait analysis. This study reports the results of a systematic validation procedure to validate the foot pitch angle measurement captured by an IMU against Vicon Optical Motion Capture System, considered the standard method of gait analysis. It represents the first phase of a research project which aims to objectively evaluate the ankle function and gait patterns of patients with dorsiflexion weakness (commonly called a “drop foot”) due to a L5 lumbar radiculopathy pre- and post-lumbar decompression surgery. The foot pitch angle of 381 gait cycles from 19 subjects walking trails on a flat surface have been recorded throughout the course of this study. Comparison of results indicates a mean correlation of 99.542% with a standard deviation of 0.834%. The maximum root mean square error of the foot pitch angle measured by the IMU compared with the Vicon Optical Motion Capture System was 3.738° and the maximum error in the same walking trail between two measurements was 9.927°. These results indicate the level of correlation between the two systems.

Research progress of human's attitude angle measurement methods based on inertial sensors / 医疗卫生装备

Multiple methods of attitude measureinent based on inertial measurement unit (IMU) were summarized.The single sensor's means of attitude measurement and it's relative merits were introduced.What's more,the combined method applied to attitude measurement were highlightedly mentioned.In addition,the ways of attitude measurement with multi-sensors units were listed.It also gave useful recommendations for better selection with regard to specific application.The prospect of IMU applied on human bodies was analysed.

Inertial Measurement Unit and Fall Risk Assessment in the Elderly (review) / 中国康复理论与实践

Falling in the elderly is a major health problem and may cause severe consequences. Fall risk assessment is important for pre-venting and intervening fall incidence. Inertial Measurement Unit (IMU) has been introduced to evaluate motion/balance function and fall risk among the older people. Some researches indicated that it might have advantages over the usual tools, and can be used in the hospitals, communities, nursing homes, etc. IMU is a good way to measure gait variability, which may be strongly related with the risk of falls.

Inertial Measurement Unit and Fall Risk Assessment in the Elderly (review) / 中国康复理论与实践

@#Falling in the elderly is a major health problem and may cause severe consequences. Fall risk assessment is important for preventing and intervening fall incidence. Inertial Measurement Unit (IMU) has been introduced to evaluate motion/balance function and fall risk among the older people. Some researches indicated that it might have advantages over the usual tools, and can be used in the hospitals, communities, nursing homes, etc. IMU is a good way to measure gait variability, which may be strongly related with the risk of falls.

Instantaneous Position and Orientation of the Body Segments as an Arbitrary Object in 3D Space by Merging Gyroscope and Accelerometer Information / Posición y orientación instantánea de los segmentos corporales como un objeto arbitrario en el espacio 3D a través de la fusión de la información de acelerómetros y giroscopios

This work presents an algorithm to determine instantaneous orientation of an object in 3D space. The orientation was determined by using a Direction Cosine Matrix (DCM), performed by the combination of three consecutive rotations, around each to the main axes of the evaluated system, using quaternions. An inertial measurement unit (IMU), consisting of 3 axes gyroscope and 3 axes accelerometer was used in order to establish 2 coordinate systems; The first one describes object movement, by using gyroscope as a main source of information, relating the angular rate of change along time. The second defines a coordinate reference system, relating the acceleration of gravity to an inertial direction vector. A proportional integral (PI) feedback controller was used, which includes sensors information, eliminating offset, cancelling drift and improving the accuracy of the orientation. The proposed algorithm can be used for assessing both the position and orientation of the body segments which is very important in orthopedic, traumatology and rheumatology important for diagnosis, prognostic, therapeutic, research and as well as the design and fabrication of measuring devices used in surgical instrumentation, prostheses and ortheses. It is important to note that the developed system opens the opportunities to be implemented on ambulatory joint evaluation through a wearable system, due to the dimensions and requirements of the sensors.

El presente trabajo presenta un algoritmo para determinar la orientación instantánea de un objeto en el espacio 3D. La orientación fue determinada utilizando una matriz de cosenos directores (DCM) conformada por la combinación de 3 rotaciones consecutivas alrededor de cada uno de los ejes del sistema evaluado, utilizando cuaterniones. Una unidad inercial de medida (IMU) compuesta por un giroscopio de 3 ejes y un acelerómetro de 3 ejes fue utilizada con el objetivo de establecer 2 sistemas coordenados; Un sistema coordenado describiendo el movimiento del objeto, utilizando al giroscopio como fuente principal de información, estableciendo la relación de cambio con respecto al tiempo. Un sistema coordenado de referencia, relacionando la aceleración gravitacional a un vector inercial. Un control por retroalimentación proporcional integral (PI) fue utilizado con el objetivo de combinar la información de los sensores, eliminando las desviaciones por offset y deriva, mejorando la precisión en la orientación. Dadas sus características, el algoritmo propuesto permite su utilización en la evaluación de la posición y la orientación de los segmentos corporales, siendo de suma importancia en ortopedia, traumatología y reumatología para la determinación de diagnósticos, pronósticos terapéuticos e investigación así como el diseño y fabricación de dispositivos de medición, instrumentación quirúrgica, prótesis y ortesis. Cabe destacar que el sistema desarrollado abre oportunidades de ser implementado en el diseño de sistemas ambulatorios de evaluación de las articulaciones, mediante el uso de elementos transportables dadas las reducidas dimensiones y limitaciones de los sensores empleados.