Sensor-to-body calibration procedure and definition of anatomical references for gait analysis based on inertial sensors

• Autor(a) principal: Valencia, Laura Susana Vargas
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/9658
• topic: Sensores inerciais; Unidade de medição inercial (IMU); Engenharia Elétrica; Marcha humana; Articulações; Cinemática; Calibração; 621.3

Recently, inertial measurement units (IMU) are placed on the human body segments in order to estimate joints kinematics. A fundamental issue in human gait analysis based on IMUs is that sensors' local references frames are misaligned with anatomically-defined body-segments' frames. Thus, this M.Sc. Dissertation proposes the development of a calibration procedure to address the problem of sensor-to-body alignment in order to estimate joint angular kinematics during free walking. The novel, simple and fast calibration procedure provides tridimensional kinematics of hip, knee and ankle using only four IMUs, without resorting to any additional tools or predefined movements. A method for static assessment of the IMUs was conducted in order to determine the initial state of the system. The algorithms to align the sensors to the body segments, to calculate the joint angles and to detect events such as heel strike and toe off are also presented. Experiments were performed with five healthy subjects and the results were compared with similar studies found in the literature. The results presented low standard deviations, which means that estimated measures were consistent across trials. The angular patterns are coherent and consistent with those presented in the literature. This procedure also presents the potential to become an alternative to high-cost camera-based systems allowing the possibility of performing the analysis of human gait in external environments with clinical application in the near future.