A portable system with sample rate of 250 Hz for characterization of knee and hip angles in the sagittal plane during gait.

BACKGROUND: Gait analysis and research have been developed to obtain characteristics of movement patterns of people while walking. However, traditional measuring systems present different drawbacks that reduce their use and application. Among those drawbacks one can find: high price, low sampling frequency and limiting number of steps to be analyzed. Traditional measuring gait systems carry out their measurement at frequencies oscillating between 60 to 100 Hz. It can be argued about the need of higher sampling rates for gait measurements. However small displacements of the knee or hip for example, cannot be seen with low frequencies required a more detailed sampling and higher frequency sampling. Bearing this in mind, in this paper is presented a 250 Hz system based on accelerometers for gait measurement, and the particularities of knee and hip angles during gait are highlighted. METHODS: The system was designed with a PCI data acquisition card instrumented with an FPGA to achieve a rate sample of 250 Hz. The accelerometers were placed in thighs and legs to calculate the joint angles of hip and knee in the sagittal plane. The angles were estimated using the acceleration polygon method without integrating the acceleration and without filters. RESULTS: The gait of thirty healthy people of Mexican phenotype was analyzed over a flat floor free of obstacles. The results showed the gait phases and particularities associated with the walking style and people's laterality; the movement patterns were similar in the thirty persons. Based on the results, the particularities as the maximum amplitude in the angles and the shape in the movement patterns were related to the anthropometry and people phenotype. CONCLUSIONS: The sampling frequency was essential to record 340 samples in single gait cycle and so registering the gait cycle with its particularities. In this work were recorded an average of 8 to 10 gait cycles, and the results showed variation regarding works carried out in biomechanics laboratories; this variation was related to the method and reference frame used to obtain the joint angles and the accuracy of measurement system.

Intelligent interface for data acquisition and transmission from a neutron generator to a computer through an optical fibre / Interfase inteligente para adquirir y transmitir desde un generador de neutrones a un computador a través de una fibra óptica

The present paper shows the design, construction and application of an interface developed on the base of the microcontroller usage. The aim is to reestablish the communication exchange among the basic modules that constitute the Neutron Generator belonging to the CEADEN Physics Department. Original interface design is upgraded by the automation of the data acquisition on the Neutron Generator exploitation parameters. The data acquisition card, optoelectronic converters, a PC-user interface using Lab VIEW environment, the indispensable firmware for interface functioning were developed for that purpose. The use of PC in the Neutron Generator is introduced, thus setting a precedent for the further automation of other subsystems.

Se presenta el diseño, construcción y aplicación de una interfase desarrollada utilizando microcontroladores, con el fin de restablecer la comunicación entre los módulos básicos que componen el generador de neutrones del Departamento de Física del Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear. Se moderniza la interfase original automatizando la adquisición de la información sobre los parámetros de explotación del generador de neutrones. Se desarrolló la tarjeta de adquisición de las señales de interés, los conversores opto electrónicos, la interfase PC-usuario en ambiente LabView y los códigos indispensables para el funcionamiento de la interfase. Se introdujo el uso de la PC en el generador de neutrones y se estableció el antecedente para extender la automatización a otros subsistemas de la instalación.