Search results for "Accelerometers"

Characterization of MEMS accelerometer self-noise by means of PSD and Allan Variance analysis

2017

In this paper, we have studied the sources of error of a low-cost 3-axis MEMS accelerometer by means of Power Spectral Density and Allan Variance techniques. These techniques were applied to the signals acquired from ten identical devices to characterize the variability of the sensor produced by the same manufacturer. Our analysis showed as identically produced accelerometer have somehow variable behavior in particular at low frequency. It is therefore of paramount importance before their use in Inertial Navigation or Earthquakes Monitoring System, a complete characterization of each single sensors.

Experimental Investigation of the Modal Response of a Rail Span during and after Wheel Passage

2020

This paper examines the vibrations of a rail span (rail section between two consecutive sleepers) during and after the passage of a rail car’s wheel as well as under impact hammer excitation. In literature, the dynamic response of railway tracks under moving loads has been studied extensively. Many of these studies focus on the responses in relation to displacement/force-time histories and wave propagation parameters. These responses are investigated for the time instants when rail car wheels transverse over the rail spans of interest. In this context, an investigation of responses in relation to modal parameters during and after moving loads might provide additional information. Such info…

Influence of custom-made and prefabricated insoles before and after an intense run

2017

[EN] Each time the foot contacts the ground during running there is a rapid deceleration that results in a shock wave that is transmitted from the foot to the head. The fatigue of the musculoskeletal system during running may decrease the ability of the body to absorb those shock waves and increase the risk of injury. Insoles are commonly prescribed to prevent injuries, and both custom-made and prefabricated insoles have been observed to reduce shock accelerations during running. However, no study to date has included a direct comparison of their behaviour measured over the same group of athletes, and therefore great controversy still exists regarding their effectiveness in reducing impact …

Accelerometry - Simple, but challenging

2017

Directly measured and self-reported physical activity in a sample of Finnish secondary school students

2012

Background: Previous studies based on self-reports show that a majority of children and adolescents in Western countries fail to achieve the recommendation of 60 minutes moderate to vigorous physical activity (PA) on a daily basis. The specific aim of the study was to analyze the relationship between directly measured and self-reported PA in a cross-sectional sample of Finnish secondary school students. Moreover, how large proportion of adolescents accumulate at least 60 minutes of moderate to vigorous PA on a daily basis using self-reports and direct measure scores. Methods: Participants were recruited from a secondary school located in Northeast Finland. The sample comprised 96 students (…

Effect of a Service-Learning Program on the Active Lifestyle of Children with Autism Spectrum Disorder: A Pilot Study

2020

Background: active lifestyles and Physical Activity (PA) are closely related to health. Healthy habits such as being physically active should be consolidated during childhood. Children with Autism Spectrum Disorders (ASD) present fewer opportunities to be involved in PA. For this reason, we conducted a Service-Learning (SL) program to enhance the possibility of participating ASD children enjoying PA sessions. The aim of this study was to analyze and describe the evolution in terms of the frequency and intensity of PA performed by ASD children who participated in the SL program. Methods: we used a quasi-experimental design. The sample was formed by 26 children with ASD (Experimental group: n…

Wii-bändi : designing an expressive digital musical interface for therapeutic use with disabled people in a group setting

2011

This thesis presents the developmental prototype of a gesturally controlled digital musical interface. It is called Wii-bändi, as it uses Nintendo Wii controllers to translate the gestures into music, and is constructed specifically for clients with a variety of physical and mental disabilities so that they can use it in a therapeutic group context. It is argued that gestural and emotional expressivity might be based on a theory of vitality affects, and that optimal learnability could be achieved through making use of learning schemas. It then sets out how the interface was created using a methodological approach based on action research, describing the specific contexts that led to the cha…

Bearing fault detection based on time-frequency representations of vibration signals

2015

To prevent failures of a rolling bearing in the gearbox drive system, acceleration sensors are used to detect fault-related signals of the bearing. It is a big challenge to observe and identify signals caused by bearing defects in the time domain or the frequency spectrum by a conventional Fourier analysis. The time-frequency representation of the fault-related signals implemented by the windowed Fourier transform is studied in this work. It is shown that the fault characteristic frequencies can be clearly identified in the time-frequency spectrum if a fault occurs in the bearing of the gearbox at different speeds. Otherwise, the shaft frequency and its multiples are the main harmonics in t…

Use of accelerometers and gyros for hip and knee angle estimation

2013

In this paper a wearable sensor system, consisting of accelerometers and gyros, has been studied to estimate hip and knee angles. The proposed algorithm, developed in order to avoid the error accumulation due to gyroscopes drift, has been tested on angle measurement of the hip and knee of a commercial device for assisted gait. The results have shown a good accuracy of the angles estimation, also in high angle rate movement

Implementation of participatory sensing approach in mobile vehicle based sensor networks

2013

In this paper author describes his research with the goal to develop and experimentally verify specific data recording and processing methodologies based on participatory sensing approach implementation in mobile vehicle based sensor networks. To reach this goal, author performed study of literature, testing of hypothesis using general purpose computer devices, adaptation of smartphones for participatory sensing, development of special purpose embedded devices, practical experiments with selected technical equipment and software as well as gathering of experimental results and following statistical analysis. The result of this research are several data acquisition and processing methodologi…