Ground contact time (GCT) is one of the most relevant factors when assessing running performance ... more Ground contact time (GCT) is one of the most relevant factors when assessing running performance in sports practice. In recent years, inertial measurement units (IMUs) have been widely used to automatically evaluate GCT, since they can be used in field conditions and are friendly and easy to wear devices. In this paper we describe the results of a systematic search, using the Web of Science, to assess what reliable options are available to GCT estimation using inertial sensors. Our analysis reveals that estimation of GCT from the upper body (upper back and upper arm) has rarely been addressed. Proper estimation of GCT from these locations could permit an extension of the analysis of running performance to the public, where users, especially vocational runners, usually wear pockets that are ideal to hold sensing devices fitted with inertial sensors (or even using their own cell phones for that purpose). Therefore, in the second part of the paper, an experimental study is described. S...
In the context of human–robot collaborative shared environments, there has been an increase in th... more In the context of human–robot collaborative shared environments, there has been an increase in the use of optical motion capture (OMC) systems for human motion tracking. The accuracy and precision of OMC technology need to be assessed in order to ensure safe human–robot interactions, but the accuracy specifications provided by manufacturers are easily influenced by various factors affecting the measurements. This article describes a new methodology for the metrological evaluation of a human–robot collaborative environment based on optical motion capture (OMC) systems. Inspired by the ASTM E3064 test guide, and taking advantage of an existing industrial robot in the production cell, the system is evaluated for mean error, error spread, and repeatability. A detailed statistical study of the error distribution across the capture area is carried out, supported by a Mann–Whitney U-test for median comparisons. Based on the results, optimal capture areas for the use of the capture system a...
Journal of Ubiquitous Computing and Intelligence, Dec 1, 2007
Abstract: Ambient Intelligence is nowadays an active research field. As a key part of this concep... more Abstract: Ambient Intelligence is nowadays an active research field. As a key part of this concept, learning architectures for the control of the devices in an intelligent building must be developed, where the goal is to control the environment via a set of devices using an intelligent agent which should work in a non-intrusive manner to satisfy the preferences of the user. Mainly, we have focused our attention over fuzzy logic controllers (FLC) for the internal structure of the agent. The main motivation for the work described in this paper is ...
In human motion science, accelerometers are used as linear distance sensors by attaching them to ... more In human motion science, accelerometers are used as linear distance sensors by attaching them to moving body parts, with their measurement axes its measurement axis aligned in the direction of motion. When double integrating the raw sensor data, multiple error sources are also integrated integrated as well, producing inaccuracies in the final position estimation which increases fast with the integration time. In this paper, we make a systematic and experimental comparison of different methods for position estimation, with different sensors and in different motion conditions. The objective is to correlate practical factors that appear in real applications, such as motion mean velocity, path length, calibration method, or accelerometer noise level, with the quality of the estimation. The results confirm that it is possible to use accelerometers to estimate short linear displacements of the body with a typical error of around 4.5% in the general conditions tested in this study. However...
Pedometers are basically step counters usually used to estimate the distance walked by a pedestri... more Pedometers are basically step counters usually used to estimate the distance walked by a pedestrian. Although their precision to compute the number of steps is quite accurate (about 1%), their feasibility to estimate the walked distance is very poor, as they do not consider the intrinsic variability of human gait. Reported results show values of 10% of precision in optimal conditions, increasing to 50% when conditions differ. Electronic accelerometer-based pedometers base their functioning on a basic processing of the vertical acceleration of the waist. Recently, different approaches have been proposed to relate such signals to the step length. This can lead to an improvement of the performance of this kind of device for estimating the walked distance. In this article, we analyze four gait models applied to the vertical accelerations of the body's center of gravity, three biomechanical and one empirical. We compare their precision and accuracy. Results support the superior perfo...
Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2007
Step length estimation is an important issue in areas such as gait analysis, sport training or pe... more Step length estimation is an important issue in areas such as gait analysis, sport training or pedestrian localization. It has been shown that the mean step length can be computed by means of a triaxial accelerometer placed near the center of gravity of the human body. Estimations based on the inverted pendulum model are prone to underestimate the step length,
2003 IEEE International Conference on Robotics and Automation (Cat. No.03CH37422), 2003
Abstract Robot Navigation is an especially challenging problem when only online sensor informatio... more Abstract Robot Navigation is an especially challenging problem when only online sensor information is available. The main problem is to guarantee global properties, such as algorithm convergence or trajectory optimality, based on local information. In this paper ...
2012 IEEE International Instrumentation and Measurement Technology Conference Proceedings, 2012
We present a waist-worn personal navigation system based on inertial measurement units. The devic... more We present a waist-worn personal navigation system based on inertial measurement units. The device makes use of the human bipedal pattern to reduce position error. We describe improved algorithms, based on detailed description of the heel strike biomechanics and its translation to accelerations of the body waits, to estimate the periods of zero velocity, the step length, and the heading
2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2007
Walking distance estimation is an important issue in areas such as gait analysis, sport training ... more Walking distance estimation is an important issue in areas such as gait analysis, sport training or pedestrian localization. A natural location for portable inertial sensors for gait monitoring is to attach them to the user shoes. Step length can be computed by means of a biaxial accelerometer and a gyroscope on the sagittal plane. But estimations based on the direct signal integration are prone to error. This paper shows the results achieved by using a multisensor model approach to reduce uncertainty. Unbounded growth of error is reduced by means of sensor fusion techniques. The method has been tested, and early experimental results show that it provides an estimation of the walking distance with a standard deviation smaller than with single IMU similar systems.
2012 IEEE International Instrumentation and Measurement Technology Conference Proceedings, 2012
In order to make an ergonomic analysis of laborer working conditions, we need to measure the diff... more In order to make an ergonomic analysis of laborer working conditions, we need to measure the different joint angles along the daily work. These angles will be used to define the requirements of each workstation. This information, together with the medical examination of each worker, is then used to determine whether a worker can develop a task, or if the
In this paper we propose an approach for the estimation of the slope of the walking surface durin... more In this paper we propose an approach for the estimation of the slope of the walking surface during normal walking using a body-worn sensor composed of a biaxial accelerometer and a uniaxial gyroscope attached to the shank. It builds upon a state of the art technique that was successfully used to estimate the walking velocity from walking stride data, but did not work when used to estimate the slope of the walking surface. As claimed by the authors, the reason was that it did not take into account the actual inclination of the shank of the stance leg at the beginning of the stride (mid stance). In this paper, inspired by the biomechanical characteristics of human walking, we propose to solve this issue by using the accelerometer as a tilt sensor, assuming that at mid stance it is only measuring the gravity acceleration. Results from a set of experiments involving several users walking at different inclinations on a treadmill confirm the feasibility of our approach. A statistical analysis of slope estimations shows in first instance that the technique is capable of distinguishing the different slopes of the walking surface for every subject. It reports a global RMS error (per-unit difference between actual and estimated inclination of the walking surface for each stride identified in the experiments) of 0.05 and this can be reduced to 0.03 with subject-specific calibration and post processing procedures by means of averaging techniques.
Wearable accelerometry provides easily portable systems that supply real-time data adequate for g... more Wearable accelerometry provides easily portable systems that supply real-time data adequate for gait analysis. When they do not provide direct measurement of a spatio-temporal parameter of interest, such as step length, it has to be estimated with a mathematical model from indirect sensor measurements. In this work we are concerned with the accelerometry-based estimation of the step length in straight line human walking. We compare five step length estimators. Measurements were taken from a group of four adult men, adding up a total of 800 m per individual of walking data. Also modifications to these estimators are proposed, based on biomechanical considerations. Results show that this modifications lead to improvements of interest over previous methods
Ground contact time (GCT) is one of the most relevant factors when assessing running performance ... more Ground contact time (GCT) is one of the most relevant factors when assessing running performance in sports practice. In recent years, inertial measurement units (IMUs) have been widely used to automatically evaluate GCT, since they can be used in field conditions and are friendly and easy to wear devices. In this paper we describe the results of a systematic search, using the Web of Science, to assess what reliable options are available to GCT estimation using inertial sensors. Our analysis reveals that estimation of GCT from the upper body (upper back and upper arm) has rarely been addressed. Proper estimation of GCT from these locations could permit an extension of the analysis of running performance to the public, where users, especially vocational runners, usually wear pockets that are ideal to hold sensing devices fitted with inertial sensors (or even using their own cell phones for that purpose). Therefore, in the second part of the paper, an experimental study is described. S...
In the context of human–robot collaborative shared environments, there has been an increase in th... more In the context of human–robot collaborative shared environments, there has been an increase in the use of optical motion capture (OMC) systems for human motion tracking. The accuracy and precision of OMC technology need to be assessed in order to ensure safe human–robot interactions, but the accuracy specifications provided by manufacturers are easily influenced by various factors affecting the measurements. This article describes a new methodology for the metrological evaluation of a human–robot collaborative environment based on optical motion capture (OMC) systems. Inspired by the ASTM E3064 test guide, and taking advantage of an existing industrial robot in the production cell, the system is evaluated for mean error, error spread, and repeatability. A detailed statistical study of the error distribution across the capture area is carried out, supported by a Mann–Whitney U-test for median comparisons. Based on the results, optimal capture areas for the use of the capture system a...
Journal of Ubiquitous Computing and Intelligence, Dec 1, 2007
Abstract: Ambient Intelligence is nowadays an active research field. As a key part of this concep... more Abstract: Ambient Intelligence is nowadays an active research field. As a key part of this concept, learning architectures for the control of the devices in an intelligent building must be developed, where the goal is to control the environment via a set of devices using an intelligent agent which should work in a non-intrusive manner to satisfy the preferences of the user. Mainly, we have focused our attention over fuzzy logic controllers (FLC) for the internal structure of the agent. The main motivation for the work described in this paper is ...
In human motion science, accelerometers are used as linear distance sensors by attaching them to ... more In human motion science, accelerometers are used as linear distance sensors by attaching them to moving body parts, with their measurement axes its measurement axis aligned in the direction of motion. When double integrating the raw sensor data, multiple error sources are also integrated integrated as well, producing inaccuracies in the final position estimation which increases fast with the integration time. In this paper, we make a systematic and experimental comparison of different methods for position estimation, with different sensors and in different motion conditions. The objective is to correlate practical factors that appear in real applications, such as motion mean velocity, path length, calibration method, or accelerometer noise level, with the quality of the estimation. The results confirm that it is possible to use accelerometers to estimate short linear displacements of the body with a typical error of around 4.5% in the general conditions tested in this study. However...
Pedometers are basically step counters usually used to estimate the distance walked by a pedestri... more Pedometers are basically step counters usually used to estimate the distance walked by a pedestrian. Although their precision to compute the number of steps is quite accurate (about 1%), their feasibility to estimate the walked distance is very poor, as they do not consider the intrinsic variability of human gait. Reported results show values of 10% of precision in optimal conditions, increasing to 50% when conditions differ. Electronic accelerometer-based pedometers base their functioning on a basic processing of the vertical acceleration of the waist. Recently, different approaches have been proposed to relate such signals to the step length. This can lead to an improvement of the performance of this kind of device for estimating the walked distance. In this article, we analyze four gait models applied to the vertical accelerations of the body's center of gravity, three biomechanical and one empirical. We compare their precision and accuracy. Results support the superior perfo...
Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2007
Step length estimation is an important issue in areas such as gait analysis, sport training or pe... more Step length estimation is an important issue in areas such as gait analysis, sport training or pedestrian localization. It has been shown that the mean step length can be computed by means of a triaxial accelerometer placed near the center of gravity of the human body. Estimations based on the inverted pendulum model are prone to underestimate the step length,
2003 IEEE International Conference on Robotics and Automation (Cat. No.03CH37422), 2003
Abstract Robot Navigation is an especially challenging problem when only online sensor informatio... more Abstract Robot Navigation is an especially challenging problem when only online sensor information is available. The main problem is to guarantee global properties, such as algorithm convergence or trajectory optimality, based on local information. In this paper ...
2012 IEEE International Instrumentation and Measurement Technology Conference Proceedings, 2012
We present a waist-worn personal navigation system based on inertial measurement units. The devic... more We present a waist-worn personal navigation system based on inertial measurement units. The device makes use of the human bipedal pattern to reduce position error. We describe improved algorithms, based on detailed description of the heel strike biomechanics and its translation to accelerations of the body waits, to estimate the periods of zero velocity, the step length, and the heading
2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2007
Walking distance estimation is an important issue in areas such as gait analysis, sport training ... more Walking distance estimation is an important issue in areas such as gait analysis, sport training or pedestrian localization. A natural location for portable inertial sensors for gait monitoring is to attach them to the user shoes. Step length can be computed by means of a biaxial accelerometer and a gyroscope on the sagittal plane. But estimations based on the direct signal integration are prone to error. This paper shows the results achieved by using a multisensor model approach to reduce uncertainty. Unbounded growth of error is reduced by means of sensor fusion techniques. The method has been tested, and early experimental results show that it provides an estimation of the walking distance with a standard deviation smaller than with single IMU similar systems.
2012 IEEE International Instrumentation and Measurement Technology Conference Proceedings, 2012
In order to make an ergonomic analysis of laborer working conditions, we need to measure the diff... more In order to make an ergonomic analysis of laborer working conditions, we need to measure the different joint angles along the daily work. These angles will be used to define the requirements of each workstation. This information, together with the medical examination of each worker, is then used to determine whether a worker can develop a task, or if the
In this paper we propose an approach for the estimation of the slope of the walking surface durin... more In this paper we propose an approach for the estimation of the slope of the walking surface during normal walking using a body-worn sensor composed of a biaxial accelerometer and a uniaxial gyroscope attached to the shank. It builds upon a state of the art technique that was successfully used to estimate the walking velocity from walking stride data, but did not work when used to estimate the slope of the walking surface. As claimed by the authors, the reason was that it did not take into account the actual inclination of the shank of the stance leg at the beginning of the stride (mid stance). In this paper, inspired by the biomechanical characteristics of human walking, we propose to solve this issue by using the accelerometer as a tilt sensor, assuming that at mid stance it is only measuring the gravity acceleration. Results from a set of experiments involving several users walking at different inclinations on a treadmill confirm the feasibility of our approach. A statistical analysis of slope estimations shows in first instance that the technique is capable of distinguishing the different slopes of the walking surface for every subject. It reports a global RMS error (per-unit difference between actual and estimated inclination of the walking surface for each stride identified in the experiments) of 0.05 and this can be reduced to 0.03 with subject-specific calibration and post processing procedures by means of averaging techniques.
Wearable accelerometry provides easily portable systems that supply real-time data adequate for g... more Wearable accelerometry provides easily portable systems that supply real-time data adequate for gait analysis. When they do not provide direct measurement of a spatio-temporal parameter of interest, such as step length, it has to be estimated with a mathematical model from indirect sensor measurements. In this work we are concerned with the accelerometry-based estimation of the step length in straight line human walking. We compare five step length estimators. Measurements were taken from a group of four adult men, adding up a total of 800 m per individual of walking data. Also modifications to these estimators are proposed, based on biomechanical considerations. Results show that this modifications lead to improvements of interest over previous methods
Uploads