Andrea Cristiani

A Real-Time and Self-Calibrating Algorithm Based on Triaxial Accelerometer Signals for the Detection of Human Posture and Activity

Assessment of human activity and posture with triaxial accelerometers provides insightful information about the functional ability: classification of human activities in rehabilitation and elderly surveillance contexts has been already proposed in the literature. In the meanwhile, recent technological advances allow developing miniaturized wearable devices, integrated within garments, which may extend this assessment to novel tasks, such as real-time remote surveillance of workers and emergency operators intervening in harsh environments. We present an algorithm for human posture and activity-level detection, based on the real-time processing of the signals produced by one wearable triaxial accelerometer. The algorithm is independent of the sensor orientation with respect to the body. Furthermore, it associates to its outputs a “reliability” value, representing the classification quality, in order to launch reliable alarms only when effective dangerous conditions are detected. The system was tested on a customized device to estimate the computational resources needed for real-time functioning. Results exhibit an overall 96.2% accuracy when classifying both static and dynamic activities.

Design and Development of a Monitoring System for the Interface Pressure Measurement of Seated People

This paper illustrates the design and realization of a novel measurement system for the acquisition and dynamic analysis of interface pressure data and continuous monitoring of the center of pressure of a seated person. The system is composed of a capacitive sensor matrix, the electronics for the acquisition and preprocessing of the signal, and a software application for displaying data on a personal computer screen. The scope of this device is to obtain a system that is able to detect important parameters without being perceived by the subject and to evaluate the feeling of discomfort, pain and, eventually, to early detect the development of pressure ulcers. The continuous and automatic measurement of the individuals movements contributes to the assessment of the psychological-physical condition of the person and in particular to the detection of the level of comfort and discomfort during long periods of sitting.

An Instrumented Insole for Long Term Monitoring Movement, Comfort, and Ergonomics

We present a new electronic insole for wireless monitoring of motor activities and shoe comfort. The proposed device, equipped with both ZigBee transmission and local data storage allows unobtrusive, long term monitoring of subjects outside the laboratory, during natural behavior activites, such as daily living and sports. The system detailed in this work includes humidity and temperature sensors, as well as a three axis accelerometer and four pressure sensors, all fitted within a 3.7 mm thick insole. Preliminary experiments have shown that the device is reliable and may be worn without causing discomfort even for long periods of time, suggesting that it could be useful in applications ranging from ergonomics studies on footwear to sports and rehabilitation.

A Wearable and Modular Inertial Unit for Measuring Limb Movements and Balance Control Abilities

Measuring human movement has many useful applications ranging from fall risk assessment, quantifying sports exercise, studying people habits, and monitoring the elderly. Here, we present a versatile, wearable device based on a 9-degrees-of-freedom inertial measurement unit conceived for providing objective measurements of trunk or limb movements for the assessment of motor and balance control abilities. The proposed device measures linear accelerations, angular velocities, and heading and can be configured to either wirelessly transmit the raw or preprocessed data to a computer for online use, e.g., visualization or further processing, or to store the acquired data locally for long-term monitoring during free movement. Furthermore, the device can work in either single sensor or multiple sensors configuration, to simultaneously record several body parts for monitoring full body kinematics. Here, we compare body sway and trunk kinematic data computed based on our sensor with those based on the data from a force platform and a marker-based motion tracker, respectively, during the evaluation of both static and dynamic exercises drawn from clinical balance scales. Results from these experiments on two populations of healthy subjects are encouraging and suggest that the proposed device can effectively be used for measuring limb movements and to assess balance control abilities.

Design and development of a novel capacitive sensor matrix for measuring pressure distribution

This work illustrates the design and realization of a mattress made of capacitive sensors that measures the pressure distribution and the center of pressure of a person, while driving a car for long periods of time. The scope of this device is to obtain a system able to detect important parameters without being perceived by the subject. The continuous and automatic measurement of the individuals movements contributes in the assessment of the psyco-physical condition of the driver, mainly regarding the level of discomfort, which influences the degree of fatigue and, as a consequence, the concentration of the subject.

Driver Drowsiness Identification by Means of Passive Techniques for Eye Detection and Tracking

The aim of this paper is to describe a system whose final goal is to detect if a driver is drowsy, in order to prevent potentially danger situations. The system is based on the processing of the driver’s face image, acquired by a web cam installed on the dashboard of the car. After a brief introduction explaining the connection of the present work to the European project REFLECT, the relashonship between drowsiness condition and fatal car crashes is dicussed. Then, an overview of the most used techiques for face and eye detection is given, and the developed algorithm is described in detail. Finally, preliminary results of in-laboratory and in-car tests are presented and commented.

Self-Adaptive Prototype for Seat Adaption

Self-adaptive prototype for seat adaptation aims at enhancing the physical comfort of a driver by taking into account not only the state of the environment (state of the road, car settings), but also the driver’s emotional, cognitive and physical state. To implement this prototype we used a REFLECTive middleware, which provides a programming framework for the development of pervasive-adaptive applications. The REFLECTive middleware supports self-adaptive behavior and is generally composed of three tiers: Tangible tier contains services that read sensors data and send commands to actuators, REFLECTive tier is responsible for analyzing the data collected from sensors and for defining the actions that will be performed by actuators, Application tier facilitates high-level decision making. The seat adaptation prototype uses the information about Center of Pressure (COP) speed and number of bumps to determine the driver’s physical state, and then it combines this information with the driver’s cognitive and emotional state to figure out if the driver feels uncomfortable, and to change the state of seat cushions in an attempt to make driver feel more comfortable. The components of the seat adaptation prototype in the REFLECTive and Application tier are implemented using reaction rules.

A Multi-Purpose Wireless Sensor Network Based on Zigbee Technology

Among a wide offer of wireless technologies, ZigBee is one of the most actractive for connecting low–volume devices, such as sensors. This paper aims at presenting a project which is being carried on at Microcomputers and Biomedical Devices laboratory (Department of Computer Science, Faculty of Engineering, University of Pavia, Italy). The goal of the project is the development of a prototype of ZigBee sensors network for temperature monitoring. The idea is to evaluate the capability of ZigBee technology in order to build wireless sensors networks for environmental monitoring. The use of a single chip which integrates a microcontroller and a ZigBee transceiver gives the possibility of developing wireless devices with small dimensions, low power consumption, and a good computing capability.

A Portable System for Measuring Human Body Movement

A low cost portable acquisition system for monitoring and processing human body segment movements is presented It is equipped with 32 multiplexed input channels, each one linked to an external 2 axis MEMS accelerometer. Input signals from sensors are converted into a digital form by a 10 bit analog to digital converter and transmitted via Bluetooth technology to a remote PC. The instrument is battery powered and then it can be used in applications like ergonomics, rehabilitation and sport medicine. Labview 7.1 has been used to visualize in real time the human body segment movements

A wearable system for measuring limb movements and balance control abilities based on a modular and low-cost inertial unit.

Monitoring balance and movement has proven useful in many applications ranging from fall risk assessment, to quantifying exercise, studying people habits and monitoring the elderly. Here we present a versatile, wearable instrument capable of providing objective measurements of limb movements for the assessment of motor and balance control abilities. The proposed device allows measuring linear accelerations, angular velocities and heading either online, through wireless connection to a computer, or for long-term monitoring, thanks to its local storage abilities. One or more body parts may be simultaneously monitored in a single or multiple sensors configuration.