Type and Location of Wearable Sensors for Monitoring Falls during Static and Dynamic Tasks in Healthy Elderly: A Review <s> Two Sensors <s> Biofeedback is known to improve postural control and shorten rehabilitation periods among the young and elderly. A biofeedback system communicates with the human central nervous system through a variety of feedback modalities. Vibrotactile feedback devices are gaining attention due to their desirable characteristics and simplistic manner of presenting biofeedback. In this study, we investigate the potential of incorporating a real-time biofeedback system with artificial intelligence for wobble board training, aimed at improving ankle proprioception. The designed system utilizes vibrotactile actuators to provide forewarning for poor postural control. The biofeedback system depended on Euler angular measurements of trunk and wobble board displacements, from inertial measurement units (IMUs). A fuzzy inference system was used to determine the quality of postural control, based on IMU-acquired measurements of trunk and wobble board. The designed system integrates: 1) two IMUs, 2) a fuzzy knowledge base, and 3) a feedback-generation module. Tests were conducted in eyes-open and eyes-close conditions while standing on the wobble board to assess viability of the system in providing accurate real-time intervention. The results observed an improvement in postural control with biofeedback intervention, demonstrating successfulness of the prototype built for improving postural control in rehabilitative and preventive applications. <s> BIB001 </s> Type and Location of Wearable Sensors for Monitoring Falls during Static and Dynamic Tasks in Healthy Elderly: A Review <s> Two Sensors <s> Falls in the elderly are a major problem worldwide with enormous associated economic and societal costs. Minimum ground clearance (MGC) is an important gait variable when considering trip-related falls risk. This study aimed to investigate the clinical relevance of inertial sensor derived parameters, previously shown to be related to MGC. Previous research by the authors reported a surrogate method for assessing minimum ground clearance (MGC) using shank-mounted inertial sensors in young controls. The present study tests this method on a cohort of 114 community dwelling elderly adults, with and without a history of falls, completing a 30m continuous walk. Parameters based on the shank angular velocity signals that were shown to be associated with MGC showed significant differences (p<0.05) between fallers and non-fallers yet did not correlate strongly (r<0.7) with two standard measures of falls risk (TUG & BBS). Weak correlations were observed between the angular velocity derived parameters and gait velocity. We conclude that these parameters are clinically meaningful and therefore may constitute a new measure of falls risk. <s> BIB002 </s> Type and Location of Wearable Sensors for Monitoring Falls during Static and Dynamic Tasks in Healthy Elderly: A Review <s> Two Sensors <s> This study proposes a new robust classifier for sit-to-stand (SiSt) and stand-to-sit (StSt) detection in daily activity. The monitoring system consists of a single inertial sensor placed on the trunk. By using dynamic time warping, the trunk acceleration patterns of SiSt and StSi are classified based on their similarity with specific templates. The classification algorithm is validated with actual data obtained in a real-world environment (five healthy subjects and five chronic pain patients); the best accuracy is obtained through using a custom template defined for each subject ( > 95% for healthy subjects and 89% for chronic pain). Real-world examinations are found to be preferable because after validating results collected in both real-world and laboratory conditions, the controlled conditions' predictions are too optimistic. Finally, the potential of the new method in clinical evaluation is studied in both healthy and frail elderly subjects. Frail elderly participants show a significantly lower rate of postural transitions, longer SiSt duration, and lower SiSt trunk tilt and acceleration compared to healthy elderly subjects. We conclude that the proposed wearable system provides a simple method to detect and characterize postural transitions in healthy, chronic pain, and frail elderly subjects. <s> BIB003
By focusing on the papers that use two sensors, two families can be identified: approaches that combine the accelerometer with a pressure sensor (generally placed within the shoes), and methodologies that jointly use the accelerometer and the gyroscope sensors, usually placed on the same electronic board. For instance, the study proposed in BIB003 introduces a new robust classifier for sit-to-stand (SiSt) and stand-to-sit (StSi) detection in daily activity based on both gyroscope and accelerometer. The monitoring system consists of a single inertial sensor placed on the trunk. By using dynamic time warping, the trunk acceleration patterns of SiSt and StSi are classified based on their similarity to specific templates. Gopalai et al. BIB001 also use accelerometers and gyroscopes to improve postural control and shorten rehabilitation periods among the young and the elderly. Beyond such "standard" sensors, the use of some peculiar devices can be explored for the stability control of elderly people. Greene et al. BIB002 investigate the gait variable Minimum Ground Clearance (MGC) using shank-mounted inertial sensors containing both a tri-axial accelerometer and an add-on tri-axial gyroscope. The aim is to estimate clinically meaningful parameters, which may be used in the screening for falls risk.