Validation of the ambient TUG chair with light barriers and force sensors in a clinical trial

Abstract

To initiate appropriate interventions and avoid physical decline, comprehensive measurements are needed to detect functional changes in elderly people at the earliest possible stage. The established Timed Up&Go (TUG) test takes little time and, due to its standardized and easy procedure, can be conducted by elderly people in their own homes without clinical guidance. Therefore, cheap light barriers (LBs) and force sensors (FSs) are well suited ambient sensors that could easily be attached to existing (arm)chairs to measure and report TUG times in order to identify functional decline. We validated the sensitivity of these sensors in a clinical trial with 100 elderlies aged 58-92 years with a mean of 74 (±6.78) years by comparing the sensor-based results with standard TUG measurements using a stopwatch. We further evaluated the accuracy enhancement when calibrating the algorithm via a mixed linear model. With calibration, the LBs achieved a root mean square error (RMSE) of 0.83 s, compared to 1.90 s without, and the FSs achieved 0.90 s compared to 2.12 s without. The suitability of measuring accurate TUG times with each of the ambient sensors and of measuring TUG regularly in the homes of elderly people could be confirmed.

Measurement System for Unsupervised Standardized Assessment of Timed “Up & Go” and Five Times Sit to Stand Test in the Community—A Validity Study

“…The LB bias resulted from the LB not measuring initial reaction times. The findings agreed with a corresponding previous study [24]. The negative mean difference of the IMU might result from the sensor's higher sensitivity to initial movements of the upper body and the delayed reaction times of the study nurse handling the stopwatch.…”

“…The USS (shown in Figure 1) monitored user movements via the following sensors: the aTUG chair [24] (c), a hip-worn inertial sensor (d), light barriers (e, c), and the Intel R RealSense TM D435 depth image cameras (f).…”

“…Applying automated assessments via technical screening systems such as the ambient TUG (aTUG) chair has been confirmed to be sensitive to detect functional decline [24], and it is also assumed to increase the intra-test reliability among consecutive measures. While still requiring the presence of a supervisor for advising on the procedure and supervision of correct execution, the aTUG includes already automated measuring functionality.…”

Towards an Automated Unsupervised Mobility Assessment for Older People Based on Inertial TUG Measurements

“…Especially the transitions (sit-to-stand, stand-to-sit) can be analyzed by these sensors. The TUG duration analysis by force sensors achieved a root mean square error (RMSE) of 0.90 s after calibration [ 8 ]. The laser range scanner (Hokuyo UTM-30LX, Hokuyo Automatic Co., Ltd., Osaka, Japan) was used for gait analyses during the walking phases and the turning.…”

“…The automated/ambient TUG (aTUG) [ 7 ] uses ambient sensors attached to a chair and provides a fully-automated TUG test execution. The aTUG consists of a laser range scanner for gait analysis, force sensors in the chair legs to analyze the components of rising from the chair or sitting down and a laser barrier to measure the test duration, which shows a high correlation with stop-watch measurements [ 8 ].…”