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Development of an instrumented chair to identify the phases of the sit-to-stand movementInstrumented versions of functional geriatric screening tests have been developed to improve clinical precision. Several different instrumented versions of the Sit-to-Stand (iSTS) test have been developed using a range of sensors such as accelerometers and cameras. An instrumented chair equipped with load cells and an ultrasound sensor was developed to detect phases of the STS (Sit to Stand). The chair was designed to be able to detect all the phases of the STS, including when the person was not in contact with the chair. Performance of the iSTS chair was compared between an RGB camera approach, and a data-fusion approach using the load-cell and ultrasound equipped chair. Ten adult subjects were tested performing the 5STS at two self-selected speeds. The accuracy of the load cell equipped chair was 70%, while the RGB camera achieved 76% accuracy. The ultrasound version of the chair and the fusion of the RGB and load cells technique both achieved significantly better accuracy at 86% and 89%, respectively. The new version of the instrumented chair obtained a high degree of accuracy in detecting the different phases of the STS and is suitable to detect STS phases without requiring additional sensors. Future work will test older subjects and aim to develop new parameters based on the phases of the STS as indicators of physical performance.
A fusion-based approach to identify the phases of the sit-to-stand test in older peopleAutomated clinical tests that assess quality of geriatric screening tests such as the Five-Times-Sit- To-Stand (5STS) and the Timed-Up-and-Go (TUG) are being designed to assess the decline in functional ability of elderly. The existing techniques to assess the quality of these physical activities include sensor-based techniques including body mounted sensors, force sensors and, vision and imaging sensors. These sensors have their own advantages and disadvantages towards the task of clinical assessment. In this work, we introduce a fusion- based technique to combine multiple sensors leveraging advantages of individual sensors, in such a way that the resulting assessment is more accurate. We evaluate our technique for 5STS test using a fusion of a chair and RGB sensors. In a test of 15 older people, there was no significant difference in performance between the two sensors, obtaining 76% and 73% for the RGB and chair, respectively. However, a significant improvement was obtained for the fusion technique, with 90% accuracy for all the phases of the STS test. The proposed fusion technique was observed to be better than the individual sensor assessment.