Ambulatory monitoring of physical activity based on knee flexion/extension measured by inductive sensor technology

We developed a knee brace to measure the knee angle and implicitly the flexion/extension (f/e) of the knee joint during daily activities. The goal of this study is to classify and validate a limited set of physical activities on ten young healthy subjects based on knee f/e. Physical activities included in this study are walking, ascending and descending of stairs, and fast locomotion (such as jogging, running, and sprinting) at self-selected speeds. The knee brace includes 2 accelerometers for static measurements and calibration and an inductive sensor for dynamic measurements.Aswe focus on physical activities, the inductive sensorwill provide the required information on knee f/e. In this study, the subjects traversed a predefined track which consisted of indoor paths, outdoor paths, and obstacles. The activity classification algorithm based on peak detection in the knee f/e angle resulted in a detection rate of 95.9% for walking, 90.3% for ascending stairs, 78.3% for descending stairs, and 82.2% for fast locomotion.We conclude that we developed a measurement device which allows long-termand ambulatorymonitoring. Furthermore, it is possible to predict the aforementioned activities with an acceptable performance.

Publication year:2013

Accessibility:Open