Comparative Evaluation of Commercial and Custom-Designed Inertial Systems for Physical Activity Analysis

Inertial measurement units (IMUs) are now widely used to provide medical staff with objective data on patients’ physical activity. The data collected by these devices allow for the monitoring of individuals’ physical activity, either for the purpose of disease prevention or rehabilitation. This data may be gathered either through short-term testing or by tracking activities over several days to gain insights into activities of daily living (ADLs). It is of utmost importance to select IMUs that meet specific criteria. In many cases, the optimal choice is a mid-to-high-end device that is user-friendly but often costly. This paper compares the commercial high-cost NGIMU multisensor device with two other low-cost “chip-level” IMUs that require additional hardware to obtain the necessary information. The objective is to assess whether these low-cost devices provide sufficiently accurate information for measuring physical activity in patients. To this end, raw accelerometer and gyroscope data are extracted from each IMU, which will be the inputs to a set of algorithms to obtain features and output data associated with physical activity after testing in controlled environments.