Assessment of Upper Limb Functional Workspace through Inertial Measurement Units: a Pilot Study

The assessment of the upper limb functional workspace in an ecological environment is important for the evaluation of clinical progress in persons suffering from musculoskeletal disorders or neurological impairments. Inertial Measurement Units (IMUs) represent a very effective technology for the assessment of human movement in ecological settings. This work presents a preliminary validation of a methodology for reconstructing and assessing the upper limb functional workspace explored during the daily routine in ecological setting through IMUs. Participants in the study were involved in 7 hours data acquisition with IMUs performing two different protocols simulating an active and a non-active arm, respectively. For each of the two protocols, a workspace for each limb segment and each participant was reconstructed by evaluating the estimated spatial position of the sensors over time. A density and clusterization assessment was performed on each workspace through the application of a Gaussian kernel and k-means algorithm. Next, workspaces from the non-active and the active protocols were compared by performing statistical tests on the distributions of points in the respective workspaces along the the three spatial coordinates. Results showed significant difference between the two protocols (active and non-active) on every spatial coordinate and every of the three segments in the upper limb (arm, forearm, hand) and different clusterization of the workspaces. The findings represent a preliminary confirmation of the applicability of IMUs to the assessment of changes in the functional workspace of the upper limb. Further developments may involve enlarging the sample size, testing on impaired persons, and assessing in more realistic scenarios.