Evaluation of Upper Body and Lower Limbs Kinematics through an IMU-Based Medical System: A Comparative Study with the Optoelectronic System

Abstract

In recent years, the use of inertial-based systems has been applied to remote rehabilitation, opening new perspectives for outpatient assessment. In this study, we assessed the accuracy and the concurrent validity of the angular measurements provided by an inertial-based device for rehabilitation with respect to the state-of-the-art system for motion tracking. Data were simultaneously collected with the two systems across a set of exercises for trunk and lower limbs, performed by 21 healthy participants. Additionally, the sensitivity of the inertial measurement unit (IMU)-based system to its malpositioning was assessed. Root mean square error (RMSE) was used to explore the differences in the outputs of the two systems in terms of range of motion (ROM), and their agreement was assessed via Pearson’s correlation coefficient (PCC) and Lin’s concordance correlation coefficient (CCC). The results showed that the IMU-based system was able to assess upper-body and lower-limb kinematics with a mean error in general lower than 5° and that its measurements were moderately biased by its mispositioning. Although the system does not seem to be suitable for analysis requiring a high level of detail, the findings of this study support the application of the device in rehabilitation programs in unsupervised settings, providing reliable data to remotely monitor the progress of the rehabilitation pathway and change in patient’s motor function.

SensAA—Design and Verification of a Cloud-Based Wearable Biomechanical Data Acquisition System

“…SensAA achieved an RMSE of 2.9° to 8° for walking speeds between 3 and 12 km/h. The results of walking at 3 km/h deviated less than those of most previous studies, which reported RMSE values between 3.2° and 5.9° [ 25 , 26 , 27 , 28 , 33 , 34 , 37 , 41 ]. These studies describe the walking activity during their measurement routine only as walking and do not give an exact speed.…”

“…Wearable systems based on inertial measurement units (IMUs) have been recently a subject of extensive research [ 12 , 14 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 ]. These systems, while not yet delivering the same accuracy as optical systems, can be operated everywhere and not only in a stationary environment equipped with cameras.…”

“…However, to our knowledge, no device has yet been described that combines all desired goals. These approaches lack at least one of the following aspects: Low-cost solution [ 28 , 36 , 37 , 40 ] Easy setup and low calibration effort [ 25 , 27 , 28 ] Compact and wireless design [ 14 , 34 , 46 ] Continuous and secure data upload to cloud server [ 26 , 28 , 34 , 36 , 37 , 40 , 46 , 47 , 48 ] Data upload outdoors without WIFI connection [ 28 , 36 ] Energy optimization for long-term measurements [ 28 , 36 , 37 , 40 ] Secure data transfer for multiple users [ 26 , 34 , 37 , 40 , 46 , 47 , 48 ] …”

Characterization of Upper Extremity Kinematics Using Virtual Reality Movement Tasks and Wearable IMU Technology

“…Particularly for upper extremity (UE) movement, more quantitative kinematic assessments could be especially useful, as they have been less studied than qualitative, visual, and spatiotemporal metrics [ 17 ]. Advances in inertial measurement unit (IMU) sensors and their associated systems have been shown to provide high-quality quantitative data at a lower cost than other conventional methods, including camera-based motion capture [ 17 , 18 , 19 , 20 , 21 , 22 ]. Prior works have demonstrated the feasibility of using IMU systems to assess the clinic or home activity of the UE.…”

“…For example, a small chronic stroke cohort demonstrated the feasibility of using the Xsens IMU system to quantify UE workspace, number of reaches, and joint kinematics at time points over several months [ 23 ]. As biosensors improve in capability, ease of use, portability, and cost, they become increasingly feasible for adoption and integration beyond research labs to therapeutic and clinical use [ 19 , 20 , 21 , 22 , 23 ]. However, data from these IMU systems would be more comparable and useful if also collected during specific, known UE tasks in addition to general activities of daily living.…”