Validation and Assessment of a Posture Measurement System with Magneto-Inertial Measurement Units

Abstract

Inappropriate posture and the presence of spinal disorders require specific monitoring systems. In clinical settings, posture evaluation is commonly performed with visual observation, electrogoniometers or motion capture systems (MoCaps). Developing a measurement system that can be easily used also in non-structured environments would be highly beneficial for accurate posture monitoring. This work proposes a system based on three magneto-inertial measurement units (MIMU), placed on the backs of seventeen volunteers on the T3, T12 and S1 vertebrae. The reference system used for validation is a stereophotogrammetric motion capture system. The volunteers performed forward bending and sit-to-stand tests. The measured variables for identifying the posture were the kyphosis and the lordosis angles, as well as the range of movement (ROM) of the body segments. The comparison between MIMU and MoCap provided a maximum RMSE of 5.6° for the kyphosis and the lordosis angles. The average lumbo-pelvic contribution during forward bending (41.8 ± 8.6%) and the average lumbar ROM during sit-to-stand (31.8 ± 9.8° for sitting down, 29.6 ± 7.6° for standing up) obtained with the MIMU system agree with the literature. In conclusion, the MIMU system, which is wearable, inexpensive and easy to set up in non-structured environments, has been demonstrated to be effective in posture evaluation.

Wearables for Monitoring and Postural Feedback in the Work Context: A Scoping Review

“…Inertial measurement unit (IMU) is the common underlying technology for most wearables [ 7 , 21 , 22 ]. It is possible to identify static and dynamic improper postures that are maintained for long periods [ 23 , 24 ] through discrete and continuous monitoring of body posture in real-world settings [ 21 , 25 ] in a shorter timeframe/in a shorter time [ 5 ].…”

“…Inertial measurement unit (IMU) is the common underlying technology for most wearables [ 7 , 21 , 22 ]. It is possible to identify static and dynamic improper postures that are maintained for long periods [ 23 , 24 ] through discrete and continuous monitoring of body posture in real-world settings [ 21 , 25 ] in a shorter timeframe/in a shorter time [ 5 ]. Other advantages of wearables that make them robust for integration in monitoring work activity include objective, reliable, and accurate results [ 26 ] which provide a trustworthy and realistic assessment of work-related conditions [ 27 ]; low cost; lightweight design; small size; portability; and energy efficiency [ 28 ].…”

Postural Evaluation in Young Healthy Adults through a Digital and Reproducible Method

“…However, this system has a high cost, and it is difficult to implement in postural screening for the general population. Other valid tools such as inertial measurement units (e.g., accelerometers, magneto inertial units) are also employed in the field of postural evaluation for the assessment of the thoracic kyphosis and the lumbar lordosis angles [ 9 ] and also for gait and balance assessment [ 10 ].…”

Development of an Automatic Air-Driven 3D-Printed Spinal Posture Corrector

“…In [19], the author proposed a posture assessment system based on three magnetoinertial measurement units (MIMU), which later compared with motion capture systems (MoCaps). MIMUs are placed on thoracic vertebra (T3, T12) and sacral vertebra (S1).…”