Validation of Attitude and Heading Reference System and Microsoft Kinect for Continuous Measurement of Cervical Range of Motion Compared to the Optical Motion Capture System

Abstract

ObjectiveTo compare optical motion capture system (MoCap), attitude and heading reference system (AHRS) sensor, and Microsoft Kinect for the continuous measurement of cervical range of motion (ROM).MethodsFifteen healthy adult subjects were asked to sit in front of the Kinect camera with optical markers and AHRS sensors attached to the body in a room equipped with optical motion capture camera. Subjects were instructed to independently perform axial rotation followed by flexion/extension and lateral bending. Each movement was repeated 5 times while being measured simultaneously with 3 devices. Using the MoCap system as the gold standard, the validity of AHRS and Kinect for measurement of cervical ROM was assessed by calculating correlation coefficient and Bland–Altman plot with 95% limits of agreement (LoA).ResultsMoCap and ARHS showed fair agreement (95% LoA<10°), while MoCap and Kinect showed less favorable agreement (95% LoA>10°) for measuring ROM in all directions. Intraclass correlation coefficient (ICC) values between MoCap and AHRS in –40° to 40° range were excellent for flexion/extension and lateral bending (ICC>0.9). ICC values were also fair for axial rotation (ICC>0.8). ICC values between MoCap and Kinect system in –40° to 40° range were fair for all motions.ConclusionOur study showed feasibility of using AHRS to measure cervical ROM during continuous motion with an acceptable range of error. AHRS and Kinect system can also be used for continuous monitoring of flexion/extension and lateral bending in ordinary range.

Concurrent validity and reliability of the Microsoft kinect™ device in cervical spine range of motion assessment

“…This finding is in agreement with the study by Young et al [30], who investigated the validity of the Microsoft Kinect™ in the assessment of continuous cervical motion. They compared the values of cervical spine measurements of the Kinect system and the optical motion capture system (MoCap).…”

“…Furthermore, it should be pointed out that the Kinect has higher measurement errors in rotation angle measurements [33] in comparison with other cervical motions. Young et al [30] have found as high as 14.25⁰ measurement errors in axial rotation by the Kinect and this may be responsible for its lower correlation compared to other cervical motions as observed in our and other studies..…”

“…They have reported a less favorable agreement between the MoCap and the Kinect (95% LoA>10⁰) in the assessment of continuous cervical ROM in all directions. According to their findings, the Kinect showed larger measurement errors compared with MoCap in monitoring cervical continuous motion [30].…”

“…The Kinect accuracy can be affected by the distance between subjects and the recognition precision [30]. According to the Kinect sensor user manual, the best field of view for the Kinect is obtained when the sensor is located at a distance of 0.8-2.5 m (for seated mode) from participants, although the maximum and minimum range for the Kinect for tracking is between 0.8-6.5m [34].…”

“…Instead, it is rather complex and dynamic [37]. A multi-joint model rather than a single-joint model is needed to describe the cervical spine [30].…”