Body-fixed Orientation Sensors for Trunk Motion Sensing

Abstract

Awkward trunk postures and dynamic trunk movements are associated with increased risk of low back disorders (LBDs). Recent advancements in computing and micro-electromechanical systems (MEMS) technology have resulted in high precision, compact, and relatively inexpensive commercial orientation sensors that address the workplace usage limitations of the most common kinematics measurement methods (video analysis, magnetic field sensors, and electrogoniometers). The purpose of this study is to review the available body-fixed orientation sensing technology for its use in ergonomics research and practice. A laboratory study of a custom MEMS accelerometer-based inclinometer highlights issues of axial orientation, vibration, and non-gravitational acceleration that affect orientation results from basic inclinometers. Techniques are presented for correcting for such issues in advanced sensors using computational methods and combinations of MEMS accelerometers, gyroscopes, and/or magnetometers. Body-fixed orientation sensors provide enhanced opportunities to identify and reduce harmful work postures that may reduce the prevalence and severity of work-related musculoskeletal disorders (WMSDs).