An Evaluation of an Electronic System for the Continuous and Simultaneous Assessment of Body Postures

This paper describes the initial evaluation of an electronic system that makes use of accelerometers that act as electronic inclinometers during static or semi-static (constant angular velocity) conditions and estimates angles with respect to gravity within 2 to 3 degrees. The accelerometers are attached directly to the body near the joint of interest and have been used to estimate shoulder, knee and trunk flexion. A study was conducted to evaluate the accuracy of the electronic inclinometer system to evaluate body postures. Measurements were made with a manual goniometer or weighted inclinometer and the electronic inclinometers simultaneously as 5 subjects who wore the device assumed a variety of different static postures. Several calibration procedures for each body region, ranging from no calibration for the individual to relatively involved calibration procedures, were used in the evaluation. The electronic inclinometers predicted shoulder, knee and trunk flexion to within about 5 to 10 degrees of the manual instruments with no or relatively simple calibration procedures. These preliminary results suggest that the electronic system may be useful for nearly continuous and simultaneous postural evaluation of multiple body parts with relatively little interference to working postures, at least for relatively static body postures.