A Prototype System to Measure the Trunk Angle in Sagital Plane

Mohammad I. Mokhlespour, Masoud Ramezanzadeh, Roya Narimani, and Ali Soroush


Trunk measuring system, Rubbery ruler sensor, Flexion, Extension


The most prevalent musculoskeletal condition and one of the most disabilities are caused by low back pain. In the low back pain, a large variety of evaluation tools is presented to assess the results of the treatment; therefore, it is important to measure the trunk angle in order to determine the progress during patient’s treatment. In this project, we developed a low cost prototype system for flexion-extension movement to measure the angle of the trunk in sagital plane. The system consists of clothing that is stretchable; a Rubbery Ruler sensor (RRs) attached on clothing, data acquisition system. Inertial Magnetic Unit (IMU) sensor installed on spine is used to calibrate the orientation for the output of RRs twenty times. This system was validated by repeated experiments. The curve equation of the RRs output versus the IMU output is presented. Finally, this curve equation can be used to determine the angle of trunk in the clinical applications.

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