A study of gait analysis with a smartphone for measurement of hip joint angle

Due to the enhanced performance of recent smart-phones, some studies use them for gait analysis. An accelerometer in a smartphone can be used to measure gait parameters such as steps and walking speed. Some researchers proposed methods of measuring these parameters with a smartphone, but they did not propose methods of measuring joint angles, which are typical parameters for gait analysis. In this paper we propose a method to measure hip joint angle with a smartphone by putting it in a front trouser pocket. We conducted an experiment to verify the accuracy of the proposed method. We compared the measured hip joint angle with a 3D system and a smartphone. The results showed that the coefficients of determination were about 0.7-0.9 and the root mean square error was about 4-6 degrees.