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Kinematics of Gait: New Method for Angle Estimation Based on Accelerometers
School of Electrical Engineering, University of Belgrade, Bulevar kralja Aleksandra 73, Belgrade, Serbia
Tecnalia Serbia, Vladetina 13/6, Belgrade, Serbia
Center for Sensory Motor Interaction, Aalborg University, Fredrik Bajers Vej 7, Aalborg, Denmark
* Author to whom correspondence should be addressed.
Received: 1 October 2011; in revised form: 24 October 2011 / Accepted: 25 October 2011 / Published: 7 November 2011
Abstract: A new method for estimation of angles of leg segments and joints, which uses accelerometer arrays attached to body segments, is described. An array consists of two accelerometers mounted on a rigid rod. The absolute angle of each body segment was determined by band pass filtering of the differences between signals from parallel axes from two accelerometers mounted on the same rod. Joint angles were evaluated by subtracting absolute angles of the neighboring segments. This method eliminates the need for double integration as well as the drift typical for double integration. The efficiency of the algorithm is illustrated by experimental results involving healthy subjects who walked on a treadmill at various speeds, ranging between 0.15 m/s and 2.0 m/s. The validation was performed by comparing the estimated joint angles with the joint angles measured with flexible goniometers. The discrepancies were assessed by the differences between the two sets of data (obtained to be below 6 degrees) and by the Pearson correlation coefficient (greater than 0.97 for the knee angle and greater than 0.85 for the ankle angle).
Keywords: accelerometers; ambulatory system; angles; gait assessment
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Djurić-Jovičić, M.D.; Jovičić, N.S.; Popović, D.B. Kinematics of Gait: New Method for Angle Estimation Based on Accelerometers. Sensors 2011, 11, 10571-10585.
Djurić-Jovičić MD, Jovičić NS, Popović DB. Kinematics of Gait: New Method for Angle Estimation Based on Accelerometers. Sensors. 2011; 11(11):10571-10585.
Djurić-Jovičić, Milica D.; Jovičić, Nenad S.; Popović, Dejan B. 2011. "Kinematics of Gait: New Method for Angle Estimation Based on Accelerometers." Sensors 11, no. 11: 10571-10585.