Ambulatory estimation of 3D walking trajectory and knee joint angle using MARG Sensors

This paper presents a MARG Sensors based walking motion analysis method that can be used for rehabilitation treatment evaluation under ambulatory conditions in daily lives. A commercial inertial measure unit MTx is fixed on human shank segment. Then digital data box worn on the waist transmits the raw data to laptop with Blue-tooth for post processing. Subjects are required to perform level walking and upstairs walking respectively. After the initial alignment and quaternion convergence, the proposed method fuses the inertial data using Kalman filter based on quaternion. Walking trajectory and knee joint angle are estimated and validated by available ground truth. Experiment results demonstrate that the proposed method has a good performance at both motion patterns. It also shows that no significant drifts exist in the overall results presented in the paper. The method can also be adapted to measure other sites of articulation such as ankle and elbow.