Physical sensor difference-based method and virtual sensor difference-based method for visual and quantitative estimation of lower limb 3D gait posture using accelerometers and magnetometers

Abstract

An approach using a physical sensor difference-based algorithm and a virtual sensor difference-based algorithm to visually and quantitatively confirm lower limb posture was proposed. Three accelerometers and two MAG³s (inertial sensor module) were used to measure the accelerations and magnetic field data for the calculation of flexion/extension (FE) and abduction/adduction (AA) angles of hip joint and FE, AA and internal/external rotation (IE) angles of knee joint; then, the trajectories of knee and ankle joints were obtained with the joint angles and segment lengths. There was no integration of acceleration or angular velocity for the joint rotations and positions, which is an improvement on the previous method in recent literature. Compared with the camera motion capture system, the correlation coefficients in five trials were above 0.91 and 0.92 for the hip FE and AA, respectively, and higher than 0.94, 0.93 and 0.93 for the knee joint FE, AA and IE, respectively.

Keywords:

• gait posture analysis
• accelerometer
• magnetometers
• virtual sensor

Acknowledgements

The authors wish to acknowledge the support of the volunteer subjects of Robotics and Dynamics Research Lab in Kochi University of Technology.

Notes

¹During the production process, Liu Kun's affiliation has changed to College of Mechanical Science and Engineering, Jilin University, Nanling Campus, Changchun China, 130000.

Additional information

Notes on contributors

Kun Liu

1