Estimation of knee joint angle during gait cycle using inertial measurement unit sensors: a method of sensor-to-clinical bone calibration on the lower limb skeletal model

Abstract

This study describes a new calibration procedure that provides a simple and accurate method to place and align an inertial measurement unit (IMU) sensor with the relative clinical bone frame on a developed lower limb skeletal model. The calibration can be easily replicated without the need for additional tools and, more importantly, it is independent of the joint attachment position. The proposed method was validated under realistic gait tests using eight healthy subjects in a motion capture system environment. Calculated results showed that the joint angles were correctly measured after applying the calibration method. Therefore, the proposed calibration procedure is an interesting alternative to solve the alignment problem when using IMU sensors for gait analysis.

Keywords

• imu sensor
• static calibration
• tibiofemoral rotation
• clinical bone coordinate system
• skeletal model