Lower limb motion tracking using IMU sensor network

A motion capture system was constructed with 7- Inertial Measurement Units (IMU) covering the lower limb segments, with a wireless connection to a PC for data logging. IMU units were used to measure the lower limb segment's angular velocity and linear acceleration as direct biomechanical variables. Meanwhile, Lower Limb joints and segments inclination, in the sagittal plane, were calculated indirectly, using IMUs' direct outputs. The outputs undergo several signal conditioning phases to remove noises and bias. Furthermore, misalignment effect on the raw data is removed by an on-body calibration of the sensors. Finally, for activity recognition purposes, T-test is used to prove that capturing motion along only one side of the lower limb is sufficient, due to redundancy in the corresponding features of the biomechanical signals (variables) of each leg.