Towards Estimation of Three-Dimensional Knee Rotations

Real-time detection of aberrant knee movements in a competition setting may help reduce the incidence of anterior cruciate ligament knee injuries. We present a hardware design to permit real-time monitoring of knee movement. The proposed device has multiple magnetometer and inertia measurement units, which when combined provide orientation estimates via an extended complementary filter. Knee position is estimated from the sensor orientations and verified against a reference laboratory 3D motion capture system. The proposed method lacks accuracy to resolve quantifiable rotations compared to the reference system; however, the proposed method is useful for free-living, qualitative determination of knee rotations.