A Compact Harmonic Radar System at 61/122 GHz ISM Band for Physiological Joint Angle Estimation

This paper presents a wearable harmonic radar system for biomechanical joint angle estimation to be used in medical rehab applications. Active frequency doubling reflector tags are placed on a patient's limbs and get detected by a dual receive channel harmonic radar front end. Target-tracking is realized by use of a motion-model based estimator with minimal quadratic error association. Range and angle estimation is performed by bilateration of individual channel target tracks. The resulting positional data is to be used as input for a model-based physiological joint angle estimation, which is not part of this paper. The system is tested on a healthy subject performing gait with multiple strides at a comfortable pace. The positional tracking is compared to equivalent data captured by a marker-based optical motion capturing system, which is the gold standard for gait analysis.