CovertEye: Gait-Based Human Identification under Weakly Constrained Trajectory

As a non-intrusive sensing approach, the gait-based human identification technique attracts extensive attention. For the gait-based human identification technique, the unique gait feature is captured and extracted. Owing to the strong environment robustness and good privacy protection, the radar, especially the single-input multiple-output (SIMO) Doppler radar, is proposed as a promising way to capture the gait feature. However, the existing SIMO Doppler radar-based methods require the person to walk along a straight-line trajectory, which hinders their practical application. In this paper, we propose a gait-based human identification system for the weakly constrained trajectory, called CovertEye. In CovertEye, the person can be identified, when he/she walks along variable directions. To this end, we propose a trajectory segmentation algorithm to divide the trajectory into many straight-line trajectory segments. Based on the trajectory segments, we design the gait-based human identification method. In particular, we propose a normalization method to eliminate the differences in the direction of movement and the length among trajectory segments. The normalized signal spectrogram is exploited for the deep learning based feature extraction and human identification. We develop a prototype of the CovertEye system. The extensive experimental results demonstrate that our proposed system can achieve the identification accuracy of 82.4%.