Multi-gait recognition for a soft ankle exoskeleton with limited sensors

In order to offer appropriate and reliable assistance to users, wearable robotic devices usually detect human locomotion through multi-sensor fusion system. However, multi-sensor fusion system increased the complexity of the sensor system and the burden of wearing on users for ankle exoskeleton. To optimize the sensor system and recognize multi-gait, we present a multi-gait recognition algorithm for a soft ankle exoskeleton with two IMUs (Inertial Measurement Units) mounted on foot. Five gait features are extracted during swing phase, including mean vertical velocity, mean horizontal velocity, vertical displacement, horizontal displacement, and the inclination angle at foot contact. Then, these gait features are used as the input of BPNN (Back Propagation Neural Network) to recognize five common gait modes (level walking, stair ascent/descent, ramp ascent/descent). The proposed algorithm can provide an accurate automatic recognition result at the early beginning of each stance phase. The results of the experiment shown that the proposed algorithm can distinguish above gait modes with 99.0% success rates.