Non-Line-of-Sight Footstep Localization for Autonomous Mobile Robots

Autonomous mobile robots (AMRs) perform tasks in various industrial applications to enhance productivity and reduce labor costs. To ensure the safety of humans sharing spaces with robots in operation, most AMRs use visual sensors to avoid collision by detecting humans and obstacles. However, when humans are outside the robot's field of vision, the robot should mitigate the risk of collision by sensing humans' presence before they enter the robot's visual range. In this study, we propose a non-line-of-sight sound source localization algorithm that can be applied to collision avoidance for AMRs. The range of human detection for robots can be increased using auditory sensors. To localize the position of a human in a non-line-of-sight area, such as behind a corner of a corridor, we use direction-of-arrival (DOA) estimation of reflection sounds and the ray tracing method. Performance evaluations in real life were performed to verify the possibility of its implementation in practical scenes.