In China, the staircases of the school building are crowded, and poor lighting alongside other safety hazards can result in trampling. “Watchmen” is a smart lighting device designed to solve the safety problem of school staircases. There are two different angles of optical design, to ensure the upward and downward stairs are evenly illuminated. The sensor with AI function in the middle can judge the potential safety hazard, warn by voice when at risk and illuminate appropriately. In addition, the “Watchmen” has a simple linear shape and the roller design of the sensor make it easily to adjust the angle.