In this paper, we propose an Interactive Digital Signage (IDS) which consists of three parts: passive infrared sensor (PIR), ultrasonic sensors and an embedded system. Our system uses the Newton-Raphson method to acquire the hand moving directions and distances, which were transferred to relative command to control the system. Compared with other interactive devices, we use low cost sensors instead of cameras to approach the audience motion capture. Therefore, the IDS not only supports interaction ability but also decreases hardware and software cost to implement it.