MotionBeep: Enabling Fitness Game for Collocated Players With Acoustic-Enabled IoT Devices

Fitness games recently attract much attention these years due to its combination of playability and athleticism. However, most fitness games are entertainment for a single person, with only a few deliver distinctive experiences for multiplayers. Enabling interaction between multiple players would be more enjoyable due to exciting cooperation among players. Considering a Big Stomach Challenge for two players, a certain amount of food can be only eaten when a mouth size, represented by the distance between players is reached collaboratively. Similarly, a certain type of food can only be picked up when the food grabbing speed, denoted by the approaching speed between players, is fast enough. Such games require accurate ranging and speed estimation in a relatively long distance (1–15 m) to deliver a good gaming experience. However, existing ranging schemes cannot meet the above requirements. They either cannot work under Doppler channels or have to strike a balance between accuracy and operational range, prohibiting a heuristic implementation for the above games. To this end, we design MotionBeep, a novel acoustic ranging scheme that achieves centimeter-level ranging and dm/s-level speed estimation accuracy under representative indoor and outdoor scenes within 15 m. In MotionBeep, we design a new working paradigm and incorporates a state-space model to maintain accurate ranging in both static and dynamic channels. We have implemented a system prototype and evaluate its performance in representative environments. Evaluation results demonstrate that MotionBeep achieves a median of centimeter accuracy with up to 15 m even under Doppler effect.