There are a number of systems and devices for spacial measurement which can be used to measure bodily motion. However, these systems are usually large or fixed with the environment. In this study, we propose a novel modular device that allows users to create geometric shapes in the real world and also a flexible sensing space within the created shape. Users can freely put devices and rotate them so that a geometrical shape could appear on the floor. As the modular devices and the emitted laser beam represent the corners and sides of the shape, respectively, the device therefore does not interrupt figures or textures on the ground. The developed system provides an interactive visual/audio environment as if children could make a hand drawing on the ground or floor and play with the created shapes.

Each module emits both single laser beam and infrared beam to the same direction by receiving an infrared beam from the other module. Therefore, the relative angle between incoming and outgoing laser beams can be calculated at each module. Once an enclosed region is created, the modules automatically detect the created shape and start to measure in the region. The modules communicate with each other so as to detect comings and goings in the region by using position detection sensors installed in each module. Polygonal shapes such as rectangle and pentagon, and different shape like star can be created solely by changing the locations of modules.

We have conducted several experiments by using the developed modules. For example, we used more than two groups of modules (AirTiles) and designed a simple game for motion guidance. We asked users to create two AirTile on the desktop and then LEDs of one AirTile start to blink on and off. When the user put his hand in the AirTile, another AirTile starts to blink. On the other hand, these modules can be used as a bodily exercise tool. Side stepping is a simple exercise that the user should shift back and forth between predetermined two regions. In this case, the user first create two regions by AirTile and simply do the exercise. As AirTiles can be used as the data logger, exercise quantity and timing of footwork are recorded and analyzed after the exercise. Other potential applications include the human-behavior measurement, motion guidance, and therapeutic exercise.