Smart Table

Objects

Objects require a label towards the table surface in order to be tracked and identified by Smart Table. The label is necessary for position localization and orientation as well as identifying objects where objects' shapes themselves may not differ much from each other.

The picture below presents one possible pattern for a label. The distance between two pads is denoted by P. Length and width of an object is labeled with L. Magnets are placed at five different positions on the back of an object, which allows the encoding of a binary number. The size of a magnet is chosen such that it covers one hall effect sensor. Placing a magnet on top of a sensor activates only this particular sensor and the presence of a magnet can be read by the microcontroller.

The number of magnets is kept constant utilizing a special coding scheme for the binary number. Instead of using the presence or absence of a magnet to code logic one or zero this information is implied in the position of a magnet. As can be seen from the right hand side of the picture below, a magnet (light blue) is either placed in the upper half of an imaginary rectangle representing a logic one or in the lower half for a logic zero.

The following photo shows the back of a wooden object. In that particular example, the positions of five magnets encode the number 'zero'.

This material is based upon work supported by the National Science Foundation under Grant No. ANI-0085773. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation (NSF).