Weight surfaces

The Weight surfaces are surfaces (such as a table or a floor) that are equipped with four load cells to sense the weight and weight distribution on the surface. Using the data of each of the four load cells, one can determine where a weight is placed on the table. Each time that an object is added or removed its posistion can be recorded.

Load sensing is a mature and robust technology widely applied in process control. In developing weight surfaces we consider the use of load sensing in everyday environments as an approach to acquisition of contextual information in ubiquitous computing applications. Since weight is an intrinsic property of all physical objects, load sensing is an intriguing concept on the physical-virtual boundary, enabling the inclusive use of arbitrary objects in ubiquitous applications. We have found that load sensing is a versatile source of contextual information.

Through a series of experiments we have found that using load sensing techniques we can obtain not just weight information, but object position and interaction events on a given surface. Weight surfaces can be used for a range of purposes. These might include:

1. Someone sits at a weight table and puts a glass on the table. She picks up a book that was already on the table. After a while she is drinking from the glass and puts it back on the table. These actions are recognized by the table.
2. A weight table is used as pointing device for a home entertainment system. By moving one or several fingers or an object on the surface of the table the position of the mouse pointer is manipulated.
3. A weight floor can monitor where furniture is. For example, it can detect where people are in the room, and adjust the surround sound system accordingly.

The hardware consist of a Smart-it used as base station, one Smart-It with an load AddOn Board as sensor. The general layout is shown below: