A robot 20 periodically moves along specified routes in a user's living
space 1, collecting the ID data items of objects 40 existing in the
living space 1. Each object 40 has a radio tag 10, which stores the ID
data of the object 40. The robot 20 has a communications unit 26. While
the robot 20 is moving, the unit 26 keeps transmitting an electric wave
to which the radio tags 10 can respond. Upon receiving the electric wave,
each radio tag 10 transmits the ID data of the object 40. The robot 20
receives the ID data and generates property data by adding, to the ID
data, the data representing the time and position at which the radio tag
10 has transmitted the ID data. The property data shows what exists where
and when. A data-managing apparatus 30 has a meta-data recording unit 31,
which converts the property data to meta data. The meta data can be used
in various types of data-processing apparatuses.
