An Experiment on the Description of Sequences of Fuzzy Perceptions

The idea of linguistic variable in fuzzy logic allows the representation of the subjective meaning of a measure at a given instant of time. This paper explores possibilities of extending the concept of linguistic term to create the linguistic description of the temporal evolution of a signal. We focus our effort in signals that, having potentially an infinite duration, present more or less repetitive patterns. We introduce the concept of fuzzy alphabet as an extension of the concept of alphabet in automata theory. The fuzzification of the sequence of sampled inputs is used to create an initial description of the signal. Then we use a fuzzy finite state machine transducer to create a linguistic description of the signal temporal evolution made with concepts of a higher level of abstraction. A simple experiment monitoring the accelerations produced while driving an automobile has delivered promising results: we have automatically generated a linguistic report describing the perceptions obtained in the car caused by the physical characteristics of the road traveled and the driver´s style of driving.