Real-Time Animator and Requirements Traceability - Using Event-B for Critical Device Software Systems - page 86

Fig. 5.2 A prototype model of the functional architecture to animate a formal specification

5.5.1 Data Acquisition & Preprocessing

Data acquisition and preprocessing begin with the physical phenomenon or physi-
cal property to be measured. Examples of this include temperature, light intensity,
heart activities and blood pressure [ 15 ] and so on. Data acquisition is the process of
sampling of real-world physical conditions and conversion of the resulting samples
into digital numeric values. The data-acquisition hardware can vary from environ-
ment to environment (i.e. camera, sensor, etc.). The components of data-acquisition
systems include sensors that convert physical properties. A sensor, which is a type
of transducer, that measures a physical quantity and converts it into a signal which
can be read by an observer or by an instrument.
Data preprocessing is a next step to perform on the raw data to prepare it for
another processing procedure. Data preprocessing transforms the data into a format
that will be more easily and effectively processed for the purpose of the user. There
are a number of different tools and methods used for preprocessing on different
types of raw data, including: sampling, which selects a representative subset from
a large population of data; transformation, which manipulates raw data to produce
a single input; de-noising, which removes noise from data; normalisation, which
organises data for more efficient access.

5.5.2 Feature Extraction

The features extraction unit is a set of algorithms that is used to extract the param-
eters or features from the collected data set. A set of algorithms is implemented in
any particular language (Matlab, C, C++, etc.). All these algorithms are different
for each system. For example, during prototype implementation of this architecture,
we have used a set of algorithms for extracting the ECG features or parameters.
These parameters or features are numerical values that are used by animated model
at the time of animation. The feature extraction relies on a thorough understanding