Electronic Nose Based Beverage Identification by an Improved Fisher Discriminate
Analysis Method
Tao Liu, Lei Zhang, Yanbin Chen, Dongqi Li, Mengya Wu and Xingrui Cui
College of Communication Engineering, Chongqing University, Chongqing 400044, China
cquliutao@cqu.edu.cn; leizhang@cqu.edu.cn
Abstract—Electronic noses are widely employed in food
industry and play an important role in beverage
identifications. Meanwhile, fisher discriminate analysis is
considered as one of convenient pattern recognition
methodologies for electronic noses. Traditional fisher
discriminate analysis (FDA) is a kind of binary classifiers. In
other words, it is not competent to multi-class classifications
which are common in daily concerns. To solve the limitation of
the binary classifier, we presented a FDA based classification
method, namely encoding fisher discriminate analysis (EFDA),
which can be applied to multi-class recognition. In this paper,
seven kinds of beverages including Chinese liquor, beer, wine,
green tea, black tea, oolong tea and pu’er tea were prepared
and tested objectively by an electronic nose (E-nose) system
with 32 gas sensors. The E-nose system was a prototype for
general detection of complicated gaseous compounds . It
performed all the experiments and tested the volatile
compounds of seven beverages. The experimental results
indicated that the proposed method were more effective than
conventional pattern recognition methods such as principal
component analysis (PCA) and k-nearest neighbor (k-NN).
The highest recognition rate could reach 96.83% by EFDA.
The outcomes achieved demonstrated that EFDA can be
successfully used in multi-class identifications.
Keywords—electronic nose; fisher discriminate analysis;
beverage; binary encoding
I. I
NTRODUCTION
Artificial olfactory sensation is a novel technology to
simulate human-smell process to indentify various gaseous
compounds. Typically, when a gas sensor array associates
with pattern recognition models, an artificial olfactory
system is composed. This kind of machine, namely
electronic nose (E-nose), has great potential in complicated-
ingredient-gas sensing for their evident superiorities such as
high speed, good reproducibility and non-invasion.[1] On
the other hand, food safety and quality become more and
more important in modern society due to increasing concern
on human health and living quality. Thus, instead of
traditional chemical instruments, E-noses supply a
convenient way to perform special detections of food
industry in which beverage discriminations usually play an
important role. [2]
Communities have made quite a few efforts to the
scientific researches about beverage identifications. Among
them, some scholars pay attention to distinguish various
categories of tea according to types, grades, even habitats
with commercial E-nose systems.[3]-[5] Meanwhile, some
studies focus on differentiating kinds of alcoholic drinks on
their different aromatic flavors.[6][7] Furthermore, positive
attempts have been performed to show strong ability of
olfactory machines to recognize different fruit juices and
milks. [8]-[10] Generally speaking, suited pattern
recognition models are needed to infer certain results from
sensor-array responses in E-nose machines. As far as it is
concerned, a few methods such as principal component
analysis (PCA), fisher discriminate analysis (FDA), k-
nearest neighbor algorithm (k-NN) and artificial neural
network (ANN) have been adopted for E-nose based
beverage tests and shown obvious
validity and practicability in the reports aforementioned.
Although FDA with the advantages of simple and easy
realization is frequently used in pattern recognition of E-
nose systems, conventional FDA method only fits for a
binary classification.[11]-[13] That is to say that FDA is
only a binary classifier. In order to extend the applied range
of FDA to multi-class identifications, either one-against-
one or one-against-all strategies[14][15] has been
considered to be a suitable scheme instead of the traditional
one. However multi-class identification of FDA, even other
binary classifiers, is so far an interesting issue for the need
of convenient recognition solutions. The wide applications
and issues of E-nose can be referred to as [16]-[18].
In this paper, the authors proposed a novel multi-type
classification strategy, called Encoding FDA (EFDA),
which combined binary encoding and hamming-distance
measurement with FDA to explore a better FDA based
multi-class classifier. Meanwhile, we also designed and
developed an E-nose platform with 32 gas sensors for gas
tests. Seven types of beverages including Chinese liquor,
beer, wine, green tea, black tea, oolong tea and pu’er tea
were prepared as testing samples. Then EFDA, k-NN and
PCA were adopted as pattern recognition part of E-nose.
Comparison of the three method was presented and the
recognition accuracy of EFDA was the best one among
three adopted methods. It hinted that EFDA had favorable
prospects in multi-class applications. The rest of this paper
is organized as follows: In Section II, we illustrate the
hardware architecture of the proposed E-Nose platform and
describe the principle of the methods used in algorithm
validation. Then the experimental setup, results and
2016 Asia Multi Conference on Modelling and Simulation
2376-1172/16 $31.00 © 2016 IEEE
DOI 10.1109/AMC.2016.20
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