10-04-2013, 03:51 PM
Project on Voice Controlled Robot
Voice Controlled.pdf (Size: 1.94 MB / Downloads: 120)
INTRODUCTION
When we say voice control, the first term to be considered is Speech Recognition i.e.
making the system to understand human voice. Speech recognition is a technology where
the system understands the words (not its meaning) given through speech.
Speech is an ideal method for robotic control and communication. The speechrecognition
circuit we will outline, functions independently from the robot’s main
intelligence [central processing unit (CPU)]. This is a good thing because it doesn’t take
any of the robot’s main CPU processing power for word recognition. The CPU must
merely poll the speech circuit’s recognition lines occasionally to check if a command has
been issued to the robot. We can even improve upon this by connecting the recognition
line to one of the robot’s CPU interrupt lines. By doing this, a recognized word would
cause an interrupt, letting the CPU know a recognized word had been spoken. The
advantage of using an interrupt is that polling the circuit’s recognition line occasionally
would no longer be necessary, further reducing any CPU overhead.
Why build robots?
Robots are indispensable in many manufacturing industries. The reason is that the cost
per hour to operate a robot is a fraction of the cost of the human labor needed to perform
the same function. More than this, once programmed, robots repeatedly perform
functions with a high accuracy that surpasses that of the most experienced human
operator. Human operators are, however, far more versatile. Humans can switch job tasks
easily. Robots are built and programmed to be job specific. You wouldn’t be able to
program a welding robot to start counting parts in a bin. Today’s most advanced
industrial robots will soon become “dinosaurs.” Robots are in the infancy stage of their
evolution. As robots evolve, they will become more versatile, emulating the human
capacity and ability to switch job tasks easily. While the personal computer has made an
indelible mark on society, the personal robot hasn’t made an appearance. Obviously
there’s more to a personal robot than a personal computer. Robots require a combination
of elements to be effective: sophistication of intelligence, movement, mobility,
navigation, and purpose.
SPEECH RECOGNITION TYPES AND STYLES
Voice enabled devices basically use the principal of speech recognition.It is the process
of electronically converting a speech waveform (as the realization of a linguistic
expression) into words (as a best-decoded sequence of linguistic units).
Converting a speech waveform into a sequence of words involves several essential steps:
1. A microphone picks up the signal of the speech to be recognized and converts it
into an electrical signal. A modern speech recognition system also requires that
the electrical signal be represented digitally by means of an analog-to-digital
(A/D) conversion process, so that it can be processed with a digital computer or a
microprocessor.
2. This speech signal is then analyzed (in the analysis block) to produce a
representation consisting of salient features of the speech. The most prevalent
feature of speech is derived from its short-time spectrum, measured successively
over short-time windows of length 20–30 milliseconds overlapping at intervals of
10–20 ms. Each short-time spectrum is transformed into a feature vector, and the
temporal sequence of such feature vectors thus forms a speech pattern.
3. The speech pattern is then compared to a store of phoneme patterns or models
through a dynamic programming process in order to generate a hypothesis (or a
number of hypotheses) of the phonemic unit sequence. (A phoneme is a basic unit
of speech and a phoneme model is a succinct representation of the signal that
corresponds to a phoneme, usually embedded in an utterance.) A speech signal
inherently has substantial variations along many dimensions.
DIFFERENCES IN THE VOICES OF DIFFERENT PEOPLE:-
The voice of a man differs from the voice of a woman that again differs from the
voice of a baby. Different speakers have different vocal tracts and source physiology.
Electrically speaking, the difference is in frequency. Women and babies tend to speak at
higher frequencies from that of men.
DIFFERENCES IN THE LOUDNESS OF SPOKEN WORDS:-
No two persons speak with the same loudness. One person will constantly go on
speaking in a loud manner while another person will speak in a light tone. Even if the
same person speaks the same word on two different instants, there is no guarantee that he
will speak the word with the same loudness at the different instants. The problem of
loudness also depends on the distance the microphone is held from the user's mouth.