Designing a Voice Activated Compartmentalized Safe with Speech Processing using Matlab Preliminary Design Review

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Designing a Voice Activated Compartmentalized
Safe with Speech Processing using Matlab
Preliminary Design Review

• Amy Anderson
• Ernest Bryant
• Mike Joyner
• Collins Pratt
• October 19, 2007
• Georgia Institute of Technology
• ECE 4007 Senior Design

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Project Overview

• Design a voice activated, motor driven,
  compartmentalized safe using computer, Matlab
  software and microcontroller
• Intend for residential and commercial use
  specifically homeowners and small business owners
• Estimate costs for retail unit at 1200

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Design Objectives

• Build a wooden cylindrical compartmentalized safe
  prototype
• Allow access to each compartment through
  specific, user programmed voice password
• Develop Matlab program capable of identifying and
  verifying two specific speakers
• Develop GUI to allow user to easily configure and
  operate safe
• Interface computer and microcontroller through
  Matlab and serial cable
• Use microcontroller to control stepper motor that
  rotates safe top

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Block Diagram of Safe Prototype
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Safe Prototype Design

• Dimensions 18 diameter x 6 height
• Base constructed of ¾ plywood
• Compartment interior walls constructed of ¼
  plywood
• Side walls constructed of 1/16 door skin plywood
• Top constructed of ¼ plexi-glass for
  demonstration purposes
• Slot routed out for motor
• Center PVC designed to house motor shaft
• Motor and microcontroller contained inside
  blanked off, spare compartment

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1.8o, 24V Unipolar Stepper Motor

• Rotates top of safe clockwise and
  counterclockwise to allow access to all
  compartments
• Receives a predetermined sequence of applied
  currents to the stator windings from the
  microcontroller
• For Clockwise Rotation
• Winding 1a 1100110011001100110011001
• Winding 1b 0011001100110011001100110
• Winding 2a 0110011001100110011001100
• Winding 2b 1001100110011001100110011
• 0 de-energized, 1 energized
• For Counterclockwise Rotation reverse sequence

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1.8o, 24V Unipolar Stepper Motor

• The animation illustrates the rotor turning
  proportionally to the sequence of applied
  currents to the stator windings

Animation borrowed from http//www.cs.uiowa.edu/j
ones/step/typesf/2anim.html
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PIC18F452 Microcontroller

• Protected from back feed of high motor voltage by
  Darlington transistor (UL2003) array
• Controls motor rotation by energizing wires
  through Port B of the PIC
• Determines how much to rotate motor based on data
  received from Matlab program through 9 pin serial
  cable

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Serial Port Communications

• Serial Port connects computer with the PIC
• Matlab sends specified speaker number through
  port to PIC
• Serial port transmits 8 bits one bit at a time
  need program to recognize when full 8 bits
  received

RS232 9-pin serial port
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Serial Port Program

• Written in assembly language
• Written to recognize when 8 bits are sent
• Checks to see when full word (8 bits) is received
  by checking a bit within the register that turns
  on high when the full word is received by the
  microcontroller
• When full word is received, the PIC turns the
  motor according to specified word received

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Matlab Overview

• Receives speech data (1 password per compartment)
  through microphone for initial configuration
• Extracts features of received speech to create
  model for later comparison
• Receives input speech to be verified
• Compares input speech to stored model for each
  compartment
• Verifies speech and password and sends 8 bit word
  to microcontroller through serial port to access
  the specified users compartment

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Matlab Speech Algorithms

• Used two main algorithms for speech processing
• For feature extraction Mel Frequency Cepstral
  Coefficients
• For speaker modeling and classification Vector
  Quantization Code Book

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Mel Frequency Cepstral Coefficients
Extracts cepstral coefficients

• Representation of a persons speech signal in
  frequency domain
• Envelope of the FFT of the speech signal
• Used in speaker recognition because variations in
  a persons speech are minimized in the frequency
  domain compared to the time domain

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Vector Quantization Code Book

• Speaker Modeling
• Models of passwords are configured for specified
  compartment
• Creates a vector of centroids for each modeled
  word
• Classification
• Compares features from input signal with the
  features from the modeled words by calculating
  the differences
• Chooses the modeled word that produces the
  smallest difference
• Rejects the speaker if the minimum difference is
  not above a specified number (threshold)

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Matlab GUI Operation

• Add words to database from microphone or audio
  files
• Verify speaker and words from microphone or audio
  files
• Clear database for reconfiguration

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Design Changes

• Determined that Simulink is no longer needed
  were using Simulink to link Matlab and PIC but
  determined that Matlab will link directly with
  the microcontroller
• Built a Plexi-glass top because wood one warped
  in humidity and for demonstration purposes

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Design Advantages

• Wood construction allows for easy alteration
• Modular construction allows for easy removal of
  key parts if necessary
• Design allows for future modifications and
  upgrades (pinpad, LCD screen, etc)

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Disadvantages

• Will not be a stand alone prototype must rely on
  computer for most items
• Computer is slower than we would like for some
  calculations
• More users, longer calculation time

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Current Project Status

• Speaker identification complete
• Speaker verification 95 complete
• Prototype compartment built
• Matlab linking correctly with microcontroller
• Microcontroller turning motor

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Future Work

• Determine how to gear motor correctly
• Implement proper protection circuit for
  microcontroller
• Determine threshold for speaker verification with
  high quality microphone
• Test algorithm to increase accuracy
• Test links between all equipment
• Test motor control and turning
• Test entire unit
• QUESTIONS?