This project consists of a speech recognition module and a motorized robot controlled through voice commands. The speech recognition system is trained during a training phase by extracting the frequency components of spoken words, and tests input speech by matching it to the stored reference models. Correctly recognized commands are used to control a DC motor and move the robot forward or backward. The system uses an ADSP 2181 processor for signal processing and speech recognition through techniques like framing the speech signal, windowing, fast Fourier transform, mel filtering, and MFCC analysis to extract features from the input speech for recognition.

1. ROBOTIC CONTROL THROUGH SPEECH

2. INTRODUCTIONThis voice recognition project consists of two major components, a speech recognition module and a motorized robot.Programmable module allows us to write the programming in Visual DSP++ (Programming applications for the ADSP 2181 Architecture).The motorized robot will consist of two DC motors and will make the robot forward and backward directions. DEPARTMENT OF ECE2

3. PROJECT DESCRIPTION The Speaker Recognition can be classified into two phases. 1 Training Phase. 2 Testing Phase.DEPARTMENT OF ECE3

4. Training Phase.In Training Phase ,the frequency components of the given speech signal is extracted. Each registered speaker has to provide samples of their speech (given words).so that the system an build or train a reference model for that speaker.DEPARTMENT OF ECE4

5. Testing phaseIn testing phase ,the input speech is matched with stored references models (s)

6. Recognition decision is made on the basis of Mel Frequency Cepstrum Coefficients (MFCC)

7. The command recognition is observed by the operation of stepper motor & DC motor and the control signals to the DC motor DEPARTMENT OF ECE5

8. ARCHITECTURE OF ADSP 2181DEPARTMENT OF ECE6

9. FEATURES OF ADSP 2181 PROCESSOR25 ns Instruction Cycle Time from 20 MHz Crystal at 5.0 VoltsSingle-Cycle Instruction ExecutionMultifunction InstructionsLow Power Dissipation in Idle Mode16K Words On-Chip Program Memory RAM16K Words On-Chip Data Memory RAMIndependent ALU, Multiplier/Accumulator, and Barrel Shifter Units3-Bus Architecture Allows Dual Operand Fetches in every Instruction CycleDEPARTMENT OF ECE7

10. ALU and MACThe ALU performs a standard set of arithmetic and logic operations in addition to division primitives. The MAC performs single-cycle multiply, multiply/add and multiply/subtract operations.DEPARTMENT OF ECE8

11. SHIFTERThe shifter performs logical and arithmetic shifts, normalization, de-normalization, and derive exponent operations. The shifter implements numeric format control including multiword floating-point representations.DEPARTMENT OF ECE9

12. SPEECHThe input speech is given in the form of nos. like1, 2,3..The frequency range of human voice is 4kHz hence sampling frequency is taken as 8kHzIn coding only 2000 samples are considered because only 0.25 sec will be taken for one character10DEPARTMENT OF ECE

13. REPRESENTATION OF SPEECH SIGNAL11DEPARTMENT OF ECE

14. Block DiagramInput speech via mic ADSP 2181DEPARTMENT OF ECE12WINDOWINGFFTCODECFRAMMINGMELSPECTRUMMEL FREQWRAPMELCEPSTRUMDCMOTOR

15. FRAMINGSpeech signal is blocked into frames of N samples (n=256)Adjacent Frames are separated by M samples (M=100)Frame1= 0-256Frame2=100-356Such kind of 18 frames are required for 2000 samples/sec character.13DEPARTMENT OF ECE

16. FRAMING14DEPARTMENT OF ECE

17. WindowingMinimizes signal discontinuity in each frameReduced spectral distortionWindow signal is obtained by Y1(n)=x1(n)*w(n) ; 0<=n<N-1Where w(n) is Hamming Window and is given by w(n)=0.54-0.46Cos(2∏ n/N-1); 0<=n<N-115DEPARTMENT OF ECE

18. Windowing16DEPARTMENT OF ECE

19. Result of Windowing256 values are o/p of this processThese values are given as an input for FFT.Some values of windowingfor 1 kHz is shown 0x00000x08260x0BE60x08B70x000F0xF6C70xF26C0xF5FC0xFFE80x0AA90x0FC7 17DEPARTMENT OF ECE

20. Fast Fourier TransformConverts time domain signal into frequency domain signalPower spectrum is obtained with real and imaginary part of the frequency domain of the speech signal.18DEPARTMENT OF ECE

21. WrappingA subjective pitch for each frequency is computed using Mel ScaleMel frequency scale is given by mel(f)=2595*log10(1+f/700)19DEPARTMENT OF ECE

22. Mel Frequency Coefficients20DEPARTMENT OF ECE

23. MFCCIt is Mel Frequency Cepstrum CoefficientIt consists of various frequency coefficient components.It contains: Mel Spectrum (frequency domain) Mel Cepstrum (time domain)21DEPARTMENT OF ECE

24. SPECTRUMSamples are convoluted with mel filter bank to obtain mel frequency spectrum.Mel frequency spectrum is given by s(n)=y(n)*f(n) s(n)------>mel frequency spectrum y(n)------>samples f(n)------->filter coefficients22DEPARTMENT OF ECE

25. Inverse Discrete Cosine TransformationMel frequency power spectrum is in frequency domain functionIn order to obtain a time domain function the signal undergoes IDCTNow mel frequency spectrum is converted into mel frequency cepstrum. 23DEPARTMENT OF ECE

26. CEPSTRUMMFCC real numbers and are convoluted to time domain using IDCTThe time domain coefficients are called mel frequency cepstrum coefficients..MFCC is given by c(n)=sum of log (Sk * cos (n(k-.5)*pi/k) 24DEPARTMENT OF ECE

27. LEAST MEAN SQUARE ALGORITHM (LMS)This algorithm is used to find out the the minimum deviation between certain values.During testing phase the input speech is compared with the stored 4 values.The least deviated value is sent. 25DEPARTMENT OF ECE

28. INTERFACING PC WITH KIT RS-232 SERIAL CABLEDEPARTMENT OF ECE26PCDSP PROCESSOR

29. DSP TO DC MOTORDEPARTMENT OF ECE27

30. CIRCUIT DIAGRAMDEPARTMENT OF ECE28

31. HARDWARE DETAILSThe latched output from the latch IC is given to the relays via resistor and transistor.

32. According to the predefined input, the coil gets energized and relay is switched to ON position.

33. Here we use SPDT relay

34. It causes a current flow in the DC Motor.DEPARTMENT OF ECE29

35. Details of dc motorSpeed of the motor - 300 rpmCurrent – 750mAVoltage – 7.5VDEPARTMENT OF ECE30