Self-Tuning Musical ChimeSelf-Tuning Musical Chime

Mickey Heynen

Beth Lopour

Tyler Smith

Experimental Engineering (ME 224)

Professor Espinosa

June 6, 2003

OutlineOutline

• System Overview

• Mechanical System

• Experimental Setup and Procedure

• Demo

• Data

• Results

System OverviewSystem Overview

1. User inputs desired frequency

2. Chime is struck, and LabVIEW determines frequency of resulting tone

3. Actual frequency is compared to target frequency

4. DC motor raises or lowers the chime

4. Steps 2-4 are repeated until target frequency is reached

5. Chime is struck again, sound is recorded

Mechanical SystemMechanical System

1. Chime

2. Reservoir

3. Servomotor / Striker

4. DC motor / Pulley Rod

5. Microphone

1

2

34

5

-- Overview

Mechanical SystemMechanical System -- Specifics

DC Gear Motor

• Operating range: 4.5VDC to 12VDC • No load current: 48mA • No load speed: 44rpm • Current @ Max efficiency : 172mA • Speed @ Max efficiency: 35rpm • Torque with load @ max efficiency: 2.37kg/cm • Gear ratio: 100:1

Mechanical SystemMechanical System -- Specifics

Servomotor

• Voltage:4.8V to 6V • Speed: .16 sec/60 degrees• Torque: 49 oz-in (3.57kg/cm) 6 volt

Experimental Setup and ProcedureExperimental Setup and Procedure

Experimental Setup and ProcedureExperimental Setup and Procedure

DemoDemo

DataData -- Correct frequency detected?

Calculated output frequency: 616 HzActual output frequency: 614.786 Hz

1000 1200 1400 1600 1800 2000

Data point #

DataData -- Accurate tuning?

Target Frequency vs. Actual Frequency

585

590

595

600

605

610

615

620

1 2 3 4 5 6 7 8 9 10

Attempt #

Fre

qu

ency

(H

z)

Actual Frequency Target Frequency

-- Efficient tuning?DataData

Target Frequency vs. Actual Frequency

590

595

600

605

610

615

620

1 2 3 4

Attempt #

Fre

qu

en

cy

(H

z)

Actual Frequency Target Frequency

ResultsResults

• Irregularities in waveform do not hinder detection

• Tuning tolerance is ± 1 Hz

• Smaller frequency adjustments as target value is reached

• Adjustments are possible in two directions

-- The Good News

ResultsResults -- The Bad News

• Range is very small: 585-925 Hz

• Efficiency depends on luck

• System limited by length of chime; tone rapidly deteriorates when submerged

• If frequency leaves predicted range, crashes or endless loops can occur

• User is responsible for emergency stops

SummarySummary

• Project objectives were accomplished

• Combined familiar and unfamiliar concepts:- Analog to digital data acquisition- LabVIEW user interfaces and logic programs- Methods of signal filtering and processing- Use of a microphone as a sensor- Types of motor control via the DAQ board

• Good foundation – many variations are possible

• Multiple chimes for a wider range of pitches

• System records a string of notes and plays them back at the end

• The system could play in “real-time”

- Separate calibration program

- Digital encoder and faster dc motor

- Piano key user interface

Possible ModificationsPossible Modifications

QuestionsQuestions

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