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Self-Tuning Musical Chime. Mickey Heynen Beth Lopour Tyler Smith Experimental Engineering (ME 224) Professor Espinosa June 6, 2003. Outline. System Overview Mechanical System Experimental Setup and Procedure Demo Data Results. System Overview. 1. User inputs desired frequency
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Self-Tuning Musical Chime Mickey Heynen Beth Lopour Tyler Smith Experimental Engineering (ME 224) Professor Espinosa June 6, 2003
Outline • System Overview • Mechanical System • Experimental Setup and Procedure • Demo • Data • Results
System 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
5 1 3 4 2 Mechanical System -- Overview • Chime • Reservoir • Servomotor / Striker • DC motor / Pulley Rod • Microphone
Mechanical 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 System -- Specifics • Servomotor • Voltage:4.8V to 6V • Speed: .16 sec/60 degrees • Torque: 49 oz-in (3.57kg/cm) 6 volt
Data -- Correct frequency detected?
Data -- Accurate tuning?
Data -- Efficient tuning?
Results -- The Good News • 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
Results -- 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
Summary • 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
Possible Modifications • 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