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Imaginary Drum Kits. Hyemin Chung and Jaewoo Chung May 17 th , 2005. Backgrounds. Theremin. Spirit Chair. Expressive Footwear. Digital Baton. Goal. Mobile full drum kit without real drums or instruments Can detect hitting positions. By capacitive sensing
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Imaginary Drum Kits Hyemin Chung and Jaewoo Chung May 17th, 2005
Backgrounds Theremin Spirit Chair ExpressiveFootwear Digital Baton
Goal • Mobile full drum kit without real drums or instruments • Can detect hitting positions. • By capacitive sensing • Can detect hitting timing and velocity. • By accelerometers • Can be easily moved and carried. • Can run without external installations.
Implementation CapacitiveSensingTransmitters Circuitsin the bag Accelerometers CapacitiveSensingReceivers
PIC16F88 Structure Sounds TX0 TX1 TX2 Visuals Stick0 Stick1 RX0 AC 0 RX1 AC 1
Capacitive Sensors • Detect the location of the drum sticks. • Use 3 transmitters to calculate the location. • Work in transmit mode. • To minimize the noise from the body • Transmitters are on the body. • Receivers are in the sticks. • Are sampled by 60 times and averaged.
Transmitters Receiver Capacitive Sensors
Sense the position Capacitive Sensors
OP Amp • MAX475 • Uses a high pass filter to avoid 60Hz noise.
Accelerometers • ADXL311JE • At the tips of the drum sticks • Detect the impact and velocity.
PIC • Controls the capacitive sensing. • Converts analog signals of accelerometers and capacitive receivers to digital data. • Sends data to the computer every 5 milliseconds.
Software • Detects the impact • Calculates the position of the drum sticks • Generates sounds and visual effects
Difficulties • Sensing area is larger than the sensor-area. • Lots of noise come from user’s body and all around the world. • Sticks bounce, re-bounce, and go up again. • Base levels ceaselessly vary by user’s movements or shapes. • Delay is a big problem in musical instrument systems.
Future Works • To make it more accurately by more tuning and noise deduction • To detect and apply the velocity of hitting • To make more portable, wearable, and compact