Wednesday, April 16, 2008

The PeanutBot!

” The PeanutBot robot consists of three microphone circuits, three servo motors, an MCU and a PC. The three microphones were used to triangulate the angle of the source relative to the robot. The audio source plays a continuous stream of pulses. Pulses were chosen over a continuous tone because, instead of detecting phase difference in the audio signal, our system detects the arrival time of the signal at a certain amplitude at each microphone. The robot is designed to be autonomous and is, therefore, not synchronized with the pulse generator. As a result, the time of flight of each impulse is not available and the robot is unable to quantify the distance to the source. Instead, the robot advances by a small predetermined distance and listens for the signal again. To find the sound source, the robot listens for the arrival of an impulse on any of the three microphones. Once an impulse has been detected at one of the microphones, the robot records the microphone data at 10 microsecond intervals for 10 milliseconds. Using this data, the arrival time of the impulse at e! ach microphone is calculated and the direction of the source is obtained. Once the angle of the source has been identified, the robot rotates and pursues the source for a short period, and then promptly resumes triangulation of the signal to repeat the process.”


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