Acoustic Navigation for Mobile Robots Computer System Design Spring 2003
Background Microphone arrays have been in use for over 30 years. Array can outperform even the best directional microphones. Digital conversion increases possibilities of realistic implementations. Applicable in conference rooms/auditoriums, concerts, surveillance equipment and robotic designs. Rutgers University developed 380 microphone array system proving the usefulness of this technique.
Problem Statement Design an acoustic navigation module with the ability to detect sound in a 360°environment using a microphone array that will allow a mobile robot to perform movement based on sound location.
Design Objective Develop a printed circuit board interface for the microphone array Design acoustic fixtures to increase directionality of microphones Develop algorithms to determine the angle and position of the transmitted sound Design must be able to detect certain frequency ranges in which the robot will respond differently based on the frequency received.
Existing Solutions Phonotaxis – University of Stirling, Scotland 4 microphone array to model female crickets homing in on the sound of a male cricket Signal Rectifier – Elliott Sound Products Developed an LED audio VU meter that uses simple full-wave rectifier and pre-amplifier hardware circuitry
Existing Solutions (con’t) Convict Episcopal de Luxembourg, Bouyette Group Sound Sensor Sound sensor that measures the difference in phase of two audio signals to determine the source of the sound Robot searches for and advances toward pulsing sounds Audio Frequency Sensor A single microphone implementation that measures the pulses of the audio signal to determine the frequency
Microphone Array Implementing 8 microphones, allowing each microphone 45° of coverage. Electret microphones – best compromise between response, cost, and ease of design. To increase directionality, we will implement a sound dampening system.
Proposed Hardware Design Interface the Coldfire 8-bit UART 4-bit Signal Resolution 3-bit representation of selected microphone 1-bit to represent filter type Each microphone polled sequentially Clock and counter to perform polling
Proposed Design Diagram
Design Constraints Cost Size/Weight Compatibility Power Sound Frequency Range Environment Robot Mobility Single Tone Testing Time
Alternative Solutions Finding single largest amplitude Analog comparison and digital comparison Digital Signal Processing Beamforming Time and amplitude differential
Design Validation
Economic Analysis
Societal, Safety, and Environmental Analysis Electronics in society Manufacturing process chemicals Capacitor, resistors, integrated circuit proper usage Water hazards Proper power and ground sources
Management Trent Foley Lead hardware design engineer, documentation. Josh Earley Development of mic array, acoustic directionality, board design. Chris Gonzales Software design, budget, procurement of parts. Thomas Garner Lead software engineer, board design.
Scheduling M 6:15 p.m. (meeting with advisors) M-W-F 1:30 p.m. - 4:00 p.m. (regular design meetings) Weekends open (when necessary)