Acoustic Navigation for Mobile Robots

Computer System DesignSpring 2003

BackgroundBackground

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 StatementProblem 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 ObjectiveDesign 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 SolutionsExisting Solutions

Phonotaxis – University of Stirling, Scotland4 microphone array to model female crickets homing in on the

sound of a male cricket

Signal Rectifier – Elliott Sound ProductsDeveloped an LED audio VU meter that uses simple full-wave

rectifier and pre-amplifier hardware circuitry

Existing Solutions (con’t)Existing Solutions (con’t)

Convict Episcopal de Luxembourg, Bouyette GroupSound SensorSound sensor that measures the difference in phase of two audio

signals to determine the source of the soundRobot searches for and advances toward pulsing sounds

Audio Frequency SensorA single microphone implementation that measures the pulses of the

audio signal to determine the frequency

Microphone ArrayMicrophone 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

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 DiagramProposed Design Diagram

Design ConstraintsDesign Constraints

Cost Size/Weight Compatibility Power Sound Frequency Range Environment Robot Mobility Single Tone Testing Time

Alternative SolutionsAlternative Solutions

Finding single largest amplitudeAnalog comparison and digital comparison

Digital Signal ProcessingBeamformingTime and amplitude differential

Design ValidationDesign Validation

Economic AnalysisEconomic Analysis

Societal, Safety, and Environmental Analysis

Societal, Safety, and Environmental Analysis

Electronics in societyManufacturing process chemicalsCapacitor, resistors, integrated circuit proper

usageWater hazardsProper power and ground sources

ManagementManagement

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.

SchedulingScheduling

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)