School of Mechanical Engineering Project number 180: Design and Build of a self tuning stringed instrument Andrew LeonardColin Love

Project Outline Based around conventional 6 stringed electric guitar Consists of 3 main components Data acquisition Control system Mechanical tensioning system

Design Specifications Lightweight Keep structural integrity Keep existing manual tuning Remain tuned without power supplied to system Quick and Accurate Cheap (less than $1500) Retain existing size and shape

Existing Designs Transperformance –Price >$4500 –Alternate tunings –Open loop / Closed loop control © Transperformance

Rochester Institute of Technology –Student group to design self tuning guitar –Utilised a FFT algorithm –Incremental control –Extremely unreliable Existing Designs

Our Solution Completely internal Used for fine tuning Levers to adjust tension P- control

Data Acquisition system Midi Pickup Each signal generated in separate coils Conventional Pickup All signals combined in one coil

Micro

Control system Pulsed information from signal refining circuit Used 6 PICs; one for each string –Existing knowledge base –Cheap –Easy to program

Control Algorithm T1T1 T2T2 Time between consecutive rising edges measured Valid signals are stored in an array Motors activated when 8 consecutive valid signals are received Predefined set-point Last 8 set-point errors averaged and P-control utilised

Motor Control Speed controlled by pulse width modulation Micro PWM Direction Motor Driver DC Motor

Mechanical System In-body Design –Motors with low speed/high torque gearboxes –Threaded rod – linkage – lever

How it works

Questions?