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

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

3. 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

4. Existing Designs Transperformance –Price >$4500 –Alternate tunings –Open loop / Closed loop control © Transperformance 2004 www.transperformance.com

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

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

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

8. Micro

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

13. 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

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

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

16. How it works

18. Questions?