Project Number: MQPWZM-RB08 MQPECC-B708 The Thumper Robotic Bass A Major Qualifying Project Report Submitted to the Faculty Of the Worcester Polytechnic Institute In partial fulfillment of the requirements for the Degree of Bachelor of Science By ______________________________________ Matt Brown, Electrical and Computer Engineering, Class of 2008 ______________________________________ Barry Kosherick, Electrical and Computer Engineering, Class of 2009 ______________________________________ Adam Teti, Mechanical Engineering, Class of 2008 April 18, 2008 ________________________________ Prof. William R. Michalson, Co-Advisor ________________________________ Prof. Eben C. Cobb, Co-Advisor Abstract The Thumper Robotic Bass MQP is an attempt at creating a self-playing bass guitar that responds to MIDI input as well as input from an electric guitar to provide accompaniment. By bringing together a team of electrical and mechanical engineers, the project was structured to emulate an engineering design as encountered in industry. Table of Contents Introduction .................................................................................................................................................. 1 Problem Statement ................................................................................................................................... 1 Background ............................................................................................................................................... 2 Economics and Target Market .................................................................................................................. 3 System-Level Requirements ..................................................................................................................... 4 Electrical Design ............................................................................................................................................ 5 Note Detection .......................................................................................................................................... 5 Circuit .................................................................................................................................................... 8 Circuit Simulation .................................................................................................................................. 9 Layout and Fabrication ....................................................................................................................... 10 Chord Detection ...................................................................................................................................... 10 Circuit .................................................................................................................................................. 12 Solenoid Driver ........................................................................................................................................ 12 Solenoid Driver Circuit Layout ............................................................................................................ 13 Stepper Motor Driver Circuit, Layout and Fabrication ....................................................................... 15 Control .................................................................................................................................................... 17 MIDI Interface ..................................................................................................................................... 19 Solenoid Control ................................................................................................................................. 23 Motor Control ..................................................................................................................................... 24 Power .................................................................................................................................................. 25 Mechanical Design ...................................................................................................................................... 26 Fretting .................................................................................................................................................... 26 Design Concepts .................................................................................................................................. 26 Solenoids ............................................................................................................................................. 29 Solenoid Mounts ................................................................................................................................. 31 Plucking ................................................................................................................................................... 32 Design Concepts .................................................................................................................................. 33 Linkage .................................................................................................................................................... 36 Motors ................................................................................................................................................. 36 Design .................................................................................................................................................. 36 Kinematic Analysis .............................................................................................................................. 37 Dynamic Analysis ................................................................................................................................ 37 Stress and Deflection Analysis ............................................................................................................ 41 Frame ...................................................................................................................................................... 42 Design .................................................................................................................................................. 42 Analysis ............................................................................................................................................... 44 Safety .......................................................................................................................................................... 44 Recommendations for Further Work .......................................................................................................... 45 Conclusion ................................................................................................................................................... 46 Appendix – VHDL Code ............................................................................................................................... 48 UART Core ............................................................................................................................................... 48 uart_lib.vhd ......................................................................................................................................... 48 clkUnit.vhd .......................................................................................................................................... 49 RxUnit.vhd ........................................................................................................................................... 52 TxUnit.vhd ........................................................................................................................................... 55 miniUART.vhd ..................................................................................................................................... 58 MIDI Interpreter ...................................................................................................................................... 62 MIDI_Interpreter.vhd .......................................................................................................................... 62 miditbl_TB.vhd .................................................................................................................................... 67 Stepper Motor Control............................................................................................................................ 72 stepper_drive.vhd ............................................................................................................................... 72 stepper_drive_tb.vhd ......................................................................................................................... 75 Appendix – Mechanical Drawings ............................................................................................................... 79 Table of Figures FIGURE 1 - TOP LEVEL BLOCK DIAGRAM .................................................................................................................................. 1 FIGURE 2 - (LEFT ) THE P.E.A.R.T. FROM UNIV . OF LOUISIANA AND (RIGHT ) THE LEMUR GUITAR BOT ............................................. 2 FIGURE 3 - STILL FROM ANIMUSIC 2 DVD "R ESONANT CHAMBER " .............................................................................................