DESIGN AND ASSESSMENT OF AN UPPER EXTREMITY PROSTHETIC SYSTEM By Daniel Alvin Bennett Dissertation Submitted to the Faculty of the Graduate School of Vanderbilt University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY In Mechanical Engineering May, 2016 Nashville, Tennessee Approved: Professor Michael Goldfarb, Ph.D. Professor Robert J. Webster III, Ph.D. Professor Nilanjan Sarkar, Ph.D. Professor Eric J. Barth, Ph.D. Professor Gerasimos Bastas, M.D., Ph.D. To my parents, Dana and Lisa Bennett, who have supported me financially through college, emotionally through graduate school, and who believe in me in the way only parents can. Maybe now I will finally get a real job. ii ACKNOWLEDGEMENTS The work presented in this document is the summation of my individual contribution to the upper extremity prosthesis project, but it is by no means a product solely created by my own efforts. There are many people who have helped me a great deal throughout my time in the Center for Intelligent Mechatronics, and without whom the work presented here would have been impossible. Foremost among these is my advisor, Professor Michael Goldfarb, who has guided me over the last five years and has helped my project be the best that it could be. I am particularly thankful for the trust he places in his graduate students to manage their own time and projects, which encouraged me to be productive without making graduate school into something that is all- consuming in my life. I would also like to thank Profs. Sarkar, Webster, Barth, and Bastas for serving as my committee. The funding for this project has two major sources: the National Institutes of Health (NICHD R21HD068753) and the King Abdulaziz City for Science and Technology (KACST). I would like to thank these institutes for supporting my work and my stipend, and specifically I’d like to thank Dr. Khalid Aldakkan, a former CIM member who facilitated the partnership with KACST, and has provided much support, financial and otherwise, over the course of the project. The transhumeral prosthesis project has had many contributors over the years, some of whom began the project before I arrived and performed the work that was foundational to my own research, others who have worked alongside me for my entire tenure here, and still others who have come and gone. Tuomas Wiste performed the initial mechanical design of the hand, creating the skeletal anthropomorphic prototypes that gave me a great starting point for my own designs. Drs. Skyler Dalley and Atakan Varol designed the controllers for the Vanderbilt Multigrasp Hand, and I was able to work alongside Dr. Dalley specifically for several years as we developed and iii tested the hand prototype. He probably taught me more about my project and building robotic prosthetics than anyone, and it was a pleasure to work with him before he graduated. Don Truex is a wizard when it comes to designing and troubleshooting electronics, and his infinite patience in answering my incessant electronics and coding questions was instrumental in my project. Without his guidance and expertise, my project would have easily taken twice as long. Dr. Jason Mitchell is a fantastic mechanical design engineer who primarily worked on the transfemoral prosthesis project, but was always willing to answer my design questions, and later provided his expertise to design the powered elbow prosthesis. Nasser Alshammary has worked alongside me on the arm team for several years now, and has been a great help in designing the coordinated control schemes for the elbow and wrist joints. Malik Alshareef, Ibraheem Redhwi and Hisham Alhassnan were all here for a shorter time, but also contributed to the design of the transhumeral prosthesis. I would also like to thank all members of the CIM, past and present, for providing such an enjoyable work environment over the years. I am extremely grateful that I have been able to think of all of you as friends more than just co-workers, which has made all the difference for my experience in graduate school. Specifically, I'd like to mention Ben Gasser, who has frequently served as a sounding board for my design ideas, giving me great feedback, ideas, and design critiques. I would also like to thank Brian Lawson, who has helped me in a similar fashion for much longer, and from whom I have shamelessly stolen my dissertation format. If any future CIM members are reading this for the same reason, you should feel similarly obligated to cite me. iv TABLE OF CONTENTS Page DEDICATION ................................................................................................................................. i ACKNOWLEDGEMENTS ........................................................................................................... iii LIST OF TABLES ....................................................................................................................... viii LIST OF FIGURES ....................................................................................................................... ix ABBREVIATIONS ....................................................................................................................... xi Chapter I. Introduction .............................................................................................................................. 1 1. Upper Extremity Amputee Demographics and Needs .................................................... 2 2. Overview of Current State of the Art for Upper Extremity Prosthetics .......................... 3 3. Multi-joint Prosthesis Control Methodologies ................................................................ 5 4. Prior Work on Vanderbilt Transhumeral Prosthesis ....................................................... 7 4.1 Vanderbilt Multigrasp Hand ....................................................................................... 7 4.2 Multigrasp Myoelectric Controller (MMC) ................................................................ 9 II. Design of the Vanderbilt Multigrasp Hand ........................................................................... 12 1. Manuscript 1: A Multigrasp Hand Prosthesis for Providing Precision and Conformal Grasps .................................................................................................................................... 13 1.1 Abstract ..................................................................................................................... 13 1.2 Introduction ............................................................................................................... 13 1.3 Performance and Functional Objectives ................................................................... 14 1.3.1 Grasps and Postures .......................................................................................... 14 1.3.2 Digit Forces and Speeds.................................................................................... 15 1.3.3 Physical Properties ............................................................................................ 16 1.3.4 Power Consumption .......................................................................................... 16 1.4 Multigrasp Hand Design ........................................................................................... 17 1.4.1 Allocation of Actuation for Precision and Conformal Grasping ...................... 17 1.4.2 Tendon Actuation and Series and Parallel Elasticity ........................................ 21 1.4.3 Motor Unit Design ............................................................................................ 24 1.4.4 Cosmesis and Construction ............................................................................... 24 v 1.4.5 Embedded System Design ................................................................................ 25 1.5 Characterization of Hand Performance ..................................................................... 27 1.5.1 Hand Size and Mass .......................................................................................... 27 1.5.2 Fingertip Forces ................................................................................................ 28 1.5.3 Motion Bandwidth ............................................................................................ 30 1.5.4 Hand Postures and Grasps ................................................................................ 31 1.5.5 Battery Life ....................................................................................................... 32 1.6 Conclusion ................................................................................................................ 33 2. Addendums to Manuscript 1 ......................................................................................... 34 2.1 VMG Design Iterations ............................................................................................. 34 2.2 Functional Assessment of the Vanderbilt Multigrasp Hand ..................................... 39 2.3 Winding Temperature Estimation and Regulation for Brushless DC Motors .......... 44 III. Design of a Transhumeral Prosthesis .................................................................................... 49 1. Manuscript 2: Design of a Myoelectric Transhumeral Prosthesis ................................ 50 1.1 Abstract ..................................................................................................................... 50 1.2 Introduction ............................................................................................................... 50 1.3 Design Objectives ..................................................................................................... 56 1.3.1 Wrist Objectives................................................................................................ 56 1.3.2 Elbow Objectives .............................................................................................. 60 1.4 Design of Arm Components ..................................................................................... 63 1.4.1 Wrist Design ..................................................................................................... 63 1.4.2 Elbow Design .................................................................................................... 65 1.4.3 Embedded System Design ................................................................................ 67 1.5 Performance Characteristics ..................................................................................... 70 1.5.1 Range of Motion, Size and Mass ...................................................................... 70 1.5.2 Joint Speed Measurement ................................................................................. 72 1.5.3 Joint Torque Measurement ............................................................................... 76 1.5.4 Power Measurements and Battery Life ............................................................. 77 1.5.5 Audible Noise Measurement............................................................................. 80 1.6 Conclusion ................................................................................................................ 80 2. Addendums to Manuscript 2 ......................................................................................... 81 2.1 Powered Wrist Rotator Design Iterations ................................................................. 81 IV. Coordinated Control of a Prosthetic Wrist ............................................................................ 85 1. Manuscript 2: Intertial-Measurement-Based Synergistic Wrist Rotation Control for a Myoelectric Arm Prosthesis .................................................................................................. 86 1.1 Abstract ..................................................................................................................... 86 1.2 Introduction ............................................................................................................... 86 1.3 Coordinated Control Approach ................................................................................. 89 1.4 Assessment Procedure .............................................................................................. 92 1.4.1 Prosthesis Prototype .......................................................................................... 92 1.4.2 Able-bodied Adapter and Motion Capture ....................................................... 94 1.4.3 Obtaining Arm Angles from IMU Measurements ............................................ 95 1.4.4 EMG Measurement ........................................................................................... 97 vi 1.4.5 Assessment Tasks ............................................................................................. 97 1.5 Results ..................................................................................................................... 100 1.6 Discussion ............................................................................................................... 103 1.7 Conclusion .............................................................................................................. 104 2. Addendums to Manuscript 3 ....................................................................................... 105 2.1 IMU Data Interpretation and Sensor Fusion ........................................................... 105 2.1.1 Mathematical Representations of Rotation ..................................................... 105 2.1.2 Sensor Fusion .................................................................................................. 107 2.1.3 Calculating Orientation from Reference Vectors ........................................... 108 V. Conclusion ........................................................................................................................... 113 1. Recommended Future Work ....................................................................................... 114 REFERENCES ........................................................................................................................... 115 vii LIST OF TABLES Table Page III-1. Wrist and Elbow Performance Characteristics. .............................................................. 73 III-2. Wrist and Elbow Power Usage. ...................................................................................... 78 IV-1: Coordinated controller parameters. ................................................................................ 93 IV-3: Statistical analysis of coordinated controller compared with sequential controller. .... 103 IV-2: Performance data for the coordinated and sequential controllers. ............................... 103 viii LIST OF FIGURES Figure Page I-1. Comparison of the 3 generations of the VMG. ................................................................... 8 I-2. Graphical representation of the MMC state machine. ....................................................... 10 II-1. Allocation of actuation in hand prosthesis. ...................................................................... 18 II-2. Cross-sectional view of (a) digit II and (b) digit III. ........................................................ 22 II-3. Exploded view of motor unit, including clutch and pulley. ............................................. 24 II-4. Top and bottom views of hand embedded system. .......................................................... 25 II-5. Hand board embedded system architecture...................................................................... 26 II-6. Hand with cover removed, showing embedded system and motor units. ........................ 27 II-7. Fingertip Forces corresponding to each motor unit. ........................................................ 29 II-8. Bandwidth corresponding to each motor unit. ................................................................. 30 II-9. Canonical grasps and postures provided by the hand prosthesis. .................................... 31 II-10. First iteration of third generation VMG actuation scheme. ........................................... 35 II-11. Self-locking cam mechanism for bidirectional tendon tightening. ................................ 37 II-12. Southampton Hand Assessment Procedure (SHAP). ..................................................... 40 II-13. Able bodied adapter used in SHAP assessments. .......................................................... 41 II-14. Amputee subject performing a SHAP pouring task. ...................................................... 42 II-15. Progression of SHAP scores over time. ......................................................................... 43 II-16. Heat transfer diagram for motor thermal model. ........................................................... 45 II-17. Plots illustrating the test of the duty cycle attenuation algorithm.. ................................ 47 III-1. CAD model of wrist unit ................................................................................................ 64 III-2. Elbow prosthesis prototype ............................................................................................. 66 ix III-3. Block diagram of arm embedded system. ....................................................................... 68 III-4. Top and bottom view of arm embedded system. ............................................................ 69 III-5. Labeled photograph of fully assembled arm prosthesis.................................................. 70 III-6. Solid models and corresponding photographs of elbow prosthesis illustrating its ROM71 III-7. Closed loop position tracking bandwidth for each wrist transmission configuration. .... 74 III-8. Closed loop position tracking bandwidth for elbow. ...................................................... 75 III-9. First generation of wrist prototype.................................................................................. 82 III-10. Side-by-side comparison of the first and final versions of the wrist. ........................... 84 IV-1: Diagram showing location of IMU on arm and motions used in the coordinated controller. .................................................................................................................................................. 90 IV-2: Wrist controller configurations used in assessment. ...................................................... 91 IV-3: Able-bodied adapter.. ..................................................................................................... 94 IV-4: Subject performing Clothespin Relocation Test (CRT). ................................................ 95 IV-5: Diagram illustrating the procedure of the Compound Manipulation Task (CMT). ....... 99 IV-6: Mean task completion time and standard deviations. ................................................... 101 IV-7: Torso displacement means and standard deviations. .................................................... 102 x