Design of a Human Hand Prosthesis Paul Ventimiglia Liberal Arts & Engineering Advisors: Taskin Padir and Jerome Schaufeld Abstract Current prosthetic hands have limited functionality and are cost prohibitive. A design of a cost effective anthropomorphic prosthetic hand was created. The novel design incorporates five individually actuated fingers in addition to powered thumb roll articulation, which is unseen in commercial products. Fingertip grip force is displayed via LEDs for feedback control. The hand contains a battery and micro- controller. Multiple options for signal input and control algorithms are presented. A prototype will serve as a platform for future programming efforts. Functional Requirements  5 individually articulated fingers + thumb roll  Can pick up and hold:  Dime, spoon/fork, common cups/bottles  Less than 450g total weight  Minimum power-grip force of 150N  Minimum pinch-grip force of 15N  Multiple user-control input options  Less than $3,000 to produce (Quantity 1x) Key Features  Completely self contained  Cosmetic plastic covers  6 degrees-of-freedom  Individually articulated  Fingertip force measurement  Variable LED visual feedback  1.4 second grasp time from fully open to closed power grip  410 grams total weight (including battery) Conclusions  A complete mechanical design and prototype were produced  Worm gear joints and linkages provided compact packaging  A solution for an integrated thumb roll gearbox was developed  Many COTS components allowed for cost reduction  There is room in the market for lower cost prosthetic options Future Recommendations  User testing and analysis for ease of use and controllability  Programming new grip algorithms  Additional force sensor integration on multiple fingers  Wireless control through external signal inputs  Durability and strength testing of prototype Finger Joint Drivetrain  DC-brushed motor with 250:1 spur gear reduction  12:1 48 DP worm gear final reduction  2-start leads for increased efficiency  Anti-backdrive allows for constant fingertip holding force without active power application  Precision ball bearings for transmission  7075 Aluminum axles Grip Mode Examples Power Grip (all fingers are powered) Open Palm Grasp (thumb remains open) Key Grip (thumb is powered) Precision Pinch (index finger is powered) Finger pivot joints Thumb joint/gearbox Lithium polymer battery (on back) Compound thumb gearbox ½-20 stud universal mount Thumb roll motor Main finger motors/gearboxes Rubber grip lining on fingers Control Considerations  Arduino Pro Mini for I/O and onboard processing  Analog potentiometers measure the rotational position of each finger joint  Fingertech TinyESC motor controllers  Open source serial input allowing for multiple signal input options  Myoelectric  Toe-operated wireless switches  Multiple grip mode algorithms Example of commonly used prosthetic hook Manufacturing Considerations  Utilization of many COTS components when applicable  Entire cost to build fully functional prototype is $2,500  Several plastic components were designed for plastic injection molding  Universal components used extensively throughout the design Finger Linkage Motion  Single driven joint  4-bar linkage provides human-like motion of the finger tip  Finger tips act as a spring in series to provide constant holding force and impact absorption  Conformal gripping of common objects