Prosthetic Hand- Midpoint By: Jannell Broderick, Allison Cutler, Felicity Escarzaga, Toni Goss March 13, 2019
Project Description 2 Team 18F12 Active Prosthetic
Project Description This project aims to provide below-elbow amputees with an affordable prosthetic, that provides them with haptic feedback. Importance A prosthetic does more than replace a limb. It has the ability to make the wearer feel whole, have sense of belonging, feel unique, and enable their independence. Goss 3 Team 18F12 Active Prosthetic
Electronics Case Cuff Redboard Forearm Proposed Design Fall 2018 Battery Rear Forearm Spring Front Palm Current Forearm Current Finger Standard Servo motors (Tower Pro MG 996R) Micro Servo motor Thumb Fingers Current CAD Current Palm Current Cuff Goss 4 Current State Team 18F12 Active Prosthetic
Updates 5 Team 18F12 Active Prosthetic
Updates-Cuff Fall 2018 Early Spring 2019 Fall 2018 February 2019 ● Design adapted from e-Nable with Arduino Attachment [1] Early Spring 2019 Current Current Covers complete arm, adds assistant motor and ● + Includes attachment to forearm, allows for electronic covers, designed to be thermoformed two assistant springs, included new Arduino Late February 2019 (RedBoard) and LiPo battery ● Increase thickness and percent infill, cannot open, - Oversized attachment to forearm no longer thermoformed, motor removed, assistance springs added Escarzaga 6 Team 18F12 Active Prosthetic
Updates-Forearm Early Spring 2019 Model Fall 2018 Model Current Model Reason for Changes: 1. Discovered that thermoforming is not necessary Still Missing from Design: if wall thickness is 0.125” 1. Spring attachment on 2. Allows for the size of the servo motors back a. Has flat portion with indents for motors to 2. Way to connect to palm rest on 3. Easier to manufacture repeatedly Cutler 7 Team 18F12 Active Prosthetic
Updates-Palm Fall 2018- Palm was more basic ● with no opening for motor. Thumb had minimal movement January 2019- Palm adjusted ● with opening and for ball and socket attachment January 2019 February 2019- Continual ● Fall 2018 February 2019 adjustment to palm opening to allow for an easy assembly and for user to be able to adjust the wires and motor attachment. Thumb not was full mobility ● Current Model- Now includes better attachments for the forearm and fingers. More aesthetically appealing Goss 8 Current Team 18F12 Active Prosthetic
Updates-Fingers Last Week’s Model Fall 2018 Model Early Spring 2019 Model Reason for Changes: Still Missing from 1. Fingers were too thin Design: and weak 1. Rotating Thumb 2. No longer utilizing base rubber bands 2. Perfect hinge 3. New tendon channels pins 4. Channel for pressure 3. Palm Current Model sensors Attachments 5. Decrease thickness to 0.65 inches Broderick 9 Team 18F12 Active Prosthetic
Moving Forward 10 Team 18F12 Active Prosthetic
Analytical Analyses Finger Motion Simulation: ● Determined the location of finger tips and center of masses ○ ○ Helped to determine the movement of the artificial tendons ● Wireless Communication: ○ Relays information from pressure sensors at the toes to motors in the arm Determined type of wireless communication to be used: XBee ○ PID Control: ● Maps the analog input of pressure sensors to digital output of motors ○ ○ Control of motors is proportional to the pressure applied to the sensor and can hold position ● Pin Tolerance: ○ Allows for clearance, loose, and tight fits for different pins Important for all attachment points ○ Escarzaga 11 Team 18F12 Active Prosthetic
Manufacturing: What is Left? ● Cuff and Forearm: ● Code Communication ○ Lift and Motion Assistance ● Install Arduino ● Palm: ● Sensors Motor enclosure ○ ● Motors ● Fingers: ● Tendons ○ Thumb Range of Motion ● Connections: ○ Connect subsystems Broderick 12 Team 18F12 Active Prosthetic
● Code Communication: Manufacturing: Plan ○ Code arduino to control ● Cuff and Forearm: movement and sensory response ○ Spring attachment ● Install Arduino: ○ Dimensions (less Bulky) ● Palm: ○ Attach Arduino Hardware to prosthetic Adjust cover and motor ○ ● Sensors: placement. Improve forearm ○ Connect to arduino Hardware attachment ● Motors: ● Fingers: Install hardware motors and ○ ○ Thumb Rotating Base attach to arduino ● Connections: ● Tendons: Print subsystems and ○ Thread through channels ○ Attach to Motors respective attachments (pins, ○ hinges, etc.) Broderick 13 Team 18F12 Active Prosthetic
Plans for Testing 1. Test print a smaller and larger arm to determine if the CADs are scalable 1. Scalable Size 2. Compare prosthetic weight to human arm weight. (6-18 in) Within 5% 2. Weight (<2 lbs) 3. Tally receipts 3. Budget ( ~ $500) 4. Durability (<10 lbs) 4. Durability will be tested multiple ways: a. Releasing a mallet from a 90 angle into the 5. Force to Actuate prototype for a number of cycles (< 5 lbf) b. Lift up to 10 lbs using only the prosthetic 6. Force of Grip 5. The pressure sensors in the insole measure up to 1 (<2 lbs) lbf 7. Number of Parts 6. Use fishing gage when an object is lifted (<100) 7. Tally parts in final prototype Cutler 14 Team 18F12 Active Prosthetic
Schedule & Budget 15 Team 18F12 Active Prosthetic
Schedule Cutler 16 Team 18F12 Active Prosthetic
Schedule Cutler 17 Team 18F12 Active Prosthetic
Budget Current Spending Cutler 18 Estimate Budget Team 18F12 Active Prosthetic
References [1] “Enabling The Future,” Enabling The Future . [Online]. Available: http://enablingthefuture.org/. [Accessed: 10-Oct-2018]. 19 Team 18F12 Active Prosthetic
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