Renovated, redesigned, and manufactured an improved Assistive Robotic Arm from a pre-existing robotic arm for rehabilitation purposes amongst people suffering from a neuromuscular dysfunction.

1. • Team
• Tim Mikal
• Anthony Tilley
• Juddson Frost
• Allen Tan
• Supervisor:
• Dr. Kee Moon
CHAIR MOUNTED ASSISTIVE ROBOTIC ARM

2. CHAIR MOUNTED ASSISTIVE ROBOTIC ARM
• Project Description
• Design, analyze and fabricate a chair
mounted robotic arm assistive device
• Mechanism is engineered to assist people
who suffer from a decline in neuromuscular
function which causes weakness in the limbs

3. DESIGN ITERATIONS
• Interrupted Axle Concept• Original Design

4. PUGH MATRIX

5. 1ST SEMESTER FINAL
PROTOTYPE
ASSEMBLY

6. UPPER ARM
REINFORCEMENT
• FDM Plastic not rigid enough
• G10 reinforcement
• Increased stiffness
• Increased load carrying capability

7. 1ST SEMESTER STRESS & LOAD
CASE ANALYSIS
• Worst case loading scenario used for
analysis
• 8lbf arm load directly applied to end of
humorous component
• Perpendicular loading very conservative
• Factor of safety > 3

8. FRACTURE FAILURE
• FDM Plastic delaminated due to high stress
concentration
• Design originally intended for aluminum

9. NEW MATERIAL SELECTION
• 6061-T4 Aluminum
• Relatively easy to machine
• Relatively low cost
• Light weight
• Corrosion resistant

10. • 6061-T4 Aluminum
• Increased stiffness
• Increased load carrying capability
• F.S. = 4.8
• 6061-T4 Aluminum
• Increased stiffness
• Increased load carrying capability
• F.S. = 14

11. • 6061-T4 Aluminum
• Improved Motor interface
• Increased load carrying capability
• F.S. = 2.7
• 6061-T4 Aluminum
• Improved cuff interface
• Improved motor interface
• F.S. = 10

12. Mass Properties
Material = 6061-T4Aluminum
Density = 0.05 lb/in3
Mass = 2.84 pounds
Volume = 52.36 in3
Surface area = 329.36 in2

13. PROCUREMENT MATRIX (BILL OF MATERIALS)
McMaster Carr Part # Description QTY. Price Package count
Aluminum Block (50mm x 25mm x 10mm) (2.00in x 2.00in x 0.40in) Bearing Cap 5 $ 178.33 1
Aluminum Block (101mm x 83mm x 81mm) (3.98in x 3.26in x 3.2in) Shoulder arm part 1 1 - -
Aluminum Block (92mm x 61mm x 50mm) (3.622in x 2.4in x 1.97in) Shoulder arm part 2 1 - -
Aluminum Block (361mm x 55mm x 76mm) (14.22in x 2.16in x 3.00in) Humerous arm rev 2 1 - -
Aluminum Block (73mm x 30mm x 125.3mm) (2.9in x 1.15in x 5.00in) Forearm rev 2 1 - -
91801A224 Machine Screw M-0.7P, 20mm long 8 $ 9.66 50
5972K275 Bearing 6 $ 47.58 $7.93 each
90576A102 Lock Nut M3-0.5P 16 $ 3.18 100
95610A640 Nylon Washer 17ID,30OD,2.7mm thick 1 $ 6.75 25
92010A143 Machine Screw M3-0.5P, 35mm long 12 $ 10.38 50
92010A024 Machine Screw M2.5-0.45P, 14mm long 24 $ 5.91 100
92005A128 Machine Screw M3 20mm long 6 $ 3.00 100
BEARING CLAMPS FOR FINAL DESIGN 6$ 25.00 6
All Blk.(Blocks) will need be Multi Purpose Aluminum Alloy 6061 Total Cost $ 414.79

14. MATERIAL FITMENT

15. MACHINED FINAL ASSEMBLY

16. ACCOMPLISHMENTS
• New design removed unwanted loads from motors
• New design incorporates bearings that are securely mounted by new bearing clamps; are
double sealed, lubricated, and maintenance free
• New design provides a robust assembly that will serve as a reliable test bed for years
• Assembly was designed for function and ease of manufacture using 6061-T4 Aluminum
• Assembly proves the design tolerance and fit up considerations worked
• Mechanism is adjustable to fit different users

17. FURTHER DEVELOPMENT
• Stronger motors could help development phase
• Weight optimized structural member design to reduce need for bigger motors would
be helpful
• Adjustable forearm cuff could be advantageous

18. Questions?