• Team• Tim Mikal• Anthony Tilley• Juddson Frost• Allen Tan

• Supervisor:• Dr. Kee Moon

CHAIR MOUNTED ASSISTIVE ROBOTIC ARM

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

DESIGN ITERATIONS• Interrupted Axle Concept• Original Design

PUGH MATRIX

1ST SEMESTER FINALPROTOTYPE ASSEMBLY

UPPER ARM REINFORCEMENT

• FDM Plastic not rigid enough• G10 reinforcement• Increased stiffness• Increased load carrying capability

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

FRACTURE FAILURE• FDM Plastic delaminated due to high

stress concentration• Design originally intended for

aluminum

NEW MATERIAL SELECTION• 6061-T4 Aluminum

• Relatively easy to machine• Relatively low cost• Light weight• Corrosion resistant

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

SHOULDER JOINT

REDESIGN

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

SHOULDER

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

FOREARMREDESIGN

• 6061-T4 Aluminum• Improved cuff interface• Improved motor interface• F.S. = 10

HUMOROUS

REDESIGNED ASSEMBLY

Mass PropertiesMaterial = 6061-T4Aluminum

Density = 0.05 lb/in3

Mass = 2.84 pounds

Volume = 52.36 in3

Surface area = 329.36 in2

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

MATERIAL FITMENT

MACHINED FINAL ASSEMBLY

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

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

Questions?