The document outlines the design and development process of a robotic gripper by Jack and Jeremiah Gill for Autotech, focusing on constraints, initial and final designs, and assembly issues. The final design weighs 522.19 grams, comprises 137 parts, and can grip objects up to 80mm wide. Issues such as weight, the gripper's width, and part accessibility are noted as design drawbacks.

1. Jack Gillies & Jeremiah Gill
For AUTOTECH 2AC3
Instructor: Lucian Balan
SOLIDWORKS DESIGN
AND SIMULATION
PROJECT
March 19th, 2015

2. Constraints:
-Must be able to grip 3 prismatic shapes:
-Must be controlled by given servo motor, 5 rotations to close/open
-Must fit onto standard robot tool interface
-All parts must be able to be manufactured
-Assembly without interference
-Must use standard fasteners
-Robust and self-contained

3. Final Design

4. Final Design

5. Redesign
- After we finished the modeling, we realized the gripper isn’t
big enough to fit the cube
- We measured the cube face to face and ignored the
hypotenuse length of the cube
- Redesign took about 10 hours – Would have been easier if
we modeled more parametrically.

6. Final Design
-522.19 grams
-137 parts, 32 Unique parts
-Can grip objects up to 80mm in
width
- 84.3 mm maximum height from
arm interface
- 194 mm maximum width (to back
of servo)

7. Final Design

8. Assembly Animation

10. Inspiration
-Camera Shutter closes equally around central point
-Will make contact without lateral slip with any part.
-Operates by turning overlapping “leaves” towards inside
-Leaves are turned by pins which are driven by a central
turning ring

11. Initial Design
-5 Leaves overlapping (2mm thick)
-Leaves Spaced by washers of same thickness
-Assembly held in by retaining ring

13. Initial Design
-5 Pins of varying length (increments of 2mm) to turn the
leaves
-Pins are pushed through slots in turning ring
-Portion of bevel gear drives turning ring

14. Issues
-Overlap of leaves may cause “tipping” or
rocking of gripped piece
-We decided to mirror whole assembly so 2
apertures grip piece at different heights

15. Retaining Case
-Revolved profile of all turning parts to
create casing to retain rotational motion
-Mounting features for Motor assembly
-Identical mounting brackets for M6 bolts
-Upper holes machined for M4 screws to
hold in upper leaf base.
-This part will probably have to be casted
in aluminum.

16. Drive Train
-Total ratio needed is 39/1800 (turning ring degrees
per motor degree)
-Simple bevel gear and pinion would not be suitable
-Additional gears achieve following ratio:
15 𝑃1
41 𝐺1
15 𝑃2
41 𝐺2
18 𝐵𝑃1
120 𝐵𝑃2
≈ 39/1800
-Gearbox created to mount gears from motor to
Retaining case

17. Drive Train

18. Turner Synchronization
-Lower turning plate is driven by bevel gear
-Upper turning plate is connected by turner
synchros (shown in pink)
-Assembly is held together with set screws
-Plates slide inside grooves of retaining case

19. Spacer Cuff
-This part spaces the whole assembly out
from the arm interface
-This allows the gripper to grip taller parts in
closer to the center

20. Design Drawbacks
-Weight
-May shear objects
-Large width – cannot fit into small spaces
-Can only grip objects up to 80mm in diameter
-Many parts only serviceable if completely
disassembled
-Leave assemblies are 54 mm apart – parts shorter
than this will only be gripped by one leaf assembly.

21. Questions?