2. Desig
n
Goals
Identification of
need
• Achieve the finishing process efficiently
• Shorten the processingtime
• Ensure the consistencyof processingquality
• Reduce Complexity
• Reduce Maintenance by reducedparts
• Optimized design
8. Design Considerations
Assumptions & Workpiece Specifications
Specifications:-
1. Car considered as model: 2018 Honda Civic
2. Spare tire size: T125/70R17
Assumptions:-
1. Tire is laying flat on the rack
2. General safety always is part of Robotic applications, in case of failure, there is a
safety-fail mechanism
9. Design Considerations
Six Factors
1.Gripping force:
• The gripper must be designed to provide sufficient gripping force to securely hold the spare wheel in place during
installation
• The gripping force required will depend on the weight and size of the spare wheel
2.Gripping mechanism:
• The gripper mechanism must be designed to securely grip the spare wheel without damaging it
• This could involve using a specific type of gripper, such as a pneumatic gripper
3.Size and shape:
• The gripper must be designed to accommodate the size and shape of the spare wheel used in the Honda Civic
10. Design Considerations
Six Factors
4.Compatibility:
• The gripper must be designed to be compatible with the robotic system used for the Honda Civic assembly line
• Involves ensuring that the gripper can be easily integrated into the existing system and that it can be programmed to perform the
required tasks
5.Safety:
• Incorporating safety features such as sensors to detect obstacles or emergency stop mechanisms
• Check valves to Maintain grip ing case of reduced pressure
6. Maintenance and durability:
• Designed to be durable and require minimal maintenance
• This By using materials that are resistant to wear and tear
Standard parts available for replacement
11. Design Considerations
Gripping Force
The gripping force is calculated as the minimum force required to prevent the workpiece from slipping when it is held by fric tion.
𝐹 ≥
𝑚 × 𝑔 × 𝑎
𝑛 × 𝜇
× 𝑆 ≥ 257.512 𝑁
m = 14 Kg
g = 9.81 m/s2
a = 1 m/s2 (Acceleration of robot arm)
n = 2 (number of jaws)
μ = 0.8 (Friction co - efficient steel & Rubber)
S.F = 3 (Factor of Safety)
12. Conceptualization
Bayesian Model
Decision Tree
Problem Structure
• Assessing the probability of successful grasping and insertion based on various design factors such as grip type, gripping
force, and gripper size etc.
• Use problem structuring to identify any potential issues or constraints that may arise during the design process
• These may include limitations on available materials, regulatory requirements for workplace safety, and the need for
compatibility with existing robotic systems in the assembly line
• Use a decision tree to identify the most appropriate gripping mechanism based on the shape and weight distribution of
the spare tire assembly
13. Bayesian
Model
# Factor
Option Desirability Probability
Pneumatic Hydraulic Pneumatic Hydraulic Pneumatic Hydraulic
1
cost of
fabrication
Low High 0.9 0.5 0.6 0.8
2 Assembly Moderate High 0.65 0.9 0.9 0.8
3
Operation
Manual
Moderate High 0.7 0.5 0.5 0.65
4 Safety High Low 0.9 0.6 0.6 0.7
5
Complexity of
parts
Moderate High 0.7 0.6 0.6 0.4
6 Maintenance Low Moderate 0.9 0.75 0.7 0.85
7 Weight Light Heavy 0.7 0.55 0.6 0.7
8
Space area
constraint
Low High 0.8 0.65 0.7 0.7
Normalize Probability 0.1923 0.1786
#
Pneumatic Hydraulic
#
Pneumatic Hydraulic
1 0.1038 0.0714 6 0.1212 0.1138
2 0.1125 0.1286 7 0.0808 0.0688
3 0.0673 0.0580 8 0.1077 0.0813
4 0.1038 0.0750 Total 0.7779 0.6397
5 0.0808 0.0429
16. Synthesis
Parts and material
selection
• Using as many as possible, standard available parts to reduce maintenance cost
• To reduce supply cost, considered only two suppliers for standard parts,
Standard Parts
Material Selection for Customdesigned parts
• Factors were considered such as the application, load requirements, operating conditions, and manufacturing
constraints
• Factors to consider include strength, stiffness, durability, corrosion resistance, and cost
• Material chosen should be able to withstand the expected loads and environmental conditions while meeting the design
requirements and constraints
17. Synthesis
Standard Parts
Using as many as possible, standard available parts to reduce maintenance cost
PneumaticActuator
ISO 15552DoubleActing Cylinder32-80mm
Supplier:Tameson
Weight:2.5 lb./ea.
Material:Aluminum
Rated:
Forcein – Upto 653N
ForceOut– Up to 753 N
18. Synthesis
Standard Parts
Using as many as possible, standard available parts to reduce maintenance cost
Foot Mount
ISO 15552 Stainless steel 316
Supplier: Tameson
Weight: 0.25 lb./ea.
Material: Aluminum
Rated:
Manufacturer recommended for Actuator
19. Synthesis
Standard Parts
Using as many as possible, standard available parts to reduce maintenance cost
MountedLinear Ball Bearing
Self Aligning, for 3/4" Shaft Diameter
Supplier: McMaster-CARR
Size: ¾’’ Diameter
Material: 6061 Aluminum
Rated:
Dynamic Force – 470 lb.
Static Force – 590 lb.
20. Synthesis
Standard Parts
Using as many as possible, standard available parts to reduce maintenance cost
Base-Mounted Shaft Support
for 3/4" Shaft Diameter, Iron
Supplier: McMaster-CARR
Size: ¾’’ Diameter
Material: Cast Iron
21. Synthesis
Standard Parts
Using as many as possible, standard available parts to reduce maintenance cost
Ultra-Straight Tight-Tolerance RotaryShaft
3/4" Diameter, 36" Long
Supplier: McMaster-CARR
Size: ¾’’ Diameter
Material: 1045 Carbon Steel
Rated:
Yield Strength – 50,000 psi
23. Synthesis
Designed Parts
Custom designed parts to meet the unique requirements
Base Plate
16 in X 14.37 in X ½ in
Weight : 5 ¾ lb.
Material : Alloy Stainless Steel
29. Evaluation and Analysis
Forces required by actuator
As derived earlier,
Reaction Force Fg’ = 257.512 N
𝐹𝑝 = 𝐹𝑔′ (neglect friction)
𝐹𝑝 = 257.512 N (two jaw - one side)
30. Evaluation and Analysis
Forces acting on each jaw
As derived earlier,
Actuator Force F = 257.512 N
By balancing forces in x and y directions
We get,
P_x = 224.18 N & Q_x = 33.33N
P_y =179.343 N & Q_y =26.64N
We used these forces to calculate bending moment
and shear stress
31. Evaluation and Analysis
Bending Moment & Shear Force
Yield Strength = 3.45 × 10^8 (1045 carbon steel)
Allowable σ_b = (3.45 × 10^8)/2.5
Allowable σ_b = 138 MPa
35. Evaluation and Analysis
Base Plate Design Optimization
To reduce weight of the base assembly plate
• Non-load bearing parts are cut
• Thickness only ½ in
• High strength and comparatively light-weight, Alloy Steel (SS)
material
• To reduce stress concentration in square corners, fillets are
added
40. Cost Analysis
Bill of Materials
ITEM
NO.
PART NUMBER DESCRIPTION QTY. COST
Total
Amount
1 22345T21 Stainless Steel Ball Stainless Steel
Grease Fitting
1 $510.00 $510.00
2 P2ABJ Actuator Tamson brand 2 $ 94.73 $189.46
3 1440N13 Clamp 4 $ 7.13 $ 28.52
4 9338T3 Mounted Linear Ball Bearing 4 $ 9.92 $279.68
5 1497K12 Sliding Rod Shaft 2 $ 35.67 $ 71.34
6 6068K25 Base-Mounted Shaft Support 4 $ 53.87 $215.48
7 2406N1 Jaw 2 $308.21 $616.42
8 92499A331
18-8 Stainless Steel Male-Female Hex
Thread Adapter
2 $ 14.53 $ 29.06
9 95010A150
Extreme-Strength Steel Extra-Wide
Thin Hex Nut
18 $ 12.58 $226.44
10 22345T6 Robot Connecting Plate 1 $428.13 $428.13
11 6516K382 Connecting Rod 4 $ 5.94 $ 3.76
12 2766N61 Endcaps 4 $ 12.57 $ 50.28
13 90166A148 Hex Bolt 32 $ 9.11 $291.52
14 90710A038 Hex Nut 32 $ 5.43 $173.76
Total
$3,133.85
The cost of the Gripper depends on various factors
• Type of gripper selected
• Materials used
• Labor costs
However, an estimate of the total cost can be made based on
the bill of materials (BOM) and labor costs.
This estimate is parts only.
41. Conclusion
Even tough this gripper is designed based on spare
wheel of Honda Civic 2018
• It can be adjusted to the assembly line of any
car model which has spare tire size of __/__/R14 to
__/__/R20
• Most of the common vehicle’s spare fall in this
range
• Cost and maintenance is low; compare to other
grippers in market
• Whole assembly is symmetric,
Center of gravity is passing through the center of
base plate; this means it avoids the strain caused
by offset geometry;
• It also means the convenience for robot
programmer to set moving path points
