1. Introduction into Computer Aided Design ……………………….. 2 1.1. Computer Aided Design (C.A.D.) ………………………….. …….. [629030]

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Contents
1. Introduction into Computer Aided Design ……………………….. 2
1.1. Computer Aided Design (C.A.D.) ………………………….. ….. 2
1.2. Computer Aided Design in robotics engineering ………….. 5
1.3. Dassault Systèmes CATIA ………………………….. ……………. 7
1.3.1. General information ………………………….. ………………… 7
1.3.2. Facilities ………………………….. ………………………….. ……. 8
2. Project assignment ………………………….. …………………………. 10
3. Designing the pneumatically actuated end effector ………….. 11
3.1. Conceptualisation ………………………….. ………………………. 11
3.1.1. Option A ………………………….. ………………………….. …. 11
3.1.2. Option B ………………………….. ………………………….. …. 12
3.2. Structuralisation ………………………….. ………………………… 13
3.2.1. Option A ………………………….. ………………………….. …. 13
3.2.2. Option B ………………………….. ………………………….. …. 14
3.3. Dimensioning and Motor selection ………………………….. . 15
3.3.1. Pre -Dimensioning ………………………….. …………………. 15
3.3.2. Pneumatic motor selection ………………………….. …….. 17
3.4. Creating the prehensive virtual model ………………………. 19
4. Reference drawings ………………………….. ………………………… 20
Bibliographical references: ………………………….. ………………….. 23

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1. Introduction into Computer Aided Design

1.1. Computer Aided Design (CAD )

The term Computer Aided Design (CAD) involves the use of computers
(otherwise refered to as workstations) to facilitate the accomplishing of various
stages of the design process, namely: creation , analysis, and optimization. CAD
software presents numerous advantages to the field of engineering, such as:
increased productivity on the designer’s part , improved design quality , enhanced
communication with the aid of documentation, and the ability to create a database
for manufacturing. CAD documentation files are mostly generated in an
electronic format f or their use in several manufacturing operations.

Figure 1: Illustrated in the image above is an example of a 2D CAD drawing [1]

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One of the most important advantages of computer aided design , one that
influences as well as defines specific activities throughout a product’s
development process , is facilitating of the acquisition, storage and reuse of all the
previously accumulated information, experimental data, experiences and
knowledge , which can be used for further processing in order to obtain secondary
information. A notable aspect is that this prevents potential error sources and
routine work and generates new databases that can be reused and completed.
These databases incorporate past experiences and product data in a directly
usable fo rm.[4]

Figure 2: Illustrated above is an example of a 3D CAD model [1]

Its use in designing electronic systems is known as electronic design
automation (EDA). In mechanical design it is known as mechanical design
automation (MDA) or computer -aided drafting (CAD), which includes the process
of creating a technical drawing with the use of computer software.[1]

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CAD programs used in mechanical design can employ different graphical
rendering methods: vector -based graphics for the depiction of traditiona lly
drafted objects , or raster graphics showcasing the overall visual appearance of
objects designed in the program . That being said , creating objects in CAD
software is a task which involves more than just drawing shapes. A finished
product designed in a CAD environment must convey information regarding
various technical aspects , such as the product’s materials, the manufacturing
processes, dimensions, as well as tolerances, in accordance with application –
specific conventi ons.

Thus, a CAD program can be used in two ways: it can be used to create
curves and figures in a two-dimensional space, or it can be used to create curves,
surfaces, and solids in a three -dimensional space.
However, it must be mentioned that Computer Aided Design represents
just one specific element of the digital product development (DPD) activity within
the product lifec ycle management (PLM) processes. For that reason, CAD
software must be used in compliance with other tools, which are either integrated
modules or stand -alone products, such as:
 Computer -aided engineering (CAE) and finite element analysis (FEA)
 Computer -aided manufacturing (CAM) including instructions to computer
numerical control (CNC) machin es
 Photorealistic rendering and motion simulation.
 Document management and revision control using product data
management (PDM).

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1.2. Computer Aided Design in robotics engineering

Robotics is becoming a very important part of our lives. The design process
is changing rapidly as the demand increases. As more industries are introducing
robots into their workforce, three dimensional CAD solutions are keeping pace.
Because of this, companies can see what the material is like and use this
knowledge to design the products, while estimating costs.
With 3D CAD software, designers can actually simulate a robot's
capabilities by reviewing how the robot's construction will be effected by the
selected materials.

Figure 3: Exemplified in the image above is a 3D model of a robotic arm
made in CAD software [5]

The next generation of robotic fabrication techniques opens up new
opportunities for design conjecture as well as tackling building performance.

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CAD can be used to design curves and figures in two -dimens ional space ( 2D), or
curves, surfaces, and solids in three -dimensional ( 3D) space.
The designers of robots need powerful software to design their
sophisticated robot systems. This software must be capable of being scalable
across multiple robotics applicat ions and tasks, and be able to incorporate any
existing algorithms. Single software architecture, for both simulation and
implementation, should expedite the design cycle and promote innovative
robotics research to solve problems.
CAM is a subsequent compu ter-aided process after the computer -aided
design (CAD). A model generated in CAD and verified in CAE can be placed into
CAM software, which then controls the machine tool.
The following list contains select examples of Computer Aided Design
software used in various industries:
 Autodesk AutoCAD
 Dassault Systemes CATIA
 Dassault Systemes SolidWorks
 PTC PTC Creo (formerly known as Pro/ENGINEER)
 Siemens NX
 FreeCAD
 SolveSpace
 Alibre Design
Based on market analysis and statistics however, it seems to be apparent
that commercial software from Autodesk, Dassault Systems, Siemens PLM
Software, and PTC dominate the CAD industry.

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1.3. Dassault Systèmes CATIA

1.3.1. General information

The current section of this project will be focused on offering a summary
presentation of both general and functional aspects regarding the CATIA 3D
modelling and simulation software, considering the fact that it represents the
program of choice in realizing the purpo se of this project.

Figure 4: Illustrated in the image above is the logo of the CATIA brand [6]

The CATIA software (the product’s name being an acronym of computer –
aided three -dimensional interactive application) is a multi -platform software suite
for computer -aided design (CAD), computer -aided manufacturing (CAM),
computer -aided engineering (CAE), PLM and 3D, developed by the French
company Dassault Systèmes.
Originally, CATIA started as an in -house development in 1977 by French
aircraft manufacturer AVIONS MARCEL DASSAULT, at that time customer of
the CADAM software to develop Dassault's Mirage fighter jet. It was later
adopted by the aerospace, aut omotive, shipbuilding, and other industries. Initially
named CATI (conception assistée tridimensionnelle interactive – French for
interactive aided three -dimensional design ), it was later renamed CATIA in the

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year 1981 when Dassault created a subsidiary t o develop and sell the software
and signed a non -exclusive distribution agreement with IBM.

Commonly referred to as a 3D Product Lifecycle Management software
suite, CATIA supports multiple stages of product development (CAx), including
conceptualization, design (CAD), engineering (CAE) and manufacturing (CAM).
CATIA facilitates collaborative engineering across disciplines around its
3DEXPERIENCE platform, including surfacing and shape design, electrical, fluid
and electronic systems design, mechanical eng ineering and systems engineering.
CATIA facilitates the design of electronic, electrical, and distributed
systems such as fluid and HVAC systems, all the way to the production of
documentation for manufacturing.

1.3.2. Facilities

CATIA enables the crea tion of 3D parts, from 2D sketches, sheetmetal,
composites, molded, forged or tooling parts up to the definition of mechanical
assemblies. The software provides advanced technol ogies for mechanical
surfacing and BIW. It provides tools to complete product d efinition, including
functional tolerances as well as kinematics definition. CATIA provides a wide
range of applications for tooling design, for both generic tooling and mold and
die. In the case of Aerospace engineering an additional module named the
aerospace sheetmetal design offers the user combine the capabilities of generative
sheetmetal design and generative surface design .
CATIA offers a solution to shape design, styling, surfacing workflow and
visualization to create, modify, and validate complex innovative shapes from
industrial design to Class -A surfacing with the ICEM surfacing technologies.
CATIA supports multiple stages of product design whether started from scratch
or from 2D sketches (blueprints).

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The CATIA Systems Engi neering solution delivers a unique open and
extensible systems engineering development platform that fully integrates the
cross -discipline modeling, simulation, verification and business process support
needed for developing complex ‘cyber -physical’ produc ts. It enables organizations
to evaluate requests for changes or develop new products or system variants
utilizing a unified performance based systems engineering approach.
CATIA v 5 offers a solution to formulate the design and manufacturing of
electrical systems spanning the complete process from conceptual design through
to manufacturing. Capabilities include requirements capture, electrical schematic
definition, interactive 3D routing of both wire harnesses and industrial cable
solutions through to the production of detailed manufacturing documents
including form boards.
CATIA v 5 offers a solution to facilitate the design and manufacturing of
routed systems including tubing , piping, Heating, Ventilating and Air
Conditioning (HVAC). Capabilities include requirements capture, 2D diagrams
for defining hydraulic, pneumatic and HVAC systems, as well as Piping and
Instrumentation Diagram (P&ID). Powerful capabilities are provided that enables
these 2D diagrams to be used to drive the interactive 3D routing and placing of
system components, in the context of the digital mockup of the complete product
or process plant, through to the delivery of manufacturing information including
reports and piping isometric drawings.

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2. Project assignment

The objective of this project is to design a functional pneumatically actuated
end effector (or gripper) with the purpose of manipulating a cylindrical piese with
the specified dimensions illustrated in Figure 5 bellow the current paragraph. The
cylindrical piese as well as the structural components constituting the pneumatic
gripper must be made of steel.

(Figure 5: Illustrated in the image above is the sized cylindrical piese)

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3. Designing the pneumatically actuated end
effector

3.1. Conceptualisation

The opening phase in the design process of the project’s pneumatic gripper
involves the drawing of kinematic diagrams for two basic potential solutions in
the CAD program of choice. The following diagrams have been created using the
CATIA Drafting Workbenc h.

3.1.1. Option A

(Figure 6: The image above represents the kinematic diagram for the first gripper
solution)

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As can be observed previously in Figure 6 of the first solution , the
pneumatic linear drive actuates the sliding kinematic element 1 which executes a
translational motion through the base marked as 0. While that is happening, the
passive element 3 (connected to both mobile element 2 through joint B as wel l as
mobile element 1 through joint C) allows the mobile element 2 to execute a
pivoting movement around joint A and effectively grasp the cylindrical piese.

3.1.2. Option B

(Figure 7: The image above represents the kinematic diagram for the second
gripper solution)

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In the kinematic diagram presented in figure 7, element 3 executes a
translational movement via the cylinder of the linear pneumatic motor. While this
action is being executed, the conrod -type passive element marked as 1 transmits
movement to mobile element 2 via joint B. Element 2 makes a pivoting movement
thanks to its connection to joint C, thus grasping the target object.

3.2. Structuralisation

This following step of the project involves creating 2D constructive
drawings for the two basic solutions from the previous subchapter in the CAD
software of choice. If the purpose of the kinematic diagrams from the first stage
was to explain the operating principle of the two potential pneumatic grippers,
these drawings’ purpose is to illustrate the construction and the assembly of the
various components that form the pneumatic grippers. The following drawings
have been created using the CATIA Drafting Workbench.

3.2.1. Option A

(Figure 8: The image above represents the constructive structure of the
first gripper solution)

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3.2.2. Option B

(Figure 9: The image above represents the constructive structure of the
second gripper solution)
Observation: In both solutions’ cases one of the prisms is designed with a
flat surface in order to ensure a grasping and positioning that benefit from
increased precision as well as stability. This design can be seen in figures 8 and 9
at the end of the two gripper s’ lower arm s.
For the remainder of the proj ect, the gripper solution to receive further
development will be Option A.

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3.3. Dimensioning and Motor selection

This present phase of the designing process will be focused on pre –
dimensioning the constructive elements of the pneumatically actuated gripp er. It
is important that the constructive elements are dimensioned so that they are
directly proportional to the cylindrical piece that is to be manipulated. Also, after
the dimensioning is finished and the workpiece’s weight as well as the pneumatic
gripp er’s stroke are determined, a linear pneumatically driven motor must be
selected to actuate the system.

3.3.1. Pre -Dimensioning

(Figure 10 : The image above illustrates the gripper’s pre -dimensioned
constructive elements)

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The purpose of the constructive elements’ pre -dimensioning is to determine
the necessary stroke of the pneumatically actuated gripper. For the current
project, a 20 mm stroke will suffice. After determining the stroke the focus is
shifted towards the workpiece and its weight . The image shown in figure 10 was
created in the CATIA Sketcher.

(Figure 11: The image above illustrates the workpiece’s various physical
characteristics)
Of all the physical characteristics obtained using the inertia measurement
tool the most relevant is the cylindrical piece’s mass. As can be noticed in Figure
11, the workpiece has a mass of 141 grams. With the help of this in formation we
can calculate the workpiece’s weight using the following equation:

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In the equation visible on the previous page, W represents the weight of the
workpiece measured in Newtons, m represents the mass of the workpiece
measured in grams, and g represents the acceleration of gravity. Thus we have:

3.3.2. Pneumatic motor selection

Now that all of the necessary values have been determined, a linear
pneumatically driven motor must be selected for the system to properly function.
Taking into consideration the e nd effector’s stroke, its construction and the
workpiece’s weight and dimensions, I have decided to use a model DSBC -32-20-
PPVA -N3 pneumatically actuated piston rod cylinder manufactured by the
german Festo multinational industrial control and automation company .

(Figure 12: The image above displays the Festo linear pneumatically driven
motor chosen to actuate the system)

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A few of the pneumatic motor’s basic features are the following:
Function Double -acting
Piston diameter 32
Stroke 20
Cushioning Pneumatic cushioning
Position sensing For proximity sensor
Profile type Sensor slots on one profile only

Other select features that the chosen pneumatic motor benefits from are:
 Self-adjusting pneumatic end -position cushioning which adapts optimally
to changes in load and speed
 Standard profile with two sensor slots
 Wide range of variants for customized applications
 Comprehensive range of mounting accessories for just about every type of
installation
 Magnetic piston for position sensing

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3.4. Creating the prehensive virtual model

The objective of this current chapter is to design the 3D virtual model of
the pneumatically actuated gripper using the CAD program of choice. As with the
previous chapters, the virtual model of the pneumatic end effector is created in
Dassault Systemes CATIA V5 R19.

(Figure 13: The image above represents the 3D prehensive virtual model of
the pneumatically actuated gripper)

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4. Reference drawings

Now that the virtual model of the pneumatic end effector has been finished,
the final step of the project involves generating 2D reference drawings of the
gripper in order to properly showcase the various dimensions of the constructive
elements as well as the complete assembly. For this chapter, three drawings must
be generated: one overall drawing of the mechatronic device as well as the
execution drawings for tho of the end effector’s constructive elements. The
following drawings are generated in CATIA Dr afting Workbench.
(Figure 14: The image above illustrates the assembly layout of the pneumatic
gripper, featuring the device’s overall dimensions)

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Observation: The P.A.G. designation for various components of the end
effector visible in Figure 14’s bill of materials stands for „Pneumatically Actuated
Gripper” -P.A.G. Also the assembly is displayed with the cylindrical workpiece in
its grasp.
The assembly drawing on the previous page showcases two views of the
pneumatically actuated gripper: in the lower part of the image there is the
isometric view of the gripper while in the upper part of the image there is a
section view of the system.

(Figure 15: The image above illustrates the execution drawing for the
pneumatic gripper’s shaft designated P.A.G. 0-04)

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(Figure 16: The image above represents the execution drawing for the
pneumatic gripper’s secondary body designated P.A.G. 0-09)

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Bibliographical references :

[1] https://en.wikipedia.org/wiki/Computer -aided_design
[2] https://www.roboticstomorrow.com/article/2014/08/digital –
design -using -cadcam -for-innovative -robotic -design/4518/
www.pneumatictips.com
[4] Mircea Teodor P op, CAD FOR MECHATRONICS Course
[5] https://www.cadcam.org/blog/robotics -design -using -cad/
[6] https://en.wikipedia.org/wiki/CATIA
[7] CAD software Dassault Systèmes CATIA V 5R19