Nowadays Robot play a vital role in all the activities in human life including industrial needs. There is a definite trend in the manufacture of robotic arms toward more dexterous devices, more degrees of-Freedom, and capabilities beyond the human arm. The ultimate objective is to save human lives in addition to increasing productivity and quality of high technology work environments. The objective of this project is to design, analysis of a Generic articulated robot Arm. This project deals with the modeling of a special class of single-link articulated inspection arms of robot. These arms consist of flexible massless structures having some masses concentrated at certain points of hollow sections at the beam. Some aspects of the articulated Robot that are anticipated as useful are its small cross section and its projected ability to change elevation and maneuver over obstacle require large joint torque to weight ratios for joint actuation. A knuckle joint actions actuation scheme is described and its implementation is detailed in this project. The parts of the (AIA) arm are analyzed for deflection and stress concentration under loading conditions in different angles.

1. INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 5 ISSUE 1 – MAY 2015 - ISSN: 2349 - 9303
98
Design and Analysis of Articulated Inspection
Arm of Robot
K.Gunasekaran
T.J Institute of Technology, Engineering Design (Mechanical Engineering),
kgunasekaran.25290@gmail.com
Abstract— Nowadays Robot play a vital role in all the activities in human life including industrial needs. There is a definite
trend in the manufacture of robotic arms toward more dexterous devices, more degrees of-Freedom, and capabilities beyond the
human arm. The ultimate objective is to save human lives in addition to increasing productivity and quality of high technology work
environments. The objective of this project is to design, analysis of a Generic articulated robot Arm. This project deals with the
modeling of a special class of single-link articulated inspection arms of robot. These arms consist of flexible massless structures
having some masses concentrated at certain points of hollow sections at the beam. Some aspects of the articulated Robot that are
anticipated as useful are its small cross section and its projected ability to change elevation and maneuver over obstacle require large
joint torque to weight ratios for joint actuation. A knuckle joint actions actuation scheme is described and its implementation is
detailed in this project. The parts of the (AIA) arm are analyzed for deflection and stress concentration under loading conditions in
different angles.
Index Terms— Articulated inspection arm, Articulated robot, Nuclear Power Plant, Prismatic joint
——————————  ——————————
1 INTRODUCTION
At present, the main interest is to protect nuclear
workers in highly contaminated areas with hostile
environmental conditions by the use of robot in nuclear
power plants to reduce human exposure not only to radiation,
but also to hot, humid and oxygen-deficient atmosphere due to
which the research specialist in the field of robotics proposes a
great variety of robot configuration and functional capabilities
to be used in nuclear power plants. The wheeling robot, tracked
vehicles are the most commonly used configuration for mobile
robot.
Fig1. 1 Robotic Design
The present robotic system is made up of mainly three
sub-systems: sensory head; teleportation and control panel and
the inspection mobile robot with vision, sound and also
temperature cover 90% of all inspection tasks required in BWR
nuclear power plants by the method of pan-tilt mechanism. So
that it’s easily plugged in various mechanical inspection robot. A
video camera is used for the purpose of inspection through stereo
vision equipment which are produced by stereo Graphics, has
been integrated in the tele-operation panel.
This stereotype system is greatly used in guiding the
mechanical robot through cloistered areas. The tele-presence is
completed with a stereophonic bi-directional set of audio which
provides signals for sound inspection. To carry out close
inspection tasks of the vacuum vessel first wall using a long
reach robot is called the ―Articulated Inspection Arm‖ of robot
(AIA).
Fig1. 2 Industrial Robot
There is a possible presence of high stresses and high
deformations in bending and torsion in these structures. The load
depends on the articulated structure. The prepared model has got
to be realistic with a good knowledge of the end-effectors
position. The model of the complete robot is the assembly of the
five elementary models are already described before. It provides
the deformation and position of the structure for any given joint
position and loads. The calculation is iterative due to the non-
linearity which are induced by the largely displaced cumulative
effect of the deformations.
1. Classifications of robot
• Cartesian
• Cylindrical
• Polar
• Articulated
A

2. INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 5 ISSUE 1 – MAY 2015 - ISSN: 2349 - 9303
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• SCARA
1.2 Cartesian Robot
Cartesian, or gantry, robot are defined by movement
limited by three prismatic joints. The robot workspace is defined
by a form of rectangular that results in the coincident axes.
Fig1. 3 Cartesian Robot System
1.3 Cylindrical Robot
If one of the Cartesian robot’s prismatic joints is
exchanged for a revolute joint, a cylindrical robot is prepared. Its
movement is defined by a cylindrical coordinate system.
Fig1. 4 Cylindrical Robot System
1.4 Spherical Robot
By trading of two prismatic joints with one revolute
joints a spherical robot is formed.
Spherical, or polar, robot are devices with a polar coordinate
system. It works inside a thick shelled workspace which is in a
spherical form, shown in figure 3.
Fig1. 5 Spherical Robot System
1.5 Articulated Robot
By substituting the revolute joint instead of final
prismatic joint turns the arm into an articulated arm. Any robot
whose arm has at least three rotary joints is considered to be an
articulated robot (figure 4). The workspace is a complex set of
intersecting spheres.
Fig1.6 Articulated Robot System
The above diagram shows the typical articulated robot. The
articulated robot is used to fulfill some special applications. They
lift heavy objects, painting, welding and also handle chemicals,
thereby performing assembly work for days at a time without
even suffering from fatigue as we humans do. Robot is defined
by the nature of their movement.
It can be seen that the required workspace weighs heavily in the
selection of a robotic system.
1.6 SCARA Robot
SCARA (which stands for Selectively Compliant
Articulated Robot Arm) is Specialty robot in which there are two
parallel rotational joints which provide compliance in a plane. A
third prismatic joint allows the arm to translate vertically.
SCARA robot differ from articulated robot in that its workspace
consists of two concentric cylinders, demonstrated in figure 6.

3. INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 5 ISSUE 1 – MAY 2015 - ISSN: 2349 - 9303
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Fig1.7 SCARA Robot System
This robot arm is specialized for assembly operations that involve
placing parts on top of one another. The gripper can raise, lower,
and rotate to orient the component to be assembled.
1.7 Robot Parts
Fig1. 8 Parts of Robotic Arm
Fig1. 9 Work cell Arrangements
1.8 MECHANICAL STRUCTURE
This comprises all of the linkages and joints capable of
movement.
1.9 ACTUATOR TYPES
The necessity for proper selection of actuator will
dictate how effective a robot is in performing a specific task.
Actuators can be either mechanical or electrical and have varying
strengths and weaknesses as demonstrated in table 1. The basic
actuators used for controlling motion include:
• Air Motors
• Hydraulic Motors
• Clutch/Brake
• Stepper Motors
Table 1.2: Actuator Comparison
The most commonly used actuators in robotics consists of
electric motors which can be either a stepper or servo type. The
stepper motor performs well in an open loop systems whereas
servomotors are best suited for applications in a closed loop
system.
2. DESIGN OF EXPERIMENT
2.1 Design of Articulated Inspection Arm (AIA)
The design calculations are formulated from strength of
materials and from the Design of machine elements. The lengths
of the AIAs are calculated considering the distance of the control
panels for the core, the diameter of the core to be inspected and
height of the core. Here the length is considered invariant with
respect to required robot design. The two variants of cross
sections considered are hollow square form and hollow circular
form. Since the electrical and control system wiring to the
various motors in the robotic assembly is subjected to pass
through the hollow portion of the arm so we first consider both
the inner and outer dimensions.
CALCULATIONS
Volume of the shaft, V
V =π/4(do
2
- di
2
) x Length
Considering, k= di /do = 0.75
di = 0.75 do
Volume, V= π/4 (do
2
-0.5625 do
2
) x 4
V=1.37 do
2
m3
-- (1)
Mass of the shaft, m
Mass = volume x density
=1.37do
2
x1.1x103
[
Considering, density of nylon = 1.1x103
kg/m3
]
Mass, m=1507 do
2
-- (2)

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Force Acting On the Shaft, F
Force, f=mass x acceleration due to gravity
=1507 do
2
x 9.81
F= 14783.67 do
2
-- (3)
Power of the motor, P
P = (length of the shaft from the motor
x speed of the motor x load acting)
60
P = 4x 10x14783.67 do
2
/60
P =9855.78 do
2
KW -- (4)
Fig2. 1 Schematic Diagram of the Robot Arm
Bending moment on the shaft occurs due to
1. Motor
2. Camera
3. Knuckle Joint
4. Weight of the shaft
Bending moment, M
=10x4(1+2+3+4+5) + (50x20) +20X2(1+3+5+7+9)
+π/4(do
2
- di
2
) x ρ x 2(1+3+5+7+9)
M = 2600+75350 do
2
-- (5)
Calculations based on Torsion:
Equivalent Torsion,
Te =
Radius of gyration, K = =
=
K = 0.31 do -- (6)
Column Factor, α =
= 1 / 1-0.0044(4/.31do)
= 0.31do/ (0.31do-0.0176) -- (7)
Torque, T = (P x 60) / (2πN)
= (9855.78 do
2
x 60) / 2π x 10
T = 9411.57 do
2
KN-m -- (8)
Te=
=
-- (9)
We also know that,
Te = π/16 x τ do
3
x (1-k4
)
= π/16 x 7.5x109
x do
3
x 0.68
Te = 1.00138 x 109
do
3
KN-m -- (10) Equating
9 & 10, we find that,
do = 0.267 m ≈ 0.27 m
di = 0.75 x 0.27 = 0.202 m ≈ 0.2 m
Calculations based on bending moment:
Me = ½[km x M + + Te
=1/2[1.5 x (2600 + 75350 do
2
) +
+
-- (11)
And,
Me= x σb (do
3
) (1-k4
)
To find σb,
=
J= [do
4
- 0.31do
4
]
J=0.097 do
4
m4
Deflection (y) for nylon material would be 0.07 m for
every 1 m length
y=0.07 m
σb = = 9411.57 do
2
x
σb = 6791.85/ do
2
KN/m2
Me = x (do
3
) (0.683)
Me=455.41do -- (12)
Equating 11 & 12, we get
do = 0.298 m ≈ 0.3 m
di = 0.75 x do = 0.75 x 0.3 = 0.225 m

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2.3. Modeling of AIA
The AIA is modelled using a renowned 3D modeling
software package known as Solidworks. The assembly is
constructed for simulation of the robotic actions during working.
The 3D model is further used for analyzing purpose in ANSYS.
Fig2.2 Exploded view of Assembly AIA
2.2. Analysis of AIA:
Analysis is carried out only for the base arm, since it is the major
arm that handles all the other arms and connects the robot to the
base. The following are the loads considered for analysis on the
arm.
 Force due to the weight of the arms, joints, motors and
camera
 Moment on the joint due to the weight of the arms,
joints, motors and camera
 Torque due to the rotation of torsion motor located on
the wrist of the arm
Fig 2.3 FE model
4. RESULTS AND DISCUSSION
Maximum displacements of hollow circular sections and
rectangular sections consists of 26.638mm and 26.03mm during
the first load step (while considering the position of the base arm
is at 30 degrees). Considering the 4000mm arm length the
deflection is 0.66% in the case of circular and 0.65% in the case
of the rectangular section arm. It cumulates to a maximum of
159.83mm in circular and 156.18mm in rectangular section arm.
It is only an elevated estimate because the bending moment along
with the force acting on the arm will also decrease linearly (5-n)
with the nth
position of the five arms from the base arm. This
deflection is negligible and can be controlled while programming
the controller in more precise method. Therefore, both the
Rectangular and Circular models are eligible for further studies.
Comparison of Displacement sum of circular cross section and
rectangular cross section AIA considering loads when the arm is
at 300
.
Comparison of Von Mises stress of circular cross section and
rectangular cross section AIA considering loads when the arm is

6. INTERNATIONAL JOURNAL FOR TRENDS IN ENGINEERING & TECHNOLOGY
VOLUME 5 ISSUE 1 – MAY 2015 - ISSN: 2349 - 9303
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at 300
4.1 Comparison of Deflection of Circular &
Rectangular C.S of AIA
S. No
Position of
Arm in degree
Deflection in mm
Circular Rectangular
1 30 26.636 26.03
2 40 24.858 24.422
3 50 23.099 22.764
4.2 Comparison of stress distribution in Circular &
Rectangular C.S of AIA
S.No
Position of
Arm in degree
Stress
Circular Rectangular
1 30 4.641 4.345
2 40 4.86 4.331
3 50 4.881 4.318
5. CONCLUSION
The Articulated Inspection Arm of Robot (AIA) is
designed with the use of basic formulae from strength of
materials and from the Design of machine elements. The two
possible hollow cross sections i.e., (Rectangular section and
Circular Sections) is modelled using commercially available 3D
modelling tool known as SolidWorks and they are further studied
and compared.
The models are used for analysis with a commercially
available analysis tool known as ANSYS by taking into account
of various critical loads acting on the base of the robot arm alone.
Since the base of the robot arm is the major component in which
maximum magnitude of the critical loads are expected to occur,
therefore it is enough to analyze the base of the robot arm alone.
Considering the shapes, sizes, deflections during
working and also stress occurs at both the AIAs are workable
comparatively. Considering the manufacture, assembly weight
and ease of transport, the circular section AIAs are preferred over
the rectangular section AIAs.
6. REFERENCE
[1] D. Arthur, Y. Perrot, C. Bidard et al. ITER Articulated
Inspection Arm (AIA), Geometric Calibration Issues of a long –
reach flexible robot. Fusion Engineering and Design75-79(2005)
543-546.
[2] J.V.Miro, A.S.White, Modeling and industrial manipulator a
case study, Simulation practice and theory, 9(2002) 293-319.
[3] Leoncio Briones, Paul Bustmante, Miguel A.Serna, A Wall
Climbing pneumatic robot for inspection in nuclear power plants,
Robotics and computer integrated manufacturing, 0736-
5845(95)00005-4.
[4] O.A.Barbian, W.Kappes, R.Neumann, H.K.Stanger,
apparative developments for in-service inspection of reactor
pressure vessels, Nuclear engineering and design 102(1987)341-
355.
Author Profile:
 K.Gunasekaran is currently pursuing master’s degree program
in Engineering Design in T.J Institute of Technology, Affiliated
to Anna University, India, PH-09629890506.
E-mail:kgunasekaran.25290@gmail.com.