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1
CHAPTER- 1
1. INTRODUCTION
In the broadest sense of the world, unmanned systems are a group of
military systems, their common characteristic being the fact that there is no
human operated aboard. They may be mobile or stationary. They include
categories of “Unmanned Ground Vehicles (UGV), Unmanned Aerial
Vehicles (UAV), Unmanned Underwater Vehicles (UUWV), Unattended
Munitions, and unattended Ground Sensors”. Missiles, rockets and their sub
munitions, and artillery are not considered unmanned systems.
The unmanned ground vehicle is a powered, mobile, ground
conveyance that does not have a human aboard. It can be operated in one or
more modes of control (autonomous, semi- autonomous, tele-operation,
remote control). It can be expendable or recoverable. It can have lethal or
nonlethal mission modules.
Functions of Unmanned Ground Vehicle:
Remote Controlled by operator via line-of-sight and via forward-
looking camera and sensors.
Auto Navigation
Detect obstacles and avoid them. Navigate and see depression
in known terrain without losing stability. Navigate tight passages (water,
bushes, concrete wall, etc…) by sensing environment. Choose navigation
options through a local intelligent path planner. Know its pose and navigate
day/night in all-weather condition. Know position within a perimeter with
respect to other items in the environment.
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Behavior
Perform patrol continuously without human intervention. Pass
through and coordinate access to a constricted portal. Monitor
potential threats at a strategic observation point. Listen and
communicate with intruder.
Collaboration
Execute missions with other UGV’s. Re plan missions based on
the loss or addition of team members. Reason and reactively plan in
continuously changing environment. Autonomously navigate, patrol
and protect a known perimeter with collaboration.
History of Unmanned Ground Vehicle:
The development of autonomous robots began as an interesting
application domain for artificial intelligence researches in the late
1960s.
The first major mobile robot development effort was SHAKEY
developed in the late 1960s to serve as a test bed for DARPA-founded
artificial intelligence. SHAKEY was a wheeled platform equipped
with steerable TV camera, ultrasonic range finder, and touch sensors,
connected via an RF link its mainframe computer that performed
navigation and exploration tasks. The SHAKEY system could accept
English sentence commands from the terminal operator, directing the
robot to push large wooden blocks around in its lab environment
“world”. The action routines took care of simple moving, turning, and
route planning. The programs could make and execute plans to
achieve goals given to it by a user.
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Fig-1.1
The SHAKEY program reemerged in the early1980s as the DARPA
Autonomous Land Vehicle (ALV).3 Under DARPA’s Strategic Computing
(SC) Program. The Autonomous Land Vehicle was built on a Standard
manufacturing eight-wheel hydrostatically-driven all-terrain vehicle capable
of speeds of up to 45 mph on the highway and up to 18 mph on rough
terrain. The ALV could carry six full racks of electronic equipment in dust-
free air conditioned comfort, providing power from its 12-kW diesel power
unit. The initial sensor suite consisted of a color video camera and a laser
scanner from the Environmental Research Institute of Michigan. The ALV
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Program’s focus was moved in early 1988 away from integrated
demonstrations of military applications and toward the support of specific
scientific experiments for off-road navigation.
The Reconnaissance, Surveillance and Target Acquisition (RSTA)
application has long drawn the attention of UGV developers, since a UGV
solution for RSTA would provide a battlefield commander with a direct
sensing capability on the battlefield and even behind enemy lines, without
endangering human personnel. Two RSTA-oriented UGV projects were
undertaken at the Naval Ocean Systems Center (NOSC) in the early1980s:
the Ground Surveillance Robot (GSR) at NOSC San Diego, and the
Advanced Tele-operator Technology (ATT) Tele-Operated Dune Buggy at
NOSC Hawaii.4The Ground Surveillance Robot project explored the
development of a modular, flexible distributed architecture for the
integration and control of complex robotic systems, using a fully actuated 7-
ton M-114 armored personnel carrier as the test bed host vehicle. With an
array of fixed and steerable ultrasonic sensors and a distributed blackboard
architecture implemented on multiple PCs, the vehicle successfully
demonstrated autonomous following of both a lead vehicle and a walking
human in1986 before funding limitations terminated its development.
The Advanced Tele-operator Technology Tele-Operated Dune Buggy,
on the other hand, concentrated exclusively on tele-operator control
methodology and on “advanced, spatially-correspondent multi-sensory
human/machine interfaces.” With a Chenowth dune buggy as a test bed
vehicle, the Advanced Tele-operator Technology project successfully
demonstrated the feasibility of utilizing a remotely operated ground vehicle
to transit complex natural terrain and of remotely operating vehicle-mounted
weapons systems. In addition, the Advanced Tele-operator Technology
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effort demonstrated the efficacy of stereo head-coupled visual display
systems, binaural audio feedback, and isomorphic vehicle controls for high-
speed remote vehicle operations.
Fig 1.2
The success of the Advanced Tele-operator Technology and Ground
Surveillance Robot vehicles led the Office of the Undersecretary of Defense
for Tactical Warfare Programs/Land Warfare (OUSD/TWP/LW) in 1985 to
initiate the Ground/Air Tele-Robotic Systems (GATERS) program, under
Marine Corps management and with NOSC serving as the developing
laboratory. The thrust of the GATERS program was to develop a Tele-
Operated Vehicle (TOV) to support the test and evaluation of UGV product
concepts by prospective military users of UGVs. The TOV system consisted
of a remote vehicle and an operator control station, connected by fiber optic
cable to provide high bandwidth secure non-line-of-sight communications
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for distances up to30 km. The TOV remote vehicle was a HMMWV, and up
to three TOV control stations were housed in a shelter mounted on the back
of another HMMWV. Building on the dune buggy experience, the TOV
operator was provided with stereo head-coupled visual displays, binaural
audio and driving controls isomorphic to those found in an actual HMMWV.
A RSTA package (video and FLIR cameras and an active laser range
finder/designator) was mounted on a pan/tilt unit atop a scissors lift that
could be raised up to 15 feet off the ground. High level control architecture
was implemented to integrate the functionality of the system. Successful
demonstrations of the TOV began at Camp Pendleton in May 1988,
including long range RSTA, high-speed cross country transit, detection of
chemical agents, and remote firing of a 50-caliber machine gun.
The weapon could be manually controlled with the joystick in
response to video from this camera, or slaved to the more sophisticated
electro-optical sensors of the Surveillance Module. One of the remote
HMMWVs had a Hellfire missile launcher instead of a Surveillance Module,
the idea being that one platform looked and designated while the other did
the shooting. Meanwhile, all the humans could be up to15 kilometers away,
which is important in chemical or biological warfare scenarios. These
successful demonstrations led to the formulation of the Tele-operated Mobile
Anti-Armor Platform (TMAP) program, and prototype systems were
procured in1987/1988 from Grumman and Martin Marietta. Both systems
were joystick-controlled via fiber optic link, the operator navigating via the
returned TV image.
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CHAPTER – 2
LITERATURE SURVEY
We have referred to the following journals,
1. The journal “Experiences in Developing a Tactical Unmanned
Ground Vehicle for First Responders” published in NAIT (Northern
Alberta Institute of Technology) by professors Mark Archibald, David
Carpenter and Daniel Racette, was based on an historical account of the
strategies developed and the challenges experienced by the Northern Alberta
Institute of Technology (NAIT) Robotics Research Team as they developed
a prototype unmanned ground vehicle for use by Police, Fire and Rescue
Services. Development of performance characteristics for the vehicle, driven
by operational experience and needs of end users in the Edmonton Police
Service (EPS) and the local RCMP division were described.
Discussion continued with consideration of performance, complexity and
cost tradeoffs associated with various electromechanical drive systems,
arriving at the selection and implementation of a chain-free multi-motor
drive system.
The paper described those developments and outcomes in detail.
Deployment of a wide-angle camera via an “off the shelf” 2.5 m extending
mast system were briefly introduced. The paper concludes with discussion of
near term development goals for that project.
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2. Research on U.G.V were done in Fraunhofer Institute for
Intelligent Analysis and Information System (IAIS) and University of
Applied Sciences Bonn-Rhein-Sieg, St. Augustin, Germany .proffesors
Hartmut surmann, Dirk Holz , Sebastian Blumenthal , Thorsten linder ,
Peter Molotor and Viatcheslav Tretyakov published the journal “Tele-
operated Visual Inspection and Surveillance with Unmanned
Ground and Aerial Vehicles”This paper introduced a robotic system named
UGAV (Unmanned Ground Vehicle) consisting of two semi-autonomous
robot platforms, an Unmanned Ground Vehicle (UGV) and an Unmanned
Aerial vehicles (UAV). The paper focused on three topics of the inspection
with the combined UGV and UAV : (A) tele-operated control by means of
cell or smart phones with a new concept of automatic configuration of the
smart phone for the vehicles control capabilities, (B) the camera and vision
system with the focus to real time feature extraction e.g. for the tracking of
t(C) the architecture and hardware of the UAV.
3. The journal ”Elementary Mechanical Analysis of Obstacle
Crossing for Wheeled Vehicles” published by professors Matthew
D.Berkemeier, Eric Paulson, and Travis Groethe describes a model of a
wheeled ugv in an elementary manner to determine the effect of obstacle
height on makor design parameters, such and wheel size, wheelbase, and
center of mass height. The parer consider both static and dynamic modeling
approaches and find that consideration of dynamics allows for more freedom
in parameter choice.
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4. The journal” Design and Simulation Research on a New Type of
Suspension for Lunar Rover” by CHEN Bai-Chao, WANG Rong-ben,
YANG Lu, JIN Li-sheng, GUO Lie proposed a new type of suspension for
lunar rover. The suspension was mainly constructed by a positive
quadrilateral levers mechanism and a negative quadrilateral levers
mechanism. The suspension was designed based on following factors:
climbing up obstacles, adapting terrain, traveling smoothly, and distributing
equally the load of cap to wheels. In that article, firstly the structure of the
new suspension was described, secondly the kinematics of the levers was
analyzed, and the relational equations of the suspension levers were
established, so the distortion capability of the suspension was known. In
order to test the capability of suspension, they designed a prototype rover
with the new suspension and took a test for climbing obstacles, and the result
indicated that the prototype rover with the new type of suspension had
excellent capabilities to climb up obstacles with keeping cab smooth. Based
on the shortcoming found in test, they optimized levers mechanism and then
established the rover models with the new type of suspension system.
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CHAPTER-3
SPECIFICATION AND CALCULATION
3.1 SPECIFICATION OF THE VEHICLE:
Weight of the vehicle : 40kg
Maximum weight of payload
which the vehicle can carry : 20 kg
Speed range of the vehicle : 1 km/hr – 20km/hr
Steering mechanism : By relative motion of wheels.
No of wheels used : 4
Tractive effort generation : 4 wheel drive
Braking system : cam actuated by motor
Main tool : surveillance by 360 °
rotatable camera.
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3.2 CALCULATION
3.2.1 Power Required for Motor:
Total load = Pay load + weight of the vehicle
= (20 + 40) kg
= 60 kg
Diameter of the wheel = 300 mm
Coefficient of friction (µ) = 0.5
Tractive effort = (Total load) × (Coefficient of friction)
= 60 kg × 0.5
= 30 kg
= 300 N
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Torque = Load × perpendicular distance
= 300N×0.15m
= 45 N-m
Speed Required = 20 km/hr.
= 333.33 m/min
Distance Travelled in one revolution
= × (diameter of the wheel)
= × 0.3m
= 0.94 m
Required RPM = 333.33 / 0.94
= 355 RPM
Overall Power required (P) = (2×π×N×T) / 60
= 1600 watts
Power required for individual motor
= 1600 watts / 4(no of motor used)
= 400 watts
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3.2.2 BRAKING CALCULATION:
Braking energy = Loss of kinetic energy of vehicle.
Initial kinetic energy = Energy at maximum speed of the vehicle.
Final kinetic energy = 0
Energy lost =(Initial – Final) kinetic energy
=1 / 2 mvmax2 - 0
Work done by brake = (Ft × πd × N × t)
Ft - Tangential force
d - Diameter
N - rpm
t - Time period of brake.
{By law of conservation of
Energy} : Energy lost = work done by braking system
½ m vmax2 = (Ft × πd × N × t)
Substituting the values
1×60×5.52
= Ft × π × 5×103 ×350×t
t - Time period of brake.
Deceleration (d) = 0.3 × g
g - Acceleration Due to Gravity
= 0.3×9.8
= 2.94 m/s2
t = v/d
v – Velocity of the vehicle, m/s
d – Deceleration, m/s2
t= 5.5 / 2.94
t= 1.9 s
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{Substituting the value of t
in main equation Ft} = 90.06 N
Fig 3.1
1. The angle of contact of the frictional surface to the shaft is more
than 60° and
2. The line of action of tangential braking force is offset by a distance
“a” above the hinged joint of braking lever
then by resolving the forces and taking moments about the point “o”
(Rn × x) = (p × l) + (Ft × a)
Rn - Normal reaction force due to application
of brake
l - Length of braking lever, m
p - Load required for braking, N
x - Distance from hinged joint to center of
frictional surface, m
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a - Offset distance, m
= (4 sin Ɵ) / (2 Ɵ + sin 2 Ɵ)
µ -actual coefficient of friction - 0.3
-altered coefficient of friction
Ɵ - Angle of contact
= (4×0.3×sin 90) / (Π + sin 180)
= 0.38
R n = (Ft / )
(Ft × x) / = (p × l) + (Ft × a)
Ft = 90.06 N
x = 0.115 m
l = 0.18 m
a = 0.0172 m
Substituting the value in main equation
(90.06 × 0.115) / (0.38) = (P × 0.18) + (90.06 × 0.0172)
Hence, Braking Load (P) = 142.8 N
{Braking load required
for each wheel} = P/4 (no of wheels)
= 142.8 / 4
= 35.7 N
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3.2.3 WEIGHT CALCULATION:
Weight of frame
= 0.970 kg / m
Total Length of frame = (0.7 + 0.7 + 0.41 + 0.41)
= 2.22 m
Therefore weight = 0.97 × 2.22
= 2.15 kg
Weight of Battery
= 1.5 × 8 (No of batteries used)
= 12 kg
Weight of Motor
= 1.1 × 4 (No of motors used)
= 4.4 kg
Weight of Sheet Metal
Volume of sheet metal = Length × Breadth × Thickness
Volume of sheet metal = 0.9 × 0.5 × 0.005
= 0.00225 m3
Density of aluminium = 2700 kg / m3
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Therefore Weight = Volume × Density
= 0.00225 × 2700
= 6.075 kg
Weight of Wheel
= 2 × 4 (no of wheels)
= 8 kg
Weight of Transmission Shaft
= Volume × Density
Volume = ((π / 4) × d2) × l)
d -Diameter of Shaft, m
l - Length of Shaft, m
Density of M.S = 7830 kg / m3
= {((π / 4) × d2) × l × density} × (No of
shafts)
= π / 4 × 0.022 × 0.11 × 7830 × 4
= 1.1 kg
Weight of L-Clamp
Volume × Density
Volume = Length × Breadth × Thickness
= 0.125 × 0.02 × 0.003
= 0.0000075 m3
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Density = 7830 kg / m3
= 0.0000075 × 7830
Therefore Weight = 0.0587 × 27 (no of L-Clamps)
= 1.58 k
Weight of braking motor
= 0.3 × 4 (no of motors)
= 1.2 kg
Weight of braking lever
Volume × Density
Volume = Length × Breadth × Thickness
=0.185 × 0.005 × 0.005
= 0.00000463 m3
Density = 7830 kg / m3
Therefore = 0.00000463 × 7830 × 4 (no of levers)
= 0.145 kg
Weight of body
= 1.5 kg
Weight Of camera
= 0.3 kg
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Miscellaneous Weight
= {Weight of (Lock nut + Nut and Bolts +
sensors + Allen Keys +
Battery and Camera casing}
= 2 kg
3.2.3.1 WEIGHT CALCULATION TABLE:
S.NO PARTS WEIGHT (kg)
1 Frame 2.15
2 Battery 12
3 Motor 4.4
4 Sheet metal 6.075
5 Wheel 8
6 Transmission Shaft 1.1
7 L-Clamp 1.58
8 Braking Motor 1.2
9 Braking Lever 0.145
10 Body 1.5
11 Camera 0.3
12 Miscellaneous Weight 2
TOTAL WEIGHT 41.28
Table 1.1
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3.2.4 SHAFT CALCULATION:
Power Transmitted by shaft = 400W
Power = (2 × π× N× T max) / (60)
N - rpm
T max - Torque
RPM of shaft = 350
T max = (400×60) / (2×π×60)
= 10.91×10 3
N-mm
T max =π/16 × τ × d3
τ - Allowable shear stress of M.S
= 200 N/mm2
d - Diameter of the Shaft
= 20mm
T max = π/16 × ×203
Equating the value of T max
= 10.91×103 = π/16 × ×20
3
actual = 6.95 N/ mm2
21
(Multiplying with factor of safety (2) = 13.9 N/mm2
Since actual is less than allowable shear stress the design is safe.
SHAFT SUBJECTED TO BENDING ONLY:
Bending Moment (M) = W × L
W - Load
L - Length
= 150×150
= 22500 N-mm
Bending Moment (M) = (π/32) × σ b × d3
σ b - Tensile Stress
= 400Mpa
= 400 N/mm2
Equating the values of moments
22500 = π/32 × × 20
3
Actual =28.66N/mm2
Multiplying with factor of safety (2) = 57.32 N/mm2
Since actual bending stress is less than tensile strength of mild steel the
design is safe.
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SHAFT SUBJECTED TO COMBINED TWISTING AND BENDING:
Max shear stress theory:
T e = √ (T2+M
2)
T e - Equivalent Torque
M - Bending Moment
T - Torque
= √ (10.91×103)
2 + (22.5×10
3)
2)
= 25× 103
Nmm
Equating Value of Torque
25×103
= π/16 × ×203
Actual =15.92
Multiplying with factor of safety 2 = 31.85N/mm2
Since combined stresses is less than shear strength of mild steel the design is
safe by Max shear stress theory.
NORMAL STRESS THEORY:
Equivalent Bending moment (Mt) = ½(M + √ (M2 + T
2))
= ½(M + T e)
Te - Equivalent Torque , Nmm
M - Bending Moment, Nmm
= (22.5+25) × 103
Nmm
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Mt =23.75×103
N-mm
(Equating the values of
bending moment )
23.75×103
= (π/32) × × 203
actual = 30.25 N/mm2
Multiplying with factor of safety (2) =60.5 N/mm2
Since combined stresses are less than yield strength of mild steel the design
is safe by normal stress theory.
3.3.5 STRENGTH OF SHEET METAL:
Load acting on sheet metal = weight of battery
= 12 kg
=120 N
Considering the sheet metal as simply supported beam
Bending stress = M / Z
M - Bending moment, Nmm
Z - Section modulus, mm3
M= ((W × L2)
/ 8)
W -Load per Unit Area, N/mm2
L - Load acting span, mm
24
W=120N/ (160×125)
=6 × 10-3
N/mm2
L =160 mm
M = {((6×10-3
) ×1602) / 8}
=19.2 Nmm
Z = (b × d2)
/ 6
b - Width of the beam, mm
d - Thickness of the beam, mm
b = 125 mm
d = 5 mm
Z= (125×52) / 6
= 520.83mm3
Substituting the value of M and Z in the main equation
= 19.2 / 520.83
= .0369 N/mm2
= 36905 N/m2
Modulus of elasticity of aluminium is 0.579 × 105 N/mm
2
Since the bending stress formed due to the load is less than modulus of
elasticity of aluminium the design is safe.
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3.4 MATERIAL PROPERTIES:
3.4.1 Carbon steel casting subjected to pressure and high temperature
Chemical composition %:
C Si Mn S P
0.25 0.6 0.7 0.05 0.05
Yield Strength – 210 N/mm2
Ultimate tensile strength – 420 N/mm2
Elongation – 20%
Impact Value (charpy) – 25 Nm
3.4.2 Aluminium Alloy HS 1060 H12:
Chemical composition: Si=0.25%, Fe=0.35%, Al = 99.6% min
Yield strength - 28 Mpa
Tensile Strength - 69 Mpa
Modulus of Elasticity - 57 Gpa
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CHAPTER- 4
STRESS ANALYSIS
4.1 PROCEDURE:
The anlysis report is done using ANSYS 11.0
Initially set the working directory performance and then select
structural.
GOTO PREPROCESSOR
Element Type Add/Edit/Delete
Select, Solid Quad 4 Node 42
Option K3
Plane Stress with Thickness
Close
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Real Constrain Add/Edit/Delete
Thickness 2D
Close
Material Properties Material Mode
Structural
Linear
Elastic
Isotropic (2×105, 0.32)
Close
Modeling Create
Area
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By center and corner
[x=0, y=0, w=500, h=900, t=5]
Ok
Operate
Boolean
Area
Ok
Meshing Mesh Tool
Area set
Pick area (element size=4
29
Ok
Mesh Pick surface
Apply
Solution Defined load
Apply
Displacement
On lines
Pick lines
Apply
All DOF Ok
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Pressure On lines Apply F= 7.5 N Ok
Solution Solve
Current LS Ok
General Post Processor Read Result
Last set
Plot Result
Contour Plot
Nodal solution
Stress Von miss stress
Ok
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4.1.1 STRESS ANALYSIS REPORT:
Since the stress formed from the analysis is less than the yield strength of
aluminium, hence the design is safe.
Fig 4.1
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4.1.2 STRESS ANALYSIS OF SHAFT:
Since the maximum shear stress formed from the analysis is less than the
modulus of elasticity of mild steel, hence the design is safe.
Fig 4.2
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CHAPTER- 5
PARTS DESCRIPTION AND SUB-ASSEMBLIES
5.1 FRAME ASSEMBLY
5.2 GEARED BRUSHLESS DC-MOTOR ASSEMBLY
5.3 BATTERY ASSEMBLY
5.4 WHEEL ASSEMBLY
5.5 BRAKE ASSEMBLY
5.6 CAMERA ASSEMBLY
5.7 BODY ASSEMBLY
5.8 MICROCONTROLLER
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5.1 FRAME ASSEMBLY:
Frame is made up of aluminium alloy. Aluminium is used
because of its less weight.
There are 4 frames used. The 4 frames are joined using 4 L-
clamps with the help of bolts and nuts.
The frame is fixed with clamps and bolts rather than welding
because clamping is stronger when compared to welding. Moreover
welding an aluminium material is more costly.
5.1.1 FRAME
Fig 5.1.1
35
5.1.2 CLAMP:
Fig 5.1.2
36
5.1.3 SHEET METAL:
The sheet metal is clamped above the frame using screws. The sheet
metal is used to hold the following parts
Geared motor
Batteries
Microcontroller
Camera
The thickness of the sheet metal used is 5 mm. With the help of Ansys
11.0 it is been proved that 5 mm thickness sheet is capable of holding all the
mentioned things.
There are many holes in the sheet metal for holding the motors
batteries etc. The mountings of the batteries, motors etc are done by
assuming the center of gravity at the center.
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Fig 5.1.3
38
5.1.4 SUB-ASSEMBLY PROCEDURE:
The four frames are arranged in a rectangular manner and are fastened
by L-clamps and bolts and nuts. The sheet metal is placed over the frame and
fastened by bolts and nuts.
5.1.4.1 EXPLODED VIEW:
Fig 5.1.4
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5.2 GEARED BRUSHLESS DC-MOTORS-ASSEMBLY
There are 4 brushless DC geared motors used. The motors are the
prime movers. They give the movement to the wheels and hence mobility of
the vehicle is taken care by the motors. The following are the ratings of the
motors used,
24 volts
16.66 amperes
Gear reduction ratio is 8:1
5.2.1 GEAR BOX:
Fig 5.2.1
40
5.2.2 BRUSHLESS DC-MOTOR:
Fig 5.2.2
41
5.2.3 CLAMP:
Fig 5.2.3
42
5.2.4 EXPLODED VIEW:
Fig 5.2.4
43
5.3 BATTERY-ASSEMBLY:
Battery is the main power house of the UGV. This supplies the required
power for the functioning of motors, sensors, camera etc. The battery used is
lead acid batteries. They are 8 in numbers. The batteries are divided into 2
groups consisting 4 batteries each. These batteries are held in a casing.
The specifications of the batteries are,
Weight of the batteries - 12Kg
Voltage - 12v
Ampere - 7 amps/ hr
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5.3.1 BATTERY:
Fig 5.3.1
45
5.3.2 BATTERY CASING:
Fig 5.3.2
46
5.3.3 CLAMP:
Fig 5.3.3
47
5.3.4 SUB-ASSEMBLY PROCEDURE:
Four batteries are arranged in order and are placed inside the
casing compactly.
The casing is welded with l-clamp.
This assembly is in turn fastened through the sheet metal by nut
and bolts.
A similar setup is done for another four batteries on the other
half of the vehicle with the same distance from the center in
order to retain the C.G at center.
5.3.4.1 EXPLODED VIEW
Fig 5.3.4
48
5.4 WHEEL ASSEMBLY:
There are 4 wheels used. They are the most essential part of the
vehicle as they help the UGV to move to places. The wheels used here are
meant for normal terrain. The wheels are made up of n-butyl rubber.
The specifications of the wheels are,
Diameter of the wheel is 300mm
The hub diameter is 24mm
The width of the wheel is 93.5 mm
The weight of the wheels- 2 kg
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5.4.1 RIM:
Fig 5.4.1
50
5.4.2 TYRE:
Fig 5.4.2
51
5.4.3 TRANSMISSION SHAFT AND LOCK-NUT:
The shaft is used to transmit power from geared motor to the wheels
and also provides rigidity to the vehicle by withstanding all the loads. The
material used for shaft is mild steel. The diameter of the shaft is 20 mm. The
length of the shaft is 110 mm. Weight of the shaft is 0.25 kg. The lock nuts
are used at the end of the shaft to ensure that the wheel remains intact to the
shaft and do not run-off from the vehicle.
5.4.3.1 TRANSMISSION SHAFT:
Fig 5.4.3
52
5.4.3.2 LOCK-NUT:
Fig 5.4.4
53
5.4.4 FLANGE COUPLING:
There are 4 flange couplings used. They are used to transfer power from the
motor shaft to the wheels. The diameter of the male flange is 10 mm and the
diameter of the female flange is 20 mm.
5.4.4.1 MALE FLANGE:
Fig 5.4.5
54
5.4.4.2 FEMALE FLANGE:
Fig 5.4.6
55
5.4.5 SUB-ASSEMBLY PROCEDURE:
The tyre is mounted over the rim.
The one end of the shaft passes through the hub and other
end passes through the coupling.
The shaft of the gear box and the power transmission
shaft is connected by flange coupling.
The lock nut is placed at the outer end of hub over the
shaft.
5.4.5.1 EXPLODED VIEW
Fig 5.7
56
5.5 BRAKE ASSEMBLY:
Braking is to stop the movement of the wheel. Braking set up consists
of a lever which is hinged on one side and another side is free to move. The
free side is moved by cam which is activated by a stepper motor. The lining
material used is leather. The braking action is given to the shaft.
5.5.1 BRAKE LEVER-1
Fig 5.5.1
57
5.5.2 BRAKE LEVER-2:
Fig 5.5.2
58
5.5.3 STEPPER MOTOR:
Fig 5.5.3
5.5.4 CAM:
Fig 5.5.4
59
5.5.5 CLAMP-1
Fig 5.5.5
5.5.6 CLAMP-2:
Fig 5.5.6
60
5.5.7 SUB-ASSEMBLY PROCEDURE:
The stepper motor is fastened to one l-clamp and brake
lever is hinged to another l-clamp.
The cam is then fixed to shaft of the stepper motor and
positioned in such a way that is above the brake lever.
5.5.7.1 EXPLODED VIEW:
Fig 5.5.7
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5.6 CAMERA ASSEMBLY:
Camera is used for surveillance purpose. The cameras are placed above the
body. The camera is capable of rotating 360º. The stepper motor is kept
under the camera for the rotation of the camera. The camera is shielded with
covers. For the free rotation of the camera bearing is used. The range of the
camera used is 2 Km.
5.6.1 CAMERA:
Fig 5.6.1
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5.6.2 SENSORS:
Sensors are used for measurement of position, acceleration, speed of the
vehicle. The different types of sensors used in this UGV are position ,
proximity and acceleration sensors.
Position sensors are used to determine the position of the object. These can
be either linear or angular.
Different types of position sensors are
i) Linear variable displacement transducer
ii) Hall effect sensor
Proximity sensors are used to detect the presence of an object. They are
classified into
i) Non-contact type
ii) Contact type.
In this UGV non- contact type proximity sensors are used.
The different types of non-contact sensors are
i) Optical encoders
ii) Eddy current proximity sensor.
Velocity and acceleration sensors are used to monitor linear and angular
velocity and acceleration and detect motion.
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5.6.2.1 SENSOR CASING:
Fig 5.6.2
64
5.6.3 SHAFT CONNECTOR AND BEARING:
The connector is used to transmit motion from stepper motor to the
camera. The bearing ensure that the load is distributed to the body and only
the motion is rotary motion is transmitted to the camera. It also helps the
camera to rotate without friction.
5.6.3.1 SHAFT CONNECTOR:
Fig 5.6.3
65
5.6.3.2 BEARING:
Fig 5.6.4
66
5.6.4 STEPPER MOTOR:
Fig 5.6.5
67
5.6.5 CLAMP-1:
Fig 5.6.6
68
5.6.6 CLAMP-4
Fig 5.6.7
69
5.6.7 SUB-ASSEMBLY PROCEDURE:
The stepper motor is attached to the l-clamp at the bottom end
The bearing is placed over the L-clamp above which the camera
is mounted
The connector is mounted over the bearing and its shafts are
connected to the camera and the motor.
The L-clamp is attached to the sheet metal by bolts and nuts.
5.6.7.1 EXPLODED VIEW:
Fig 5.6.8
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5.7 BODY-ASSEMBLY:
The body covers the geared motors, batteries, micro controllers from
environmental effects thus protecting them. The body is designed in such a
way that the vehicle has a good aesthetic look. The body also holds the room
space for the camera and the sensors. The body can be fabricated using
injection molding and the super finishing can be provided by surface
grinding. The main idea of using plastic is to reduce the weight of the
vehicle.
5.7.1 BODY:
Fig 5.7.1
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5.7.2 DOOR, PARTITION PLATES AND ANTENNA:
Those are used for placing object inside the body and conceal it.
Partition plates provide the room space for pay load and restrict its
movements with its confined area. Antenna enhances the efficiency of signal
transmission.
5.7.2.1 DOOR:
Fig 5.7.2
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5.7.3 SUB-ASSEMBLY PROCEDURE:
The body is fastened with the vehicle by Allen keys.
The side doors are fixed to the body by hinged joint.
The antenna is screwed to the body at the top.
The plates are attached to the sheet metal by l-clamp.
5.7.3.1 EXPLODED VIEW:
Fig 5.7.3
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5.8 MICROCONTROLLERS:
The microcontroller forms the base for wireless tele-operation.It is
heart of the vehicle and controls all its operation. Long range signal
transmission and reception is done with the help of Zigbe module. Data
being sent is processed and necessary action is done by the microcontroller.
It also provides the feedback to the base station.
5.8.1 SUB-ASSEMBLY PROCEDURE:
Studs are fixed to the sheet metal. The circuit board and the
microcontroller are placed over the studs.
Fig 5.8
74
5.9 BOLTS AND NUTS:
The M8 and M4 bolts and nuts are used to fasten various parts with one
another.
Sub-assembly Bolt and Nut Bolt length Quantity
Frame-Assembly M 8 20 mm 8
Motor-Assembly M8 18 mm 24
Battery-assembly M 8 42 mm 4
Wheel-Assembly M 8 18 mm 16
Brake-Assembly M 8 and M 4 42 and 18 mm 8 and 16
Camera-
Assembly
M8 and M4 20 and 18 mm 6 and 4
Tab 1.2
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5.9.1 BOLT:
Fig 5.
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5.10 MAJOR ASSEMBLY PROCEDURE:
The sub-assemblies are carried out in the following order
1. Frame assembly
2. Motor assembly
3. Wheel assembly
4. Battery assembly
5. Brake assembly
6. Camera assembly
7. Micro controller
8. Body assembly
Then motor assembly is fixed to the sheet metal of the frame assembly
by l clamps, bolt and nuts.
The wheel assembly is then fixed to the motor assembly by fastening
the lock nut at one end and fastening the bolts and nuts of flange
coupling at the other end
Then battery assembly is fixed to the sheet metal by l clamps, bolt and
nuts.
Then the brake assembly is fixed by proper positioning of brake lever.
The friction lining of the lever must be positioned just above the shaft
of gear box and center line from shaft and brake lining must be
collinear
Then micro controller assembly is fixed to sheet metal the frame
assembly by positioning the studs
Then camera assembly is fixed to the sheet metal by l clamps, bolt and
nuts. The camera casing alone is initially removed to provide space for
body to be fixed.
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Now the body assembly is fixed by fastening the allen key and at last
the camera is fixed
5.11 UGV-BILL OF MATERIALS:
Fig 5.11
78
5.12 EXPLODED VIEW:
Fig 5.12
79
5.13 UNMANNED GROUNG VEHICLE:
Fig 5.13
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CHAPTER-6
CONCLUSION AND FUTURE SCOPE
6.1 CONCLUSION:
With the advancement in science and technology Robotics has taken a
giant leap towards the benefit of mankind. With its help various types of
sophisticated equipment are being made to aid in various fields viz,
medicine, engineering etc.
The large scale manufacture and induction of this vehicle into the armed
forces will be very beneficial for the country in terms of security. These
Vehicles are used to replace humans in hazardous situations. Since it is a
Radio Controlled vehicle it can be controlled from far of places, which can
be very useful during war situations in saving life and property. These
vehicles could be used in any kind of terrain and in the future these vehicles
would decide its own combat strategy. It can be used in difficult terrain and
for highly complicated security operations without any loss of human lives.
The CVRD has also started research on this type of vehicle and plan to
finish the project by 2020. The project will be an initiative at the college
level for developing such Combat Vehicles.
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6.2 FUTURE SCOPE:
The vehicle can be made to move in very rough terrain by
incorporating suspension system. If the efficiency of the suspension system
is large then the vehicle would be able to with stand heavy impact loads. An
robotic arm attached to the vehicle will largely extend its capability. Proper
incorporation of epicyclical gear train at the wheel will make the UGV to
climb steps .A feedback controller loop will make the vehicle to
communicate with us and working capacity and efficiency of the vehicle will
be greatly improved. If a gun is mounted over it for payload will make the
UGV as a combat vehicle apart from its surveillance capabilities.
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CHAPTER-7
7. REFERENCES
[1] Newton, Steeds and Garet,” Motor Vehicles “, Butterworth
Publishers,1989
[2] Bhandari, V.B., “Design of Machine Elements”, Tata McGraw-
Hill Publishing Company Ltd., 1994.
[3] A.G, “Mechanism and Machine Theory” Prentice Hall of India,
New Delhi, 2007.
[4] Ferdinand P Been, Russell Johnson,j.r. & John J Dewole
mechanics of materials,Tata Mcgraw Hill publishing Co Ltd,
NewDelhi,2006
[5] Williams D Callister, “Material Science and Engineering”
Wiley India Pvt Ltd, Revised Indian edition 2007.
[6] PSG Design data book
[7] “Machi Drawing” by N.D Bhatt and V.M Panchal.
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