UGV

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.

2

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.

3

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

4

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

5

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

6

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.

7

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.

8

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.

9

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.

10

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.

11

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

12

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

13

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

14

{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

15

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

16

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

17

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

18

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

19

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

20

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.

22

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

23

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.

25

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

26

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

27

Real Constrain Add/Edit/Delete

Thickness 2D

Close

Material Properties Material Mode

Structural

Linear

Elastic

Isotropic (2×105, 0.32)

Close

Modeling Create

Area

28

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

30

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

31

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

32

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

33

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

34

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.

37

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

39

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

44

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


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

49

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


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

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5.5.3 STEPPER MOTOR:

Fig 5.5.3

5.5.4 CAM:

Fig 5.5.4

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5.5.5 CLAMP-1

Fig 5.5.5

5.5.6 CLAMP-2:

Fig 5.5.6

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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.


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

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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

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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


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.


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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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.


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.


Studs are fixed to the sheet metal. The circuit board and the

microcontroller are placed over the studs.

Fig 5.8

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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

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5.12 EXPLODED VIEW:

Fig 5.12

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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.

UGV

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