Design and fabrication of AUTOMATIC GUIDED VEHICLE, WITH SIDE LIFT TROLLEY
Design and fabrication of AUTOMATIC GUIDED
VEHICLE, WITH SIDE LIFT TROLLEY
1.
Identification of the project
In
a modern manufacturing concern it is estimated that about 50 to 75% of cost of
production is spent in material handling activity, as majority of production is
consumed in handling materials before, during and after the manufacturing
process.
Possible Solutions:
This cost can be reduced by proper selection,
operation and maintain and layout of the material handling devices. Material handling can be defined as the
art and science of moving, packing and storing materials is any firm. This is prime factor considered in desisting
new plants. Proper material handling
increases output, improves quality, speedy deliveries and them reduce cost of
production.
The original machine based vision of automation using
powerful super robots to accomplish difficult tasks without human assistance
underestimated importance of communications.
Automated processes need to be highly configurable and flexible, they
are for expensive to be rebuilt for any design change. To successfully reconfigure an entire
industrial process, requires direct access to most of its control elements
–switches, valves, motors and drives down to a fine level of detail. This is
purely a matter of networked intelligence.
Thus automation can be summarized as a combination of
technologies, philosophies and disciplines that aim to make jobs or processes
more efficient, error free and fast. And
this sophisticated technology has changed the dynamics of manufacturing and
production. It has become main motor of
economic and technological progress.
Growing companies who harness it right, with rich dividends in terms of
success.
It is an interesting to note that facing automation is
also the foundation for all high-tech products.
Products which are common today like CPS can navigation systems,
cellular phones, small codes which are a result of miniaturization are in turn
dependent on advanced automation.
Intelligent machine is a device equipped with
senses. It can see, feel, smell and
read. Senior technology and machine
vision take on paramount importance in this area.
Proposed alternate solutions:
Automation cannot replace man and only achieve its full
potential when humans and machines interact appropriately. When work processes which are repetitive or
endanger health are automated, need for qualified specialist staff
increases. But automation technology is
also adapting itself more and more to humans.
Where friendly human machine interfaces, intuitive programming and teach
in methods point the way in this area.
Select best solutions:
For material handling and transportation for humans using
automation and adapting GPS navigation
to certain extent is not convenient which calls for automatic guidance as per
the road. We thought of adapting road guiding technique in which the sensors
will sense the road path and controls the drive mechanism of the vehicle. The
vehicle will follow the path of the road by getting guided by the colour
stickers on the road. The material is loaded by some mechanized means and
unloading is done by the mechanized lift
being activated by switch being provided. The trolley has a
gravity door which opens when lifted making the way for the material to be
unloaded.
Detail
design ;Driverless material handling vehicles:
These have improved optical guidance
system which is sensor controlled. These vehicles can be used where batch
production process change frequently, like loading and unloading points go on
changing, which may need to lay tracks as per the requirement, if it is of
track oriented. Here in this the track consists of a white line painted on a
black strip. There are three numbers of optical sensors, two of which are
taking the guide of the track width, which controls the steering motor, to
operate right or left side., center sensor senses the end of the path
controlling the drive motor., stopping at the end of the path. Once loading is
done, button is pressed, to move in the painted path. At the end of the path
the vehicle stops at the end of the painted strip.
The vehicle will consist four
wheels, rear one fixed on the drive axle with bearing holder, bearings drive
sprocket on it which is driven by the motor. The front wheels are mounted on
the hub with pivots which are connected to the tie rods which is driven by the
rack and pinion gears, this assembly is driven by a motor which controls the
steering mechanism. Three sensors are provided at the front base fixed at a
fixed distance between them so as to sense the painted strip on the road with
opaque background for a width of 5 inches on which a white patch of 3 inches is
sticked. The end two sensors senses the outer edge of 3 inches so as to control the
steering, once the sensor moves out the way of 3 inches it triggers the circuit to
control the steering motor to rotate in that direction and get adjusted to the
strip.
Ø
This vehicle consists of four wheeled chassis. The drive for
this chassis is given by DC motor through chain sprocket.
Ø
Then for steering simple rack and pinion mechanism is used at the
front wheels and the mechanism is actuated by DC motor, which is controlled by
the control circuit.
Ø
Optical Sensors are provided at the front portion which senses the
road path and activates a circuit which controls the steering mechanism and the
drive motor.
Ø
Trolley is pivoted on pins and bushes and is lifted by leadscrew
mechanism being driven by a DC motor to the required inclination for unloading.
Advantages:
·
Man control saving, in time and cost
·
Longer durability of batteries
·
Saving in man control driving, carrying since the effort of the
driver is reduced
·
Integrated work hour meter, and also maintenance free.
·
Very helpful in hazardous material handling.
·
Switches off automatically when reaches the destination.
Working methodology:
This is a trolley
based guided vehicle which moves in a fixed path, which is preset by the
stickers. This vehicle is having steering mechanism and drive mechanism through
motors which are powered by batteries inbuilt within the vehicle. The vehicle
is fixed with optical sensors which senses the opaque colour and triggers the
circuit to control the direction of the steering motor to adjust the steering
as required to keep it on the road. There are three sensors out of which two
extreme end sensors will control the steering and the center sensor will
control the drive motor, will stop the motor when the colour sensing ends.
The vehicle will be started to drive in the path
being set as stickers will follow the path maybe in curved or straight path or
angular and will stop at the end of the path, which means no sensing by the
sensor. After stopping at the end of the destination, the lift motor gets
activated by unloading of the material
is done by the one end of trolley being lifted up to dump the material down. The button pressing and the
lifting starts and ends and return back to rest by button.
2. General information
Industrial robots
are reducing labour costs, boosting productivity, and minimizing errors. Not to mention liberating workers from
dangerous, repetitive, mundane tasks.
Robotic systems are being deployed in factories, buildings, cell phones,
packaging, light bulbs, and even making cookies. Robots had resurrected. What brought about the resurrection of the
industrial robot? The answer is simply ‘better robots’, in the ‘80s, with the
robotics industry in a tailspin, robotics companies focused on improving
hardware, specifically the actual mechanics of robots. They switched from hydraulically run robots,
with a tendency to leak, to electric ones.
Furthermore, many companies have moved from harmonic-drive, gear-driven
motors to direct-drive motors, which arguably increase the speed, accuracy, and
longevity of a robot.
Robots have
become so accurate that they can be applied where manual operations are no
longer a viable option.
The same
consistent high level of output, power and quality cannot be achieved with
humans and simple mechanization. So
today, precision robots account for the explosive production of miniaturised
electronic components and devices, such as those in the mobile phone.
Applications like
spot welding, painting, and dispensing have also benefited greatly from the
advancements in microprocessors. The
doors have been thrown open for a myriad of other applications outside the
automobile sector, which still accounts for roughly half of the robot
sales. But in a clear indication that
the robotics industry is becoming less dependent on the automotive sector,
material handling has dethrone spot welding as the dominant robotic
application. Robot are now used in a wider range of industries. We are at the thresh-hold of a robotic
revolution.
Most industrial
robots until recently, couldn’t see, and there are few examples of bipedal,
upright walking research robots such as Honda motor Company’s P3.
Although the modern
robots don’t exactly resemble humans, the vision-guided versions are a little
closer to Capek’s imagination. The
integration of machine vision systems (using cameras and computers) in robots
has increased their flexibility to perform a great variety of tasks. The robot has learned to see and use this
sense of vision to become more autonomous.
.
Our project “Automated guided vehicle for material
handling” is a small step forward in understanding the vast field of
industrial robots. Industrial robots are beginning now to revolutionaries
industries. These robots do not resemble
humans nor behave like one, but do the work of humans. Robots are particularly useful in a wide
variety of industrial applications, such as material handling, painting,
Welding, inspection and assembling.
Our project deals
with controlling the operations of industrial material handling robot which
uses optical sensors to read the road and control the movement automatically,
avoiding a driver, saving human cost.
3. INTRODUCTION
Robotics belongs to a branch called Mechatronics. Mechatronics is a term coined by the Japanese
to describe the integration of mechanical and electronic engineering. More specifically it refers to a
multidisciplinary approach to product and manufacturing system design. It represents the next generation machines;
robots and smart mechanism for carrying out work in variety of environments predominantly
factory automation, office automation and home automation.
Man has been toying with the idea of mechanical version
of himself that led to the successful introduction of robots. The word ‘robot’ comes from the Czech word
‘Robota’ meaning ‘forced labor’.
An industrial robot is defined as “a reprogrammable
multifunction manipulator designed to move materials, parts, tools, or
specialized devices through variable programmed motions for the performance of
a variety of tasks.”
Robots like machine tools are available in a variety of
types, styles and size. Generally they
are described as either servo or non-servo.
Non-servo robots have no servo drives and have limited controls over
speeding up or slowing down movements.
Servo robots are determined by their electric and hydraulic drives. Servo drive models range from pick-and-place
units to those with multiple capabilities.
4. FUNDAMENTALS
OF ROBOTICS
4.1 CLASSIFICATION OF
ROBOTS:
Robots come in a different sizes and forms and with
different
Capabilities. The various types
of robots could be classified
·
Based on manipulative function
ü Pick and place robots
ü Special purpose robots
ü Universal robots
·
Based on configurations
ü Rectangular Co-ordinate
ü Cylindrical Co-ordinate
ü Spherical (polar)
Co-ordinate
ü Jointed arm robots
·
Based on motion characteristics
ü Point to Point robots
ü Continuous path robots
·
Based on drive system
ü Electric Drive
ü Pneumatic Drive
ü Hydraulic Drive
·
Based on Generation
ü First Generation robots(Simple Programmable)
ü Second Generation robots(Capability to understand the environment
by acquiring data)
ü Third Generation robots (Intelligent robots)
4.2 CONFIGURATION OF
ROBOTS:
Industrial
robots are generally classified as:
A) RECTANGULAR C0—ORDINATE ROBOT:
The main frame of
this type of robot consists of three orthogonal linear (prismatic/sliding) axes
and it has a rectangular work volume.
B) CYLINDRICAL CO-ORDINATE ROBOT
It consists of
two linear axes and one rotary axis, and the work volume is a cylindrical
annular space.
C) SPHERICAL C0-ORDINATE ROBOT:
It has a rotary
base, an elevated pivot and a telescopic arm.
The work volume is a thick spherical ball.
4.3 ROBOT AND ITS PERIPHERALS:
ROBOT ARMS:
The simplest arm
is the pick-and-place type. In this case
parts are moved from one location to another without caring how the part is
picked up or put down. But today robot arms are designed to manipulate objects
having complicated shapes and fragile in nature. They may be used to assemble parts or fit
them into clamps and fixtures. This is
possible due to high accuracy attained in robot’s arm. It is possible to hold the part securely
after picking up and in such a way that the position and orientation remain
accurately known with respect to the arm.
ROBOT HANDS:
Present day robot
hands comprise of controlled arms with improved grippers backed up by passive
or instrumental wrists. Dexterous hands
have been developed to handle fragile objects.
It must however be understood that there is always an inherent trade off
between dexterity and strength.
The primary goal
for a manufacturing hand is to solve the dexterity verses strength trade off in
the context of the machine tools and flexible manufacturing/assembly
systems. The aim is to build a hand with
sufficient manipulating abilities without unduly sacrificing power.
END
EFFECTORS:
End effectors are
devices that attach to the wrist of the robot arm and enable the
general-purpose robot to perform a specific task. The end effectors are a part of that special
purpose tooling for a robot.
The various types of end
effectors
- Grippers
- Tools
Grippers are end
effectors used to grasp and hold objects.
Grippers as mechanical grasping devices, but there are alternative ways
of holding objects involving the use of magnets, suction cups, or other means. Grippers are classified as
o
Mechanical grippers
o
Vacuum cups
o
Magnetic grippers
o
Adhesive grippers
o
Electrical and
electromagnetic grippers
In many
applications, robot is required to manipulate a tool rather than a work
part. The use of gripper permits the
tool to be exchanged during the cycle and thus facilitates this multi-tool
handling function.
In most of the
robot applications, the tool is attached directly to the robot wrist. Some examples of tools used as end effectors
in robot applications include:
- Spot welding tools
- Arc welding torch
- Spray painting
- Rotating spindle for operations such as-
- Drilling
- Routing
- Grinding
- Wire Brushing
- Heating torches
- Water jet cutting tool
4.4
DRIVE SYSTEMS:
Industrial robots
are powered by one of three types of drive systems. These three systems are:
1. HYDRAULIC DRIVES
This is generally
associated with larger robots. This
drive provides the robot with greater speed and strength. The disadvantages of hydraulic drive system
are that it typically adds to the floor space required by the robot. Hydraulic drive systems can be designed to
actuate either rotational joints or linear joints.
2. ELECTRICAL DRIVES
These systems do
not generally provide as much speed or power as hydraulic systems. However, the accuracy and repeatability of
electric drive robots fare usually better.
Consequently, electric robots tend to be smaller, requiring less floor
space. DC stepping motors or DC servo
motors actuate electric drive robots.
These motors are ideally suited to the actuation of rotational joints
through appropriate drive main and gear systems.
4.5
SENSORS IN ROBOTS:
Sensors used as
peripheral devices in robotics include both simple types such as limit switches
and sophisticated types such as machine vision.
Of course, sensors are also used as integral components of the robot’s position
feedback control system. Their function
as peripheral devices in a robotic work cell is to permit the robot’s
activities to be coordinated with other activities in the cell. The sensors in robotics include the following
general categories:
- TACTILE SENSORS
These are the sensors, which respond to
contact forces with another object. Some
of these devices are capable of measuring the level of force involved.
- PROXIMATE AND
RANGE SENSORS
A proximity sensor is a device that
indicates when an object but before contact has been made when the distance
between the objects can be sensed, the device is called range sensor.
- MISCELLANEOUS
SENSOR
This includes the remaining kinds of sensors that are used
in robotics. These include sensors for
temperature, pressure and other variables.
- MACHINE
VISION
A machine
vision is capable of viewing the workspace and interpreting what it sees. These systems are used in robotics to perform
inspection, part recognition and other similar tasks.
Sensors are important components
in work-cell control and in safety monitoring systems.
4.6
APPLICATIONS OF ROBOTS:
v Manufacturing
o
Deburring
o
Die-casting
o
Fitting
o
Forging
o
Investment casting
o
Plastic molding
v Loading, Unloading and Movement of Parts
o
Machine loading and
unloading
o
Work piece transfer
v Welding and Cutting
o
Arc welding
o
Spot welding
o
Laser cutting
o
Water jet cutting
v Painting
o
Spray painting and coating
v Design and Assembly
o
Product design
o
Assembly sequencing
o
Inspection
o
Layout analysis and
evaluation
5. COMPONENTS OF ROBOT
Since we are
using electrical drive systems, therefore two types of elements are
possible. Out of one is obviously
mechanical components and the other one is electrical & electronic
components.
5.1) MECHANICAL COMPONENTS:
Fabrication is an
interesting exercise, which involved changes to be incorporated into the design
either because of error in calculating certain dimensions or due to
difficulties in fabrication and the option of better and easy method of
manufacture. The following discussion
includes how each part of the robot is fabricated along with their dimensions.
Working
of circuit
In our model we
are using machine vision sensors which are termed as optical sensors which
senses the reflection of the emitting light, the sensitivity can be set in the
circuit.
In this infrared
emitters are placed along with the photo transistor which when senses the
opaque colour, will reflect and keep on sensing which gives low voltage input
at pin number 7 of IC UM606 which gives a inverted output at pin number 6 which
conducts the transistor BC 547 which
triggers the relay to connect the motor to operate in clockwise direction.
Similarly another set of IR emitters and photo transistor and IC UM606 and
transistor and relay are connected to give output to the motor to rotate in the
anticlockwise direction, thus controlling
the steering mechanism. Third set of IR and other parts are operating to
sense the drive, which cuts off the supply to the drive motor when not sensing
anything.
IC- UM- 606 DC TIMER
PIN CONNECTION
A timer UM-606 is
available in market in following package:
- 8
Pin DIP package
- 8
Pin metal can
Pin No. 8:
Ground
Pin No. 7 : Trigger
Pin No. 6:
Output
Pin No. 5:
Reset
Pin No. 4:
Control
Pin No. 2:
Threshold
Pin No. 3:
Discharge
Pin No. 1:
Vcc.
DETAILS OF PINS OF TIMER um-606
dc
Pin No. 8:
This is the
common or ground terminal. Negative
terminal of power
Supply is connected at this Pin.
Pin No. 7:
The trigger
voltage of lower comparator is applied at this pin. Normally, the
voltage at this pin is at least two-third
of the supply voltage (+Vcc). The output remains low in this
condition. When a negative going pulse,
which is more than one-third of +Vcc is applied at Pin No.2. then the circuit
is triggered. The flip-flop changes its state and the output becomes high. Thus, remains low and when the voltage at Pin
No.2 is more than one third of +Vcc then the output remains low and when the
voltage at Pin No.2. is less than one third of +Vcc, then the output goes high.
Pin No. 6:
This is the
output pin. This output has two logic
states. The output in its low state is
almost equal to the ground, and in the high state this output is almost equal
to +Vcc.
Pin No. 5:
This is the reset
input pin which controls flip-flop directly.
As its name suggests, the signal at this pin returns the device to its
original state. When the reset terminal
is connected to the ground then the Pin No.3 (output) and Pin No.7 become low
that is the voltage at these pins becomes almost 0V. When the reset terminal is not used then Pin
No.4 should be kept connected to +Vcc.
Pin No. 4:
This is the
control voltage input Pin. Generally this pin is not used and is kept connected
to the ground through a 0.01M capacitor.
Any external voltage at Pin No.5 will change both the threshold and the
trigger voltage reference levels.
Pin No. 2:
This is the input
pin for threshold voltage of the upper comparator. A timing resistance is connected to Vcc from
Pin No.6. This Pin No.6 is also
connected to the ground by an external capacitor begins to charge through the
timing resistance. When the voltage
across capacitor reached the threshold level then the output becomes low.
Pin No. 3:
It is the
discharging the external capacitor.
Usually Pin No.7 is kept connected with the Pin No.6 directly or through
a resistance. When the output becomes
low at Pin No.3 then the external capacitor is discharged by the internal
discharge transistor. When the output at
Pin No.3 goes high then the internal discharge transistor remains cutoff and
the external capacitor charges towards Vcc.
Pin No. 1:
This is the
positive voltage supply terminal and is
connected to +Vcc. The voltage at this
Pin No.8 should be between +5V and +15V.
6. DESIGN
6.1 DESIGN OF AXLE:
V
= 12
Volts
I
= 3.8 Amps
N
= 36
Rpm
P
= V
x I
= 12
x 3.8
= 45.6
watts
P = 2p N Tmean
60
2p x 36 x Tmean
P
=
60
2p x 36 x Tmean
45.6
=
60
Tmean
= 12.09 N – m
Tmean
= 12.09 x 103 = 12090
N – mm
Max
load on trolley = 2.5 kg
= 2.5
x 9.81
= 24.5
N
L
= Distance
between wheel center
= 60
mm
M
= Max
bending moment = W x L = M = 24.5 x
60 = 1470 N – mm
- Max Shear Stress theory
Te = Ö M2 + T2
= Ö 14702 + 120902
= 12179.03 N – m
Te = p/16 fs d3
fs = 42 N /mm Permissible sheer stress for mild steel
Te = p/16 fs d3
12179.03 = p/16 x 42 x d3
d3 = 1476.84
d = 11.38 mm
- Max normal stress theory
Me = ½ (M + Ö M2 + T2 )
= ½ (1470 + Ö 14702 +
120902 )
Te = ½ x 6824.51 N – mm
fb = 112 N/mm permissible pending stress for mild steel
material
Te = p/32 x fb x d3
6824.51 = p/32 x 112 x d3
d3 = 620.66
d = 8.53 mm
Larger of two value of diameter
d =11.38 mm so adopt
d = 12mm
6.2 DESIGN OF Bearing:
THE INNER
DIAMETER of the bearing is press fitted to the outer diameter of the column
with the help of brazing. Depending upon
the diameter of the column the selected bearing is deep groove ball bearing. The standard dimension of this bearing is
given below.
Bearing of design No (SKF) : 6209
Inner diameter : 15mm
Outer diameter : 35 mm
Breadth : 10 mm
7. DRAWINGS
Rear Axle Mtl :
C30 Qty: 1 Nos
Bearing Housing Mtl:
Mild Steel Qty: 4 Nos
Motor Clamp Mtl:
Mild Steel Qty: 2 Nos
Front Axle Mtl:
Mild Steel Qty: 2 Nos
Wheels Mtl
: Plastic Qty: 4 Nos
Driven Sprocket Mtl
: C30 Steel Qty: 1 Nos
Drive Sprocket Mtl
: C30 Steel Qty: 1 Nos
Lifter Lead Screw Mtl : C30 Steel Qty: 1 Nos
Nut
Mtl : C30 Steel Qty: 1 Nos
Approximate
size. 700mm length; 450mm
height.;500mm width.
Circuit Diagrams
8. FABRICATION
BEARING:
We are using ball
bearing of rolling contact type. These
bearings are used for light loads.
Dimensions:
For wheels:
Inner diameter:
15 mm
Outer diameter: 35 mm.
WHEELS:
Plastic ready
made wheels are brought and centre bore is made to 15 mm. The outside diameter
is 200mm and the width is 75mm. Total four number of wheel are used, two for
front and two for rear side.
FRAME:
Flat stripes of
size 20x5 mm are cut as per the requirement and joined by welding. Requisite drillings are done as per the
drawing. Material used for the frame is
Mild steel.
REAR AXLE.
Round mild steel
bar of diameter 24mm is taken and then it is turned on the lathe machine to
make steps diameter of 20mm to suit the sprocket and 15mm to suit the ball
bearing and the both ends 14mm to suit the plate washer which holds the plastic
wheels.
Bearing housing for rear
axle.
It is turned on
the lathe machine for the diameter of 45mm outside and internal step bore is
made to suit the ball bearing of diameter 35mm for the depth of 15mm and center
hole is made of diameter 15mm. The total length maintained is 20mm. It is face
turned from the backside. The M10 bolt
is welded on the top circumference to hold the chassis on it. Quantity turned
is 2nos for the backside.
Bearing housing for front
axles.
It is again
turned on the lathe machine for the required size diameter of 45mm is step
truned to house the ball bearing from the inside for the depth of 15mm and the
centre hole is made of diameter 15mm. The backside plate of 70mmdiamenter is
welded to the face of this bearing housing so that it is bolted to the plastic
wheel.
Front axle:
20mm square bar mild steel
is taken and turned on the lathe machine to maintain the step of diameter 15mm
to suit the ball bearing for the length of 65mm. A cross hole is made of
diameter 10mm to suit the pivoting pin being protruding from the chassis frame
on which this axles is held. Two numbers are turned and fitted at both the
sides. The mild steel flat of 20mmx3mmx40mm is welded to the front axle pin
which is fitted to the rack gear of steering. The drill of 6mm is made at the
end of this flat in which the rack gear end is pivoted.
Rack gear
A C30 steel rod of diameter
8mm is taken and turned to the size of 6mm with the rack gears ion the lathe
machine, like the threading operation, for the length of 150mm and pitch of
3mm.
Pinion gear
A C30 steel of diameter of
26mm is taken and turned to the diameter of 24mm and step turned to the
diameter of 10mm. It is then loaded on the milling machine to cut the teeths
21nos of teeths.
Steering rack ends
The C30 steel square bar is
taken and turned on the lathe machine for the step diameter of 9mm and 8mm as
per the drawing and at one end drilling is done at the centre for the diameter
of 6mm to suit the rack gear. The rack gear is press fitted in this.
Drive sprocket
A standard sprocket is
taken with the teeth of 18 and a plug is turned
for the diameter of 34mm outside and 10mm internal diameter to suit the
motor spindles. The turning is done for step diameter of 20mm. This sprocket is
locked on the motor spindle.
Driven sprocket
A standard sprocket of
18teeths is taken and a mild steel round bar is turned and plugged in this
sprocket to bore the internal diameter as 20mm to suit the rear axle and get
locked with the rear axle of size 20mm.
Sensor holder plate
A mild steel flat is taken
of size 20mmx3mm is taken and bent to the required contour and drilled to hold
the sensor circuit board at the front portion of the vehicle by bolt and nut.
Motor clamp
A mild steel flat
is taken of size 25mmx5mm for the length of 225mm and it is bent to the circle
to maintain the diameter of 75mm to hold the motor. Same size two number of
motor clamp are made. It is welded at the end and M10 nut is welded on it after
drilling on the circumference.
Lifter lead screw
It is made out of C30 steel
being turned from the round bar of 22mm diameter for the length of 160mm to
make the diameter of 20mm and step diameter of 15mm for the length of 40mm. The
square threading is done by settting the pitch of 5mm. Each cut given while
threading is 0.3mm.
Lifter nut
It is made out of C30 steel
of diameter 40mm and length of 20mm turned on the lathe machine to make the
diameter 38mm and faced to make the length to 15mm and drilled and internal
threading is done for the pitch of 5mm to suit the squre threading of the leadscrew.
Pivot bushes
It is made out of
mild steel of diameter 20mm for the length of 10mm drilled for the diameter
10mm and faced from both the sides.
Pivot pins
It is made out of mild
steel of diameter 20mm for the length of 20mm being step turned for the
diameter of 10mm and 19mm to suit the bushes. A circlip groove is also made to
accomodate the locking of the bushes.
VEHICLE COVER:
Mild steel sheet
of 1mm are used to cover the vehicle and it is made to shape as required. The
cabin is also designed and made to hold the tool boxes and th trolley is made
to hold the material in it.
ELECTRICAL COMPONENTS:
Motors
There are variety
of types of motors used in robots, they include dc servomotors, stepper motors
and ac servomotors among these motors we have used dc servomotors. The main components of dc servomotors are
rotor and the stator. Usually, the rotor
includes the armature and the commutator assembly and the stator includes the
permanent magnet and bush assembly. When current flows through the winding of
the armature it sets up a magnetic field opposing the field set up by the
magnets. This produces a torque on the
rotor. As the rotor rotates, the brush
and commutator assemblies switch the current to the armature so that the field
remains opposed to the one set up by the magnets. In this way the torque produced by the rotor
is constant through out the rotation.
Another effect associated with the dc servomotor is the back-emf. The effect of the back emf is to act as
viscous damping for the motor.
SPECIFICATIONS:
RATINGS:
System voltage : 12 V
Operating temperature : 20°C to +90°C
CHARACTERISTICS:
Typical light running current :
3.8 Amps
Rated torque at output gear :
18 to 25 Nm at 12V
Operating speed :
30 r.p.m
BATTERIES:
Voltage :
6 V
Current :
3.8 Amps
Steering mechanism
8
Topview
|
Sl. No |
PARTICULARS |
SIZE |
UNIT |
QUANTITY |
|
1 |
Bearing Housing |
Ø45 X 20 |
MS |
02 |
|
2 |
Ball Bearing |
15/35/10 |
STD |
02 |
|
3 |
Axle |
Sq 20X65 |
C30steel |
02 |
|
4 |
Connector |
3 * 20 * 50 |
MS |
02 |
|
5 |
Link Connector |
3 * 20 * 50 |
MS |
02 |
|
6 |
Rank Screw pith 3.5mm |
¢6.35 * 125 |
C30steel |
01 |
|
7 |
Screw Housing |
90X30X14 |
CRCA |
01 |
|
8 |
Pinion Gear |
¢20 X 4mm |
C30steel |
01 |
|
9 |
Gear Shaft |
¢12X60 |
C30steel |
01 |
|
10 |
Connector Pin |
¢10 * 30 |
C30steel |
04 |
|
11 |
Gear Shaft Bush |
¢15 * 25 |
MS |
01 |
|
12 |
Motor |
12v DC |
STD |
01 |
9. ESTIMATION
AND COST ANALYSIS
Parts involved:
|
Sl. No. |
Name of the Parts |
Material used |
Qty. |
Cost in Rupees |
|
1. |
Wheels
|
Fibre
Plastic |
4
Nos. |
500.00 |
|
2.
|
Hub
|
Mild
Steel |
4
Nos. |
500.00 |
|
3.
|
Ball
Bearing |
Standard |
4
Nos. |
500.00
|
|
4. |
Steering
Mechanism |
Steel
|
1
Set |
1200.00 |
|
5. |
Drive
Motor |
Standard
|
1
Nos. |
1200.00 |
|
6.
|
Steering
Drive Motor |
Standard
|
1
Nos. |
900.00 |
|
7.
|
Drive
Sprocket |
Steel
|
2
Nos. |
400.00 |
|
8. |
Fabricated
Frame |
Steel
|
1
Set |
700.00 |
|
9. |
Bearing
Housing |
Mild
Steel |
2
Nos. |
800.00 |
|
10. |
Sensor
Holder |
Mild
Steel |
1
Set |
450.00 |
|
11 |
Sensors
|
Electronic
|
3
Nos. |
1200.00 |
|
12 |
Control
Circuit |
Electronic
Parts |
1
Set |
1400.00 |
|
13 |
Battery
|
12
V, DC 3.2 Ah |
2
Nos. |
500.00 |
|
14 |
Battery
Charging System |
Electronic
|
1
Set |
550.00 |
|
15. |
Pivoting
Pins |
Mild
Steel |
1
Set |
450.00 |
|
16 |
Body
|
CRCA
Steel |
1
Set |
900.00 |
|
17 |
Screw
for Lifting Mechanism |
C30
Steel |
1
Nos. |
500.00 |
|
18 |
Nut
for Lifting Mechanism |
C30
Steel |
1
Nos. |
300.00 |
|
19 |
Motor
for the Lifter |
12
V DC, 3.2Amps
36RPM |
1
Nos. |
300.00 |
|
20 |
Pivot
Bushes and Pins |
Mild
Steel |
2
Set |
300.00 |
|
21 |
Stopper
|
Mild
Steel |
1
Set |
200.00 |
|
22 |
Trolley
|
G.I.
Sheet |
1
Set |
103.50 |
Estimation of Trolley:
0.07m
0.46 mt 0.540 m
Thickness
of the sheet = 0.01m
Sheet
metal required = 1 (0.46 x 0.54) + 2 (0.07 x 0.46) + 1 (0.070 x 0.54)
=
0.248 + 0.0644 + 0.0378
Sheet
metal required = 0.3502 m2
Assuming
scrap = 5%
=
5/100 x 0.3502
=
0.0175m2
Total
sheet metal required
=
0.350 + 0.0175
Total
sheet metal required
=
0.36771 m2
Volume
of sheet metal = Area x Thickness
=
0.36771 x 0.001
=
0.00036771 m3
Volume = 0.00036771 x 106 cm3
Weight
= Volume x Density r
= 8gm/cc
=
0.00036771 x 106 x 8
=
2941.68 grm
W
= 2.941 Kg
Assuming
cost of the sheet = 32/Kg
Cost
of Sheet Metal
=
32 x 2.941
=
94.112 Rs.
Material
cost = sheet metal cost
=
94.112 Rs.
Labour
cost = 10% material cost
=
10/100 x 94.112
=
9.4112 Rs.
Total
cost of the trolley = Material cost + Labour cost
=
94.112 + 9.4112
=
103.5 Rs.
10. SCOPE FOR THE FUTURE
DEVELOPMENTS
The following
discussion includes the scope for future work for the fabricated robot.
- Here
the entire robot is controlled by automatic guidance of the path and the
operation can be controlled by interfacing the robot to a microprocessor.
- Material
loading and unloading if provided it will be usefull.
AGVs—Automated
guided vehicle system helps by reducing labor and material costs while
improving safety and equipment damage.
In Automotive industries similar kind of automated guided vehicles
are used :
In
chemicals and plastics they can be used in such manner, AGVs for handling raw
materials and finished goods---
In printing
industries these can be used in such manner, for newsprint movement---
In hospitals
these can be used in such manner. Automated transport systems for healthcare
facilities---------
11. CONCLUSION
As a project we
had purpose to design and fabricate automated guided vehicle used for material
handling. Using electric drive DC motor
we achieved required motion of the vehicle.
The control of
sensing and control of the motion motors for driving and steering is done
by circuit.
The motion of
vehicle synchronized for drive and steering worked in control of the circuit.
As economy of project is considered it is cheap one.
Thus it is
concluded that overall performance of the Guided vehicle is satisfactory.
BIBLIOGRAPHY
- CAD/CAM and Robotics by B.A.
Srinivas
- CAD/CAM and Robotics by K.C.
Vakkalad
- Industrial Robotics by Mikell P.
Groover
- Computer Aided Manufacturing by
P.N. Rao, N K Tewari
- Text Book of Machine Design, by
R.S.Khurmi & J.K. Gupta
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