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

2p x 36 x Tmean

P =

2p x 36 x Tmean

45.6 =

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

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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