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CHAPTER 01Introduction

Automatic Object Retrieval System (AORS) is generally termed as Automatic

Storage and Retrieval System (AS&RS). It refers to a variety of computer-

controlled methods for automatically placing and retrieving loads from specific

storage locations.

AS&RS are categorized into three main types: single mast, double mast and man-

aboard. Most are supported on a track and ceiling guided at the top by guide rails or

channels to ensure accurate vertical alignment, although some are suspended from

the ceiling. The 'shuttles' that make up the system travel between fixed storage

shelves to deposit or retrieve a requested load (ranging from a single book in a

library system to a several ton pallet of goods in a warehouse system). As well as

moving along the ground, the shuttles are able to telescope up to the necessary

height to reach the load, and can store or retrieve loads that are several positions

deep in the shelving.

To provide a method for accomplishing throughput to and from the AS&RS and the

supporting transportation system, stations are provided to precisely position inbound

and outbound loads for pickup and delivery by the crane.

1.1 Objective

Control and Automation is a key player in optimizing the performance of our

industry as well as academia. This project is a kind of subset of AS&RS. Main

objective of doing this project is to grasp the key concepts of control and

automation. The main components of the project are as follows:

A wooden shelf to place dummy materials



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A steel structure carrying the shuttle to retrieve and place back the material

again.

A controller circuit to control the movement of shuttle in X, Y and Z axis.

A laptop / desktop computer to give commands. (The system can be

converted into an embedded system as it is controlled by a µ - controller.

Programming software to program the µ - controller for the three different

motors installed for the movement of shuttle.

The work focuses on developing the prototype model with basic functions to

enhance the understanding and working of the AS&RS on one hand and hone the

skills of control and automation concept on other hand.

1.2 Organization of the Report

Chapter 2 is the literature survey. Efforts have been made to find as much material

on the topic related to the project. A good number of research papers as well as and

other related material on this subject was found, references have been included and

the interested reader can get the required information from there. This survey

comprised of the most recent trends, with the hope that the future implementer will

have rich and updated resource to enhance this project further more.

Chapter 3 is the physiology of the project. All components have been explained

item by item along with their theoretical references. The shuttle, the steel structure

holding the shuttle and the controller circuit have been discussed in detail.

Chapter 4 is the operational details of the project. The sequences of shuttle

operations as well as the key pad commands have been discussed in detail. The

work flow model of the system is also a part of this chapter.

Chapter 5, the last chapter broached some future aspects as well as the conclusion

driven from the experiment. This chapter is followed by a few appendices,

manifesting the code as well as related spec data of the electronic components of the

project.



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efficiency of existing systems. Suesut, T. Mongkhoin, B7. Presented a forecasting

approach for inventory control systems. Suesut, T.8

etal., published another finding

with respect to ware house automation. Byung-In Kim9

etal. also contributed by

presenting an idea of agent based framework for warehouse control. Order trays and

gantry robots (picking devices) are modeled as intelligent agents that behave in a

cooperative manner so as to achieve personal and system wide goals. The model has

been applied to a real world warehouse using actual data. The system is capable of

significantly shortening picking cycle time without compromising on system

efficiency. It also produces significantly fewer picking errors compared to a

hierarchical model used by the company.

Research was not limited to increase the efficiency of software models of thecontroller, though it was done for the controller itself. Chao-Huang Wei Shang-

Ping Chen11

presented a teleautonomous system for AGV path guidance. This

system uses the generation of virtual force as force feedback and virtual 3D scene as

visual feedback in the teleautonomous control loop, whereas a human intervention

is required. To guide an AGV through environments, where some areas are marked

as restricted yet not bounded with a closed wall, it is necessary to create a virtual

wall in the 3D scene. Whenever the operator drives the AGV near to a predefined

forbidden zone or an obstacle, a virtual force exerts on the joystick forbidding

further movement. Meanwhile the operator obtains acoustic and visual signal

through VR system. Simulation results show that this method provides better AGV

guidance with less error.

Similar kind of work can be found in10, 12 – 18

and can be referenced for further

development of the project discussed in this report.



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CHAPTER 03

The AORS Broached

Automatic Object Retrieval System (AORS) is an application of feed back control system.

The prime objective is to retrieve a specified item from a specified location. In order to reach

a certain location movement is required which is achieved by motors. As the motors are

moving in a controlled fashion, hence a feedback element is there to control the movement.

This specific prototype model can also serve as an example of Human Machine Interface

(HMI) as the end user has to press the desired shelf/rack number and the rest of the

calculations are done at machine level to reach the destination. The logical arrangement of

the components can easily be understood by system block diagram on next page.

3.1 Components of AORS

AORS functionality is achieved with the help of following components.

Stepper motor

DC motor

Rotary Encoder

Microcontroller

Keypad

Reset Circuit

Oscillator Circuit

Stepper Motor Circuit

H – Bridge Circuit

Each of the components is explained below individually along with certain theoretical

background information as ready reference, to aid in grasping the functionality of each

component easily. It may be noted that horizontal movement of the shuttle is defined as x –

axis, while vertical movement is defined as y – axis and inside/outside movement in the rack

is defined as z – axis movement.



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Figure 3.1 (Block Diagram)



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3.2 Stepper Motor

Stepper motor is used for x – axis movement of the shuttle. This is the first movement

whenever a key is pressed from the keyboard. The micro – controller identifies the key

pressed, decodes it in a binary signal and sent the required set of bits at its output pins. The

output pins are connected to the stepper circuit (discussed later on) and this drives the shuttle

to the desired location at x – axis. Some basic information about the construction and working

of stepper motor is as follows.

3.2.1 Preamble

Motors come in many different types, shapes, and sizes. Most of the motors used in motion

control can be divided into two categories: stepper motors and servo motors. Stepper motors

are less expensive and typically easier to use than a servo motor of a similar size. They are

called stepper motors because they move in discrete steps. Controlling a stepper motor

requires a stepper drive and a controller. A stepper motor is controlled by providing the drive

with a step and direction signal. The drive then interprets these signals and drives the motor.

Stepper motors can be run in an open loop configuration (no feedback) and are good for low-

cost applications. In general, a stepper motor will have high torque at low speeds, but low

torque at high speeds. Movement at low speeds is also choppy unless the drive hasmicrostepping capability. At higher speeds, the stepper motor is not as choppy, but it does not

have as much torque. When idle, a stepper motor has a higher holding torque than a servo

motor of similar size, since current is continuously flowing in the stepper motor windings.

3.2.2 Advantages of Stepper Motor

Some of the advantages of stepper motors over servo motors are as follows:

Low cost

Can work in an open loop (no feedback required)

Excellent holding torque (eliminated brakes/clutches)

Excellent torque at low speeds

Low maintenance (brushless)

Very rugged - any environment

Excellent for precise positioning control

No tuning required



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3.2.3 Disadvantages of Stepper Motor

Some of the disadvantages of stepper motors in comparison with servo motors are as follows:

Rough performance at low speeds unless you use micro stepping is used.

Consume current regardless of load

Limited sizes available

Noisy

Torque decreases with speed

Stepper motors can stall or lose position running without a control loop

3.2.4 Types of Stepper Motor

Three basic types of stepper motors include the permanent magnet motor, the variable

reluctance motor, and the hybrid motor, which is a combination of the previous two.

3.2.5 Theory of operation of Stepper Motor

Stepper motors provide a means for precise positioning and speed control without the use of

feedback sensors. The basic operation of a stepper motor allows the shaft to move a precise

number of degrees each time a pulse of electricity is sent to the motor. Since the shaft of themotor moves only the number of degrees that it was designed for when each pulse is

delivered, the pulses can be controlled that are sent and control the positioning and speed.

The rotor of the motor produces torque from the interaction between the magnetic field in the

stator and rotor. The strength of the magnetic fields is proportional to the amount of current

sent to the stator and the number of turns in the windings.

The stepper motor uses the theory of operation for magnets to make the motor shaft turn a

precise distance when a pulse of electricity is provided. It is known that like poles of a

magnet repel and unlike poles attract. Figure 3.2 shows a typical cross-sectional view of the

rotor and stator of a stepper motor. From this diagram it can be seen that the stator (stationary

winding) has four poles, and the rotor has six poles (three complete magnets). The rotor will

require 12 pulses of electricity to move the 12 steps to make one complete revolution.

Another way to say this is that the rotor will move precisely 30° for each pulse of



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Figure3.2 Diagram that shows the position of the six-pole rotor and four-pole stator of a

typical stepper motor. (Courtesy of Parker Compumotor Division.)

Figure 3.3 Movement of the stepper motor rotor as current is pulsed to the stator. (a) Current

is applied to the top and bottom windings, so the top winding is north, (b) Current is applied

to left and right windings, so the left winding is north, (c) Current is applied to the top and

bottom windings, so the bottom winding is north, (d) Current is applied to the left and right

windings so the right winding is north. (Courtesy of Parker Compumotor Division.)



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electricity that the motor receives. The number of degrees the rotor will turn when a pulse of

electricity is delivered to the motor can be calculated by dividing the number of degrees in

one revolution of the shaft (360°) by the number of poles (north and south) in the rotor. In

this stepper motor 360° is divided by 12 to get 30°.

When no power is applied to the motor, the residual magnetism in the rotor magnets will

cause the rotor to detent or align one set of its magnetic poles with the magnetic poles of one

of the stator magnets. This means that the rotor will have 12 possible detent positions. When

the rotor is in a detent position, it will have enough magnetic force to keep the shaft from

moving to the next position. This is what makes the rotor feel like it is clicking from one

position to the next as you rotate the rotor by hand with no power applied.

When power is applied, it is directed to only one of the stator pairs of windings, which will

cause that winding pair to become a magnet. One of the coils for the pair will become the

north pole, and the other will become the south pole. When this occurs, the stator coil that is

the north pole will attract the closest rotor tooth that has the opposite polarity, and the stator

coil that is the south pole will attract the closest rotor tooth that has the opposite polarity.

When current is flowing through these poles, the rotor will now have a much stronger

attraction to the stator winding, and the increased torque is called holding torque.

By changing the current flow to the next stator winding, the magnetic field will be changed

90°. The rotor will only move 30° before its magnetic fields will again align with the change

in the stator field. The magnetic field in the stator is continually changed as the rotor moves

through the 12 steps to move a total of 360°. Figure 3.3 shows the position of the rotor

changing as the current supplied to the stator changes.

In Fig. 3.3a it can be seen that when current is applied to the top and bottom stator windings,they will become a magnet with the top part of the winding being the north pole, and the

bottom part of the winding being the south pole. You should notice that this will cause the

rotor to move a small amount so that one of its south poles is aligned with the north stator

pole (at the top), and the opposite end of the rotor pole, which is the north pole, will align

with the south pole of the stator (at the bottom). A line is placed on the south-pole piece that

is located at the 12 o'clock position in Fig. 3.3a so that you can follow its movement as

current is moved from one stator winding to the next. In Fig. 3.3b current has been turned off

to the top and bottom windings, and current is now applied to the stator windings shown at



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the right and left sides of the motor. When this occurs, the stator winding at the 3 o'clock

position will have the polarity for the south pole of the stator magnet, and the winding at the

9 o'clock position will have the north-pole polarity. In this condition, the next rotor pole that

will be able to align with the stator magnets is the next pole in the clockwise position to the

previous pole. This means that the rotor will only need to rotate 30° in the clockwise position

for this set of poles to align it so that it attracts the stator poles.

In Fig. 3.3 c it can be seen that the top and bottom stator windings are again energized, but

this time the top winding is the south pole of the magnetic field and the bottom winding is the

north pole. This change in magnetic field will cause the rotor to again move 30° in the

clockwise position until its poles will align with the top and bottom stator poles. You should

notice that the original rotor pole that was at the 12 o'clock position when the motor first

started has now moved three steps in the clockwise position.

In Fig. 3.3d it can be seen that the two side stator windings are again energized, but this time

the winding at the 3 o'clock position is the North Pole. This change in polarity will cause the

rotor to move another 30° in the clockwise direction. You should notice that the rotor has

moved four steps of 30° each, which means the rotor has moved a total of 120° from its

original position. This can be verified by the position of the rotor pole that has the line on it,

which is now pointing at the stator winding that is located in the 3 o'clock position.

3.3 DC Motor

Industrial applications use dc motors because the speed-torque relationship can be varied to

almost any useful form. Direct-current motors transform electrical energy into mechanical

energy. They drive devices such as hoists, fans, pumps, calendars, punch-presses, and cars.

These devices may have a definite torque-speed characteristic (such as a pump or fan) or a

highly variable one (such as a hoist or automobile). The torque-speed characteristic of the

motor must be adapted to the type of the load it has to drive, and this requirement has given

rise to three basic types of motors:

1. Shunt motors

2. Series motors

3. Compound motors



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Direct-current motors are seldom used in ordinary industrial applications because all electric

utility systems furnish alternating current. However, for special applications such as in steel

mills, mines, and electric trains, it is sometimes advantageous to transform the alternating

current into direct current in order to use dc motors. The reason is that the torque-speed

characteristics of dc motors can be varied over a wide range while retaining high efficiency.

Today, this general statement can be challenged because the availability of sophisticated

electronic drives has made it possible to use alternating current motors for variable speed

applications. Nevertheless, there are millions of dc motors still in service and thousands more

are being produced every year.

3.3.1 Counter Electromotive force (CEMF)

Direct-current motors are built the same way as generators are; consequently, a dc machine

can operate either as a motor or as a generator. To illustrate, consider a dc generator in which

the armature, initially at rest, is connected to a dc source Es by means of a switch (Fig. 3.4).

The armature has a resistance R, and the magnetic field is created by a set of permanent

magnets.

As soon as the switch is closed, a large current flows in the armature because its resistance is

very low. The individual armature conductors are immediately subjected to a force because

they are immersed in the magnetic field created by the permanent magnets. These forces add

up to produce a powerful torque, causing the armature to rotate

On the other hand, as soon as the armature begins to turn, a second phenomenon takes place:

the generator effect. We know that a voltage Eo is induced in the armature conductors as

soon as they cut a magnetic field (Fig. 3.5). This is always true, no matter what causes the

rotation. The value and polarity of the induced voltage are the same as those obtained when

the machine operates as a generator. The induced voltage Eo is therefore proportional to the

speed of rotation n of the motor and to the flux F per pole, as previously given by Eq. 4.1:

Eo = ZnF/60 (1)

As in the case of a generator, Z is a constant that depends upon the number of turns on the

armature and the type of winding. For lap windings Z is equal to the number of armature

conductors.

In the case of a motor, the induced voltage Eo is called counter-electromotive force (cemf)



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because its polarity always acts against the source voltage Es. It acts against the voltage in the

sense that the net voltage acting in the series circuit of Fig. 3.5 is equal to (Es - Eo) volts and

not (Es + Eo) volts.

3.3.2 Acceleration of the motor

The net voltage acting in the armature circuit in Fig. 3.5 is (E s - E o) volts. The resulting

armature current /is limited only by the armature resistance R, and so

I = (E s - E o)IR (2)

When the motor is at rest, the induced voltage E o = 0, and so the starting current is

I = E s /R

The starting current may be 20 to 30 times greater than the nominal full-load current of the

motor. In practice, this would cause the fuses to blow or the circuit-breakers to trip. However,

if they are absent, the large forces acting on the armature conductors produce a powerful

starting torque and a consequent rapid acceleration of the armature.

As the speed increases, the counter-emf Eo increases, with the result that the value of ( E s —

E o) diminishes. It follows from Eq. 5.1 that the armature current / drops progressively as the

speed increases.

Although the armature current decreases, the motor continues to accelerate until it reaches a

definite, maximum speed. At no-load this speed produces a counter-emf E o slightly less than

the source voltage E s. In effect, if E o were equal to E s the net voltage ( E s — E o) would

become zero and so, too, would the current /. The driving forces would cease to act on the

armature conductors, and the mechanical drag imposed by the fan and the bearings would

immediately cause the motor to slow down. As the speed decreases the net voltage ( E s — E o)

increases and so does the current /. The speed will cease to fall as soon as the torque

developed by the armature current is equal to the load torque. Thus, when a motor runs at no-

load, the counter-EMF must be slightly less than E s so as to enable a small current to flow,

sufficient to produce the required torque.

3.3.3 Mechanical Power and Torque

The power and torque of a dc motor are two of its most important properties. We now derive

two simple equations that enable us to calculate them.



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Figure 3.4 starting a dc motor across the line.

Figure 3.5 Counter-electromotive force (CEMF) in a dc motor.



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According to Eq. 3 the CEMF induced in a lap-wound armature is given by

E o = ZnF/60 (3)

Referring to Fig. 3.5, the electrical power Pa supplied to the armature is equal to the supply

voltage E s multiplied by the armature current I :

Pa = E s I (4)

However, Es is equal to the sum of E o plus the IR drop in the armature:

E s = E o + IR (5)

It follows that

Pa = E s I

= ( E o + IR)I

= E o I + I 2 R (6)

The I 2 R term represents heat dissipated in the armature, but the very important term E o I is the

electrical power that is converted into mechanical power. The mechanical power of the motor

is therefore exactly equal to the product of the CEMF multiplied by the armature current

P = E o I (7)

Where

P = mechanical power developed by the motor [W]

E o = induced voltage in the armature (CEMF) [V]

/ = total current supplied to the armature [A]

Turning our attention to torque T, we know that the mechanical power P is given by the

expression

P = nT/9.55 (8)

where n is the speed of rotation.

Combining Eqs. 3,7, and 8, we obtain

nT /9.55 = E o I

= ZnFI/60

and so

T = Z F I /6.28

The torque developed by a lap-wound motor is therefore given by the expression



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T = Z F I /6.28 (9)

Where

T = torque [N×m]

Z = number of conductors on the armature

F = effective flux per pole [Wb]*

/ = armature current [A]

6.28 = constant, to take care of units

[Exact value = 2p]

Eq. 9 shows that we can raise the torque of a motor either by raising the armature current or

by raising the flux created by the poles.

3.3.4 Use of DC motors in AORS

Movement of y – axis and z – axis is achieved by the use of DC motors. The only difference

in both of the motors is that one of them controlling y – axis (upward and downward motion)

is 12 V DC, 3.5 amps 42 watt motor, while the other one handling z – axis motion is 14 V, 1

amps motor. Y – Axis motor is attached with a rotary encoder (explained later). Both motorsare connected to the controller via H – bridge circuit, identical in design, but with different

values of components.

DC motor is use for Z-Axis and its purpose to retrieve object, basically this DC motor is

coupled with the tray. When DC motor starts in clockwise direction tray is moved to forward

direction and in the end of tray limit switch is attached that indicate that tray is totally out,

limit switch is also use for feedback

3.4 Rotary Encoder

A rotary encoder, also called a shaft encoder, is an electro-mechanical device that converts

the angular position of a shaft or axle to an analog or digital code, making it an angle

transducer. Engineers use rotary encoders in many applications that require precise shaft

rotation — including industrial controls, robotics, expensive photographic lenses, computer

input devices (such as opto-mechanical mice and trackballs), and rotating radar platforms.

There are two main types: absolute and incremental (relative).



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Controlling systems for motor require measuring systems that provide feedback for the position and

speed controllers and for electronic commutation.

The two output wave forms are 90 degrees out of phase, which is all that the quadrature term means.

These signals are decoded to produce a count up pulse or a countdown pulse. For decoding in

software, the A & B outputs are read by software

3.5 Microcontroller

Atmel 89S52 has been used to control all the attached devices. Data sheet has been attached

to acquire any IC specific date as per requirement.

3.6 Key Pad

A keypad is a set of buttons arranged in a block which usually bear digits and other symbols

but not a complete set of alphabetical letters. If it mostly contains numbers then it can also be

called a numeric keypad. Keypads are found on many alphanumeric keyboards and on other

devices such as calculators, combination locks and telephones which require largely numeric

input.

In AORS a 3 x 3 matrix keypad is used. Numbers from 1 to 6 have been programmed for rack

number 1 to 6. Schematic of keypad used in the project and a generic one is as follows.

3.7 Stepper Circuit

This circuit serves as an interface between the stepper motor and the microcontroller.

Microcontroller generates the specific pulses, converts them into HEX code and transfers

them to its output pins where this stepper circuit is connected. TIP 122, the darlington pair

has been used.

The driver circuit must withstand the voltage and current required by the stepper motor. The

stepper motor which i used required 12volts and 1.5A to provide good torque, so i selected

using TIP122. Driver for each wire include a TIP122, a 1k ohm resistor and a diode. The

resistors are used for limiting the current and the diodes are used to avoid back EMF.

The common terminal of both the winding are shorted and connected to motor supply. When

logic 0 inputs is provided to the base of TIP122, the corresponding motor will remain floating

http://en.wikipedia.org/wiki/Alphanumeric_keyboard

http://en.wikipedia.org/wiki/Alphanumeric_keyboard



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3.6 Generic Keypad

Keypad used in AORS



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Figure 3.8 (Stepper Controlling Circuit)

Figure 3.9 (H-bridge)

Figure 3.10 (Bi-Directional H-Bridge)



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as the impedance between collector and emitter of TIP122 is very high. So no current flows

through that motor winding. When logic 1 input is provided to the base of the TIP122, its

collector and emitter get shorted as a result the motor wire will be grounded resulting in

current flow through the corresponding coil.

The driver circuit must withstand the voltage and current required by the stepper motor. The

stepper motor which i used required 12volts and 1.5A to provide good torque, so i selected

using TIP122. Driver for each wire include a TIP122, a 1k ohm resistor and a diode. The

resistors are used for limiting the current and the diodes are used to avoid back EMF.

The common terminal of both the winding are shorted and connected to motor supply. When

logic 0 input is provided to the base of TIP122, the corresponding motor will remain floating

as the impedance between collector and emitter of TIP122 is very high. So no current flows

through that motor winding. When logic 1 input is provided to the base of the TIP122, its

collector and emitter get shorted as a result the motor wire will be grounded.

If the stepper motor has a high current rating then it’s better to se TIP120/TIP121/TIP122 for

driving your stepper motor. The TIP122 is silicon epitaxial-Base NPN power transistor in

monolithic Darlington configuration mounted in TO-220 plastic package. It intended for use

in power linear and switching applications. Stepper circuit schematic is in the pages tofollow.

3.8 H – Bridge Circuit

Sometimes called a "full bridge" the H-bridge is so named because it has four switching

elements at the "corners" of the H and the motor forms the cross bar. The basic bridge is

shown below.

Of course the letter H doesn't have the top and bottom joined together, but hopefully the

picture is clear. The key fact to note is that there are, in theory, four switching elements

within the bridge. These four elements are often called, high side left, high side right, low

side right, and low side left (when traversing in clockwise order).

The switches are turned on in pairs, either high left and lower right, or lower left and high

right, but never both switches on the same "side" of the bridge. If both switches on one side

of a bridge are turned on it creates a short circuit between the battery plus and battery minus

terminals. This phenomenon is called shoot through in the Switch-Mode Power Supply



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(SMPS) literature. If the bridge is sufficiently powerful it will absorb that load and your

batteries will simply drain quickly. Usually however the switches in question melt.

To power the motor, you turn on two switches that are diagonally opposed. In the picture to

the right, imagine that the high side left and low side right switches are turned on. The current

flow is shown in green.

The current flows and the motor begins to turn in a "positive" direction. What happens if you

turn on the high side right and low side left switches? You guessed it, current flows the other

direction through the motor and the motor turns in the opposite direction.

Pretty simple stuff right? Actually it is just that simple, the tricky part comes in when you

decide what to use for switches. Anything that can carry a current will work, from four SPST

switches, one DPDT switch, relays, transistors, to enhancement mode power MOSFETs.

One more topic in the basic theory section quadrants, If each switch can be controlled

independently then you can do some interesting things with the bridge, some folks call such a

bridge a "four quadrant device" (4QD get it?). If you built it out of a single DPDT relay, you

can really only control forward or reverse. You can build a small truth table that tells you for

each of the switch's states, what the bridge will do. As each switch has one of two states, and

there are four switches, there are 16 possible states. However, since any state that turns both

switches on one side on is "bad" (smoke issues forth), there are in fact only four useful states

(the four quadrants) where the transistors are turned on.

High

Side

Left

High

Side

Right

Lower

Left

Lower

Right Quadrant Description

On Off Off On Motor goes Clockwise

Off On On Off Motor goes Counter-clockwise

On On Off Off Motor "brakes" and deceleratesOff Off On On Motor "brakes" and decelerates

The last two rows describe a maneuver where you "short circuit" the motor which

causes the motors generator effect to work against itself. The turning motor generates

a voltage which tries to force the motor to turn the opposite direction. This causes the

motor to rapidly stop spinning and is called "braking" on a lot of H-bridge designs.



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Figure 3.11 (H-Bridge for Y-Axis)

Figure 3.12 (H-Bridge for Y-Axis)



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Of course there is also the state where all the transistors are turned off. In this case the

motor coasts if it was spinning and does nothing if it was doing nothing.

The H – Bridge circuits for both dc motors are show in above page.

3.9 Oscillator Circuit

The function of an oscillator circuit is to provide an accurate and stable periodic clock signal

to a microcontroller. The frequency of this clock signal can range from a few kilohertz to tens

of megahertz and determines how quickly the microcontroller executes its instructions.

Most microcontrollers include a clock driver circuit which is designed to drive a quartz

crystal into oscillation.

3.10 Reset Circuit

Reset circuit is the most important part of a microcontroller. Reset circuit activates the

oscillating pulse in microcontroller only then crystal starts working and hence controller

starts working

In the power-down mode, the oscillator is stopped, and the instruction that invokes power-

down is the last instruction executed. The on-chip RAM and Special Function Registers

retain their values until the power-down mode is terminated. The only exit from power-down

is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. The

reset should not be activated before VCC is restored to its normal operating level and must be

held active long enough to allow the oscillator to restart and stabilize



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Figure 3.13 (Reset and the Oscillator Circuit)

Note: C1, C2 = 30 pF; 10 pF for Crystals= 40 pF; 10 pF for Ceramic Resonators



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CHAPTER 04AORS Working

4.1 Preamble

As already discussed previously AORS consists of the following main components:

A wooden shelf to place dummy materials

A steel structure carrying the shuttle to retrieve and place back the material

again.

A controller circuit to control the movement of shuttle in X, Y and Z axis.

A laptop / desktop computer to give commands. (The system can be

converted into an embedded system as it is controlled by a µ - controller.

Programming software to program the µ - controller for the three different

motors installed for the movement of shuttle.

Besides these components, the unit requires three power supplies to run three

different motors, specially the motor used to run the shuttle needs a high wattage

power supply to supply enough torque to lift the shuttle from an inactive position.

All these power supplies can be designed either on one module or separately as per

requirement, but for this prototype they have been selected separately as the focusof the project is not design of power supply rather the AORS itself.

4.2 Initialization of the System

AORS can be customized on need basis. Once the power supplies are switched on the

controller looks for the program (already burnt) and according to that initializes the shuttle.

This initialization sets all the three motors to (0, 0, and 0) position which is the lowest

position vertically, extreme left horizontally and farthest from the cabinets on z axis. These



28

positions can be changed offline as per requirement and the system can be initialized from

any desired location within the cabinet’s periphery.

4.3 Inputs/Output to and from the SystemThe inputs to the system have been programmed to a numeric keypad. Presently there are six

cabinets, so six of the nine push buttons have been programmed for each cabinet separately

with numbers 1 to 6. The rest of the buttons are used to initialize the system during online

condition. Presently the cabinet locations are known and the user based on its knowledge of

cabinet has to press the desired location button to reach the destination. In actual this can be

based on the component ID which is to be housed or taken from that location.

Recommendations to enhance the capability of the system have been made in the chapter tocome.

All the motors run in succession, i.e. once the movement in a particular axis is finished the

next movement starts. All motors can be made to run in parallel but in this particular case the

results are not much different from the sequential operation. The major reason is the size of

the cabinet which is not much big and hence no major difference in timing can be observed. It

may be noted however that the movement in Z axis should be the last as once the shuttle

reaches the desired cabinet number, only at that time the tray can be inserted.

4.4 Conclusion

The system was tested multiple times for various cabinet locations; minor bugs like

difference in calculation of exact length to move with respect to the number of rotations of

the chain pulley arrangement were removed. This was done by adjusting the links of the

chain used to pull the shuttle in different directions. Fluctuations in dc voltage levels were

looked upon by changing the power supply itself. The system is up and running in good

condition.



29

CHAPTER 05

Conclusions and

Future Recommendations

Nothing is perfect in this world and so is the case of AORS. Although much efforts have been

applied to make the system as robust as possible but rooms for improvement are always there

and are discussed as follows:

5.1 Power Supply

The very first recommendation for improvement is AORS indigenous power supply to cater

all sorts of requirements for the motor as well can combat well against the fluctuations,

flickers and other related problems.

5.2 Usage of better motors

As already discussed in above chapter, the precision/accuracy of the shuttle to reach the

desired location much depends on the least count of the stepper motor used. Normally the

term PWM is used to define the least count of the motor. Hence better the PWM better the

precision. One more aspect of better PWM is the advantage of electronics over mechanical

part. Minor adjustments are required on the mechanical part of the setup which is difficult as

compared to the electronic part.

5.3 SoftwareA lot of room is present to fill the gap in software side. A good database to maintain track of

the components in the shelve along with ID assignment on the basis of location. In this

manner, the shuttle can be moved to the desired location by the component and not the shelf

number. This is what is actually required. Although the requirement persuades to make the

size of the project bigger, needing a display requirement to look upon the component/s and

select the desired component.



30

5.4 Parallel running of motors

This needs the modification in assembly program to run the motors in parallel. As already

discussed the impact of this modification is can be well appreciated in large sized AORS.

5.5 Changing the desired location online

There is one more room of improvement in the assembly program as well. Assume a wrong

component is selected and the shuttle has started to move. Logic as well as sequence of

operation needs to be developed to cater these kind of cases.

Last but not least, building the same system on large scale even requires almost the same

level of efforts to build the circuitry, program the logic, etc. The larger size of the system

obviously needs large motors and as a result of that power electronic components, differentvoltage levels may be dc or ac, depending upon the requirement/s.

Control and Automation has been an area of interest since long and still sustain all the glitter

to attract any student/researcher to work in this area. AORS is the beginning with endless

possibilities to improve upon.



31

APPENDIX A

The Code

org 00h

sjmp KEY_PAD

mov p0,#00h

mov p1,#00h

mov p2,#0FFh

;------------------------------------Keypad----------------------------------------

KEY_PAD:

JUMP1: CLR P3.3

CLR P3.4

CLR P3.5

MOV A,P3

ANL A,#00000111B

CJNE A,#00000111B,JUMP2

LCALL DELAY2

JMP JUMP1

JUMP2: LCALL DELAY2

MOV A,P3

ANL A,#00000111B



32


JMP JUMP1

JUMP3: LCALL DELAY2

MOV A,P3

ANL A,#00000111B


JMP JUMP1

JUMP4: CLR P3.3

SETB P3.4

SETB P3.5

MOV A,P3

ANL A,#00000111B

CJNE A,#00000111B,COL_1

SETB P3.3

CLR P3.4

SETB P3.5

MOV A,P3

ANL A,#00000111B

CJNE A,#00000111B,COL_2

SETB P3.3

SETB P3.4

CLR P3.5

MOV A,P3



33

ANL A,#00000111B

CJNE A,#00000111B,COL_3

SJMP JUMP1

COL: JMP JUMP4

COL_1 : CJNE A,#00000110B,COL_1A

SJMP box1

COL_1A: CJNE A,#00000101B,COL_1B

SJMP box2

COL_1B: CJNE A,#00000011B,JUMP4

SJMP box3

COL_2: CJNE A,#00000110B,COL_2A

SJMP box4

COL_2A: CJNE A,#00000101B,COL_2B

SJMP box5

COL_2B: CJNE A,#00000011B,JUMP4

JMP stepper_b

COL_3: CJNE A,#00000110B,COL_3A

SJMP stepper_f

COL_3A: CJNE A,#00000101B,COL_3B ;jump to stop

SJMP y_dc_b

COL_3B: CJNE A,#00000011B,JUMP4 ;jump to box 3

SJMP y_dc_f

;---------------------------Keypad Tasks------------------------------------------



34

box1: mov r7,#100d

mov a,r7

mov r2,a

mov r6,#30d

mov r5,#15d

mov r4,#1d

mov a,r4

mov r3,a

ljmp stepper

box2: mov r7,#15d

mov a,r7

mov r2,a

mov r6,#30d

mov r5,#15d

mov r4,#2d

mov a,r4

mov r3,a

ljmp stepper

box3: mov r7,#100d

mov a,r7

mov r2,a

mov r6,#30d



35

mov r5,#15d

mov r4,#2d

mov a,r4

mov r3,a

ljmp stepper

box4: mov r7,#15d

mov a,r7

mov r2,a

mov r6,#30d

mov r5,#15d

mov r4,#3d

mov a,r4

mov r3,a

ljmp stepper

box5: mov r7,#100d

mov a,r7

mov r2,a

mov r6,#30d

mov r5,#15d

mov r4,#3d

mov a,r4

mov r3,a

jmp stepper



36

stepper_b: jmp rot_stpr_b

stepper_f: jmp rot_stpr_f

y_dc_b: jmp y_dc_start_b

y_dc_f: jmp y_dc_start_f

;---------------------------X-Axis Stepper ---------------------------------------

stepper: djnz r7,rot_stpr

ljmp y_dc_start

rot_stpr: mov p2,#0F6h

acall delay

mov p2,#0FFh

mov p2,#0FCh

acall delay

mov p2,#0FFh

mov p2,#0F9h

acall delay

mov p2,#0FFh

mov p2,#0F3h

acall delay

mov p2,#0FFh

jmp stepper

;---------------------------Y-Axis DC Motor---------------------------------------

y_DC: djnz r4,here

jmp here3



37

y_dc_start: mov p2,#0BFh

here: jnb p1.0,here

here2: jb p1.0,here2

jmp y_DC

here3: mov p2,#0FFh

SJMP z_rotate

;---------------------------Z-Axis DC Motor------------------------------------------

z_rotate: mov p2,#0DFH

CALL DELAY_3

h_1: jb p1.3,stp_z_dc

JMP h_1

stp_z_dc: mov p2,#0FFh

jmp y_dc_up_start

;---------------------------Z-Axis DC Motor------------------------------------------

y_dc_up: djnz r6,here_up

jmp here3_up

y_dc_up_start: mov p2,#0BFh

here_up: jnb p1.1,here_up

here2_up: jb p1.1,here2_up

jmp y_dc_up

here3_up: mov p2,#0FFh

jmp z_rotate_r

;---------------------------Delay For Motors---------------------------------------



38

z_rotate_r: mov p2,#0EFH

CALL DELAY_3

h_1_r: jb p1.3,stp_z_dc_r

JMP h_1_r

stp_z_dc_r: mov p2,#0FFh

jmp y_dc_start_r

;---------------------------Delay For Motors---------------------------------------

y_DC_r djnz r3,here

y_DC_r: djnz r3,here_r

jmp here3_r

y_dc_start_r: mov p2,#07Fh

here_r: jnb p1.0,here_r

here2_r: jb p1.0,here2_r

jmp y_DC_r

here3_r: mov p2,#0FFh

jmp y_dc_down_start

;---------------------------X-Axis DC Motor Rev-----------------------------------

y_dc_down: djnz r5,here_down

jmp here3_down

y_dc_down_start: mov p2,#07Fh

here_down: jnb p1.1,here_down

here2_down: jb p1.1,here2_down

jmp y_dc_down



39

here3_down: mov p2,#0FFh

jmp stepper_r


stepper_r: djnz r2,rot_stpr_r

ljmp key_pad

rot_stpr_r: mov p2,#0F3h

acall delay

mov p2,#0FFh

mov p2,#0F9h

acall delay

mov p2,#0FFh

mov p2,#0FCh

acall delay

mov p2,#0FFh

mov p2,#0F6h

acall delay

mov p2,#0FFh

jmp stepper_r


rot_stpr_b: mov p2,#0FFh

mov p2,#0FCh

acall delay

mov p2,#0FFh



40

mov p2,#0F6h

acall delay

mov p2,#0FFh

mov p2,#0F3h

acall delay

mov p2,#0FFh

mov p2,#0F9h

acall delay

mov p2,#0FFh

jmp key_pad

rot_stpr_f: mov p2,#0FFh

mov p2,#0F6h

acall delay

mov p2,#0FFh

mov p2,#0FCh

acall delay

mov p2,#0FFh

mov p2,#0F9h

acall delay

mov p2,#0FFh

mov p2,#0F3h

acall delay

mov p2,#0FFh



41

jmp rot_stpr_f

;---------------------------Delay For Motors---------------------------------------

y_dc_start_b: mov p2,#07Fh

acall delay_3

acall delay_3

mov p2,#0FFh

jmp key_pad

y_dc_start_f: mov p2,#0BFh

acall delay_3

acall delay_3

mov p2,#0FFh

jmp key_pad

;---------------------------Delay For Motors---------------------------------------

delay: mov r0,#6

lp0: mov r1,#255

lp1: djnz r1,lp1

djnz r0,lp0

ret

;---------------------------Delay For Keypad-----------------------------

delay_3: mov r0,#220

lp0_3: mov r1,#255

lp1_3: djnz r1,lp1



42

djnz r0,lp0

ret

;---------------------------Delay For Keypad---------------------------------------

DELAY2: MOV TL0,#00H

MOV TH0,#0FFH

SETB TR0

TIMER2: JNB TF0,TIMER2

CLR TR0

CLR TF0

RET

END



43

AT89S52 Data Sheet



44

A1383 Data Sheet



45

AN3001 Data Sheet

Application Note AN-3001



46

C673 Data Sheet



47

LTV4N25 Data Sheet



48

TIP 35A Data Sheet



49

TIP 36 Data Sheet



50

TIP 122 & 127 Data Sheet



51

References

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6. http://www.motorola.com/Business/PK-

EN/Business+Solutions/RFID+Warehouse+Distribution+Solutions_Loc:XU-

EN,XN-EN,XC-EN,XM-EN,XE-EN,PK-EN,XF-EN

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Mongkut's Inst. of Technol., Bangkok, Thailand This paper appears in: TENCON 2004. 2004

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appears in: System Sciences, 2004. Proceedings of the 37th Annual Hawaii International

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stochastic optimization Archetti, F. Schiomachen, A. Gaivoronski, A. Milano Univ., Italy;This paper appears in: Petri Nets and Performance Models, 1991. PNPM91., Proceedings of

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Te Chen Jui-Yu Cheng Rui-Wen Ho Gong Chen Dept. of Electr. Eng., Nat. Defense

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Shuqin Wang Lindu Zhao Inst. of Syst. Eng., Southeast Univ., Nanjing This paper

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