Vending Machines Come In Different Types

Published Date: 02 Nov 2017

CHAPTER 1

INTRODUCTION

Background of Study

As people continue to seek for convenience, more and more technologies are invented. One of these technologies is the vending machine. Vending machines come in different types as they are made for different purposes. Vending Machines are rarely found in the market of Egypt and its industry hasn’t been made yet in addition to the increasing consumption of instant noodles within different ages of people made the idea of designing & implementing an instant noodles vending machine the availability of investing in a new virgin field with the knowhow of mechatronics can help in making this project a successful and a practical realistic one. Before starting with details of the proposed project, we will first talk about some facts and history about variety of vending machines (Sabek 2012).

Vending machine is a coin operated machine for selling merchandise (Merriam Webster Dictionary). Vending machine provides various product such as snacks, beverages, water, tickets, and others product. Vending machine has many benefits such as no need human energy, flexible in time, and saving time (Amar 2008)

The term ‘vend’ is defined as "to be disposed of by sale". Items that are capable of being vended are thus referred to as ‘vendibles’. This means that any items or services that can be sold can be considered as possible vendibles. Groceries, snacks, fuel, ATMs, bookings for almost any kind of service and orders for almost any kind of goods: could all be considered "vendibles" (Tony 2001)

Problem Statement

From the previous project background, the problem that the project wants to solve is the problem with the payment method. The method used now is using a coin and note money. The problem with the payment is the tank full with a coin the notes cannot be read and also the notes or coin always stuck in the machine (Tony 2001).

Firstly, problems occur for vending machine in tank area. When the tank was full, no more coin can be accepted. This will cause no more purchase can be made thus vending machine will stop the operated.

Secondly, the problem with the notes cannot be read. For vending machine using notes as method payment, the notes must be in good condition. The term of good condition refer to the good shape of the notes, not folded, and original one. When using notes with bad condition such as crumpled and dirty, the vending machine cannot read the note and then rejected the payment.

Lastly, the problems occur when notes or coin stuck in machine. Actually when the coin or the notes inserted not in the right direction, this problem will occur. The only way to remove the notes or coin stuck is called the vending machine company to repair that machine (Amar 2008), ("Interview" 2006) and (Tony 2001).

As conclusion with the current method of payment, there are many problem occurs. So, this project will develop a new system for vending machine that uses prepaid method.

Aim and Objectives

1.3.1 Aim

The aim of the project is to design and develop microcontroller based cold drink vending machine.

1.3.2 Objectives

1- To design the converter circuit for the operation of motor.

2- To create the program for controlling the converter operation based on the sensual signal.

Scope of the Study

The scope of the study is to develop a vending machine which will aid people who are engaged in the prepaid reloading industry by automating the conventional method being practiced even as we speak. This thesis project will help distributors avoid, or even eliminate the tedious task of inputting the mobile phone number and the amount to be reloaded which is, in most cases, where the error cause by negligence occurs. There will be room for franchise expansion since the thesis will then have a corresponding hardware, the device made can be placed anywhere. Similar to a vending machine, this device will be a standalone prepaid reloading machine. It will further expand the horizon of business entrepreneurs by placing this.

Report structure

The Automatic Cold Drink Vending machine project will cover a lot of chapters and they can be summarized as follows:

Chapter one is basically the introduction of the entire project. It gives the general overview of the entire project. It presents to the reader the main reasons for undertaking the project, objectives, possible application in real life time and the problem statement.

Chapter two, reviews the works of other researchers that has been done in relation to the entire project, and discussing how these related technologies have not been fully effective and where the advantages of this project plays a vital role.

Chapter three, this chapter explains the block diagram, circuit diagram, and the entire concept of the expected project and specifications of the components that are going to be implemented in the project.

Chapter four presents the designs and the procedures used to develop the hardware and software of the system; it also shows the testing and implementation of work done. Development of software and flowcharts are discussed in this chapter. It also involves calculations simulations and practical testing of the circuits.

Chapter five of the project is the implementation of data and results. The observation of the designs and results obtained are critically analyzed. The flaws and perfection of the designs are also discussed in this chapter.

Chapter six is the last and the final chapter; it concludes whether the proposed system and the project have fully met its aim and objectives. Nevertheless, if aim and objectives of the project is not met, explanations are given with supported theory and explanation for its failure. The chapter also covers suggestion and recommendation to improve further related works.

CHAPTER 2

LITERATURE REVIEW & THEORETICAL BACKGROUND

2.1 Introduction

This chapter will explain about the development of the vending machine. This chapter also contain about the previous research on vending machine payment method. In the end of this chapter, the payment method for the vending machine will be discussed. The chapter will be mainly divided in to two parts first the Literature review and the the theoretical background of the study.

2.2 Literature review

In this section we shall discuss about the significant of the vending machine by investigating its history and then by reviewing the work of previous scholars and engineers to update on the present state of the system to verify its development and aim that should be achieved by our project.

2.2.1 Definition

Definition for vending machine is a coin operated machine for selling merchandise. Vending machine provides various product such as snacks, beverages, water, tickets, and others product. Vending machine also no need operator or workers to operated it.

Vending machine has two functions that are selling the product and sell the service to the customers. Vending machine will sell the product that install into the body with different type of product and price. After paying, a product may become available by the machine releasing it at the bottom of the vending machine. For the vending machine that provide service for the main function, the service also may become available after paying with inserted the payment. Example for the services vending machine is Money ATM vending machine Amar (2011).

2.2.2 History of Vending Machine

About 215 B.C, the first vending machine is believed to have been invented in Alexandria, Egypt. The mathematician Hero introduced machine that accepted a coin and then dispensed a fixed amount of holy water. After that, in A.D1076, vending machine was updated by Chinese inventors that developed a coin-operated pencil vendor.

Early 1880s, the first modern coin-operated vending machines that dispensing post card were introduced in London, England. The first vending machine in the U.S. was built in 1888 by the Thomas Adams Gum Company. The vending machine dispensed a piece of tutti-frutti gum.

In late 1920 and 1930, higher price installed into the vending machine was introduces. Example for the product that been sold in the vending that time is soft drink and nickel-candy. In 1946, coffee vendors were developed and followed by refrigerated sandwich vendors in 1950 Tony (2001).

Nowadays, many items can be found in vending machine such as clothing, milk, cigarettes, postage stamps, cologne, baseball cards, books, live bait, comic books, and many more. Some hi-tech vending machine can dispense hot foods such as pizza, popcorn, French and burger.

2.2.3 Related Projects and Journals on Vending Machine

The author Roger (2008) stated that in there paper they describes an experimental Java client server system and a special purpose hardware interface to control a Pepsi B vending machine over the World Wide Web. This system allows users with pre-paid accounts to vend a soda from the Pepsi A machine (without any coins or bills) using a web browser such as Netscape or Internet Explorer. Anyone with a web browser may find out if any of his or her favorite sodas are left in the machine. The server software can also notify the vending corporation, via Internet email, when each brand of soda needs to be restocked. The software includes a Java applet (the client) and a multi-threaded Java server. The computer system, an Intel based Linux machine, runs its own web server at http://pepsi.millersv.edu/ and is physically located inside the Pepsi B machine.

However the team was able to described an experimental Java client server system and a special purpose hardware interface to control a Pepsi B vending machine over the World Wide Web. This system allows users with pre-paid accounts to vend a soda from the Pepsi B machine (without any coins or bills) using a web browser such as Netscape or Internet Explorer. Anyone with a web browser may find out if any of his or her favorite sodas are left in the machine. The Java server cannot the vending corporation, via email, when each soda needs to be restocked. A special purpose hardware built at Millersville University, to interface to the Dixie-Narco vending computer inside the Pepsi B machine has also been described.

In this paper the author describes about LCA (Life Cycle Assessment) ",which can assess the environmental aspect and potential impact associated with a product ‘yrom the cradle to the grave " synthetically, has become noteworthy. The sofmare "MieLCA ", which can be operated easily on the personal computer to conduct LCA-NETS (Numerical Eco-Load Total Standardization) was composed by employing LCA method "ESS" (Eco- Load Standardization System) proposed by the author’s group. The assessment of various kinds of the industrial products can be performed applying "MieLCA ". On the other hand, the Vending Machine has something to do with the environment in a same extent with the other industrial products. At this time, in addition to conducting such assessment, the ecological improvement was performed taking account of the concept of re-use etc. As a case study, the evaluation of environmental performance of vending machine.

As conclusion In this paper we have introduced the LCA scheme with the aid of the ESS method as a numerical measure to estimate the quantitative load of any industrial activity and products on environmental due to resources’ depletions, global warming ozone layer depletion, water and air pollution, rain acidification, and waste processing. And we develop Software "MieLCA" which estimates various industrial products and analysis from various aspects by using this ESS, and estimated vending machines using it. As a result, it was confirmed that "MieLCA" could contribute an environmental tool, and "Reusing" is very effective on environmental load reduction and cost. Reusing is most important in the development of future vending machines Kimura (2001).

This paper addresses a mobile payment solution where there is no connection required for the vending machine, and while the local means of communication is through infrared (IR). It is assumed that the cellular phone has the IR feature. All the user has to do is to select the item, and point the infrared enabled cellular phone to the vending machine. The vending machine will detect the presence of the cellular phone through IR, and the communication will take place by sending a message to the back-end server. Detailed inventory and telemetric information can be added to the transaction data. A data compression, segmentation and reassembly scheme was implemented.

In conclusion they propose a system that provides a new means of payment for non-connected points of sales, mainly targeted to small amount transactions, such as vending machines, parking meters and urban transportation Seyed (2004)

Here the authors Hong (2008) have done a project on A wireless vending machine system based on the GSM network is developed in this paper. First of all, several methods by which we may realize wireless data communication of GSM network are analyzed and compared, the overall structure of vending machine system based on USSD is given an in-depth introduction. Furthermore, control modules which realize data transmission and control function of terminal device, middleware which connects application and BOSS (business operation support system), and transaction software embedded in USSD platform, are also developed respectively. Finally, the operating support system of wireless vending machine system is formed, which can not only integrate vending machines, USSD platform and payment system together, but also manage sale information, logistic information and consumer information on-line.

In conclusion the group was able to successfully finish vending machine system presented in this paper has been put into use in several provinces and cities for more than two years. All performance indexes of the system are satisfying.

In this project the author writes about a Single Electron Devices (SED) are promising for future ULSI technology because of their ultra-low power consumption, higher density of integration and switching speed. Structure of SED is based on the discrete nature of electrons tunneling through thin potential barriers. The ultimate goal of this work is to venture one possible way of using electron-tunneling devices instead of conventional MOS transistors to design and simulate an automatic tea/coffee vending system. The proposed vending machine will establish a good approximation for the limits and challenges that ever-shrinking circuits will meet eventually, when the size of the components become comparable to that of electrons.

In conclusion the design and simulation provided accurate results thereby making it a promising candidate for future ultra-dense integrated circuit based low power consuming system. This system will provided a good approximation for the limits and challenges that ever-shrinking circuits will face, eventually, when the size of the components become comparable to that of electrons Clement (2007).

This paper presents a method for monitoring activities at a ticket vending machine in a video-surveillance context. Rather than relying on the output of a tracking module, which is prone to errors, the events are directly recognized from image measurements. This especially does not require tracking. A statistical layered approach is proposed, where in the first layer, several sub-events are defined and detected using a discriminative approach. The second layer uses the result of the first and models the temporal relationships of the high level event using a Hidden Markov Model (HMM).

In Conclusion we have presented an event recognition based approach for monitoring ticket vending machines. A model for detecting high level events with a layered architecture has been presented. The high level event is composed of several sub-events, which are detected by SVM. These sub-events are also of interest and can provide useful information to monitor the station’s activity. Classification results for the queuing event show that the layered approach outperforms a baseline one with raw features, but still need improvement. A more constrained architecture of the HMM could help to discriminate the queue events Xavier (2008).

In this paper the author Fauzihan (2009) frozen foods are well-known among Malaysia society. This is due to the modern lifestyles which require short food preparing times without neglecting the food nutritious. In supporting this requirement, the manipulation of vending machine is identified as a tool to promote modern and healthy living style, besides to simplify the cooking process. In this paper they describes the effort on designing conceptual model for a proposed steaming food vending machine simulator.

In conclusion to promote modern, yet healthy living style, they discussed the initial stage on constructing the conceptual model for steaming frozen food (steamed bun) in vending machine. The model is constructed based on combination of process oriented approach and process flow (or control) logic. The next stage of this study is to covert the conceptual model into simulation modeling using simulation software to get the optimum water level for the steaming purposes and total serving time for the steamed buns.

In this paper proposes a software integration model of service component architecture in the vending industry. They use this architecture to rapidly integrate related services, substantially reduce development costs, establish innovative services, and provide consumers with a brand new experiential shopping environment in retail domain. Meanwhile, we apply a cloud computing technology to solve the following problem service over loading in a distributed environment. They also discover many issues that will happen with system scaling up in smart store, such as virtual integration, location-based shopping service, personal services, and product optimization. Therefore we use cloud computing to solve these discussed issues.

Finally, this paper gives two services as an example to be implemented in the vending industry. The research provides a cloud-based integration system that composes other services easily. The results of this research can increase development speed, and decrease poorly-done work over again and time consumption. It also makes allowance for system stability and scalability Feng (2009).

In this paper the author speaks with respect to japan where he brings statistics more than 5 million of vending machines were so far installed in Japan. The quantity per head is the top in worldwide. One important factor of this success is that public security in Japan is well in force and that makes us possible to install vending machines on the street corner without concern for crime. As a result, unique "vending machine culture" to Japan was established. Recently, this vending machine culture is changing its phase from a simple "convenient unmanned shop" to a station providing several services such as a) various kinds of information b)food supply to disaster area c) support to emergency patients d) security service for outskirts etc.

This paper makes an introduction of these unique services to public and local society provided with vending machines and discusses future possibilities towards advanced vending machine service culture. Toshio (2010).

The author presents a design of vending machine based on the short massage payment with the main control module M68HC11 and GPRS module MC35 has been illustrated. This paper describes the working program of the system and especially the MDB bus and photoelectric conversing circuit and MC35 module are presented. A structure of vending machine is designed, the hardware ideas of bus conversion interface, the software protocol rules based on AT command and the way to use short message payment are given out.

In conclusion The system completes the short message payment by adopting M68HC11 and MC35 and makes it have the function of the short message shopping and make it easy to use and manage. It has simple structure, good reliability, strong ability of processing, low cost, the function being extended easily, the simple and practical way in application Zhang (2010).

In this paper we propose an implementation technique for sequential circuit using single electron tunneling technology (SET-s) with the example of designing of a "coffee vending machine" with the goal of getting low power and faster operation. We implement the proposed design based on single electron encoded logic (SEEL).The circuit is tested and compared with the existing CMOS technology.

In conclusion a real-time replenishment system for vending machine industry is proposed. The aim of the system was to ormulate feasible replenishment plan so as to enhance the customer satisfaction. It provides the real-time information sharing ability between the vending machines and centralized database of the vending machine companies. When the data of sales and inventory of the vending machines are captured by the counter installed inside the vending machines, they can be sent out to the centralized database by the GPRS sending device so that the company can obtain the useful information for formulating replenishment plan without visiting the vending machines. Through the simulation tests, the objective of minimizing the transportation and stock out costs is achieved Poon (2010).

Here the author Haim (2011) presented the paper on the study source coding in the presence of side information, when the system can take actions that affect the availability, quality, or nature of the side information. We begin by extending the Wyner-Ziv problem of source coding with decoder side information to the case where the decoder is allowed to choose actions affecting the side information. We then consider the setting where actions are taken by the encoder, based on its observation of the source.

In conclusion the actions may have costs that are commensurate with the quality of the side information they yield, and an overall per-symbol cost constraint may be imposed. We characterize the achievable tradeoffs between rate, distortion, and cost in some of these problem settings. Among our findings is the fact that even in the absence of a cost constraint, greedily choosing the action associated with the "best" side information is, in general, suboptimal.

In this paper, the authors compared three stock-out policies in vending machine systems, which are the no stock-out allowance policy, stock-out policy allowing only give-ups, and stock-out allowance policy, by constructing the respective mathematical models for determining the item allocation to storage compartments and replenishment intervals of vending machines. We performed computational experiments on a test problem in order to evaluate the effectiveness of the three policies with respect to system profit. The results showed the substantial advantage of the stock-out allowance policy over the other two policies.

This paper compared three stock-out policies in vending machine systems, which are the no stock-out allowance policy, stock-out policy allowing only give-ups, and stock-out allowance policy, by constructing the respective mathematical models for determining the item allocation to storage compartments and replenishment intervals of vending machines Yang (2011).

The model of side information "vending machine" accounts for scenarios in which acquiring side information is costly and thus should be done efficiently. In this paper, the three-node cascade source coding problem is studied under the assumption that a side information vending machine is available either at the intermediate or at the end node. In both cases, a single-letter characterization of the available trade-offs among the rate, the distortions in the reconstructions at the intermediate and at the end node, and the cost in acquiring the side information are derived under given conditions.

In conclusion in this project the Cascade source coding models capture important aspects of multi hop networks with correlated sources. This work was studied two classes of cascade models in which the quality of the available side information can be controlled via actions taken by the nodes. Many problems remain open such as characterizing the performance of the system Behzad (2012).

2.3 Theoretical Background

In this section we shall discuss about the peripherals of the Automatic Cold Drink Vending machine. Where we mainly discuss about the processing unit of the project the Microcontroller and its architecture, clock generator validator and RS 232 standard.

2.3.1 Microcontroller

Microcontroller is a computer-on-a-chip used to control electronic devices. It is atype of microprocessor emphasizing self-sufficiency and cost-effectiveness ("Microcontroller", 2006). It is a highly integrated chip that contains all the components comprising a controller. Typically, this includes a CPU, RAM, some form of ROM, I/O ports, and timers. Unlike a general-purpose computer, which also includes all of these components, a microcontroller is designed for a very specific task – to control a particular system. As a result, the parts can be simplified and reduced, which cuts down on production costs.

2.3.2 CPU (Central Processing unit)

It is a component in computers which interprets instructions and processes data contained in computer programs. The CPU is the brains of the computer. Sometimes referred to simply as the processor or central processor, the CPU is where most calculations take place. In terms of computing power, the CPU is the most important element of a computer system.

2.3.3 Input/output Interface

It is the collection of interfaces that different functional units (sub-systems) of an information processing system use to communicate with each other, or the signals (information) sent through those interfaces. Inputs are the signals received by the unit, and outputs are the signals sent from it. I/O devices are used by a person (or other system) to communicate with a computer. For instance, keyboards and mice are considered input devices of a computer and monitors and printers are considered output devices of a computer. Typical devices for communication between computers are for both input and output, such as modems and network cards ("Input/output", 2004)

2.3.4 Peripheral Devices

It is a type of computer hardware that is added to a host computer in order to expand its capabilities. More specifically the term is used to describe those devices that are optional in nature, as opposed to hardware that is either demanded, or always required in principle ("Peripheral", 2006).A peripheral is any computer device that is not part of the essential computer but is situated relatively close by. Some peripherals are mounted in the same case with the main part of the computer, as are the hard disk drive, CD-ROM drive, and NIC. Other peripherals are outside the computer case, such as the printer and image scanner, attached by a wired or wireless connection.

2.3.5 RAM (Random Access Memory)

The most common computer memory which can be used by programs to perform necessary tasks while the computer is on; an integrated circuit memory chip allows information to be stored or accessed in any order and all storage locations are equally accessible

2.3.6 ROM (Read Only Memory)

A class of storage media used in computers and other electronic devices. Because it cannot be written to, its main uses lie in the distribution of firm ware ("Read-only memory", 2006). It is a memory whose contents can be accessed and read but cannot be changed.

2.3.7 Clock generator

It is a circuit that produces a timing signal (known as a clock signal and behaves as such) for use in synchronizing a circuit's operation. It can range from a simple symmetrical square wave to more complex arrangements. The basic part that all clock generators share is a resonant circuit and an amplifier ("Clock generator", 2006).

2.3.8. Bill Acceptor / Validator

A bill acceptor validates paper currency and then sends a corresponding I/O signal to its output connector. It doesn't give change, validate coins or scan magnetic cards. Bill acceptors are found in vending and gaming machines, amusements, gasoline pumps, drop safes, automated payment systems and Internet kiosks. A bill acceptor typically contains between five to 20 optical sensors such as LEDs and/or magnetic sensors.

These sensors read data points off the bill, which are then digitized and compared with internal currency recognition software for validation. It is a component of electronic vending machines and other devices that accept paper currency. They were introduced in the U.S. in the early 1980s. While in the past, these devices were extremely susceptible to failure and jamming due to folded or damaged notes, they have improved remarkably in recent years and now include such features as automatic jam ejection and automatically calibrating sensors. Cleaning cards are available to remove contaminants from the machines ("Bill validator", 2006).

2.3.9 RS232 Standard

RS-232 is a standard for serial binary data interconnection between a DTE (Data terminal equipment) and a DCE (Data communication equipment). It is commonly use din computer serial ports. The Electronic Industries Alliance (EIA) standard RS-232-C as of 1969 defines:

Electrical signal characteristics such as voltage levels, signaling rate, timing and slew-rate of signals, voltage withstand level, short-circuit behavior, maximum stray capacitance and cable length

Interface mechanical characteristics, pluggable connectors and pin identification

Functions of each circuit in the interface connector

Standard subsets of interface circuits for selected telecom applications The standard does not define such elements as character encoding (for example, ASCII, Baudot or EBCDIC), or the framing of characters in the data stream (bits per character, start/stop bits, parity). The standard does not define bit rates for transmission, although the standard says it is intended for bit rates less than 20,000 bits per second. Many modern devices can exceed this speed (38,400 and 57,600 bit/s being common, and115,200 and 230,400 bit/s making occasional appearances) while still using RS-232compatible signal levels ("RS-232", 2006).

2.3.10 Personal Error

Personal Errors may arise from a personal bias of the observer in reading an instrument, in recording an observation, or his particular method of taking data, As well as mistakes in mathematical calculations. Example of this error is the taking of incorrect values from the measuring instruments caused by not looking at the screen at a perpendicular angle. This may also be called Parallax Error (Fontanilla, 2002).

CHAPTER 3

SYSTEM DESIGN

3.1 Introduction

In this chapter we explain the system block diagram, circuit diagram, and the entire concept of the expected project and specifications of the components that are going to be implemented in the project.

3.2 System block diagram

The system block diagram of the "Automatic Cold Drink Vending machine" is revolving around the micro controller. In this project we use 16F877A for its high performance and Analog to digital converter port. Here the consumer user will enter the user name and password to the system, and the microcontroller will detect the input and verify the consumer account and will provide the detail in the LCD screen as to the consumer, so that will be able to select the amount beverages per serving.

When the initial selection is made though the key pad the system will detect and start pouring the drinks to the container. Here we use the light dependent resistor the LDR to detect the fluid level in the container and avoid from over flow. As the drink is served in one container the AC motor will activate and shift the table so that the next filling continues when the filling competes for the required serving the buzzer switch will go on to notify the consumer his/her beverages is ready.

Figure 3.1 system design of the "Automatic Cold Drink Vending machine"

In the above figure 3.1 we see the block diagram of the Automatic Cold Drink Vending machine where the complete system revolve around the microcontroller and the input units are Key pad and opto slotted switch and the outputs are status LED, LCD and BUZZER. The AC motor, relay valve and the LDR are decision making units of the system.

3.3 Power supply

The power supply is the main power source of the system where it will provide a rectified DC voltage of 5V and 12V to the components of the system Each power supply consists of four phase controlled half-wave converters. Each of the two half-wave converters are connected through inter phasing transformers to obtain a full-wave bridge with 120" conduction.

The input voltage for these two half-wave bridges are 60' apart. In order to obtain the high voltage needed for the load, two of the full-wave bridges are connected in series. This action not only provides the required voltage, it also improves the power factor of the power supply. The output of the bridges is filtered through a passive L-CR filter to meet the current ripple limit requirement. In order to ramp the current in the load, the conduction angle of the power supply is varied.

In order to keep the bridge conducting continuously, a small circulating current in the bridge is needed. For this purpose a diode with a resistor in series, is connected in parallel with each bridge.

3.4 Microcontroller

Here we use the 16F877A PIC microcontroller, a micro-controller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory is in the form of RAM (Random access memory). Micro-controllers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications.

Micro-controllers are used in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, remote controls, office machines, appliances, power tools, toys and other embedded systems. By reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, micro-controllers make it economical to digitally control even more devices and processes.

Mixed signal micro-controllers are common, integrating analog components needed to control non-digital electronic systems. PIC is a family of modified Harvard architecture micro-controllers made by Microchip Technology. The name PIC initially referred to "Peripheral Interface Controller". Pics are popular with both industrial developers and hobbyists alike due to their low cost, wide availability, large user base, extensive collection of application notes, availability of low cost or free development tools, and serial programming (and re-programming with flash memory) capability.

The PIC32 architecture Pros

• The highest execution speed

• The large flash memory: 512 k Byte

• One instruction per clock cycle execution

• The first cached processor

• Allows execution from RAM

The PIC32 architecture Cons

• Possibility of damaging the PIC during code burning is high.

• Number of input/output pins available is limited.

• The max current the PIC can withstand is relatively low compared to PLC and Adriano micro-controllers.

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Figure 3.2 16F877A PIC microcontroller

3.5 AC Motor

Is a simple electric motor which uses electricity and a magnetic field to produce torque that results in turning of the motor. Simply, a DC Motor requires an electric coil and two of opposite polarity magnets in which attraction and repulsion causes rotation of the motor in a certain direction. DC Motors can be found in applications like electric razors, remote control cars and electric car windows.

Here we use a One DC Motor with Encoder and Gear for the fork dispenser mechanism that dispenses a fork to the customer being served. This DC Motor is selected on the basis of simple On/Off operation during a certain period of delay time. The Motor shaft is fitted to an extension which carries a Spring filled with forks ready to be served such that each complete rotation translates linearly a fork and dispenses it to the customer. The configuration of the motor is given in the table 3.1

Table 3.1 Configuration of the motor

Voltage

12 VDC

Output Power

1.1 W

Rated Speed

58 RPM

Rated Torque

25.4 N.cm

Rated Current

0.41 A

Gear Ratio

1.6

Length

37 mm

Weight

160 g

3.6 Relay

5 volts relays for outputs 12 volts relays for some input sensors. The relays are used as switch in which they separate the required voltage for the devices used and the control signal voltage of the micro-controller. When the microcontroller obtains signals from the LDR which we will discuss in the chapter 3.7 the micro controller will send a signal to the relay to off the supply to the valve to avoid fluid over flow in the "Automatic Cold Drink Vending machine" the basic schematic design of the relay switch is shown in the figure 3.3 for understanding.

Figure 3.3 basic schematic of the Relay switch

For our relay we use a 2N3904 Transistor with a resistor of 1K which is connected to the base of the transistor. And a diode 1N4148 connected to the collector of the transistor.

As the mathematical modeling of the transistor is given as,

Hence

Now,

Note: β is alway specified in the datasheet

Here βis 140 and hence

3.7 LDR

The Light Dependent Resister is a darkness controlled light switch works on the principle of the effect of light on the LDR (Light Dependent Resistor). LDR is an electronic component that changes the value of its resistance according to the intensity of light. It is used to trap the intensity of light for the operation. Here, the resistance of the LDR depends inversely upon the intensity of the light. As the intensity of light increases the resistance of the LDR decreases and vice versa. The principle is utilized to operate the relay, which further operate electrical & electronic appliances.

As the electronic components are very sensitive the performance of the product is also more appropriate and can work in the high accuracy. During the project, PCB fabrication is also important task.

For the working of the circuit we uses the general Purpose 2N3904 n-p-n transistors. The overall operation is brought about by the use of following components

i Light dependent resistance ( LDR ) [photo conductive cell ]

ii General Purpose 2N3904 n-p-n -type transistor

iii Relay switch

There are two modes of operation:

I. In darkness (Low intensity):

In this condition, the resistance of the LDR is high. Hence, the base – emitter voltage of transistor T1 is lower than the collector-base voltage of T1. Since the voltage across the emitter and base is lower than the threshold voltage, the transistor T1 does not conduct. At the same time, the emitter base voltage obtained by transistor T2 is greater than the threshold voltage. Hence, transistor T2 conducts and completes the circuit through the relay switch thus activating the relay and hence the appliance.

II. At brightness (high intensity):

The resistance across the LDR is low. Hence the emitter- base voltage of transistor T1 is greater than the collector-base voltage of T1. Since the voltage across the collector and base of T1 is greater than the threshold voltage of the transistor, the transistor easily conducts. At the same time, voltage obtained by transistor T2 is not enough to provide the base biasing. As a result the current flows through the transistor T1 only but does not flows through T2. Hence the relay is not activated. The basic schematic design of the LDR is shown below in figure 3.4.

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Figure 3.4 schematic diagram of the LDR

3.8 Opto slotted switch

The reflective optical switches combines an infrared emitting diode (IRED) with an NPN phototransistor or photo Darlington in a one piece, sealed, IR transmitting plastic case. Sealed construction improves resistance to moisture and debris. In its most basic form, a reflective optical switch (retro) consists of a housing which holds both a light source and a detector. Light from the lamp of LED radiates outward and is reflected back should an object be placed in front of the switch.

The reflected light is sensed by the photo detector whose output signal changes accordingly. There are a number of different types of reflective sensors. Designs vary depending upon the application. All have certain characteristics in common. How well they detect an object depends on following characteristics and the schematic figure of the Opto slotted switch is shown in figure 3.5

1. Amount of light emitted by the light source.

2. Sensitivity of the photo detector.

3. Distance between the switch and the object being sensed.

4. The light reflecting properties of the object.

5. Ambient lighting conditions.

6. The perpendicularity of the reflective surface to the switch.

Figure 3.5 schematic figure of the Opto slotted switch

3.9 Key pad

Key pad is the main input source for the consumer in the "Automatic Cold Drink Vending machine" project where the consumer uses the key pad to key in the data in to the machine to initialize his/ her transaction. The key pad we use here is a 3 × 4 matrix numerical key pad.

The operation of the keypad is there are two methods of operation: continuous polling, where the Micro Converter spends most or all of its time checking the keypad for a key press; and interrupt driven, where the Micro Converter is free to perform whatever other tasks are required and checks the keypad only when a key is pressed.

In this project we use a continuous poling operation where In this mode of operation, the Micro Converter continuously polls the keypad for a key press. This operation is used where the Micro Converter has completed a task and is now waiting for input before proceeding. In this mode, the keypad is connected to one port of the Micro Converter, Port 2 in this example. Figure 3 shows the connectivity. The output from the Micro Converter, following a key press, is viewed using HyperTerminal running on a PC. The Micro Converter is connected to the PC via the COM1 port. This is the reason for showing the RS-232 connection. The image of the 3 by 4 numerical key pad is shown in figure 3.6.

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Figure 3.6 3 by 4 Numerical figure key pad

3.10 Status LED

The status LED is the indicator output of the "Automatic Cold Drink Vending machine" where it emits light to the consumer notifying the status and condition of the process of the vending machine so that the consumer is well informed about the condition his/her transaction.

3.11 LCD

The LCD is the detail display for the consumer which serves as the main notification device in the output section of this project. The 2x16 LCD A Module provides versatile display functions. Through its simple connections, it can be controlled by Innovati’s BASIC Commander for a wide range of LCD applications.

In this module, two display lines, each with 16 characters on each line can be displayed. By using the cursor control command, the position of the character to be displayed on the screen can be arbitrarily changed. In this module, the backlight function can be used to change the backlight to allow the message to be read easily. In addition, it can be configured to display user defined characters to display any specially required characters. Please use "LCD2x16A" as the module object name in program.

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Figure 3.7 LCD (2X16)

3.12 Buzzer

The buzzer is the final output module of the system where it notifies the consumer by sound medium to notify the status of the transaction in this project the buzzer will buzz at the start of the start of the transaction and the end of the transaction.

3.13 Circuit Design

3.14 Solid work Design