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1. INTRODUCTION
Implementing Radio frequency identification (RFID) within the four walls of a manufacturing Plant requires extensive analysis and experimentation. The term Automatic Data Capture (ADC), Also known as Automatic Identification and Data Capture (AIDC), refers to the technologies that Provide direct entry of data into a computer or other microprocessor controlled system without using a keyboard. Many of these technologies require no human involvement in the data capture and entry process RFID tags coupled with readers and information systems architecture can increase visibility of Operations by associating unique product identification with its current location, and by Synchronizing the physical flow of components/products and the related information flow Without human intervention. In addition to being an enabler of visibility, RFID technology has found uses in a variety of other manufacturing related applications in production automation and inventory management.
Despite RFID’s success, confusion still remains as to where it can help in manufacturing. Questions remain as to what aspects should be considered when selecting applications, which manufacturing wastage RFID may specifically address, and how these wastages can be identified
RFID is an electronic method of exchanging data over radio frequency waves. It is one of the methods of Automatic Identification and Data Capture System (AIDC)
Radio frequency identification (RFID) is a wireless form of automated identification technology that allows for non-contact reading of data which makes it effective, for manufacturing and other hostile environments where bar code labels may not perform well.
Radio Frequency Identification Devices ("RFID" tags) consist of a computer chip attached to a loop of wire and encased in a plastic film. When they pass through a magnetic field, an electrical current is generated in the wire that powers the chip to transmit its identity and potentially other information to an antenna.
RFID has opened up immense possibilities the world over, particularly, in Supply chain
Management and retail. In India, the technology has been taken a step further. The Kopordem farm at Valpoi in Sattari Taluk in North Goa has become the first farm in the country to use RFID microchips. These chips have been injected into 500 cows; the objective is to provide unique identity to each animal. These chips would also help in inventory control and integration of health records and database. RFID is catching attention of businesses the world over
The seven wastes versus RFID.
Lean manufacturing is ‘a philosophy of production that emphasizes the minimization of the amount of resources (including time) used in the various activities of the enterprise’. Lean manufacturing involves identifying and eliminating non value adding activities and focuses on the start-to-end value streams rather than the idea of optimizing individual departments in isolation. Waste is a term frequently associated with lean manufacturing. In this section we look into the seven wastes of manufacturing systems and consider how they can be reduced using RFID to move towards a lean organization.
The following wastes are given:
1. Overproduction, which discourages a smooth flow and leads to excessive lead and storage times.
2. Waiting, which occurs when time is being used ineffectively.
3. Transport, a non-value adding operation which involves goods being moved around.
4. Inappropriate processing, which occurs when systems or procedures more complex than necessary are used, leading to excessive transport and poor quality.
5. Unnecessary inventory is unused capital, leading to storage costs, or possible quality deterioration of goods if the time of storage is critical to its health.
6. Unnecessary motion refers to the ergonomics of production when workers need to move in unnatural positions repetitively, possibly leading to tired workers and compromises on quality.
7. Defects are costs directly attributed to wastage of produced material that could potentially bring revenue.
2. CONCEPTS OF RFID
The easiest way to understand rfid is to think of signal mirrors. for centuries we have known how to communicate messages by flashing sun reflection in the direction of reciepient.The flashes are Sequenced to represent a code known by recipient. THE flashes are sequenced to represent a code known by flashing sun's reflection in the direction of the recepient.THE flashes are Sequenced to represent to represent a code known by the recipient, for example mores code, the communicates intelligence without the necessity of an infrastructure that establishes physical contact (for example, a telephone line) so messages can be sent through air simply by reflecting radiated sunlight as our communication system, we reflect radio waves.
The basic theory underlying RFID technology has been understood since the 1930s.Early on it was discovered that the introduction of a conductive material into electric or magnetic field could alter the field's charachteristics.that occurs because the conductive material both absorbs and reflects the energy in the field. if the field is a radio frequency or RF the conductive material imparting a reflection of the source field radiation.
RFID technology takes advantage of that characteristics by manipulating the sequence and rate at which that reflection occurs called modulation. RFID tags are designed to deliberately reflects the source rf in sequences that are interpreted as information in the form of digital data.
Radio Waves
Light x rays and radio waves are all electromagnetic waves the only difference between them it the frequency at between them is positive and negative polarity./the number of waves that occurs in one second is known as frequency and in hertz. one hertz is one wave oscillation per second.
3. PRINCIPLES OF RFID TECHNOLOGY
The most basic radio frequency identification solution is made up of three main hardware components. These components are the RFID tag, the RFID reader, and the antenna. This is, of course, an over simplification of what it takes to apply today’s RFID technology to a real world problem, but these are the fundamental building blocks. Understanding the fundamentals of RFID is the key that allows practitioners to be successful in their application of the technology. Even though this article does not discuss the software required to interpret and make use of the RFID data, its role in a complete RFID solution is vital.
The components of the basic RFID tag are an integrated circuit (IC), an antenna, and the substrate that holds it all together. The IC is responsible for controlling the tag; much like a CPU controls a desktop computer. The IC controls what is broadcast from the tag, processes commands received from the reader via the antenna, and manages any peripherals such as temperature and pressure sensors. The antenna plays multiple roles in most RFID tags. It is responsible for receiving and transmitting data from and to the reader, and, in the case of passive type RFID tags, they collect the energy required to power the tag. Passive tags power themselves off of the energy they collect from high gain antennas that are connected to the RFID reader; therefore, they must be in close proximity to the RFID reader’s antenna in order to collect enough energy to function.
RFID tags with onboard batteries are known as active tags. Unlike passive tags, they transmit their data even when they are not in close proximity to an RFID reader. In most cases, active tags can be read at a longer distance than passive tags. There is a hybrid tag known as the semi-active tag. It has an onboard battery just like the active tag, but it will only transmit when it is in close proximity to the reader.
RFID tags may transmit many different pieces of data, but the most fundamental piece of data is the tag’s unique identifier. The unique identifier is, in most cases, associated with a real world asset that is to be tracked. The unique identifier is used as the key that identifies information about an asset in a database in most applications. Tags may also transmit state information or telemetry such as temperature or humidity if they have the sensors to collect this type of information. Most passive tags do not have peripheral functionality due to the power limitations of not having an onboard battery.
The RFID reader is sometimes referred to as the interrogator. The reader receives all of the data that the tags are transmitting. The data is then passed on to software that makes use of the data. The tags that are in close enough proximity to a reader are referred to as the reader’s “tag population.” As a reader’s tag population grows, the density of tags around the reader also grows, and the reader may require more time to read all of the tags in its vicinity. This is due to the fact that if all the tags transmit at the same time, the reader will not be able to separate their data into discreet transmissions, so it is important that the tags do not transmit all at once.
Passive tag readers select subsets of the population to query over time until beacons from all of the tags in the population have been received. Most active tag readers do not control the sampling of the tag population like passive readers do. Active tags beacon at a pseudorandom interval to avoid transmission collision with other tags. Anti-collision algorithms such as the ALOHA algorithm determine when the tag will beacon. The ALOHA algorithm assigns transmission time slots to each tag. The name ALOHA is not an acronym, but was given its name because it was developed at the University of Hawaii. The ALOHA algorithm is a common anti-collision algorithm that is used by many RF applications, not only RFID. Over time, the randomization of the tag transmissions will ensure that the transmissions from all the tags are eventually received. There exists a threshold where the tag density is so great that it cannot be guaranteed that all the tags will be sampled in a timely manner. The tag density maximum is different for each RFID tag and reader manufacturer. Some manufacturers even allow the anti-collision algorithm to be changed based on the needs of the solution.
The importance of the antenna that is connected to the reader cannot be underestimated. In a passive RFID solution, the antenna must be sensitive enough to receive the RFID tag transmissions and it must also be powerful enough to power the tags. Passive tag reader antennas may be deployed in many different configurations depending on the application. A portal configuration is the most common type. Portals place an antenna on each side of the tag’s path (i.e., at a loading dock door or on an assembly line). Sometimes, a portal configuration may also affix antennas on the top and bottom of the pathway to completely surround the tag’s path, thus increasing the chances of reading the tag as it passes through the portal.