Radio Frequency Identification for Library

Background

CE 1.1) RFID (Radio frequencyIdentification) technology is one of the most evolved technique in our contemporary time with huge potential ranging from applications as simple as implementation a gate security system to as complex and exigent as automatic money transfer system. The project for designing and implementing a RFID system for libraries employs the broader use of radio frequency technique along with PLCs in algorithm for security control, access control and tracking system of the library.

CE 1.2) RFID technique is an upgrade from bar-code technique which has been previously employed for realizing the same task. The bar-code consist of images of lines affixed with varying spacing against which there is information stored for the particular product to which the specific barcode has been assigned. Unlike RFID, bar-code technique uses light transmission for communication between the ‘reader’ and the bar-code. The reader in this case gather the information from the barcode and converts it into digital data for practical use.

CE 1.3) RFID technique is much more elaborate, sophisticated, and accurate as it provides greater flexibility in workings of a tracking and control system as compared to a barcode system. Barcode is an in line of sight technology means it only works in the vicinity system which is in line of sight to the ‘reader’ while RFID in this case provides much greater flexibility as it isn’t in line of sight technology but works in the an area which a specific radio frequency range which can range from (kHz to 500KHz), (800MHz to 950Mhz) and (2.4GHz to 2.5GHz). Greater the radio frequency, greater is the range of the system and vice versa. It has high range and is less affected by atmospheric conditions as compared to barcodes. RFID also enables multiple readings at a time which in case of barcodes cannot be realized.

My final year project on designing a security, access, counting and tracking system for my university library employs the basic concept of Radio frequency identification in an assembly of an antenna, transceiver, a transponder and a PLC system working in such a way that one begets the working of the other. In this case, antenna is used for radio frequency transmission in its vicinity as per its design. The antenna activates the transponder which after activation sends the data back to the antenna which then takes it to the PLC for data acquisition and for decision making. 

CE 1.4) The basic implementation of the project is such that initially at CESCO the analysis of various aspects of library was carried out and various parameters were found out which may affect the implementation of algorithm of the system. This was done in the early stages of the projects which the help of senior staff at library. A basic catalog of books, shelves, categories and the logical order of the premises was considered before any work on the algorithm and design. Subsequently based on the knowledge at hand, I allotted for antennas (which were transceiver) for each shelf on the library for counting and tracking mechanism with radio frequency range of 920MHz to 928MHz. The information gathered by the antennas as per the switching circuit design technique which I will explain later in this thesis would be transmitted to computer for data acquisition and decision making.

The main features of the project can be categorized as:

• ·         Design of patch antenna with specific radio frequency and range.
• ·         Design of switching circuitry for selection and data acquisition on PLC.
• ·         Implementation of a computer assembly for the acquisition of data and decision making.

·     The main focus in this project has been the design and implementation of switching circuit and the patch antenna. To design an antenna of specific frequency which high precision and range was one of the biggest challenges of this project along with switching circuitry which had to play a major role in gathering data and decision making on PLC. 

CE 1.5) The working on the project turned out to be smooth and time managed which cordial and knowledgeable collaboration with my supervisor and the respected faculty at CESCO. I held regular meetings and insightful discussions with the supervisor whose ideas and lectures helped me much in grasping the theoretical concepts of the project. I had late night working with a lot of friends and colleagues without whose input and guidance, realizing this project in the specified amount of time could not have been possible.

A structural flow chart of the working on the project is given as below:

Personal Engineering Activity

     

CE 1.6) The implementation of RFID system can be divided into five steps for smooth working and better knowledge comprehension. I carried out the work in five steps starting from the design of patch antenna, reader, switch circuitry for the selection of antennas on the shelf, computer environment for data acquisition and tag designs for various books and shelves in library.

Now I will explain in detail the technical details of all five stages of the project.

CE 1.7) Patch Antenna was designed for the radio frequency of 920MHz to 928Mhz and four patch antennas were allocated for each shelf in the library to get the tag information i.e., ID code and locational information regarding the particular item.

In the design of antenna two techniques were employed. The gist of 1^st techniques was to add a matching network between the part of antenna and a 50Ω line in order to do the matching. A basic diagram of such an arrangement is given as below:

 

Fig. 1 Matching of Antenna and 50 Ω line.

The second technique of the design of patch antenna is such that the 50Ω line is inserted into the antenna part and in this was when the insertion position gets correct, the loss in power due to inductive component will be the lowest. A basic diagram of the implementation of 2^nd method is given as below:

Fig. 2 adding matching network with antenna parts

Initially the size of the antenna was selected to be 90mm high and 90mm wide and simulations were done in order to standardize the size of the antenna. 90mm was chosen as a reference and it was found out that with a decrease in the size of the antenna, the resonant frequency was increased. So by varying the size of the antenna and checking the corresponding radio frequency at zero impedance, if the imaginary part of the frequency turned out to be equal to 920MHz to 925MHz then our design was correct. In this way the antenna was designed.

After the design of antenna, the second part was to improve the return value of antenna. For doing that, we designed a matching network. In this case, the impedance of the matching network was calculated and it was found out to be 160 ohm.

Third thing to consider in antenna design was the design of 50 ohm line.

CE 1.8) Switching circuit as discussed above is used for the selection of antenna of the shelves and transmit data from the shelf onto the computer via the antenna. The switching circuit was built using an inductor, capacitor and a PIN code. The switching circuit had one input ports and four output ports and it was controlled by voltage impulses. 

The switching circuit works as a bridge between the transmitter and the reader. The power loss which arise due to inductive component here is of much importance here and the motivation is to decrease it as much as we can. It is found out that if the value of the inductor is chosen to be large enough than inductive loss can be reduced. A simple switching circuitry is given as below:

Figure 3 Switching Circuitry

CE 1.8) Reader design was next in the implementation of RFID system. Reader here is supposed to be a static switch which is in inactive state when it doesn’t receive any data from the computer but it turns on in an event of receiving data from the computer. Receiver is one the receiving end of the antenna and the data as selected by the switching circuitry is transmitted from the antenna is received here.

Computer Interface was the next stage in the implementation of the project and a PLC technique was designed for the acquisition of data from the antenna for decision making. An algorithm was designed so that counting of books, the positioning and tracking was done through RFID. It worked so that finding the place of the book on a shelf in library was made easy and time saving.

Tag making for books and shelves was the nest stage for data had be collected based on the tags of the books and shelves.

Summary

CE 1.9) This project has been a great learning experience for me as working on it instigated and stimulated the depths of my mental capability, personal development and intelligence with a unique and intriguing challenge that it posed. It helped me in interacting with people, seeking help and working in a team. All in all this project is of marquee importance in various fields which require the need of a sophisticated technology, security, identification, control etc.