Design and Development of RFID Book Counting Intelligent Robot

- Jul 20, 2018-

As a kind of radio frequency technology, RFID can read and write data by using radio signals for identifying specific targets without the need of mechanical and optical contact, and has many advantages such as fast, safe, and reusable. Favor. By 2016, RFID technology has been used in China's libraries for a full decade. From the sporadic fire to the widespread use in the library industry today, it can be said that the application of RFID technology in libraries has promoted the library service model. The development and changes in many aspects, such as management platforms and service content, have not only changed the traditional circulation methods, but also expanded the space and time of services. For librarians, the use of RFID technology not only reduces the difficulty of the work, but also improves the effectiveness of the service. The combination of library and RIFD technology has undoubtedly brought great convenience to readers and librarians. In the future, RFID technology will continue to play an important role in the development of smart libraries.

I. Current status and limitations of library book management

As a basic work of the library, book inventory is very important for librarians to understand the paper resources of the library. By timely checking the books in the shelves, you can accurately grasp the number and location of the books, so that the librarians can keep abreast of the books in the shelves and facilitate the readers' inquiries. At present, the methods of counting books mainly include manual counting, barcode scanning and counting, and RFID device inventory.

Taking the Nanjing Library as an example, the books on the open shelves are distributed on two floors, and about 900,000 books are distributed in circulation. The total circulation of the books is more than 3 million. Faced with huge liquidity, how to ensure the accuracy of circulation resources and improve the efficiency of the circulation of books, these problems are all achieved by book inventory work. As an important part of the reader service, from the early manual inventory to the use of RFID handheld devices, the librarians and readers can accurately understand the situation of paper resources and improve the quality of library reader service.

At this stage, the use of RFID technology to count books is increasingly used by libraries, because RFID technology inventory books not only complete the workload that may take several times before, but also increase the accuracy of the book inventory, The preference of most librarians.

 Taking the Chinese Library's Chinese loan room as an example, RFID book inventory work is divided into two methods: end-of-term inventory and cycle inventory. The end of the inventory is carried out in the closed room, the data is delayed but the accuracy is high; the cycle count is carried out at the open time through the fixed period, and the timeliness of the data is high, but the interval of the cycle determines the intensity of the work. Since the current information on books in the books can be known in time, the cycle counting method is also widely used in libraries. By compressing the time interval between data collection, the reader is able to obtain the exact location of the book while borrowing, while at the same time allowing the librarian to understand the complete information of the book. Some libraries use 3D rendering to allow readers to visually see the location of the book on the web page, greatly facilitating the reader's access to paper resources.

 However, since the main body of book inventory work is still a librarian, RFID is only an auxiliary technical means to achieve inventory work, so we believe that this still does not leave the traditional way of manual inventory. In order to obtain the accuracy of the information on the shelves, it is often necessary to increase the frequency of inventory. Librarians need to spend a lot of time going back and forth between the bookshelves, which invisibly increases their basic labor time, thus reducing the The time the reader is directly serving.

 Second, the combination of RFID technology and book counting intelligent robots

A smart library is the mainstream of the development of the library business. One of the important forms of expression of a smart library is the degree of librarians' knowledge of the service. As a bridge between readers and books, librarians can combine RFID technology with intelligent robot technology to design a book inventory intelligent robot with RFID as the core technology, which is characterized by no influence on time and space. In the open environment, the inventory can be automatically carried out on the target bookshelf through the inventory instructions issued by the librarian. Will greatly change the status quo of book inventory work. By replacing the traditional manual inventory work with intelligent robots, we can break through the single mode of library service methods, promote the transformation of library service methods, and create diversified service forms.

 Third, RFID book inventory intelligent robot design requirements and implementation conditions

 Design requirements: The scope of robot application should include both open frame and closed frame. The case of book inventory under open frame mode should be more complicated than that of closed frame. This paper discusses the automatic calculation of book inventory under the open frame mode. Design requirements include the following:

Self-test function of the robot. Before starting a series of work, you must complete the self-test of the equipment to ensure that the various components can operate normally, and whether the battery power supply can support the equipment to complete this order.

 Get the actual situation topology of the current map bookshelf. The shelf information of the current bookshelf can be planned in the system, which can make the device have an objective judgment and analysis on the current shelf information before running.

 The positioning of the robot and the path of the trajectory. Firstly, it is necessary to construct the map of the entire open environment effectively, and plan a reasonable travel route, and automatically return to the preset line when the device deviates from the position. If you encounter obstacles on the route you are on, you should wait a little and then make a new route plan based on the actual situation.

 RFID technology is used to count the books in the shelf, and the robot arm moves in the front, back, left, and right directions of the three axes when the book is counted. The robot arm of the book should have a 3-axis movement function to ensure that there is no omission in the book inventory process. After the completion of the inventory task, a summary of the situation is formed. After the end of the inventory operation, a summary of the process of the inventory is required and presented to the librarian.

 Running logic: The logic of the robot running system is shown in Figure 1. After the librarian issues the order for the book inventory, the system automatically starts to enter the working mode. The robot first determines whether the power system can complete the work and whether the equipment is available. Failure, if the system remains normal, the device will inventory the bookshelf books according to the planned route. If there are readers or other obstacles, the device will automatically stop waiting. If there is a deviation from the line, according to the signal source in the preset line, the nearest source is re-entered into the planning line. When the book is booked, according to the image recognition system, first determine whether there is a bookshelf tag. If the shelf label is found, The bookshelf is counted. After the completion of the complete inventory action, the inventory work will be presented to the librarian and returned to the charging position for standby.

System composition: For example, the whole system consists of five subsystems: power supply system, image sensing system, navigation and positioning system, mechanical drive system and RFID inventory system.

The equipment design runs independently between the bookshelves for book inventory, and the power supply system is mainly composed of rechargeable batteries. The image sensing system includes visual image analysis, infrared ranging, for observing whether the device encounters an obstacle during travel, whether the device is operating in the track, and observing the bookshelf number to determine its actual position. The navigation and positioning system consists of a wireless receiver, a map construction system, and an offset homing system. During the system initialization phase, the entire indoor environment needs to be initialized and mapped, and the traveling route is planned. When the track is off track, the system needs to pass the wireless receiver. Find the nearest initialization point location and re-enter the track. The mechanical drive system consists of a motor motor system, a mechanical arm system, etc. The motor motor system is used for the travel and stop of the device. After the mechanical arm system is used to reach the inventory area, the device moves through the mechanical arm to drive the RFID device to inventory the book. The RFID inventory system is used to count, enter, summarize, etc. of the book inventory, and present the complete information, so that the librarian can visually see the current book in the shelf.

Fourth, RFID book inventory intelligent robot structure design and key technologies

Structural design: The two-dimensional structure design of the RFID book inventory robot is shown in Figure 3. The robot consists of two parts: hardware and software. The hardware includes DC power supply for lithium battery pack, motor-driven brake device, arm sliding device, distance and image. Inductive equipment host hardware and display, RFID tag identification and other equipment. The software includes control programs for each hardware, enabling the device to run in the planned route in a programmed manner. If it encounters deviations from tracks and obstacles, it can judge the book inventory again.

The two-dimensional structure design of the RFID book inventory robot is composed of hardware and software. The hardware includes DC power supply for lithium battery pack, motor-driven brake device, mechanical arm sliding device, distance and image sensing device host hardware and display. Screen, RFID tag identification and other equipment. The software includes control programs for each hardware, enabling the device to run in the planned route in a programmed manner. If it encounters deviations from tracks and obstacles, it can judge the book inventory again.

Key technologies: Traditional ways to build maps are metrics and topologies. The metric map is further divided into a feature map and a grid map. The feature map refers to the robot perceptually sensing the surrounding environment through the sensor, thereby achieving the effect of precise positioning, and is highly complex due to high requirements for equipment observation information and the like. Environmental map construction. The raster map is that the entire environment map is divided into small map blocks by using a grid method. Each block is distinguished by 0 and 1 to identify whether it is an obstacle or a movable area. This method is simple to create and easy to maintain, and is more common. Used in less complex environments. Topological maps use blocks to divide key areas in the environment, while edges between areas represent relationship connections. For example, in the library open environment, the bookshelf area and the viewing area can be used as two different areas. It is easy to divide each area and it is easy to expand, but it is difficult to achieve precise positioning within the area.

The main working area of the robot is in the library shelf area. The location of the area is relatively fixed, and the viewing area is clearly divided. Therefore, this paper uses the topology map + track ribbon identification to plan the travel route of the robot, using the ribbon logo. The way to increase the accuracy of the robot's positioning in the travel area. Robot travel navigation

We divide the whole area into two parts, one is the bookshelf area, and the other plan is the reading area. The robot finds the moving track mark according to the ground in advance in the bookshelf area through the visual system at the bottom, according to the track color mark. The route is used to carry out the inventory work, and the preset track mark is made in the shelf label area, and the robot travels to this area to stop running and start counting the shelf book. If the robot is currently in the viewing area, re-enter the preset track area by searching for the lost signal source and proceed to the last inventory work.

 The robot arm is divided into three directions: X, Y, and Z axes. The X axis represents the width of the bookshelf, the Y axis represents the height of the bookshelf, and the Z axis represents the depth of the book or book shelf label. When the robot travels along the track ribbon mark to the designated shelf, it is necessary to first obtain image information through the vision system, determine the number of bookshelf tags, and move the RFID disk point along the Y axis of the arm to the shelf label position that needs to be counted. Scanning is confirmed, and then according to the image identification information, the position of the book spine of the layer is obtained, the depth of the Z-axis of the robot arm is determined, and the book is scanned.

13.56MHz RFID reader antenna matching design method

In general, the number of layers of the bookshelf and the width of each shelf are fixed. The distance between the arm and the height can be determined by the preset width and height values. It should be noted that the position of the books may be inconsistent, so the image is passed. It is very important to obtain the position of the spine and obtain the depth of the book to be counted by distance sensing. Try to keep the position of the RFID counting device close to the spine, which can effectively avoid the inventory inaccuracy caused by signal omission during the counting process. The identification of the book spine can be obtained by the index number below the spine. The call number is attached to the lower part of the book's spine. This obvious feature provides convenience for image processing. After the algorithm such as gradation and binarization, the information such as the position of the spine can be clearly identified by the call number, which provides a good basis for distance perception.

The book inventory system reads the data of the books and bookshelves by the RFID reader, and stores the data in the database. The front end combines the business system data to display the shelf and book information. The system structure is shown in Figure 6. The tag identification technology is now mature, and the RFID tags of books and bookshelves are identified by RFID readers, and bar code information of the book or bookshelf is read.

The inventory system design is divided into four aspects: display layer, application layer, database and basic platform. The front-end RFID reader obtains the barcode number, stores the data in the rack database, and forms the complete map bookshelf information. The application layer design is divided into four functional modules: collection, sorting, updating, and culling, providing librarians with a complete book inventory workflow to meet a variety of business needs. By obtaining the complete information of the book in association with the business database, the complete map book position information is finally presented on the front-end display platform. In the front-end display platform, through the software such as Unity3D combined with the map bookshelf information, a complete 3D scene model can be displayed, which is convenient for readers and librarians to intuitively search for books.