Analysis of Fingerprint Access Control in Intelligent Buildings

Intelligent buildings are the inevitable result of the information age. They are the result of close integration of sensor technology, computer technology, communication technology, control technology and building technology. Through various information technologies, they effectively implement resources for the entire building. Management will rationally schedule, monitor, and manage resources throughout the building, thereby increasing the efficiency of the management of the entire building. It can centralize monitoring, control and management of distributed and independent resources using the same environment and the same software interface. Intelligent building systems generally include: office automation systems, fire automation systems, security systems, and communications systems.

The access control system is part of the security system. The safe and reliable system is the key to the entire building. Currently in many current computer systems, the user's identity authentication mostly uses the "user ID + password" method. In fact, this method implies that security issues such as passwords are easily forgotten, passable, and easy to be stolen by others. Because biometrics are unique to everyone on the human body, using these biometrics as authentication methods is more secure. In view of the above issues, this article discusses in depth the fingerprint authentication-based access control system.

1 fingerprint authentication principle
We know that fingerprints are unique, and its uniqueness actually means that each person's fingerprint is not the same. This uniqueness is also the principle of using fingerprints to distinguish different individuals.

Based on the analysis and classification of a large number of fingerprint images, we can roughly classify fingerprints into six types. (a) arch, (b) rightloo, (c) tentedarch, (d) 1eftloo, (e) whorl, (f) Twinloo.

For the above six types, fingerprint matching is also divided into pre-classification and precise classification. The so-called pre-classification is to divide the input fingerprint image into one of the above six types. After the pre-classification is completed, the precise classification is performed. The precise classification uses the comparison between the detailed information of the fingerprint image to accurately obtain the similarity of the fingerprint image. .

The fingerprint recognition technology first reads the fingerprint image through the image capturing device, then uses the computer recognition software to extract the fingerprint feature data, and finally obtains the recognition result through the matching recognition algorithm. The basic block diagram is shown in Figure 1.

1.2 fingerprint authentication algorithm

For the whole process of fingerprint authentication, the extraction and matching of fingerprint features is the key to achieving the entire access control system. As an access control system, its main task is to ensure the security of the entire intelligent building, that is, through different users to be identified, it must be able to accurately distinguish which authorized users can enter and which are illegal users, and block the The user enters the room to achieve the management of the building staff. Thus it can be seen that the correctness of fingerprint identification is a crucial step in building safety management. Through the review and analysis of a large number of materials, we use the following four steps to identify different fingerprint images through experiments. It is proved that this method has better recognition effect:

1) Use the fingerprint collector to obtain the user's fingerprint: Install a fingerprint collector at the entrance of the building, collect the user's fingerprint through the tool, and input it into the computer.

2) Fingerprint image preprocessing: The image obtained by the fingerprint collector will inevitably be doped with some noise. These noise points will affect the recognition of the next step. Here, the preprocessing process is to convert the acquired image into the most suitable one. Identify the image. The main processing methods include: image enhancement, image denoising, image refinement, binarization and so on.

3) Image feature extraction: After the image pre-processing is completed, the fingerprint image to be identified is to extract features. Feature is the key to distinguish different fingerprint images. Fingerprint recognition and matching is feature extraction. A good feature extraction method largely determines the accuracy of late identification. Here we use the coordinates and direction fields of the fingerprint image feature points as the final feature vector, and use this feature to identify and distinguish different users, as shown in FIG. 2 .

4) Pattern recognition and matching of images: Finally, according to the extracted features, different fingerprint images are matched and identified. In order to enhance the robustness of fingerprint matching, feature vectors of feature points are converted into polar paths, polar angles, and directional fields in polar coordinates. The use of a variable bounding box method corrects for nonlinear distortions and positional differences in the process of image acquisition.

The purpose of fingerprint authentication is to allow who can enter the system, who can not enter the building, and grant different permissions to different users. The basic idea is to obtain the fingerprint of the user to be logged in, and match the fingerprint with the fingerprints of all users pre-registered in the data. If the matching is successful, the user is a legal user, and authorization is performed according to the permission definition in the data; otherwise, the authorization is illegal. user.

2 Fingerprint authentication-based access control system

The access control system is usually composed of a controller, a card reader, an electronically controlled lock, a door lock, a door opening button, an extension module, a system server (computer), a communication converter, an access control management software, a communication manager, and a management host. Based on this, the design of the access control system based on fingerprint authentication is carried out. The design of the entire system can be divided into the physical network structure module and the fingerprint identification authentication module of the access control system. The physical network structure module includes the physical structure of the access control system and the installation of the instrument and equipment, so as to construct the physical structure of the entire access control system. The fingerprint authentication module is mainly the design and implementation of software and the establishment of authorized user fingerprint data, and is achieved through the software. For user fingerprint authentication.

The network structure diagram of the entire access control system is shown in Figure 3: It mainly includes: servers, switches, access control devices and archiving equipment. The server also includes a database server and a web server. The database server stores fingerprint information of all legitimate users, obtains the user's fingerprint information through the access control device, and transmits the user's fingerprint through the network during the database service period of the intelligent building. The feature is matched with the fingerprint feature of the legal user stored in the database server. If the matching is successful, the access control system opens and the user is allowed to enter. Otherwise, the user will be rejected. In addition to the basic intercom call function, the fingerprint-type access control unit incorporates a fingerprint unlocking function and introduces unlocking modes such as normal unlocking, emergency unlocking, and coercive unlocking, which improves the security of the access control system and facilitates use. In addition, each fingerprint-based access control unit is an information node on the network. The opening, closing, and failure information of each unit is timely transmitted to the access controller, which provides a favorable guarantee for the security of the smart community. The terminal management machine (PC) has a large-capacity hard disk, which can save and manage the information of the access controller for a long time.

The whole fingerprint authentication algorithm system adopts a hierarchical module design and is divided into three layers. The bottom layer includes a data table module, a classifier module and a template fingerprint database. The middle layer is an interface layer and includes a feature extraction interface, a feature matching interface, and a fingerprint library operation interface. The upper layer is the application layer and includes fingerprint registration, fingerprint verification, fingerprint authentication and fingerprint library management. The hierarchical relationship of each module is shown in Figure 4.

Figure 4 fingerprint authentication system module

The module first extracts the fingerprint image of the authorized user data, extracts the coordinate and direction field of the fingerprint, establishes a fingerprint image feature database, and registers in the database. In the access control system, the login user's fingerprint feature is acquired through the collection device and matched with the data in the database to determine whether to admit the user.

3 conclusions

In the process of intelligentizing buildings, the access control system as a security system is the key to ensure building safety management. In view of the security problems such as the easy-forgotten, transferable, and easy to steal and misappropriate passwords existing in traditional access control systems, this paper proposes an access control system based on fingerprint identification. As a representative biological feature, fingerprints can distinguish different Users have higher security than other technologies. This paper deeply studies the related technologies of fingerprint identification, and applies it to the access control system of intelligent buildings, which has high applicability and application value.

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