Automated House Security and Access
(AI House)

D. Bañez, M. Caparas, M.D. Cu, H.M. de Guia, E. del Castillo, J. Tanqueco, P. Woo

T. Calasanz and C. Oppus

 

Abstract. With the development of technology, more sophisticated security and access systems are made available in the market. However, they are accessible to a limited sector of the society due to their high cost. Thus, there is a need to build a system that is less expensive, but comparable to commercially available security and access systems.

This project develops an alternative security and access system that makes use of economical small-scale circuits interfaced to a computer. It features an automatic presence detector implemented using Piezotite Ultrasonic Sensors MA Series, a dual security level door access through speech-recognition and numeric password entry, and an automated power-saving intercom system. All these are controlled through the main console written using Turbo C++ and Matlab. The overall system is designed to time stamp detections, handle different access scenarios of the house members, visitors and intruders, and includes a valid access database to create user-event associations, manual control interface, and is integrated via the enhanced parallel port of the personal computer.

The security and access system is designed and developed for the AI House Project, therefore, the module also provides direct link to the central house computer for event updates, warning messages and for control from the main computer of the AI house.

  1. INTRODUCTION

    2. Smart Houses are homes that make use of technology to control automatically household devices and systems. They also communicate information about their status, through local and remote mechanisms, and provide security. AIHouse is a Smart House prototype. Its security and access system, composed of presence detection, speech recognition, pin code identification, automatic door lock operation and events log file system, is developed for AIHouse.

  2. STRUCTURE AND COMPONENTS

    3. 2.1 Hardware

    The security and access system is composed of three major hardware blocks, namely the sensor circuit, the door and intercom control block and the keypad interface block.

    All these hardware subsystems are interfaced to the computer through the enhanced parallel port, while their status is read through the game port. As a safety measure, opto-isolators are used to link all hardware to the computer. Opto-isolators keep the computer safe from being burned due to back currents and unwanted voltages that might be produced by the external hardware by physically separating their current paths.

    2.1.1 Presence Detector

    The sensor circuit uses a Piezotite Ultrasonic Sensor pair (MA Series) consisting of a transmitter and a receiver. The transmitter, with the aid of a 555 timer radiates ultrasonic waves within 40-48 kHz range and the receiver detects echo of the sound transmitted. The receiver is hardwired with a tone decoder (LM 567) to match up a particular frequency for detection. The transmitter-receiver pair is then setup facing each other across the AIHouse door.

    The system normally outputs a logic low. However, when there is an obstruction between the transmitter and receiver, the sound transmitted by the sensor is blocked off. Hence, the receiver detects no input signal from the transmitter, and generates a high output signal. This output signal enables a flag, which indicates to the main console that there is someone at the door and activates the security and access system. The flag is read through the enhanced parallel port of the computer.

    2.1.2 Door and Intercom Control

    The door and intercom control block is a simple electro-mechanical relay switch circuit, which opens or closes depending on the signal sent by the computer. Implementation of an automatic door lock control system required an additional decoder.

    The door lock is operated by a DC motor, which is controlled to open and close depending on the states of two limit switches positioned along the path of the lock such that the open and close lock states are precisely known. The decoder takes as inputs a command bit from the computer and the states of the two limit switches. The decoder output is then sent to a relay switch circuit, which carries out the appropriate control action, i.e., either to close or open the door.

    Table 1 shows the decoding for the control submodule. Door closed is denoted by ‘x’ set to high, while door open by ‘y’ set to high. ‘z’ is the control bit from the computer, which indicates what control process it should perform, i.e., open door if z is high or close it if z is low. If the output of the decoder is high, the motor moves, while if it is low, the motor stops functioning. To illustrate this, if the door is closed (x = 1 and y = 0) and the control bit from the computer is set to high (z = 1) indicating that door must be opened, output is enabled. This drives the motor. When full opening of the door is not yet achieved (x = 0 and y = 0), and control bit is still enabled, motor should still be activated (output = 1). When door has been opened (x = 0 and y = 1) and with the control bit still high (z = 1), output must be disabled to stop the motor. The over-all result of this sequence of actions is therefore, a change of door lock status from closed to open.

    Table 1. Decoding for door control.

    x

    y

    Z

    output

    0

    0

    0

    1

    0

    0

    1

    1

    0

    1

    0

    1

    0

    1

    1

    0

    1

    0

    0

    0

    1

    0

    1

    1

    1

    1

    0

    x

    1

    1

    1

    x

    2.1.3 Pin Identification System

    The pin identification system consists of inside and outside door keypads. The keypads are used for the filtering of user formants used in speech recognition, inputting the numeric password of the users, which serves as a second level security measure, logging out, and rejecting and accepting visitors.


    2.2 Software

    2.2.1 Speech Recognition

    Speech recognition is implemented using Matlab 5.3. The algorithm used is based on the calculation of formants. Persons who have valid access to the AIHouse are required to train the system to recognize their gateway words.

    This program communicates with the main console through text files. The main console, written in C, creates a text file (start.txt), which contains a single character (by default, the character is 0). The speech recognition program, written in Matlab, continuously reads this text file, until the character is set depending on who is asking for access. This indicates to the speech recognition program that it should prompt for the gateway word, process the speech input and identify if a match occurs.

    After processing, the Matlab program writes a text file indicating if access granted or denied. The main console reads this text file. If access is valid, it requests for the pin number of the person as a second level security measure. If invalid, the person is denied access to the house.

    2.2.2 Main Console

    The main console is written using Turbo C++ v. 3. Its executable form is a DOS based program, requiring minimal computer resources. It features a manual control system, which opens and closes the door, switches on and off the intercom, allows the users to internally change their passwords, the time intervals between automated processes, and the settings of the whole system.

    The whole system is primarily implemented by sampling and determining the state of the status flags as set by the different subsystems.

    External events set or reset different flags, which are the door status, intercom status, presence detector status and manual door control status. These flags are read via the game port. They determine the control action that the system must perform.

    2.2.3 Link to Central and Logging system

    All events are logged into a text file that is submitted to the central computer, which determines what control action each subsystem in the AIHouse must do. Every event is time stamped and is appended to the text file.

    The main console signals the central computer whenever a new event is available to be displayed and logged on to central status monitor. Possible access events that are logged include entries and exits of different valid house occupants and visitors, illegal password occurrences, denied access attempts, and visits that occurred while no one is in the house.

    During emergency situations, such when an invalid access attempt is detected, the corresponding status flag is sent to the central computer, with an emergency flag. These emergencies are reflected and solicit appropriate action through the status monitor of the central computer.

    The main console acknowledges control actions from the central computer. For instance, if both speech and keypad accesses are down, the door can still be opened from the outside by a higher level security option, which contacts the central computer to automatically open the door. This is done by checking the existence of a new command from the central computer at the start of every program loop. Whenever there is a new command, the main console executes the given command first and proceeds to normal operation after.

  3. RECOMMENDATIONS

    This project can be improved by providing an uninterruptible power supply with enough power rating to support all the control systems of the AIHouse.

    The speech recognition algorithm can be transcribed and written entirely in C or an open-source code on formants may be used.

    This speeds up the implementation of the speech recognition, since DOS implementation is faster than Windows-based applications. Furthermore, it cuts down on overhead cost introduced by MatLab.