Implementation of wireless sensors based home monitoring system

In this paper we present the details of a system that has been designed and implemented to non-invasively monitor old people living by themselves in a home. The system works by monitoring the usage of electrical as well as non-electrical equipments in the home. A sensor unit (SU) is required for each device that needs to be monitored. It detects when the device is active (i.e. in use) or inactive. Rules are defined in the software for the devices to turn on or off in certain time intervals. When a defined activity does not take place within a time window or does take place outside a set time limit, an alarm is generated. The SU communicates with a central controller unit (CCU) using radio-frequency wireless media to report the status of the device. The rules are flexible and can be user-defined based on the daily activities of a person. The rules inference engine runs on the PC and whenever the situation requires, sends a text message to the mobile cellular phone of the care-givers or relatives. Since no camera, motion sensors or infra-red detectors are used the system is non-invasive and respects privacy. Any number of sensor units may be installed in a house and the system is completely customizable, allowing the user to select which appliances to monitor.