granted different types of home access based on biometric matches. As described in Scenario 1 of Section
1, some individuals may only have access to the garage or front porch while repair technicians would also
be granted access to areas of the house that need their attention. If an individual manages to enter
unauthorized areas of the house, the homeowner is notified.
Homeowners may choose to let ambient sensors run continuously and use the more intensive data-
gathering devices such as cameras only when they are out of the home. In such cases, Petersen et al. [79]
propose a method to automatically detect these situations and turn on video cameras. In this work, motion
and door sensors continuously collect data and a machine learning system is trained to map these sensor
readings onto a label indicating whether the residents are at home or away from the home. This approach
extracts features including the number of sensor firings during each five-minute interval, an indicator of
whether or not the resident is in bed, whether the door sensor was the last reading in the interval, whether
the door sensor was the first firing in the interval, and whether the last sensor in the interval emanated
from a room connected to an external door. A logistic regressor yielded a sensitivity of 0.939 and a
specificity of 0.975 on sample data collected from actual smart homes, which are strong preliminary
results supporting this approach.
While intrusion detection is a common application for security systems, much of the technology can
also be applied to health monitoring and assistance as well. In the case of work by Dodge et al. [80], by
Hodges et al. [81], by Dawadi et al. [82]
, and by Lotfi et al. [83], unexpected behavioral patterns are
viewed as a health risk for individuals who are at risk of cognitive decline. These researchers have found
that an increase in the number of activity anomalies and variation in behavior patterns such as activity
times and walking speed are correlated with changes in cognitive health. As in the case with the intrusion
detection research, these findings provide insights that can be used by smart homes in order to keep
residents safe. For example, residents and their caregivers can use this information to change the level of
care that the individual needs.
In research by Ali et al. [84] and of Das et al. [85], threats are detected in the form of abnormalities in
how residents perform their daily activities. For many individuals, these variations would not be
considered a risk. However, for individuals with memory limitations, performing daily activities
independently is critical. Functional impairment has been associated with increased health care use and
Figure 2. Technologies found in a secure smart home.