Pervasive Visual Sensor Networks for Elderly Care

The proportion of aging population in human society is demonstrating a remarkable increase every year. Our society faces the following challenges to deal with this in crease in the aging population: more investment is needed for elderly care and the decrease in the working population will cau se a shortage of skilled caregivers [1]. Therefore exten sive research efforts take place on developing smart car e systems. The state of the art solutions for smart elderly ca re systems include video monitoring and wearable devices. In v ideo monitoring, or camera-based surveillance, the camer s independently and continuously transmit video strea ms to a central processing server. Captured video is analyz ed by a human operator, or it is stored in a database for l ater processing. This solution requires a considerable a mount of man-power to monitor all the activities and may vio late the privacy of the elderly when their activities are co ntinuously monitored. Wearable devices with the capability of raising alarms when the user is in trouble may include a we rable with a button that needs the elderly to raise an al rm [1], or a wearable that is equipped with motion detectors (accelerometers, etc.) and raises an alarm when a d angerous situation is detected, such as a fall [2]. However, the efficiency of the wearable systems is limited by th e willingness of the elderly to wear them and to rais e an alarm. An alternative elderly care solution that recently gained attention is to use pervasive smart camera systems or in other words Visual Sensor Networks (VSNs) [3]. VSNs are considered as a subclass of Wireless Sensor Networks and are composed of embedded camera devices. In an elderlycare context, such a pervasive camera system can be depl oyed by placing camera sensors in the living space of the e ld rly to monitor their safety and raise alarms when a danger is detected. Compared to the solutions on wearable dev ices, VSNs are unobtrusive and non-intrusive to elderly life and compared to continuous monitoring, VSNs respect the privacy of elderly since they start recording if a danger i s detected. Although some examples of VSN systems for elderly support exist in the literature [4-6], they mostly focus on specific problems, such as fall detection, where th e objective is to demonstrate that even a system composed of lo w-power, low resolution cameras can assist the elderly in a costeffective manner. Moreover, these systems are usual ly deployed with a limited number of cameras in an ind oor setting. In this research, our objective is to take a more comprehensive and multi-disciplinary approach and to find the best tradeoffs between processing and communication components of a VSN system not only deployed in a l imited home environment but also large outdoor environment s, such as a garden of a nursing house, where we can demons trate scalable solutions and where we can benefit from th e self organization characteristics of VSNs. Our research aims to contribute to the following objectives and our post er will present the preliminary ideas on the following: Scalable and Efficient Network Architectures: We will investigate the use of a multi-tier architecture by using different tiers that include different set of nodes with different capabilities, such as movement sensors at the lowest level to detect a person and wake up the upp er tier which includes the camera nodes. Developing Lightweight Vision Processing Algorithms : Many vision processing algorithms are designed for single camera systems and are not optimized for resource constrained cameras. In this context, we will resea rch the algorithms that can be used in VSNs and adaptation issues. QoS-aware Communication Protocol: Our initial focus will be on designing a MAC protocol which brings the abi lity of assigning different priorities to varied users, fra mes, packets and considering their deadlines by controlling the s aring of the wireless medium. Then we will extend our focus to the routing/transport layers by following a cross layer approach to meet the QoS requirements imposed by the applica tion. Cross Layer Resource Optimization in VSNs: We aim for designing adaptive processing and communication algorithms that interact with each other. For insta ce by reducing the amount of data to be transmitted, ener gy consumption at the communication side is reduced bu t on the other hand this may lead to a poor image qualit y nd false identification of events. The number of senso rs to report an event, amount of data to be reported, an access to variable bandwidth medium are all just some exam ple parts of a resource management problem in VSNs.