Publication Type

PhD Dissertation

Publication Date



With the prevalence of sensors in public infrastructure as well as in personal devices, exploitation of data from these sensors to monitor and profile basic activities (e.g., locomotive states such as walking, and gestural actions such as smoking) has gained popularity. Basic activities identified by these sensors will drive the next generation of lifestyle monitoring applications and services. To provide more advanced and personalized services, these next-generation systems will need to capture and understand increasingly finer-grained details of various common daily life activities. In this dissertation, I demonstrate the possibility of building systems using offthe- shelf devices, that not only identify activities, but also provide fine-grained details about an individual’s lifestyle, using a combination of multiple sensing modes. These systems utilise sensor data from personal as well as infrastructure devices to unobtrusively monitor the daily life activities. In this dissertation, I have used eating and shopping as two examples of daily life activities and have shown the possibility to monitor fine-grained details of these activities. Additionally, I have explored the possibility of utilising the sensor data to identify the cognitive state of an individual performing a daily life activity. I first investigate the possibility of using multiple sensor classes on wearable devices to capture novel context about common gesture-driven activities. More specifically, I describe Annapurna, a system which utilises the inertial and image sensors in a single device to identify fine-grained details of the eating activity. Annapurna utilises data from the inertial sensors of a smartwatch efficiently to determine when a person is eating. The inertial sensors opportunistically trigger the smartwatch’s camera to capture images of the food consumed, which is used in building a food journal. Annapurna has been subjected to multiple user studies and we found that the system can capture finer details about the eating activity – images of the food consumed, with false-positive & false-negative rates of 6.5% & 3.3% respectively. I next investigate the potential of combining sensing data from not just multiple personal devices, but also by using inexpensive ambient sensors/IoT platforms. More specifically, I describe I4S, a system utilises multiple sensor classes in multiple devices to identify fine-grained in-store activities of an individual shopper. The goal of I4S is to identify all the items that a customer in a retail store interacts with. I4S utilises the inertial sensor data from the smartwatch to identify the picking gesture as well as the shelf from where an item is picked. It utilises the BLE scan information from the customer’s smartphone to identify the rack from where the item is picked. By analysing the data collected through a user study involving 31 users, we found that we could identify pick gestures with a precision of over 92%, the rack where the pick occurred with an accuracy of over 86% and identify the position within a 1 meter wide rack with an accuracy of over 92%. Finally, I explore the possibility of using such finer-grained capture of an individual’s physical activities to infer higher-level, cognitive characteristics associated with such daily life activities. As an exemplar, I describe CROSDAC, a technique to identify the cognitive state and behavior of an individual during the shopping activity. To determine the shopper’s behavior, CROSDAC analyses the shopper’s trajectory in a store as well as the physical activities performed by the shopper. Using an unsupervised approach, CROSDAC first discovers clusters (i.e., implicitly uncovering distinct shopping styles) from limited training data, and then builds a cluster-specific, but person-independent, classifier from the modest amount of training data available. Using data from two studies involving 52 users conducted in two diverse locations, we found that it is indeed possible to identify the cognitive state of the shoppers through the CROSDAC approach. Through these three systems and techniques, in this dissertation I demonstrate the possibility of utilising data from sensors embedded in one or more off-the-shelf devices to determine fine-grained insights about an individual’s lifestyle.


wearable computing, lifestyle monitoring, eating detection, shopping analytics, activity recognition, sensor fusion

Degree Awarded

PhD in Information Systems


Infrastructure | Programming Languages and Compilers | Software Engineering


MISRA, Archan; BALAN, Rajesh Krishna


Singapore Management University

City or Country


Copyright Owner and License

Singapore Management University

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.