Extending Sensing Capabilities and Modalities of Mobile Devices

Thesis (Ph.D.)--University of Washington, 2014Mobile devices have a variety of built-in sensors (e.g., accelerometer, gyroscope, GPS, camera etc.) that allow them to be used in a wide range of context-aware mobile applications. Additionally, their built-in communication interfaces - like WiFi, Bluetooth and USB - let them communicate with external devices and sensors. Using built-in and external sensors, mobile devices help bridge the physical and digital worlds by providing precise readings on various natural phenomena (e.g., environmental and soil conditions). Creating mobile sensing applications poses the following challenges for developers: * Sensors often have only low-level communication interfaces; hence, an interfacing board is needed to connect them to mobile devices. * Partitioning a sensing application between a mobile device running an OS like Android or iOS and an interfacing board that likely has an embedded OS at best, adds complexity to the system. * In addition to implementing application logic, developers must overcome the quirks of different physical communication channels and process sensor-specific data. My thesis addresses these challenges by: (1) extending the sensing capabilities and modalities of mobile devices, and (2) simplifying the development of mobile sensing applications. To this end, the thesis makes the following contributions: * Hardware to enhance and simplify a mobile device's ability to connect to various types of sensors * A software framework to simplify development of mobile sensing applications * Implementation and evaluation of sensing systems to enhance workflows in low-resource settings The research leading to my thesis explored different hardware options to interface low-level sensors to mobile devices of varying capabilities, ranging from low-tier, non-programmable phones to smartphones and tablets. I developed the Open Data Kit (ODK) Sensors framework for Android devices to simplify the development of mobile applications that interact with sensors. Using sensor interfacing boards and ODK Sensors as building blocks, I developed applications that have been deployed to address critical global health issues in developing countries. Further, the general-purpose technology building blocks are now being used in a variety of mobile sensing applications