Current collaborative augmented reality (AR) systems establish a common localization coordinate frame among users by exchanging and comparing maps comprised of feature points. However, relative positioning through map sharing struggles in dynamic or feature-sparse environments. It also requires that users exchange identical regions of the map, which may not be possible if they are separated by walls or facing different directions. In this paper, we present Cappella11Like its musical inspiration, Cappella utilizes collaboration among agents to forgo the need for instrumentation, an infrastructure-free 6-degrees-of-freedom (6DOF) positioning system for multi-user AR applications that uses motion estimates and range measurements between users to establish an accurate relative coordinate system. Cappella uses visual-inertial odometry (VIO) in conjunction with ultra-wideband (UWB) ranging radios to estimate the relative position of each device in an ad hoc manner. The system leverages a collaborative particle filtering formulation that operates on sporadic messages exchanged between nearby users. Unlike visual landmark sharing approaches, this allows for collaborative AR sessions even if users do not share the same field of view, or if the environment is too dynamic for feature matching to be reliable. We show that not only is it possible to perform collaborative positioning without infrastructure or global coordinates, but that our approach provides nearly the same level of accuracy as fixed infrastructure approaches for AR teaming applications. Cappella consists of an open source UWB firmware and reference mobile phone application that can display the location of team members in real time using mobile AR. We evaluate Cappella across mul-tiple buildings under a wide variety of conditions, including a contiguous 30,000 square foot region spanning multiple floors, and find that it achieves median geometric error in 3D of less than 1 meter.

A problem that many tech companies face today is that many computer science students entering the work force lack fundamental skills for understanding the entire process of a system that is not solely software. Some students may take a series of courses on analog and/or digital circuits, but the integration with modern devices is sorely missing from most curricula. We designed the Tufts University Comp 50: Wearable Devices course to introduce the basics of digital and analog circuits to students with software-driven backgrounds by studying the intricacies of the production of wearable electronic devices. The course focused on the skills needed to design hardware, software, and a chassis for a final wearable product that was novel and potentially marketable. The primary objective was to provide a course that serves as an introduction to digital electronics but with a tangible goal to produce a high-fidelity prototype that student teams presented at the end of the semester. Given the nature of modern wearable devices, which are small, energy efficient, and strongly favor connectivity to other devices, we developed the curriculum around designing a surface-mount Printed Circuit Board (PCB), and we outfitted the student kits with coin-cell battery powered, Bluetooth-connected, Arduino-compatible devices that they needed to learn how to program and connect. We also integrated iOS development into the course so that students' final projects could communicate with both their phones or tablets, or to the Internet via these devices. As the "wearble devices"' field is relatively new, this paper discusses the decisions we made for the set-up of this class, what worked and what did not, and what we would change and improve when we teach it again.