Education & Training Editor: Scott F. Midkiff ■ Virginia Tech ■ [email protected] Wearable and Ubiquitous Computing Tom Martin EDITOR’S INTRODUCTION ture and thickness of the user’s device primarily depends on the relative power This issue’s column continues its coverage of innovative courses in pervasive computing. consumption and expense of computa- Tom Martin of Virginia Tech describes a course on wearable and ubiquitous computing that tion, communication, and local storage. he developed and has taught twice. He describes the course’s scope, assignments and grad- Because wearable and ubiquitous ing, and design projects and his experiences with them. Please send me your comments and computing systems face significant suggestions for future columns. —Scott Midkiff power consumption challenges, the course spends a good amount of time on low-power design and system-level irginia Tech has offered a course on • User input/output devices power management. These topics are V wearable and ubiquitous comput- • Location and context awareness also some of my main research areas ing in the Bradley Department of Elec- • Application case studies and let me connect teaching and re- trical and Computer Engineering twice: search. I begin this section of the class one at the senior or master’s level in The wearable and ubiquitous com- with the power consumption mecha- spring 2002 (15 students) and another puting overview begins with Mark nisms in digital CMOS (complementary at the master’s level in spring 2003 (11 Weiser’s papers from the early 1990s1–2 metal-oxide semiconductor) circuits and students). The course aims to provide and more recent articles by Mahadev then move on to higher-level power students with an appreciation of current Satyanarayanan3 and Thad Starner.4–5 management problems, such as dynamic wearable and ubiquitous computing These provide a road map and motiva- CPU speed-setting, low-power compi- research issues and give them hands-on tion for topics covered later in the lation and source code modification, design experience. The course features a course. The papers also give the stu- and power management state transition group project (see the related sidebar) dents an historical perspective about the strategies. We also spend time studying that reinforces the readings and lectures. evolution of the research issues since batteries—particularly characteristics of The project also teaches students about Weiser’s early work and about advances various battery chemistries and battery the design process in general, including in hardware and wireless networking. life estimation. refining a specification, partitioning Many of the students are in their early functionality, creating interfaces between twenties. For most of their lives, cell subsystems, working in teams, and plan- phones and personal digital assistants QUICK FACTS ning their work. have been widely available, and proces- sor clock speeds have been measured in Courses: ECE 4984 and ECE 5984, COURSE BACKGROUND hundreds of megahertz and main mem- Wearable and Ubiquitous Computing The course comprises about 25 lec- ory in hundreds of megabytes. They Department: Electrical and Computer tures covering have heard about Moore’s Law, but this Engineering is their first concrete lesson in its con- Institution: Virginia Tech • A wearable and ubiquitous comput- sequences. Another major lesson from Instructor: Tom Martin ([email protected]) ing overview these papers concerns the interdepend- Level: Undergraduate and graduate • Low-power design and power ence of the user’s personal device and URL: www.ece.vt.edu/~tlmartin/ece5984_ management the infrastructure available in the user’s wearable • Hardware case studies environment. The required infrastruc- 8 PERVASIVEcomputing Published by the IEEE CS and IEEE ComSoc ■ 1536-1268/03/$17.00 © 2003 IEEE Case studies of the Itsy6 and the IBM SAMPLE PROJECT DESCRIPTIONS Linux wristwatch7 unite many of the low-power issues. Itsy’s main design goal was high performance with low The group design project aims to give students hands-on experience designing a wearable power consumption, so a large research and ubiquitous computing system and to teach them about aspects of the design process community would find it useful; size that will help them with any computing system’s design. Here I give some representative sam- was a secondary consideration because ple project descriptions. of the PDA form factor. However, size drove the IBM Linux wristwatch’s de- Wearable computer front-end for emergency response wireless network sign because of the form factor. IBM When responding to a disaster, you must keep track of emergency personnel and transmit also wanted an intuitive user interface timely information in the field. In this project, students should create a front-end system such in an aesthetic package. Consequently, that someone in the command center will have a map showing the locations of all personnel the two research prototypes illustrate and be able to select an individual on the map to communicate with them or find out about the trade-offs that designers can make that individual’s environment. The individual will have a body or head-mounted video cam- between computational performance, era, a microphone and headset, and perhaps other sensors (for example, temperature, oxy- power consumption, and physical size. gen, and physiological). Another major problem wearable com- A project by-product should be a product-feature matrix for commercially available wear- puting faces is the impracticality of tradi- able computers that will suit this task. tional user I/O devices such as screens and keyboards. The lectures cover alternative Camera for historical surveys forms of interaction, including tactile dis- Before beginning a major construction project such as a road, the construction company plays, manipulative user interfaces, and must perform a historical survey of the area where the construction will take place. This survey movement-aware clothing. I also ask stu- documents any structures and features that might have historical significance. Currently, an dents to use an alternative text input inter- individual takes field notes by hand describing the location and structure details and takes face, Dasher (www.inference.phy.cam.ac. photographs of the structure and surroundings. Back in the office, the individual locates the uk/dasher), and compare it to typing and structure on a map, types the notes, and integrates the photographs into the notes. The sur- writing by hand. veyor then enters this into a GIS (geographic information system) and perhaps creates a com- Several of the user I/O devices provide puter model of the landscape. a smooth transition into context-aware- The project should create a historical survey device for a digital camera that records the ness because they can be sensitive to user photograph’s location and the direction it was taken from. The device should automatically actions that are explicitly meant to be place the photograph on an electronic map of the area. input or to implicit actions that an appli- cation can use to infer the user’s current Ultrasonic building-mapping garment context. For example, an explicit action This project aims to model and create an electronic-textile garment that maps a building as would be a hand signal that tells a stereo the user walks through it using ultrasonic emitters and detectors, and perhaps other sensors to lower its volume, while an implicit facing in all directions. The device should be able to estimate the distance to objects in all action would be walking upstairs. Con- directions (within a certain range) and create a map of the areas (of a building) that a user has text-awareness involves knowing the passed through. The system should account for the user’s movement (it might be necessary user’s location, activity, companions, to stand at an entrance to create an initial registration point). and nearby resources. Without context- Students should model the garment in Ptolemy (www.ptolemy.eecs.berkeley.edu) in two awareness, a wearable computer will dimensions. The model should take as input a floor plan and a path through that floor plan, only distract the user, and a ubiquitous and output the garment’s map along the path. The model must account for the ultrasonic computing environment will offer little sensors’ physical properties. Students should use the model to answer questions such as benefit. The course lectures discuss im- plementations using various types of •What are the algorithms for mapping and feature detection (for example, walls, corners, sensors (for example, accelerometers, and openings)? magnetometers, omnidirectional video • How many ultrasonic emitters and detectors do you need? How should you place them on cameras, and microphones) and post- the body? How does the generated map’s accuracy vary with the number and placement processing. We also discuss location- of emitters and detectors? awareness, particularly methods for • What information do you need about the user’s movement (for example, velocity and rates determining location indoors. of turning)? The remaining lectures comprise Continued on p. 10 application case studies. These case JULY–SEPTEMBER 2003 PERVASIVEcomputing 9 EDUCATION & TRAINING EDUCATION & TRAINING SAMPLE PROJECT DESCRIPTIONS (cont’d) I also provide a few supplemental read- ings. This exposes many students to extensive readings from the research lit- Continued from p. 9 erature for the first time. To help them with their reading, I require them to Electronic buttons for e-textiles write a brief summary of each paper, This project aims to devise a method for reliably and cheaply connecting a printed circuit submitted via email at the beginning of board button to a textile. Soldering alone won’t suffice due to mechanical problems and the week. I also ask them to submit a list other incompatibilities. Even if you could solder, you’d still have to line up the button’s con- of questions about the readings, which I nections with fabric’s threads.