Design Principle for Ubiquitous Computing Chen Kai DIUF – Department of Informatics University of Fribourg, Switzerland [email protected] Abstract 2. Design principles Design principles are derived from a mix of theory-based knowledge, experience, the common sense. They tend This paper intends to make a state of the art of design to be written in a prescriptive manner, suggesting to de- principles applicable in the ubiquitous computing (ubi- signers what to provide and what to avoid in the interface comp) domain. Since design principles are well defined, (does and don’ts of interaction design). More specifically, accepted and used in Human-Computer interaction, it is they intend to help designers explain and improve their not the case in ubicomp. We also analyze a concrete ubiq- designs [5]. D. A. Norman [2] has identified the design uitous system project, establish a list of applied design principle which should be consider before creating any principles and check if design principles for GUIs fit to objects with which we will interact in our life. this particular system. In his paper [3], D. Gelbcite has made an overview of Keywords: Design principle, Ubiquitous computing, the main principles defined by Norman: Pervasive computing. • Visibility. To be able to control the object, we have to see their important components. For example, 1. Introduction when we drive a car we should be able to see the state of device and possible action. The car control Since 30 years, the development of computing technol- should be place in a obvious position, so we can ogy has changed drastically our daily life, and the inter- easily found and use them. As a bad example, we action between human and computer has evolved accord- take the auto faucet. It is difficult to use, because ingly. If at the beginning, users were operating the ma- people like me will always try to find the switch to chine only (computer centered design), nowadays they deactivate it. are the center of the problem and computer programs or systems are developed in regards to user’s needs and • Feedback. It’s important to know what the system habits (user center design). The user being in the cen- is doing now. The feedback should be immedi- ter, program and system designers have to think about ate and synchronized with the user action. For in- how users interact with computers and what kind of de- stance, when playing piano, the pianist be able to sign principles should be applied in order to design usable hear the sound when he presses the key. systems. • Affordance. Perceiving the properties of a object In this paper, we intend to specifically present some should give the means of its operation. For exam- design principles for ubiquitous computing (ubicomp) ple, the different shape of the door handle should presented in divers papers. In section 2, we present prin- tell us to push or pull it to open the door. ciples of design every day objects proposed by D. A. Nor- man [2]. In section 3, we show how these principles are • Mapping. Mapping means the relationship be- applied in design the graphic user interface. In section tween controls and their action. For example, the 4, we list some design principles for ubiquitous comput- control of MP3 player has the buttons with direc- ing system found in the literatures. In section 5, we show tion triangles. Just by seeing the direction of trian- a example of the ubiquitous computing system and the gle, we know how to jump to the next song or go design principles which has been applied, and find out back to the previous one. which of the design principles considered in GUI can be applied to this system. In section 6, we draw a conclusion • Constraint. Restricting some interactions can re- about design principles of ubicomp and future work. duce the chance of errors. For example, in the menu list some options are unavailable in some is that they are easier to learn and use. Users have moment context. to learn only a single mode of operation that is ap- plicable to all objects. • Consistency. The interfaces which have similar op- erations should be consistent. For example, the • Affordance. It is a term used to refer to an attribute power on buttons are similar in different devices of an object that allows people to know how to or the access to menu are always the same. use it [5]. For example the graphical elements like icons should be designed to afford clicking, scroll- In next section, we introduce how these principles are bars to afford moving up and down, buttons to af- applied in graphic user interfaces. ford pushing. 3. Design principle for graphical user • Mapping. J. Hobart calls it Provide Traceable interface Paths which means users should be able to know how to go to a window, how to achieve some func- In the previous section, we have seen the main design tions. principles for everyday objects. Now we present how these principles are applied specifically in the graphical • Simplicity. Keep the important and interesting el- user interfaces (GUI). ements in the screenful space. Getting the bal- To make the program more user friendly, user inter- ance between aesthetic appeal and simplicity[4]. face must be intuitive and easy to use. In the paper ”Prin- Google is a good example, the interface contains cipals of Good GUI Design”, J. Hobart [4] has shown the only the necessary elements (e.g. the text field and causes that contribute to a bad design: button) to achieve the task. In the next section, we present some design principles • Forgetting user identified for ubicomp systems. • Failing to Give user control 4. Design Principle for Ubiquitous • Providing to many feature at the top level computing In [5] (ch. 1.6), they identify Norman’s design prin- The concept of ubicomp has been developed in the 80’ ciples applicable specifically to GUI: by Marc Weiser and stated that computers will be every- where, disappear into our environment and will be em- • Visibility. Intuitive position of control components bedded into everyday objects [1]. like buttons and switches in the GUI can help user In his vision, Weiser predicted a radical change of to use the program more easily instead of guessing paradigm in computer sciences passing from ”many users how to make it work. - one computer” to ”one user - many computers”. Also • Feedback. To be able to know what has been done ubicomp will allow to access information every time and and how to continue, the user need a feedback. everywhere. For instance, during a backup operation, the user This new paradigm force us to redefine the interaction would appreciate to know the remaining time in or- mode with such systems and reconsider the design prin- der to organize his time. J. Hobart [4] states that in ciples that should be applied in order to create usable, general, most users like to have a message dialog intuitive, secure computing systems. box with a progress indicator displayed when op- We have found several papers describing design prin- erations are going to take longer than seven to ten ciples. It appears that there are general principles which seconds. cover everything in every domains as it is the case for GUI for instance. In the field of ubicomp, there are more • Constraints. Constraints means to restrict certain different approaches which not necessary overlap. We kinds of user interaction. The advantage is that it have selected only the paper describing what we consider reduce the chance of making mistakes. A common to be relevant principles. design practice in graphical user interfaces is to de- activate certain menu options. 4.1. Computer system issues • Consistency. J. Hobart shows a good example of In the paper ”Pervasive Computing: Vision and Chal- consistency in software development. Suppose we lenges” [8] M. Satyanarayanan et al. show the de- are writing the business application, we should pro- sign principles in computer issues. At the beginning vide the user with consistent behaviors. The busi- the authors present the evaluation of computer system. ness users of your software always have the similar The ubiquitous computing environment is saturated with needs. In GUI, the benefits of consistent interface computing and communication capability. The difference between ubiquitous systems and other computing sys- system is to fit user’s requirement, therefore the worker tems is that they become integrally part of people’s life, does not have to know what happen in the background. and is ”invisible”. Ubiquitous systems contain the princi- So they can focus on their work and increase the effi- ple of distributed system and mobile computing system. ciency. But in educational context, the goal is to interest They include the problematic of: the students. If the technology is completely invisible, then people don’t know how it works and that will de- • Remote communication crease their curiosity. That is why they present three cen- • Distributed security tral themes for ubiquitous education computing. • Mobile networking 4.2.1. Curiosity Enhancement • Location sensitivity ”Ubiquitous Computing as a Means of Conveying Besides those concerns, ubicomp contains the addi- Ideas”. To motivate the students, we need to increase the tional principles: curiosity of the objects with which they interact. For that, people should be able to design, program, customize the 4.1.1. Effective use of Smart Spaces objects. The authors show their lab to show how to argu- ment the curiosity. Their project is called ”SmartTiles”. The smart space could be an enclosed area, for example SmartTiles are tiles-like pieces which contains a micro- classroom, meeting room.