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Mobile Application Model for the Blind

2007, Lecture Notes in Computer Science

This study presents a model to design and implement mobile applications to support the displacement and dynamic decision making of users with visual disabilities. To identify the real added value of using mobile technologies as support aids for decision making in dynamic contexts for users with visual disabilities, we provide an application case. By using a graph to represent the computer model of a real school for blind children, for whom a system was already developed using our model, we provide a real example application of this model. This provided enough input to enrich, improve and redesign the model; ending up with a usable mobile application model to assist the mobility and orientation of blind users.

Mobile Application Model for the Blind Jaime Sánchez, Mauricio Sáenz, and Nelson Baloian Department of Computer Science University of Chile {jsanchez,msaenz,nbaloian}@dcc.uchile.cl Abstract. This study presents a model to design and implement mobile applications to support the displacement and dynamic decision making of users with visual disabilities. To identify the real added value of using mobile technologies as support aids for decision making in dynamic contexts for users with visual disabilities, we provide an application case. By using a graph to represent the computer model of a real school for blind children, for whom a system was already developed using our model, we provide a real example application of this model. This provided enough input to enrich, improve and redesign the model; ending up with a usable mobile application model to assist the mobility and orientation of blind users. Keywords: Mobile, learning, model, software, blind learners. 1 Introduction The massive use of mobile tools in every life has motivated researchers and implementers to design software applications in order to provide users with high demand data processing services always available including useful and upgraded information. Diverse efforts have been made to give accessibility to these applications for users with visual disabilities. Diverse applications have offered critical improvements in accessibility [7], [20] and learning [5], [9], [14], [11], [17] for users with visual disabilities. However, these applications have been designed for users in a rather static working context without integrating dynamic and upgraded information about the surrounding area. The world around us changes constantly with irregular situations that modify and alter it through time. Sighted people can easily order the environment through the use of the visual sense, but people with visual disability can hardly make decisions when unexpected situations occur. Thus, the development of technology for users with visual disabilities should imply user-centered methodologies, identifying clearly interaction modes and their immediate consequences in the user’s performance. Educational software for people with visual disabilities usually lacks of critical interface elements commonly present in software for sighted children. Most software does not include things such as explicit model knowledge and skills learners to be enhanced when using the software, explicit learner model, and appropriate feedback to improve the learners' performance. To many authors, designers of educational C. Stephanidis (Ed.): Universal Access in HCI, Part I, HCII 2007, LNCS 4554, pp. 527–536, 2007. © Springer-Verlag Berlin Heidelberg 2007 528 J. Sánchez, M. Sáenz, and N. Baloian software for children with disabilities conceive the software with interaction constrains in their minds, fixing the interaction modes from the very beginning. Educational software for learners with visual disabilities should design without considering from the beginning the users' disabilities. Rather, they should take into consideration aspects such as a model representing existing or artificial interacting world, a model for representing the knowledge to be learned, and model for the learner. The learner’s capabilities and disabilities should be considered when mapping inputs and outputs of the model into an interface. Since educational software development depends on people, tools, and methodologies involved, and considering there is no a clear methodology to carry out this process for children with visual disabilities, the results mainly depends on the skills of the involved people. This situation can cause many drawbacks typical of a handcrafted process. Rather, software engineering uses methodologies to help to reduce the craftsmanship level of software development by using the best methodological practices. The navigation of blind users in real environments exposes them to higher risks than sighted users because they cannot use the physical cane to help them to identify objects in the space. For this reason, some cues should be provided to users with visual disabilities to get a more reliable mobility, allowing them to access to richer information from the environment [4],[5],[6]. Then, it is necessary to extend the model to mobile contexts, to allow designer to create educational software for mobile devices. We present a model that extend the process model already described in Sánchez et al. [10],[13], by instantiating it for mobile contexts. This extension involves users with visual disabilities in contexts and situations behaving autonomously. Thus, through the support of digital technology they can define strategies to solve problems that sighted users can solve rapidly by using their vision input. 2 Related Work Burgstahler [1] proposes a way technology can be used by learners with visual disabilities, allowing them independence, productivity, and participation in academic activities and everyday life, proposing the following ways technology can provide to people: (a) Gain access to the full range of educational options, (b) Participate in experiences not otherwise possible, (c) Succeed in work-based experiences, (d) Secure high levels of independent living and (e) Work side-by-side with peers. Roschelle et al. [8] recommend avoiding a process of software development centered on just software professional by including multidisciplinary teams in the design and development, concentrating in specific domain aspects. The main idea is to produce specific domain software components to better manage the expected results of educational software. We have described elsewhere a model for educational software for people with visual disabilities [13]. It is mainly based on tasks to be solved by the user. The model consists of the stages of analysis, design, development, and validation (see Figure 1). Analysis. Cognitive goals to be achieved by the learner are designed as well as the definition of software requirements. Cognitive evaluations define procedures and Mobile Application Model for the Blind 529 functions to evaluate the achievement of cognitive goals. Design. A metaphor is defined for a virtual environment or scenario where the learner constructs knowledge through interaction within the virtual world. Normally, this is gaming software so the playing rules are defined. All of this leads to define the model of the virtual world and the knowledge to be constructed. Development. This stage implies three subprocesses: first, the computational implementation of models of the world and learner, second, the implementation of the evaluation process and feedback to the student, and third, the projection of the models. It is important to implement these actions after setting the model to avoid constraining from the beginning the software design. Validation. This stage consists of two sub-processes. First, we develop usability tests to gather data about how well the system fit our objectives in order to attain the cognitive goals set at the beginning. In this stage, the emphasis is on the analysis of some elements of human-computer interaction. Second, we analyze these results and study how the metaphor, models, and the projection of input/output variables can be improved. An error in the integrity of the system for learning can imply to review the metaphor and models used. Usability issues can lead to review the projection. Fig. 1. Schema of model for educational software [10] Diverse intents have been made to adapt mobile devices to the requirements of users with visual disabilities, obtaining hardware prototypes oriented to specific users. For instance, a pocketPC specially targeted for blind people contains screen readers with buttons instead of a tactile screen [3]. Wobbrock proposes the use of specific hardware to complement the features of standard pocketPC. However, this adaptation has two major constrains: the high cost and the loss of mobility when using the mobile device. Sánchez and Aguayo [12] emphasize the development of two interface modules to allow interaction with a pocketPC by users with visual disabilities. The first is the input module consisting in a virtual keyboard of nine buttons placed on the tactile screen of the device, letting users to write in the same way as they do with their 530 J. Sánchez, M. Sáenz, and N. Baloian cellular phone without needing external devices. The second is the output module based on a text-to-speech engine adapted to the user needs. AudioStoryTeller [15] is a pocketPC application to support the development of reading and writing skills in learners with visual disabilities through storytelling, providing diverse evaluation tools to measure these skills. This software application has been implemented through auditory interfaces to support actions and provide feedback. Software for a pocketPC, mBN [16], contains a metaphor that represents a simulation of a subway travel through a wagon. Travels are developed in a logical way without considering spatial representations of virtual spaces. The metaphor considers notions of consecutive stations, transfer stations, and terminal stations. Interaction is achieved by using the corners of the pocketPC screen, joining the adjacent points. Hence, the software watches, analyzes and interprets the movements of the pointer without special devices. The system PGS (Personal Guidance System) proponed by Loomis [2] was developed as an outdoor navigation tool depending completely on a GPS. The system provides instructions to mobilize from one point to the other through verbalized instructions and descriptions by using dual earphones. The navigation and guidance system NOPPA [19] is oriented for blind user to travel through the city without interruptions by using buses, trains, and walking. It is based on a client-server architecture accessing to information through internet from a terminal. Information is communicated through voice synthesizers. In [2] is presented PINS (Personal Indoor Navigation System), an indoor navigation system to provide an independent and efficient navigation to users with visual disabilities. The system allows to solve navigation tasks and route plans, but is does not include obstacles avoidance. PINS use a positioning and orientation system, a spatial data base and a user interface. The input of information is through audio and a Braille keyboard, allowing the downloading of navigation maps when entering to a place. Other aids include tactile maps that through talked voices provide directions. These maps have low resolution, hard to get and use while the user is moving, so they don’t solve users’ orientation problems [20]. Finally, a related work was done by Sasaki [18], presenting how mobile technology can support mobility and orientation of visually impaired users when utilizing public transportation buses. 3 A Model for Developing Mobile Applications for Blind People The need for models to develop educational software has already been recognized in order to generalize and replicate good practices. We have designed a model for developing software for mobile devices targeting people with visual disabilities when learning how to mobilize more efficiently to accomplish certain tasks in a known area (see Figure 2). This model is based on the initial model presented in chapter 2 [11] aiming to develop educational software for people with visual disabilities. Since our goals are focused on software for the mobile scenarios we can instantiated the model for mobile purposes and make a detailed description of its parts. Mobile Application Model for the Blind 531 Fig. 2. Mobile Application Model The model itself is a workflow consisting of four principal phases: Analysis: This phase takes as input the learning goal of the application. This learning goal will define the cognitive tasks the learner should acquire by using the system. Based on these cognitive tasks, we can specify the concrete tasks the user has to perform with the help of the system in order to reach the learning goals. The cognitive goals established in this phase will be later used to produce the metrics in order to evaluate the correct achievement of these tasks and will serve for validating the application in its effectiveness. Modeling: In this phase the tasks supported and the environment are modeled. The main product of this task is the Model. It is the computer’s internal representation of the knowledge the user has to acquire. For the mobile case, this is the real world including the environment in which the user should move and all the relevant information needed to accomplish the tasks defined in the previous phase. A good way to computationally represent such an environment is using a graph. In such a graph the nodes are called spots, and represent only the relevant objects of the environment the user can recognize (a corner, a booth, or even a trash bin if relevant) which can be used by the user to recognize the place. The links of the graph are called ways, including relevant information about the characteristics of shortcuts paths to go from one spot to another. The type and amount of information of ways depends on the kind of the cognitive task the system is assisting the user to accomplish. In some cases, relevant information may be the distance between spots measured in meters, or 532 J. Sánchez, M. Sáenz, and N. Baloian the average time a user would take to go from one spot to the other. In other cases a number identifying the user’s degree of confidence to cover the distance or the safety degree of walking through that way may be useful. (see figure 3). Fig. 3. An example of a graph representing spots and ways. The values l, d, p, t represent the evaluation of different characteristics of the way, such as the time needed to cover it, the distance, the degree of safety, etc. Having a graph representing the real environment where the user has to accomplish tasks makes it easy for the computer to calculate all possible paths (collection of ordered ways) for moving from one spot to another by applying well known algorithms over graphs like Dijksta’s. Applying different values of the ways as input for the algorithm, we can find different kind of paths between two spots. For example, using the distance value we can find the shortest path, using the time value we can find the faster path. Moreover, the system can find the best path for a combination of safety and speed by giving weights to these numbers. As already described in [2] a very important issue of the modeling phase is to establish the state, input, and output variables. State variables are those describing the state where the user is. A very important state variable of the model is the user’s current position, which can be on a spot or on a way. The mechanism to update this variable depends on the environment where the user moves and the resources available. Whenever the distances are long enough, a GPS mechanism can be used. The user must update this variable otherwise. Input variables are those received from the user and/or the environment to update the state variable. Output variables are those used by the system to provide relevant information to the user. The model component should also include a user model. A user model is the information the system uses to compute what the user knows, does not know, and if the user has wrong knowledge about something. With this information the system should be able to assist the user providing the right information at the right time to accomplish the task. For the mobile case, the simpler, yet most effective way to implement a model of use is using the overlay technique. In this case, an overlay user model will be a graph containing the collection of spots and ways he or she already knows. Figure 4 shows the graph representing the computer model of a real school for blind children in Santiago, Chile, for which a system was already developed using this Mobile Application Model for the Blind 533 model. The ways and spots belonging to both, the user’s model graph and the computer’s knowledge representation graph, are shown in white color. The ways belonging to the computer’s graph are shown in black Fig. 4. The figure shows a scale model of the school for blind children and both graphs for implementing the computer’s knowledge model (all nodes and lines) and the user’s model (only white lines and nodes) The user’s model can be initialized with the graph representing the spots and ways the user usually uses to move from one point to another. It should also be updated when the user uses a new way between two spots. This represents a learning step of the user. By overlaying the user model’s graph to the one representing the computer’s knowledge, it easy for the system to decide whether at a certain point it can provide useful information to the user. The system computes the most convenient path from that point to the target arrival point. If the first way in the path is not on the user model, the system can provide this information to him or her. Development: Graphs along with algorithms and procedures are implemented. The methodologies and procedures for evaluating the user’s performance are also developed. The evaluation methodologies will depend on the cognitive tasks supported by the system. For example, if the original task is to find the faster way between two places, the evaluation should consider the time invested by the user and compare it against the “normal” time an average user will need when using the fastest path. If the task is to find the shortest path, then the system will have to consider the length of the path used and contrast it with the shortest path the system can compute using the algorithms. The projection component of the development phase is the process of mapping input and output variables on proper input and output devices of the mobile computing device. Since mobile devices have more restricted possibilities for good input and output, especially for people with visual disabilities, in most cases, the input variables will be mapped on haptic devices (such as buttons or keys) and the output devices on audio signals. Considerations that should be regarded for 534 J. Sánchez, M. Sáenz, and N. Baloian implementing these projections are described in [1] for the non-mobile scenario. In the mobile scenario we should also consider that audio output must be even clearer and concise because of the presence of environmental noise. Validation: During the validation phase the usability and effectiveness of the software is evaluated. The usability is for the user’s acceptance and how well he or she interacts with the model. This will depend on how good input and output variables of the model have been projected on the input and output possibilities available for a mobile case. The effectiveness is evaluated by finding out the user’s performance with and without the application. The first step is it to define the tasks evaluation strategies and methodologies in accordance with the tasks defined in the analysis phase. These will in turn serve as input to develop the evaluation methodologies for the user’s performance and at the same time, to evaluate whether the system makes a contribution to the performance of the user. 4 Conclusions This study introduces a model for implementing mobile applications for users with visual disabilities. We have also provided an application example by using a graph to represent the computer model of a real school for blind children, for which a system was already developed using our model. We are implementing a research study to applying this model to real mobile cases such as the subway, neighborhood, and the school. The result of this new study will validate more fully our model for designing mobile applications for decision making in dynamic contexts. The use of mobile applications should not be reduced to sighted users even though the whole interface is thought for their mental models. There is no need for producing devices specially tailored for them that have a high cost because of the limited target population. The design of interfaces to provide efficient input/output access and interaction is sufficient to exploit the potential of these devices in the everyday life of blind users. Software applications should be implemented specially tailored for users with visual disabilities. It is not enough to adapt existing software; rather there is a huge need for software specially tailored for the needs and mental models of users with visual disabilities. This will allow these users to take advantage of the benefits of pocketPC devices closing the gap between the unique features of mobile technologies and the actual use by these users. The model proposed here allows designing diverse applications to help users with visual disability to improve their mobility and orientation skills in everyday contexts. The availability of a mobile aid that provides information about shortcuts and efficient ways and routes, helps them to mobilize efficiently and autonomously in different scenarios and thus helping them to become more socially included. Acknowledgements. This report was funded by the Chilean National Fund of Science and Technology, Fondecyt, Project 1060797. Mobile Application Model for the Blind 535 References 1. Burgstahler, S.: The role of technology in preparing youth with disabilities for postsecondary education and employment. 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