USER INTERFACE MODULE

User interface module

User interface module

USER INTERFACE PROTOTYPE

The user interface prototyped in this study is designed around the dynamic route list concept mentioned in the previous section. In addition it incorporates a variety of features that add to its overall ergonomic effectiveness. Figure 1 illustrates a sample instruction in the user interface we developed. The prototype is designed with screen dimensions matching those of typical PDAs on the market today. The sample direction given shows several important aspects of the interface. The arrow labeled “A” points to the area of the screen that is used for basic egocentric directions. These instructions are presented in the largest font in the interface, as they are likely to be the most useful to a user. In addition to a text prompt like “TURN LEFT” it incorporates a dual encoding of the instruction using a corresponding left arrow icon. Basic icons for the four cardinal directions and the four diagonals are easily portrayed. Not all navigation on a campus is as easy as “turn left” and “turn right,” however. The interface allows for more advanced or composite directions and their corresponding icons. Figure 2 illustrates a more complicated instruction telling a user to cross the street immediately ahead of him or her.

The proposed interface supplies numerous features beyond the basic navigational instructions. Arrow “B” in figure 1 points out additional context instructions given for each basic prompt. In this case, it helps clarify not only the direction to turn, but it also gives additional information about the exact location of the place to turn. This affords system designers a means of communicating both exocentric and landmark information. Combined with the basic instruction and icon, the triple coding of data helps ensure the desired message is interpreted correctly.

In this example, the system also has additional data about one or more items in the instruction, specifically the Physics Hall and Science 1 buildings. Hyperlinks are used to denote such situations and can be “clicked” to obtain information ranging from a picture of the building to a list of offices and services within that building. Arrow “C” from the same figure directs attention to the six physical buttons located at the bottom of the PDA. While models vary, most PDAs on the market today have anywhere between four and ten hardware buttons in a similar position as those on the prototype.

These buttons can be used for a number of purposes other than those originally intended. During the navigation phase, there are certain tasks that are most crucial to the device's operation. Intelligent utilization of these hardware buttons is especially important for the Expert Guide. If tasks are inappropriately assigned, a higher dependence on a stylus pointing device could result. This could have significa easily lost while walking around campus. From left to right, the prototype's four main buttons do the following: view the previous instruction (similar to the back button in an internet browser), show a top down “You Are Here” map of the ...