Phantom-based haptic line graphics for blind persons

Haptic interface technology has the potential of becoming an important component of access systems for people who are blind or visually disabled. The purpose of this study was to learn more about how a haptic interface, in this case the Phantom from SensAble Technologies, can be used to give blind persons access to 2D graphics and similar computer-based graphics. User tests were carried out with 24 blind users from Sweden and Italy. The tests included mathematical curves, haptic picture reliefs and haptic floor plans. This article reports on both technical solutions and results from the user tests. The results were influenced both by the nature of the different tasks and by individual differences among the test persons. 72% of the users managed to solve the applied mathematical problem that was the task for the mathematics program. The results for the picture reliefs were highly dependent on contextual information: 33%-66% of the users could identify the haptic picture reliefs without contextual cues, whereas more than 80% of the users could identify parts of the drawing once they knew what was depicted. More than 80% of the users could use the haptic floor plans. This research has implications for new ways in which blind persons can gain access to graphical information, even on the Internet.