RoboGraphics: Dynamic Tactile Graphics Powered by Mobile Robots
Darren Guinness, Annika Muehlbradt, Daniel Szafir, Shaun K. Kane · 2019 · Proceedings of the 21st International ACM SIGACCESS Conference on Computers and Accessibility (ASSETS 2019) · doi:10.1145/3308561.3353804
Summary
This paper introduces RoboGraphics, a novel approach to creating dynamic tactile graphics by combining a touchscreen tablet, static laser-cut tactile overlays, and small mobile robots (Ozobot Bit 2.0, approximately one cubic inch, ~$60 each). Traditional tactile graphics are limited to static content and cannot represent animation, motion, or interactivity. Existing solutions like shape displays can provide dynamic tactile output but are expensive and use custom hardware. RoboGraphics bridges this gap using off-the-shelf components: the touchscreen accepts user input and displays colour-coded control paths for the robots; the tactile overlay (laser-cut cardboard) provides the static background context such as graph axes, legends, and decorative elements; and the mobile robots serve as moving tactile markers that represent dynamic data points, characters, or interactive elements. The robots are controlled via optical sensors on their undersides that read colour codes displayed on the screen, enabling the software to direct them to specific positions. The system supports tactile "mounts" — small shaped attachments placed on top of robots to give them distinguishable identities (e.g., a turtle shape and rabbit shape for story characters). Five proof-of-concept applications were developed: a tactile bar chart with pageable datasets, an animated Tortoise and the Hare storybook, an analog clock with moving hands, a Braille letter teaching assistant, and an interactive cow digestive system exploration.
Key findings
In a user study with seven participants with varying levels of vision, the tactile bar chart application was compared against an audio-only touchscreen interface (no robots, with spoken directional guidance to find data points). Both conditions achieved identical accuracy (92.9%) on chart comprehension questions, and there was no significant difference in task completion time (tactile: 159.7s vs audio: 214.0s, p=.10). However, all seven participants preferred the tactile robot interface, rating it higher for both enjoyability (4.43 vs 3.14 on a 5-point scale) and informativeness (4.43 vs 3.57). Participants highlighted the gestalt understanding that robots provided — being able to touch all data points simultaneously and feel the overall shape of the data, something the audio interface could not offer. As P4 noted, "With the robots, you don’t have to find the data points because they are already there." The robot sounds during movement provided an additional information channel, with participants listening to travel time to infer relative values. The Tortoise and Hare application was the second most popular, with participants describing smiling throughout and wanting more stories. Participants suggested numerous future applications including pie charts, scatterplots, topographic maps, music notation, typography education, and narrative games. Key limitations included robots being too large for fine detail, occasionally being knocked off course by user touch, and content currently requiring programming to author.
Relevance
RoboGraphics presents a compelling middle ground between static tactile graphics (cheap but limited) and shape displays (dynamic but expensive). The use of commercially available robots and laser-cut cardboard makes this approach reproducible by educators and accessibility practitioners without specialised manufacturing capability. The finding that dynamic tactile graphics matched audio-only interfaces in accuracy while being strongly preferred has implications for how data visualisations are made accessible — the current standard of providing text descriptions or sonification alone may be insufficient when spatial understanding matters. The proof-of-concept applications demonstrate breadth: from STEM education (data charts, Braille learning) to creative storytelling, suggesting that dynamic tactile graphics could address the long-standing gap in accessible animated and interactive media. The tactile mount concept — giving identical robots distinguishable physical identities — is a practical design pattern applicable to any swarm robotics accessibility application. For practitioners, this work demonstrates that meaningful tactile interactivity does not require expensive custom hardware.
Tags: tactile graphics · robotics · blind · tangible interaction · data visualization · education · haptic technology · low-cost accessibility · dynamic display