Note
HaptiDraw
Drawing you can feel — a stylus and a haptic exoskeleton for blind users.
Note
A drawing tool for blind users: a stylus and a haptic exoskeleton that let you feel the line instead of seeing it.
Four-person team · MIT Reality Hack 2025 · Unity, Python, FastAPI, OpenCV, Haptikos exoskeleton, Logitech MX-Ink stylus
The problem
Every digital art tool assumes the person using it can see what they are making. Remove sight and almost nothing survives — not the canvas, not the cursor, not the feedback loop of drawing a line and looking at whether it went where you meant.
The interesting part is that the missing sense is not really vision. It is the glance: the free, continuous confirmation a sighted person gets that their hand is where they think it is. A blind user drawing has no way to check without stopping.
What it does
An image silhouette is traced into vector anchor points. The Haptikos exoskeleton drives feedback per finger, and the Logitech MX-Ink stylus vibrates when your hand drifts off the vertex you are following. So the line is not something you look at afterwards — it is something pushing back while you draw it.
The same mechanism works in reverse: because the drawing is a set of anchor points rather than a bitmap, an existing image can be handed to a user to read by touch.
The decision that made it work
Feedback on deviation, not on position. Reporting where the stylus is would mean constant vibration a user has to interpret continuously — noise pretending to be information. Reporting only when the hand leaves the intended line makes silence meaningful: no buzz means you are on the line, which is a signal a hand can follow without thinking about it.
Pairing that with per-finger haptics on the exoskeleton splits the two questions a hand is asking — am I on the line and what shape am I in — across two channels instead of overloading one.
What we learned
Touch did not substitute for sight so much as do a different job. Feedback through the hand let users build a mental map of the drawing — a sense of the whole shape and where they were inside it — which is the thing a sighted person gets from a glance and which no amount of describing the image aloud provides. Adding audio alongside the haptics helped, but the spatial understanding came from the hand.
Honest limits
This was built in a hackathon by four people against unfamiliar hardware, and it is a working demonstration rather than a validated tool. Getting the exoskeleton, the stylus and Unity to agree on a coordinate space took much of the available time, and calibrating the feedback so it read as intuitive rather than merely accurate was the hardest unsolved part.
What I’d change
Design the reading mode first. We built drawing and got reading as a consequence of the vector representation. Reading is probably the more useful half — being handed a diagram, a map, or someone else’s sketch and being able to feel it — and designing for that first would likely have produced a better drawing tool too.
Stop assuming the line is the goal. The system guides a hand along a predetermined silhouette, which is closer to tracing than to drawing. Tracing is the right first problem because it makes success measurable, but a tool for artistic expression eventually has to let someone make a mark nobody specified, and we did not get to what feedback means when there is no correct answer to deviate from.