Haptic Air Pen

Collaboration

This project was created during the course "Advanced Topics in Human-Computer Interaction" taught by  lecturer Juan Felipe Olaya Figueroa at BHT Berlin. We would like to thank him for his support throughout this course.

Project Description

The Haptic Air Pen is a handheld pen that lets you draw freely in the air. Your movements are translated into strokes on a canvas in real time and the pen feeds tactile sensations back into your hand as you go. A solenoid delivers crisp taps (pen touching down, the detents of the dial), while a vibration motor gives softer cues (drifting off the canvas, switching color, tool, or thickness). So you feel what you're doing while you draw, no need to glance at a menu.

How it works

The pen itself is deliberately simple: a 9-axis IMU tracks its orientation, and a rotary dial with a push button controls color, thickness, tool, and toggling drawing on and off. Those inputs stream over USB to a drawing app (built in Processing), which turns them into gestures and strokes and sends the haptic cues back to the pen.

Input: pen orientation (IMU) + a rotary dial with push button (color, thickness, tool, draw on/off).

Haptic output: a solenoid for crisp taps (pen-down, dial detents) and a vibration motor for graded cues (off-canvas, color/tool/thickness changes).

Controls

• Turn the dial → change color
• Turn + hold → change stroke thickness
• Short press → drawing on/off
• Long press → switch tool

References

[1] D. F. Keefe, R. C. Zeleznik, and D. H. Laidlaw, "Drawing on Air: Input Techniques for Controlled 3D Line Illustration," IEEE TVCG, vol. 13, no. 5, pp. 1067–1081, 2007. https://doi.org/10.1109/TVCG.2007.1060 

[2] H. Elsayed et al., "VRSketchPen: Unconstrained Haptic Assistance for Sketching in Virtual 3D Environments," in Proc. ACM VRST '20, 2020. https://doi.org/10.1145/3385956.3418953 

[3] B. L. Kodak and Y. Vardar, "FeelPen: A Haptic Stylus Displaying Multimodal Texture Feels on Touchscreens," IEEE/ASME Trans. Mechatron., vol. 28, no. 5, pp. 2930–2940, 2023. https://doi.org/10.1109/TMECH.2023.3264787 

[4] E. Kruijff, S. Biswas, C. Trepkowski, J. Maiero, G. Ghinea, and W. Stuerzlinger, "Multilayer Haptic Feedback for Pen-Based Tablet Interaction," in Proc. ACM CHI '19, 2019. https://doi.org/10.1145/3290605.3300373 

[5] X. Jian et al., "InkFlow: Connected Handwriting Recognition for Natural Mid-Air Input in Mixed Reality," in Proc. ACM CHI '26, 2026. https://doi.org/10.1145/3772318.3790596