Dynamic Drawing Guidance via Electromagnetic Haptic Feedback

TL;DR

This paper introduces a real-time electromagnetic haptic feedback system that guides drawing and handwriting tasks by gently correcting user pen movements, significantly improving accuracy without restricting user control.

Contribution

The paper presents a novel real-time electromagnet-based guidance system with a fast approximate model and a receding horizon control approach for error correction in drawing tasks.

Findings

Pen position control with 2.8mm dispersion

Significant accuracy improvement in user drawing tasks

Enhanced accuracy with increased shape complexity

Abstract

We propose a system to deliver dynamic guidance in drawing, sketching and handwriting tasks via an electromagnet moving underneath a high refresh rate pressure sensitive tablet. The system allows the user to move the pen at their own pace and style and does not take away control. The system continously and iteratively measures the pen motion and adjusts magnet position and power according to the user input in real-time via a receding horizon optimal control formulation. The optimization is based on a novel approximate electromagnet model that is fast enough for use in real-time methods, yet provides very good fit to experimental data. Using a closed-loop time-free approach allows for error-correcting behavior, gently pulling the user back to the desired trajectory rather than pushing or pulling the pen to a continuously advancing setpoint. Our experimental results show that the system can control the pen position with a very low dispersion of 2.8mm (+/-0.8mm). An initial user study indicates that it significantly increases accuracy of users drawing a variety of shapes and that this improvement increases with complexity of the shape.