Calligraphy Brush Trajectory Control of by a Robotic Arm

Hsien-I Lin,Xuechao Chen,Tian-Tsai Lin

doi:10.3390/app10238694

Abstract

This study proposed a calligraphy brush trajectory model for the behavior of brush movements and provided the three-dimensional handle coordinates for a robotic arm to write calligraphy. This study dealt with basic footprints and bent lines of calligraphy and proceeded as follows. The shape of brush footprints on paper was measured, which provided the positions of the brush relative to its handle. These brush footprints were scanned and corrected for skew using the Direct Linear Transformation. The outer frame of each basic footprint was characterized using Bézier curves. Bent lines were drawn to derive the brush trajectory model, and it was used to derive the relationship between the trajectories of the brush and handle. By characterizing the changes in the footprints with handle displacement, we obtained the relationship between the handle coordinates and the position and shape of the brush footprints. The written characters were evaluated based on their size, position, and stroke balance, with a maximum score of 100 in each category. The average score of the “Yong” character written using our brush trajectory model was approximately 94 points; when the handle coordinates were fixed to the center of each footprint, the average score was only 88 points.

Highlights

Chinese calligraphy is generally taught and learned by the lintie or motie approaches
We converted the coordinates of this trajectory into handle coordinates according to the footprints’ sizes, which are transferred to the robotic arm
As the writing process is clearly illustrated by the handle coordinates, this approach can be used as an aid in the teaching of calligraphy

Summary

Introduction

Chinese calligraphy is generally taught and learned by the lintie or motie approaches. The copybook is placed under a sheet of paper, and the learner learns how to write by “filling” the shape of the word on said sheet of paper. We converted the coordinates of this trajectory into handle coordinates according to the footprints’ sizes, which are transferred to the robotic arm. The aim of this study is to imitate copybook models and allow the users of this system to write arbitrary Chinese characters using a robotic arm. This system can be used to aid teaching of calligraphy

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Discussion

Conclusion