TSP-Bot: Robotic TSP Pen Art using High-DoF Manipulators

TSP art is an art form for drawing an image using piecewise-continuous line segments with no crossings. This paper presents a robotic pen drawing system capable of creating complicated TSP pen art on a planar surface using multiple colors. The system begins by converting a colored raster image into a set of points that represent the image's tone, which can be controlled by adjusting the point density. Next, the system finds a piecewise-continuous linear path that visits each point exactly once, which is equivalent to solving a Traveling Salesman Problem (TSP). The path is simplified with fewer points using bounded approximation and smoothed and optimized using B\'ezier spline curves with bounded curvature. Our robotic drawing system consisting of single or dual manipulators with fingered grippers and a mobile platform performs the drawing task by following the resulting complex and sophisticated path composed of thousands of TSP sites. As a result, our system can draw a complicated and visually-pleasing TSP pen art with high accuracy and efficiency. We also demonstrate that our system can draw TSP pen art on a large wall, which is very hard for a human artist to achieve.