PaintCopter: An Autonomous UAV for Spray Painting on Three-Dimensional Surfaces

This letter describes a system for autonomous spray painting using an unmanned aerial vehicle (UAV), suitable for industrial applications. The work is motivated by the potential for such a system to achieve accurate and fast painting results. The PaintCopter is a quadrotor that has been custom fitted with an arm plus a spray gun on a pan-tilt mechanism. To enable long deployment times for industrial painting tasks, power and paint are delivered by lines from an external unit. The ability to paint planar surfaces, such as walls in single color, is a basic requirement for a spray painting system. But this work addresses more sophisticated operation that subsumes the basic task, including painting on three-dimensional (3D) structure, and painting of a desired texture appearance. System operation consists of (a) an offline component to capture a 3D model of the target surface, (b) an offline component to design the painted surface appearance and generate the associated robotic painting commands, and (c) a live system that carries out the spray painting. Experimental results demonstrate autonomous spray painting by the UAV, doing area fill and versatile line painting on a 3D surface.

I. Introduction

Robotic painting using a UAV has the potential to produce accurate (predictable and repeatable) painted appearance, to be low-cost, and to avoid the need for scaffolding and ladders. This motivates our work on PaintCopter for autonomous spray painting. A basic painting task is to paint a planar surface such as a wall in a single color. This letter attacks a larger challenge that subsumes the more basic task in two ways - with the ability to paint on 3D structure, and to paint texture. Fig. 1 provides an illustration in which painting is being done on a synthetic rock, and the goal is to paint a uniform base color and then to overlay color striations, in order to produce a (user-designed) rock-like surface appearance. This type of task - with the two dimensions of painting on a 3D object and painting a texture for theming/styling - is the motivation for our work. It requires a more sophisticated approach than the single color wall painting problem, and explains design choices that might have been avoided with more basic functionality - for example, the use of a spray gun on a pan-tilt unit (PTU) instead of on a rigid mount.