Uniform Coverage Tool Path Generation for Robotic Surface Finishing of Curved Surfaces

Abstract

We provide a novel solution to the problem of robot tool path generation to uniformly cover the surface area of a curved surface with varying curvatures by using a circular, flat finishing tool. We first develop a local contact shape descriptor using tools from differential geometry to estimate the contact shape and its area between the finishing tool and the workpiece surface under an applied normal force. Based on this varying contact area as the tool moves on the surface, we describe a tool path planning strategy that provides full and uniform coverage of a free-form or curved surface with the least amount of overlap. As opposed to fixed spacing paths with point contact in most existing approaches, we provide a novel path generation method where the interval spacing between neighboring path segments is determined by the contact area, which is position-dependent and varies along the surface in accordance with its principal curvatures. An efficient bisection method is employed in the proposed off-line path planning strategy. Numerical studies were conducted for ruled and general curved surfaces to compare the contact areas and coverage of the resulting path with paths generated using two other approaches from the literature. Real-time surface finishing experiments with a six degree-of-freedom robot equipped with a surface finishing tool were also conducted for both these surfaces to validate the proposed approach. Results from the numerical studies and experiments are presented and discussed.