Five-Axis Trochoidal Sweep Scanning Path Planning for Free-Form Surface Inspection

Abstract

Freeform surface inspection is a vital process in manufacturing, and the newly emerged five-axis continuous sweep scanning technology is one of the most efficient and accurate means for free-form surface inspection. The key in employing the five-axis inspection technology is to plan an effective and efficient sweep scanning path respecting both the inspection surface and the properties of the inspection device. Current sweep scanning paths suffer from the oscillating pattern that forces the high-speed stylus of the five-axis inspection device to swing back and forth frequently, which imposes excessive kinematic loading on the probe head, and in turn, undermines the inspection stability and efficiency. In this paper, we present a new trochoidal sweep scanning path for freeform surface inspection. The proposed method is novel in that the generated inspection path is a smooth trochoidal-shaped curve on the surface without causing any oscillation during a sweep scanning process. The kinematic performance of the probe head is significantly improved, which enables much better inspection stability and efficiency. Both computer simulation and physical inspection experiments of the proposed method have been conducted, whose results convincingly validate the feasibility and superiority of the proposed trochoidal sweep scanning path over the traditional oscillating sweep scanning path in terms of inspection stability and efficiency. Note to Practitioners—This work is motivated by the high requirements on the stability and efficiency of the newly emerged five-axis sweep scanning technology for freeform surface inspection. A novel trochoidal sweep scanning path is generated to make the original heavy-loaded rotary axes of the five-axis inspection machine move smoothly without needing frequent acceleration and deceleration as suffered from a traditional five-axis oscillating sweep scanning path. The kinematic loads of the five-axis inspection device are significantly reduced based on the proposed sweep scanning path; thus, the inspection machine could afford a higher sweep velocity of inspection, and the inspection stability and efficiency could be improved considerably as well. Compared with a traditional oscillating sweep scanning path, in our tests, the proposed method can improve the inspection efficiency by more than 20%, while the maximal kinematic loads (e.g., the velocity and jerk of the C-axis) can be reduced by 55%-85%. With superior inspection efficiency and stability, the proposed trochoidal sweep scanning path can be utilized for accurate and efficient inspection of large freeform surfaces like those in the aerospace and automotive industries.