Geometric feature-driven variable-topology toolpath planning for spatially evolving blade edges in robotic grinding

Aero-engine aerodynamic performance heavily depends on the profile accuracy of complex blade edges. Driven by complex aerodynamics, their variable cross-sectional evolution severely complicates consistent material removal across the entire domain. To address this issue, a variable-topology toolpath (VTT) method is proposed for generating cutter-contact (CC) point toolpaths on spatially evolving blade edges in robotic grinding. Specifically, the isonormal mapping algorithm constructs mapping equations under the constraint of normal angle measure conservation. Coupled with a physical boundary truncation mechanism, it generates adaptive toolpaths and establishes an error propagation model to strictly prove the global geometric approximation accuracy of the generated toolpaths. For step size optimization, the maximum chord error calculated by the DFP algorithm drives the dynamic adjustment of the search space via error ratios, strictly converging the error to the allowable tolerance to determine optimal CC points. To improve toolpath smoothness, a global smoothing algorithm based on B-spline quaternion initialization and Newton-Raphson iteration is developed to construct C 2 -continuous quintic PH splines that interpolate the discrete CC points, thereby ensuring second-order geometric continuity of the toolpath at the segment junctions. Finally, robotic grinding experiments on turbine blade leading edges (LE) are carried out to validate the proposed VTT method. The results demonstrate that the VTT method successfully ensures the profile accuracy of the entire LE, yielding a 65.79% improvement in surface profile accuracy compared to the traditional isoparametric (ISO-P) method.