One-Step Contour Error Pre-Compensation With Tracking Error Identification for Multi-Axis Machining

Multi-axis systems are widely used in various industries requiring synchronized contour motion with multiple degrees of freedom. Such systems include CNC machines and robots, where stringent demands for positional accuracy and dynamic response exist. This article proposed a novel contour error precompensation technique for multi-axis systems. The method models and compensates for tracking errors in the joint space directly, making it adaptable to any multi-axis system. Without involving kinematic transformations, the proposed approach is compatible with geometric error compensations. The method achieves high computational efficiency and ease of implementation by solving linear equations. When tracking errors are accurately predicted, the method minimizes contour errors in the actual trajectory while maintaining trajectory continuity. Additionally, a general method for identifying tracking error models in multi-axis servo systems is presented. Multiple trajectory experiments verify the robustness of the proposed identification method. Simulation results demonstrate that compared to the mirror method, the proposed approach offers advantages in computational efficiency, residual contour error, and kinematic continuity. Furthermore, flank milling experiments show that after compensation using the proposed method, the allowable distribution range on the milled surface increased by 19.7% within a 20 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i>m tolerance.