Ultraprecision Contouring Control with Enhanced Accuracy and Robustness: An Online Prediction Based Real-Time Iterative Compensation Method

This article proposes an online prediction based real-time iterative compensation (RIC) method with enhanced accuracy and robustness for ultraprecision contouring control tasks. Unlike conventional feedback-centric online contouring error compensation methods, the proposed contouring RIC method can preemptively identify and suppress potential contouring errors before their occurrence. Initially, a precise online contouring error prediction model is established to predict upcoming contouring errors in advance. Subsequently, a real-time iterative compensation mechanism is proposed to online generate optimal trajectory compensation signals for contouring error reduction. Various contouring tasks are executed on an ultraprecision air-bearing motion stage. The proposed contouring RIC method consistently reaches sub-7-nm-level extreme contouring accuracy over a 100-mm motion stroke even under trajectory alternations and complicated external disturbances. Notably, it matches the accuracy limit of high-precision iterative learning control (ILC) while remarkably surpassing ILC on robustness. The proposed method is promising to enhance the ultraprecision multi-axis manufacturing performance of practical mechatronic systems through advancements in motion control technology.